Automatically Switched Equalization Circuit

Transcript

SERIAL NUMBER ............... FILING DATE I I CLASS ....... SUBCLASS . . ... ... ' . EXAMINER ' ................ ................ U.S. DEPT. of COMMERCE Patent and Trademark Offlce-PCT436L (rei ALdF 'ARTS OF APPLICATION ILED SEPARATELY Applications Examiner JOTICE OF ALLOWANCE MAILED CLAIM-S ALLOWED , I tpy"I Sheets Drwg, 'Figs. . PhntT' \ I r Label Area Form P T 0 4 6 A (Rev. 8/92) 1 DRAWING ISSUE FEE " I I Print Cal m i, Total Claims,/ Assistant Examiner $' 476 Phkhary Examiner PREPARED FOR ISSUE i --. -:?q/ /FACF\ J / IAR CODE LABEL U.S . PATENT APPLICATION FILING DATE SERIAL NUMBER 08/509,160 CLASS 07/31/95 381 GROUP ART UNIT 2608 I- DANIEL A. PALMER, SEMI VALLEY, CA. **FOREIGN/PCT APPLICATIONS************ VERIFIED TATE OR ,OUNTRY CA u SHEETS DRAWING 1 TOTAL CLAIMS INDEPENDENT CLAIMS 16 5 FILING FEE RECEIVED $882.00 ATTORNEY DOCKET NO. 774710046014 AUTOMATICALLY SWITCHED EQUALIZATION CIRCUIT - 4 This is to certif that annexed hereto is a true co y from the records of the United States Patent and TraJetnark Office of the application vvtich is identified above. By authority of the COMMISSIONER OF PATENTS AND TRADEMARKS Date Certifying Officer Date Received Mired 11111111111111 1 1111111111US00558 1111111111111111626A 111111111111111111 11111111111 United States Patent [I]] [I91 Palmer (451 Patent Number: Date of Patent: 5,581,626 Dec. 3, 1996 5,056,148 loll991 Hayashi .................................... 5,161,198 11/1992 Noble ...................................... [54] AUTOMATICALLY SWITCHED EQUALIZATION CIRCUIT 381125 381/123 [75] Inventor:, Daniel A. Palmer, Semi Valley, Calif. Primary Examiner-Forester W.Isen Attorney, Agent, or Firm-Jones, Day, Reavis & Pogue [73] Assignee: Harman International Industries, Inc., Northridge, Calif. I571 [21] Appl. No.: 509,160 [22] Filed: Jul. 31, 1995 [51] Int. (21.6 ....................................................... H03G 5/00 [52] U S . C1. ............................................. 3811103; 3811123 [58] Field of Search ...................................... 381/102, 103, 381/123, 120, 25, 74, 98, 27 1561 References Cited U.S. PATENT DOCUMENTS 4,433,209 4,763,012 4,949.384 5,050,214 U1984 8/1988 8/1990 9/1991 Kurosawa et al. ........................ Blankenship ............................ Noro et al. .............................. Lee ............................................ 381/25 3811123 3811123 381/74 ABSTRACT A circuit in which, when loudspeakers are being used by themselves, the equalization to the loudspeakers is optimized for full range operation and only the intended filters for full range operation are inserted into the circuit path. When a subwoofer is added to the system to handle low frequencies, the subwoofer mating connector is inserted into a connector jack to receive the audio signals and simultaneously inserts high pass filters into the circuit for the speakers so they operate in the mid range and high frequency range where they are better suited. The subwoofer handles and reproduces the low frequencies. The result is louder and clearer satellite speakers that exhibit a much lower tendency to clip the signals from the amplifier driving them. 16 Claims, 1 Drawing Sheet U.S. Patent 5,581,626 Dec. 3, 1996 + I I I 22 R 1~i : FIG. I vso 543 66 I ’ <- l - I FIG. 2 68 FILTER OUTPUT LOUDSPEAKER INPUT ++B,:[iqy LOUDSPEAKER INPUT FILTER OUTPUT v + 0 L r 82 -A-$;qz; FILTER OUTPUT FIG. 4 -- LOUDSPEAKER INPUT 5,581,626 2 1 AUTOMATICALLY SWITCHED EQUALIZATION CIRCUIT BACKGROUND OF THE INVENTION 5 1. Field of the Invention The prcscnt invention relates to equalization circuits in gencral and in particular to a circuit that enables the equalization of loudspeakers to be automatically switched when an optional subwoofer is added to an entry level two-speaker 10 audio system. 2. Dcscnption of Related Art When a pair Of loudspeakers are designed for listening to music or any other program material, the equalization to those spcakcrs is normally optimized lor full range fre- * 5 qucncy operation, commonly 20 Hz-20 kHz. Activc and/or passive filtcrs arc rcquired to obtain flat frequency response for full range operation and these types of filters are commonly used in loudspeaker systems to correct for nonfrequency response. Transducers which are small 20 and inefficientare not optimum for low frequency operation; considerations and/or lack of available howcvcr, due to space inside smaller loudspeaker enclosures (such as multimedia speakers), these small transducers are commonly uscd despite thcir relatively poor ability to reproduce low 25 kequcncies and despite limited power handling capacity. A 2.5 to 3 inch diameter transducer, for example, may only be cfkctivc down to 200 to 300 Hz,whereas typical program material cxtends down to approximately 20 Hz. These smaller transducers are better suited as satellite speakers for 30 handling mid to high frequency program material. When a subwoofer is added to a loudspeaker system, the lowfrequency information in the program material will be handled by the subwoofer; however, if the smaller, less cficient transducers are still subjected to those Same low 35 frequencies and high excursion, they needlessly labor to reproduce low frequencies, consuming excess power, causing thc speaker to distort and causing the sound quality to be less than optimum. The system is not Smart enough to how that the subwoofer has been connected. Thus, in the prior art, 40 if a subwoofer is desired to be added to the system, a manually operated switch or switches must be used to change filters that are connected to the left and right speakers and to route any signals to the subwoofer. 45 SUMMARY OF THE INVENTION In the present invention, when an electrical connector is inserted into the subwoofer output jack, the insertion is sensed and automatically causes the necessary switches to so be operated. The activation of the switching means causes the low frequency drive to the smaller satellite speakers to be substantially reduced. This allows the satellite speakers (which are normally quite small and tend to be weak at low frequencies) to operate in the mid range and high frequency 5s range for which they are best suited. In doing this. the power dissipation in thc smaller satellite speakers is reduced dramatically due to the fact that they are no longer required to reproduce the low frequencies that are being fed to the subwoofer. In many cases this is critical since a low-cost, 60 low-current wall transformer is typically used to power the satellite amplifiers and therefore provides a limited supply voltage and current. Due to the loading of the power supply when the amplifier reproduces low frequencies, the available output power for mid and high frequencies is substantially 65 diminished thus causing distortion at all frequencies and inefficient use of the power supply. The result of the present invention is louder and clearer sounding satellite speakers exhibiting a much lower tendency to clip thc amplifier signals driving them due to a significant decrease in low frequencies. In the present invention, a stereo minijack with a DPDT switch is used at the subwoofer output jack or connector. When the subwoofer output jack or connector is unused (no plug inserted), the audio signal is caused by the DPDT switch in the jack to be routed such that full range frequencies are fed to the amplifier output sections and thence to the satellite loudspeakers. When the subwoofer output jack is used (plug inserted), the audio signal is caused by the DPDT switch in the jack to be routed such that only mid range and high frequencies are fed to the amplifier output sections and satellite speakers. The amplifiers and power supply for the satellite speakers are no longer subject to the low frequencies which will now be reproduced by the subwoofer through the plug inserted in the output jack. Thus, in one condition, when the satellite speakers are being used by themselves, the equalization to the satellite speakers is optimized for full range operation and only the intended filters for full range Operation are inserted into the circuit path. In the second state, when a subwoofer is added to the system and has a connector inserted into the subwoofer output jack, a switch integrated into the subwoofer output jack causes the signals to be rerouted to appropriate filters that move the comer frequency of the high pass filters (-3 dB point) out to a higher frequency. As stated previously, this allows the satellite speakers (which are normally quite small and tend to be weak at low frequencies) to operate in the mid range and high range where they are better suited. Thus, the power dissipation in the smaller satellite speakers is dramatically reduced due to the fact that they are no longer required to reproduce the low frequencies which are fed to the subwoofer that has been added to the system. As stated, the result is a louder a d clearer sound from the satellite speakers because h e y exhibit a m ~ c h lower tendency to clip the signals from the amplifier driving them. Thus it is an object of the present invention to provide an automatically switched equalization circuit that allows full range frequency audio frequency signals to be coupled to a loudspeaker and which automatically couples only mid and high frequency range audio signals to the loudspeaker when a woofer or low frequency audio loudspeaker is connected to the system. It is another object of the present invention to use an automatically switched equalization circuit with left and right audio channel loudspeakers. It is still another object of the present invention to modify an audio loudspeaker system utilizing a pair ofmid and high frequency range speakers by adding a low frequency range speaker that automatically disconnects low frequency range signals from said pair of mid range to high frequency range speakers. Thus the present invention relates to an automatically switched equalization circuit for an audio loudspeaker of the mid and high frequency ranges including audio input signals, a jack for receiving a connector that couples the audio signals to a low frequency range loudspeaker, a switch associated with the jack having first and second positions, the first position of the switch coupling a full frequency range audio signal to the audio loudspeaker, the second position of the switch coupling a mid frequency range and high frequency range audio signal to the audio loudspeaker 5,581,626 3 4 and the switch being in the first position when the low frequency range loudspeaker is unused and being in the second position when the low frequency range loudspeaker is used and the connector is inserted in the jack. intended to mean the range of 200-20 kHz generally and in the preferred range of 300 Hz to 20 kHz. If it is decided to add a subwoofer to the loudspeaker system, such subwoofer would handle frequencies from 20 Hz-300 Hz, the low frequency information in the program material. However, if the smaller, less efficient transducers 28 and 30 are still subjected to these same low frequencies and high excursion, they needlessly labor to reproduce low frequencies, consume excess power, distort the audio signals, and cause the sound quality to be less than optimum. The system is not smart enough to know that the subwoofer has been added to the system. In the present invention, if a subwoofer is desired to be added, a jack 48, which may be a stereo minijack, is coupled to the output of an amplifier 46 whose inputs are coupled to the audio sources 12 and 14. When a connector for the subwoofer is inserted into the output jack 48, it makes contact with terminals 50 and 52 to receive the audio frequency signals. It will be sensitive primarily to the low frequency signals 20 Hz-300 Hz because of its construction. However the insertion of the connector into the jack 48 is sensed by a second arm 54 that is mechanically coupled to switches 42 and 44. Switches 42 and 44 are caused to move from their connection to output terminals 58 and 60 of the full range filters 32 and 36 to the output terminals 62 and 64 of the respective high pass filters 34 and 38. This allows the satellite speakers 28 and 30 (which, as stated previously, are normally quite small and tend to be weak at low frequencies) to operate in the mid range and high frequency range (300 Hz-20 kHz) for which they are better suited. In doing this the power dissipation in the smaller satellites 28 and 30 is reduced dramatically due to the fact that they no longer are required to attempt to reproduce the low frequencies now being fed to the subwoofer coupled to jack 48. In many cases, this is critical since a low-cost, low-current wall transformer is typically used to power the satellite amplifiers and headroom in the enclosure is at a premium. The result of this automatic switching scheme therefore is louder and clearer sounding satellite speakers 28 and 30 that exhibit a much lower tendency to clip the amplifier signals from amplifiers 24 and 26 that drive them because there is a significant decrease in low frequencies coupled to the loudspeakers 28 and 30. Thus, when the subwoofer output jack 48 is unused, that is, no plug is inserted therein, the audio signal is routed through the switches 42 and 44 such that full range frequencies from filters 32 and 36 are fed to the amplifier output sections 24 and 26 and thence to the satellite loudspeakers 28 and 30. When the subwoofer output jack 48 is used and a plug or connector is inserted therein, switches 42 and 44 are then activated to cause the audio signal to be routed through the switches 42 and 44 such that only mid range and high frequencies (300 Hz-20 kHz) from high pass filters 34 and 38, respectively, are fed through the amplifier output sections 24 and 26 and thence to the satellite speakers 28 and 30. The amplifiers 24 and 26 and the power supply for the satellite speakers are no longer subject to the low frequencies that will now be reproduced by the subwoofer. Therefore it can be seen that in the first state, when the satellite speakers 28 and 30 are used by themselves, the equalization to the speakers 28 and 30 is optimized for full range operation and only the intended filters 32 and 36 are inserted into the circuit path by switches 42 and 44. However, when a subwoofer is to be added to the circuit, and a connector is inserted into the jack 48, through the use 5 BRIEF DESCRIPTION OF THE DRAWINGS These and other features of the present invention will be more fully disclosed when taken in conjunction with the following DETAILED DESCRIPTION OF THE DRAW- io INGS in which like numerals represent like elements and in which: FIG. 1 is a schcmatic diagram of thc novel automatically switched equalization circuit; FIG. 2 is a schematic arrangement of a Hall effect switch 15 that can be used as the switch that provides the automatic switching of the equalization circuit; FIG. 3 is a general diagram illustrating the use of an electronic devicc as the switch for providing the automatic 20 equalization; and FIG. 4 is a schematic arrangement of an optical device that can be used as the switch to provide the automatic equalization. 25 DETAILED DESCRIPTION OF THE PRESENT INVENTION A two speaker audio system 10 is shown in FIG. 1 and has audio inputs 12 and 14 feeding two channels 16 and 18 30 which may be left and right channels for the two-speaker system. The invention, howcver, would work with a single speaker as will be seen hereafter. Each of the left and right channels 16 and 18 has an input amplifier 20 and 22, respectively. They also have respective output amplifiers ZQ 35 and 26 which drive the respective speakers 28 and 30. The audio signals, after being amplified by amplifiers 20 and 22 in each of the channels 16 and 18, are coupled to full range filters 32 and 36, respectively. A switching unit 40 has a switch 42 in the left channel that is coupled to output 40 tcrminal 58 of the full range filter 32 and couples the full range audio signals to amplifier 24 and thence to speaker 28. In like manner, in the right channel 18, the output of amplifier 22 is coupled to full range filter 36 whose output on terminal 60 is coupled through switch 44 to amplifier 26 45 that drives speaker 30. It is to be understood that when a pair of loudspeakers such as 28 and 30 in FIG. 1 are designed for listening to music or any other program material, the equalization to those speakers is normally optimized for the full frequency range operation which is commonly 20 Hz-20 50 kHz. The full range filters 32 and 34 are required to obtain flat frequency response in the full range operation and these types of filters are commonly used in loudspeaker systems to correct for non-uniform frequency response. Transducers that are small and inefficient, and typically forming the 55 loudspeakers 28 and 30, are not optimum for low frequency operation. However, due to cost considerations and/or lack of available space inside smaller loudspeaker enclosures, these small transducers are commonly used despite their relatively poor ability to reproduce low frequencies and 6o despite limited power handling capacity. Such a speaker may be a 2.5-3 inch diameter transducer and may be effective only down to 200-300 Hz whereas typical program material extends down to approximately 20 Hz. Thus these smaller transducers 28 and 30 are better suited as satellite speakers 65 for handling mid to high frequency program material. As defined herein, mid to high frequency program material is 5,581,626 5 of a switch intcgrated into the jack 48, the signal is rerouted to high pass filters 34 and 38 by switches 42 and 44 where the comer frcquency (-3 dB point) of the high pass filter is moved to a higher frequency. This allows the satellite speakers to operate as stated earlier in the mid range and 5 high frequency range where they are better suited. The low frequencies are fed to the subwoofer coupled to jack 48. Clearly the switches 40 shown in FIG. 1 are intended to be diagrammatic in representation and may t&c the form of a numbcr of different typcs of switches. They may be io mechanical switchcs as shown, all operated by the insertion of a conncctor in jack 48 in a well-known manner. However, the switches could be magnetically operated a illustrated in FIG. 2. In FIG. 2, connector 54 is part of jack 48 shown in FIG. 1 and whcn a connector is inserted in the 15 a magnet 66 in close associajack 48, connector 54 tion with a Hall device 68 which is in effect a switch that couples the filtcr output from the high pass filter 34, for cxamplc, as the input to the loudspeaker amplifiers 24 or 26. In like manner, such a all effect switch could be operated 20 in a revcrsc process. That is, it could disconnect the switch 42 from the full range filter 32 and switch 44 from full range filtcr 36. In FIG. 3, an electrical device is shown as the switch, or a uortion of switch devicc 40. In FIG.3. inout arm 54 can 25 bc' the samc arm 54 shown in FIG. 1 in j a c i 48 and could supply a voltage through contact arm 72 to an electronic device such as a MOS transistor 74. Proper voltage is supplied to the MOS 74 at terminal 76. When the switch terminals 54 and 72 are closed, the MOS may be made either 30 to conduct or nonconduct as desired. If it is to conduct, it could couple the high pass filter 34 output on terminal 78 to the loudspeaker input on line 80 which would be coupled to the amplifiers 24 and 26, respectively, in their respective 35 channels. One of such switches would be used to open the connection to the full range amplifier 32 and close the connection to the high pass filter 34. FIG.4 illuslrates a general optical circuit that could be . used as the switches 40 in FIG. 1. Again, the arm 54 could 40 be the arm 54 illustrated in FIG. 1 which, when the woofer is added and the connector is inserted in jack 48, am^ 54 is brought into contact with arm 82, thus supplying a voltage to a light emitting device 84 which generates a light represented by arrow 86. This light activates a photoelectric 45 device 88 causing it to conduct and connect the input 90 to the output 92. The input 90 could be the output of the high pass filters 34 or 38 and the output 92 could be the input to the amplifiers 24 or 26 that drive the loudspeakers 28 and 30. Clcarly the devices could be made to operate in the reverse 50 direction to disconnect a full range filter from the output amplifiers 24 and 26. One skilled in the art will understand how to use each of the circuits shown in FIGS. 2 , 3 and 4 to provide the proper switching arrangement 40. Thus therc has been disclosed a novel automatically 55 switched equalization circuit where, when satellite speakers are bcing used by themselves and these speakers are small and inefficient and not optimum for low frequency operation and arc suitable down to an effective frequency range of 200-300 Hz, the equalization of the satellite speakers is 60 optimized for full range operation and only the intended filters for full range operation are inserted into the circuit path. However, when the connector is inserted into an output jack to connect a subwoofer to the system, a switch, inte- 65 grated into the jack or associated with the jack, reroutes the audio signals to filters that move the comer frequency of the 6 high pass filter (-3 dB) out to a higher frequency. This allows the satellite speakers (that are normally quite small and tend to be weak and low frequency) to operate in the mid-range and high frequency range (300 Hz-20 Mz) where they are better suited. In doing this, the power dissipation in the smaller speakers is reduced dramatically due to the fact that they no longer are required to reproduce the low Speakers now being fed to the subwoofer. The result iS louder and clearer satellite speakers exhibiting a much lower tendency to Clip the signals from the amplifier driving them. This becomes critical for a bw-Current Wall transformer used to power the satellite amplifiers which produces a limited and Due to lhe loading of the power when the amp1ifier reproduces low quencies, the available output power for mid and high frequencies is substantially diminished thus causing distortion at all frequencies and inefficient use of the power While the invention has been described in connection with a preferred embodiment, it is not intended to limit the scope of the invention to the Particular form set forth, but, on the co~trary,it is intended to cover such alternatives, modifications, and equivalents as may be included within the 'pint and scope Of the invention a defined by the appended I claim: 1. An automatically switched equalization circuit for a set of left and right channel audio loudspeakers of the mid and high frequency ranges including: left and right channel audio input signals; a stereo jack for receiving a connector that couples the left and right audio signals to a low frequency loudspeaker; a switch associated with said stereo jack having first and second positions; said first position of said switch coupling a full frcquency range audio signal to the left and right channel loudspeakers; said second position of said switch coupling only mid frequency and high frequency audio signals to said left and right channel loudspeakers; and said switch being in said first position when said low frequency range loudspeaker is unused and being automatically placed in said second position when said low frequency range loudspeaker is used and said connector is inserted into said stereo jack. 2. An automatically switched equalization circuit as in claim 1 further including: full frequency range filters for coupling said audio signal to said left and right speakers when said switch in said first position; and high pass filters for coupling said audio signals to said left and right loudspeakers when said switch in said second position. 3. An automatically switched equalization circuit as in claim 2 further including: a first audio amplifier in each of said left and right audio channels for amplifying said audio signals prior to being filtered by both said full frequency range filters and said high pass filters; and a second audio amplifier in each of said left and right audio signal channels prior to the corresponding left or right channel loudspeakers for amplifying either the full range audio signals or the high pass frequency audio signals as selected by said first and second switch positions. 5 5 8 1,626 7 8 10. A loudspeaker system including: claim 1 wherein said switch associated with said stereo jack left and right channel audio signal input terminals; is a Hall effect switch. left and right loudspeakers generally suited for handling 5. An automatically switched equalization circuit as in mid to high range audio frequencies; claim 1wherein said switch associated with said stereo jack 5 left and right full range filters, each having an input is an electronic switch. coupled to one of said left and right channel signal 6. An automatically switchcd equalization circuit as in input terminals and an output normally coupled to its claim 1 wherein said switch associated with said stereo jack corresponding left or right loudspeaker; is an optical switch. left and right high pass frequency filters, each having an 7.An automatically switchcd equalization circuit as in 10 output for coupling to a corresponding one of said left claim 1 wherein said stereo jack is an miniature jack. and right loudspeakers and having an input coupled to 8. In a loudspeaker system having at least one loudspeaker one of said left and right channel signal input terminals; coupled to an input audio signal through a full range audio a connector jack for a low frequency range loudspeaker frequency filter, the improvement including: being couplcd to said left and right channel audio input a high pass filter having an input for receiving said audio 15 signal terminals, said connector jack for receiving a input signal and having an output; low frequency range loudspeaker mating connector; an input connector for a low frcquency loudspeaker, said and input connector receiving said input audio signals; switch means coupled to said connector jack for autoa switch having an output coupled to said at least one matically disconnecting said left and right loudspeakers loudspeaker and having an input for selective coupling 20 from said left and right full range filters and coupling a corresponding one of said left and right high pass between said full audio frequency range filter and said frequency filter outputs to corresponding ones of said high pass filter output; and left and right loudspeakers when a low frequency range switch control means coupled to said switch and operated loudspeaker mating connector is coupled to said conby said low frequency speakcr input connector such nector jack so as to enable said left and right loudthat when a low frequency speaker is connected to said 25 speakers to operate more efficiently. input connector, said switch couples only said high pass 11. A loudspeaker system as in claim 10 wherein said filter signals to said at least one loudspeaker. switch means i'urther includes: 9. A circuit for coupling left and fight channel audio a single-pole double-throw switch in each of said left and signals to a set of corresponding left and right loudspeakers, 30 right audio channels; said circuit including: said single-pole of each switch being connected to a a first input amplifier for each of said left and right corresponding one of said left and right loudspeakers; channels for amplifying said audio signals; one terminal of said double-poles of each switch being an equalization circuit coupled to the output of each said connected to a corresponding one of said outputs of first amplifiers in each of said left and right channels; 35 said full range filters; said equalization circuit providing both full range audio the other terminal of said double-poles of each switch frcquency output signals and high pass audio frequency being connected to a corresponding one of said outputs signals for each of said left and right channels; of said high pass frequency filters; and said left and right loudspeakers operating in the mid said single-pole of each said switch being moved from 40 frequency to high frequency range; said one of said double-pole terminals to said other one of said double-pole terminals when said low frequency a second amplifier having an input coupled to and receivrange loudspeaker mating connector is coupled to said ing both of said left and right channel audio signals and connector jack to automatically cause only audio fregenerating audio output signals; quencies in the high pass range to be coupled to said first and second single-pole double-throw switches, each 45 left and right loudspeakers and only low audio frequenswitch having an output terminal coupled to a correcies to be coupled to said low frequency loudspeaker. sponding left or right loudspeaker and a first input 12. A loudspeaker system as in claim 11further including terminal for receiving a corresponding left or right full an audio amplifier coupled between each audio input termirange audio frequency output signal from said equalizer and a second input terminal for receiving a correspond- 50 nal and each full range filter and high pass filter. 13. A loudspeaker system as in claim 10 wherein said ing left or right high pass audio frequency signal from switch means includes: said equalizer; a Hall effect switch having an input coupled to the output a supplemental low frequency loudspeaker connector jack of one of said filters and an output coupled to a coupled to the output of said second amplifier for corresponding one of said left and right loudspeakers; receiving a low frequency loudspeaker connector; and 55 and switch control means coupled to said single-pole doublea magnet associated with said Hall effect switch and throw switches and to said low frequency loudspeaker operated only when said low range loudspeaker mating connector jack such that when a low frequency loudconnector is inserted in said connector jack to energize speaker connector is inserted in said supplemental said Hall effect switch and effect the connection loudspeaker connector jack, said single-pole doubIe- 60 between each said high pass filter and a corresponding throw switches are operated to couple only high pass left or right loudspeaker. filter signals to said first and second loudspeakers and 14. Aloudspeaker system as claim 10 wherein said switch when said low frequency loudspeaker connector jack is includes: not inserted in said supplemental loudspeaker connector jack, said single-pole, double-throw switches 65 an MOS device having an input coupled to the output of couple only full range audio frequency signals to said one said filters and output coupled to a corresponding one of said left and right loudspeakers; left and right loudspeakers. 4. An automatically switched equalization circuit as in 5,581,626 9 a control bias connection couplcd to said MOS device to opcratc said MOS device; and a bias voltage coupled through said connector to said control bias connection such that said MOS device is operated to effect the said coupling between said high 5 pass filtcr and its corresponding left or right loudspeaker only when said low frequency range Ioudspeaker mating connector is inserted in said connector jack. 15. A loudspeaker system as in claim 10 wherein said 10 switch means includes: an optical device for each filter, each device having an input coupled to the output of one of said filters and an output coupled to a corresponding one of said left and 15 right loudspcakers; a light sourcc associated with each optical device for activahg said optical device to effect thc connection between said filter output at its corresponding left or right speaker; and 20 a powcr source coupled through said connector to control said light source only when low frequcncy range loudspeaker mating connector is inserted in said connector jack. 16. An automatically switched equalization circuit for a 25 single audio loudspeaker of the mid and high frequency rangcs including: 10 audio input signals; a connector jack for receiving a mating connector that couples the audio signals to a low frequency range loudspeaker; a switch associated with said connector jack and having first and second input terminals and an output terminal coupled to said single audio loudspeaker. said switch being operated between said input terminals when said mating connector is inserted in said connector jack; said first input terminal of said switch receiving a full frequency range of audio signals for the single audio loudspeaker; said second input terminal of said switch receiving only a mid frequency range and high frequency range of audio signals for said single audio loudspeaker; and said switch being coupled to said first terminal when said low frequency range loudspeaker is unused and being coupled to said second terminal when said low frequency range loudspeaker is used and said mating connector is inserted in said connector jack. * * * * * I I ATLANTA LON.'ON BRUSSELS LOS ANGELES CHICAGO J O N E S , DAY, R E A V I S & P O G U E . NEWYORK 2300 TRAMMELL CROW CENTER 2001 R O S S A V E N U E M A I L I N G ADDRESS: P.O. BOX 6 6 0 6 2 3 DALLAS. TEXAS 7 5 2 6 6 CLEVELAND PARIS COLUMBUS PITTSBURGH FRANKFURT RIYADH GENEVA TAIPEI FACSIMILE: 2 1 4 - 9 6 9 . 5 1 0 0 HONG KONG TOKYO DIRECT DIAL NUMBER: IRVINE WASHINGT DALLAS. T E X A S 75201 TELEPHONE: 2 1 4 . 2 2 0 . 3 9 3 9 TELEX: 730852 CABLE: ATTORNEYS DALLAS 9846:joy 774710-046-014 (214) 969-2975 July 31, 1995 ..: Honorable Commissioner of Patents and Trademarks Box PA'l3NT APPLICATION Washington, D.C. 20231 Re: New Patent Application For: AUTOMATICALLY SWITCHED EQUALIZATION CIRCUIT Applicant: Daniel A. Palmer Attorney's Docket No.: 774710046014 Sir: Enclosed for filing are the following papers relating to the above-identified application for patent: 0 0 0 0 0 0 Specification, Claims and Abstract (25 pages) Declaration and Power of Attorney (5 pages) Informal Drawings (1 sheet) Check in the amount of $882.00 to cover the filing fee of the application (see below) Assignment with transmittal Check in the amount of $40.00 to cover the Assignment recordal fee DLMAIN Doc: 17352.1 Printed 07-31-95 14:11 i JON).,, DAY, R E A V I S & P O G U E .. Honorable Commissioner nts and Trademarks CLAIMS AS FILED NumberFiled Total Claims: Independent Claims: Mu1t . Dependent Claim: Basic Fee: Number Extra -0 - 16 (-20 =) 5 ( - 3 =) -2- Rate x22.00 x76.00 x240.00 Fee 152.00 $730.00 Total Filing Fee $ 882.00 Please file the application. All correspondence is to be directed to the Applicant's attorney at the address set forth in the Declaration and Power of Attorney for Patent Application. In the event the check(s) is inadvertently omitted or is insufficient, please charge the required fees to the Jones, Day, Reavis & P o p e Deposit Account 10-1202. Please credit any overpayment to Deposit Account 10-1202. A duplicate copy of this sheet is enclosed. Respectfully.submitted, A (gdiie E. Hall Reg. 0.24,099 "Express No. N B 437 361 441 Date of Deposit JULY 31. 1995 I hereby certify that this paper or service under 37 CFR 1.10on the D.C. 20231 JOY MONTOOTH nted name of person mailing DLMAIN Doc: 17352.1 Printed: 07-31-9514:11 States Postal Service "Express Mail Post Office to Addressee" to the Commissioner of Patents and Trademarks, Washington, ' .i .,* 710046014 ..*. 1 1 1 AUTOMATICALLY SWITCHED INVENTOR DANIEL A. PALMER "Express Mail" mailing label No. NB 437 361 441 Date of Deposit JULY 31, 1995 I hereby certlfy that this paper or fee is being deposited With the United States Postal Service "Express Mail Post Office to Addressee" service under 37 CFR 1.10 on the date indicated above and is addressed to the Commissioner of Patents and Trademarks, Washington, D.C. 2023 1 JOY MONTOOTH (Typed or printed name of person mailing - - (SYpaturk of person mailing paper or fee) DLMAIN Doc: 180792.1 .. 4 2 BACKGROUND OF THE INVENTION 1. FIELD OF THE INVENTION The present invention relates to equalization circuits in general and in particular to a circuit that enables the equalization of loudspeakers to be automatically switched when an optional subwoofer is added to an entry level two-speaker audio system. ‘IC-,.. DLMAIN Doc: 180792.1 , 3 2.DESCRIPTION OF RELATED ART When a pair of loudspeakers are designed for listening to music or any other program material, the equalization to those speakers is normally optimized for full range frequency operation, commonly 2OHz-2OkHz. Active and/or passive filters are required to obtain flat frequency response for full range operation 5 and these types of filters are commonly used in loudspeaker systems to correct for non-uniform frequency response. Transducers which are small and inefficient are not optimum for low frequency operation; however, due to cost considerations and/or lack of available space . inside smaller loudspeaker enclosures (such as multimedia speakers), these small transducers are 10 commonly used despite their relatively poor ability to reproduce low frequencies and despite limited power handling capacity. A 2.5 to 3 inch diameter transducer, for example, may only be effective down to 200 to 300Hz, whereas typical program material extends down to approximately 20Hz. These I smaller transducers are better suited as satellite speakers for handling mid to 15 high frequency program material. When a subwoofer is added to a loudspeaker system, the low frequency information in the program material will be handled by the subwoofer; however, if the smaller, less efficient transducers are still subjected to those same low frequencies and high excursion, they needlessly labor to reproduce 20 low frequencies, consuming excess power, causing the speaker to distort and causing the sound quality to be less than optimum. The system is not smart enough to know that the subwoofer has been connected. Thus, in the prior art, if a subwoofer is desired to be added to the system, a manually operated switch or switches must be used to change filters that are connected to the left 25 and right speakers and to route any signals to the subwoofer. DLMAIN Doc: 180792.1 . 4 . . V 4 SUMMARY OF THE INVENTION In the present invention, when an electrical connector is inserted into the subwoofer output jack, the insertion is sensed and automatically causes the necessary switches to be operated. The activation of the switching means causes the low frequency drive to the smaller satellite speakers to be 5 substantially reduced. This allows the satellite speakers (which are normally quite small and tend to be weak at low frequencies) to operate in the mid range and high frequency range for which they are best suited. In doing this, the power dissipation in the smaller satellite speakers is reduced dramatically due to the fact that they are no longer required to reproduce the low 10 frequencies that are being fed to the subwoofer. In many cases this is critical since a low-cost, low-current wall transformer is typically used to power the satellite amplifiers and therefore provides a limited supply voltage and current. Due to the loading of the power supply when the amplifier reproduces low frequencies, the available output power for mid and high frequencies is 15 substantially diminished thus causing distortion at all frequencies and inefficient use of the power supply. The result of the present invention is louder and clearer sounding satellite speakers exhibiting a much lower tendency to clip the amplifier signals driving them due to a significant decrease in low frequencies. 20 In the present invention, a stereo minijack with a DPDT switch is used at the subwoofer output jack or connector. When the subwoofer output jack or connector is unused (no plug inserted), the audio signal is caused by the DPDT switch in the jack to be routed such that full range frequencies are fed to the amplifier output sections and thence to the satellite loudspeakers. 25 When the subwoofer output jack is used (plug inserted), the audio signal is caused by the DPDT switch in the jack to be routed such that only mid range DLMAIN Doc: 180792.1 \ 5 and high frequencies are fed to the amplifier output sections and satellite speakers. The amplifiers and power supply for the satellite speakers are no longer subject to the low frequencies which will now be reproduced by the subwoofer through the plug inserted in the output jack. 5 Thus, in one condition, when the satellite speakers are being used by themselves, the equalization to the satellite speakers is optimized for full range operation and only the intended filters for full range operation are inserted into the circuit path. In the second state, when a subwoofer is added to the'-system and has a 10 connector inserted into the subwoofer output jack, a switch integrated into the subwoofer output jack causes the signals to be rerouted to appropriate.Nters that move the corner frequency of the high pass filters (-3dB point) out to a higher frequency. As stated previously, this allows the satellite speakers (which are normally quite small and tend to be weak at low frequencies) to operate 15 in the mid range and high frequency range where they are better suited. Thus, the power dissipation in the smaller satellite speakers is dramatically reduced due to the fact that they are no longer required to reproduce the low frequencies which are fed to the subwoofer that has been added to the system. As stated, the result is a louder and clearer sound from the satellite speakers 20 because they exhibit a much lower tendency to clip the signals from the amplifier driving them. Thus it is an object of the present invention to provide an automatically switched equalization circuit that allows fullrange frequency audio frequency signals to be coupled to a loudspeaker and which automatically couples only 25 mid and high frequency range audio signals to the loudspeaker when a woofer or low frequency audio loudspeaker is connected to the system. It is another object of the present invention to use an automatically switched equalization circuit with left and right audio channel loudspeakers. DLMAIN Doc: 180792.1 6 It is still another object of the present invention to modify an audio loudspeaker system utilizing a pair of mid and high frequency range speakers by adding a low frequency range speaker that automatically disconnects low frequency range signals from said pair of mid range to high frequency range 5 speakers. Thus the present invention relates to an automatically switched equalization circuit for an audio loudspeaker of the mid and high frequency ranges including audio input signals, a jack for receiving a connector that couples the audio signals to a low frequency range loudspeaker, a switch associated with 10 the jack having first and second positions, the first position of the switch coupling a full frequency range audio signal to the audio loudspeaker, the second position of the switch coupling a mid frequency range and high frequency range audio signal to the audio loudspeaker and the switch being in the first position when the low frequency range loudspeaker is unused and 15 being in the second position when the low frequency range loudspeaker is used and the connector is inserted in the jack. f I 7 BRIEF DESCRIPTION OF THE DRAWINGS These and other features of the present invention will be more fully disclosed when taken in conjunction with the following DETAILED DESCRIPTION OF THE DRAWINGS in which like numerals represent like elements and in which: 5 FIG. 1is a schematic diagram of the novel automatically switched equalization circuit; FIG. 2 is a schematic arrangement of a Hall effect switch that can be used as the switch that provides the automatic switching of the equalization circuit; FIG. 3 is a general diagram illustrating the use of an electronic device as the 10 switch for providing the automatic equalization; and FIG. 4 is a schematic arrangement of an optical device that can be used as the switch to provide the automatic equalization. 7 DLMAIN Doc: 180792.1 i I 8' DETAILED DESCRIPTION OF THE PRESENT INVENTION A two speaker audio system 10 is shown in FIG. 1and has audio inputs 12 and 14 feeding two channels 16 and 18 which may be left and right channels for the two-speaker system. The invention, however, would work with a single speaker as will be seen hereafter. Each of the left and right channels 16 and 5 18 has an input amplifier 20 and 22, respectively. They also have respective output amplifiers 24 and 26 which drive the'respective speakers 28 and 30. The audio signals, after being amplified by amplifiers 20 and 22 in each of the channels 16 and 18, are coupled to full range filters 32 and 36, respectively. A switching unit 40 has a switch 42 in the left channel that is coupled to 10 output terminal 58 of the full range filter 32 and couples the full range audio signals to amplifier 24 and thence to speaker 28. In like manner, in the right channel 18, the output of amplifier 22 is coupled to full range filter 36 whose output on terminal 60 is coupled through switch 44 to amplifier 26 that drives speaker 30. It is to be understood that when a pair of loudspeakers such as 15 28 and 30 in FIG. 1are designed for listening to music or any other program material, the equalization to those speakers is normally optimized for the full frequency range operation which is commonly 2OHz-2OkHz. The full range filters 32 and 34 are required to obtain flat frequency response in the full range operation and these types of filters are commonly used in loudspeaker 20 systems to correct for non-uniform frequency response. Transducers that are small and inefficient, and typically forming the loudspeakers 28 and 30, are not optimum for low frequency operation. However, due to cost considerations and/or lack of available space inside smaller loudspeaker enclosures, these small transducers are commonly used despite their relatively poor ability to 25 reproduce low frequencies and despite limited power handling capacity. Such a speaker may be a 2.5-3 inch diameter transducer and may be effective only DLMAIN Doc: 180792.1 9 down to 200-300Hz whereas typical program material extends down to approximately 20Hz. Thus these smaller transducers 28 and 30 are better suited as satellite speakers for handling mid to high frequency program material. As defined herein, mid to high frequency program material is 5 intended to mean the range of 200-2OkHz generally and in the preferred range of 300Hz to 20kHz. If it is decided to add a subwoofer to the loudspeaker system, such subwoofer would handle frequencies from ~OHZ-~OOHZ, the low frequency information in the program material. However, if the smaller, less efficient 10 transducers 28 and 30 are still subjected to these same low frequencies and high excursion, they needlessly labor to reproduce low frequencies, consume excess power, distort the audio signals, and cause the sound quality to be less than optimum. The system is not smart enough to know that the subwoofer has been added to the system. 15 In the present invention, if a subwoofer is desired to be added, a jack 48, which may be a stereo minijack, is coupled to the output of an amplifier 46 whose inputs are coupled to the audio sources 12 and 14. When a connector for the subwoofer is inserted into the output jack 48, it makes contact with terminals 50 and 52 to receive the audio frequency signals. It will 20 be sensitive primarily to the low frequency signals 20Hz-300Hz because of its construction. However the insertion of the connector into the jack 48 is sensed by a second arm 54 that is mechanically coupled to switches 42 and 44. Switches 42 and 44 are caused to move from their connection to output terminals 58 and 60 of the full range filters 32 and 36 to the output terminals 25 62 and 64 of the respective high pass filters 34 and 38. This allows the satellite speakers 28 and 30 (which, as stated previously, are normally quite small and tend to be weak at low frequencies) to operate in the mid range and high frequency range (300Hz-20kHz) for which they are better suited. In D L W N Doc: 180792.1 10 doing this the power dissipation in the smaller satellites 28 and 30 is reduced dramatically due to the fact that they no longer are required to attempt to reproduce the low frequencies now being fed to the subwoofer coupled to jack 48. In many cases, this is critical since a low-cost, low-current wall transformer 5 is typically used to power the satellite amplifiers and headroom in the enclosure is at a premium. The result of this automatic switching scheme therefore is louder and clearer sounding satellite speakers 28 and 30 that exhibit a much lower tendency to clip the amplifier signals from amplifiers 24 and 26 that drive them because there is a significant decrease in low 10 frequencies coupled to the loudspeakers 28 and 30. Thus, when the subwoofer output jack 48 is unused, that is, no plug is inserted therein, the audio signal is routed through the switches 42 and 44 such that full range frequencies from filters 32 and 36 are fed to the amplifier output sections 24 and 26 and thence to the satellite loudspeakers 28 and 30. 15 When the subwoofer output jack 48 is used and a plug or connector is inserted therein, switches 42 and 44 are then activated to cause the audio signal to be routed through the switches 42 and 44 such that only mid range and high frequencies (3OOHz-2OkHz) from high pass filters 34 and 38, respectively, are fed through the amplifier output sections 24 and 26 and 20 thence to the satellite speakers 28 and 30. The amplifiers 24 and 26 and the power supply for the satellite speakers are no longer subject to the low frequencies that will now be reproduced by the subwoofer. Therefore it can be seen that in the first state, when the satellite speakers 28 and 30 are used by themselves, the equalization to the speakers 25 28 and 30 is optimized for full range operation and only the intended filters 32 and 36 are inserted into the circuit path by switches 42 and 44. However, when a subwoofer is to be added to the circuit, and a connector is inserted into the jack 48, through the use of a switch integrated 4 .. . , 1 11 into the jack 48, the signal is rerouted to high pass filters 34 and 38 by switches 42 and 44 where 'the comer frequency (-3dB point) of the high pass filter is moved to a higher frequency. This allows the satellite speakers to operate as stated earlier in the mid range and high frequency range where they are better 5 suited. The low frequencies are fed to the subwoofer coupled to jack 48. Clearly the switches 40 shown in FIG. 1 are intended to be diagrammatic in representation and may take the form of a number of different types of switches. They may be mechanical switches as shown, all operated by the insertion of a connector in jack 48 in a well-known manner. 10 However, the switches could be magnetically operated as illustrated in FIG. 2. In FIG. 2, connector 54 is part of jack 48 shown in FIG. 1 and when a connector is inserted in the jack 48, connector 54 moves a magnet 66 in close association with a Hall effect device 68 which is in effect a switch that couples the filter output from the high pass filter 34, for example, as the input 15 to the loudspeaker amplifiers 24 or 26. In like manner, such a Hall effect switch could be operated in a reverse process. That is, it could disconnect the switch 42 from the full range filter 32 and switch 44 from full range filter 36. In FIG. 3, an electrical device is shown as the switch, or a portion of switch device 40. In FIG. 3, input arm 54 can be the same arm 54 shown 20 in FIG. 1in jack 48 and could supply a voltage through contact arm 72 to an electronic device such as a MOS transistor 74. Proper voltage is supplied to the MOS 74 at terminal 76. When the switch terminals 54 and 72 are closed, the MOS may be made either to conduct or nonconduct as desired. If it is to conduct, it could couple the high pass filter 34 output on terminal 78 to the 25 loudspeaker input on line 80 which would be coupled to the amplifiers 24 and 26, respectively, in their respective channels. One of such switches would be used to open the connection to the full range amplifier 32 and close the connection to the high pass filter 34. /I DLMAIN Doc: 180792.1 4 12 FIG. 4 illustrates a general optical circuit that could be used as the switches 40 in FIG. 1. Again, the arm 54 could be the arm 54 illustrated in FIG. 1which, when the woofer is added and the connector is inserted in jack 48, arm 54 is brought into contact with arm 82, thus supplying a voltage to a 5 light emitting device 84 which generates a light represented by arrow 86. This light activates a photoelectric device 88 causihg it to conduct and connect the input 90 to the output 92. The input 90 could be the output of the high pass filters 34 or 38 and the output 92 could be the input to the amplifiers 24 or 26 that drive the loudspeakers 28 and 30. Clearly the devices could be made to 10 operate in the reverse direction to disconnect a full range filter from the output amplifiers 24 and 26. One skilled in the art will understand how to use each of the circuits shown in FIGS. 2,3 and 4 to provide the proper switching arrangement 40. Thus there has been disclosed a novel automatically switched 15 equalization circuit where, when satellite speakers are being used by themselves and these speakers are small and inefficient and not optimum for low frequency operation and are suitable down to an effective frequency range of ~OO-~OOHZ, the equalization of the satellite speakers is optimized for full range operation and only the intended filters for full range operation are 20 inserted into the circuit path. However, when the connector is inserted into an output jack to connect a subwoofer to the system, a switch, integrated into the jack or associated with the jack, reroutes the audio signals to filters that move the corner frequency of the high pass filter (-3dB) out to a higher frequency. This 25 allows the satellite speakers (that are normally quite small and tend to be weak and low frequency) to operate in the mid-range and high frequency range (300Hz-20kHz) where they are better suited. In doing this, the power dissipation in the smaller speakers is reduced dramatically due to the fact that 13 they no longer are required to reproduce the low speakers now being fed to the subwoofer. The result is louder and clearer satellite speakers exhibiting a much lower tendency to clip the signals from the amplifier driving them. This becomes critical for a low-current wall transformer used to power the 5 satellite amplifiers which produces a limited supply voltage and currrent. Due to the loading of the power supply when the amplifier reproduces low frequencies, the available output power for mid and high frequencies is substantially diminished thus causing distortion at all frequencies and inefficient use of the power supply. 10 While the invention has been described in connection with a preferred embodiment, it is not intended to limit the scope of the invention to the particular form set forth, but, on the contrary, it is intended to cover such alternatives, modifications, and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims. DLh4AIN Doc: 180792.1 14 CLAIMS 1 2 . 3 1. An automatically switched equalization circuit for a set of left and right channel audio loudspeakers of the mid and high frequency ranges including: 4 left and right channel audio input signals; 5 6 a stereo jack for receiving a connector that couples the left and right 7 a switch associated with said stereo jack having first and second audio signals to a low frequency loudspeaker; positions; 8 said first position of said switch coupling a full frequency range audio 9 signal to the left and right channel loudspeakers; 10 11 said second position of said switch coupling only mid frequency and high 12 frequency audio signals to said left and right channel loudspeakers; 13 and 14 said switch being in said first position when said low frequency range 15 loudspeaker is unused and being automatically placed in said 16 second position when said low frequency range loudspeaker is used 17 and said connector is inserted into said stereo jack. /i' DLMAIN Doc: 180792.1 15 1 2 f\ An automatically switched equalization circuit as in claim 1further 2. including: 3 full frequency range filters for coupling said audio signal to said left and 4 right Q,eakers when said switch in said first position; and -c 1Ters /high pass 4 - k for ~ coupling said audio signals to said left and right 5 P loudspeakers when said switch in said second position. 6 A 1 2 A 2 An automatically switched equalization circuit as in claim dfurther 3. A including: 3 a first audio amplifier in each of said left and right audio channels for 4 amplifying said audio signals prior to being filtered by both said 4 dfrequency range filters and said high pass filters; and 5 F 6 a second audio amplifier in each of said left and right audio signal 7 channels prior to the corresponding left or right channel 8 loudspeakers for amplifying either the full range audio signals or 9 the high pass frequency audio signals as selected by said first and second switch positions. 10 1 2 1 2 1 2 /G 4. An automatically switched equalization circuit as in claim 1wherein said switch associated with said stereo jack is a Hall effect switch. 5. An automatically switched equalization circuit as in claim 1wherein said switch associated with said stereo jack is an electronic switch. 6. An automatically switched equalization circuit as in claim 1wherein said switch associated with said stereo jack is an optical switch. DLMAIN Doc: 180792.1 16 1 2 7. An automatically switched equalizationcircuit as in claim 1wherein said stereo jack is an miniature jack. DLMAIN Doc: 180792.1 . . , 17 0 1 8. In a loudspeaker system having at least one loudspeaker coupled 2 to an input audio signal through a full range audio frequency filter, the 3 improvement including: 4 5 6 7 a high pass filter having an input for receiving said audio input signal and having an output; an input connector for a low frequency loudspeaker, said input connector receiving said input audio signals; 8 a switch having an output coupled to said at least one loudspeaker and 9 having an input for selective coupling between said full audio 10 frequency range filter and said high pass filter output; and 11 switch control means coupled to said switch and operated by said low 12 frequency speaker input connector such that when a low frequency 13 speaker is connected to said input connector, said switch couples 14 only said high pass filter signals to said at least one loudspeaker. /- DLMAIN Doc: 180792.1 4 18 1 9. 2 A circuit for coupling left and right channel audio signals to a set of corresponding left and right loudspeakers, said circuit including: 3 a first input amplifier for each of said left and right channels for amplifylng said audio signals; an equalization circuit coupled to the output of each said first amplifiers in each of said left and right channels; 7 said equalization circuit providing both full range audio frequency output 8 signals and high pass audio frequency signals for each of said left 9 and right channels; 10 11 said left and right loudspeakers operating in the mid frequency to high frequency range; 12 a second amplifier having an input coupled to and receiving both of said 13 left and right channel audio signals and generating audio output 14 signals; 15 first and second single-pole double-throw switches, each switch having an 16 output terminal coupled to a corresponding left or right 17 loudspeaker and a first input terminal for receiving a corresponding 18 left or right full range audio frequency output signal from said 19 equalizer and a second input terminal for receiving a corresponding 20 left or right high pass audio frequency signal from said equalizer; 21 a supplemental low frequency loudspeaker conhector jack coupled to the 22 output of said second amplifier for receiving a low frequency 23 loudspeaker connector; and 24 switch control means coupled to said single-pole double-throw switches 25 and to said low frequency loudspeaker connector jack such that 26 when a low frequency loudspeaker connector is inserted in said 27 supplemental loudspeaker connector jack, said single-pole double- 28 throw switches are operated to couple only high pass filter signals DLMAIN Doc: 180792.1 . . I , i 19 29 to said first and second loudspeakers and when said low frequency 30 loudspeaker connector jack is not inserted in said supplemental 31 loudspeaker connector jack, said single-pole, double-throw switches 32 couple only full range audio frequency signals to said left and right 33 loudspeakers. 74 DLMAIN Doc: 180792.1 20 10. A loudspeaker system including: left and right channel audio signal input terminals; left and right loudspeakers generally suited for handling mid to high range audio frequencies; left and right full range filters, each having an input coupled to one of said left and right channel signal input terminals and an output normally coupled to its corresponding left or right loudspeaker; left and right high pass frequency filters, each having an output for 9 coupling to a corresponding one of said left and right loudspeakers 10 and having an input coupled to one of said left and right channel 11 signal input terminals; 12 a connector jack for a low frequency range loudspeaker being coupled to 13 said left and right channel audio input signal terminals, said 14 connector jack for receiving a low frequency range loudspeaker 15 mating connector; and 16 switch means coupled to said connector jack for automatically 17 disconnecting said left and right loudspeakers from said left and 18 right full range filters and coupling a corresponding one of said left 19 and right high pass frequency filter outputs to corresponding ones 20 22 of said left and right loudspeakers when a low frequency range loudspeaker mating connector is coupled to said connector jack so as to enable said left and right':loudspeakers to operate more 23 efficiently. 21 21 1 2 3 11. A loudspeaker system as in claim 10 wherein said switch means further includes: . a single-pole double-throw switch in each of said left and right audio channels; 4 5 said single-pole of each switch being connected to a corresponding one of said left and right loudspeakers; 6 A 7 one terminal of said double-poles of each switch being connected to a 8 corresponding one of said outputs of said full range filters; 9 the other terminal of said double-poles of each switch being connected 10 to a corresponding one of said outputs of said high pass frequency 11 filters; and e* 12 said single-pole ofhsaid switch being moved from said one of said double- 13 pole terminals to said other one of said double-pole terminals when 14 said low frequency range loudspeaker mating connector is coupled 15 to said connectorjack to automatically cause only audio frequencies 16 in the high pass range to be coupled to said left and right 17 loudspeakers and only low audio frequencies to be coupled to said 18 low frequency loudspeaker. 1 12. A loudspeaker system as in claim 11 further including an audio 2 amplifier coupled between each audio input terminal and each full range filter 3 and high pass filter. 1 2 13. A loudspeaker system ‘asin claim 10 wherein said switch means includes: 3 a Hall effect switch having an input coupled to the output of one of said 4 filters and an output coupled to a corresponding one of said left 5 and right loudspeakers; and /-.DLMAIN Doc: 180792.1 22 6 a magnet associated with said Hall effect switch and operated only when 7 said low range loudspeaker mating connector is inserted in said 8 connector jack to energize said Hall effect switch and effect the 9 connection between each said high pass filter and a corresponding left or right loudspeaker. 10 1 14. A loudspeaker system as claim 10 wherein said switch includes: 2 an MOS device having an input coupled to the output of one said filters 3 and output coupled to a corresponding one of said left and right 4 loudspeakers; a control bias connection coupled to said MOS device to operate said 5 MOS device; and 6 7 8 a bias voltage coupled through said connector to said control bias 9 coupling between said high pass filter and its corresponding left or 10 right loudspeaker only when said low frequency range loudspeaker 11 mating connector is inserted in said connector jack. connection such that said MOS device is operated to effect the said 15. A loudspeaker system as in claim 10 wherein said switch means includes: an optical device for each filter, each device having an input coupled to the output of one of said filters and an output coupled to a corresponding one of said left and right loudspeakers; a light source associated with each optical device for activating said optical device to effect the connection between said filter output at its corresponding left or right speaker; and 7.2 DLMAIN Doc: 180792.1 4 23 9 10 11 a power source coupled through said connector to control said light source only when low frequency range loudspeaker mating connector is inserted in said connector jack. I 24 1 2 16. An automatically switched equalization circuit for a single audio loudspeaker of the mid and high frequency ranges including: 3 audio input signals; 4 a connector jack for receiving a mating connector that couples the audio 5 signals to a low frequency range loudspeaker; 6 a switch associated with said connector jack and having first and second 7 input terminals and an output terminal coupled to said single audio 8 loudspeaker, said switch being operated between said input 9 terminals when said mating connector is inserted in said connector 10 11 12 jack; said first input terminal of said switch receiving a full frequency range of audio signals for the single audio loudspeaker; 13 said second input terminal of said switch receiving only a mid frequency 14 range and high frequency range of audio signals for said single 15 audio loudspeaker; and 16 said switch being coupled to said first terminal when said low frequency 17 range loudspeaker is unused and being coupled to said second 18 terminal when said low frequency range loudspeaker is used and 19 said mating connector is inserted in said connector jack. DLMAIN Doc: 180792.1 I 4 25 AUTOMATICALLY SWITCHED EQUALIZATION CIRCUIT A circuit in which, when loudspeakers are being used by themselves, the equalization to the loudspeakers is optimized for full range operation and only the intended filters for full range operation are inserted into the circuit path. When a subwoofer is added to the system to handle low frequencies, the 5 subwoofer mating connector is inserted into a connector jack to receive the audio signals and simultaneously inserts high pass filters into the circuit for the speakers so they operate in the mid range and high frequency range where they are better suited. The subwoofer handles and reproduces the low frequencies. The result is louder and clearer satellite speakers that exhibit a 10 much lower tendency to clip the signals from the amplifier driving them. 4 t No. 774710046014 PATENT OMBINED DECLARATION AND POWER OF ATTORNEY INAL, DESIGN, NATIONAL STAGE OF PCT, SUPPLEMENTAL, DIVISIONAL, CONTINUATION OR C-I-P) As a below named inventor, I hereby declare that: TYPE OF DECLARATION This declaration is of the following type: (check one applicable item below) X original 0 design . . o supplemental NOTE: If the declaration is for an International Application being filed as a divisional, continuation or continuationin-part application, do= check next item; check appropriate one of last three items. national stage of PCT 0 NOTE: If one of the following 3 items apply, then complete and also attach ADDED PAGES FOR DIVISIONAL, CONTINUATION OR CEP. divisional 0 , 0 continuation continuation-in-part (C-I-P) INVENTORSHIP IDENTIFICATION WARNING If the inventors are each not the inventors of all the claims, and explanation of the facts, including the ownership of all the claims at the time the last claimed invention was made, should be submitted. My residence, post office address and citizenship are as stated below next to my name. I believe I am the original, first and sole inventor (If only one name is listed below) or an original, first and joint inventor (If plural names are listed below) of the subject matter which is claimed and for which a patent is sought on the invention entitled TITLE OF INVENTION AUTOMATICALLY SWITCHED EQUALIZATION CIRCUIT DLMAIN Doc: 183214-1 1 (4 @) NOTE: (4 x 0 is attached hereto. was filed on as Serial No. 08/ or 0 Express Mail No., as Serial No. not yet known and was amended on (if applicable). Amendments filed after the original papem are deposited with the PTO which contain new matter are not accorded a filing date by being referred to in the declaration. Accordingly, the amendments involved are those filed with the application papers or, in the case of a supplemental declaration, are those amendments claiming matter not encompassed in the original statement of invention or claims. See 37 CFR 1.67. 0 was described and claimed in PCT International Application No. filed on and as amended under PCT Article 19 on (if any). ACKNOWLEDGEMENT OF REVIEW OF PAPERS AND DUTY OF CANDOR I hereby state that I have reviewed and understand the contents of the above identified specification, including the claims, as amended by ahy amendment referred to above. I acknowledge the duty to disclose information X which is material to patentabilityas defined in 37, Code of Federal Regulations, 6 1.56 (also check the following items, if desired) 0 and which is material to the examination of this application, namely, information where there is a substantial likelihood that a reasonable examiner would consider it important in deciding whether to allow the application to issue as a patent, and 0 In compliance with this duty there is attached an information disclosure statement in accordance with 37 CFR 1.98. PRIORITY CLAIM (35 U.S.C. 0 119) I hereby claim foreign priority benefits under Title 35, United States Code, 6 119 of any foreign application(s) for patent or inventor’s certificate or of any PCT international application(s) designating at least one cou&y other than the United States of America listed below and have also identified below any foreign application(s) for patent or inventor’s certificate or any PCT international application(s) designating at least one country other than the United States of America filed by me on the same subject matter having a &g date before that of the application(s) of which priority is claimed. DLMAIN Doc: 183214-1 2 t (complete (d) Qr (e)) no such applications have been filed. (d) X (e) 0 . NOTE: such applications have been filed as follows. Where item(c) is entered and the International Application which designated the US. itself claimed priority check item (e), enter the details below and make the priority claim. FILED A. PRIOR FOREIGN/PCT APPLICATION(S) WITHIN 12 MONTHS (6 MONTHS FOR DESIGN) PRIOR TO THIS APPLICATION AND ANY PRIORITY CLAIMS UNDER 35 U.S.C. 0 119 COUNI'RY (OR INDICATE IF PCT) APPLICATION NUMBER DATE OF FILING (day, month, year) PRIORITY CLAIMED UNDER 37 USC 119 ALL FOREIGN APPLICATIONS(S), IF ANY FILED MORE THAN 12 MONTHS (6 MONTHS FOR DESIGN) PRIOR TO THIS U.S. APPLICATION NOTE: If the application filed more than 12 months from the fding date of this application is a P(JT filing forming the basis for this application entering the United States as (1) the national stage, or (2) a continuation, divisional, or continuation-in-part,then also completeADDED PAGES TO COMBINED DECLARATION AND POWER OF AlTORNEY FOR DMSIONAL, CONTINUATION OR GI-P APPLICATION for benefit of the prior US. or PCT application(6) under 35 U.S.C. 5 120. POWER OF ATTORNEY I hereby appoint the following attorney(s) and/or agents(s) to prosecute this application and transact all business in the Patent and Trademark Office connected therewith. (List name and registration number) ID Alfred E. HdJReg. No. 24.099LRobert W. Turner (Reg. No. &l& ); John I P. Pinkerton (Reg. No. 28,7466; Mark N. Reiter (Reg. No. 35 78 Ronald A. Antush htenK nT % K $ e$' R. Adamo Ross Spencer Garsson (Reg. -. DLMAIN Doc: 183214-1 3 (check the following item, if applicable) 0 Attached as part of this declaration and power of attorney is the authorization of the above-named attorney(s) to accept and follow instructions from my representatives(s). SEND CORRESPONDENCE TO DIRECT TELEPHONE CALLS TO: (Name and telephone number) Pome & - Dallas, Texas 75201 .c Alfred E. Hall (214) 969-2975 . DECLARATION I hereby declare that all statements made herein of my own knowledge are true and that all statements made on information and belief are believed to be true; and further that these statements were made with the knowledge that willful false statements and the like so made are punishable by fine or imprisonment, or both, under Section 1001of Title 18 of the United States Code, and that such willful false statements may jeopardize the validity of the application or any patent issued thereon. SIGNATURE(S) NOTE: Carefully indicate the family (or last) name as it should appear on the filing receipt and all other documents. Full name of sole or first inventor - DANIEL A. PALMER Inventor's signature Date - 7-20 - Country of Citizenship U.S.A. Residence 3328 AMARILLO AVENUE, SEMI VALLEY, CALIFORNIA 93063 Post Office Address SAME AS RESIDENCE DLMAJN Doc: 183214-1 4 x . ..: 4 ; L I . CHECK PROPER BOX(=) FOR ANY OF THE FOLLOWING ADDED PAGE(S) WHICH FORM A PART OF THIS DECLARATION ' - . . ,e.';\ 0 Signature for fourth and subsequent joint inventots. 'Number of t .* . " ** -*. .. ., . .. 7 ' h ' s::, /' ;/ Signature by administrator(trk), executor(trix) or legal ..ceprtsentative for deceased or incapacitated inventor. Number of pages added \*$s, 0 *** 0 Signature for inventor who refuses to sign or cannot be reached by person authorized under 37 CFR 1.47. Number of pages added *** 0 Added page for signature by one joint inventor on behalf of deceased inventor(s) where legal representative cannot be appointed in time (37 CFR 1.47). *** Added pages to combined declaration and power of attorney for divisional, continuation, or continuation-in-part (C-I-P) application. I7 Number of pages added *** 0 Authorization of attorney(s) to accept and follow instructions from representative. *** (If no further pages from a part of this Declaration, then end this Declaration with this page and check the following item:) X This declaration ends with this page. DLMAIN Doc: 183214-1 5 ... i t - " L O & PATENT In The United States Patent and Trademark OFce In re Application of DANIEL A. PALMER Serial No.: 08/509,160 Filed: JULY 31, 1995 For: AUTOMATICALLY SWITCHED EQUALIZATION CIRCUIT Group Art Unit: Examiner: 2608 UNKNOWN -1 HONORABLE COMMISSIONER OF PATENTS AND TRADEMARKS Washington, D.C. 20231 Attention: APPLICATION PROCESSING DIVISION'S CORRECTION BRANCH Dear Sir: REQUEST FOR CORRECTED FILING RECEIPT Attached is a copy of the official FILING RECEIPT showing the error thereon. Please provided a corrected FILING RECEIPT. Respectfully submitted, AY, REA September 20, 1995 2300 Trammell Crow Center 2001 Ross Avenue Dallas, TX 75201 (214) 969-2975 DLMAIN Doc: 188477.1 Printed 09-20-95 1503 & POGUE JmL& - AlfrefE. Hall Reg. No. 24,099 ATTORNEYS FOR APPLICANT I i 08/509,160 07/31/95 2608 $882.00 774710046014 . ALFRED E HALL , ::'/: . JONES DAY REAVIS AND POGUE 2300 TRAMMELL CROW CENTER 2001 ROSS AVENUE DALLAS .TX 75201 Receipt Is acknowledged of this nonpro rswltdof the examlnstbn. Be wm to. INVENTION when lnquhg about thls a of the Qta~ pmssnted on this receipt. Clatonwr Comcdlon Bnmh wWn 10 APPllcm4 FOREIGN FILING LIC TITLE AUTOMATICALLY SWITCHED EQUALIZATI PRELIMINARY CLASS:'381 ... -c (see reverse) . 1 ' 16 5 a . I . I Attome. Paper: 1 Client: . ... . Alfred E; H a l i Request for Corrected F i l i n g Receipt Due: Date: 9120195 S.N.: . . - 08/509,160 Harman File: 774710-046-014 Title: AUTOMATICALLY SWITCHED EQUALIZATloN C i R C U I T Inventor: Palmer Check Filed in the United States Patent Office on I 4 PATENT k /./-t-T ---, In The United States Patent and Trademark Ofice DANIEL A. PALMER 08/509,160 Serial No.: . Filed: JULY 31, 1995 For: AUTOMATICALLY SWITCHED EQUALIZA'TlON CIRCUIT Group Art Unit: Examiner: 2608 UNKNOWN HONORABLE COMMISSIONER OF PATENTS AND TRADEMARKS Washington, D.C. 20231 Attention: APPLICATION PROCESSING DIVISION'S CUSTOMER CORRECTION BRANCH SECOND REQUEST FOR CORRECTED FILING RECEIPT 1. Attached is a copy of the official filing receipt received from the PTO in the above application for which issuance of a corrected filing receipt is respectfully requested. 2. There is an error with respect to the following data which is: X incorrectly entered and/or 0 omitted. ERROR IN 1. X Applicant's name 2. 0 Applicant's address 3. 0 Title 4. 0 Filing Date 5. 0 Serial Number 6. 0 Foreign/PCT Application Re: 7. 0 Other DLMAIN Doc: 196429-1 Printed 01-05-961134 c CORRECT DATA 1. 2. 3. 4. 5. 6. 7. Daniel A. Palmer e -.. ._ . -. ..- . . -.. . c 3. (complete the following applicable item A or B) A. X The correction(s) is/are not due to any error by applicant and no fee is due. OR B. At least one of the above corrections is due to applicant’s error and the fee therefor under 37 CFR 1,19(h) of $25.00 is paid as follows: 0 Enclosed is check for $25.00. 0 Charge Deposit Account $25.00. 4. Also enclosed is a copy of the return postcard showing receipt of the first Request for a Corrected Filing Receipt by the Mailroom on September 9, 1995 and to date we have had no response. Respectfully submitted, January 5, 1996 2300 T r a m e l l Crow Center 2001 Ross Avenue Dallas, TX 75201 (214) 969-2975 Reg. No! 24,099 ATTORNEYS FOR APPLICANT DLMAIN Doc: 196429-1 Printed: 01-05-9611:34 -2- ~~~ ~ ’ 4 UNITED STATES I ARTMENT OF COMMEPCE Patent and Trademark Office ASSISTANT SECRE'iARY AND COMMISSIONER OF PATENTS AND TRADEMARKS PTO- 103X (Rev. 8-96) ._ FILING RECEIPT ALFRED E HALL JONES DAY REAVIS AND POGUE 2300 TRAMMELL CROW CENTER 2001 ROSS AVENUE DALLAS, TX 75201 Receipt 1s acknowledged of this nonprovislonal Patent Application. It will be considered In its order and you will be notified a8 to the results of the examlnatlon. Be sure to provide the U.S. APPLICATION NUMBER, FILING DATE, NAME OF APPLICANT, and TITLE OF INVENTION when Inquiring about thla application. Fees trensmitted by check or draft are subject to collectlon. Plesse verify the accuracy of the data presented on this receipt, If an error Is noted on this Filing Receipt, please wrlte to the Application Proceasing Dlvlsion's Customer Correction Branch within 10 days of receipt. Please provide e copy of the Filing Receipt with the change8 noted thereon. Applicant(s) A A. PALMER, SEMI VALLEY, CA. FOREIGN FILING LICENSE GRANTED 09/13/95 TITLE AUTOMATICALLY SWITCHED EQUALIZATION CIRCUIT PRELIMINARY CLASS: 381 (see reverse) UNITED STATES DEPARTMENT OF COMMERCE Patent and Trademark Office Address: COMMISSIONER OF PATENTS AND TRADEMARKS Washington, D. C. 2023 1 ISER~ALNUMBER I FILING D A T E I I FIRST NAMED A P P L I C A N T A T T O R N E Y D O C K E T NO. 1 r All participants (applicant, applicant's representative, PTO personnel): 6 [Srf Date of interview Type: plephonic --- -- 0 Personal (copy i s given to Exhibit shown or demonstration conducted: Agreement s@ Claimsdiscussed:- 0 Yes applicant P o . 0epplicant's &resentative). If yes. brief description: reached with respect to some or all of the claims in question. 2, / / Identifieation of prior art discussed: 0 was not reached. Description of the general nature of what was agreed t o if an agreement was reached. or any other comments: U (A fuller description, if necessary, and a copy of the amendments. if auailable. which the examiner agreed would render the claims allowable must be attached. Also, where no copy of the amendments which would render the claims allowable i s available, a summary thereof must be attached.) Unless the paragraphs below have been checked to indicate to the contrary. A FORMAL WRITTEN RESPONSE TO THE LAST OFFICE ACTION I S NOT WAIVED AND MUST INCLUDE THE SUBSTANCE OF THE INTERVIEW (e.9.. items 1-7 on the reverse side of this form). If a response to the last Office action has already been filed, then applicant is given one month fmm this interview date t o provide a statement of the substance of the interview. It is not necessary for applicant to provide a separate record o f the substance of the interview. 0 Since the examiner's interview summary above (including any attachments) reflects a compte requirements that may be present in the last Office action, and since the claims are now allow response requirements of the last Office action. F'TOL4:3 (REV 1-84) Examiner's Signature .OWIGINAC FOR BMSERT10N IN RIGHT HAND FLAP OF FlL'E WRAPPER ections, rejections and onsidered to fulfill the UNITED STATES DEPARTMENT OF COMMERCE Patent and Trademark Office Address: COMMISSIONER OF PATENTS AND TRADEMARKS Washington, D.C. 20231 DATE MAILED: NOTICE OF ALLOWABILITY L PART 1. 1. p h i s communication is responsive t 2. %All RlTS IS (OR REMAINS) CLOSED in this application. If not included the claims being allowable, PR herewith (or previously mailed), a Notice Of Allowance And Issue Fee Due or other appropriate communication will be sent in due 3. $h":o ,'wed 4. 5. claims are /-/L are acceptable. 0 The drawings filed on 0 Acknowledgment is made of the claim for priority under 35 U.S.C. 119. The received. I.-] been filed in parent application Serial No. certified copy has , filed on 1-1 been received. [-1 not been 6.vNote the attached Examiner's Amendment. 7. W N o t e the attached Examiner Interview Summary Record, PTOL-413. 8. 0 Note the attached Examiner's Statement of Reasons for Allowance. 9. 0 Note the attached NOTICE OF REFERENCES CITED, PTO-892. 10. 0 Note the attached INFORMATION DISCLOSURE CITATION, PTO-1449. PART II. A SHORTENED STATUTORY PERIOD FOR RESPONSE 10 comply with the requirements noted below is set t o EXPIRE THREE MONTHS FROM THE "DATE MAILED indicated on this form Failure to timely comply will result in the ABANDONMENT of this application Extensions of time may be obtained under the provisions of 37 CFR 1 136(a) 1 2 0 Note the attached EXAMINER'S AMENDMENT or NOTICE OF INFORMAL APPLICATION, PTO-152. which discloses that the oath or declaration is deficient A SUBSTITUTE OATH OR DECLARATION IS REQUIRED PAPPLICANT MUST MAKE THE DRAWING CHANGES INDICATED BELOW IN THE MANNER SET FORTH ON THE REVERSE SIDE OF THIS PAPER 0 Drawing informalities are indicated on the NOTICE RE PATENT DRAWINGS, PTO-948. attached hereto or to Paper No CORRECTION IS REQUIRED has been approved by the examiner CORRECTION IS b 0 The proposed drawing correction filed on REQUIRED c 0 Approved drawing corrections are described by the examiner in the attached EXAMINER'S AMENDMENT CORRECTION IS REQUIRED d )&Formal drawings are now REQUIRED a Any response to this letter should include in the upper right h a i d corner, the following information from the NOTICE OF ALLOWANCE AND ISSUE FEE DUE: ISSUE BATCH NUMBER. DATE OF THE NOTICE OF ALLOWANCE, AND SERIAL NUMBER. Record PTOL- 413 easons for Allowance - Notice of References Cited PTO-892 Information Disclosure Citation PTO-1449 PTOL-37 (REV. 4-89] * - Notice 01 lnlormal Application. PTO-152 Notice re Patent .Drawings. PTO-948 Listing of Bonded Draltsmen -'Other ' i -2- Serial Number: 08/509,160 Art Unit: 2608 1. An Examiner's Amendment to the record appears below. Should the changes and/or additions be unacceptable to applicant, an amendment may be filed as provided by 37 C.F.R. § 1.312. To ensure consideration of such an amendment, it MUST be submitted no later than the payment of the Issue Fee. . Authorization for this Examiner's Amendment was given in a telephone interview with Mr. Hall on June 5, 1996. The a plication has been amended as follows: Claim 9 line 5, delete ''a'' and change "filter" to --filters-- / line 1, change "1" to - - 2 - - * , Claim 3 / line 5, insert -- full-- before "frequency". Claim 11, line l d n s e r t --each-- after ''of" (first occurrence) . 2. Any inquiry concerning this communication or earlier communications from the examiner should be directed to Examiner Isen whose telephone number is (703) 305-4386. FORESTER W. ISEH PRIMARY EXAMINER ART UNIT 2@lY3 TO SEPARATE, HOLD TOP AND BOTTOM EDGES, SNAP-APART AND DISCARD CARBON FORM PTO-892 (REV. 2-92) No' U.S. DEPARTMENT O F COMMERCE PATENT A N D T R A D E M A R K O F F I C E q557Yy/60 bRoUp ATTACHMENT TO PAPER NUMBER &crr APPLICANT[S) NOTICE OF REFERENCES CITED U.S. PATENT DOCUMENTS I I DOCUMENTNO. I DATE I I I SUBCLASS CLASS F I L I N G D A T E IF APPROPRIATE 25 I23 FOREIGN PATENT DOCUMENTS -~ DOCUMENTNO. I DATE I VERT I N E N T COUNTRV I I OTHER REFERENCES (Including Author, Title, Date, Pertinent Pages, Etc.) R S -. U . * A copy of this reference is not being furnished with this office action. (See Manual of Patent Examining Procedure, section 707.05 (a).) DATE DUE BEEN EXAMINED AND ISALLOWED FOR ISSUANCE AS A PATENT. THE-ISSUE FEE MUST BE PAID WITHIN THREE$MONTHSFROM THE MAILING DATE OF THIS NOTICE OR THIS APPLICATION SHALL BE REGARDED AS ABANDONED.' THIS STATUTORY PERIOD CANNOT BE EXTENDED. , I HOW TO.RESPOND TO THIS NOTICE: I. Review the SMALL ENTITY Status shown above. If the SMALL ENTITY is shown as YES, verify your current SMALL ENTITY status: A. If the status is changed, pay twice the amount of the FEE DUE shown above and notify the patent and Trademark Office of the change in status, or B. If the Status is the same, pay the FEE DUE shown above. If the SMALL ENTITY is shown as NO: ' A. Pay FEE DUE shown above, or B. File verified statement of Small Entity Status before, or with, - pay of. 1/2 the FEE DUE shown above. mark Office (PTO) with your ISSUE FEE. It. Part B of this notice should be completed and returned to the Patent and T Even if the ISSUE FEE has already been paid by charge to deposit account, Part B should be completed and returned. If you are charging the ISSUE FEE to y ould also be completed and returned. I l l . All communications regarding this applic , serial number and batch number. Please direct all communication prior to 'IMPORTANT REMINDER: Patents issu maintenance fees. I fees when due. require payment of nsibility to ensure timely payment of maintenance ' . PATENT 774710046014 In The United States Patent and Trademark Office In re Application of DANIEL A. PALMER Serial No.: 08/509,160 Filed: JULY 31, 1995 For: AUTOMATICALLY SWITCHED EQUALIZATION CIRCUIT Group Art Unit: Examiner: 2608 F. ISEN ASSISTANT COMMISSIONER FOR PATENTS BOX ISSUE FEE Washington, D.C. 2023 1 - ' u M By: Dear Sir: TRANSMITTAL, OF FORMAL DRAWINGS In response to the NOTICE OF ALLOWABILITY mailed on June 11, 1996, attached please find: the formal drawing(s) for this application. Number .of Sheets: 1 each sheet of drawing indicates the identifying indicia suggested in 9 1.84(c) on the reverse side of the drawing. Respectfully submitted, JO@ August 12, 1996 2300 Trammel1 Crow Center 2001 Ross Avenue Dallas, TX 75201 (214) 969-2975 DLMAIN Doc: 196429-1 Printed: 08-12-9611:ll cC, 03 I)repebycertifythatthis CorresPondence is being dtoday with the United States 2; ;ro i'? Postal Service as first class G 3 Ir: mail in an envelope a d d r e s s e e : s q R r E G U E A'TTORNEYS FOR APPLICANT .. \-- 5581626 FIG. I 547 66 VSO * < . ' l r ' FILTER OUTPUT I V i 74 76 80 m MOS . BIAS FIG. 3 LOUDSPEAKER INPUT 78 FILTER OUTPUT vs FILTER OUTPUT F l G. 4 LOUDSPEAKER INPUT I .' *.. ... .... dence is being deposited with the United States Postal first class mail in an envelope addressed to: 1 . . ... . . . . Y Nbte: .If this:certificate of .m,ailingisused;.it:can on1y.b used to transmit the .Issue Fee. . ~ i ~ ~ e ~ i ~ ~ ~ . ~ ~ ~ ~ s . paper; such.as.anassignment or formal'dmkii . . ~ ~ ~ ? . . . . ~ . t Paper Number The Commissioner of Patents and Trademarks , , j Has received an applicationfor a paten'tfor a new and useful invention. The title and description of the invention are enclosed. The requirementsof law have been complied with, and it has been determined that a patent on the invention shall be granted under the law. Therefore, this United States Patent Grants to the person(s) having title to this patent the riglit to exclude others from mking, using, offering for sale, or selling the invention throughout the United States of America or importing the invention into the United States ofAmerica for the term setforth belorv, subject to the paymertt of niuiritenance fees as provided by law. I f this application was filed prior to June 8, 199:, the term of this patent is rhe longer of seventeen years from the date of grant of this patent or twenty yearsfim the earliest effective U.S. jifing date of the application, subject to any statutory extension. If this application was filed on or after June 8,1995, the term of this patent is twenty years from the earliest effective US.filing date of the application, subject to any statutory extension. L- Cornrni&oner oJPurenrs and Trademarkt Form PTO-1584 (qev. 5/96) . ... ........... . .-.-a ..... . .- . . . e . . ~ ..... . . . PATENT APPLICATION SERIAL NO. 08/509160 U. S. DEPARTMENT 'OF COMEERCE PATENT AND TRADEMARK OFFICE FEE RECORD SHEET 240 AH 08/28/95 08509160 882.00 CK 774710046014 1 101 PTO-1556. (5/87) ' I . .- 6 FORM PTO-875 (Rev. 10/94) Patent and Trademark Office, U.S. DEPARTMENT OF COMMERCE \ . , INDEX OF CLAIMS SYMBOLS ................................. ................................. Rejected Allowed (Through nurnberal) Canceled + ................................. RaStrlcted N ................................. Non-elected I ................................. Interference A ................................. Appeal 0 ................................. Objected J P SEARCHED Class Sub. Date Exmr. SEARCH NOTES Date INTERFERENCESEARCHED Class Sub. I Date I Exmr. I Exmr.