EP1341394A1 - Elektronische Vorrichtung zur Verarbeitung eines Audioisignals - Google Patents

Elektronische Vorrichtung zur Verarbeitung eines Audioisignals Download PDF

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Publication number
EP1341394A1
EP1341394A1 EP02290472A EP02290472A EP1341394A1 EP 1341394 A1 EP1341394 A1 EP 1341394A1 EP 02290472 A EP02290472 A EP 02290472A EP 02290472 A EP02290472 A EP 02290472A EP 1341394 A1 EP1341394 A1 EP 1341394A1
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EP
European Patent Office
Prior art keywords
signal
output terminal
output
dac
analog
Prior art date
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Granted
Application number
EP02290472A
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English (en)
French (fr)
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EP1341394B1 (de
Inventor
Kok Joo Lee
Guoliang Sun
Hon Gay Siew
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THOMSON LICENSING
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Thomson Licensing SAS
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R3/00—Circuits for transducers, loudspeakers or microphones
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04S—STEREOPHONIC SYSTEMS 
    • H04S3/00—Systems employing more than two channels, e.g. quadraphonic
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R3/00—Circuits for transducers, loudspeakers or microphones
    • H04R3/12—Circuits for transducers, loudspeakers or microphones for distributing signals to two or more loudspeakers

Definitions

  • the present invention relates to an electronic device for processing a digital audio signal, such as a player/recorder for CD's, DVDs or other types of digital storage media.
  • Such an electronic device is known e.g. from JP 8-088 892 A.
  • This prior art device has a digital/analog-converter (DAC) for converting a digital audio signal into an analog signal, first and second output terminals outputting said analog signal to sound generating devices, a detector for detecting whether a sound generating device is connected to the first output terminal or not and a control circuit for setting the power of the analog signal to a predetermined value according to whether a sound generating device is detected at the first output terminal or not.
  • DAC digital/analog-converter
  • the output power from the DAC is not adequate for the device connected to the second output terminal.
  • the resulting noise may startle or even cause pain to the user.
  • the object of the invention is, therefore, to provide an electronic audio signal processing device having two output terminals for connecting different types of sound generating devices, capable of controlling the power of an analog output signal according to whether a sound generating device is connected to one of the output terminals or not, in which there is no risk of an excessive volume being output when a sound generating device has been connected or disconnected, which is inexpensive and achieves a high fidelity of reproduction.
  • the analog signal thus generated can be a mono or stereo signal.
  • the detector will detect the device connected to the first output terminal, preferably the headphone, and the sound generating device connected to the second output terminal, in general the loudspeakers, will be muted by the switch. Thus, it is no longer necessary to disconnect the sound generating device from the second terminal.
  • the DAC By providing two output terminals for the analog output signal from a single DAC, and setting a characteristic of this analog signal according to the sound generating device detected, the DAC can be put to a double use, and the cost of the device can be reduced relative to a signal processing device requiring a dedicated DAC for each of its output terminals.
  • the characteristic thus set is the amplitude of the analog signal, i.e. the volume.
  • spectral characteristics of the analog signal might be set according to the sound generating device detected.
  • the first DAC has a reference input for inputting a reference signal, the level of which is to be set by a user, and the amplitude of the analog output signal delivered by the first DAC is proportional to the level of said reference signal. In this way, control of volume is possible directly at the DAC.
  • the device further comprises at least one second DAC for converting at least one second digital audio signal into an analog signal, a third output terminal for outputting said analog signal, said first and second digital signals forming a set of digital signals for simultaneous reproduction, and the switch is muted to disable output from each third output terminal, too, when a sound generating device is detected to be connected to the first output terminal.
  • An electronic device of this type is particularly adapted for processing a so-called Surround signal.
  • a so-called Surround signal is composed of up to six individual signal components referred to as Front L, Front R, Center, Subwoofer, Surround L and Surround R, each of which is to be output by one loudspeaker and requires a specific DAC for converting. If one of these DACs is used for generating an analog signal for output by a headphone, the loudspeaker corresponding to this DAC can no longer be supplied with the appropriate signal, so that the set of Surround signal components becomes incomplete. Under these circumstances, generating no sound at all at the loudspeakers is preferable over outputting a "mutilated" Surround signal.
  • the electronic device is for processing a Surround signal one might simply choose a dominant component of this multi-component signal such as the Front L or Front R signals for supplying them to the headphones in appropriately analog-converted form.
  • the device comprises a digital signal transformation circuit for converting the Surround signal components into a conventional stereo signal and to supply this stereo signal to the first DAC for conversion and to apply the thus converted signal to the headphone.
  • Figs. 1 to 3 each show a block diagram of an electronic device according to various embodiments of the present invention.
  • the device shown in Fig. 1 has an input terminal 1 to which a digital storage device such as a DVD drive, not shown, is connected. From the storage device, the input terminal 1 receives a digital audio Surround signal comprising six digital component signals, namely "Front Left”, “Front Right”, “Surround Left”, “Surround Right”, “Center” and “Subwoofer”.
  • a digital audio Surround signal comprising six digital component signals, namely "Front Left”, “Front Right”, “Surround Left”, “Surround Right”, “Center” and “Subwoofer”.
  • Three DACs 2, 3, 4 have their inputs connected to the input terminal 1. Each of them receives two components of the input signal, namely "Surround Left", “Surround Right” in case of DAC 2, “Center” and “Subwoofer” in case of DAC 3 and "Front Left” and “Front Right” in case of DAC 4.
  • Each of the DACs 2, 3, 4 has two outputs for outputting an analog-converted signal derived from the two digital
  • the outputs of DAC 4 are connected to a first output terminal 11 via a pair of amplifiers 7', and they are connected to a second output terminal 12 via a pair of amplifiers 7 and a pair of switches 8.
  • the outputs of DACs 2, 3 are connected to third output terminals 12' via a pair of amplifiers 7 and switches 8.
  • each switch 8 open or closed
  • a control unit 9 The state of each switch 8, open or closed, is governed by a control unit 9 according to detection results of a detector 10.
  • This detector 10 is located at a first output terminal 11 for detecting whether a headphone jack (not shown) is inserted in terminal 11 or not.
  • control unit 9 concludes that there is no headphone connected and holds the switches 8 of DACs 2, 3, 4 closed, so that the amplified output signals of these DACs are present at the second and third output terminals 12, 12', respectively. If a headphone jack is detected, the control unit 9 opens all switches 8, thus disabling the second and third output terminals 12, 12'.
  • Each of the DACs 2, 3, 4 has a reference level input for receiving a reference signal defining the output voltage range of the DACs.
  • Reference level inputs of DACs 2, 3, 4 are connected to a same reference level output of control unit 9 via line 14.
  • This line 14 may be a dedicated line on which only the reference signal is transmitted. If so, the reference signal can be an analog signal that is held at a first level by the control unit 9 whenever a headphone jack is detected by detector 10, and is held at a second level when no headphone jack is detected.
  • One or both of these levels can be fixed, can be set by a manufacturer, or, preferably, can be set by a user operating on input means, not shown, of the control unit 9.
  • the levels may be settable independently from one another, so that a listener can arbitrarily assign a value for both of them, or they may be in a certain proportional relationship, so that when the user specifies one of these, the control unit obtains the other by multiplying with a certain factor.
  • the factor is selected such that the volume experienced by a listener using headphones will be approximately the same as the volume experienced when using loudspeakers. Thus, there is no need for a listener to adjust the volume of the device when switching from loudspeakers to a headphone and vice versa.
  • the factor may also be settable by a user.
  • the line 14 may be part of a bus on which control information is exchanged between the control unit 9 and the DACs.
  • the reference signal is digital and can assume two values that can be stored in a memory of control unit 9 and can be fixed or settable as described above.
  • the analog signal available at the first output terminal comprises the Front Left and Front Right components of the Surround signal.
  • FIG. 2 A second embodiment is shown in Fig. 2. Components of this embodiment that are identical with those of the first embodiment described above are assigned the same reference numerals and are not described again.
  • a digital signal transformation circuit 5 has its input connected to input terminal 1.
  • the transformation circuit 5 receives all component signals of the Surround signal, and it mixes these to form a conventional digital stereo signal referred to as the "Downmix" signal which is supplied to a further DAC 6.
  • the DAC 6 is identical in design to DACs 2, 3, 4. Its two outputs provide a conventional analog stereo signal derived from the "Downmix” signal.
  • the outputs of DAC 6 are connected to first inputs of a multiplexer 15. Second inputs of multiplexer 15 receive the "Front Left” and “Front Right” component signals of the digital Surround signal.
  • the multiplexer 15 is controlled by control unit 9 to forward the "Front Left” and “Front Right” component signals to DAC 4 when no headphone jack is detected by detector 10. Under these circumstances, all six component signals of the Surround signal are present at the output terminals 12 and 12'.
  • the digital stereo signal from signal transformation circuit 5 is forwarded to DAC 4.
  • the output terminals 12, 12' are all disabled by switches 8, and an analog-converted conventional stereo signal is present at the first output terminal 11.
  • a third embodiment of the invention is shown in Fig. 3. It comprises all components of the second embodiment and, in addition, a further DAC 6 connected to the output of signal transformation circuit 5 and supplying a conventional analog stereo signal to a fourth output terminal 13 via amplifiers 7 and switches 8'. These switches 8' may be controloled by control unit 9 in the same way as switches 8 of the first and second terminals 12, 12' or independently from these.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Stereophonic System (AREA)
  • Circuit For Audible Band Transducer (AREA)
EP02290472.6A 2002-02-27 2002-02-27 Elektronische Vorrichtung zur Verarbeitung eines Audioisignals Expired - Lifetime EP1341394B1 (de)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP02290472.6A EP1341394B1 (de) 2002-02-27 2002-02-27 Elektronische Vorrichtung zur Verarbeitung eines Audioisignals

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP02290472.6A EP1341394B1 (de) 2002-02-27 2002-02-27 Elektronische Vorrichtung zur Verarbeitung eines Audioisignals

Publications (2)

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EP1341394A1 true EP1341394A1 (de) 2003-09-03
EP1341394B1 EP1341394B1 (de) 2016-12-28

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6958722B1 (en) * 2004-06-11 2005-10-25 Texas Instruments Incorporated SAR ADC providing digital codes with high accuracy and high throughput performance
EP1758428A1 (de) * 2004-06-04 2007-02-28 Matsushita Electric Industrial Co., Ltd. Akustische signalverarbeitungsvorrichtung
CN102413402A (zh) * 2010-09-26 2012-04-11 康佳集团股份有限公司 一种音频输出设备的音频控制方法和音频输出设备

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5161198A (en) * 1991-05-15 1992-11-03 Allied-Signal Inc. Mobile radio audio system
EP0659029A2 (de) * 1993-12-16 1995-06-21 GRUNDIG E.M.V. Elektro-Mechanische Versuchsanstalt Max Grundig GmbH & Co. KG Einrichtung zum Umschalten eines Lautsprechers
JPH0888892A (ja) * 1994-09-16 1996-04-02 Sony Corp 電子機器の制御装置
JPH11162574A (ja) * 1997-11-27 1999-06-18 Canon Inc プラグ識別装置

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5161198A (en) * 1991-05-15 1992-11-03 Allied-Signal Inc. Mobile radio audio system
EP0659029A2 (de) * 1993-12-16 1995-06-21 GRUNDIG E.M.V. Elektro-Mechanische Versuchsanstalt Max Grundig GmbH & Co. KG Einrichtung zum Umschalten eines Lautsprechers
JPH0888892A (ja) * 1994-09-16 1996-04-02 Sony Corp 電子機器の制御装置
JPH11162574A (ja) * 1997-11-27 1999-06-18 Canon Inc プラグ識別装置

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN vol. 1996, no. 08 30 August 1996 (1996-08-30) *
PATENT ABSTRACTS OF JAPAN vol. 1999, no. 11 30 September 1999 (1999-09-30) *

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1758428A1 (de) * 2004-06-04 2007-02-28 Matsushita Electric Industrial Co., Ltd. Akustische signalverarbeitungsvorrichtung
EP1758428A4 (de) * 2004-06-04 2010-06-23 Panasonic Corp Akustische signalverarbeitungsvorrichtung
US6958722B1 (en) * 2004-06-11 2005-10-25 Texas Instruments Incorporated SAR ADC providing digital codes with high accuracy and high throughput performance
CN102413402A (zh) * 2010-09-26 2012-04-11 康佳集团股份有限公司 一种音频输出设备的音频控制方法和音频输出设备

Also Published As

Publication number Publication date
EP1341394B1 (de) 2016-12-28

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