EP0412725A2 - Tonwiedergabegerät - Google Patents

Tonwiedergabegerät Download PDF

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Publication number
EP0412725A2
EP0412725A2 EP90308534A EP90308534A EP0412725A2 EP 0412725 A2 EP0412725 A2 EP 0412725A2 EP 90308534 A EP90308534 A EP 90308534A EP 90308534 A EP90308534 A EP 90308534A EP 0412725 A2 EP0412725 A2 EP 0412725A2
Authority
EP
European Patent Office
Prior art keywords
delay
signal
phase
reproduction apparatus
sound reproduction
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP90308534A
Other languages
English (en)
French (fr)
Other versions
EP0412725A3 (en
Inventor
Seiichi Ishikawa
Ryoh Tagami
Tomio Shiota
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Panasonic Holdings Corp
Original Assignee
Matsushita Electric Industrial Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Matsushita Electric Industrial Co Ltd filed Critical Matsushita Electric Industrial Co Ltd
Publication of EP0412725A2 publication Critical patent/EP0412725A2/de
Publication of EP0412725A3 publication Critical patent/EP0412725A3/en
Withdrawn legal-status Critical Current

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04S—STEREOPHONIC SYSTEMS 
    • H04S5/00—Pseudo-stereo systems, e.g. in which additional channel signals are derived from monophonic signals by means of phase shifting, time delay or reverberation 
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04S—STEREOPHONIC SYSTEMS 
    • H04S1/00—Two-channel systems
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04S—STEREOPHONIC SYSTEMS 
    • H04S3/00—Systems employing more than two channels, e.g. quadraphonic
    • H04S3/02—Systems employing more than two channels, e.g. quadraphonic of the matrix type, i.e. in which input signals are combined algebraically, e.g. after having been phase shifted with respect to each other

Definitions

  • the present invention relates to an apparatus for reproducing sound with the use of left and right or upper or lower loudspeakers, e.g. a car audio system, a stereo-sound audio system such as a portable cassette player, and a video/sound reproduction system having upper and lower loudspeakers disposed upper and lower sides of the center of a video screen for reproduction of a center channel signal, and more particularly, a sound reproduction apparatus for use in a TV receiver having left and right loudspeakers provided on the left and right of a TV screen.
  • a car audio system e.g. a car audio system, a stereo-sound audio system such as a portable cassette player, and a video/sound reproduction system having upper and lower loudspeakers disposed upper and lower sides of the center of a video screen for reproduction of a center channel signal
  • a sound reproduction apparatus for use in a TV receiver having left and right loudspeakers provided on the left and right of a TV screen.
  • a prior art television receiver with a built-in loudspeaker system comprises, as shown in Fig.3, an audio signal input terminal 10a, power amplifiers 3a and 3b for amplifying the input signals, left and right loudspeak­ ers 4a and 4b arranged to be actuated by the amplified input signals, a TV tube 11 for reproduction of a TV image, and a cabinet 12 accommodating the loudspeakers, TV tube, and other audio and video signal circuit boards.
  • the video signal to be reproduced may be a TV picture signal modulated from a normal broadcasting signal or a video signal supplied from the outside
  • the audio signal supplied to the built-in sound reproduction apparatus may be an audio signal modulated in synchronization with the TV picture signal or an audio signal supplied from the outside.
  • the video and audio signals are to be reproduced simultaneously or sepa­rately.
  • Fig.4 illustrates how two impulse reproduced waveforms generated from the left and right loudspeakers are combined at the points A and B respectively.
  • the character­istic of propagation at the point A is shown in Fig.4-c and at the point B in Fig.4-d, in which a form of distortion is present resulting from a time lag. More particularly, the distortion is associated with the fact that sounds from the two loudspeakers reach the listening point with time lag, i.e. a comb filter is developed in the sound space.
  • a comb filter is developed in the sound space.
  • upper and lower extra loudspeakers for having a stereo image at the center of the TV screen may enable to give a sweet spot when the listening point is equally spaced from both the upper and lower loudspeakers.
  • the listening point is either higher or lower like dislocated leftwardly or rightwardly, a distortion in the propagation also occurs and causes the reproduced sound to be degraded in quality.
  • a sound reproduc­tion apparatus comprises a signal input terminal for receiving an input audio signal, a delay signal generator consisting mainly of a filter for blocking a low-tone component of the input audio signal and a delay means for delaying the output signal from the fil­ter, an in-phase adder for summing an output signal of the delay signal generator and the input audio signal, an oppo­site-phase adder for summing the output signal of the delay signal generator in reverse phase and the input audio sig­nal, power amplifiers for amplifying output signals of the in-phase and opposite-phase adders respectively, and a pair of left and right or upper and lower loudspeakers for being actuated by the amplified signals.
  • the delay signals from the left and right loudspeakers are offset by each other at a listening point lying on the center line of a TV receiver thus not to appear in the form of sound.
  • Sounds derived from the signals which have not passed through the delay signal generator will propagate by the same time from the left and right loud­speakers, causing no distortion in the propagation.
  • the delay signal is actuated so that the distortion of propaga­tion caused by a difference in the propagation time of sound can be compensated for improvement.
  • the flat range of propagation characteristics will be extended from the center line to both the left and right sides, thus increasing the audible area of reproduced sound at accept­able quality.
  • Fig.1 illustrates a sound reproduction apparatus ac­cording to one embodiment of the present invention.
  • An object of this embodiment is to increase an audible area of quality sound.
  • a signal input terminal 10a for input of an audio signal
  • a low cut-off filter 1a for blocking the low-tone level of the input audio signal
  • a linear phase delayer 1b for giving a time delay in every frequency of an output signal from the low cut-off filter
  • a delay signal generator 1 for summing an output signal of the delay signal generator 1 and the input audio signal from the signal input terminal 10a
  • an opposite-phase adder 2b for summing the output signal of the delay signal generator 1 in reverse phase and the isniut audio pgnal from the signal input terminal 10a
  • power ampli­fiers 3a and 3b for amplifying the output signals of the in-phase and opposite-phase adders 2a, 2b, respectively
  • left and right loud-speakers 4a and 4b provided for being actuated by the amplified signals from the amplifiers 3a and 3b, respectively.
  • Figs.2-a and 2-b schematically illustrate the impulse response of sounds generated from the right and left loud­speakers 4a and 4b, in which like Fig.4, the impulses repro­duced by the left and right loudspeakers are combined in the waveform at each of the points A and B explained in Fig.3, exhibiting a form of impulse response.
  • Fig.2-c shows the propagation characteristic at the point A while Fig.2-d at the point B.
  • the signal reproduced by the left loudspeaker 4b is fed from the opposite-phase adder 2b where a signal passing the low cut-off filter 1a is added and thus, remains undecayed in the low band. Accordingly, the reproduction of low-tone sound is ensured and no difference in the energy of sound between the left and right loudspeakers will be sensed. This means that the flat range of propagation characteristic is extended from the center line to both the left and right sides, increasing the audible area of reproduced sound with acceptable quality.
  • the delay time and the cut-off setting frequency of the low cut-off filter 1a are deter­ mined by the distance between the left and right loudspeak­ers, the listening distance, and the listening angle. If the delay is too long, the direct sound and the delayed sound are heard separately and if too short, the propagation characteristic will be less improved. Preferably, when the distance between the two loudspeakers is about 0.2 to 2 meters, the delay time may be within a range from 1 to 20 mm/sec. Also, if the low cut-off frequency is too high, the improvement will decline and if too low, the low band of an output signal from the opposite-phase adder means 2b will be decreased, causing a difference in the reception of sound energy between left and right. Preferably, the low cut-off frequency may be about 50 to 500 Hz.
  • the delay signal generator 1 may have the two components 1a and 1b substituted in the order of arrangement with equal success.
  • the low cut-off signals are delayed and then, reproduced in both the normal and reverse phase by the left and right loudspeakers together with the direct signals, whereby the flat range of propagation char­acteristic can be extended from the center line to both the left and right sides, increasing the audible area of repro­duced sound with acceptable quality.
  • Fig.5 illustrates a sound reproduction apparatus show­ing another embodiment of the present invention.
  • An object of this embodiment is to increase the audible area of quality sound derived from a central normal-position signal during the reproduction of 2-channel stereo signals.
  • an input signal adder 2c for summing input stereo signals supplied from two signal input terminals 10a and 10b and an attenuator 2d for attenuating the output signal of the adder 2c to a half.
  • the common signals existing in both the left and right channels are normal-position signals to be reproduced in the center, offering the same effect as of monophonic signals when reproduced by the left and right loud speakers.
  • the center sound when received at a location off the center line exhibits a dis­tortion in the propagation and will thus be declined in quality.
  • the monophonic signal generated by summing signals with the input signal adder 2c is delayed by a delay signal generator 1 and after reversed in phase, added to left and right signals by an in-phase adder 2a and an opposite-phase adder 2b respectively, the receipt of quality sound will be feasible at an off-center location during the reproduction of stereo signals, as well as the previous embodiment.
  • the central normal-position signal of the output of the input signal adder 2c which is generated by summing the left and right signals has an amplitude of 2 times the center signal component of the left or right signal.
  • the output of the input signal adder 2c is preferably reduced by the signal attenuator 2d to about 1/2 in the amplitude.
  • Fig.6 illustrates a sound reproduction apparatus show­ing a further embodiment of the present invention.
  • An object of this embodiment is to increase the audible area of quality sound derived from a central normal-position false-source signal, which is associated with the allocation of center-channel signal to the left and right loudspeakers, during the reproduction of front 3-channel audio signals.
  • a demodulator 5 for converting input stereo signals fed from two signal input terminals 10a and 10b into 4-channel ster­eophonic signals, a power amplifier 3c for amplifying a signal to be reproduced at the rear, and a loudspeaker drive signal output terminal 4c for delivering a drive signal to a rear loudspeaker 4d.
  • the center-channel signal is fed to a delay signal generator 1 and also, to both in-phase and opposite-phase adders 2a and 2b where the signals are added together with the outputs of the delay signal generator 1 to the left- and right-channel signals respectively prior to amplification.
  • the receipt of quality sound from the center-channel signal will also be possible at a location off the center line between two main loudspeakers, ensuring a wide audible area of stereo sound.
  • Fig.7 illustrates a sound reproduction apparatus show­ing a still further embodiment of the present invention.
  • An object of this embodiment is to decrease the re­verse-phase effect of sound which is encountered during the reproduction of two delay signals in opposite phase with their respective left and right loudspeakers.
  • the low cut-off filter 1a can be replaced with equal success by a band-pass filter adapted for rejecting a high band signal. It is preferred to have the high cut-off frequency ranging from 1 to 10 KHz.
  • Fig.8 illustrates a sound reproduction apparatus show­ing a still further embodiment of the present invention.
  • An object of this embodiment is to carry out the repro­ duction of sound throughout a wide rage of frequencies in which no separation between direct sound and delayed sound is caused in the entire frequency band.
  • a non-linear phase delayer for providing a delay time varying with fre­quency.
  • Fig.9-a shows an analog circuit of a basic component of the non-linear phase delayer 1c provided in the form of a primary full-wave pass filter. Its delay time is shown in Fig.9-b which will be decreased when the frequency is high and increased when low. A number of the circuits having different time constant (CR) from each other are coupled in series forming an array so that the delay frequency charac­teristic is properly determined providing a delay as shown in Fig.10-a.
  • Fig.11-a illustrates a waveform of impulse response in the non-linear phase delayer 1c, in which the lower the frequency, the longer the delay time.
  • the non-­linear phase delayer 1c may be composed of secondary full-­wave pass filters so that the natural angular frequency ⁇ o becomes greater in the delay time characteristic introducing a time delay shown in Fig.10-b.
  • Fig.12 illustrates a sound reproduction apparatus showing a still further embodiment of the present invention, in which a linear phase delayer 1b and a nonlinear phase delayer 1c are coupled to each other in series.
  • the impulse response after an in-phase adder 2a involves the sum of time delays of the two delayers as a time delay of the delay signal which follows the input audio signal.
  • Figs.13 and 14 show sound reproduction apparatuses explaining further embodiments of the present invention in which denoted by 1aO to 1aN are bandpass filters for sepa­rating an input audio signal into an N-number of frequency bands.
  • the band signals are delayed by linear phase delay­ers 1bO to 1bN (Fig.13) or linear phase delayers 1b0 to 1bN and non-linear phase delayers 1cO to 1cN (Fig.14).
  • the characteristic of time delay in the embodiment of Fig.13 is shown in Fig.10-c and that of Fig.14 in Fig.10-d.
  • the separation between the direct sound and the delayed sound is reduced by decreasing the time delay, as described in Embodiment 1.
  • a proper time delay is needed for a distortion in the propagation to be corrected.
  • the delay should be small when the frequency is high and large when low.
  • the delay time can be set short when the frequency is high and long when low.
  • the delay is determined in length and frequency by the distance between the left and right loudspeakers, the listening distance, and the listening angle.
  • the delay may be preferably 2 to 20 mm/sec at a frequency of about 200 Hz, 1 to 10 mm/sec at about 500 Hz, 0.5 to 5 mm/sec at about 1 KHz, 0.3 to 3 at about 2 KHz, 0.1 to 1 mm/sec at about 5 KHz, and 0.05 to 0.5 mm/sec at about 10 KHz.
  • Figs.15 and 16 illustrate sound reproduction appara­tuses showing still further embodiments of the present invention.
  • An object of this embodiment is to decrease the re­verse-phase effect of sound which is encountered during the reproduction of two delay signals in opposite phase with their respective left and right loudspeakers.
  • a linear phase delayer 1bO As shown in Figs.15 and 16, there are provided a linear phase delayer 1bO and a non-linear phase delayer 1cO.
  • each sound reproduction apparatus having such an arrangement, two signals in opposite phase from the delay signal generator 1 are not directly reproduced by the left and right loudspeakers. More particularly, one of the two signals is further delayed a bit by the delayer 1bO or 1cO, so that the reverse-phase effect of sound can be re­duced during reproduction.
  • Fig.17 illustrates a sound reproduction apparatus showing a still further embodiment of the present invention.
  • An object of this embodiment is to ensure the optimum receipt of sound by selectively determining a difference in the propagation time from the left and right loudspeakers to the listening position with relation to the listening posi­tion and the distance between the two loudspeakers.
  • linear phase delayers 1b0 and 1b1 having different delay characteristics from each other, a delay signal selector 1d for selecting an output signal from either the first delayer 1b0 or the second delayer 1b1, and a delay selector control terminal 13 for receiving a signal for control of the delay signal selector 1d.
  • the introduction of a control signal to the delay signal selector control terminal 13 is selectively carried out by a listener so that the delay signal from the first delayer 1b0 or the second delayer 1b1 can be accepted at the listening position more naturally and effectively.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Stereophonic System (AREA)
EP19900308534 1989-08-05 1990-08-02 Sound reproduction apparatus Withdrawn EP0412725A3 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP20337489 1989-08-05
JP203374/89 1989-08-05

Publications (2)

Publication Number Publication Date
EP0412725A2 true EP0412725A2 (de) 1991-02-13
EP0412725A3 EP0412725A3 (en) 1991-10-09

Family

ID=16472975

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EP19900308534 Withdrawn EP0412725A3 (en) 1989-08-05 1990-08-02 Sound reproduction apparatus

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EP (1) EP0412725A3 (de)
JP (1) JPH03163999A (de)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0714222A2 (de) * 1994-11-26 1996-05-29 BECKER GmbH Pseudostereoschaltung für mobilen Rundfunkempfänger
US5617478A (en) * 1994-04-11 1997-04-01 Matsushita Electric Industrial Co., Ltd. Sound reproduction system and a sound reproduction method
US5844993A (en) * 1995-01-25 1998-12-01 Victor Company Of Japan, Ltd. Surround signal processing apparatus
US5892831A (en) * 1995-06-30 1999-04-06 Philips Electronics North America Corp. Method and circuit for creating an expanded stereo image using phase shifting circuitry
US5974153A (en) * 1997-05-19 1999-10-26 Qsound Labs, Inc. Method and system for sound expansion
US6373954B1 (en) * 1997-10-14 2002-04-16 Cirrus Logic, Inc. Single-chip audio circuitry, method, and systems using the same

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5692050A (en) * 1995-06-15 1997-11-25 Binaura Corporation Method and apparatus for spatially enhancing stereo and monophonic signals

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4151369A (en) * 1976-11-25 1979-04-24 National Research Development Corporation Sound reproduction systems
GB2074823A (en) * 1980-03-12 1981-11-04 Cohen J M Stereophonic audio reproduction system
US4394536A (en) * 1980-06-12 1983-07-19 Mitsubishi Denki Kabushiki Kaisha Sound reproduction device
EP0142213A1 (de) * 1983-11-17 1985-05-22 Koninklijke Philips Electronics N.V. Gerät zur Erzeugung eines pseudo-sterophonen Signals
GB2180727A (en) * 1985-09-12 1987-04-01 Sgs Microelettronica Spa Non-recursive system for expanding the stereo base of stereophonic acoustic diffusion apparatus
US4841573A (en) * 1987-08-31 1989-06-20 Yamaha Corporation Stereophonic signal processing circuit

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS619100A (ja) * 1984-06-25 1986-01-16 Hitachi Ltd モノ−ラルのカラオケシステム
JPS63292800A (ja) * 1987-05-25 1988-11-30 Nippon Columbia Co Ltd 音像拡大形成装置
JPH01220600A (ja) * 1988-02-27 1989-09-04 Fujitsu Ten Ltd 車室内音場構成方式

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4151369A (en) * 1976-11-25 1979-04-24 National Research Development Corporation Sound reproduction systems
GB2074823A (en) * 1980-03-12 1981-11-04 Cohen J M Stereophonic audio reproduction system
US4394536A (en) * 1980-06-12 1983-07-19 Mitsubishi Denki Kabushiki Kaisha Sound reproduction device
EP0142213A1 (de) * 1983-11-17 1985-05-22 Koninklijke Philips Electronics N.V. Gerät zur Erzeugung eines pseudo-sterophonen Signals
GB2180727A (en) * 1985-09-12 1987-04-01 Sgs Microelettronica Spa Non-recursive system for expanding the stereo base of stereophonic acoustic diffusion apparatus
US4841573A (en) * 1987-08-31 1989-06-20 Yamaha Corporation Stereophonic signal processing circuit

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5617478A (en) * 1994-04-11 1997-04-01 Matsushita Electric Industrial Co., Ltd. Sound reproduction system and a sound reproduction method
EP0714222A2 (de) * 1994-11-26 1996-05-29 BECKER GmbH Pseudostereoschaltung für mobilen Rundfunkempfänger
EP0714222A3 (de) * 1994-11-26 1998-10-14 BECKER GmbH Pseudostereoschaltung für mobilen Rundfunkempfänger
US5844993A (en) * 1995-01-25 1998-12-01 Victor Company Of Japan, Ltd. Surround signal processing apparatus
US5892831A (en) * 1995-06-30 1999-04-06 Philips Electronics North America Corp. Method and circuit for creating an expanded stereo image using phase shifting circuitry
US5974153A (en) * 1997-05-19 1999-10-26 Qsound Labs, Inc. Method and system for sound expansion
US6373954B1 (en) * 1997-10-14 2002-04-16 Cirrus Logic, Inc. Single-chip audio circuitry, method, and systems using the same

Also Published As

Publication number Publication date
EP0412725A3 (en) 1991-10-09
JPH03163999A (ja) 1991-07-15

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