JPS58189808A - Disc reproducer - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION OBJECTS AND BACKGROUND OF THE INVENTION The present invention relates to a disc playback device, and more specifically, to an improved audio system used in a record playback device such as a video disc playback device. This invention relates to an erasing (muting) device.

the audio 2 and video signals are recorded on separate FM carriers;
A format of video record has been proposed in which the audio and video signals are reproduced by each FM demodulator in a video disk player.

Keizer U.S. Patent No. 397206
No. 4 discloses a playback device with a monophonic audio converter for playing monaural records. Palmer et al. U.S. Pat. No. 3969'
In the specification of No. 756, there is shown a playback device equipped with a stereo two-language playback function, and a pair of blind voice demodulators are connected to this playback device.

Under certain circumstances, it may be desirable to mute the audio output signal of a video disc playback device. U.S. Pat. No. 4,286,290 to Byres et al. describes the playback device's pause (PAUS E), loading (LO)
AI) ), during each operation mode period of set meal (5CAN),
The audio cancellation circuit is shown activated to prevent the noise λ generated by the audio demodulator from reaching the output of the playback device during such #1 operation mode. Pyles et al.
A. L. Baker) U.S. Pat. No. 40176'77
As is well known from the specification, it is shown that the sound can be canceled by supplying a squelch signal to the limiter stage of the FJi tuner.

Mr. Fox (Fax) US Patent No. 4119812
No. 4,221,930 to Okuno', a search (trunk) and hold circuit coupled to the output of an audio demodulator is disclosed.

It is shown that when a defect in a record is encountered, a holding operation mode in which the crunching or bouncing sound in the audio output signal is suppressed is activated by a single press.

The advantage of using a trunk-hold circuit is that it can provide both noise suppression and sound cancellation in a video disc playback device. Regarding monaural video tape playback equipment with these features, please refer to R-Run-A.
JS, which was published in 1980 by the Corporation.
Ianu to ET Player Technical
alJ Chapter 5, pages 35 to 38. The trunk-and-hold circuit of the playback device normally operates in tracking mode, but if a defect in the audio 1/'M carrier is detected, or if there is something missing in the audio signal Kr/'i. Switches to holding operation mode.

Examples other than +1 + cow (PLAY) are pause and search (S) f
flAf+Cll), during the operation mode period (mJ) such as loading, when the audio signal for I history is not normally taken out from the record, K is used to send the audio cancellation signal by the control microgrossenosa of the playback device. lj4 is generated.

The output of the trunk-and-hold circuit is applied to a television modulator along with the processed video signal to produce an RP output signal for use in conventional television receivers.

This invention relates to a problem that becomes more pronounced when the audio output of a conventional video disc playback device such as those described above is supplied to a high fidelity audio device rather than to a television receiver for playback. be. In particular, high-fidelity devices that generally have superior low frequency response performance tend to increase low frequency transient disturbances in audio signals. Despite the advantages of track-and-hold audio canceling devices, they cannot completely eliminate certain types of audio transients, referred to as turn-on and turn-off transients. It's not satisfying. As the name suggests, such a transient state is generated by the audio demodulation circuit of the playback device when the operating power supply of the playback device is turned on or turned off. has an amplitude significantly greater than the normal voice signal level and exceeds the dynamic range of the track plow hold circuit.
1 dragon nature or something.

The problem of turn-on and turn-off transients is exacerbated in playback devices in which additional processing is performed during demodulation, such as amplification, decoding of stereo signals, decompression, etc. In particular, additional processing circuits, including amplifiers, tend to exhibit turn-on and turn-off transients produced by demodulation circuits, making the attenuation characteristics required for speech cancellation circuits impractical. Make it as large as possible.

This invention has improved resistance to turn-on and turn-off transient characteristics. It is compatible with the zero-ho of the video disc playback device I have.

~Summary of the Invention> A disc playback device implementing this invention is a
The variable conditioner is conditioned to act as a signal stretcher or fixed gain amplifier under one operating condition and as an attenuator during selected other operating conditions of the playback device. It has gain amplification means.

This playback device is intended for use with several types of video e-records. One type of record is a recording of monogrammatic content on a single-FM carrier. Another format is that the stereo content is recorded in the form of a matrix with the L+R stereo sum signal on one FM carrier and the L-R stereo difference signal on the other FM carrier. The third type is.

The languages of the two countries are recorded in a matrix format, with each word or 70 loggrams being recorded with a separate FM carrier wave pressure. This type of recording format was introduced in 1981.
U.S. Patent Application No. 248', filed March 30, 2013
No. 776 (Japanese Patent Application No. 5'7-49926, Japanese Unexamined Patent Publication No. 57-1989)
17a51o'j't) has the advantage of being compatible with existing monaural video disc playback devices, as detailed in the specification of 17a51o'j't). Furthermore, for stereo records.

It is assumed that the sum and difference signals are compressed before being supplied to the recording frequency modulation circuit during disk mask fabrication. This is explained in the specification of U.S. Pat. When the demodulated stereo signal is IIM-order decoded and decompressed in the playback device, a favorable signal-to-noise ratio can be obtained.

11 Description of Examples> The present invention will now be explained in detail with reference to Sections F and 1.

The playback device has a power on/off switch 101 for controlling the supply of AC power voltage (AC power) to the power supply unit 12, which in turn controls the supply of AC power voltage (AC power) to the processing circuit of the F)4 device. supply pressure (DC output). The student unit 14 is equipped with a turntable for rotating a video disc record 181 and a menu converter transducer 20 for reproducing information recorded from the record. For purposes of explanation, this device records information in the form of phase (topology) changes and senses by sensing capacitance changes between the transducer 20 and the transducer 18. Alternatively, the record and transducer could be of optical type, and it is assumed that the audio signal is recorded in the format previously described.

The output of transducer 20 is coupled to the human power of Pick-Anoff transducer 22, and in response to the capacitance between the stylus in transducer 20 and the record to be played, a recorded signal containing video and audio carriers is generated. Generates FMM force signals representing information.

Circuits suitable for providing capacitance storage format records and the capacitance-to-voltage conversion function of converter 22 are well known. KoiK
For example, Mr. Stanley (T.O.

U.S. Pat.
ive Information&cords and
Playback Apparatus There
Foye)J.

U.S. patent of Mr. Keizer (E, 0. Keizer), title of the invention: Apparatus and Methods for Reproducing Apparatus and Methods for Color Video/Audio Records.
for Playback (Co1or Pict
ure / 5ound Records) J
, U.S. Patent No. 3,711,541 to R.C. Palmer, entitled ``Speed Regulator
(Velocity Adjusting System
') Details are given in J.

The 1"M output signal of converter 22 is sent to video processor 2.
4 manpower is supplied. This video f0rosesosa24
It includes a video frequency bandpass filter, demodulator, and conversion circuitry to produce a bandpass video output 1tA'4 in standard television formats such as NTSC or PAL. For such a 70 processor, an example is given for a preferred NTSC standard processor by Christopher T.J.

Christopher) and Mr. Wilba (J.
A, Wi Iber) US special, f1. No. 424786
No. 6, U.S. Patent No. 43 to J.G. Amery showing a PAL standard processor.
You can fully understand the content by looking at 142'73%. The audio portion of the F'M signal is processed as will be explained later and together with the unprocessed video 16 is supplied to a VCTV modulator 26, which modulator 26 contains the R, F and audio components. The output terminal 28 VC is supplied to the output signal, and is further supplied to the antenna of a normal television receiver. Suitable for use as a television modulator 26, selectively - ”Create and select
7'cTV channel (for example channel 3 or 4)
) is an integrated circuit that generates a reliable output.
Nat 1ona lSem1conductor
There is a model IJ1889N television video modulator manufactured by Company, Inc.

A control unit (based as an alternative to a surrogate device with random logic) coupled to the playback unit 14 and the processor 24 and a microphone (preferably a Kobro sensor) can e.g. - It has various control functions including the radial position of the transducer 20, the downward rotation movement, and the squelch of the video output signal of the 7'o setter 24. Control (2) Squelch signal generated by the unit 30 (SQ),
Voice erasure believe! (AM') is also supplied to terminals SQ and A M K of the processing circuit of the playback device.

A user-energized switch 41N is coupled to the human power of the unit 30 to initiate the operating mode functions of the reproducing device, such as up/down, residue regeneration, pause, and scan. When one of the user-energized switches in switch unit 32 is closed, control unit 30 addresses its internal read-only memory (ROM) and performs the desired control function. calls the appropriate sequence of instructions present in . For example, in the pause or fast scan mode, control unit 30 generates video squelch SQ and audio cancellation AM signals and also provides stylus lift + to transducer 20. The audio cancellation frequency AM (as shown in the figure [low level when f=j) is emitted in all operating modes of the playback device other than the playback operating mode) 30fr, it is 0. A track error correction signal generated from the field identification data signal extracted from the blade is applied to the transducer 20VC. The control unit 30 is shown in U.S. Pat. No. 43085'7'7 to Dieterich C.B.
It can be of any kind. It can also be combined with a processing unit 24 as shown in U.S. Pat.

A baseband audio signal Sl is obtained from the disk 18 by feeding the output of the converter 22 through a respective bandpass filter 40.42 to a pair of FM demodulators 44.46.

S2 is played. The center frequency of the audio carrier is preferably selected to correspond to an odd multiple of % of the line frequency, as proposed in Balmer, US Pat. No. 3,969,756. For example, for an NT S C standard playback device, filters 40 and 42 each have a center frequency of 715 Kf (z) and 905 KHz, and their bandwidths correspond to the first and second order of the modulated audio carrier. It is made somewhat wider than the peak shift of the audio carrier to ensure that sideband components can pass through.

The package a14 device 44.46 also exceeds the normal limit F M
It includes a defect detector 2 which generates respective defect indicating signals S3, S4 (low level pulses when activated as shown) in response to signal parameters (e.g. phase, amplitude). A suitable fcFM demodulator for this device is, for example, the FM 5IGNAL M Signal Postmodulator with Defect Detection (FM 5IGNAL) described in US Pat.
DEMG)4゜o(JLATORWITHDEF'EC
T DETECTION ) J, and Mr. Beca (A
, L. Baker) U.S. Patent No. 4,038,686
Q. Name of invention “Defect Detection and Compensation (January 5FEC)
T L)ETECTION AND C0MPE
N5ATION) J specifications.

The baseband audio signals S and S2 are supplied to the stereo decoder 54 via respective trunk-hold circuits 50,52. Circuits 50 and 52 are of the series and parallel capacitor type as explained below, and when the switch is closed, K is equal to the input signal @, i.e. the output signal aJi+ which tracks (trunks) the input signal.
When the switch is open, the output remains at the last value of the human input signal. 3 functions are generated, defect (cracking sound, buzzing sound) suppression, channel selection, and audio cancellation.
It has two functions. Field effect transistors can be used as switches in each circuit, the preferred switch being a CD4016 containing four chqos transmission gates.
It is a transmission gate like type integrated circuit. High-level human power closes the transmission gate, and low-level input opens the gate.

Circuits 50 and 52 are maintained in a normal tracking mode by high level output signals provided by AND gates 56 and 58. Gate 56 is defective fingernail signal S
3. Audio cancellation signal AM and channel fixed ratio times 8'S
5 and when any one or more of these signals are present (all active at low levels).

The low level @ (!-'
Occur. Gate 58 subsides circuit 52 in the same manner as described above in response to defect signal S4, audio cancellation signal AM and channel immobilization signal S6. The channel immobilization signal S5.56id is provided by the first position of the two-pole three-position channel selection switch 60. Position II I I
At +, the signal S6 is coupled to ground, which cancels the signal IS2 by the force, and at position “2 I+, the signal @S5
is coupled to ground fV, so the signal @ Sl i−
Erase, place % 1131+ (step 1 f 1 position),
The signal on the chair is also grounded. When switch 60 is in stereo position 3, Fj'-+85 and S6
A Flor-Anoff 0 resistor (not shown) may be connected to contacts 1 and 2 to ensure that the voltage is at a high logic level.

Channel 2 flow sensor (CJI-2) is 9o5K
It differs from Channel 170 Losenosa (CH-1) in that it includes a carrier absence detector for automatically canceling the signal S2@7 in the absence of the audio carrier of f(z).

The channel-absence detector includes a low-pass filter 62f! that integrates or smoothes the defective pulse S4. ``Have.

An inverter (not shown) may be used to provide positive defective pulses to the filter 62 so that the output of the filter is proportional to the number of defective pulses or defective pulse rate. When there is no 905KHz carrier, K is
The defective pulse rate becomes even more, and filter 6
A high output voltage detected by the detector 64 is generated at the output of 2, and a carrier wave disappearance signal S'7 (low level when active) is generated.
to occur. This signal S7 is the signal S2 in the demodulator 46.
It is prohibited to erase the Nohdan width device, and also gate 58
is applied to the inhibit gate 66 which inhibits the defective pulse S4 in the defective pulse path to the gate 58, thereby inhibiting random energization of the gate 58 to prevent unwanted noise from being generated in the trunk-hold circuit 52. To prevent. Demodulator 46
An inhibitable amplifier suitable for use in
) U.S. Pat. No. 4,257,009 to K.A.
IRCUITFORA DIFFERENTIAL A
MPLIFIER, ) J.

Signals S1, S2, S5 are fed into a dual mode stereophonic decoder matrix 54. And this stereo decoder life matrix 54 TV converter 2
6. Generate audio output signals S8, S9.810 to be supplied to audio output terminals 70 and '72, respectively.

Terminals 70 and 72 are connected to the right input terminal (L) and the left input terminal (L) of the user's stereo audio device.

The Tecoder e-matrix 54 is 198 mentioned above.
U.S. Patent Application No. 248, filed March 30, 2013
The format shown in specification No. 776 is used.
When a matrixed stereo record, a non-matrix monophonic record, or a bilingual record is played back, the operation is as follows. First, for matrixed stereo signals, the signals Sl, S2 are the stereo sum (L
10B) and the difference (L-R). When switch 60 is in stereo position B, signal S
5 is high, decoder matrix 54 adds 81 and 82 to generate left channel output signal 810, subtracts 82 from Sl to generate right channel output signal S9, and also adds S9 and SIO. In addition, an L+R monaural output signal 88 is generated which is provided to the television modulator 26. For monaural or channel 1 (CH-1) 2 Japanese signals (non-matrix) K, switch 60
88.89.8 of the decoder matrix 54.
Coupled to 1011% output. In order to reproduce channel 2 of a bilingual record, switch 60I'i is placed in position 2 to erase signal Sl, and at the same time the operation of the signal subtraction circuit in decoder matrix 54 is stopped, and signal S2 is Signal output of matrix 54 88°S
9.810. For channel 2 playback, the subtraction circuit in decoder matrix 54 is deactivated to prevent signals S9 and 810 from being in opposite positions, thereby canceling signal S8 and Prevents the creation of out-of-phase audio fields in stereo equipment. Details regarding this are not disclosed in the above-mentioned US patent application specification.

To improve the signal-to-noise ratio (S/N ratio), the stereo signal is compressed during recording and expanded during playback, as described above. This is not necessary for monaural or bilingual signals. The remaining parts of the video disc playback device have three functions: That is, (1) compressed h
(2) Amplify the compressed signal with a constant gain. (3) 11j-enabled signal S9.8 generated when changing the source switch 106 of the playback device (for example, from off to on, or from on to 1 off);
In order to suppress ten low frequency, high amplitude baseband transients, selected i' also cancels the output of the reproduction device during the operating mode.

More specifically, the signals @S9 and SIO are connected to the output terminal 7 of the regenerator by respective variable gain amplifiers 80 and 82.
0 and 72. Gain control signal Sll is commonly supplied to the gain control terminals of amplifiers 80 and 82 through a circuit including a multi-time fixed Guinamink filter 84. Regarding the above-mentioned multi-time constant dynamic text filter, for example, U.S. Patent Application No. 229,743, filed on January 29, 1981 and entitled "SIGNAL EXPANDER," January 1981. ``SIGNAL EXPANDERW with adaptive control circuit'' dated 29th.
ITHAI) APTIVE C0NTR0L CIRC
These patent applications (Japanese Patent Application No. 57-13194, Japanese Unexamined Patent Publication No. Merger application as No. 150237/1983) Detailed information in the Memorandum a
As mentioned above, the smoothing time constant of the filter 84 changes the dynamic variation of the control value B (811), and some b adapts to this variation so that a rapid gain change appears as an audible signal. 2. Variable gain amplifier 8
0.82 is LMI37o exhibiting a gain proportional to the value of the bias current supplied to its gain control terminal.

It may be an integrated circuit such as a type integrated circuit.

When such a current controlled variable gain amplifier is used in a regenerator, the output of filter 84 is suitably conditioned to present a high output impedance.

and 'h can be realized by coupling filter 84 to amplifiers 80 and 82 through a voltage-to-current converter.

The gain control signal 811 is set to 3 depending on the operating state of the playback device.
selectively obtained from two different signal sources.

It consists of a detector 86 that rectifies the first signal 8-#i/f'i signal s9 and SIQ, and the obtained output signal is connected to a resistor R.
A resistor-capacitor (
RC) Supplied to the low-pass communication filter. This filter produces a smooth output voltage that varies as a function of the amplitude of signals S9 and slo. This variable voltage is used to bias amplifiers 8o and 82 for expanding the reproducer output signal. Appropriate values for R and l are 3000 ohms and a value for C1 of H0 and 33 microfarads. Another signal source of the control signal Sll is a power supply voltage source (10V
) and ground, and is a voltage divider consisting of a resistor and R3 coupled between the filter 84V and the transmission gate 88.
It has a jointed exit tongue 70. The value of the resistor is sufficient to allow the voltage taken from the tangent 70, when passed through the filter 84, to bias the amplifiers 8o and 82 and amplify the signals s9 and SIO with a constant (not zero) amplification factor. It is chosen to have a value that is reasonable. A third source of signal 811 is coupled to ground via capacitor c2.
and is coupled to the power of filter 84 via diode D1 and transmission gate 88. Diode D1 may be connected directly to the input of filter 84 as shown by the dotted line. In an embodiment of the invention, the audio cancellation signal AM is normally at a high level and is set to a low level (eg, ground level) when audio cancellation is required. Diode DN-1 has a polarity so as to block the η voice cancellation signal from filter 84 when a record is being played.

When a voice cancellation signal is present, diode I)1 is forward biased, connecting filter 84 to ground;
This causes amplifiers 80 and 84 to operate to attenuate the output signal of the reproduction device.

Any transient signals associated with the output signal are also attenuated.

Capacitor C2 is relatively large (eg, 10 microfarads or more) compared to capacitor C1, and is
It has two functions: smoothing M and delaying turn-off of signal AM. Although further smoothing is provided by filter 84, the rate of change in gain of amplifiers 80 and 82 due to voice cancellation is relatively limited.

This prevents signals due to transient changes from being introduced into the output value of the reproduction device when the signal AM is in a changing state. By slightly delaying the gain by capacitor C2, the transient changes occurring in the outputs of demodulators 44 and 46 are further ensured that the transients occurring at the outputs of demodulators 44 and 46 are sufficient to stabilize when playback resumes and the audio output signal terminates. time (for example, 20
It is named with - so that it has about 0 milliseconds).

Transmission gate 88 has the function of selecting one of the three control signal sources to control variable gain amplifiers 80 and 82. In stereo mode, gate 88 is open and signal 811 is compressed h4
No.6-89 and SIO vary as a function of the amplitude, variably stretching the output signal of the playback device. In mono or dual language mode, gate 88 is closed.

Signal S11 is maintained at a constant level determined by the resistor and comb, and amplifiers 80 and 82 operate as constant gain amplifiers for uncompressed signals S9 and SLOK. 'In all operating modes except playback I+, gate 88 is closed and diode DI is not turned on in response to audio cancellation signal AMff, causing signal 811 to be at ground level.

Amplifiers 80 and 82ij allow the output signals of the regenerator to stand out and attenuate any transient signals generated by demodulator 44 or u46 in response to opening and closing of regenerator power switch 10.

The transmission gate 88c has a collector electrode connected to the control input of the gate 88, and is connected to the power supply voltage +V through a parallel circuit.
It is controlled by a common emitter-connected (NPN) transistor QIK. This parallel circuit includes a collector full-up 0, that is, a load resistor 902 connected in parallel to a series circuit consisting of a stereo display light emitting diode (Ll-; D) 92 and a current limiting resistor 94.
Contains. When transistor Q1 conducts, the LED stereo display lights up and a low voltage is applied to transmission gate 88, thereby turning gate 88 off and outputting signal Sll.
is varied as a function of the signals s9 and 5LCI to variably expand the audio output signal of the playback device.

Transistor Ql is another NPN) inside transistor υ
Normally turn-on pace current is supplied.

The emitter-to-collector path of transistor Q2 is connected to a current limiting resistor 9 between the +V supply and the pace of transistor Ql.
6 and directly connected to 11. Transistor Q2 is
It is normally turned on by a carrier erasure signal 87 (normally high and low when no carrier is present) supplied to the pace through a current limiting resistor 98. transistor. The l pace also has a movable arm connected to contacts l and 2 of the second part of the selector switch 60 which is connected to ground. Resistor 98 and diode D2
It is connected to terminal SQ through. This switching structure satisfies three first-order conditions: (1) the carrier erasure signal S7 exists, (2) the squelchro o exists in the non-stereo position IM (l or 2), and (3) the video squelch signal If any one of the conditions exists when the signal SQ (low level in the NU dynamic state) is present, the transmission gate 88 will close and the stereo display LED 97 will turn off.

To further explain the operation of the playback device, assume that the power switch 10 is closed, the audio channel selection switch 60 is in the stereo position (3) as shown, and a stereo record is being played. do.

Under such conditions, the carrier wave disappearance signal S7°, the video squelch signal SQ, and the audio cancellation signal AM are
1 is also at the red level, the stereo display LED 97 is lit, and the amplifiers 80 and 82 expand the compressed baseband stereo signals S9 and 810 to a certain degree. , if a defect is present in the audio carrier, signals S1 and S2 are erased by placing the defective pulses S3 and 541d, track-and-hold circuits 50 and 52, respectively, in a hold mode of operation, while the reproduction device is in a rest mode of operation. At the time, Shin8'S7, AM and SQH
Both levels are at low levels. Signals S7 and SQ together turn off stereo display LED 92 and close gate 88. At the same time, signal AM (1) holds circuit 50.52;
(2) filter 84;
By grounding the input of the audio signal 'S'12, any transient signal generated by the Oi regulator 44 or Vi46 and passing through the circuit 50 or 52 is eliminated by the conduction of the diode D1. variable gain amplifiers 80 and 82 biased to operate as attenuators when
is ultimately fully controlled by When playing a bilingual record or a monophonic record, switch 60 is in the non-stereo position, the desired channel 1 or 2 is selected with h, gate 88 is closed, and amplifiers 80 and 82 are in the non-stereo position. Its operation is similar to the previous one, except that it operates as a constant gain amplifier for compressed signals. In this mode of operation, the voice cancellation ID station:
Amplifiers 80 and 82 are transient signal suppressors (attenuators).
The mode of operation of the playback device to be biased as, i.e. “
It provides the same functions as ``off'', ``load 11, ``1 pause 1+, 6 scan'', etc.

As previously mentioned, capacitor C2 provides the dual function of smoothing and termination delay of the voice cancellation station. Also, the filter 84
A certain degree of smoothness is also provided by Therefore, the audio cancellation signal does not abruptly change the gain of amplifiers 80 and 82, causing gain changes that may introduce transient signals into the audio output signal of the playback device. can be prevented as much as possible. When the regenerator is in the off state, capacitor C2 is normally in a discharged state. When the power switch is closed, the discharge state of the capacitor C2 causes the diode Dlij to be initially biased to 1; then the amplifiers 80 and 82 are
C is initially in attenuation mode, so when switch 10 is closed [at that time signal AM is also at low level]
, it is possible to suppress the transient signal at turn-on which increases the processing circuit of the reproducing device.

The reason for delaying the end of the audio cancellation signal at turn-on is to provide sufficient time for the audio processing circuit to reach steady operating conditions (this time is the time required for the amplifier to stabilize after the DC power supply voltage is applied). ). Does the relatively large capacitor c2 have the effect of delaying the end of the audio cancellation signal? It is something to give. However, if it is desired that the above-mentioned delay be provided by the microalloy sensor control unit by means of a suitable program, then
There is no need to use capacitors for the above delay purposes.

70 logs for the delay is well known in the microgrossenosa art. The filter 84 receives the AM signal -
Since it has the effect of smoothing the AM signal end delay 2, the capacitor C2 can be omitted from the reproducing device by providing the delay 2 with a controlled microgross processor. If signal S
9 and/or 810, the effect of charging capacitor C1 is canceled by capacitor C2 and the audio cancellation signal AM which is in a low level state.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an embodiment of a video disk reproducing apparatus according to the present invention, with some parts shown in the form of blocks and other parts shown in the form of a schematic circuit diagram. 10... switch,

Claims (1)

[Claims] (1) A single source switch with on and off states for controlling and controlling the supply of operating power to the playback device, and a signal switch for playing the taster record and generating at least one FM audio carrier signal. demodulation means for demodulating the FM audio carrier signal to generate a baseband signal having a direction of 1b1 that exhibits transient disturbances when the state of the ``skewer W switch''changes; and the baseband signal. and an output for generating the output signal of the reproduction device.
a first mode of operation for varying the gain of the amplification means as a function of the amplitude of the baseband audio signal, and a second mode of operation for the gain of the amplification means to be substantially constant and non-zero; and in the third #j operation mode, the gain of the amplifying means is attenuated to a level sufficient to attenuate the output signal of the reproducing device and suppress the transient disturbance. A disc playback device comprising a control means.