KR800000137B1 - Implement to detect and correct locked groove in video disc playback apparatus - Google Patents

Abstract

a phase locked loop for filtering an error voltage when a needle passes a "locked groove" comdition in playback of a video disc ; a voltage comparator which the filtered error voltage output is applied to, detecting signals only exceeding a selected threshold level to reduce effect of noise ; and corrected signal generating means comprised a retriggerable one-short, a staircase voltage generator, an one-shot, a drive pulse generator and a drive pulse shaper.

Description

Closed groove detection and correction device for video disc playback device

1 is a schematic diagram illustrating a video disc player device comprising a closed groove detection and correction device in accordance with the principles of the present invention.

2 is a circuit diagram showing a circuit using the closed groove detection and correction device of FIG. 1 according to an embodiment of the present invention.

FIG. 3 shows a circuit suitable for use to validate the function of the detection device element shown in the schematic diagram in FIG. 2. FIG.

4 is a perspective view of a portion of a player device in combination with a closed groove escape mechanism that may be used in the circuits of FIGS. 2 and 3 to complete the device of FIG.

The present invention relates to a novel video disc playback device and method, and more particularly, to an apparatus and method using a new detection and correction principle of a so-called "closed home" playback state involving unnecessary repetition of playback of a particular home circuit. .

John Kay on October 15, 1974. U. S. Patent No. 3, 842, 194 to Clemens describes a video disc playback device of variable capacity type. In this device, the information track consists of geometric changes in the bottom of the spiral groove in the disc, the bottom surface of which consists of a conductive material covered with a thin film of dielectric material.

)는 기록할 때 사용하는 비디오신호의 진폭에 따라 변화하는 주파수변동에 따라 철부(

) 지역으로 바뀐다. 그러므로, 기록된 신호의 형태는 비데오신호에 따라 변조된 반송파 주파수이다.The change in capacitance appearing between the conductive electrode on the tracking needle and the conductive material of the disc is generated as the disc is rotated by the support turntable, and this change in capacitance is sensed even after recovering the recorded information. In a particular form used as the groove floor information track in the invention of Clemens, the recesses that extend across the groove floor (

) Is a convex part in response to a frequency change that varies with the amplitude of the video signal used for recording.

Changes to the region. Therefore, the type of recorded signal is a carrier frequency modulated according to the video signal.

When the above-described type of disc record is played back, it often occurs that a defect appears in the disc groove, which prevents the needle from continuously (inwardly forwarding) tracking the continuous line of the disc groove. In other words, when the needle enters a defect, the needle repeats one or more already crossed lines. In some cases, the outward deflection of the needle is repeated each time it hits the defect portion continuously. This state is referred to herein as the "closed groove" state, in which the same record information is repeated, bringing disturbances (and hence noise) to the display.

EUGENE Oh. U.S. Patent No. 522,820, filed by Kaiser under the title of "Video Disc Record and Recording Playback Apparatus having a Spiral Synchronous Accumulation Position and Its Method," records a helical accumulation of synchronization information in a continuous groove line. An apparatus is described. In one embodiment of the kaiser apparatus, the degree of staggering is a line segment recorded from a radial arrangement with the start of a horizontal synchronizing pulse segment recorded on a given home circuit in which the time of the horizontal synchronizing pulse segment recorded in a given home circuit is It is to be deviated to the jade distance corresponding to about 1/10.

According to the principles of the present invention, the above-described synchronization position staggering can be confirmed in an apparatus for automatically detecting the appearance of a closed home state while playing a video disc of a Kaiser type. The phase instability of the regenerated sync pulses returns the needle to the already traversed groove line. The closed groove detector according to the present invention combines with a device responsive to a reproduced sync signal to distinguish phase instability related to the return movement of the needle from phase instability for other reasons.

According to an embodiment of the present invention, this phase instability determination function is reproduced during disc playback, and the loop device whose phase is closed in response to the horizontal synchronization component of the recorded signal, and the filtered false voltage of the phase closed loop. This is done by a voltage comparator responding to the output. The voltage comparator outputs when an erroneous voltage pulse of a magnitude sufficient to exceed the comparator threshold (of polarity coinciding with the direction of the phase transition along the needle deflection towards the outwardly located groove line) is represented by the closed loop of the phase. Supply the impulse. During normal playback, minor phase errors due to transitional phase instability due to noise pulses and self-time-based jitter do not usually indicate false-voltage pulses that are larger than the comparator threshold. Inward needle deflection (skip forward) represents an incorrect polarity voltage pulse with respect to the comparator response.

There is a possibility that outward needle jumps occur outside the closed grooves. Closed grooved states also speed up self-correction. For example, assuming that a needle hits and externally deflects for the first time, assuming that it normally tracks the groove line, it can be eliminated when hit again. According to another aspect of the present invention, a series of repetitive synchronous phase instability (each with appropriate sensitivity and size) is used to positively indicate the closed groove state.

In an embodiment of the present invention, the iterative instability identification function includes a stepped voltage generator (according to the output impulse of the voltage comparator described above) and a stepped voltage generator for generating an appropriate number of input pulses (for example, 4) within a suitable period. Only when receiving is done by an identification pulse generator having an input threshold that exceeds the output of the stepped voltage generator. In a transitional state that enters disc player motion (which is related to needle position instability due to player vibration and occurs with a needle that is lowered to start the playback cycle), the skipping period of a complex groove is given a needle position. It continues until it stabilizes on the home line. In addition, at the beginning of the playback period, the transition period of the frequency synchronous pull-in to the phase closed loop described above is maintained when a large number of large amplitude error voltage pulses appear. The comparator output pulse repetition rate for the transition state described above is faster than the repetition rate of the synchronous phase instability associated with the closed groove state (the latter speed depends on one instability per tentable rotation when the external needle deflection is in the adjacent line). , Slower speed when the external needle deflection is large). According to another aspect of the present invention, indicative of an incorrectly closed groove in response to the transition state of the above-described type is provided with a closed groove detector to identify a (real or wavy) fast phase unstable phase synchronization. It is prevented by having.

In an embodiment of the invention, this repetition rate identification is taken by a retriggerable one-shot circuit superimposed between the voltage comparator and the stepped voltage generator described above. Round speed, or later, impulses are repeated one-to-one at the output of a retriggerable one short circuit. A series of impulses with repetition rates significantly faster than the circumferential speed are inverted into a single output pulse by a retriggerable one short circuit.

Preferably, identifying the closed groove state initiates a needle movement with characteristics tailored to the closed groove state, thus allowing for normal playback. According to yet another aspect of the present invention, the closed groove exit mechanism operates according to a statically closed groove identification. In an embodiment of the present invention, the release mechanism takes the form of a piezo groove skipper element which deflects the needle inward when actuated by waves of appropriate size, polarity and waveform. Marvin A., filed Aug. 22, 1974, entitled "Disc Record Home Skipper Device". Ridham filed US Patent 499, 55l and filed November 12, 1974. yen. Mr. Crooks, US Pat. No. 522,818, describes various types of home skipper devices suitable for leaving the aforementioned closed grooves. The sawtooth waveform of the appropriate size and polarity can be derived from the output of the aforementioned identification pulse generator in order to operate the home skipper.

The objects and advantages of the present invention will be readily understood by reading the following description set forth by those skilled in the art with reference to the accompanying drawings.

In FIG. 1, part of the video disc record player is shown in a schematic diagram to show a general arrangement of a closed groove detection and correction device according to an embodiment of the present invention. The grooved video disc record 20 having the synchronous signal recording positions arranged in a spiral for each of the types of Kaiser applications described above is provided for the desired playback rotation speed (e.g. at 450 rpm) by means of a suitable rotation drive mechanism 12, on the turntable being rotated. Is reset.

Disc record 20 is a coated form described in the Clemens patent document described above, which constitutes an information track at the bottom of the spiral groove of the record, which consists of geometric variations representing the carrier frequency modulated by the composite video signal as described above. The tip of the needle 40 enters the helix of the disc record 20, and the needle 40 follows the continuous line of the rotating record spiral groove which stably moves toward the inner center of the disc 20 as the record proceeds. In order to easily move the needle 40 radially without changing the position of the needle in the record groove, a suitable radial drive mechanism (not shown) supports the needle 40 in proper synchronization with the rotational drive provided by the drive 12. The pick-up part is moved radially inward. F. March 11, 1975 showing the arrangement of the pick-up parts and the driving mechanism for the above-mentioned related operations of the record and the pick-up parts. egg. Reference may be made to US Pat. No. 3,870,835 to Grant.

In the playback of the Clemens patent described above, the needle 40 engages a conductive electrode that couples with the disk material to form a capacitance change as the needle passes through the geometric change of the groove bottom. As in the Clemens patent, the pickup circuit 50 is electrically coupled to the electrode of the needle 40 and converts the needle-disc capacity change into an electrical signal change representing the recorded signal. The pickup circuit 50 was set on March 18, 1975. second. It may also be in the form shown in US Pat. No. 3,872,240 to Carlson et al. The output of the pickup circuit 50 including the frequency-modulated carrier is applied to the FM demodulator 51 which demodulates the carrier modulated at the demodulator output stage C to represent the composite video signal output.

The synthesized video signal appearing at terminal C is applied to the video signal processing circuit 53 which functions to process the FM demodulator output in a form usable for a conventional television receiver. The synthesized video signal recorded here displays a color screen and mixes chromaticity components in the form of "embedded subcarriers". This processing circuit was Jay on September 16, 1974. G. The form shown in US Patent Application Nos. 506 and 446 filed by Ameri is advantageous. In this form, processing the composite color video signal separates and filters the synthesized signal to separate the respective brightness and embedded subcarrier chromaticity components, and frequency converts the chromaticity components to the band positions available for use in the color television demodulator. Applying the separated brightness components to a suitable video frequency de-emphasis circuit, and recombining the de-emphased separation brightness components and the frequency-converted separation chromaticity components to form an output synthesized color video signal. This output signal appears at the output terminal C 'other than the processing circuit 53 of FIG. At the midpoint (inside and outside the brightness component channel of processing circuit 53, after separation and de-emphasis), another output for application to synchronous separator 55 is derived at processing circuit 53.

The synchronous separator 55 separates the deflection synchronous component from the reproduced synthesized signal and exhibits a pulse output at terminal S corresponding to the horizontal synchronous component of the recorded signal. Closed groove detector 57 monitors the horizontal synchronous component output at terminal S to determine the presence of a "closed groove" playback. If it is identified that there is a closed groove condition that needs to be corrected, detector 57 displays a transducer operating pulse at terminal L to apply to the home skipper transducer 59. In operation, the transducer 59 deflects the needle 40 to a more internal groove line to ensure a closed home playback condition.

The groove skipper converter is a piezoelectric bimorph element as described in the above-mentioned U.S. Patent Nos. 499 and 557, and the support for needle 40 in the manner described in the above-mentioned U.S. Patent No. 522,818. It is combined with a pickup part having a.

2 illustrates a circuit arrangement useful for performing the function of a closed groove detector 57 in a FIG. 1 arrangement according to an embodiment of the present invention.

In the arrangement of FIG. 2, a separate horizontal synchronizing component useful at terminal S is applied to the phase-locked loop circuit 60, which phase-responses to the oscillator output and the synchronizing signal from the voltage controlled oscillator 61, terminal S. And a low pass filter 65 responsive to the output of the detector 63 and the phase detector 63, the filter showing a filtered false voltage for the oscillator 61 to apply according to the frequency control voltage. The filtered misvoltage output of the low pass filter 65 is applied to the input terminal I of the voltage comparison 70.

During normal playback operation (after the transition " sync in " section of the playback period), the output of the oscillator 61 is closed in phase to the reproduced sync signal. That is, oscillator 6l is a given (i.e., quadrature) phase relationship maintained between the actuator and oscillator input for phase detector 63, and is in frequency and phase sync relationship with a separate horizontal sync signal applied to terminal S. Under normal playback conditions, minor deviations from a given phase step (e.g. due to noise in the synchronous comparator output or basic jitter in residence) do not exceed the comparative threshold of the voltage comparator 70. A pulse is generated at terminal I.

However, when the needle jumps to the outwardly directed groove line, a relatively large misvoltage pulse appears at terminal I. During the jump, there may be a loss of the synchronous input at terminal S, but due to the accumulation effect of low pass filter 65, oscillator 61 continues to apply input to phase detector 63 to maintain normal phase. If the needle is grounded to a more outer groove line and the signal is applied to terminal S again, significant deviation occurs from the normal phase relationship between the detector inputs. The continuous period of the output of oscillator 61 (which has the memorized phase again) is derived from repeating home circuits that deviate significantly from the steady state (the amount of departure is determined by the degree of synchronization position staggering used in the record and the size of the outward needle jump) Has a phase relationship to the synchronized signal. For example, it is assumed that the recording information of the horizontal synchronization position staggering for the adjacent line is 1/10 of the above line intervals, and the external deflection for the next adjacent line is the needle jump size. In this assumption, the phase shift is about 36 degrees. Detecting the phase deviation advances the phase of the reproduced synchronization signal (e.g., when synchronous staggering is selected for the purpose described in the Kaiser application above). A known degree of phase departure continues for a period of time (determined by the lowpass characteristic of filter 65) and gradually decreases as the frequency of oscillator 61 adjusts to reduce the deviation.

The final filtered false voltage pulses appearing at terminal I have a relatively large peak amplitude and have a given polarity which represents a well known synchronous pulse phase. The voltage comparator 70 has a polarity according to a given polarity, and the comparative threshold is set at the level exceeded by the pulse peak in the known state. When the input of a given polarity exceeds the comparator threshold of comparator 70, the output pulse is displayed at comparator output 0, which has a fixed amplitude and bandwidth along the range where the input exceeds the threshold. Comparator 70 does not respond to an input that is antipolar to a given polarity. Therefore, if the needle skips forward (for example, jumps to a more internally located adjacent line) and the sync signal is above ground, the comparator 70 does not respond to a pulse of polarity indicating the sync ground. The relatively large amplitude error voltage pulse generated at I prevents the output pulse from being displayed at terminal 0.

In the circuit arrangement of FIG. 2, the retriggerable one-short multivibrator 80 responds to the bypass output pulse represented by comparator 70 at terminal 0. The retriggerable one-short circuit 80 includes an NPN transistor 86 having a collector connected to a constant voltage source by a resistor 87 and an emitter connected to ground. Transistor 86 is normally biased in a conductive state with a resistor 84 and a diode 85 connected in series between the constant voltage source and the base of the transistor 86. Diode 85 is polarized in the same direction as the base-emitter diode of transistor 86 in the biasing current path. Capacitor 83 shunts the series coupling of diode 85 and base-emitter path of transistor 86. Resistor 81 is an anode of diode 82 connected to the junction of resistor 84 and capacitor 83, and is connected between terminal 0 and the cathode of diode 82. Resistor 81 has a resistance value less than that of resistor 87.

Output terminal 0 is at a constant voltage large enough to keep diode 82 normally unconductive. When the comparative threshold is exceeded, the terminal 0 becomes the negative potential and the diode 82 becomes a conductive state. Capacitor 83, charged to constant voltage, is quickly charged to negative voltage through a low-impedance path provided by resistor 81 and conductive diode 82. Charging to the potential across capacitor 83 cuts diode 85 and transistor 86 off. When the comparator output pulse is terminated and terminal 0 is again at constant voltage, diode 82 is again in a non-conductive state. However, transistor 86 does not return to the extremely conductive state. This is because the charging voltage accumulated in the capacitor 83 makes the transistor 86 non-conductive until the capacitor 83 is recharged to the positive voltage through the resistor 84. Therefore, as the comparator output pulse ends, for a given minimum period of time (determined by the time constants of resistor 84 and capacitor 83), transistor 86 remains off.

At the end of a given minimum period, if no continuous comparator output pulses are involved, the potential across capacitor 83 becomes positive, causing the base-emitter path of diode 85 and transistor 86 to be in a forward conduction state. It returns to the state. When a continuous comparator output pulse is involved, the conduction state of transistor 86 is delayed until a pulse-free minimum period is reached. The length of the above described minimum period for the continuous off of transistor 86 is selected to be smaller than the time required for the disc to make one full revolution during record playback (i.e., less than 1/15 second at 450 rpm rotational speed). However, for the purpose as described below, the minimum period selection is selected to be 1/11 second so that it coincides with a part of the rotation period.

The output of the retriggerable one-short circuit 80 is applied to the stepped voltage generator 90. The voltage generator 90 includes a diode 93, a capacitor 91 connected between the diode anode and the collector of the transistor 86 and a capacitor 94 connected between the diode cathode and ground. The capacitance value of the capacitor 91 is smaller than the capacitance value of the capacitor 94.

The generator also includes a diode 92 comprising a grounded anode and a cathode connected to the junction of capacitor 91 and diode 93. A resistor 95 having a large resistance value is shunted to the capacitor 94.

When the initial output pulse of comparator 70 appears at terminal 0 to trigger the one-short circuit 80, the junction of resistor 87 and capacitor 91, which is already clamped to ground potential by conductive transistor 86, is free to rise in voltage. Capacitors 91 and 94 are then charged from the voltage source through a charge passage that includes resistor 87 and the current forward biased diode 93. Since the charge time constant is short compared to the minimum hold-off period for transistor 86, it is fully charged. The charging voltage (voltage across the supply voltage-forward biased diode 93) is distributed across capacitors 91 and 94 in inverse proportion to their respective capacitance values. Assuming the conduction state by the transistor 86, the capacitor 91 is quickly discharged through the passage consisting of the conductive transistor 86 and the diode 92. However, capacitor 94 remains charged at the selected portion of the voltage source, diode 93 is biased non-conductively, resistor 95 exhibits high impedance to discharge current and capacitor 94 discharges very late.

If a continuous output pulse is generated by the comparator 70 soon after the transistor 86 returns to the conductive state, an additional step of charging is applied to the amount of charge retained by the capacitor 94. Therefore, the potential across capacitor 94 is stepped up in step with the comparator output pulses with the appropriate time.

When the potential across capacitor 94 exceeds the threshold level, the monostable multivibrator 100 depends on the voltage needed to establish a conductive state in series coupling of the diode 101 and the base-emitter path of the input transistor 102 of the one-short circuit. Is triggered. This series coupling is shunted across capacitor 94. The resistor 103 is connected between the collector of the NPN input transistor 102 and the electrostatic source. This resistor 103 is shunted by the series coupling of resistor 105 and capacitor 104. The base-emitter path of the output transistor 107 and the diode 106 to one-shot are connected in series between the junction of the resistor 105 and the capacitor 104 and ground. The collector of the NPN output transistor is connected to a constant voltage source through a resistor 108 and to the base of the input transistor 102 via a feedback transistor 109.

Since input transistor 102 is typically nonconductive and diode 106 and output transistor 107 are typically conducting, forward bias to the base-emitter paths of diode 106 and transistor 107 is applied through resistor 105 at the electrostatic source (nonconductive). Connected to the collector of transistor 102). Capacitor 104 having a diode connecting plate made negative with respect to the opposite plate is charged under this condition. When the output of the stepped voltage generator 90 puts the transistor 102 in a conductive state, the voltage drop at the collector turns off the diode 106 and the transistor 107. The positive feedback to the base of transistor 102 through resistor 109 finally increased to the voltage at the collector of transistor 107 causes transistor diode 106 and transistor 107 to be cut off by the voltage across capacitor 104 and transistor 102 is resistor 108 and 109. Through the one-shot, the one-shot is quickly switched to be in a conductive state by the supplied forward bias. This condition continues for a period of time necessary to charge the current flowing through the resistor 105 to reverse the potential across the capacitor 104 and again the forward bias across the base-emitter path of the diode 106 and transistor 107 is brought into a conductive state. Let it appear When the collector of transistor 107 is almost at ground potential, transistor 102 is cut off.

Therefore, the rectifying output pulse is represented by the one-short circuit 100 in the collector of the output transistor 107 having the output pulse width (eg 110 ms) determined by selecting the RC coupling time constant of the capacitor 104 and the resistor 105. The driving pulse generator 110 is applied to the output of the one-short circuit 100.

The drive pulse generator 110 typically includes a nonconductive input transistor 112. The series coupling of the resistor 111 and the base-emitter path of the NPN input transistor 112 is shunted across the collector-emitter conduction of transistor 107. The transistor 112 is normally turned off because the transistor 107 is in a conductive state, but becomes conductive while exhibiting a one-short output pulse when the transistor 107 is cut off. The collector of transistor 112 is connected to a constant voltage source in series through resistors 113 and 114.

The base of the PNP transistor 115 is connected to the junction of the resistors 113 and 114, and the emitter returns to the constant voltage source. The collector of transistor 115 is connected to a negative voltage source by a resistor 115 kV.

The transistor 115 is normally in a non-conductive state, but is turned on in accordance with the conductive state of the transistor 112. The collector of transistor 115 changes from a negative supply voltage to a positive supply voltage. This transition appears across the gate-cathode passage of SCR 116 to trigger SCR 116 into a conductive state.

The cathode of SCR 116 is connected to a negative voltage source, and the anode of SCR 116 is connected by a resistor 119 to an adjustable tap of a potentiometer 119 kV having fixed terminals connected to positive and negative positive voltage sources, respectively. The tap adjusts the amplitude of the output pulses of the generator, denoted by the transformer transformer 118, which has a primary winding 118P in series with the capacitor 117 across the anode-cathode passage of the SCR 116.

The voltage pulses across the primary winding 118P in response to the triggering of the SCR 116 appear to have a polarization voltage at both ends of the secondary winding 118S and the diode 121 connected in series with the capacitor 122 across the secondary winding 118S. Resistor 123 shunts capacitor 122. Resistor 124 couples the junction of diode 121 and capacitor 122 to the input terminal L of the home skipper converter. When the converter is in the form of the above-mentioned piezoelectric bimorph element, it appears as a capacitive load in the drive circuit and is shown in FIG. 2 as a capacitor T coupled between the terminal L and ground.

The saw-wave waveform appears across the capacitor 122 in response to the transformer output pulse as the capacitor 122 charges relatively quickly through the conductive diode l21 and discharges relatively slowly through the shunt resistor 123. The converter operating waveform shown across the capacitor T is the sawtooth waveform described above, but has a longer rise time as determined by the charging impedance represented by the resistor 124. The rise time suitable for the operation of the home skipper in the form of FIG. 4 is 10 ms. The discharge of the converter capacity, T, takes place through resistors 124 and 123 in series.

When the drive pulse is indicated by the generator 110, the voltage at the collector of the PNP transistor 115 converts from the negative potential to the electrostatic potential as described above. According to this voltage conversion, the output of the stepped voltage generator 90 is reset to the base voltage (eg, the ground voltage). The reset circuit input terminal R is directly connected to the collector of transistor 115 and the anode of diode 97. The cathode of diode 97 is connected to the base of the emitter grounded NPN reset transistor 96. The collector-emitter path of the reset transistor 96 is shunted across the cascaded output capacitor 94 of the generator 90. The reset transistor 96 is in a non-conductive state at the negative potential of the terminal R, but attempts to become conductive according to the drive pulse indicated by the generator 110 to discharge the capacitor 94, causing the stepped voltage generator 90 to be a new charge forming cycle.

From the above description, it can be seen that the apparatus of FIG. 2 is not related to the respective output pulse generation by the comparator 70 and the operation of the home skipper converter. There should be a sequence of these output pulses, and if the behavior changes, the time assumed to complete the sequence should not be too long. The triggering of the one-short circuit 100 causes it to occur when the oscillator 90 is pulsed at least four times within a period of approximately three seconds. When the rotational speed is 450 rpm, this threshold setting causes the closed arc condition causing the outward needle deflection of the one or more grooves to operate in accordance with the forward outward needle jump. The necessity of displaying the results before the transducer is in operation is helpful for the positive indication of the closed groove state and prevents the needle from jumping forward if the needle is not jumping back. This necessity is similar to a closed groove but prevents the converter from operating under a transitional state that does not require a modified forward jump form, especially when the rechargeable battery is driven by the retriggerable one-short type device described above. The retriggerable one-short circuit 80 identifies the results of comparator output pulses of repetition rate of 1 or more per disc line by inverting these results into a single output pulse independent of the pulse results of the stepped voltage generator 90. Thus, stale groove closure identification during transition states prevents player instability or needle settling, for example.

Various circuit devices may be used to perform the functions of the phase closed loop 60 and the voltage comparator 70. For example, a commercially available integrated circuit chip is schematically illustrated in FIG. As shown here, the MC 1391P type integrated circuit 62 performs the function of the phase closed loop 60, in response to the separated synchronization signal at the terminal S, and applying a filtered false voltage to the input terminal I of the voltage comparator 70. It is used to The function of the voltage comparator 70 is carried out in the comparator chip 71 of the LM301 AM type, responding to an error voltage at the terminal I, and showing the desired comparator output pulse at the terminal 0.

FIG. 4 shows a part of a pickup part cooperating with the above-mentioned home skipper converter of the piezoelectric bimorph element type. As shown in the top view of FIG. 4, the needle 40 is inserted into the spiral groove of the disc record 20 that is reset along the turntable 10. As shown in FIG. This needle is supported by the support 41 at its end. The support 41 is pivotally supported at its other end by a support 42 fixed to one end of the long pick-up arm 43. The arm 43 is pivotally supported at its opposite end by a second support 44 which is secured to one member of the detachable coupling part 45 (which becomes a magnetic coupling type). The second portion of coupler component 45 (shown in a coupled state) is secured to one end of the piezoelectric bimorph element 59. The other end of element 59 is secured to protrusion 133 of support structure 134. This support structure 134 is known as Al. Seed. Refers to a "cancer extension" transducer of the type described in U.S. Patent No. 3,711,641 to Palmer, which applies a translational motion to arm 43 so that the needle is inserted in the record groove against the error in the needle-groove motion. Let it work vertically The lead wires 131 and 132 are respectively fixed to the external electrodes of the piezoelectric element 59 so that the operating waveform is applied from the driving circuit as shown in FIG.

When operated, the piezoelectric bimorph element 59 bends to pivot the arm 43, causing the needle 41 to move inward radially to stabilize the closed groove. See US Patent Application No. 522,818 to understand this form of home skipper converter device in more detail.

In the FIG. 2 circuit, each series resistor (not shown) is preferably coupled to the gate and reset terminal R of SCR 116 at the collector of transistor 115.

Claims (1)

As the disk 20 rotates, signal pick-ups 40 and 43 for detecting the information display along the spiral information track and a composite video signal output according to the recorded information detected by the signal pick-up are provided. Device 50, 51 coupled to the signal pickup 40, 43 for detecting the information display along a continuous line of the spiral track which normally proceeds toward one end of the spiral track during normal operation. And 53) and a device 55 responsive to the composite video signal output of the output providing device 50, 51 53 for separating the synchronization signal from other components of the composite video signal. A video having a helical information track containing an indication of recorded composite video signal information including a synchronous signal periodically circulated in accordance with a synchronous signal recording position arranged non-radially on a circuit. A video disc playback device for use in a drive, comprising: a controllable oscillator device (61) for controlling the phase of the oscillator in a predetermined phase relationship with the separated synchronous signal; A phase detection device (63) responsive to oscillation of the oscillator (61) and responding to the separated synchronization signal to indicate an erroneous signal indicating departure size and detection in the presence of the synchronized signal; And an output signal display device (70, 80, 90, 100, 110) which includes an comparator (70) responsive to the error signal and provides an output only when the error signal exceeds a predetermined comparison threshold level. Closed groove detection and correction device of bag device.

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