JPS6221430B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a video disc playback device having a tracking servo system, in which a playback element is quickly moved to a recording area where desired video information content is recorded while viewing a playback image. The present invention relates to a high-speed search method for video information content on a video disc, which enables quick cueing of desired video information content.

Video discs that record video information at high density include grooved video discs in which video information signals are recorded in recording traces in guide grooves, and grooved video discs that do not have guide grooves and have recording traces due to video information signals. Two types of video disks are known: a grooveless video disk in which recording is formed on the surface of the disk.

In any of the above-mentioned formats of video discs, video information signals are recorded at high density to ensure a long playing time. It becomes difficult to find a desired video information signal in a short time. Therefore, a means is needed to quickly search for a desired video information signal from the video information signals recorded on the video disc, and various search methods have been tried in the past.

Now, as the search method described above, for example, an address signal is added to the video information signal, the address of the area where the desired video information signal is recorded is specified in advance, and the specified address and video disc are A method in which the reproducing element is rapidly moved to a position where it matches the recorded address signal, or, for example, while viewing the reproduced image while the reproducing element is rapidly moved in the radial direction of the video disk. A typical method is to find the recording area of a desired video information signal within a short time, but the former search method by adding an address requires a complicated and expensive playback device, so the latter method is preferable. This search method is often adopted.

By the way, when implementing a method of quickly searching for desired video information content by quickly moving a playback element to a recording area where desired video information content is recorded while viewing a reproduced image, the video disk In the case of a grooved video disk, the transfer speed of the transfer mechanism that transfers the reproducing element in the radial direction of the disk is several times to several hundred times the normal transfer speed, and the cantilever or damper holding the reproducing element is When the reproducing element is deformed beyond the limit that allows it to be held in the guide groove due to the rapid movement of the transfer mechanism, the reproducing element is removed from the guide groove being traced and the cantilever or damper is removed. The reproduction element, which is held in a holding state close to its natural holding state, begins to trace in a new guide groove. For example, it is common practice to display the video information content of a program as a playback image every few hundred tracks to find the beginning of the program.
When cueing a program using this method,
Since it is not possible to obtain a reproduced image based on video information existing in the middle of a reproduced image due to discrete video information being reproduced, it is difficult to accurately search for a recording area of video information to obtain a desired reproduced image. Alternatively, the movement of the image during reproduction becomes intermittent, resulting in a screen that is difficult to view.

The above-mentioned problems are similar to those of the above-mentioned search method for video information content on a grooved disc, as a high-speed search method for video information content on a grooveless video disc whose playback is performed under tracking control. Needless to say, the same problem occurs when a similar approach is taken, that is, when only the transfer speed by the transfer mechanism is increased as in the normal reproduction mode.

Now, as a high-speed search method for the video information content on a grooveless video disc, in addition to the method described above, there has been a conventional method of applying a track shift pulse signal to the tracking servo system at the vertical blanking period position of the video information. Therefore, attempts have been made to perform high-speed searches for video information content by forcibly displacing the reproducing element to other recording tracks.

In other words, in a playback device for a grooveless video disc, the tracking reference obtained from the grooveless video disc is used so that the playback operation of the video information signal is performed while the playback element always accurately tracks the recording trace. Based on the signal, a tracking control signal generated in a tracking servo system (tracking control system) is supplied to an actuator (drive mechanism) included in the tracking servo system to drive and displace the reproducing element. being done. Then, when a track shift pulse signal is applied to the tracking servo system, the reproducing element is displaced onto a new recording trace, and the reproducing element tracks the new recording trace to generate an information signal. Therefore, it is possible to perform the regeneration operation of
By making the speed at which the reproducing element is transported in the radial direction of the disk by the transport mechanism faster (or slower) than the transport speed during normal image reproduction, and by supplying a track shift pulse signal to the tracking servo system, Trick play such as high-speed image (or slow-motion image) playback at a desired ratio can be realized, and the above-mentioned trick play mode can be extended to move the playback element forward or backward at a faster speed than in normal image playback mode. It is also possible to search for video information content by moving the camera in the same direction.

By the way, if a video information signal including N vertical blanking periods is recorded on a grooveless video disc in the recording trace corresponding to each rotation of the disc, the tracking servo system On the other hand, by supplying a track shift pulse signal during the vertical blanking period of the video information signal, the video information content is searched without causing any disturbance in the image content, and the video information content is Suppose that images are recorded sequentially from the outer circumferential side to the inner circumferential side of the disk, and the direction of movement of the reproducing element in the radial direction of the disk in normal image playback mode is from the outer circumferential side to the inner circumferential side of the disk. If we apply one track shift pulse signal to the tracking servo system for each vertical blanking period so that the reproducing element can be displaced to an adjacent recording trace, then the direction in which the reproducing element is moved by the transport mechanism is When moving from the outer circumferential side to the inner circumferential side of the disk, the transport speed of the reproducing element in the radial direction is (N+1) times that in the normal image reproducing mode, and
When the direction in which the reproducing element is transported by the transport mechanism is from the inner circumferential side to the outer circumferential side of the disk, the transporting speed of the reproducing element in the radial direction is (N-1) times that in the normal image reproducing mode. However, at such a transfer speed, it is impossible to achieve the purpose of searching the video information content on the video disk at a high speed (10 to 200 times the transfer speed in the normal image playback mode) within a short period of time.

Therefore, attempts have been made to speed up the transfer speed of the reproducing element by sequentially applying a plurality of track shift pulse signals during the vertical blanking period. 0.2 to displace the reproducing element onto the adjacent track by applying it to the system.
Since a time of ~0.3 milliseconds is required, if the reproducing element is displaced by multiple recording traces using multiple track shift pulse signals, the reproducing element will accurately move onto the desired recording trace. It may happen that the vertical blanking period ends before you get on the train.
This poses a problem in that the reproduced image has image disturbances above the reproduced image and is difficult to see.

The present invention aims to provide a high-speed search method that can satisfactorily solve the above-mentioned problems in the high-speed search method for video information content on a video disc. The specific contents of the high-speed search method will be explained in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram of an essential part of an embodiment of a high-speed search method for video information content in a video disc according to the present invention. An example of the case where the method is applied to Japanese Patent Application No. 38809/1983) is shown below.

In FIG. 1, reference numeral 1 denotes a grooveless video disk, and this grooveless disk 1 contains main information signals (a color television video signal and an audio signal accompanying it) and a signal f indicating the rotational phase of the disk.
By arranging pits corresponding to _p3 in a spiral shape on a flat surface, spiral recording traces of main information signals are formed on the flat surface at predetermined recording trace intervals (track pitches), and In addition, a spiral tracking reference signal (f _p
1 , f _p2 ) are formed.

Reference numeral 2 denotes a reproducing element that picks up information signals from the disk 1, and this reproducing element 2 is configured to be driven and displaced by a drive mechanism 15 (actuator) in a tracking servo system. The information signal reproduced by the reproduction element 2 is
After being amplified by the preamplifier 3, it is applied to the signal processing circuit 21 and the low-pass filter 4 in the tracking servo system TS.

The signal processing circuit 21 demodulates and processes the color television signal and its accompanying signals as required and sends them to subsequent circuits.

On the other hand, in the tracking servo system TS, the tracking reference signal f is extracted from the reproduced information signal.
_p1 , f _p2 and a signal f _p3 indicating the rotational phase of the disk are extracted by a low-pass filter 4 and passed through band filters 5, 6,
12, the bandpass filter 5 receives a tracking reference signal f _p1 , the bandpass filter 6 receives a tracking reference signal f _p2 , and the bandpass filter 12 receives a signal f _p3 indicating the rotational phase of the disk. Extract them individually and send them to subsequent circuits.

7 is a switching circuit that performs switching so that the tracking reference signals f _p1 and f _p2 extracted by the above-mentioned bandpass filters 5 and 6 are distributed as required to the following two circuits; , 13
1 is a control pulse generator, and this control pulse generator 13 generates necessary switching pulses, kick pulses, etc. for various playback modes and operation modes to control the switching circuit 7 described above, the amplifier 14 described below, etc. give to

The switching pulse generator 13 receives a signal f _p3 indicating the rotational phase of the disk extracted by the bandpass filter 12 described above, and a search signal generation circuit 16 described later.
A signal is given from

Tracking reference signal f _p switched in the required switching manner by the switching circuit 7
₁ , f _p2 are individually detected by the detectors 8 and 9 and then applied to the differential amplifier 10.
From 0, a tracking error signal is output. The tracking error signal is sent to the servo filter 11.
This tracking control signal is amplified by an amplifier 14 and then supplied to a drive mechanism 15, which drives the reproducing element 2 to adjust the width of the recorded trace for tracking control. is driven and displaced in the direction. Further, the kick pulse generated by the control pulse generator 13 is applied to the drive mechanism 15 via the amplifier 14 according to the reproduction mode and the operation mode, so that the reproducing element 2 is controlled by the polarity and magnitude of the kick pulse. It is driven and displaced in the width direction of the recorded trace.

The details of the structure and operation of the tracking servo system described so far are specifically set forth in the specification of Japanese Patent Application No. 1983-38809, which the applicant company previously filed a patent application for. It is recommended that you refer to it.

Now, when searching for video information on a video disc at high speed, the playback element 2 is of course in a state where it is rapidly being transferred in the radial direction of the video disc 1. In particular, in order to be able to know the video information content from the reproduced image,
It is necessary that the reproducing element 2 is rapidly moved in the radial direction of the disk 1 under the control of a tracking servo system.

In the high-speed search method of the present invention, the reproducing element 2, which is under tracking control by the tracking servo system TS, is
A high-speed search pulse signal generated at a random time position by a high-speed search track shift pulse signal generator 16 that includes a variable frequency oscillator whose oscillation frequency is increased or decreased according to the desired search speed for the TS. The playback element 2 is rapidly shifted to one recording track after another by a track shift pulse signal, and the playback element 2 is rapidly moved in the radial direction of the video disk 1 at a desired transfer speed under tracking control by the tracking servo system TS. At the same time, the reproducing element 2 is moved rapidly in the radial direction of the video disk 1, and the reproducing element 2 in the radial direction of the video disk 1 is driven so that the reproducing element 2 rapidly moves in the radial direction of the video disk 1 under tracking control in the high-speed search operation mode. This makes it possible for them to be transferred to other countries.

FIG. 2 shows an example configuration of a track shift pulse signal generator 16 for high-speed searching, which includes a variable frequency oscillator whose oscillation frequency is increased or decreased according to a desired search speed for the tracking servo system TS. In FIG. 2, reference numeral 17 indicates the direction in which the reproducing element 2 is directed from the outer circumferential side to the inner circumferential side of the video disc 1 (hereinafter referred to as the positive direction) in the high-speed search operation mode. , when attempting to transport the reproducing element 2 in the radial direction of the video disc 1 at desired transport speeds in the direction from the inner circumferential side to the outer circumferential side of the video disc 1 (hereinafter referred to as the opposite direction). This is an adjustment knob for setting the transfer direction and the transfer speed of the reproducing element 2. In the illustrated example, the adjustment knob 17 is located at a position where the indicating arrow 17a of the adjustment knob 17 points to scale 0 in the center of the scale plate 17b. When turned clockwise from the adjusted state, the playback element 2 is moved in the opposite direction in the radial direction of the video disc 1 for high-speed searching, and in contrast to the above, the indicator arrow 17a of the adjustment knob 17 moves toward the scale. When the adjustment knob 17 is turned counterclockwise from the adjusted state to the position pointing to 0 on the center scale of the plate 17b, the reproduction element 2
is shown as being transported in the radial direction of the video disc 1 for high speed searching in the forward direction.

The rotation of the adjustment knob 17 described above rotates the slider 18a of the variable resistor 18, but one fixed terminal 18b of the variable resistor 18 is connected to a positive voltage source, and the other A negative voltage source is connected to the fixed terminal 18c of the variable resistor 18, and when the adjustment knob 17 is turned to the position where the indicating arrow 17a points to the scale 0 in the center of the scale plate 17b, the slider of the variable resistor 18 18a is set to zero voltage, and when the adjustment knob 17 is turned clockwise or counterclockwise from the above state, a positive voltage or a negative voltage is applied to the slider 18a of the variable resistor 18. appears.

The magnitude of the above-mentioned positive and negative voltages appearing on the slider 18a of the variable resistor 18 increases as the indicating arrow 17a of the adjustment knob 17 moves away from the scale 0 position at the center of the scale plate 17b.

Therefore, in the case of the illustrated configuration example, when the adjustment knob 17 is moved in the radial direction of the video disc 1 in order to move the reproduction element 2 in the forward direction in the radial direction of the video disk 1 for high-speed searching,
When rotated counterclockwise, a negative voltage appears on the slider 18a of the variable resistor 18, the magnitude of which corresponds to the rotation angle. When the adjustment knob 17 is turned clockwise to cause the movement in the opposite direction, a positive voltage appears at the slider 18a of the variable resistor 18, the magnitude of which corresponds to the rotation angle. Note that the transfer direction of the reproducing element 2 and the slider 18 of the variable resistor 18 in the high-speed search operation mode
Since the relationship with the polarity of the voltage to be generated at a is determined in accordance with the overall configuration of the tracking servo system TS, the relationship between the two is not limited to the above example.

The slider 18a of the variable resistor 18 is connected to the absolute amplifier 19 and the direction detector 23, and the slider 18a of the variable resistor 18 is connected to the absolute amplifier 19.
The voltage appearing at the slider 18a of the variable resistor 18 is amplified and applied to the variable frequency oscillator 20 (for example, the voltage controlled oscillator 20) regardless of its polarity. A polarity discrimination signal corresponding to the polarity is generated and sent to the control pulse generator 13 via the terminal 24.

In the variable frequency oscillator 20, no matter which direction the adjustment knob 17 is turned clockwise or counterclockwise, the frequency increases as the indicating arrow 17a moves away from the center scale 0 position of the scale plate 17b. Alternatively, an oscillation wave with a high repetition frequency is generated and applied to the pulse shaping processing circuit 22.

The pulse shaping processing circuit 22 may be constituted by a waveform shaping circuit that shapes the oscillation wave supplied thereto from the variable frequency oscillator 20 into a high-speed search track shift pulse having a predetermined pulse width, or may be composed of a waveform shaping circuit as described above. , a gate circuit for preventing the output of high-speed search track shift pulses occurring in the vertical blanking period and the time position in the vicinity of the vertical blanking period in the video information signal of the video disc, or as described above. It is composed of a waveform shaping circuit, the above-mentioned gate circuit, and a switch provided so that the above-mentioned gate circuit can be short-circuited as necessary.

The high-speed search track shift pulse output from the pulse shaping processing circuit 22 is applied to the control pulse generator 13 via a terminal 25. As mentioned above, the polarity discrimination signal generated from the high-speed search track shift pulse signal generator 16 and supplied to the control pulse generator 13 from the terminal 24, and the high-speed search signal supplied to the control pulse generator 13 from the terminal 25. What is the track shift pulse for the control pulse generator 1?
3, generation of a switching pulse for switching control of the switching circuit 7 required in the high-speed search operation mode, and a track shift pulse signal for high-speed search having a polarity corresponding to the moving direction of the reproducing element 2. The control pulse generator 13 supplies switching pulses for necessary switching control to the switching circuit 7 during the high-speed search operation mode, and also supplies switching pulses to the amplifier 1.
4, a high-speed search track shift pulse signal having the required polarity is supplied.

Since the output of the amplifier 14 is applied to the drive mechanism 15, the drive mechanism 15 displaces the reproducing element by one recording trace interval (one track pitch) each time a high-speed search track shift pulse is applied to it. Needless to say, whether the displacement is performed toward the outer circumference or toward the inner circumference is determined depending on the polarity of the high-speed search track shift pulse.

When the reproducing element 2 is displaced as described above, a tracking control signal is generated in the tracking servo system TS, and when this signal is supplied to the drive mechanism 15, the drive mechanism 15 pulls the reproducing element 2 back to its original position. However, since the tracking control signal is also applied to the motor drive circuit 26 of the transfer mechanism of the reproducing element 2, the reproducing element 2 receives the high-speed search track shift pulse signal. is transferred by the transfer mechanism in the direction driven and displaced by the drive mechanism 15 when it is supplied.

That is, the tracking control signal generated by the tracking servo system TS is given to the motor drive circuit 26 provided for supplying drive power to the motor M of the transfer mechanism. Since the low-frequency component (DC component) in the tracking control signal extracted by the low-pass filter 26a is amplified by the motor drive amplifier 26b and supplied to the motor M of the transfer mechanism, the reproduction element 2 The transfer mechanism moves the reproducing element 2 in the direction in which the reproducing element 2 is driven and displaced by the drive mechanism 15 in response to the high-speed search track shift pulse signal.
By the movement of the reproducing element 2 by the above-mentioned transport mechanism, the reproducing element 2 is always in a state near the center of the movable range by the drive mechanism, and tracking is performed. The control is most stable and the S/N ratio of the reproduced signal is also good.

As described above, even when the drive mechanism 15 displaces the reproducing element 2 by one recording trace interval for each high-speed search track shift pulse supplied to it, the reproducing element 2 does not control the tracking control system TS. In order to perform a tracking operation on successive recording traces under the following conditions, the switching circuit must be activated every time the reproducing element 2 is displaced by one recording trace interval by successive high-speed search track shift pulses. 7, the two tracking reference signals f _p1 , f
It is necessary that the manner in which _p2 is supplied to the subsequent circuit is reversed.

That is, two types of tracking reference signals are recorded between recording traces of successive main information signals on the disk, and a tracking reference signal f _p1 is recorded on the right side of a certain recording trace.
However, if the tracking reference signal f _p2 is present on the left side, then in the recording trace next to the aforementioned recording trace, the tracking reference signal f _p2 is present on the right side.
When looking at successive adjacent recording traces, the arrangement of the tracking reference signals is reversed one after another, such that the tracking reference signal f _p1 is present on the left, so the reproducing element 2 is displaced by one recording trace interval. This is because, in some cases, the polarity of the tracking control signal must also be reversed for each recording trace.

As can be seen from the above explanation, in the high-speed search method of the present invention, the adjustment knob 1 is adjusted for high-speed search.
The track shift pulse signal for high-speed search generated by the track shift pulse signal generator 16 for high-speed search by turning 7 has a repetition frequency corresponding to the speed of high-speed search. The track shift pulse signal is a noise generated over a period of 0.2 to 0.3 milliseconds each time the playback element 2 performs a track shift operation at an unspecified number of time positions in the video information signal.The noise is generated randomly in the playback screen. The reproduced image above is suitable for use as a reproduced image during high-speed search, considering that there is almost no missing image or distortion of the image, and considering that the image content changes rapidly. It can be used without any problems,
The problems with the conventional example are that the search time is long, that the upper part of the reproduced image is missing or distorted when a plurality of track shift pulses are applied during the vertical blanking period to drive and displace the reproduction element;
According to the method of the present invention, bending and the like can be effectively eliminated.

In the explanation so far, the high-speed search track shift pulse as a track shift signal used during the high-speed search operation is transmitted to the variable frequency oscillator 1.
However, when implementing the high-speed search method, the track shift of the reproducing element 2 with respect to the reproduced image is It goes without saying that it is desirable to perform a track shift operation in a state in which the effect of the operation is even smaller.

Therefore, in order to ensure that the track shift operation of the reproducing element 2 is performed within each vertical blanking period, a kick pulse is sent from the control pulse generator 13 to the drive mechanism 15 via the amplifier 14 during each vertical blanking period. In addition, it is preferable to supply the high-speed search track shift pulse generated by the high-speed search track shift pulse signal generator 16 to the drive mechanism 15 via the control pulse generator 13 and the amplifier 14. .

However, as mentioned above, the reproducing element 2 is always driven and displaced to the adjacent recording trace by the kick pulse during each vertical blanking period;
Track shift pulse signal generator 16 for high-speed search
If the reproducing element 2 is also driven and displaced by a random high-speed search track shift pulse generated in When the random high-speed search track shift pulse generated by the pulse signal generator 16 appears, image disturbance occurs in the upper part of the reproduced image.

In other words, it takes 0.2 to 0.3 for the read element to reach a stable state after performing one track shift operation.
Since it requires milliseconds, if a random high-speed search track shift pulse appears at a time position within 0.4 milliseconds from the time position of the kick pulse within the vertical blanking period, the upper part of the reproduced image is disturbed.

Therefore, in order to prevent the reproduction image from being disturbed due to the above-mentioned causes, the pulse shaping processing circuit 22 in the high-speed search track shift pulse signal generator 16 should be configured with a gate circuit as described above. The high-speed search track shift pulse, which occurs within 0.4 seconds with respect to the time position of the kick pulse during the vertical blanking period, is converted into a high-speed search track shift pulse signal by its gate circuit. It is preferable to prevent the output from the generator 16.

Further, the gate circuit may be configured to be short-circuited by a switch, and the opening/closing operation of the switch may enable or disable the above-described operation in the gate circuit. .

In the case of a video disc with a playing time of 60 minutes on one side, if the high-speed search operation is performed within 1 minute, the track shift pulse signal for high-speed search is used as the track shift pulse used for the high-speed search operation. Either only the pulses generated by the generator 16 are used, or both the pulses generated by the fast search track shift pulse signal generator 16 and the kick pulses within each vertical blanking interval. Although there was no significant difference in the image quality of the reproduced images when compared with the case where a
If the search is performed for a time longer than 1 minute, the pulses generated by the high-speed search track shift pulse signal generator 16 and the pulses within each vertical blanking period are used as the track shift pulses used in the high-speed search operation. It is better to use both Kikku Pulse and Kikku Pulse.
Track shift pulse signal generator 16 for high-speed search
A better reconstructed image was obtained than when using only the pulses generated by .

As is clear from the detailed explanation above, in the high-speed search method for video information content on a video disc of the present invention, tracking is performed under tracking control using high-speed search track shift pulses generated at random time positions. By driving and displacing the operating playback element to one recording trace after another, there is no possibility of large gaps in the video information, and there will be no distortion in the playback image or distortion of the image. In addition, the noise that occurs due to track shifting appears randomly dispersed on the playback screen, so it does not become noticeable and does not affect the video information. Since there are no wide gaps, the movement of the reproduced image is smooth, and the tracking operation is stable during high-speed searching, and the reproduction element is S/
Various advantages can be obtained, such as being able to perform reproduction while N is maintained at a good position, and the method of the present invention satisfactorily eliminates all the problems of the conventional method described above.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a main part of an embodiment of a high-speed search method for video information content in a video disc according to the present invention, and FIG. 2 is a block diagram showing an example configuration of a track shift pulse generation circuit for high-speed search. . 1... Disk, 2... Reproducing element, 3... Preamplifier, 4, 26a... Low pass filter, 5, 6, 12... Bandpass filter, 7... Switching circuit, 8, 9... Detector, 10... Differential Amplifier, 11...servo filter,
13... Control pulse generator, 14... Amplifier, 15...
Drive mechanism, 16... Track shift pulse signal generator for high-speed search, TS... Tracking servo system, 1
7... Adjustment knob, 18... Variable resistor, 19... Absolute value amplifier, 20... Variable frequency oscillator, 22... Pulse shaping processing circuit, 23... Direction detector, 26... Motor drive circuit, 26b... Motor drive amplifier.

Claims (1)

[Scope of Claims] 1. In a video disc playback device having a tracking servo system, a playback element is quickly moved to a recording area where desired video information content is recorded while viewing a playback image, and the desired video is reproduced. When searching for information content at high speed, a track shift pulse signal generator for high-speed searching is provided for a tracking servo system, which includes a variable frequency oscillator whose oscillation frequency is increased or decreased according to the desired search speed. A tracking system made of a tracking hobo system provides a high-speed search track shift pulse signal generated at random time positions by a tracking device, and also controls the transfer speed of the playback element by a transfer mechanism for moving it in the radial direction of the video disk. A high-speed search method for video information content on a video disk that changes according to the DC component of a control signal. 2. In a video disc playback device having a tracking servo system, the playback element is quickly moved to the recording area where the desired video information content is recorded while viewing the playback image, thereby searching for the desired video information content at high speed. In this case, a track shift pulse signal is applied to the tracking servo system at the vertical blanking period position in the video information recorded on the video disk, and a track shift pulse signal is added to the tracking servo system in addition to the track shift pulse signal recorded on the video disk. A track shift pulse signal generator for high-speed searching is constructed including a variable frequency oscillator whose oscillation frequency is increased or decreased according to a desired search speed for a tracking servo system even during a video signal period of video information. A high-speed search track shift pulse signal generated at a random time position by the device is provided, and the transport speed of the reproducing element by the transport mechanism for transporting the reproducing element in the radial direction of the video disk is controlled by the aforementioned track shift pulse signal. A high-speed search method for the video information content on a video disc that changes according to the direct current component of the tracking control signal generated by the king servo system.