JPS6156581B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a reproduction stylus transfer control system, in which the tracking servo polarity is switched multiple times when the reproduction stylus is forcibly transferred in the radial direction of a disk-shaped information recording medium. It is stable and
It is an object of the present invention to provide a transfer control system that can extremely smoothly transfer a regenerated needle to a desired track.

The present applicant has previously proposed, in Japanese Patent Application No. 52-25260 and others, that the main information signal and the first to third tracking control reference signals (hereinafter referred to as "tracking signals") are geometrically controlled without forming a needle guide groove. The main information signal and the first to third tracking signals are statically recorded by a disk-shaped information recording medium having an electrode function recorded as a change in its physical shape, and relative sliding scanning of the disk-shaped information recording medium with a reproducing needle having an electrode. We proposed a playback device that reads and plays back the changes in capacitance. In addition, in the disc-shaped information recording medium proposed by the applicant mentioned above, a video signal, etc. is recorded as the main information signal in four fields per revolution on a spiral main track, and the recording frequency band of the main information signal is The first and second tracking signals _p1 and _p2 , which have lower frequencies and different frequencies, are switched every rotation period of the recording medium, and are arranged in a burst pattern corresponding to the horizontal blanking period. A sub-track is formed in the middle part between the above-mentioned main tracks adjacent to each other, and the switching connection part of _p1 and _p2 (within the vertical blanking period) is recorded.
The third tracking signal _p3 is used to switch the tracking polarity of the tracking servo circuit.
is recorded at a level below a predetermined level so as not to affect the main information signal.

FIG. 1 is a diagram schematically showing the recording arrangement relationship of recording tracking signals on this disk-shaped information recording medium.
In the figure, the ○ mark is _{the p1} (or _p2 ) recording position, and the △ mark is the recording position of p1 (or p2).
_p2 (or _p1 ) indicates the recording position, and the solid line indicates the track center line of the main track. Further, the third tracking signal _p3 is recorded at the position indicated by the broken line in FIG.

FIG. 2 is a block system diagram of an example of a disk reproducing apparatus proposed by the present applicant, and FIG. 3 is a partially enlarged perspective view showing the reproducing state of the disk-shaped information recording medium and reproducing needle shown in FIG. 1. In both figures, reference numeral 1 denotes a disk-shaped information recording medium (hereinafter abbreviated as "disc") having the recording track pattern shown in the first figure, which is placed on the turntable 2 shown in FIG. 2 and are rotated synchronously at high speed. On the surface of the disk 1, as shown in FIG. 3, there is a main information signal recording main track consisting of repeated flat surfaces 26 and pits 27, and a tracking signal _p1 recording sub-track indicated by 28 consisting of repeated pits and flat surfaces 26. A tracking signal _p2 recording sub-track is formed by repeating the pits and the flat surface 26 as shown at 29, and the main information signal in the direction of the arrow is a video signal with a field frequency of 60 Hz such as an NTSC color video signal. (In the case of color video signals such as PAL and SECAM systems,
(rotates at 750rpm).

Further, 4 is a regenerated needle, and an electrode 4a is fixed by vapor deposition on the rear end surface, and the bottom part indicated by 4b is a disk 1.
electrode 4a and disk 1.
The electrostatic capacitance formed between the two detects changes in the intermittent row of pits and converts it into a high-frequency signal. The regeneration needle 4 is moved along the spiral main track in the direction of the rotation axis of the disk 1 by a feed mechanism (not shown).

The high frequency signal (recorded signal) read by the reproducing needle 4 is supplied to a demodulation circuit 6, _{a p3} detector 7, and band filters 8 and 9 via a preamplifier 5 shown in FIG. 2, respectively. The demodulation circuit 6 demodulates the main information signal reproduced from the main track. Also _p3
The detector 7 selects and extracts the third tracking signal _p3 from the reproduced signal, and also extracts the third tracking signal p3 from the reproduced signal.
When the tracking signal _P3 cannot be obtained due to dropout or the like, a signal corresponding to _p3 is output and supplied to the switching pulse generator 11.

The band filter 8 selects the frequency of the first tracking signal _p1 from the reproduced signal and applies it to the first input terminal of the switching circuit 10, and the band filter 9 selects the frequency of the first tracking signal _{p1 from the reproduced signal and applies it to the first input terminal of the switching circuit 10.}
The selected frequency is applied to the second input terminal of the switching circuit 10. The switching circuit 10 uses the band filter 8,
The output terminals of band filters 8 and 9 are connected to the input terminals of detection circuits 13 and 14 separately, and on the other hand, during the low level period, the output terminals of bandpass filters 8 and 9 are switched to be connected to the input terminals of detection circuits 14 and 13. Connected. The level of this switching pulse is changed by the playback tracking signal _p3 every rotation period of the disk 1, and also when a kick pulse is generated from the kick pulse generator 12 (however, during the p3 playback period, the level of the switching pulse is changed by the playback tracking signal _p3 ). (excluding the hard pulse that occurred during the period). This is because in each of the above cases, as can be seen from FIG. 1, the recording tracking signals _p1 and _p2 of the sub-tracks on the inner circumferential side and the sub-tracks on the outer circumferential side with respect to the main track are reversed.

The signals subjected to envelope detection by the detection circuits 13 and 14 are respectively supplied to a differential amplifier 15, which generates a tracking error signal according to the level difference between the two signals. This tracking error signal has a polarity that corresponds to the direction of track deviation and a level that corresponds to the amount of track deviation, and after being converted into desired drive power by the drive circuit 16, the tracking coil 17
is applied, thereby displacing the reproducing needle 4 in a direction and by an amount that corrects the upward radial track deviation of the disk 1.

According to the playback device proposed by the present applicant, which performs the above operations during normal playback, since the needle guide groove is not formed in the disk 1 as described above, it is possible to perform stay motion playback, slow motion playback, and fast motion playback. Various so-called trick plays such as motion playback and high-speed position search can be performed, but during this trick play, the playback needle 4 is forcibly moved to the adjacent main track by one track pitch in order to change tracks. , for example, the fourth
A forced transfer pulse (hereinafter referred to as a "kick pulse") as shown in FIG.

In addition, if the above-mentioned kick pulse is generated at a time other than when reproducing _{the P3} recorded portion, the level of the output switching pulse of the switching pulse generator 11 changes at time _t2 as shown in FIG. 4B, and the switching The tracking polarity is changed by switching the circuit 10.

However, until just before the switching pulse generation time _t1 shown in FIG. 4A, the regeneration needle 4 was sliding on the disk 1 at the stable point shown as A in FIG. When tightening the adjacent track to reach the stable point shown by B in the figure, at time t ₁
During the period up to _t2 (for example, about 150 μs), the switching pulse shown in FIG. 4B is at a low level and has a tracking polarity that pulls the regeneration needle 4 to the stable point shown as A in FIG. 6, so that a large external force is generated. It was necessary to add an additional force to the adjacent truck. Here, in FIG. 6, the horizontal axis indicates the track arrangement cut in the radial direction of the disk 1, _p1 and _p2 indicate the first and second tracking signal recording positions,
Moreover, the main track is shown between them. Furthermore, the vertical axis in FIG. 6 indicates the magnitude of the external force required to turn the regeneration needle 4, the solid line indicates the magnitude of the external force when the switching pulse is at a low level, and the broken line indicates the magnitude of the external force required to turn the regeneration needle 4. The magnitude of the external force when the switching pulse is at a high level is shown. Note that when the external force is 0 or less, the regenerating needle 4 is retracted to a stable point (on the track center line) indicated by a circle by the tracking servo circuit without applying any external force.

Furthermore, in the above case of switching from stable point A to B shown in FIG. 6, since the switching pulse becomes high level after time _t2 as shown in FIG. 4B, the external force applied to the regeneration needle 4 is as shown in FIG. As shown by the broken line, the closer it gets to the stable point B, the smaller it needs to be. Therefore, after the above-mentioned kick, there is a risk that the regeneration needle 4 will go too far past the stable point B due to inertia, so during the period from time t ₂ to t ₃ (for example, about 150 μs), it will move in the track direction of the stable point A. It was necessary to apply a large external force to move the regenerated needle 4 as a so-called braking force. As described above, according to the device previously proposed by the present applicant, it is necessary to apply a large external force to the regeneration needle 4 at the start of the kick and immediately before the end of the kick, and therefore the peak value of the kick pulse shown in FIG. This required a large drive power, and the movement of the regeneration needle 4 was unstable.

The present invention solves the above problems,
One embodiment will be described below with reference to FIGS. 5 and 6. The present invention relates to an improvement of the switching pulse generator 11 shown in FIG. 2. For example, the switching pulse generator 12 generates a switching pulse having a waveform as shown in FIG. It was designed to do so.

Now, when the regeneration needle 4 is at the stable point A shown in FIG. 6 and is under tracking control, the operation of kicking it toward the stable point B shown in the same figure will be explained. At time _t4 , the kick pulse is At the same time as the switching pulse is generated, the switching pulse changes from a low level to a high level as shown in FIG.
The result will be as shown by the broken line in the figure. In other words, the regeneration needle 4 is switched to an unstable tracking state with respect to the track A by switching the above-mentioned switching pulse, and becomes in a state where it can be caused to track either of the adjacent tracks without applying an external force.
Moreover, due to the generation of the above-mentioned hard pulse, the regeneration needle 4
is accelerated in the direction of the track where stability point B is located, and the kick is started.

Next, at time _t5 when the regeneration needle 4 is moved to the vicinity of the center line of the track where the stable point B is located,
In order to apply an external force in the opposite direction to the regeneration needle 4 as a braking force to prevent the regeneration needle 4 from overshooting its track center line due to inertia, a kick pulse of opposite polarity is output from the kick pulse generator 12, and at the same time a switching pulse is generated. The switching pulse from the generator 11 changes to a low level as shown in FIG. 5B. As a result, as the regeneration needle 4 approaches the center line of the track where the stable point B is located, it is necessary to apply a greater external force to the regeneration needle 4 as shown by the solid line in FIG. That is, by switching the tracking polarity, the tracking servo circuit is switched to a state in which the regeneration needle 4 is caused to track the tracks on both sides of the track where the stable point B to be tracked is located,
A force is applied in a direction that prevents the regenerated needle 4 from being transferred by the kick. Therefore, the regeneration needle 4 is moved not only by a force in the opposite direction to the kicking direction due to the reverse polarity of the kick pulse as a braking force, but also by a force in the opposite direction to the kicking direction due to the switching of the tracking polarity. Therefore, compared to the conventional method, the peak value of the kick pulse can be made smaller, and the kick pulse can be made to land on the stable point B on the desired track, and the transfer can be rapidly stopped at time _t6 when the regeneration needle 4 reaches the stable point B. I can do it.

In this way, according to this embodiment, by switching the polarity of the switching pulse three times to coincide with the rising and falling edges of the kick pulse, even with a kick pulse having a small peak value, the reproduction needle can be stably and reliably directed to the desired track. 4 can be changed tracks. However, the present invention is not limited to the above embodiments, and the switching of the switching pulse polarity (tracking polarity) does not necessarily have to coincide with the rising and falling edges of the kick pulse.
The polarity of the switching pulse may be changed in response to a change in the level of the hard pulse.

Furthermore, the generation of the above-mentioned kick pulses and switching pulses can be performed accurately with a simple configuration by using a microcomputer.

As described above, the playback stylus transfer control system according to the present invention picks up and plays a disc-shaped information recording medium in a predetermined signal recording format using the playback stylus, and picks up and reproduces the first and second signals that are discriminated and separated from the playback signal. A tracking control reference signal is supplied, and a switching pulse for switching the tracking polarity of a tracking servo circuit for controlling the tracking of the reproducing needle based on the relative level difference between the two is used to connect the reproducing needle to the disc-shaped information recording medium. The center of the target track is switched in response to the phase of the kick pulse that causes the needle to be forcibly moved in the radial direction of the needle to change the track to the target track. During the period up to the second point in time when the regeneration needle reaches a position slightly away from the line position, the tracking polarity is such that the regeneration needle is tracked on the target track, and from the second time point onwards, the regeneration needle is near the center line of the target track. During the period up to the third point in time, the regeneration needle is set to a tracking polarity in which tracking is controlled by the tracks on both sides of the target track, and then switched to a tracking polarity in which tracking is controlled by the target track. The regeneration needle can be reliably forcibly transferred to the desired track with a peak value smaller than the peak value of the kick pulse in the regeneration device previously proposed by the applicant, and the transfer control of the regeneration needle when changing tracks can be controlled. It has features such as being able to increase stability.

[Brief explanation of the drawing]

FIG. 1 is a diagram schematically showing the recording arrangement relationship of recording tracking signals of a disc-shaped information recording medium, which is a previous proposal by the applicant, and FIG. 2 is a proposal by the applicant to which the present invention can be applied. FIG. 3 is a partially enlarged perspective view showing the reproducing sliding state of the recording medium shown in FIG. 1 and the reproducing needle, and FIGS. 5A and 5B are waveform diagrams showing an example of the kick pulse and switching pulse in the system of the present invention, respectively. FIG. 3 is a diagram schematically showing the relationship between a tracking stable point, tracking polarity (external force applied to a regenerating needle), and a track. 1...Disc-shaped information recording medium (disk), 2...
...Turntable, 4...Reproduction needle, 8, 9...Band filter for tracking signal separation, 10...Switching circuit, 11...Switching pulse generator, 12...Kick pulse generator, 15...Differential amplifier .

Claims (1)

[Claims] 1 Main information signals are sequentially recorded on the main track without forming a needle guide groove, and the sub-tracks approximately in the middle between the center lines of adjacent tracks of the main track are used for first and second tracking control. Reference signals are alternately switched and recorded in each recording unit of the main track, and a third tracking control is performed on the main or sub-track corresponding to the switching recording position of the first and second tracking control reference signals. The disk-shaped information recording medium on which the reference signal for tracking control is recorded is picked up and played back using a playback needle, and the first and second reference signals for tracking control that are discriminated and separated from the playback signal are supplied, and the relative relationship between the two is A switching pulse for switching the tracking polarity of a tracking servo circuit for controlling the tracking of the reproducing needle based on the level difference of the reproducing needle is forcibly moved in the radial direction of the disc-shaped information recording medium. The regeneration needle is switched in response to the phase of the kick pulse that causes the track to change to the target track, and the regeneration needle reaches a position slightly away from the center line position of the target track from the first point near when the track change starts. The period up to point 2 is a tracking polarity in which the regeneration needle is tracking controlled on the target track, and from the second time point to the third time point when the regeneration needle reaches near the center line of the target track. The regenerating needle is characterized in that the regenerating needle is controlled to have a tracking polarity in which tracking is controlled on the tracks on both sides of the target track, and then to a tracking polarity in which tracking is controlled in the target track. Transfer control method.