JPS6387616A - Information recording medium - Google Patents

Abstract

PURPOSE:To surely detect off-tracking by staggering the pits recorded along the tracks on a disk surface intermittently and only for a certain period and preventing the overlap of said periods on the staggering periods of the adjacent tracks. CONSTITUTION:The periods when the tracks are staggered slightly to detect an off-tracking signal are discontinuously provided as shown in; for example, the figure, in order to prevent the effective appearance of the influence of the adjacent tracks in the case of tracing a piece of the track. The pits are so recorded that the staggered periods of the tracks do not overlap between the adjacent tracks. Synchronous detection is executed only in the periods where the tracks are staggered and the off-tracking is detected in the case of making reproduction. The envelope detected in the staggered track periods is thereby made to detect the correct off-tracking without receiving the influence of the adjacent tracks.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an information recording medium that records information signals as changes in density and phase on the surface of a rotating disk.

[Conventional technology]

Conventionally, a tracking method (Japanese Unexamined Patent Publication No. 103515/1983) has been proposed for tracking information tracks in this type of device. However, this method uses the envelope of the information signal to detect track deviation signals, so when the track spacing becomes narrow to accommodate high-density information, information signals from adjacent tracks may be mixed in. Therefore, there is a drawback that it becomes impossible to accurately detect a track deviation signal.

[Problem that the invention seeks to solve]

The above drawbacks will be explained in more detail.

First, the principle of the conventionally used information groove (referred to as track) tracking method will be described. FIG. 5 shows the envelope of the information signal detected when the information detection means (for example, a light beam spot or a capacitive head) crosses the track in the radial direction. If the center of the track is O, and the amount by which the information detecting means deviates from the track is represented by δ, then the intensity ■ of the envelope signal changes as shown by a curve 50 with respect to the deviation δ.

When the track 53 is shifted by ±Δ from the center O (the tracks at this time are indicated by 54 and 55), the envelope signals are defined as curves 51 and 52, respectively, as shown in FIG. 5. Considering the positive region of δ, the curve of 51 is 5
The curve 51 is above the curve 2, the two overlap at the 0 point, and the curve 51 is below the curve 52 in the negative region.

If the track is made to meander with an amplitude of Δ and a period of T, and the change in the envelope signal when the information detection means traverses the track in the radial direction is observed, a signal that changes with a period of T is generated. The phase is reversed in the 10 region and the 1 region of δ. Therefore, by periodically detecting this signal, it becomes possible to detect the direction of deviation of the information detection means with respect to the track based on the phase, and detect the amount of deviation based on the amplitude.

The above is the principle of conventional tracking, but in this method, as shown in FIG.
', 62' are lined up and the distance between them becomes close, a portion 63.6 where the envelope signals (represented by curves 60.61 and 62, respectively) at the time of crossing the racks 1 to 62 overlap each other.
4 occurs. In this region, the influence of adjacent tracks interferes with each other, so that even if synchronous detection is performed, accurate track deviation signals cannot be detected.

The present invention can accurately detect a deviation of 1 to 1 rack even when the track spacing becomes narrow in order to record information at high density, and signals from adjacent tracks are mixed into the information signal. It provides an information recording medium.

[Means for solving problems]

In the present invention, in order to effectively prevent the influence of adjacent tracks when tracking one track, for example, as shown in FIG. The meandering periods of the track are provided discontinuously, and the meandering periods of the track are recorded so as not to overlap between adjacent tracks. When reproducing, synchronous detection is performed only during the meandering period of the track to detect deviations from 1 to Rack.

[Effect]

With the configuration shown in FIG. 4, the envelope detected during the track meandering period is not influenced by adjacent tracks, and it is possible to accurately detect track deviation. That is, the geometrical arrangement of the tracks, which is a key part of the present invention, causes the tracks to meander slightly, and the period of the slight meandering varies discontinuously in the rotational direction, but in the radial direction.
The meandering periods of adjacent tracks do not overlap.

〔Example〕

Hereinafter, the present invention will be explained in detail according to examples.

First, the recording apparatus will be explained with reference to FIG. Light (indicated by diagonal lines in FIG. 1) emitted from a recording light source laser 1 (for example, an Ar+ laser) is reflected by a mirror 2, enters an optical modulator 3 (for example, an electro-optic crystal), and is output by a signal 8, which will be described later. Intensity modulated. The output light is incident on a light deflector 4 (for example, an ultrasonic light deflector) by a mirror 2', is deflected by a signal 12 described later, and is formed into a minute spot on the disk 10 by an objective lens 11 via a mirror 2#. form. The disk 10 rotates at a constant rotation speed (for example, 1800 rpm) in the direction of the arrow around the rotating shaft 9. Also on the disk 10 is a recording medium (for example, a metal film or a photosensitive material such as a photoresist).

By irradiating this recording medium with the minute spot mentioned above, the signal 8 becomes 0N due to thermal action or photosensitive action.
A hole (pit) corresponding to -OFF is formed.

Next, regarding the generation of signals 6, 7.8 in Fig. 1, the second
This will be explained using figures. Here, one rotation (1800ppm
), let's take as an example the case where one TV screen is recorded. A video signal from an information source 20 (for example, a VTR, a television camera) is input to an FM modulation circuit 24, where it undergoes FM modulation and becomes a recorded signal 8. In addition, the video signal is transmitted to the sync separation circuit 2.
1 to separate the synchronization pulses (horizontal synchronization pulse, vertical synchronization pulse, color subcarrier). Using the horizontal synchronization pulse and the vertical synchronization pulse, a frame pulse FP representing a frame (corresponding to one screen) is generated, and a clock CKI whose phase matches the color subcarrier and frequency (3, 58 MHz) is generated. CK1 is input to the frequency dividing circuit 22, where it is divided into an appropriate number and given the frequency fx (for example, 500
kHz) signal 6 is generated. This signal 6 is also input to the frequency dividing circuit 23 as a clock CK2, and is frequency-divided to generate a signal 7' having a frequency fz (for example, 50 KHz).

Hereinafter, the function of the above-mentioned signals will be explained according to the time chart shown in FIG. Frame pulse FP is input to flip 25. Then, a frame pulse is generated every time the disk rotates once (frame changes), and the output of the flip-flop 25 alternately repeats 0'' and ''1''.The output of the flip-flop 25 is sent to the exclusive OR circuit 26. input to one side, and output signal 7 from the frequency divider circuit 23 to the other side.
’. Then, as shown in Figure 3, the Nth rotation (N
The output signal 7 of the exclusive OR circuit 26 for the next (N+1th frame) rotation is reversed in phase. This phase inversion is repeated every rotation. If this output signal 7 is used as the gate signal of the gate circuit 5 shown in FIG. 1, and the output signal 6 of the frequency divider circuit 22 is input to the inputs of the circuits 1 to 5, the output signal 12 will be as shown in FIG. The phase in which the signal of frequency f is applied alternately at the N-th rotation and the N+1 rotation 11 is shifted.

When a minute spot on the disk 10 is slightly deflected in the radial direction by the optical deflector 4 in accordance with the signal 12, an information groove as shown in FIG. 4 is formed on the disk 10. This is a hole that represents information (represented by pit nine lines).

With this recording method, meandering periods of the track exist discontinuously in the rotational direction on the disk surface.
Furthermore, in the radial direction, information grooves are formed in which the meandering periods of the tracks do not overlap between adjacent tracks.

Next, the specific configuration of the playback device will be explained using FIG. 7. Light 72 emitted from a light source 71 passes through a semi-transparent mirror 73, is reflected by a movable mirror 74, and is then reflected by an objective lens 7.
5 narrows down to a minute spot. Light reflected from a recorded disk 76 rotating at a constant speed in the direction of the arrow is reflected by a semi-transparent mirror 73 via a movable mirror 74 and enters a photodetector 77. Since the reflected light from the disk undergoes intensity changes depending on the information recorded on the disk, it undergoes photoelectric conversion by the photodetector 77 and becomes an information signal.

After this is amplified by an amplifier 78, it is demodulated by a demodulator 79 and displayed on a television monitor 80. A synchronization pulse is separated from the video signal input to the synchronization separation circuit 81 in the same manner as during recording, a clock CKI is detected, and a frequency f1 signal is obtained by the frequency division circuit 82.

On the other hand, the output from the amplifier 78 passes through an envelope detection circuit 83 to detect the envelope, and the signal is input to a band amplifier (center frequency f□) 84 where the frequency f included in the envelope is
Extract only component 1.

The signal obtained from the frequency dividing circuit 82 and the signal obtained from the band amplifier 84 are input to the multiplier 85, and are multiplied in order to perform synchronous detection. This output is the servo system compensation circuit 8
6 to a drive circuit 87 that drives the movable mirror, and this output moves the movable mirror 74 so that the optical spoilers 1 to accurately track the track.

Although the recording/reproducing embodiments of the present invention have been described above, the present invention is not limited thereto, and the waveform of the minute meandering may be a sine wave, a triangular wave, or any other periodic waveform.

In the above explanation, the case where the tracks are made to meander has been described, but the present invention is not limited to this, but it is also possible to track the tracks by shifting the position of a predetermined synchronization signal between adjacent tracks. . That is, when recording information, it is normal to divide the information into certain sections and record them in chronological order. A synchronization signal can be inserted at a certain period. The present invention performs tracking by shifting these synchronization signals from the synchronization signals of adjacent tracks by a certain fixed position in the track scanning direction. This will be explained below using examples.

FIG. 3 is an enlarged view of a track pattern recorded according to the present invention. Information tracks a, b, c, and d are divided and recorded into a certain section T, and include a main information section j (for example, indicated by ia in track a) and a synchronization signal S (for example, indicated by Sa in track a). ) form one category. When recording a video signal in the so-called NTSC direction, the synchronizing signal S has different characteristics from the main information part i even in the case of other information when it reaches a certain frequency, and can be easily extracted electrically. Further, the synchronization signal S is recorded in adjacent tracks so as to be shifted by a certain amount in the track scanning direction. The value of this t is zero and T
A value other than /2 is possible in principle, but T/3 is most preferable when considering rotational irregularities of the reproducing circuit and recording device. Therefore, if the number of rotations of the disk is N (7 seconds of rotation), the relationship with the information classification period T is N = 1 / (n T -
t) may be determined to satisfy. However, n is a positive integer. FIG. 9 is a block diagram of one embodiment of the reproducing apparatus of the present invention. The output of the signal detector 101 is processed by a signal processing circuit 102 and an information signal is taken out from a terminal 103.

- From the output of the force signal processing circuit 102 to the synchronization signal detection circuit 1
At step 04, only the synchronizing signal S is taken out. Assuming that the track b shown in FIG. 8 is being scanned and the center cb of the track is being traced, the synchronization signal sb can be obtained as shown in FIG. 10(A). Let us consider a case where Cba, which is closer to track a, is traced from the center of track b. At this time, the synchronizing signal Sa of track a slightly leaks into the output of the synchronizing signal detector 104, as shown in FIG. 10-11=(A'). From this output, comparator 105 selects 1~
Figure 10 shows the period T synchronized with the synchronizing signal using a monostable multivibrator 106 which extracts only the periodic signal sb of rack b and generates a pulse with period T/2 at the falling edge of sb.
A pulse is generated as shown in B) to operate the synchronous detector 107.

Therefore, by inputting the output of the synchronous signal detector 104 to the synchronous detector 107, the waveform is detected as shown in FIG. 10(B) and as shown in FIG. 10(C). Similarly, C from 1 to rack C from the center of track b.
Considering the case where bd is traced, the synchronous detector 107
From there, a signal whose polarity is opposite to that when tracing near track a is detected as shown in FIG. 10 (C'). In this way, as is clear from FIGS. 10(C) and 10(C'), the polarity of the signal indicates the direction of track deviation.

Furthermore, if the deviation is large, the leakage of synchronization signals (Sa, Sb) from adjacent tracks also becomes large. Since a signal corresponding to the amount and direction of track deviation can be extracted in this way, tracking can be easily performed by providing this signal to the tracking control circuit 103.

Since the present invention performs tracking by mixing adjacent tracks, it has the feature that even if the recording density becomes high and the number of cross tracks increases, it is possible to l-race the center of the adjacent tracks. The explanation above is based on synchronization signals, but this is not limited to this.If the information to be recorded has a signal that has a constant period and can be electrically separated, tracking can be achieved by similarly positioning this signal differently between adjacent tracks in the track direction. It can be performed.

〔Effect of the invention〕

As described above, the present invention provides accurate and inexpensive tracking of information recorded by forming tracks using optical, electrostatic, or magnetic methods. Furthermore, since there is no need to perform any processing on the information to be recorded or to add an extra tracking signal, it is possible to reproduce the information signal without damaging it.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of an embodiment of a recording device for realizing the present invention, FIG. 2 is a generation circuit diagram of a control signal of the recording device, FIG. 3 is a diagram showing a time chart thereof, and FIG. FIG. 4 is a diagram for explaining the information groove according to the present invention, FIGS. 5 and 6 are diagrams for explaining the principle of tracking, FIG. 7 is a diagram showing the configuration of an embodiment of the playback device, and FIG. 9 is a diagram showing an example of another track pattern according to the present invention, FIG. 9 is a block diagram for implementing the present invention, and FIG. 10 is a waveform diagram for explaining the operation of FIG. 9. No. Z No. 2 @ No. 3 ≠ No. I No. 1 7th cause of trouble

Claims (1)

[Claims] 1. An information recording medium characterized in that pits recorded along a track on a disk surface are intermittently meandered for a certain period of time and are provided so as not to overlap with the meandering period of an adjacent track.