JPS5826086B2 - Information recording disc and its reproduction method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an information recording disk and its reproduction method, and the present invention relates to an information recording disk and its reproduction method, and by periodically shifting the recording signal position in a direction substantially perpendicular to the track scanning direction, information can be recorded using only one light beam. An object of the present invention is to provide an information recording disc and its reproduction method that can stably and reliably reproduce video signals recorded on the disc.

In the information recording disk in which information is read using a conventional light beam as shown in FIG. If you enlarge the portion of the spiral (or concentric) track pattern shown by black in A of the same figure, it becomes as shown in B of the same figure.

In this track pattern, pits 2 are formed intermittently, and the length of the pits 2 in the track scanning direction changes depending on the video signal before F'M shown in FIG. (The length in the direction perpendicular to the track scanning direction) is approximately constant and the center of the width is recorded so as to coincide with the center line in the track scanning direction.

Note that in the video signal shown in C of the same figure, Sl and S2 indicate color burst signals.

When reproducing this information recording disk, conventionally, as shown in FIG.
Two auxiliary light beams 4a are arranged at positions preceding and following the main light beam 3, respectively irradiating the left edge.
4b and compares the reproduction output values of the auxiliary light beams 4a and 4b to perform tracking control so that the main light beam 3 always scans on the track scanning center line.
The information was being played back.

However, in the conventional method of reproducing an information recording disc using the three light beams mentioned above, the band of the information signal to be recorded is extremely wide, and the groove pitch and the recording time are increased. Since the tracks are formed with a track width of several μm or less, it is extremely difficult to adjust the relative positions of the three light beams, and since three light beams are used, the equipment becomes complicated and expensive. Furthermore, there were other drawbacks such as unstable operation.

In addition, some conventional information recording discs recorded tracking signals, but because the tracking signals were prepared separately and recorded, the tracking signals were recorded on the recording side. It has drawbacks such as the need for a generating circuit and a complicated configuration.

The present invention eliminates the above-mentioned drawbacks, and each embodiment thereof will be described with reference to FIG. 3 and subsequent figures.

3A and 3B are a partial enlarged plan view of one embodiment of the track pattern of the information recording disk according to the present invention, a waveform diagram of an example of a video signal to be recorded, and FIG. 4 is an information recording according to the present invention. 1 shows a block system diagram of one embodiment for recording a record; FIG.

The information recording disc according to the present invention has pits 2 formed on the disc by FMing the video signal to be recorded as shown in FIG. As shown by 6 and 6' in FIG. It is recorded shifted in the opposite direction.

Next, one embodiment of the recording system of the information recording disc according to the present invention will be described with reference to FIG. 4. Radiation emitted from the radiation source 7, for example, a laser beam, is supplied to the optical modulator 8.

On the other hand, an information signal to be recorded, for example, an information signal including at least a video signal, which comes in from the input terminal 9, is supplied to a recording signal processing circuit 10, where it is converted into a signal form suitable for recording (for example, the video signal is converted into an FM signal). , and represents a video signal that has been sliced and subjected to FM repetition frequency after being multiplexed with other low-frequency information signals, and a halo that has been converted into a rectangular wave representing a low-frequency information signal by changing the duty cycle. The signal is applied to the modulator 8 as a modulation signal.

As a result, a modulated laser beam modulated according to the above modulation signal is output from the optical modulator 8, and this beam is transmitted to an acousto-optic deflector (hereinafter referred to as A, 0. deflector).
11.

At the same time, the information signal from the input terminal 9 is supplied to the horizontal synchronization signal separation circuit 12, where the horizontal synchronization signal is extracted and sent to the waveform shaping circuit 13 by connecting two monostable multivibrators in cascade. applied.

For example, one horizontal scanning period (1H) is generated by this waveform shaping circuit 13.
), a pulse whose polarity is positive for the first half of one horizontal synchronization period and negative for the remaining period is output, and after being F'Med by the frequency modulator 14, the pulses are The beam is supplied to a deflector 11, and the angle at which the modulated laser beam is diffracted is alternately changed to the opposite direction by a predetermined angle for each IH.

A, the modulated laser beam taken out from the O0 deflector 11 passes through an aperture 15 that takes out only the first-order diffracted light, an objective lens 16, and then a photosensitive agent coated on a disc-shaped recording master 17 rotating at a predetermined speed. The light is focused and condensed onto 18.

As a result, the track pattern formed on the cutting master disc or the pressed disc surface is such that pits are recorded in a spiral or concentric pattern as shown in FIG. Only the signal recording positions corresponding to the period and the remaining half period are shifted in the opposite direction in the track width direction.

Here, it is well known that when a video signal is recorded, for example, one frame at a time, for each -circular period, the recording position of the horizontal synchronizing signal is always aligned with respect to the direction of the center of the disk.

In the above embodiment, the track pattern divides each horizontal synchronization period into two periods, and the respective signal recording positions are shifted in opposite directions with respect to the track width direction. Instead, further subdivide into 3
It is also possible to divide the period into the above periods and shift the signal recording position for each division.

However, in view of the recording density, it is desirable that the horizontal synchronization signal recording positions be shifted in the same direction in the direction perpendicular to the track scanning direction (in the disk radial direction).

In addition, the above A, 0. Instead of the deflector 11, a device using a substance whose refractive index changes depending on an electric field (potassium phosphate crystal, barium titanate, etc.) or a mirror using deformation due to a piezo effect may be used.

Next, the reproduction method of the information recording disc according to the present invention will be explained.

FIG. 5 shows a block system diagram of an embodiment of the information recording disk reproducing method according to the present invention.

The reflected light or transmitted light whose intensity changes depending on the presence or absence of pits obtained by scanning the information recording disc according to the present invention with a single light beam is incident on the detector 19, where it is converted into an electrical signal. converted.

The output signal of the detector 19 is amplified by a preamplifier 20 and then supplied to an information signal processing circuit 21 and a band amplifier 22 having predetermined band r-wave characteristics.

The information signal recorded in the information signal processing circuit 21 is reproduced and guided to the output terminal 23.

Further, only the carrier frequency Fsync during the horizontal synchronization period is separated by the band amplifier 22, amplified, and supplied to gate circuits 24 and 25, respectively.

By the way, in the present invention, information is read using a single light beam, but at this time, due to a tracking error, the beam spot 35 is located at the track scanning center line (the center of the video signal recording track width that does not include a synchronizing signal) as shown in FIG. 6A. line) 36, scan the horizontal synchronization signal recording pits of τ1 to τ21 to τ2 of the horizontal synchronization signals recorded with a shift in advance, and scan the horizontal synchronization signal recording pits of τ2 to τ32 to τ3. The signal recording pits are hardly scanned.

Therefore, the output reproduction signal level of the detector 19 or preamplifier 20 in this case is as shown in FIG.
It is the largest at τ2, the smallest during the period τ2 to τ3, and the time τ
The video signal recording pit playback level before time τ1 and after time τ3 is an intermediate level between these levels.

On the contrary, when the beam spot 35 is shifted to the right with respect to the track scanning center line 36 as shown in FIG. The τ1 to τ21 to τ2 horizontal synchronization signal recording pits are hardly scanned.

Therefore, the output reproduction signal level of the detector 19 or preamplifier 20 in this case is as shown in FIG. 7B during the period τ1 to r2.
It is the smallest in the period τ2 to τ3, and the largest in the period τ2 to τ3.

However, as shown in FIG. 6C, during normal scanning when the beam spot 35 is scanning on the track scanning center line 36, the horizontal synchronizing signal is recorded in advance with a deviation from the track scanning center line, so it is not reproduced. As shown in FIG. 7C, the signal in the video period is at the highest level, and the carrier frequency levels in the τ, ~τ2 period and the τ2~τ32~τ3 normal synchronization period are all lower than the reproduced signal level in the video period. .

In this manner, the level of the reproduced signal from the horizontal synchronization signal recording position, that is, the level of the carrier during the horizontal synchronization period, increases or decreases rapidly when a tracking error occurs, depending on the direction and displacement position.

Therefore, in this embodiment, this level change is detected and tracking control is performed so that the carrier level change in the horizontal synchronization period between the upper and the adjacent tracks in the track scanning direction becomes as shown in FIG. 7C.

That is, the output signal of the information signal processing circuit 21 is supplied to the horizontal synchronization signal separation circuit 26, where the horizontal synchronization signal is separated into P waves, and then applied to the monostable multivibrator 27 to trigger it.

The output rectangular wave of the monostable multivibrator 27 is further applied to the monostable multivibrator 28 to trigger it, and is also applied to the gate circuit 24 as a gate pulse to keep the gate circuit 24 open for the period τ1 to τ2. be done.

Further, the output rectangular wave of the monostable multivibrator 28 is sent to the gate circuit 25 for the period τ2 to τ3.
It is applied as a gate pulse with 5 being "open".

As a result, at least 1 to τ2 from the gate circuit 24.
The gate circuit 25 takes out the output for a period of at least τ2 to τ3.

Gate circuit 24.250 output signal is envelope detection circuit 29
, 30, where it is subjected to envelope detection, and then supplied to each input terminal of a differential amplifier 33 via low-pass filters 31, 32, where its levels are compared.

This differential amplifier 33 causes the beam spot 35 to be tracked when the reproduced carrier level in the period τ1 to τ2 is higher than the reproduced carrier level in the period τ2 to τ3 (in the case of FIGS. 6A and 7A). Displaced in the scanning center line 36 direction,
In addition, when it is small (in the case of FIGS. 6B and 7B), an output signal with a polarity and level that should displace the beam spot 35 in the direction of the track scanning center line 36 is extracted and applied to the tracking mirror 34. .

As a result, the beam spot 35 is tracked so as to always scan on the track scanning center line 36 as shown in FIG. 6C, and information signals are reproduced more stably and reliably than on an information recording disk.

This embodiment has the feature that information signals can be reproduced without using special signals such as pilot signals.

In addition, in the information recording disc according to the present invention, the horizontal synchronizing signal recording position is shifted from the track scanning center line for tracking control and so as not to affect the playback screen, but the horizontal retrace line is not limited to this. Any portion within the erasing period may be shifted, or even the entire horizontal line erasing period may be shifted.

Furthermore, an information recording disk in which the above-mentioned information signal is recorded as geometrical shape changes on a disk-shaped recording medium has been described.
Of course, the present invention can also be applied to the case where the information signal is magnetically recorded on a magnetic sheet or the like and then magnetically reproduced.

As described above, the information recording disc and its reproduction method according to the present invention divides a part or all of each horizontal blanking period of a frequency-modulated video signal into a plurality of periods, and divides the divided plurality of periods into a plurality of periods during a track. A single light beam scans the track of an information recording disc, which is formed by shifting each signal recording position of the period in a direction substantially perpendicular to the track scanning direction, and the reproduced signal obtained thereby is a track portion shifted in the upper middle band. The reproduction signal levels of the two are compared and used as a tracking control signal, and the video signal is reproduced by the single light beam, which is activated by the tracking control signal. It is not necessary to record a dedicated signal, and therefore the recording system can be configured easily since there is no tracking signal generation circuit. Video signals can be reproduced using only the beams, which simplifies the circuit configuration compared to conventional methods, and eliminates the extremely difficult task of adjusting the relative positions of the three light beams. Since the direction is set to be the same for adjacent tracks, and the position of the shift is made constant in a direction substantially perpendicular to the track scanning direction, it is possible to eliminate the decrease in recording density. Since the adjacent divided signal recording corresponding positions are sequentially shifted in opposite directions in the substantially perpendicular direction, the signals reproduced from the track portions shifted in opposite directions in the substantially perpendicular direction to the track scanning direction. By comparing the levels, the optical beam can be tracked and controlled without using special signals such as pilot signals, and therefore the video signal band to be recorded and played back can be widened, and there is no occurrence of beat interference with the pilot signal. Furthermore, since the position to be shifted is part or all within the horizontal blanking period, it has many advantages such as not having any adverse effect on the playback screen.

[Brief explanation of the drawing]

Figures 1A, B and C are plan views of conventional information recording disks, respectively;
A partially enlarged plan view of a recording track pattern and a waveform diagram of a video signal to be recorded; FIG. 2 is a diagram showing the relationship between a track pattern and a light beam spot in an example of a conventional information recording disk reproduction system; FIG. 3A , B are a partial enlarged plan view of the recording track pattern of the information recording disc according to the present invention, a waveform diagram of a video signal to be recorded, and FIG. 4 is an embodiment for producing the information recording disc according to the present invention. 5 is a block diagram of an embodiment of the reproducing method of the present invention, FIGS. 6A to 6C are diagrams showing respective tracking states of the light beam spot in the reproducing method of the present invention, and FIG. 7A -C are diagrams showing envelopes of reproduced signals in the tracking states shown in FIGS. 6A to 6C, respectively. 7... Radiation source, 8... Light modulator, 9
......Video signal input terminal to be recorded, 10.
...- Recording signal processing circuit, 11... Acousto-optic effect deflector, 12゜26... Horizontal synchronization signal separation circuit, 13... Waveform shaping circuit, 14・・・・・・
...Frequency modulator, 19...Detector, 21...
... Information signal processing circuit, 22 ... Bandwidth amplifier, 24.25 ... Gate circuit, 27, 28.
...Monostable multivibrator, 29,30...
... Envelope detection circuit, 33 ... Differential amplifier, 34 ... Tracking mirror.

Claims (1)

[Scope of Claims] 1. In an information recording disk having a track in which at least a frequency-modulated video signal is recorded and formed as a change in geometric shape, one of each horizontal blanking period of the frequency-modulated video signal is dividing the part or all into a plurality of periods, and forming positions in the track corresponding to signal recording in the plurality of divided periods shifted in a direction substantially perpendicular to the track scanning direction,
An information recording disc characterized in that it is configured to reproduce the video signal using a single light beam. 2. Claim 1, characterized in that the shifted track positions are uniformly aligned in the substantially perpendicular direction, and each position between adjacent tracks is formed in the same direction.
Information recorder listed in section. 3. In the track, the signal recording corresponding positions of the plurality of divided periods adjacent to each other in the track scanning direction are sequentially shifted in opposite directions in the substantially perpendicular direction. An information recording disc as described in either Scope 1 or 2. 4. In a method of reproducing the information signal using a light beam from an information recording disk having a track in which the frequency-modulated video signal is recorded as a change in geometric shape, the frequency-modulated video signal is A track formed by dividing part or all of each horizontal blanking period into a plurality of periods, and shifting the signal recording positions of the divided periods in the track in a direction substantially perpendicular to the track scanning direction. A single light beam scans an information recording disk having a 1000 kHz beam, selects and extracts the carrier frequency of the horizontal synchronization period in the reproduced signal obtained by this, and reproduces the shifted track portion with the extracted carrier frequency component. The levels of the two types of signals obtained by gate outputting each shifted track portion for each period are compared to obtain a tracking control signal, and the one light beam that causes a tracking control operation by the tracking control signal generates an information signal. A reproduction method for an information recording disc, characterized in that the information recording disc is reproduced.