JPS58118041A - Information recording and reproducing device - Google Patents

Abstract

PURPOSE:To ensure the faithful following of a track when a disk of high density is rotated at a high speed for an information recording/reproducing device, by detecting the tracking signals which are recorded at both sides of a track with the prescribed intervals by means of a reproducing means and then performing the tracking. CONSTITUTION:Tracking signals 3011, 3012... are recorded on a track 101 in addition to video signals 2011, 2012.... The tracking signal contains two parts like 3001 and 3002, and these parts are shifted by 1/2 track width from the center of the track. If a light beam is placed at the center position of the track, the output is equal to each other between the parts 3001 and 3002. While either one of these outputs is larger than the other when the light beam is deflected to either side. Thus a tracking error signal is obtained in response to the volume and direction of the light beam. Therefore it is required just to control the direction of the optical beam by means of the error signal and so that the error signal is set at 0.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an information recording/reproducing apparatus and an information recording/reproducing apparatus that tracks and detects predetermined information.

In recent years, there has been a growing need to record large amounts of image information, and research on how to do so has been active. Among these, methods of recording information with high density on a rotating body such as a disk are attracting attention. At this time, each frame of information, such as a video signal for television display, is recorded on one track, and a large number of these tracks are arranged concentrically. At this time, in order to record a large amount of information, extremely high-density recording is performed. For example, there is a 1 micron pitch within the track, and a 1 to 2 micron pitch between the tracks. Such high-density disks are fast,
For example, when rotating at a high speed of 60 rotations per second,
The problem is how to faithfully follow this track (tracking).

The present invention is an invention for this tracking.

This will be explained below using the drawings.

Figures 1 to 1 specifically take up a disk and schematically show the tracks.

That is, on a disk 1 of which diameter is about 30 cm, there are tracks 10. ．． 10□, etc. are recorded, and this disk is rotating in the direction of arrow 200.

FIG. 2 is an explanatory diagram of recording signals on a track. In figure A, the reflectance of the surface is as shown in 100□~1003:
Alternatively, it indicates the use of media with different transmittances. This can be done by coating or vapor depositing a suitable material and then recording the transmittance or reflectance depending on the signal. The simplest example is a photographic emulsion.

FIG. 2B shows an example in which signals are recorded by surface irregularities.

FIG. 3 is a basic explanatory diagram of reading signals from such a disk.

The light from the laser 2 is focused on the disc H via a mirror 3, a half mirror 4, and a focusing lens 5, and the reflected light from there is detected via a half mirror 4 and a photodetector 6, and then sent to a demodulator. 8, a signal, for example, a video signal for TV display is obtained. At this time, the signal for tracking is passed through a suitable tracking error signal discrimination circuit 9 to a mirror deflection drive circuit 11 to change the angle of the mirror 3 so that the light is correctly irradiated onto the track. .

FIG. 4 is an enlarged view of the recorded portion of the signal on the track. Track 10. ．． 10°, 1 on 103
00. ．． 100°, 100. It is recorded in the form of roughness, for example, on the surface of the throat.

The track spacing t is approximately 1 to 2 microns, and the signal recording portion d within the track is 1 to 2 microns.

Now, the problem with such a system is how to generate a tracking error signal.

Example 1 A basic example of the present invention is shown in FIG. track 10
1 has the video signal portion 20□I, 2oI□...
In addition to the tracking signals 3011%3012...
... is recorded. This tracking signal is 3
00,. It consists of two parts, 300 □, and these are offset from the center of the track by half the track width.

Now, record this tracking signal in an appropriate format,
When the light beam is located at the center position of this track, the two dragging signal portions 300, . The output from 300□ will be the same, but the more the light beam is deflected to either side, the more one can be made to be larger than the other.

This is shown schematically in FIG.

(a) and (b) are tracking signal portions 30, respectively.
The output is from 01.300□.

In the latter case, since the light beam is located at the center of the track, both outputs are equal, so the difference signal is zero as shown in (C).

Now, when the light beam deviates upward in FIG. 5, the signal in (a) becomes stronger than the signal in (1)), as shown in FIG. (13), and therefore, this difference becomes positive. On the other hand, if the light beam deviates downward, the difference will be much smaller than the signal of the 6th signal (shown in FIG. C1, where the signal in (a) is the peak), and this difference will be negative.

Therefore, the direction of deviation can be known from the differential signal between and. This pattern is shown in FIG. That is, a tracking error signal can be obtained depending on the amount and direction of deviation of the light beam. Therefore, using this error signal, the direction of the light beam may be controlled so that this error signal becomes zero.

The problem here is that the tracking signals 300, . 3
The question is how to record 00□. Generally, FM modulation is performed to obtain a high signal-to-noise ratio. Therefore, the previous tracking signal may be recorded at two different frequencies f, , f2. FIG. 8 schematically shows this, and it can be seen that the tracking signal is expressed in forms with different pitches. The signal will be explained in more detail.

FIG. 9 shows an example of a frequency spectrum when a TVi video signal is FM modulated. For example, the fundamental frequency is distributed between 3.5 MHz and 4.5 MHz (part B). The harmonics are distributed below that (part A). Frequency Hf for two tracking 2 kings,
, f2 are set to 4.5 MHz or higher as shown in the figure, for example. Signal detection at this time is performed as shown in FIG. This description is only for the photodetector 6 and below in FIG. 3.

That is, after the output of the photodetector 6 is appropriately amplified,
It is passed through three bandpass filters.

The filter 121 passes only the video signal components of 4.5 MHz or less through 111, and is further supplied to the demodulator 8 to obtain a video signal for TV display.

On the other hand, the angles of 12° and 123 allow only the f and f2 components to pass through, respectively. These filter outputs are
, 83, the differential amplifier 13, and a suitable error signal generation circuit 9 to send the error signal to the mirror deflection drive circuit 11.

Embodiment 2 FIG. 11 shows a case where the values of f, , f2 are selected in the video frequency domain. A synchronous signal is required to separate the signal from the video signal. FIG. 12 shows the pattern. Video signal portion 20. , ,20. □ During the synchronization signal part 40. ,．． 40. , , will be provided. After this, tracking signals 30□1, 30□2, etc. are provided. The f, , f2 components after this synchronization signal are referred to as a tracking signal.

Specifically, this is carried out according to the circuit shown in FIG.

One of the outputs from the photodetector 6 is sent directly to the video signal demodulator 8□, just as in the present case.

However, the synchronization signal detected from this output is the gate circuit 15. ．． Sent to 15□. This gate circuit operates the filters 12□, 1 only for a certain time immediately after the synchronization signal is detected.
23 is useless. Filter 12□,
123 are f, respectively.

Only the f2 component is allowed to pass through. The subsequent output processing is exactly the same as in the first embodiment.

In the case of a general TV display, the synchronization signal mentioned here is included in the horizontal retrace period, and the tracking signal: p
o o, , 300□, etc. can also be incorporated into this horizontal line period.

Therefore, in the case of general 'Pv display, there is not only no need to newly provide a synchronization signal, but also information loss due to input of a dragging signal, or inevitable increase in bandwidth. It has very practical advantages.

Embodiment 3 In the example of FIG. 5.12, the tracking signals of fI + f2 are arranged adjacent to each other on the same track.

This can actually be simplified further. FIG. 14 is an example of this, in which f, , f2 are arranged temporally shifted. It is therefore easier to record such force signals.

If the track spacing is close, each track always has f,,f
Figure 15 shows a solution to this problem, which makes it difficult to use the 2 signal alone. For example 3001
゜ is track 10. and 10□.

At this time, in the track 10, when the light beam shifts in the -F direction, the f component becomes a dog, whereas in the track 10□, the f2 component becomes a dog. Therefore, in order to correct this difference, it is necessary to invert the sign of the error signal for each track.

In the example of Figure 14.15, the tracking signal is first
Not only does it have the advantage of only needing to write 08, then 300□ sequentially, but it also has the advantage of writing in the margin (such as the bottom of 300□).
It is also possible to record other information.

Embodiment 4 FIG. 16 further simplifies signal recording.
300□1 is used for both tracks 100.10□. In this case as well, the sign of the error signal is easily switched for each track, as in the third embodiment. To record the tracking signal shown in FIG. 16, the synchronization signal 401□
Next to 3001°, then 201□... and 傅<, then in the next track, write 40.2 then 300°, 12th then 20°2.

Embodiment 5 In the example below, in the same track, f
The relationship between l and the 2nd place was @.For example, the 16th place
In the example shown in the figure, tracks 10□ and 10□ have f, respectively.
, f2 is on the upper side.

Therefore, the same tiger as shown in FIG.

The difference signals obtained from the above will continue to have almost the same sign. This is not necessarily optimal for subsequent signal processing. Unfortunately, on the i15.16 side, it was necessary to reverse the sign of the relationship between the error signal and the deviation for each track.

As a method for solving this problem, there is a method shown in FIG.

That is, one track has frir,, f2゜f ・
・F... tracking signal and f2. fll
2 f,, f, tracking signals are mixed.

When the output of the photodetector 6 shown in FIG. 3 is given, the tracking is completely performed as shown in FIG. 18A. That is, (al, (bl are fl, f2, respectively)
(C) is the difference output. If the light beam shifts upward in Figure 17, then 7.1813
The result will be as shown in the figure. As a result, a differential output (C) is obtained.

On the other hand, if it is shifted downward, the result will be as shown in Figure 'j418c.

There is a relationship between the direction and difference signal (c) from the comparison of Figures 18B and C.

That is, considering the fundamental frequency component of the pulse train (C), the 188th. In diagram C, the phase is reversed.

In Figure 18A, the difference signal is zero.

Therefore, if we take the case of Figure 18B as the in-phase component, the 18th
Diagram C is in reverse phase. Therefore, if we find these components in the difference signal and find X = in-phase component - anti-phase component, the relationship between X and deviation is shown in Figure 19, which is exactly the same as Figure 7. and X can be used as an error signal.

In fact, this persimmon detection can be performed using the system shown in FIG. This is an explanation for the case shown in FIG. The same applies to the case shown in FIG. Of the output from the photodetector 6, the tracking signal is sent to the filter 12□
, 123, and a suitable demodulator 8°, 83 [7 and further differential amplifier 1]. The output is supplied to the differential amplifier 13□ via synchronous, anti-phase demodulation circuits 808, 8 (12).This output is supplied to the error signal generation circuit 9.

The following is the same as before.

Finally, recording of tracking signals will be specifically explained.

In this case, video signals are sequentially recorded on predetermined tracks on the rotating disk, and when a tracking signal is to be written, the recording light beam is slightly deflected.
A light beam is made to come to a position offset from the center of the track. For example, in FIG. 16, after writing the synchronization signal section 40,1, the tracking section 300. , and then return the light beam to its original position and continue to 201□. Of these, 300. .

To write a tracking signal in a wide throat area,
It is also effective to drill the light beam in a direction perpendicular to the track.

From the above, it has been shown that the non-inventive method provides simple and positive tracking.

Although the description has been made regarding disks, the same applies to drums, tapes, etc.

Furthermore, although the video signal for TV display has been described as a signal, it is generally effective for recording information.

Also, although the explanation was made using FM modulation as a recording method,
It is clear that it is not limited to this.

[Brief explanation of the drawings] Figure 1 is a conventional explanatory diagram of the disc and track;
3 is an explanatory diagram of the recording format of signals on a disc, FIG. 3 is an explanatory diagram of reproduction of signals from the disc, FIG. 4 is an explanatory diagram of an enlarged view of a track, and FIG. 5 is an explanatory diagram of the signal recording format of the present invention. An explanatory diagram of recording, FIG. 6 is an explanatory diagram of the tracking signal of the present invention, FIG. 7 is an explanatory diagram of the error signal and deviation of the present invention, FIG. 8 is a tracking signal, and FIG. 9 is an explanatory diagram of the video signal and tracking. FIG. 10 is an explanatory diagram of each signal processing system. Figures 11, 12 and 13 are explanatory diagrams of other embodiments of the present invention. FIGS. 14 to 17 are diagrams showing other examples of tracking signals, and FIGS. 18 to 20 are explanatory diagrams of tracking signal processing. Here 1 Dimas 10□~103 Track 1.00. , ~100. Signal recording element 200
Disk rotation direction 2 Laser 3 Mirror 4 Half mirror 5 Lens 6 Photodetector 8 Demodulator 9 Error signal generation circuit 10, ~ 103 Track 11 Mirror deflection drive circuit 12□, 12
2,123 Filter 13.13 13° Differential amplifier I 20 . 20 Information recording part 11] 2 30□,,30.・2 Tracking signal recording section 4
011+401° Synchronization signal recording section 80, . 80□
Synchronous detectors 1001-1003 Signal recording elements 300, . 300 □ Tracking signal agent Patent attorney Susuki 1) Tori Koki 4 Old o 6 Rusho 6 Sonokyu 7 Old Tsutomu Nao et al.
887:) Skull 72 Figure No. 73 No. 14 Figure Rare 15 Hakoman! 9 Old X

Claims (1)

[Scope of Claims] 1. In a recording and reproducing apparatus comprising an information recording medium in which predetermined information is recorded in the form of tracks by unevenness or differences in reflectance, and a reproducing means for reproducing the predetermined information from the tracks. . An information recording and reproducing apparatus, characterized in that said reproducing means detects tracking signals recorded at predetermined intervals on both sides of said track, and tracks said track. 2. The device according to claim 1, wherein the information is a television signal, and the region is provided within a horizontal blanking period of the television signal. 3. Apparatus 0 according to claim 1, characterized in that the tracking signals are recorded as tracking signals of different frequencies.