JPH0352148B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a recording method for a disk-shaped recording medium, and more particularly to a recording method for a disk-shaped information recording medium in which information signals including a synchronization signal are recorded as concentric or spiral recording tracks.

FM information signals including synchronization signals such as video signals
A video disc is a disk-shaped recording medium processed by (frequency modulation). The information recording method on the video disk (hereinafter simply referred to as a disk) includes a CAV (Constant Angular Velocity) method and a CLV (Constant Linear Velocity) method. As shown in FIG. 1, on a disc recorded using the CAV method, recording tracks T ₁ ,
Since all the recorded parts of the synchronization signal (indicated by black dots) on the T _o are arranged on approximately the same radius line, there is little so-called crosstalk phenomenon where the synchronization signal of the adjacent track has a negative effect on the reproduced information. There are advantages. On the other hand, since the linear velocity of the outer track is greater than that of the inner track, if the length of one horizontal synchronization period _l1 on the inner track is set appropriately, the section length _l2 on the outer track will be longer than necessary.
This will require the following. As a result, the recording density cannot be increased too much, which is inconvenient for long-term information recording.

On the other hand, on a disc recorded using the CLV method, each track T ₁ ,
Since T _o-1 , T _o , and the length of one horizontal synchronization period l ₁ above are all equal, the recording density is high, making it suitable for long-time information recording. However, since the horizontal synchronization signal recording portions (also indicated by black dots) are not recorded in alignment on the same radius line, so-called crosstalk phenomenon in which reproduced information is adversely affected by information on adjacent tracks becomes noticeable. In other words, if the FM signal corresponding to the horizontal synchronization signal leaks as crosstalk in the section where the FM signal corresponding to the video signal is recorded, the playback information obtained by detecting this leaks depending on the difference between the two frequencies. This is because the beat components mixed in with the video will appear on the screen of the video playback device.

As described above, disks based on the CLV method are suitable for recording information over long periods of time, but they have the drawback of unavoidable negative effects on the screen due to crosstalk.

The present invention has been made in view of the above-mentioned shortcomings of the prior art, and its purpose is to provide a disc-shaped disc that reduces the adverse effects of crosstalk during playback on reproduced images and enables long-term information recording. The objective is to provide a recording method for recording media.

The recording method of the disk-shaped recording medium according to the present invention records information so that the linear velocity is constant while changing the rotational angular velocity in a portion of the recording area of the recording medium where the radius of curvature of the information recording track is relatively small. It is characterized in that the rotational angular velocity is recorded as constant in a portion where the radius is relatively large.

FIG. 3 is a schematic block diagram of an embodiment of the present invention, and is an example of application to an optical recording system.
In the figure, a spindle motor 12 is rotationally controlled by the servo output of a spindle servo circuit 11, and an information recording disk 13 is controlled accordingly.
seems to be rotating. Information recording disk 1
A photosensitive material such as a photoresist is coated on the surface of the photoresist 3, and the photosensitive material is made to be sensitive to light emitted from the laser light source 14.

Here, the light emitted from the laser light source 14 is inputted from an input terminal 16 by an E/O conversion (electrical/optical conversion) device 15, and is inputted to the FM modulation circuit 1.
After the laser beam is converted into a passing/non-passing state according to the information signal modulated by the laser beam 7, the laser beam is irradiated onto the surface of the information recording disk 13 via a fixed mirror 18 and a condensing lens 19. The rotational state of the information recording disk 13 is detected by a rotation detection circuit 20 using a rotary encoder or the like.
A control signal for the spindle motor 12 is obtained by comparing the frequency and phase of the output of this detection circuit and a variable frequency dividing circuit 21, which will be described later, in a spindle servo circuit.

On the other hand, a carriage servo circuit 22 is provided, and the servo output controls the carriage motor 2.
3 is controlled to control the movement of the relative position in the radial direction between the recording laser beam, which is the information recording means, and the information recording disk. The above relative position is
It is detected by a position detection circuit 24 using a linear encoder or the like, fed back to the servo circuit 22, and also supplied to a linear velocity detection circuit 26 and a control circuit 27, which will be described later. The output of the rotation detection circuit is further input to the servo circuit 22, and the rotation of the carriage motor 23 is controlled so that an information track is formed at the correct pitch according to the rotation of the recording disk.

Here, in the spindle servo circuit 11, a signal outputted from an oscillation circuit 25 consisting of a crystal oscillator or the like is frequency-divided at a predetermined ratio by a variable frequency dividing circuit 21 consisting of a variable counter, etc., and a rotation detection circuit A control signal for the spindle motor 12 is obtained by comparing the frequency and phase with the output of the spindle motor 21. Furthermore, the frequency division ratio n in the frequency dividing circuit 21 is
The outputs of the position detection circuit 24 and the rotation detection circuit 20 are used to sequentially change the output of the control circuit 27 according to the linear velocity detection information calculated by the linear velocity detection circuit 26. There is.

That is, the recording linear velocity υ is determined by the angular velocity ω of the recording disk detected by the rotation detector 20 and the distance r from the rotation center of the recording disk 13 to the information recording point P detected by the position detection circuit 24. , in the linear velocity detection circuit 26, the relationship υ=rω is calculated, and the division ratio n is changed stepwise so that the linear velocity υ falls within a predetermined range.
Incidentally, since the position where the frequency division ratio is changed is limited to a predetermined position on the disk as described later, the output of the position detection circuit 24 is input to the control circuit.

The operation of the blocks in FIG. 3 will be explained below with reference to FIG. FIG. 4a shows the change in track linear velocity υ when information is recorded from the inner circumference of the recording disk 13 toward the outer circumference. Section A
In this method, the frequency division ratio in the frequency dividing circuit 21 is gradually changed to reduce the rotational angular velocity ω of the spindle motor 12 from the inner circumference to the outer circumference as shown in Fig. b, thereby keeping the track linear velocity υ constant. . That is, in section A where the radius of curvature r of the recording track is relatively small, recording is performed using the CLV method.

When the position detection circuit 24 detects that the radius of curvature r of the recording track has reached a predetermined value r _o as the carriage motor 23 rotates, a control signal is sent to the control circuit 27 . When the information recording position exceeds the position corresponding to this radius of curvature r _o , the control circuit 27
The output of the variable frequency divider circuit 21 supplied to the spindle servo circuit 11 is made to have a constant frequency, and the rotation speed of the spindle motor 12 is kept constant.
Shift to CAV operation. During this CAV operation period (section B), it is necessary to align the synchronization signal recording portions of adjacent tracks on substantially the same radius line to eliminate crosstalk. The radial position is limited to a predetermined location. Therefore, this switching operation is controlled according to the output of the position detection circuit 24. That is, in order to position the synchronization signal recording portions between adjacent tracks on substantially the same radius line, which is the object of the present invention, the circumference length relative to the radius r when moving to CAV operation must be one horizontal synchronization period or more preferably one vertical synchronization period. It is necessary to satisfy the relationship of an integral multiple of the length S corresponding to the synchronization period, and therefore, switching is required at a radius r _o that satisfies the following relationship.

r _o =mS/2π...(1) m is an integer value.

Here, assuming that the synchronization signals between the innermost track and its adjacent track are recorded on the same radius line, the length S is given by the following equation.

S=2πr ₀・_1/2 ...( ₂ ) Here, r ₀ is the innermost track radius, ₁ is the disk rotation frequency at that time (for example, 30Hz), and ₂
is the horizontal sync signal frequency (15.75kHz) or vertical sync signal frequency (60Hz). Therefore, from equations (1) and (2), the radius r _o when switching to CAV is r _o = mr ₀ · ₁ / ₂ (3). The _control circuit 2
7, or calculate it by calculation, and at the position corresponding to this r _o , from CLV.
Make sure that the operation is switched to the CAV method.

According to the recording method according to the present invention, in the inner circumferential portion
Since recording is performed using the CLV method and the other outer peripheral portion is recorded using the CAV method, if the CAV method, which visually has relatively less crosstalk phenomenon, is recorded for a longer time, it is possible to record only the conventional CLV method. In comparison, the adverse effects of crosstalk are significantly reduced. Furthermore, it is possible to record for a longer period of time compared to recording using only the CAV method.

In addition, the crosstalk phenomenon is dependent on the angle formed between the optical axis of the spot light for information reading and the recording surface, and the warpage of the surface of the recording disk becomes larger toward the outer periphery, and the crosstalk caused by the angle increases. is significantly larger at the outer circumference than at the inner circumference. Therefore, for example, if recording is performed using the CLV method on the outer periphery, the above-mentioned crosstalk phenomenon due to the angle is added to the crosstalk phenomenon inherent in the CLV method itself, resulting in significant deterioration in image quality. Therefore, as in the present application, on the outer periphery
If the CAV method is used and the CLV method is used on the inner circumference, the crosstalk phenomenon can be further reduced.

Note that the track pitch of the CLV recording band at the inner circumference can be made larger than that of the CAV recording band at the outer circumference to reduce crosstalk due to the track pitch.

It goes without saying that the present invention is applicable not only to optical recording media but also to other electrostatic recording media.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a part of a recording disk according to the CAV system, FIG. 2 is a diagram showing a part of a recording disc according to the CLV system, FIG. 3 is a block diagram of an embodiment of the present invention, and FIG. 4 is a diagram showing a part of a recording disk according to the CLV system. FIG. 4 is a diagram illustrating the operation of the blocks in FIG. 3; Description of symbols of main parts: 11... Spindle servo, 12... Spindle motor, 13... Recording disk, 21... Variable frequency dividing circuit, 27... Control circuit.

Claims (1)

[Claims] 1. A recording method for a disc-shaped recording medium in which information is recorded as concentric or spiral information recording tracks, wherein the radius of curvature of the information recording track in the recording area of the recording medium is a predetermined value. A recording method characterized in that recording is performed so that the linear velocity of the recording track is constant in the following ranges, and the rotational angular velocity is recorded as constant in the range where the radius of curvature exceeds the predetermined value. 2. The information includes a predetermined periodic signal, and in the range where the rotational angular velocity is recorded as constant, the information is recorded as an angular velocity such that the synchronization signals are aligned and arranged on substantially the same radius line. A recording method according to claim 1, characterized in that: 3. The recording method according to claim 1 or 2, wherein the information signal is a video format signal, and the synchronization signal is a horizontal synchronization signal.