JPH01211367A - Circuit for controlling drive for master disk recorder - Google Patents

Abstract

PURPOSE:To set a track pitch with high accuracy by dividing original clocks with 1st and 2nd dividers and respectively using the outputs of the 1st and 2nd dividers as the reference clocks of a rotation driving mechanism and feeding mechanism. CONSTITUTION:Original clocks generated from an original clock generating section 1 are divided into 1/N by means of a divider 2 and reference clocks CF are formed and divided into 1/M by a divider 3 and reference clocks CSP are formed. Then motor speed signals C'F which are proportional to the rotating speed of a head feeding motor 8 are phase-compared with the reference clocks CF at a phase comparator 4 and the rotating speed of the motor 8 is controlled by means of the phase error signal produced as a result of the comparison. Similarly, motor speed signals C'SP which are proportional to the rotating speed of a master disk rotating motor 9 are phase-compared with the reference clocks CSP at a phase comparator 5 and the rotating speed of the master disk rotating motor 9 is controlled. Therefore, even if the frequency of the original clocks changes, the frequencies of the reference clocks CSP and CF simultaneously change and the rotating speed of a master disk is always maintained in a fixed state and, as a result, the track pitch is maintained constantly.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a drive control circuit for a master recording device suitable for recording a desired signal on a master disc of an optical disc or the like.

[Conventional technology]

Optical discs are obtained by copying from a master disc on which signals have already been recorded. A device for recording signals on such a master disc has a rotation drive mechanism that rotates the master disc and a feed mechanism that moves a head.The master disc is attached to this rotation drive mechanism and rotated, and the head is moved in the radial direction of the master disc. By moving it, a signal is recorded on the master. A light beam modulated by a signal is emitted from the head onto the master disc, thereby forming a pit array corresponding to the signal on the master disc, thereby recording the signal.

In the rotation drive mechanism, the master disk is rotationally driven by a rotation motor. Further, in the feed mechanism, a head mounting table is screwed onto a rod-shaped screw, and the feed motor rotates this screw. The rotational force of the feed motor is converted into linear force by the screw, thereby moving the head in the radial direction of the master.

A motor speed signal generator is provided in the motor of the rotational drive mechanism or the feed mechanism, and a motor speed signal having a frequency corresponding to the rotation speed of the motor is generated. These motor speed signals are each compared in phase with a reference clock by a phase comparator, and the rotation speed of each motor is controlled according to the comparison result. As a result, each motor rotates in synchronization with the reference clock, and stable master rotation and head feeding are performed.

[Mysterious problem to be solved by the invention] By the way, in conventional master recording devices, since the rotational speed of the motor in the rotary drive mechanism and the feeding mechanism is different, a clock generator is provided for each, and a reference clock generator is provided for each. The clock was generated independently.

On the other hand, in recent years, with the demand for increasing the recording capacity of optical discs, attempts have been made to narrow the track pitch to improve the recording density. By the way, in order to increase the recording density in this way, it is necessary to set the track pitch with higher precision than in the past. For this purpose, it is necessary to greatly improve the frequency accuracy of the reference clock of the rotation drive mechanism and the feed mechanism.

However, there is a limit to the frequency accuracy of the reference clock, and if the reference clocks for the rotation drive mechanism and the feed mechanism are generated independently as in conventional master recording devices,
There is a problem in that a difference in frequency accuracy occurs between these reference clocks, making it impossible to set the track pitch with high precision.

Furthermore, in the case of the CLV (constant linear velocity) method, it is necessary to vary the rotational speed of the master depending on the position of the head in the radial direction on the master. For this purpose, the frequency of the reference clock of the rotation drive mechanism and the feed mechanism is changed according to the head position, and the oscillation frequency of each clock generator is changed according to the output of the head position detector. In this case, the response speeds of the respective clock generators to changes in the output of the head position detector do not necessarily match, and the frequency relationship of these reference clocks may be disturbed. In such a case, the accuracy of the track pitch will deteriorate.

SUMMARY OF THE INVENTION An object of the present invention is to provide a drive control circuit for a master recording device that solves these problems and allows the track pitch to be set with high precision.

Means for Solving the Problem] In order to achieve the above object, the present invention divides the original clock from a single original clock generator by first and second frequency dividers, The output of the first frequency divider is used as a reference clock for the rotary drive mechanism, and the output of the second frequency divider is used as a reference clock for the feeding mechanism.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of a drive control circuit of a master recording apparatus according to the present invention, taking the CLV system as an example, in which 1 is an original clock generation section, 2 and 3 are frequency dividers, and 4.5 is a phase comparator, 6.7 is an amplifier, 8 is a head feed motor, 9
is the master rotation motor, 10 is the screw, 11 is the head mounting table,
12 is a head position detection section.

In the figure, an original clock generating section 1 generates an original clock C. This original clock C is frequency-divided by a frequency divider 2 to 1/N to form a reference clock CF, and is also frequency-divided by a frequency divider 3 to 1/M to form a reference clock C3P.

On the other hand, a head mounting table 11 to which a head (not shown) is attached is screwed onto a screw 10, and this screw 10 is rotationally driven by the head feed motor 8. When the screw 10 is rotated by the head feed motor 8, the head mounting table 11 screwed thereon moves straight along the screw 10. The screw 10 is arranged along the radial direction of a master (not shown), and therefore the head moves in the radial direction of the master.

Further, the master disc rotation motor 9 rotates the master disc.

The head feed motor 8 is provided with a feed motor speed signal generator (not shown), which generates a motor speed signal C having a frequency proportional to the rotation speed of the head feed motor 8.
1F is the reference clock Cr from the frequency divider 2 and the phase comparator 4
The phase is compared.

The phase error signal detected by the phase comparator 4 is amplified by an amplifier 6 and then sent to the head feed motor 8 as a rotation control signal.
is supplied to As a result, the number of revolutions of the head feed motor 8 is controlled so that the frequencies of the reference clock CF and the motor speed signal C/ are equal. Similarly, the master rotation motor 9 is also provided with a master rotation motor speed signal generator (not shown), which generates a motor speed signal c' having a frequency proportional to the rotation speed of the master rotation motor 9.
The phase of sp is compared with the reference clock csr from the frequency divider 3 by the phase comparator 5. The phase error signal detected by the phase comparator 5 is amplified by an amplifier 7 and then supplied to the master rotation motor 9 as a rotation control signal. As a result, the reference clock csp and the motor speed signal C'8. The rotation speed of the master rotation motor 9 is controlled so that the frequencies of the master disc rotation motor 9 and the master disc rotation motor 9 are equal to each other.

The head position detection unit 12 detects the position of the head attached to the head mounting table 11 in the radial direction of the master disc, and adjusts the oscillation frequency (
That is, the frequency of the original clock C) is changed. In this case, the variation characteristics of the oscillation frequency of the original clock generator 1 are adjusted so that the relative velocity (i.e., linear velocity) between the head and the master is constant no matter where the head is located in the radial direction of the master. A frequency division ratio N of frequency divider 2 and a frequency division ratio M of frequency divider 3 are set.

Therefore, the linear velocity between the head and the master is x (m/m/
5ec), and the track pitch on the master is P (m)
Then, the head moves r (m
) The rotational speed R (Hz) of the master disc at the position is as follows, and the head feed speed v (m/5ec
) becomes V=RXP...river (2).

That is, the feed speed V of the head is proportional to the rotation speed of the master. In the CLV method, since the linear velocity X is constant, the formula (
11, (21, it is necessary to change the rotational speed R of the master and the feed speed V of the head in accordance with the position r of the head in the radial direction of the master.

By the way, the rotation speed R of the master is proportional to the rotation speed of the master rotation motor 9, and the motor speed signal C'8. The frequency is proportional to the rotation speed of the rotary motor 9. Therefore, R=A−C'5p (A=proportionality coefficient) (3). Similarly, the head feed speed V is proportional to the number of rotations of the head feed motor 8, and the frequency of the motor speed signal C/ is proportional to the number of rotations of the head feed motor 8. Therefore, v=B-Cr' (B=proportionality coefficient) (4). Also, from the control of the rotation motor 9 and the feed motor 8 explained earlier, CAPyoC'sp* Cr =C'F...
...(5), so these motor speed signals CSr
The relationship between ' l CF· and the original clock C is as shown in the following equation.

C=M-C'5P=N-C' F......(6)
Therefore, from equation (6), even if there is an error in the original clock C, the motor speed signal C'SP+C'F will also have an error at the same rate as the original clock C.
From equations (3) and (4), it follows that there is an error in the same proportion between the rotational speed R of the master and the feed speed V of the head, and no error occurs in the track pitch. For example, the original clock C
Let R be the rotational speed of the master disc when there is no error in , and V be the feed speed of the head, then the track pitch P is given by the above equation (2): ■ P=□ (7).

Now, if there is an error in the original clock C, and the rotational speed R' of the original disc at that time is R'=R+ΔR...(8), then the head feed speed V' will also be at the same rate. Since there is an error, it becomes . If the track pitch at this time is P', then R' R is obtained, which is equal to equation (7). In other words, the track pitch has no relation to the frequency accuracy of the original clock C.

Furthermore, the reference clock C3PI Cy is the original clock C
Therefore, even if the frequency of the original clock C changes depending on the head position, the frequency of the reference clock C3F+Cy changes at the same time. Therefore, the relationship between the rotational speed of the master disk and the feed speed of the head is always kept constant, and the track pitch is kept constant.

FIG. 2 is a block diagram showing a specific example of the original clock generating section 1 and the head position detecting section 12 in FIG.
3 is Magnescale, 14 is a microcomputer, 1
5 is a synthesizer.

In the figure, a magnescale 13 constitutes the head position detection section 12 in FIG. 1, and outputs a digital value representing the head position in the radial direction of the master.

The microcomputer 14 processes this digital value and outputs a digital control signal. The frequency of the synthesizer 15 is controlled by this digital control signal,
An original clock C that enables the CLV method as shown in FIG. 1 is output.

FIG. 3 is a block diagram showing another specific example of the original clock generating section 1 and the head position detecting section 12 in FIG.
15 is a synthesizer, 16 is a counter, 17 is a ROM
(read-only memory).

In the figure, a counter 16 constitutes the head position output section 12 in FIG. In this case, as shown in FIG. 1, a pulse is generated every time the head moves a certain distance, and the counter 16 increments this pulse by +1. Therefore, the count value of the counter 16 represents the head position in the radial direction of the master. This count value becomes the address value of the ROM 17. The ROM 17 stores data at each address, and the counter 16
The data at the address specified by the count value is read. The synthesizer 15 outputs an original clock C having a frequency according to the data read from the ROM 17. For this purpose, each address in the ROM 17 represents the head position in the radial direction of the master disc, and each data is stored by the synthesizer 15 using the original clock C having a frequency corresponding to the head position represented by the address where this data is stored. Its value is set so that it occurs.

FIG. 4 is a block diagram showing still another specific example of the original clock generating section l in FIG. 1, in which 18 is a D/A converter, and 19 is a V/F converter (voltage/frequency converter).
The parts corresponding to those in FIG. 3 are given the same reference numerals.

In this specific example, the synthesizer 15 is replaced by a D/
This uses an A converter 18 and a V/F converter 19.

In FIG. 4, when data is read from the ROM 17 as in FIG. 3, this data is transferred to the D/A converter 18.
The signal is converted into an analog signal and supplied as a control voltage to a V/F converter 19 such as a voltage controlled oscillator. V/
The F converter 19 generates an original clock C having a frequency corresponding to this control voltage. Therefore, in this specific example as well, an original clock C whose frequency changes depending on the head position in the radial direction of the original disc can be obtained.

In the specific examples shown in FIGS. 3 and 4, it is not necessary to perform initial settings to set the head at the reference position (for example, the innermost circumferential position or outermost circumferential position of the master) and reset the counter 16. Needless to say.

Although the embodiment described above was based on the CLV method, it can also be applied to the CAV (constant angular velocity) method, and in the same way, regardless of the frequency accuracy of the reference clock,
Track pitch errors can be eliminated. However, CA
In the case of the V method, the head position detection section 12 is not required,
Needless to say, it is necessary to keep the frequency of the original clock C constant.

Furthermore, by frequency-dividing the original clock C and synchronizing the clock of the recording signal with it so that this clock has a predetermined frequency division relationship with the original clock C, in the case of the CLV method, Even if there is an error in the frequency of the original clock and an error occurs in the rotation period of the master or the head feed speed, the pit interval of each track is determined by the frequency ratio of the recording signal clock and the reference clock for rotation of the master. It is determined by , and becomes constant. In the case of the CAV method, bits can be arranged in the radial direction of the master between each track of the master. As a result, there is a frequency error in the original clock,
Even if there is an error in the rotation period of the master or the feed speed of the head,
The number of clocks on each track is equal to each other, and if multiple sectors are provided on each track of the master disc, the same number of sectors can be provided on each track, and the number of clocks can be made equal on all sectors. can be aligned in the radial direction of the master.

In the above embodiment, the head is moved in the radial direction of the master disc, but conversely, the head is fixed and the master disc is moved so that the head moves relatively in the radial direction of the master disc. You can do it like this.

〔Effect of the invention〕

As explained above, according to the present invention, by rotating the motor based on the reference clock, the master is rotated and the head or the master is moved, regardless of the frequency accuracy of the reference clock. An excellent effect can be obtained in that the pitch of the track to be formed can be set to a predetermined value with high precision.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of a drive control circuit of a master recording device according to the present invention, and FIGS. 2 to 4 show specific examples of the original clock generation section and head position detection section in FIG. 1, respectively. It is a block diagram. 1...Original clock generation section, 2, 3...
Frequency divider, 4.5... Phase comparator, 8...
・Head feed motor, 9...master rotation motor. Figure 1 Figure 2 Figure 3 Figure 4

Claims (3)

[Claims] (1) A rotation drive mechanism that rotates the master disc, and a feed mechanism that moves the head or the rotation drive mechanism to which the master disc is attached in the radial direction of the master disc, and the head sends a desired signal onto the master disc. A master disc recording device configured to record an original clock includes an original clock generator, and first and second frequency dividers that divide the output original clock of the original clock generator, and the first frequency divider A drive control circuit for a master recording apparatus, characterized in that the output of the second frequency divider is used as a reference clock of the rotation drive mechanism, and the output of the second frequency divider is used as a reference clock of the feed mechanism. (2) In claim (1), the method further comprises means for detecting the head position in the radial direction of the master, and changing the oscillation frequency of the original clock generating section according to the detection output of the means. . A drive control circuit for a master recording apparatus, characterized in that a linear velocity between the head and the master is kept constant. (3) Claim (1) or (2), further comprising a third frequency divider that divides the frequency of the original clock from the original clock generation section, the third frequency divider A drive control circuit for a master recording apparatus, characterized in that the output of the clock is used as a reference clock for the clock of the desired signal to be recorded.