JPH0145155B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a recording beam feed pitch control circuit for an optical disk recording device.

In optical disk recording devices, etc., it is necessary to perform constant linear velocity recording, and for this purpose, the diameter information at the current position of the recording beam is converted into a target frequency for controlling the recording beam feed speed, and the recording beam is sent to that target frequency. It has been considered to phase control the rotation of the motor to obtain the required feed pitch. However, this method has the disadvantage that errors in the feed pitch due to mechanical errors in the feed mechanism accumulate, and the current position of the recording beam cannot be accurately controlled.

The present invention has been made to solve this problem, and calculates the diameter that should be sent by integrating the amount of rotation of the rotating spindle of the turntable, and calculates the feed pitch based on the difference between this and the current position of the light beam. The purpose of this correction is to eliminate errors in the current position.

The present invention will be explained in detail below according to one embodiment. The figure shows one embodiment of the invention. The current position of a feed stage 2 attached to a recording beam feed mechanism 1 (not shown) is read by a linear scaler 3 and converted into digital data, which is then added to an adder 9 and an address converter 4. The output of address converter 4 is applied to memories 6 and 12. memory 12
The output of is applied to the control terminal of counter 13, and its output is applied to one input terminal of comparator 14. The output of comparator 14 is applied to drive motor 16 of turntable 15. 1 of drive motor 16
The rotation pulse is applied to the other input terminal of the comparator 14 via the frequency divider 22 and the frequency divider 19
added to. The output of memory 6 is applied to adder 7, whose output is applied to the control terminal of counter 10. The output of oscillator 17 is output to counters 10 and 1.
3 input terminal. The output of counter 10 is applied to one input terminal of comparator 11, and its output is applied to motor 21. One rotation pulse of the motor 21 is applied to the other input terminal of the comparator 11 via the frequency divider 20. The output of frequency divider 19 is applied to preset counter 18, whose output is applied to adder 9. Preset counter 1
The preset terminal 8 is grounded via a switch 23. The output of subtracter 9 is applied to adder 7 via level shifter 8. A motor 21 drives the feed mechanism 1.

The operation of the above configuration will be explained. In the figure, the diameter information read from the linear scaler 3 attached to the feed stage 2 is composed of 6 BCD digits, and the recordable range of the disk, 45.00 mm to 125.00 mm, is divided into 8000 points every 10 μm. It becomes data. Address converter 4
The data is converted into binary data and input to addresses in memories 6 and 12. The memory 6 contains 8000 points of frequency division ratio control data for dividing the frequency of the 4MHZ oscillator 17 to generate a target frequency, and the preset value of the down counter 10 is controlled by this data. The down counter 10 is an oscillator 17
The target frequency is generated by counting down, and when it reaches zero, a pulse is generated and the operation of returning to the initial value is repeated. This target frequency is phase-compared with the output obtained by frequency-dividing the one-rotation pulse from the feed motor 21, and the obtained phase error signal is converted into a DC control signal to control the phase of the feed motor 21. The feed stage 2 is operated by a feed motor 2 by a feed mechanism 1 consisting of a reducer with a predetermined reduction ratio and a feed screw.
It is driven by a driving force of 1.

Here, constant linear velocity control (CLV control) is assumed so that the feed pitch of the recording beam and the relative velocity between the recording beam and the disk are constant regardless of the pickup position. In this case, the data written to the feed motor memory 6 is frequency division ratio control data for the counter 10 that divides the frequency of the oscillator 17. Current target linear speed
Vs, target feed pitch Tγ (m), frequency division ratio Nc of one rotation pulse of the feed motor 21, reduction ratio G of the feed mechanism,
Assuming the screw constant Kn (mm/Rotate) and the oscillation frequency Fosc of the oscillator 17, the division ratio Sc of the counter 10 using the diameter information D as a parameter is Sc=π・D・Kn・Fosc/Nc・Vs・G・Tγ 8000 points of data are determined. In this way, a target frequency corresponding to the recording beam position is obtained from the counter 10, and the motor 21 is controlled to keep the feed pitch constant. Similarly, the data written to the rotating spindle memory 12 is data that determines the frequency division ratio S _R of the counter 13 to the oscillator 17. Now, if the frequency division ratio of the frequency divider 22 is N _R , then
Using the diameter information D (m) as a parameter, S _R =π·Fosc/ _NR ·Vs·D. By changing D from 45.00 mm to 125.00 mm, the frequency division ratio control data for the counter 13 for 8000 points is determined. In this way, a target frequency corresponding to the recording beam position is obtained from the counter 13, and the motor 16 is controlled to keep the linear velocity of the recording beam constant.

However, in reality, simply controlling the motor 21 to a predetermined speed will cause errors in the feed pitch due to mechanical errors in the feed mechanism. For this reason, such errors are prevented by adding the following control loop. That is, the frequency divider 19 counts one rotation pulse of the motor 16 which is controlled as described above and rotates at a constant linear velocity, and the preset counter 18 counts every N pulses.
Send data to. For example, if the pitch is 1.6μm, 250
If we were to send each book, the beam would have to travel 0.4mm in the radial direction. On the other hand, the preset counter 18 is closed in conjunction with a start button (not shown) to preset diameter information at the start, and thereafter the output of the frequency divider 19 is integrated to generate digital data of the current theoretical diameter. It is done as follows. This theoretical diameter information and the current diameter information are compared by a subtracter 9 to create error data.
This error data is shifted appropriately according to the level and added to the division ratio control data from the memory 6 for creating the target frequency to correct the target frequency data, and the motor 21 is adjusted so that the above error becomes zero. Control. With this configuration, recording can be performed according to the theoretical value without disturbing the average pitch.

In the above explanation, the case where the turntable is rotated at a fixed position and the recording beam is moved in the radial direction of the turntable has been explained, but this is not limited to this. It goes without saying that the recording beam irradiation position on the turntable may be moved by moving in the direction.

As described above, according to the present invention, the average value of the feed pitch of the recording beam for an optical disk can be controlled to a very accurately determined value.

[Brief explanation of drawings]

The figure shows one embodiment of the invention. 2...Feeding stage, 6, 12...Memory, 1
0, 13... Counter, 16, 21... Motor.

Claims (1)

[Claims] 1. A first phase control means for controlling the phase of the rotational speed of the turntable by a pulse signal having a frequency proportional to the rotational speed of the turntable, which is predetermined according to the irradiation position of the recording beam; and a second phase control means for controlling the phase of the movement speed of the irradiation position by a pulse signal having a frequency proportional to the movement speed of the irradiation position, wherein the second phase control means generates a reference frequency. a frequency divider that divides the output of the reference oscillator; a means for detecting the irradiation position to obtain current position data; and an address specified by the current position data to correspond to the current position data. a memory from which moving speed data of the irradiation position is read; means for obtaining error data by comparing target value data of the irradiation position obtained by integrating the rotation amount of the turntable with the current position data; means for correcting the movement speed data using error data to obtain corrected movement speed data; means for controlling the frequency division ratio of the frequency divider using the corrected movement speed data; and means for controlling the frequency division ratio of the frequency divider using the corrected movement speed data; 1. An irradiation position control device for a recording beam of a disk-type recording device, comprising: means for phase-synchronizing the rotation of a drive motor for moving the recording beam.