JPH0689550A - Optical disk device - Google Patents

Abstract

PURPOSE:To detect the radial position of a light spot on a disk regardless of the defect, etc., of the disk. CONSTITUTION:This device is provided with a rotation means 10 rotating an optical disk 1 having a spiral shape track, an optical head 2 casting a light spot on the track and a rotary synchronizing signal output means, etc., outputting a rotary synchronizing signal synchronized with the rotation of the optical disk 1. Further, this device is provided with a radial position detection means 11 counting the rotary synchronizing signal, and detecting the radial directional position of the light spot on the optical disk 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk device having a radial position detecting function of an optical spot irradiated on an optical disk.

[0002]

2. Description of the Related Art A conventional device of this type reads a track number recorded on a track of an optical disk in order to know the position of the light spot on the optical disk in the radial direction while the light spot follows the track of the optical disk. Was there.

[0003]

In the above-mentioned conventional techniques, the radial position of the light spot cannot be accurately known because the track number cannot be read due to a defect of the optical disk or the track number is misread. There was a problem. Therefore, it is an object of the present invention to provide an optical disk device capable of detecting the radial position of a light spot on an optical disk without being affected by a defect of the disk.

[0004]

In order to solve the above problems, the present invention provides a rotating means for rotating an optical disk having a spiral track, an optical head for irradiating a light spot on the track, and an optical disk for the optical disk. A rotation synchronization signal output means for outputting a rotation synchronization signal synchronized with the rotation, and a radial position detection means for counting the rotation synchronization signal and detecting the radial position of the optical spot of the optical disc by the count value are provided. It was configured.

[0005]

In the present invention, the radial position of the light spot on the disk can be detected by using the count value of the rotation synchronizing signal of the optical disk.

[0006]

1 is a block diagram of an optical disk device according to an embodiment of the present invention. In FIG. 1, a spiral track is formed on the surface of the optical disc 1, and information is recorded on this track. Laser light 3 is emitted from the optical head 2 onto the optical disc 1 to form a light spot on the optical disc 1. The emitted laser light 3 is reflected by the surface of the optical disc 1, and the reflected light returns to the optical head 2. For example, a two-divided photodiode is provided in the optical head 2, receives the reflected light from the optical disk 1, and outputs a current according to the amount of the received light. The current signal output from each of the two-divided photodiodes is converted into a voltage by the head amplifier 4 and input to the track difference signal circuit 5 and the track sum signal circuit 6. The track difference signal circuit 5 and the track sum signal circuit 6 are composed of operational amplifiers and the like. The track difference signal circuit 5 outputs a difference voltage of two voltages, and the track sum signal circuit 6 outputs a sum voltage of two voltages. The difference voltage and the sum voltage are AGC (Automatic
Gain Control) circuit 7, phase compensation circuit 8
Is output to the servo system circuit via. AGC circuit 7
Sets the required gain. The required gain fluctuates depending on the disturbance, but the AGC circuit has a function of controlling the gain according to the disturbance. The phase compensation circuit 8 is for improving the phase characteristic of the voltage signal. In the servo system circuit,
Tracking control, focusing control and the like are performed based on the input difference voltage and sum voltage. For example, in the case of tracking control, the position and the position of the light spot are controlled by detecting the direction and amount of deviation of the position of the light spot irradiated on the optical disc 1 from the track center by the difference voltage. By this control, the light spot can follow the track of the rotating optical disc 1.

The output from the track sum signal circuit 6 is also used as an information signal indicating the information recorded on the optical disc 1. The sum signal output from the track sum signal circuit 6 is I
It is input to the D detection system circuit 9. The ID detection system circuit 9 detects ID data from the sum signal. ID data detected
Data is sent to the disk radial position detection circuit 11. ID
The data includes the track number of the optical disc 1. The disk radial position detection circuit 11 normally extracts the track number from the ID data and outputs the track number. Since the track number is a unique number recorded on each track of the optical disc 1, it is possible to know which track the light spot is currently irradiated by detecting the ID data. That is, the position of the light spot in the radial direction can be known. The disk radial position detection circuit 11 includes a motor 10 for rotating the optical disk 1.
The disk rotation synchronizing signal from is also input. The disc rotation synchronization signal is a signal that is output in synchronization with the rotation of the optical disc 1, and for example, one pulse is output every one revolution of the optical disc 1.

FIG. 2 is a block diagram of the disk radial position detection circuit 11. First, the microcomputer 21 presets the track number (extracted from the ID data) at the time when the light spot starts tracking the track by activating the LOAD signal in the counter 22. At the same time when the light spot starts following the track, the microcomputer 21 activates the count enable signal. An AND gate 23 inputs a logical product signal of the count enable signal and the disk rotation synchronizing signal to the counter 22 as a clock. The counter 22 counts up the preset value each time the disk rotation synchronizing signal is input while the count enable signal is in the active state. Then, the count value is output.

In the state where the light spot follows the track, the position of the light spot in the radial direction moves by one track each time the optical disk 1 makes one revolution.
Therefore, if the preset value (track number at the start of track following) is incremented for each input of the disk rotation synchronizing signal, the track number of the track where the light spot is located can be known from the count value. . For example, if the track number is given such that the track number is incremented by 1 every time the track moves, and if the disk rotation synchronization signal is output every time the optical disk makes one rotation, the count value is the light spot at that time. It will be equal to the track number in which it is located.

The microcomputer 21 includes a switch 2
4 is controlled and the switch 24 is normally connected to the contact a side. Then, the microcomputer 21 is an ID data
When a normal track number is read from the computer, the read track number is output. When the track number cannot be read or is misread, the microcomputer 21 outputs a signal for switching the switch 24 and connects it to the contact b side. Then, the count value of the counter 22 is output as a track number.

The track number output from the disk radial position detection circuit 11 having the above-mentioned configuration is the control system 12.
Is output to. The control system here controls the light spot according to the radial position of the disc. For example, updating of the offset correction value for tracking, light emission power correction and pulse width correction of a laser diode for irradiating laser light, head runaway prevention control by detecting the outermost track, and the like can be considered.

If the track number is erroneously recognized, there is a possibility that the offset correction value for tracking to be updated, the light emission power value of the laser diode to be corrected, the pulse width value, etc. may be set to unsuitable values. However, according to the present embodiment, even if the track number is read incorrectly, the correct track number can be known from the count value.
The value will not be set to an inappropriate value.

[0013]

As described above, according to the present invention, even if the track number where the optical spot is following the track cannot be read or the track number is erroneously read due to a defect of the optical disk, the disk rotation synchronizing signal is read. By using, the disk radial position can be known. By utilizing this, there is an effect that the control according to the disc radial position of the light spot can be appropriately performed even when the track number cannot be read.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an optical disk device according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of a disc radial position detection circuit of an optical disc device according to an embodiment of the present invention.

[Explanation of symbols]

 1 Optical Disc 2 Optical Head 3 Laser Light 10 Motor 11 Disc Radial Position Detection Circuit 21 Micro Computer 22 Counter

Claims (1)

[Claims] 1. A rotating means for rotating an optical disc having a spiral track, an optical head for irradiating a light spot on the track, and a rotation synchronizing signal outputting means for outputting a rotation synchronizing signal synchronized with the rotation of the optical disc. And a radial position detecting unit that counts the rotation synchronization signal and detects the radial position of the optical spot of the optical disc on the basis of the count value.