JPH0388133A - Detecting system for moving quantity of light beam - Google Patents

Abstract

PURPOSE:To decrease the influence of a preformat, etc., and to exactly detect the moving quantity of light beams by counting the periods of a tracking position error signal and detecting the moving quantity of the light beams relative to an optical disk. CONSTITUTION:A tracking control signal is inputted via a switch 17 and an amplifier means 18 to an optical head actuator 19 by a tracking control means, by which the light beams 2, 3 are controlled. Timing is generated by a preformat (PF) recognizing means 20 and is stored in a memory means 21 when the light beam 2 passes the PF region on the optical disk 4. A selection signal 22 is generated from the means 21 by a switching signal 27 from a control means 26 and the input of a period detecting means 24 is switched by a switch 23 from the tracking position error (TE) signal 5 to the TE signal 6 by the light beam 3. A period detecting means 24 generates the clock pulses corresponding to the period of the signals 5, 6 and counts the pulses by a counter means 25. The relative moving quantity of the light beams 2, 3 with the optical disk 4 is detected.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to optical disc access in which a light beam for recording and reproducing information on an optical disc is moved to an arbitrary address position on a track of the optical disc. A light beam movement detection method for detecting the relative position of a light beam to a target [Prior art] When moving a light beam to an arbitrary information track on which information is to be recorded or reproduced in an optical disc device, first the light beam is moved to a target. A coarse seek operation is performed to move the light beam close to the track, then a precise seek operation is performed to read the address from the disk and accurately position the light beam on the target track.Finally, the disk waits until it reaches the recording/playback position on the information track. The access is completed by performing three operations.

As a method to achieve high-speed access to an optical disk, the track address where the light beam is located is read from the optical disk, the relative number of tracks to the target track is calculated, the seek stroke is set, and the track address of the light beam is traversed during the access operation. A method is to detect the amount of movement of the light beam during the seek operation by counting track crossings, detect the relative speed of the light beam and the optical disk at the same time, and move the light beam directly to the target track by controlling the speed. This is disclosed in Japanese Patent Laid-Open Publication No. 177640/1983 entitled "Track Access Device for Optical Disk".

In the above-mentioned conventional technology, a track-crossing pulse corresponding to the track-crossing of the light beam is generated by utilizing the periodic changes in the tracking position error signal that is optically detected when the light beam crosses the track on the optical disk. occurs,
By counting these track crossing pulses, the amount of relative movement between the light beam and the track of the optical disk is detected.

In the coarse access operation, in order to detect the amount of movement of the light beam with respect to the optical disk from the tracking position error signal, the access device disclosed in the above publication is used to directly move the light beam to an arbitrary target track for recording and reproduction. High-speed access operations are possible.

Another conventional technique that performs coarse seek while detecting the amount of movement of a light beam using a tracking position error signal detected from a disk is a device using a separate optical head, published by Nikkei Electronics 1988.4. 18N
o, 445 P, 211-P, 224 r 5.25-inch magneto-optical disk device, average access time less than 50+ ms'' article. Because the optical system has a separate optical head configuration, the access means configuration and optical head control method are different, but the difference is that the amount of movement of the optical beam is determined by detecting track crossing. This is equivalent to the conventional technology.

Furthermore, as a method of irradiating an optical disk with two light beams,
, 121-126 "Optical Head Using R2 Laser and Applications".

[Problem to be solved by the invention]

During a rough seek operation, which is the first stage of an access operation, when the light beam used to record and reproduce information passes through scratches on the disk, defects in the recording medium, and preformatted areas for adding address information to the information track, etc. , the reflected light of the light beam is disturbed. This disturbs the optically sensed tracking position error signal, leading to erroneous detection of track crossings from the tracking position error signal, resulting in an excessive number of track crossing pulses being generated relative to the actual track crossing, or , becomes too small. In the conventional technology, the amount of movement of the light beam is detected by counting track crossing pulses, so if the number of track crossing pulses does not match the number of track crossings of the light beam, the light beam moves away from the target track at the end of the seek operation. position on the track.

As described above, in the conventional technology, if a track counting error occurs during a seek operation due to a disturbance in the tracking position error signal, a track seek error will occur at the end of the seek operation. There was a problem to be solved in that a precise seek operation was required, and the time required for accessing the optical disk was increased.

An object of the present invention is to provide a method for detecting the amount of movement of a light beam that solves the above-mentioned problems when performing an access operation of an optical disk.

[Means to solve the problem]

In the present invention, when performing an access operation to move a light beam from a currently located track on an optical disc to a target track for recording/reproduction, the amount of movement of the light beam relative to the optical disc is calculated based on the amount of movement of the light beam on the optical disc. A method for detecting the amount of movement of a light beam by counting the cycle of a tracking position error signal that periodically changes when the optical disc is moved. Detects tracking position error signals from two or more multiple light beams, and stores the timing at which the multiple light beams pass through a portion in the preformat area that has a large optical effect on detection of tracking position error signals. At the same time, during the access operation, the stored timing is used to select a light beam that is less affected by optical disturbances, count the period of the tracking position error signal, and calculate the amount of movement of the light beam relative to the optical disk. It is characterized by detecting.

[Effect]

In the present invention, when performing an access operation, the amount of movement of the light beam relative to the optical disk is detected in track pitch units by counting the period of the tracking position error signal. At this time, two or more light beams are focused on the optical disk, and a tracking position error signal is detected using at least two of the light beams.

When a light beam passes through a preformatted area in which addresses and the like are recorded unevenly on the track of an optical disk, the tracking position error signal is disturbed as explained in the "Problem to be Solved by the Invention" section. Accurate light beam with reduced effects of pre-formatting by selecting a light beam that is not affected by pre-formatting or having a small effect and counting the period of the track position error signal. The amount of movement can be detected.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram of an optical disc device that implements a method for detecting the amount of movement of a light beam according to the present invention.

According to one embodiment of the present invention, in this optical disc device, two light beams 2°3 are focused from the optical head 1 onto the optical disc 4, and a tracking position error signal is generated for each of the light beams 2 and 3. Detects 5°6. The positional relationship between the light beams 2 and 3 on the optical disk 4 at this time is shown in FIG. 2. As shown in FIG. 2(a), the light beam 2 moves on the radiation 7 drawn from the center of the disk 4. However, it is assumed that the light beam 3 moves on a straight line 8 separated from the light beam 2 by a certain distance d. Also, FIG. 2(b).

As shown in (C), the two light beams 2.3 are directed to the same track 9 on the optical disc 4 or to different tracks 9.
It is assumed that the optical disc 4 is located above the optical disc 4 at a distance d in the circumferential direction.

As shown in Figure 3(a), the format on the optical disc 4 is such that one round of the optical disc 4 is divided into, for example, 17 sectors 10 at equal intervals, and at the beginning of each sector IO there is a format as shown in Figure 3(b).
Sector mark 1 indicating the start of sector IO as shown in
1, address information 12, mirror part 13, etc. are preformatted, and a data area 15 follows the preformat area 14. Note that FIG. 3(b) shows tracks t, i+1. Only the i+2 part is illustrated.

In an optical disc such as an RSO standard format, a tracking position error signal 5.6 is generated in a preformat area recorded with unevenness on the optical disc 4, particularly at the sector mark 11 in the preformat area 14 and the mirror part 13.
The disturbance is large, causing erroneous detection in detecting the amount of movement of the light beam by counting the period of the tracking position error signal 5.6. Note that the tracking position error signal 5 is transmitted by the light beam 2, and the tracking position error signal 6 is transmitted by the light beam 3.
It was detected by.

Therefore, in the embodiment shown in FIG. 1, the tracking control means 16 first controls the switch 17. A tracking control signal is input to the optical actuator 19 via the amplifying means 18, and the optical beam 2.3 is controlled to follow the track 9 on the optical disc 4.Next, the optical beam 2 is controlled to follow the track 9 on the optical disc 4.
When the light beam 2 passes through the preformat area 14 above, the preformat recognition means 20 generates a timing for the light beam 2 to pass through the preformat area 14, and the timing storage means 21 determines when the light beam 2 is preformed for one revolution of the optical disc 4. The timing of passing through the format area 14 is stored.

During the access operation, the storage operation of the timing storage means 21 is stopped by the switching signal 27 output from the access control means 26, the selection signal 22 is generated from the information stored in the timing storage means 21, and the light beam is preformatted. The switch 23 changes the input of the period detection means 24 from the tracking position error signal 5 of the light beam 2 to the tracking position error signal 6 of the light beam 3 at the timing of passing the sector mark 11 in the area 14 and the mirror part 13. The switching zero period detection means 24 generates a track cross pulse corresponding to the period of the tracking position error signal 5.6 by a method such as determining the polarity of the input tracking position error signal 5 or 6, and performs counting. By counting the track cross pulses by means 25, the amount of movement of the light beams 2 and 3 relative to the optical disk 4 is detected.

Furthermore, in the embodiment shown in FIG. 1, the access operation is performed by inputting the amount of movement of the detected light beam to the access control means 26, but the control method of the access operation is not a subject of the present invention, and therefore will not be explained. is omitted.

Here, as shown in FIGS. 2(b) and 2(c), if the two light beams 2 and 3 are disposed offset by a distance d in the circumferential direction of the optical disc 4, the result will be as shown in FIG. 4(a).

As shown in (b), the influence of the two light beams 2 and 3 passing through the preformat area 14 shifts the timing at which the tracking position error signals 5 and 6 appear, so it is difficult to determine the polarity of the tracking position error signals. When generating a track cross pulse, the period of the tracking position error signal during the period in which the light beam 2 passes through areas with large optical disturbances such as the sector mark 11 and the mirror part 13 in the preformat area 14 is calculated. By using the tracking position error signal 6 detected from the beam 3, it is possible to reduce the influence of disturbances in the optical tracking position error signal 5 in the preformat area 14 on the detection of the amount of movement of the light beam, and to ensure accurate light beam detection. The amount of movement can be detected.

〔Effect of the invention〕

As described above, by using the light beam movement amount detection method of the present invention, it is possible to reduce the influence of the preformatted area on the detection of the light beam movement amount with respect to the optical disk, and it is possible to accurately detect the light beam movement amount. becomes. Therefore, by applying the present invention to the access operation in the optical disk device shown in the prior art, it is possible to reduce seek errors in coarse seek operations and shorten the time required for precise access, making it possible to realize high-speed access operations. Become.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an optical disk device that implements the light beam movement detection method of the present invention, FIG. 2 is a diagram illustrating the positional relationship between the light beam and the track on the optical disk, and FIG. 3 is a diagram of the optical disk. FIG. 4 is a diagram illustrating an example of a format. FIG. 4 is a diagram illustrating the influence of a preformat area on a tracking position error signal detected by two light beams. 1... Optical head 2.3... Light beam 4... Optical disk 5° 11, 12, 13, 14, 15, 16, 18, 19, 20, 21, 24, 25, 26・・Tracking position error signal・Sector mark・Address information・Mirra part・Preformat area・Data area・Tracking control means・Amplification means・Optical held actuator・Preformat recognition means・Timing storage means・Period detection means・Counting Means/access control means

Claims (1)

[Claims] (1) When performing an access operation to move the light beam from the current track on the optical disk to the target track for recording/reproduction, the amount of movement of the light beam relative to the optical disk is determined by the amount of movement of the light beam on the optical disk. This is a method for detecting the amount of movement of a light beam by counting the period of a tracking position error signal that changes periodically. A tracking position error signal is detected from each of the plurality of light beams, and the timing at which the plurality of light beams passes through a portion having a large optical influence on the detection of the tracking position error signal in the preformat area is memorized. At the same time, during the access operation, the stored timing is used to select a light beam that is less affected by optical disturbance, and the period of the tracking position error signal is counted, and the amount of movement of the light beam relative to the optical disk is calculated. A method for detecting the amount of movement of a light beam.