JPS59223950A - Method for controlling seek of optical disk - Google Patents

Abstract

PURPOSE:To easily control a seeking movement for an optical disk and to make positioning to an aimed track possible with less errors by performing eccentric movement follow-up control of the optical disk by optical fine seek in the course of rough seek control by means of an actuator. CONSTITUTION:Upon receiving a seek command, a rough seek controlling and driving circuit 8 performs rough seek by controlling an actuator 9. During the period of the rough seek, an optical axis forefront controlling and driving circuit 4 receives an input signal from an AND circuit 2 which calculates AND under a condition where the seek command and a signal from an eccentricity storing memory 1 are inputted, and the circuit 4 is switched to the eccentricity following-up control in accordance with the information of the memory circuit 1. When the seek command does not exist, another AND circuit 7 receives an input signal from a NOT circuit 6 which outputs under a condition where no seek command exists and the output signal (track following-up error signal) of a photoreceptor amplifier 14 in accordance with a reflecting light from a recording medium 10 and calculates AND. When received the output signal through an OR circuit 3, the optical axis forefront controlling and driving circuit 4 is switched to the track following up (fine seek) control. Therefore, rough seek can be performed without considering the eccentricity.

Description

Detailed Description of the Invention (a) Technical Field of the Invention This invention relates to a control method for positioning a light beam to a target track on an optical disk, which is a recording medium, and relates to a shearing control method for an optical disk that takes into consideration the influence of eccentricity of the optical disk. .

(b) Background of the technology The track spacing on a normal optical disk is approximately 1.6 μm to 2.0 μm.
0 μm, and therefore optical disks have the characteristic of being able to perform extremely high-density recording compared to other types of memory. However, the eccentricity of the tip disk is from several tens of micrometers to several hundred micrometers, and positioning of the light beam to the target trunk requires extremely fine control technology compared to other disk-type memories.

(C) Prior Art and Problems There are currently two general methods of seek control for positioning a light beam to a target track on an optical disk.

One is a two-step method in which a coarse seek is performed by reading a reference point on an external scale, and a fine seek is performed on the light beam by controlling the optical axis tip to position the light beam to the target track. This is a method of positioning a light beam to a target track by counting trunk crossing signals read as it traverses tracks on the disk.

Rough sheathing in the two-stage method moves to a rough position in units of about 20 to 30 μm.

The adjustment range for fine seek is up to about 100-odd micrometers, but since the eccentricity of the optical disk ranges from several tens of micrometers to several hundred micrometers, it is difficult to control the distance for coarse seek, and the influence of eccentricity at the start and completion of the seek operation is difficult. This has the disadvantage that a rough seek is performed again.

(d) Purpose of the Invention The object of the present invention is to provide a novel seek control method for an optical disk that eliminates the above-mentioned drawbacks. In particular, fine shear control, which is free from track following during coarse seek control, has already been measured. By switching to the drive based on the eccentricity stored in the memory and following the eccentricity while performing rough shear control, it becomes as if it were an ideal disc without eccentricity, making it easier to control the shear movement and reduce the vA difference. Therefore, it is possible to realize a seek control method for an optical disc that enables positioning to a target track with less noise.

(e) Structure of the Invention The present invention provides a seek control system in which an optical head is positioned on a target track on an optical disk as a recording medium using a two-step system of coarse seek using an actuator and fine seek using an optical mirror or objective lens. This can be achieved by an optical disk seek control method characterized in that the optical disk is positioned to the target trunk with little error by performing eccentric movement follow-up control of the optical disk by fine seek during coarse shear control.

(f) Examples of the invention The present invention will be explained below with reference to the drawings.

FIG. 1 shows an embodiment of the optical disk seek control method according to the present invention.

In the figure, 1 is an eccentric storage memory circuit, 2 and 7 are AND circuits, 3 is an OR circuit, 4 is an optical axis tip control/drive circuit, 5 is a mirror, 6 is a negative circuit, and 8 is a coarse seek control/drive. Circuit, 9 is actuator, 10 is recording medium, 1
1 is a polarizing prism, 12 is a laser diode, 13 is a light receiving element, and 14 is a read amplifier.

This embodiment consists of an eccentricity storage memory circuit 1 that stores the eccentricity state of the recording medium 10, an AND circuit 2 that performs an AND calculation of the signal of the eccentricity storage memory circuit 1, and a seek operation command signal, and an AND circuit 2. The logical sum circuit 3 calculates the logical sum of the signal from the logical product circuit 7 and the signal from the logical product circuit 7.During a coarse seek operation, the eccentricity storage memory circuit 1 tracks the eccentricity of the recording medium 10, and during fine seek or track tracking, the optical axis Optical axis tip control/drive circuit 4 that performs tip control; Optical axis tip control/drive circuit 4
mirror 5 which controls the optical axis, a negation circuit 6 which outputs the condition that the seek operation command signal is not input to the AND circuit 7, and an input from the negation circuit 6 that controls the optical axis tip control/drive circuit 4 to control the optical axis tip. An AND circuit 7 that switches to control, a coarse seek control/drive circuit 8 that controls the actuator 9 based on a seek operation command signal, an actuator 9 that coarsely seeks the entire optical head based on commands from the coarse seek control/drive circuit 8, and information using a light beam. The output light from the laser diode 12 is guided to the recording medium 10 through the mirror 5, and the recording medium 10
a polarizing prism 11 that guides reflected light from the light receiving element 13;
Consists of a laser diode 12 that emits light for recording/reproducing information on the recording medium 10, a light receiving element 13 that receives reflected light from the recording medium 10, and a read amplifier 14 that amplifies the optical power received by the light receiving element 13. has been done.

In this method, the rough shearing control/drive circuit 8 controls the movement of the actuator 9 in response to a shearing operation command, and the actuator 9 reads an external scale graduated in units of about 20 to 30 μm and performs rough shearing. The optical axis tip control/drive circuit 4 receives the input signal from the AND circuit 2 which calculates the AND under the condition that the seek operation command signal and the signal from the eccentricity storage memory circuit 1 are input. Depending on the information, control is switched to drive the recording medium 10 by following the eccentricity of the recording medium 10.

Next, when there is no seek operation command signal, the recording medium 10 receives the input signal from the negative circuit 6 which outputs an output signal under the condition that no seek operation command signal is input, and the light beam from the laser diode 12 is reflected. 5. Mirror the reflected light. The light-receiving element 13 receives the signal from the polarizing prism 11, and the read amplifier 14 amplifies the signal (trunk tracking error signal).The AND circuit 7 calculates the AND.1! The optical axis tip control/drive circuit 4, which receives the output signal from the logic circuit 7 via the OR circuit 3, is switched to track following (fine seek) control of the recording medium 10.

Accordingly, coarse seek can be performed without considering the eccentricity of the recording medium 10.

(g> Effects of the Invention As described above, in the seek operation for positioning the optical head to the target trunk, the optical disk is designed to eliminate the influence of the eccentricity of the recording medium by synchronizing the optical beam with the eccentricity of the recording medium. This has the effect of providing a shear control method.

[Brief explanation of the drawing]

FIG. 1 shows an embodiment of the optical disk seek control method according to the present invention. In the figure, 1 is an eccentric storage memory circuit, 2 and 7 are AND circuits, 3 is an OR circuit, 4 is an optical axis tip control/drive circuit, 5 is a mirror, 6 is a negative circuit, and 8 is a coarse seek control/drive. circuit, 9 is an actuator, 10 is a recording medium, 1
1 is a polarizing prism, 12 is a laser diode, 13 is a light receiving element, and 14 is a read amplifier.

Claims (1)

[Claims] A seek control method in which a light beam is positioned on a target track on a target trunk on an optical disk as a recording medium by a two-step system of coarse seek using an actuator and fine seek using an optical mirror or objective lens, the coarse seek control method comprising: A seek control method for an optical disc, characterized in that the fine sheathing performs eccentric movement follow-up control of the optical disc.