JPS6391869A - Disk rotation control device - Google Patents

Abstract

PURPOSE:To shorten the time up to the recording/reproduction of a data after a track access is executed, and to shorten a total track access time, by controlling synchronously a track access and a disk rotation control. CONSTITUTION:At the time of the track access, a pulse corresponding to a moving direction and the moving stroke of an optical head is brought to count-up or count-down by an address counter 1, a reference speed signal corresponding to the address of the present position is generated from a reference speed generator (ROM 2 and D/A 3), and the rotational speed of a disk is controlled. In such a manner, after an optical head reaches a target track, when the difference between reference speed and disk rotational speed becomes below a prescribed value, a phase difference between a read clock read from the disk, and a reference clock is detected by a detecting circuit 8, and a phase control is executed. As a result, the track access and the disk rotation control can be synchronized, and with respect to each track, the disk can be controlled quickly to optimum rotational speed.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an optical information recording and reproducing device that uses optical means to record information on a recording medium or to reproduce information that has already been recorded. , and particularly relates to a disk rotation control device.

[Conventional technology]

An optical information reproducing device that uses a laser beam as a light source and modulates the laser beam with a pulsed signal from an external information source to record binary information on a recording medium on a disk, or to read information that has already been recorded. In order to accurately record or reproduce information, focus control is performed so that the surface of the recording medium is always at the focal point of the condenser lens 1111. In addition, tracking position control of a laser beam spot with respect to an information track during recording or reproduction of information is usually performed by determining the optimum width for the beam spot on the recording medium, and
By providing a guide groove with the optimum depth for the wavelength of the laser used,
Tracking control is performed so that the minute spot follows the guide groove.

In addition, the rotation of a disk is generally controlled so that its rotational speed is a constant number, and for some applications, the circumferential speed of each track in the disk radial direction is controlled to be constant. The rotation speed of the disk is controlled in units of tracks or blocks.

[Problem that the invention seeks to solve]

By the way, when the rotational speed of the disk is constant, the recording density at the outer circumference of the disk is lower than when the circumferential speed of the track is constant, so the capacity that can be recorded on the disk is significantly reduced. For this reason, the disk capacity is increased by controlling the linear velocity to be constant so that the circumferential speed for each trunk in the radial direction of the disk is constant, thereby making the recording density on each track constant. However, when performing constant linear velocity control, it is difficult to synchronize the position of the optical beam in the disk radial direction and the disk rotational speed during track access. After accessing, actually recording the disk, or
This has the disadvantage that it takes time to read data, increasing the total track access time.

SUMMARY OF THE INVENTION An object of the present invention is to provide a disk rotation control device that eliminates the above drawbacks and can shorten the total track access time by synchronously controlling the trunk position and disk rotation speed during track access.

[Means for solving problems]

The disk rotation control ALL device of the present invention includes an address counter that indicates a relative position from a reference position in the disk radial direction, and a reference that generates a reference rotation speed signal corresponding to the radial position of the disk in response to the output of the address counter. a speed generator, a speed error detection circuit that calculates the difference between the rotational speed signal of the disk and the reference speed signal to generate a speed error signal, and a phase difference between the read clock and the reference clock detected from the disk. and a drive circuit that receives the rotation error signal or the phase error signal and rotates the disk rotation motor. The address counter is counted up or counted down by a movement pulse corresponding to the movement direction of the disk in the radial direction and the movement stroke, and the disk rotation motor is rotated in a manner suitable for the radial direction of the disk where the light beam is located. The present invention is characterized in that the speed is controlled, and then, in a state where the rotation error signal is below a certain value, the phase of the disk rotation motor is controlled by the phase error signal.

[Effect]

When accessing a track by moving the optical head, an address counter counts up or down pulses corresponding to the moving direction and movement stroke of the optical head, and generates a reference speed signal corresponding to the currently located address. is generated by a reference speed generator, and speed control is performed so that the rotational speed of the disk follows the reference speed signal. In this way, after the optical head reaches the target trunk, when the speed error signal representing the difference between the reference speed and the disk rotational speed falls below a certain value, the phase difference between the read clock read from the disk and the reference clock is detected. Then, the disk is driven by the phase error signal, and phase control is performed. By doing so, track access and disk rotation control can be synchronized, and the disk can be quickly controlled to the optimum rotation speed for each track.

〔Example〕

FIG. 1 is a diagram showing an embodiment of the present invention.

In the figure, 1 is an address counter, 2 and 3 are R
OM and D/A converter, and these ROM and D/A converter constitute a reference speed generator. 5
8 is a speed error detection circuit; 8 is a phase error detection circuit; 9 is a switch that switches the outputs of the speed error detection circuit 5 and the phase error detection circuit 8; 4 is a switch switching circuit that controls switching of the switches; 6 is a power amplifier; 7 is a motor. Note that switch 9. Switch switching circuit 4
The power amplifier 6 constitutes a drive circuit that rotationally drives the motor 7.

Next, the operation of this embodiment will be explained.

When accessing a track, a forward pulse (FWD) indicates the moving direction of the optical head and a certain amount of movement.
pulse) or reverse pulse (RVS pulse)
is input to the address counter 1, and the address counter is amplified or counted down. The ROM 2, which receives the output of the address counter, stores a signal indicating the reference speed of rotation of the disk corresponding to the address of the head. Output a signal. The speed error detection circuit 5 calculates a speed error signal representing the difference between the reference speed signal and the disk rotational speed signal, and inputs it to the switch changeover circuit 4. In the switch switching circuit 4, when the speed error signal is larger than a certain value, the switch 9 is switched to the speed error detection circuit 5 side.
, a motor 7 is driven via a power amplifier 6, and the speed of the motor 7 is controlled so as to follow a reference speed. By doing this, the rotational speed of the disk is controlled as the optical head moves during track access.

In this way, the optical head is positioned on the target track,
When the speed error signal generated from the speed error detection circuit 5 becomes less than a certain value, the switch 9 is switched by the switch changeover circuit 4, and the read clock and reference clock read from the disk output from the phase error detection circuit 8 are switched. The motor 7 is driven by the phase error signal between the two.

By doing this, the phase of the disk is precisely controlled to the optimum rotational speed corresponding to the track on which the optical head is located.

〔Effect of the invention〕

With the above-described configuration, track access and disk rotation control can be controlled in synchronization, and the time required to record/play data after track access can be shortened, reducing the track access time by 1. can be shortened.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of a disk rotation control device according to the present invention. 1... Address counter 2... ROM 3... D/A converter 4... Switch switching circuit 5... Speed error detection circuit 6... Power amplifier 7...Motor 8...Phase error detection circuit 9...Switch

Claims (1)

[Claims] (1) An address counter that indicates a relative position from a reference position in the disk radial direction; a reference speed generator that receives the output of the address counter and generates a reference rotational speed signal corresponding to the radial position of the disk; a speed error detection circuit that calculates the difference between the rotation speed signal and the reference speed signal to generate a speed error signal; and a phase error detection circuit that calculates the phase difference between the read clock and the reference clock detected from the disk and outputs a phase error. It is composed of an error detection circuit and a drive circuit that receives the rotational error signal or the phase error signal and drives the disk rotation motor to rotate. , the address counter is counted up or down by a movement pulse corresponding to the movement stroke, and the speed of the disk rotation motor is controlled to a rotation speed suitable for the radial position of the disk where the light beam is located; A disk rotation control device characterized in that the phase of the disk rotation motor is controlled by the phase error signal when the rotation error signal is below a certain value.