JPH04155656A - Optical recording/reproducing apparatus - Google Patents

Abstract

PURPOSE:To realize reproduction of signal at a predetermined track position through stabilized high speed searching operation by controlling the rotational speed of a disc quickly to a value corresponding to a predetermined track position. CONSTITUTION:A disc 1 recoding signals is inserted and rotated at a constant line speed by means of a spindle motor 6. Signals are picked up from the disc 1 by means of a pickup 2 and fed to a preamplifier 4 which then produces a reproduction signal. The reproduction signal is demodulated through a signal processing circuit 5 to produce an error signal for matching the frame synchronizing signal in the reproduction signal with a reference signal corresponding to the position of the pickup 2 produced in the processing circuit 5. The error signal is converted through a servo circuit 8 into an analog signal and processed through a spindle motor drive circuit 7. An appropriate voltage is then applied on a motor 6 thus controlling the disc 1 at a constant linear speed corresponding to the position of the pickup 2.

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Field of Industrial Application The present invention relates to an optical recording/reproducing apparatus that rotates a recording medium (disk) at a constant linear velocity.

(B) Conventional Technology When recording information on a disc such as an optical disc, it is more advantageous to record information at a constant linear velocity than at a constant angular velocity because the recording density can be increased.

However, the number of rotations of the disk differs depending on the position of the reading means. Therefore, even if the reading means is moved to a predetermined track at high speed, the signal cannot be reproduced unless the number of rotations of the disk reaches the predetermined number of rotations. Therefore, conventionally, when the position of the reading means changes significantly due to a search or the like, the gain of the rotation control means is controlled by changing depending on the moving direction of the reading means. In other words, when the reading means moves toward the center of the disk, a large acceleration voltage is applied to the rotational drive means by increasing the gain of the rotation control means, and when the reading means moves toward the outer circumference of the disk, a large acceleration voltage is applied to the rotation driving means. ,
By reducing the gain of the 4-turn control means, the deceleration voltage is applied to the 1-turn drive means along with the back electromotive force generated in the rotation drive means.

(c) Problems to be Solved by the Invention However, when the reading means changes significantly from the outermost circumferential position (innermost circumferential position) to the innermost circumferential position (minimum circumferential position) due to high-speed search, etc., the win of the rotation control means is Even if the number of rotations is increased (or decreased), the time required to fix the rotational drive means to a predetermined rotational speed becomes unstable, making it impossible to perform a stable high-speed search.

The present invention was devised in view of the above-mentioned difficulties, and by quickly controlling the disk rotation speed to a rotation speed corresponding to a predetermined track position, a signal can be reproduced at a predetermined track position through a reliable high-speed search. The purpose of the present invention is to provide an optical recording/reproducing device that can perform the following.

(d) Means for Solving the Problems The present invention provides a recording medium on which signals are recorded, and a reading means that moves along the radial direction of the medium and reads at least the signals recorded on the recording medium. An optical recording and reproducing apparatus comprising: a rotary drive means for rotating the recording medium; and a rotation control means for controlling the rotation drive means to rotationally drive the recording medium at a constant linear velocity. g) a rotation speed calculation means for calculating the rotation speed of the recording medium at the track position; and a rotation speed detection means for detecting the rotation speed of the recording medium based on a signal synchronized with the rotation of the rotation driving means; When the rotational speed of the recording medium calculated by the calculation means and the rotational speed of the recording medium detected by the detection means match, the rotational speed of the recording medium is determined.

(E) Effect According to the present invention, the rotation speed of the disk at the target track position is calculated, compared with the rotation speed detected at the current position, and the disk rotation speed is changed at the maximum acceleration.
Quickly control the disc rotation speed to the target position.

(v) Embodiment The figure is a block diagram showing an embodiment of the present invention. (1
] is a disk on which information is recorded in a predetermined format; (2) is a preamplifier serving as a reading means for optically reading information recorded on the disk (1);
The linear motor (3) reads the information on the disk (1) while reciprocating in the radial direction of the disk (1).The read information is amplified by the preamplifier (4) and input to the digital signal processing circuit (5). The digital signal processing circuit (5) demodulates the information read from the disk (1) and performs data processing such as error correction, and also provides CLV (Consta
nt Linear Velocity) control, that is, information for realizing control for rotating the disk (1) at a constant linear velocity with respect to the pickup (2). (6) is a spindle motor as a rotation drive means for rotationally driving the disk (1); (7) is a spindle motor drive circuit for rotationally driving the spindle motor (6); Rotationally driven by. (8) means that the rotation of the spindle motor (6) in the spindle motor drive circuit (7) is (
The rotation of disk (1) relative to pickup (2) is)
A servo circuit as a rotation control means that controls the linear velocity to be constant (CLV control), and uses information given from the digital signal processing circuit (5), specifically the disk (1).
The rotation of the spindle motor (6) is controlled so that the synchronization signal recorded by the pickup (2) is read at a constant cycle. In addition, the servo circuit (8
) performs movement control such as focus adjustment and tracking of the pickup (2). (9) is a rotation speed detection circuit that detects the rotation speed of the disk based on the rotation speed signal output from the spindle motor (6). (10) is a control unit that issues commands to control the pickup (2) and spindle motor (6) in the servo circuit in response to input from the digital signal processing circuit (5) and operation commands from input means (not shown). , is also a rotation speed calculation means for calculating the rotation speed of the disk at the target track position.

In the above configuration, a disk (1) on which signals have been recorded is inserted into a disk insertion section (not shown) and rotated at a constant linear velocity by a spindle motor (6). In this state, a signal is read from the disk (1) by the pickup (2), and this is processed by the preamplifier (4) to become a reproduction signal. The reproduced signal is processed by a digital signal processing circuit (5
) and generates an error signal so that the frame synchronization signal of the reproduced signal matches the reference signal generated by the digital signal processing circuit (5) according to the position of the pickup (2). The error signal is converted into an analog signal by the servo circuit (8) and processed by the spindle motor drive circuit (7), from which an appropriate voltage is applied to the spindle motor (
6) and the disc (1) is picked up by the pickup (2).
The rotation is controlled at a constant linear velocity depending on the position of the

Now, the linear velocity is V, the pitch between tracks is p, the radius at the recording start position is ro, the radius at the target position is r, the playback time from the recording start position is t, and the rotation speed of the disc is R.
Then, from the total area of recording tracks from ro to r, pvt=πr! −πrゎ′...■ and v=2 π rR...■ hold true. Furthermore, if the number of tracks from ro to r is ga, then pn=r-ro...■ Since n is obtained from equations (1) and (2). In addition, r and R are represented by formula (2) and formula (2), respectively.

Now, when the control unit (10) is instructed to search for a target track, it determines the number of tracks from the current position to the target position (formula ■), the radius at the target position (formula ■), and the number of rotations at the target position (formula ■). ) are calculated sequentially. Next, since the current playback position information is held in the signal processed by the digital signal processing circuit (5), the optimal acceleration ( (or deceleration) calculate the starting rotation speed. When the control unit (10) commands the servo circuit (8) to rotate the disk, the servo circuit (8) drives the linear motor to move the pickup (2) to the target position and at the same time monitors the disk rotation speed. control the spindle motor drive circuit (7) so as to change the disk rotation speed at maximum acceleration while In the circumferential direction, control is performed to accelerate the disc rotation speed). At this time, the spindle motor (6) outputs a rotational speed signal synchronized with the rotation, and the rotational speed detection circuit (9) detects this signal to detect the disk rotational speed. Control part (10)
When the disc rotational speed detected by the rotational speed detection circuit (9) matches the calculated acceleration (or deceleration) starting rotational speed, it accelerates (or decelerates) at the maximum acceleration, and - matches the calculated predetermined rotational speed. Acceleration (or deceleration) ends when In this way, it is possible to quickly control the disc rotational speed to near the target position. Thereafter, the control unit (10) sends a CLV control command to the digital signal processing circuit (5) to shift to normal rotational speed control with a constant linear velocity, and control the rotational speed to a predetermined rotational speed.

Note that the pickup (2) serving as the reading means may have the function of not only reading information recorded on the disc but also writing information onto the disc.

(G) Effects of the Invention As is clear from the above explanation, the present invention compares the disk rotation speed detected by the rotation speed detection circuit and the disk rotation speed at the target position calculated by the control unit, and determines that the two match. When the spindle motor (6) accelerates (or decelerates)
The rotational speed of the disk is quickly controlled to near the target position, and then the rotational speed can be controlled to a predetermined rotational speed by CLV control, thereby enabling high-speed access.

[Brief explanation of drawings]

The figure is a block diagram illustrating a positional embodiment of the invention. (1)...disc, (2)...pickup,
(3)...Linear motor, (4)...Preamplifier, (5)...Digital signal processing circuit, (6)...
... spindle motor, (7) ... spindle motor drive circuit, (8) ... servo circuit, (9) ...
...Rotation speed detection circuit, (10)...Control unit.

Claims (1)

[Claims] (1) a recording medium on which a signal is recorded, a reading means that moves along the radial direction of the recording medium and reads at least the signal recorded on the recording medium, and a rotational drive means that rotationally drives the recording medium; an optical recording/reproducing apparatus comprising: rotation control means for controlling the rotation driving means to rotationally drive the recording medium at a constant linear velocity; and a rotational speed detection means for detecting the rotational speed of the recording medium based on a signal synchronized with the rotation of the rotation driving means, the rotational speed of the recording medium calculated by the rotational speed calculation means and the detection means. An optical recording/reproducing apparatus characterized in that when the rotational speed of the recording medium detected by the above-mentioned rotational speed matches the rotational speed of the recording medium, the rotational speed of the recording medium is controlled to a predetermined rotational speed.