JP2000123374A - Method of measuring track pitch of disk - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for measuring a track pitch of a disk where signals are recorded at a constant linear velocity. SOLUTION: In this measuring method, a track pitch is measured by counting the number of tracks where a light beam crossed while an optical pickup 4 moves in accordance with the prescribed number of revolutions of a pickup feed motor 2 and obtaining a ratio of the number of the tracks to the number of tracks counted in the case of a disk 1 on which signals are recorded at a prescribed track pitch.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for measuring a track pitch of a disk on which a signal is recorded at a constant linear velocity.

[0002]

2. Description of the Related Art A disk player which performs a reproducing operation by reading out a signal from a disk on which information data such as music is recorded by a digital signal using an optical pickup has become widespread. One of them is a CD player.

As is well known, a disk used in such a CD player has one block (consisting of 98 frames) with a period of 1/75 second in addition to a main data signal such as music information. Is recorded, a sub-data signal called a sub-coding signal is recorded. Such a subcoding signal is composed of eight channels of P, Q to W channels, in which the P channel contains position index information indicating the position of the beginning of the song, and the Q channel has the starting point of the signal track. And the position index information indicating the absolute elapsed time, the elapsed time for each song, the song number, and the like.

[0004] Therefore, the CD player can perform an operation of detecting a position where a desired song or the like is recorded by using the position index information and performing a reproducing operation, that is, an operation called a search. Have been.
Such a search operation is performed by moving the optical pickup in the radial direction of the disc. Such a movement operation is an operation of moving the main body of the optical pickup at a high speed to near the target position, that is, a pickup feeding operation. And an operation of displacing the objective lens constituting the optical pickup, that is, a track jump operation.

[0005]

The search operation in the disc player is performed by calculating the number of tracks from the absolute time of the current position and the absolute time of the target position to the target position, and using the optical pickup in accordance with the number of tracks. It is performed by moving the CD-ROM player, and a high-speed search operation is required in the CD-ROM player. In order to perform the search operation at high speed, it is necessary to move the main body of the optical pickup to a position near the target position at high speed, but if the track pitch of the signal recorded on the disc is different, the moving position of the optical pickup Is greatly different from the target position.

An object of the present invention is to provide a method for measuring the pitch of a signal track recorded on a disk in order to quickly perform a search operation.

[0007]

According to the present invention, the number of tracks traversed by a light beam while an optical pickup is moved by a predetermined number of rotations of a pickup feed motor is counted, and a signal is recorded at the number of tracks and a prescribed track pitch. The track pitch is measured based on the ratio to the number of tracks counted in the case of a disk.

[0008]

FIG. 1 is a block circuit diagram of a disk player according to the present invention. In FIG. 1, reference numeral 1 denotes a disk on which signals are recorded at a constant linear velocity and which is rotated by a spindle motor (not shown); Reference numeral 2 denotes a pickup feed motor, which is constituted by a brushless motor. Reference numeral 3 denotes a feed screw which is driven to rotate by the pickup feed motor 2 and has a thread groove formed around the feed screw. Reference numeral 4 denotes a signal recorded on the disk 1 by irradiating a signal surface of the disk 1 with a light beam. This is an optical pickup for reading out a signal, and has an objective lens, a photodetector, and the like incorporated therein, and is configured to be moved in the radial direction of the disk 1 by rotation of the feed screw 3.

Reference numeral 5 denotes an RF signal amplifying circuit for amplifying an RF signal obtained from a photodetector incorporated in the optical pickup 4 and shaping the waveform, and 6 denotes a signal obtained via the RF signal amplifying circuit 5. The optical pickup 4 performs a focusing control operation for focusing a light beam of the optical pickup 4 on a signal surface of the disk 1 and a tracking control operation for causing the light beam to follow a signal track on the signal surface. The pickup control circuit performs a control operation of a track jump by a displacement operation of the objective lens. The operation is performed by controlling a movement of the objective lens.

Reference numeral 7 denotes a digital signal processing circuit which receives a signal output from the RF signal amplifying circuit 5 and demodulates various signals, and 8 denotes a digital signal processed by the digital signal processing circuit 7. Is a signal reproducing circuit to which a data signal is input, and is configured to output a data signal to the computer device 9.

A system control circuit 10 receives a signal demodulated by the digital signal processing circuit 7 and performs various operation controls in accordance with a switching signal output from the computer device 9. It is configured.

Reference numeral 11 denotes the pickup feed motor 2
This is a motor drive circuit for controlling the rotation drive operation of the motor, and is configured so that the operation is controlled by a motor control signal output from the system control circuit 10. The rotation control operation of the pickup feed motor 2 by the motor drive circuit 11 is performed by a position detection signal obtained from a detection element that detects the position of a rotor such as a Hall element provided in the pickup feed motor 2. It is configured to be performed based on

Reference numeral 12 denotes the pickup feeding motor 2
A buffer circuit 13 to which a position detection signal obtained from a position detection element of a rotor provided therein is input, and a pulse signal generation circuit 13 to which a position detection signal obtained through the buffer circuit 12 is applied, Is output to an output terminal.

The optical pickup 4 is moved in the radial direction of the disc 1 by the rotation driving operation of the pickup feed motor 2 by the motor drive circuit 11.
Such a movement operation is performed by a rotation operation of the feed screw 3. When the pickup feed motor 2 rotates, a position detection signal obtained from a position detection element of a rotor provided in the motor 2 is input to a pulse signal generation circuit 13 via a buffer circuit 12. As a result, a pulse signal corresponding to the position detection signal is output to the output terminal of the pulse signal generation circuit 13, and the pulse signal is input to the system control circuit 10.

The rotation speed of the pickup feed motor 2, that is, the rotation speed of the feed screw 3 and the optical pickup 4
Is proportional to the amount of movement of the system control circuit 1
By counting the number of pulse signals input to 0, the movement amount of the optical pickup 4 can be measured and set. On the other hand, when the optical pickup 4 is in a moving state, the number of tracking error signals obtained when a light beam projected from the optical pickup 4 crosses a signal track recorded on the disk 1. , The number of signal tracks can be counted.

Therefore, assuming that the amount of movement of the optical pickup 4 moved by the predetermined number of rotations of the pickup feed motor 2 is S and the number of tracks counted in the meantime is N, the relationship with the signal track pitch P is as follows. P = S /
N.

On the other hand, the track pitch of the CD type disk is specified to be 1.6 microns, and the disk is moved at a predetermined rotation speed of the pickup feeding motor 2 using a test disk on which signal tracks are accurately provided. Assuming that the moving amount of the optical pickup 4 to be performed is s and the number of tracks counted during that time is n, 1.6 = s / n.

The relationship between the track pitch and the number of tracks is as follows:
The number of tracks is counted by setting the relationship between S and s, which are the amount of movement of the optical pickup 4 moved by the predetermined rotation number of the pickup feed motor 2, as S = s, and counting the number of tracks. The track pitch can be determined by multiplying the inverse ratio to the number of tracks n by 1.6 μm, which is a prescribed track pitch.

[0019]

According to the present invention, the number of tracks traversed by a light beam while an optical pickup moves by a predetermined number of rotations of a pickup feed motor is counted, and a signal is recorded at the number of tracks and a specified track pitch. Since the track pitch is measured based on the ratio of the number of tracks counted in the case of a disc to be counted, that is, the track pitch can be measured without using the moving distance of the optical pickup, the Even if there is variation in the moving distance of the optical pickup, the moving distance of the optical pickup in each disc player does not differ between the prescribed disc and the disc to be measured, so the track pitch must be accurately measured. Can be done.

Further, in the present invention, a signal used for performing a predetermined number of rotation counting operations of the pickup feed motor is obtained from a Hall element incorporated in the pickup feed motor, so that the number of rotations is counted. As compared with the case where the means is provided outside the pickup feed motor, the configuration is simplified and the number of rotations can be accurately counted.

[Brief description of the drawings]

FIG. 1 is a block circuit diagram of a disc player according to the present invention.

[Explanation of symbols]

 Reference Signs List 1 disc 2 pickup feed motor 4 optical pickup 6 pickup control circuit 7 digital signal processing circuit 9 computer device 10 system control circuit 11 motor drive circuit 13 pulse signal generation circuit

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tadayuki Takei 2-5-5 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (72) Yoshitaka Ikeda 2-5- Keihanhondori, Moriguchi-shi, Osaka 5 No. 5 Sanyo Electric Co., Ltd. (72) Inventor Masanobu Uchikawa 2-5-5 Keihanhondori, Moriguchi-shi, Osaka F-term in Sanyo Electric Co., Ltd. 5D088 PP06 SS05 UU01 5D117 AA02 EE08 EE14

Claims (2)

[Claims] 1. A method for counting the number of tracks traversed by a light beam while an optical pickup is moved by a predetermined number of rotations of a pickup feed motor, and determining the number of tracks traversed by the track number and a specified track pitch on a disk. A method for measuring a track pitch of a disk, wherein the track pitch is measured based on a ratio to a number of tracks counted in a case. 2. The truck according to claim 1, wherein a predetermined number of rotations of the pickup feed motor are counted by a signal obtained from a Hall element incorporated in the pickup feed motor. Pitch measurement method.