JP2631135B2 - High-speed access method for constant-speed rotating disks - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION "Industrial application field" The present invention relates to the reflection of a digitized information from a carrier, such as a compact disc, on which pits are recorded on a track by irradiating a laser beam by irradiating the laser beam. The present invention relates to an access method for scanning and searching a desired track of the rotating disk by using an optical recording / reproducing apparatus configured to detect light and read recorded information. It is an object of the present invention to provide a method for shortening an access time required for moving an optical pickup to a target position by a track jump in a device for reproducing at a constant speed, that is, a linear speed.

[Prior Art] As shown in FIG. 3, the rotation of a rotary disk 1 is controlled by a rotary drive device 10 at a constant linear velocity. There is a request to search and move the reading device (optical pickup) 7, and when reading from information recorded on a disc, this is an indispensable technique for arbitrarily selecting a track.

Conventionally, in order to carry an optical pickup across a track to a target position, a key input means for presetting a target track number calculated from a distance of a disk to a target position of a track conforming to a constant linear velocity. The number of tracks determined from the access condition, that is, the time to move to the target track, by the certain target time setting device 2 is set in the time difference-track number conversion device 4, and the position control signal generation device 5 generates a track jump signal. A signal is sent from the optical pickup to a signal processor 8 which demodulates the read signal to convert it into a digital signal, calculates and outputs an absolute time, and converts the signal into a signal corresponding to the distance to be moved which has been preset. The absolute time from the start of the number of tracks specified by the target time setting device The signal is extracted from the lead-in area and compared with the signal of the current position of the optical pickup from the signal processing device with respect to time. Based on the output signal of the time comparison device 3, the absolute time difference stored in the internal memory is converted into the number of tracks. A detection signal from a track crossing detecting device 9 which outputs a pulse along with a track crossing of an optical pickup to a position control signal generating device for generating a track jump signal from a time difference-track number converting device 4 for outputting the number of tracks determined from the table. Are added to the position control signal generator 5.

The detection pulse signal of the track crossing detection is used for controlling a pickup position control device that controls the reading device.

By the way, the time difference track number conversion device uses a CLV system in which the circumferential speed, that is, the linear speed, is constant regardless of the track on the rotating disk, and assuming a certain linear speed, a single point on the rotating disk is used. Absolute time corresponding to the distance to the target position is arbitrarily divided into groups, and when the time information recorded on the disc for each of the divided absolute time groups is zero, the absolute time is zero and the target position is reached. The number of tracks is summarized in a comparison table corresponding to each other, and based on this comparison table, it is determined where the absolute time of the current position and the absolute time of the target position belong to the absolute time group divided above. After verification, the number of tracks of the husband and her husband from the absolute time zero corresponding to the group is obtained.

Therefore, the difference in the number of tracks is used to generate a control signal for the pickup position control device 6 in the position control signal generation device 5 to move the reading device. If the time difference is within a certain range, the time comparison device stops the output of the position control signal generation device 5.

In the time difference-track number conversion device, the greater the number of divisions for grouping the comparison table of the number of tracks from absolute time zero to the target position, the more accurate the number of tracks from absolute time zero to the target position becomes. I ’ll get as close as possible,
If the linear velocity assumed at the beginning is different, after moving the optical pickup, it will be adjusted to the correction position, that is, each time it is reciprocated many times, it will come to the ultimate position while detecting the current position, Prolonged access time due to slow approaching motion is inevitable, which is a drawback in searching for a target track.

"Problems to be Solved by the Invention" Therefore, in the conventional method of accessing the target track of the rotating disk, in order to bring the optical pickup to be moved as close as possible to the ultimate position, a number of operations for detecting the current position each time are performed. In order to prevent the extension of the access time caused by repeated operations, the number of tracks to be moved is calculated by a quadratic equation from the absolute time by the reader and the absolute time at the time of moving to the target track. The optical pickup is moved quickly by the number of tracks to be moved, and the access time is greatly reduced.

[Means for Solving the Problem] According to the present invention, the information from the rotating disk read by the reading device is added to the time comparing device via the signal processing device, and the time corresponding to the target track number is set in advance to the target time. As long as it is preset in the device and the time difference is obtained in addition to the time comparison device and the solution of the quadratic equation is obtained by the time difference-track number calculation device under a constant linear velocity of the rotating disk, the ultimate movement is required. The number of tracks can be searched with a small error.

An embodiment of the present invention will be described below with reference to the drawings.

"Embodiment" FIG. 1 is a block diagram of a rotary disk recording / reproducing apparatus for explaining the present invention, and the same parts as those in FIG. 3 are denoted by the same reference numerals.

The configuration and operation of the recording / reproducing apparatus shown in FIG. 1 are the same as those of the recording / reproducing apparatus except for the time difference-track number calculating device 20 and the input / output relationship of signals.

First, the rotating disk has time data recorded along with a sound signal (data) from the inner circumference to the outer circumference. One of the time data (address) is a track time indicating the progress of each track number, and the other is time. One is divided into a disc time indicating the whole progress, but the disc time becomes zero when the audio information area is entered from the lead-in area, and the time increases with the reproduction of the audio information area. It has become. Therefore, assuming that the time when the time in the disk is zero is defined as absolute time zero, the number of tracks from this absolute time zero position to the point Ax and the sample of the absolute time at the point Ax are A ₁ , A ₂ ,. Ax from absolute time zero at Ax point
Number of tracks Nx up, the absolute time of Ax when the Tx, can be represented by ^{Tx = aNx 2 + bNx + c} ...... (1).

In order to determine the constants a, b, and c in the above equation (1), the sample numbers (N ₁ T ₁ ) and (N ₂ T ₂ ) of the number of tracks and the absolute time from the points A ₁ , A ₂ ... Tx = ANx ₂ + BNx + C (2) When the disc is set in the reproducing apparatus, the book (2)
When the number of tracks from the absolute time zero is obtained from the absolute time E of the target track and the absolute time F with respect to the current position of the reading device, which are input to the time difference-track number calculating device 20 in which the formula is obtained and stored once. ² + BNx + C Nx0 (3) F = ANx ² + BNx + C Nx0 (5) And becomes the number of tracks N from the current position to the target track becomes _{N = N E -N F ...... (} 7) the number of tracks is determined.

The above equation (2) is stored in the RAM until the rotating disk is replaced. FIG. 2 shows the relationship between the absolute time Tx and the number of tracks Nx from the absolute time zero.

Therefore, if a quadratic equation is created by substantially equal sampling for the entire rotating disk, a quadratic curve of the track and the absolute time can be set to an equation that is closest to the set disk on average. In other words, it means that the quadratic curve can follow a variation in track interval and a linear velocity different for each disk.

If the correct track crossing number N is known from the result of the above procedure, a direct search path can be opened.

[Effect] According to the high-speed access method for a constant linear speed rotating disk of the present invention, the relationship between the absolute time from the current position of the reading device to the target track and the number of tracks from the absolute time zero is represented by a quadratic equation. It can be expressed by a very approximate relational equation, and even if there is variation in the track-to-track dimensions, the desired number of tracks can be automatically obtained by calculation without any deviation as long as the reproducing apparatus is driven to rotate at a constant linear speed, and the reading apparatus is used. The access time of the optical pickup can be greatly improved.

[Brief description of the drawings]

FIG. 1 is a block diagram of a rotary disk recording / reproducing apparatus for implementing the access method of the present invention, FIG. 2 is a graph showing a relationship between absolute time and the number of tracks from zero absolute time, and FIG. It is an implementation circuit diagram. 1 ... Rotating disk, 2 ... Target time setting device, 3 ...
Time comparison device, 20: Time difference-track number calculation device, 5
...... Position control signal generator, 6 ... Pickup position controller, 7 ... Reader (optical pickup), 8 ...
Signal processing device, 9: Track crossing detection device, 10: Rotation drive device.

Claims (1)

(57) [Claims] An optical pickup should be moved to a target track, a signal based on an absolute time taken out by a signal processing device, and a signal obtained by a reading means of a rotating disk optically recording information. A signal from the time comparison device obtained by presetting the target time in advance and a signal obtained by the track crossing detection device are used to send a signal for controlling the movement of the optical pickup to the optical pickup position control device via the position control signal generation device. In the method used, the relationship between the absolute track time to the target track based on the constant linear velocity obtained by the time comparison device and the number of tracks corresponding to the difference between the absolute time obtained from the track crossing detection device of the reading device is Tx. = ANx ² + bNx + C (where Nx: number of tracks from absolute time zero to target position Ax, a, b, c: constants,
Tx: the absolute time of Ax), and these constants are obtained in advance by the least-squares method to obtain the number of tracks to be moved.