SU1723584A1 - Method of searching data on optodisk - Google Patents

Abstract

The invention relates to the accumulation of information, in particular to methods of searching information on an optical disk medium, and can be used, for example, in an optical compact disc player, as well as in optical storage devices. To shorten the search time and increase the accuracy of information retrieval, the required amount of change in the position of the optical head and the value of change in the frequency of rotation of the optical disk are determined and changed simultaneously. A control signal for fine tuning the rotational speed of the optical disk in the desired position of the optical head is obtained by periodically averaging the signal reproduced from the optical disk with the required accuracy, for example, dividing it by 210-212.1.

Description

The invention relates to the accumulation of information, in particular to methods for searching information on an optical medium, and can be used, for example, in an optical CD player, as well as in optical storage devices.

A known method of searching information on an optical disc is performed by determining the predetermined position of the optical head, moving the optical head to a predetermined position with counting the number of tracks crossed by the head, executing fine adjustment to the predetermined position, and setting the required frequency of rotation of the disc after stopping the head in a predetermined position.

In this method, each time when searching for information, it is necessary to count the intersected tracks, which during operation becomes difficult due to the appearance of scratches and spears on the disk, which leads to search errors. In addition, after the head is installed at a predetermined position, it is necessary to perform a coarse and then fine adjustment of the disk rotation engine to the rotational speed vx necessary for this point. Since moving the head to a predetermined position of the pile and adjusting the motor of rotation takes about the same time, it takes double time to search for information.

The closest in technical essence to the present invention is a method of searching information on an optical disc, carried out by calculating the amount of movement of an optical head along the disk radius based on the current position and the desired one, moving the optical head

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for a calculated value, coarse adjustment of the rotational speed of the disk and fine-tuning it in accordance with the desired position of the optical head, changing the frequency of rotation of the disk in accordance with the signal obtained by processing the impulse signal reproduced from the disk, processing the signal by extracting the sync signal and measuring the duration of the selected signal .

The disadvantage of this method is the double expenditure of time for searching for information, since at first the optical head is moved to a predetermined position, and then the rotation frequency of the disk is set to correspond to the predetermined position of the head. In addition, the selection of the sync signal from the reproduced signal is hampered by external influences on the disk, which leads to a failure in information search.

The aim of the invention is to reduce the time and improve the accuracy of information retrieval.

In order to achieve this goal, in the method of searching information on an optical disc, at which the required amount of change in the position of the optical head along the radius of the optical disk from the current position to the desired position is changed, the position of the optical head is changed to the required value, the required value of change in the frequency of rotation of the optical disk is determined , to which the rotational frequency of the optical disk is first preliminarily changed, after which the rotational frequency is precisely adjusted in accordance with the pulse controller with with the signal reproduced from the optical disk in the desired position of the optical head, the required magnitudes of change — the position of the optical head and the frequency of rotation of the optical disk, respectively, are determined and changed simultaneously, and the control signal for fine tuning the frequency of rotation of the optical disk in the desired position an optical head is obtained by periodically averaging a pulsed signal reproduced from an optical disk with the required accuracy.

The drawing shows the block diagram of the device that implements the proposed method.

The device contains an optical disk 1, on which information is recorded in the form of a pulse-modulated (PCM) signal, a computational control unit 2, an optical head 3, a radial movement motor 4 of the optical head, a disk rotation engine 5, a converter 6 reproduced from the disk of the signal, the parameter meter of the converted signal, the driver 8 of the control signal, the circuit 9 of tracking the line speed of rotation of the disk. The control unit 2 consists of serially connected permanent memory circuit 10, arithmetic logic circuit 11, and a coarse motion control generator 12. The converter 6 of the signal reproduced from the disk consists of amplifier 15, limiter 16 of the signal for maximum and minimum, and frequency divider 17. Linear speed tracking circuit 9 consists of a low-pass filter 18, a switch 19 and a power amplifier 20.

The proposed method of searching information on an optical disc consists in using the computational control unit 2 to determine the required amount of change in position (A R) of the optical head 3 along the radius of the optical disk 1 from the current position (RT) in the desired (Rx). Simultaneously with the determination of AR, the magnitude of the change in the frequency of rotation of the disk (Av) is determined to conduct it in accordance with the desired position of the RX optical head. At the same time AR RT Rx, AV VT-vx. After determining AR and Av, change the position of the optical head and simultaneously change the frequency of rotation of disk 1 by the value of AR and Av, respectively, by applying signals to motors 4 and 5. The signal to radially moving the optical head to the motor 4 is fed through power amplifier 13 from the control signal generator 12 and the signal to the motor 5 of the disk rotation is fed through the power amplifier 20 from the power source -1) pit or HJnm depending on the direction of movement of the optical head, while the driver 12 of the control signal sets switch 19 to the appropriate position. After setting the optical head to the desired position RX and setting the frequency of rotation of the vx disk, which approximately corresponds to the desired position of the head, the frequency is fine tuned. A control signal for fine tuning the rotational speed of the disc is obtained by periodically averaging the pulsed signal reproduced from the optical disc with the required accuracy. For this, the pulse signal reproduced from the disk 1 by the optical head 3 is fed through the amplifier 15 to the limiter 16, where the limiting occurs

its maximum and minimum, from the output of the limiter, the signal enters the frequency divider 17, where it is divided multiple times, for example, by 210-212, resulting in averaging of the signal and conversion to periodic. A periodic signal (for example, a square wave) is fed to the parameter meter 7, which, in accordance with the measured parameters, outputs a corresponding pulse to the comparison unit of the fine control signal generator 8. From the output of the latter, the control signal is fed through a low-pass filter 18, the contacts of the switch 19 and the power amplifier 20 to the motor 5 of the disk rotation.

Claims (1)

The method of searching information on an optical disc, in which the magnitude of the change in the position of the optical head along the radius of the optical disk from the current position in the desired position is changed, changes the position of the optical head by the required value, determines the required value of the change in the frequency of rotation of the optical disk by which the frequency of rotation of the optical disc is first preliminarily changed, after which the rotational frequency is precisely adjusted in accordance with the pulse control signal, rendered from the optical disk in the desired position of the optical head, characterized in that, in order to reduce time and increase the accuracy of information retrieval, the required values for changing the position of the optical head and the frequency of rotation of the optical disk are respectively determined and changed simultaneously, and the control signal for precise adjusting the frequency of rotation of the optical disk in the desired position of the optical head is obtained by periodically averaging a pulse reproduced from the optical disk with the required accuracy clear signal. . L I-UfWfrt -4- UfjUfTfJ