JPS6182376A - Motor controller of digital disk player - Google Patents

Abstract

PURPOSE:To prevent an erroneous operation of motor control in case of tracking the part without an inter-track pit by inhibiting the control of the rotating speed of a disk drive motor with the aid of information for showing the line speed detected from the reproduction output of a disk when the reproduction output level of the disk is below the prescribed level. CONSTITUTION:A data signal SA read out from a disk 11 to a pickup element 12 is level-sliced by a signal processing circuit 13 to obtain a signal SB. With use of the reference signal from a reference signal generator circuit 15, a maximum inversion interval detection circuit 14 measures the inversion interval of the signal SB, and detects a frequency component having the maximum inversion interval. A motor control circuit 16 controls the rotating speed of a motor 17 so that the inversion interval can come to the prescribed value, and maintains the constant line speed of the pit string of the disk 11. When the level of the high frequency signal processed by the circuit 13 is below the prescribed value, a detection inhibition signal generator circuit 18 inhibits the detecting action of the circuit 14.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a motor control device for a digital disc player.

[Technical background of the invention]

In recent years, digital audio discs (DADs) have been developed, which convert audio signals into digital PCM as digital data signals and record them on discs using uneven bit sequences, and digital disc players that detect the pit rows of this disc and play back the original audio signals. has been done. By the way, in such a disc playback system, the above-mentioned pit string is recorded using a constant linear velocity method (CLV). For example, when tracking a bit string using an optical pickup method, the optical pickup element is internally recorded. The disk is driven such that its rotational speed decreases as it moves from the periphery to the outer periphery. Therefore, in such a disc playback system, for example,
A synchronization signal synchronized with each frame of the digital data signal is extracted from the frequency component of the digital data signal read from the disk, and the rotational speed of the disk drive motor is controlled so that this synchronization signal has a predetermined frequency. ing. In addition, when a synchronizing signal cannot be obtained, such as when the motor starts rotating or when the pickup element is forced to move at high speed, the maximum frequency component of the digital data signal read from the disk is It is configured to detect a frequency component having an inversion interval, and to control the rotational speed of the disk drive motor so that the interval between the frequency components becomes a predetermined value.

This point is described in Japanese Patent Application No. 102826/1982 filed by the applicant on June 15, 1982.

[Problems with background technology]

However, with the above configuration, when the pickup element is moved at high speed from the inner circumference to the outer circumference in order to find the beginning of a song, for example, the signal is dropped in areas where there are no gaps between tracks, and the maximum The reversal interval is the original value υ
It also becomes long. Therefore, in such cases,
There was a drawback that the rotational speed of the disk drive motor could not be accurately controlled.

Figure 3 shows this situation. In the figure, SA
are digital data signals reproduced from the disk by the pickup element, and t and b are high frequency signals.

In this high frequency signal sA, the portion where the level is decreasing corresponds to the portion where there is no bit between tracks. When detecting the maximum inversion interval, it is generally performed after level slicing the high frequency signal sA and returning it to the digital data signal sB. In this case, the slice level L beam, ,L,
As shown, it changes in accordance with the level fluctuation of the high frequency signal RA.

However, in a portion where there are no bits between tracks, the reproduction output level of the disc becomes smaller than the variable range of the slice level, and the digital data signal SR after slicing does not include any reproduction information of the disc. As a result, the digital data signal 5Bvc includes a frequency component having an inversion interval larger than the actual maximum inversion interval, and the motor control for keeping the linear velocity constant will malfunction.

[Purpose of the invention]

The present invention has been made to address the above-mentioned circumstances, and is a motor control for a digital disc player that can prevent malfunctions in the motor control operation for maintaining a constant linear velocity due to tracking of parts with no bits between tracks. The purpose is to provide equipment.

[Summary of the invention]

In this invention, when the playback output level of the disk is below a predetermined level, control of the rotational speed of the disk drive motor based on information indicating the linear velocity detected from the playback output of the disk is prohibited.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

The digital data signal SB read out by the pickup element 12 is sent to the signal processing circuit 13 as a high frequency signal SA.
given to. The input signal of the signal processing circuit 13 is level-sliced, for example, to obtain a digital data signal SI1. The maximum inversion interval detection circuit 14 uses the reference signal output from the reference signal generation circuit 15 to determine the inversion interval (from the rising edge to the falling edge, or vice versa, or vice versa) of the digital data signal S for a certain period of time. The distance between both reversals is measured, and the frequency component having the maximum reversal interval is detected according to the measurement result.The motor control circuit 16 is configured to detect the frequency component having the maximum reversal interval so that the reversal interval of the frequency component having the above-mentioned reversal interval is different from the predetermined interval. , controls the rotational speed of the disk drive shaft 17. As a result, the linear speed of the row of grooves on the disk 11 is kept constant.

The detection prohibition signal generation circuit 18 prohibits the detection operation of the maximum inversion interval detection circuit 14 if the signal level of the high frequency signal RF processed by the signal processing circuit 13 is less than a predetermined value. The detection level LD of the detection prohibition signal generation circuit 18 is shown in FIG. 2, and is set below the lower limit of the variable range of the slice level L in the reproduction signal processing circuit 13. In FIG. 2, the detection operation of the maximum inversion interval detection circuit 14 is prohibited while the detection inhibition signal Sc applied from the detection inhibition signal generation circuit 18 to the maximum inversion interval detection circuit 14 is at a high level. Thereby, even when tracking a portion where there is no row of gaps between tracks, it is possible to prevent the motor control operation for keeping the linear velocity constant from malfunctioning.

In addition, in this invention, the detection operation of the maximum/maximum inversion interval detection circuit 14 is continued, and the detection inhibition signal S is output. Of course, if the maximum inversion interval detection circuit 14 is at a high level, the detection output of the maximum inversion interval detection circuit 14 may not be applied to the motor control circuit 16. In short, when the reproduction output level of the disc 11 is low, the motor control operation of the motor control circuit 16 based on the detection output of the maximum reversal interval detection circuit 14 may be prohibited.

In addition, this invention is effective not only for tracking parts where there is no bit string between tracks, but also for scratches on the disc surface, which lowers the level of the high-frequency signal SA and causes the digital data signal SR to be obtained. It is also effective when there is a problem.

The present invention is also applicable to a system that controls the rotational speed of the motor 17 according to the detected output of the maximum cycle or minimum cycle of the data signal.

〔Effect of the invention〕

As described above, according to the present invention, the motor control operation based on the detection output of linear velocity information is prohibited during a period when the reproduction output level of the disc is low and the original digital data signal cannot be reproduced. Even when tracking a portion where there is no bit string, it is possible to prevent the motor control operation from significantly malfunctioning. .

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing the configuration of an embodiment of the present invention, and FIG.
The figure is a diagram for explaining the operation of FIG. 1, and FIG. 3 is a diagram for explaining the conventional problem. DESCRIPTION OF SYMBOLS 11... Disc, 12... Optical pickup element, 13... Signal processing circuit, 14... Maximum reversal interval detection circuit, 15... Reference signal generation circuit, 16... Motor control circuit, 17...Motor, 18...Detection prohibition signal generation circuit.

Claims (1)

[Scope of Claims] A digital disc player that reproduces digital data signals from a disc rotationally driven according to a constant linear velocity method, comprising: linear velocity information detection means for detecting information indicating linear velocity from the reproduction output of the disc; a motor control means for controlling the rotational speed of a motor that rotationally drives the disk according to a detection output of the linear velocity information detection means; and a detection output of the linear velocity information detection means when the level of the playback output of the disk is below a predetermined level. A motor control device for a digital disc player, comprising prohibition means for prohibiting a motor control operation of the motor control means.