JPH0820907B2 - Speed controller - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotation speed control device, and more particularly to a coarse and precise rotation speed control device for a recording medium.

2. Description of the Related Art In recent years, a video disc in which a video signal is FM-modulated and recorded on a disc-shaped recording medium is commercially available. For these reproductions, the coarse rotation speed control is first performed to rotate the recording medium at an appropriate rotation speed, and at the speed at which the signal can be demodulated, the signal is switched and the recording medium is rotated at a precise rotation speed based on the reproduced synchronizing signal. The rotation speed was controlled. A frequency generator (hereinafter referred to as FG) attached to a motor that rotates the recording medium has been used for rough rotation speed control.

An example of the above-described conventional rotation speed control device will be described below with reference to the drawings. FIG. 3 is a block diagram of a conventional rotation speed control device. In Figure 3
101 is FG, and its output is connected to the frequency / voltage converter 102, and the rotation speed is converted into voltage. Frequency / voltage converter 10
The output of 2 is compared with the reference voltage 104 by the subtracter 103, passes through the signal switch 105 and the amplifier 106, and the motor 107 is supplied with the reference voltage 104.
Rotate at a speed determined by. This is the rough rotation speed control loop.

On the other hand, a pickup 108 that reproduces a signal from a recording medium.
Is demodulated by the demodulator 109 and the synchronization signal extractor 110 of the next stage is demodulated.
The sync signal is extracted at. This signal is phase-compared by the phase comparator 111 with the output signal of the reference signal generator 112. The output of the phase comparator 105 is connected to the other input terminal of the signal switch 105. The output of FG101 is also connected to the rotation speed detector 113, and when the sync signal extractor 110 reaches the speed at which the sync signal can be extracted, the signal of the signal switch 105 is switched to the phase comparator 111.
The output signal of the motor passes through the signal switcher 105 and the amplifier 106.
Control 107. This is a loop for precise rotation speed control.
A microcomputer is often used to determine the rotation speed of the rotation speed detector 113.

Problems to be Solved by the Invention However, the motor for rotating the recording medium as described above requires an FG, which causes a cost increase.

In view of the above problems, the present invention provides a rotation speed control device that does not require an FG.

Means for Solving the Problems In order to solve the above problems, the rotation speed control device of the present invention uses a signal reproducing means for reproducing a signal from a recording medium recorded with a binary signal, and the reproduced signal frequency. Frequency / voltage converting means for converting to voltage, first signal selecting means for selecting an output of the frequency / voltage converting means and an output of a first voltage generator for generating a predetermined voltage, and the first signal The subtraction means subtracts the output of the selection means and the output of the second voltage generator for generating a predetermined voltage, the amplitude discrimination means for discriminating the amplitude of the output signal of the signal reproduction means, and the output of the amplitude discrimination means. First for switching control of the first signal selecting means
Signal selector control means, signal demodulating means for demodulating the output signal of the signal reproducing means, synchronizing signal extracting means for extracting a synchronizing signal from the output signal of the demodulating means, and output signal of the synchronizing signal extracting means. Phase comparing means for phase comparing an output signal of a reference signal generator for generating a predetermined frequency signal, second signal selecting means for selecting an output signal of the subtracting means and an output signal of the phase comparing means, A sync signal detecting means for detecting that the signal extracting means has extracted a sync signal; and a second signal selector controlling means for switching and controlling the second signal selecting means by the output of the sync signal detecting means. Recording medium rotation driving means for amplifying the output of the second signal selector control means and rotating the recording medium.

As the recording medium, a disk-shaped recording medium having a concave-convex shape or magnetically recorded with a binary signal is used. As the frequency / voltage converting means, one using a monostable multivibrator or another general one is used. As the signal selection means, a mechanical relay or an electronic switch using CMOS is used. An operational amplifier or the like is used as the subtraction means. A comparator is used as the amplitude discriminating means. As the signal demodulating means, an FM demodulator or a digital signal demodulator for demodulating a modulated digital signal is used depending on the format recorded on the recording medium. The synchronizing signal extracting means also uses a horizontal synchronizing signal separator or a frame synchronizing signal separator for extracting a frame that divides a unit of a digital signal, depending on the recorded signal. An ordinary phase comparator is used as the phase comparison means.

Action The present invention has the above-mentioned configuration and is used for detecting the speed of the motor that rotates the recording medium. Frequency generator (FG)
Is unnecessary and speed information can be obtained from the disk, so that more accurate rough rotation speed control can be performed.

Embodiment A rotation speed control device according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing an embodiment of the present invention. In FIG. 1, reference numeral 1 is a pickup as a means for reproducing a signal from a recording medium, and its output is subjected to waveform shaping by a comparator 2 and then converted into a voltage by a frequency / voltage converter. That is, the output voltage of the frequency / voltage converter 3 is proportional to the rotation speed of the recording medium. Generally, when considering the output of the pickup 1 including its buffer amplifier, the frequency characteristic in the high frequency range is extremely deteriorated. Further, in the differential type magnetic head type pickup, the low-frequency amplitude is deteriorated. In these cases, the waveform shaping by the comparator 2 is not performed accurately, and the rotation speed information cannot be obtained accurately, so the motor may run away. Therefore, when the output signal of the pickup 1 is connected to the amplitude discriminator 4 and the recording medium rotates at high speed,
The first signal switch 5 is controlled. When the amplitude discriminator 4 is provided with a low-frequency signal cutoff characteristic, it is possible to detect even when the rotation speed of the recording medium is low. With this configuration, when the rotation speed of the recording medium is slow, the first signal switch 5 is switched to the first voltage generator 6 and the subtractor 7 outputs the second voltage generator 8 and this signal. The second signal switcher 9 and the amplifier 10 which are subtracted and compared
The motor 11 is controlled via. In other words, the initial rotation is the first
The motor (recording medium) rotates at the number of rotations determined by the voltage of the voltage generator 6. When the recording medium reaches a substantially predetermined number of revolutions, the pickup output signal is judged by the amplitude discriminator and the first signal switch is switched to the frequency / voltage converter 3 side. As a result, the motor 11 can be controlled by looking at the signal of the recording medium.
Such control is important when the number of revolutions is not constant as in the case of constant linear velocity recording.

If rough rotation speed control can be achieved by the above control, signal demodulation is possible. The output signal of the pickup 1 is also connected to the demodulator 12 where it is FM demodulated. The output of the demodulator 12 is connected to the sync signal extractor 13 where the horizontal sync signal is extracted. The horizontal synchronizing signal and the output signal of the reference signal generator 14 are phase-compared by the phase comparator 15, and this output is connected to the other input of the second signal switch 9. The output of the sync signal extractor 13 is connected to the sync signal detector 16 to determine whether or not the sync signal can be accurately extracted. FIG. 2 shows an embodiment of the synchronizing signal detector 16, and the parts corresponding to those in FIG. 1 are designated by the same numbers. In FIG. 2, the output of the sync signal extractor 13 is a phase locked loop (PLL) 2
Connected to 1. When the PLL is not pulled in, the error signal output is random and has a large amplitude, and when pulled in, the error signal becomes small. The error signal of this PLL is connected to the amplitude discriminator 22. This amplitude discriminator is preferably an absolute value detection type such as a find comparator.

When the sync signal detector 16 finds that the sync signal has been detected, the output signal controls the second signal switch 9 to switch to the output signal side of the phase comparator 15. Therefore, the motor 11 is phase-locked to the synchronizing signal extracted from the recording medium, and accurate rotation speed control is performed.

As described above, in the present invention, the coarse rotation number control of the recording medium is controlled so that the average edge number of the binary signal reproduced from the recording medium becomes constant, so that the FG which was conventionally required is not necessary. Become. In the case of an optical pickup, if the focus is not applied and the signal is not reproduced, the motor may run out of control, but if such a danger is detected by the amplitude discriminator and the amplitude of the playback signal decreases, This danger is eliminated by controlling the motor to rotate at a predetermined speed.

Further, the switching from the rough rotation speed control to the precise rotation speed control is also performed after confirming that the synchronization signal is detected, thereby realizing more accurate control.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of the present invention, FIG. 2 is a block diagram showing an example of a sync signal detector used in the embodiment shown in FIG. 1, and FIG. 3 is a conventional rotational speed. It is a block diagram showing an example of a control device. 1 ... Pickup, 3 ... Frequency / voltage converter, 4 ...
… Amplitude discriminator, 5,9 …… Signal changer, 6,8 …… Voltage generator, 11 …… Motor, 12 …… Demodulator, 13 …… Synchronous signal extractor, 14 …… Reference signal generator, 15 …… Phase comparator, 16 ……
Sync signal detector.

Claims (1)

[Claims] 1. A signal reproducing means for reproducing a signal from a recording medium recorded with a binary signal, a frequency / voltage converting means for converting the reproduced signal frequency into a voltage, and the frequency / voltage converting means.
First signal selecting means for selecting an output of the voltage converting means and an output of a first voltage generator for generating a predetermined voltage, and second output for outputting the output of the first signal selecting means and a predetermined voltage. A subtracting means for subtracting the output of the voltage generator, an amplitude discriminating means for discriminating the amplitude of the output signal of the signal reproducing means, and a first for controlling the switching of the first signal selecting means by the output of the amplitude discriminating means. Signal selector control means, signal demodulating means for demodulating the output signal of the signal reproducing means, and synchronizing signal extracting means for extracting a synchronizing signal from the output signal of the demodulating means,
Phase comparing means for phase comparing the output signal of the synchronizing signal extracting means and the output signal of the reference signal generator for generating a predetermined frequency signal, and the output signal of the subtracting means and the output signal of the phase comparing means are selected. A second signal selecting means, a synchronizing signal detecting means for detecting that the synchronizing signal extracting means has extracted a synchronizing signal, and a switching control of the second signal selecting means by an output of the synchronizing signal detecting means. 2. A rotation speed control device comprising: two signal selector control means; and a recording medium rotation driving means for amplifying an output of the second signal selector control means and rotating the recording medium.