JPS58154381A - Rotating speed controller for disc reproducer - Google Patents

Abstract

PURPOSE:To effectively reproduce a normal information signal by controlling the rotating speed of a disc to normally operate a PLL circuit. CONSTITUTION:A motor 12 rorates a disc 10. A servo system has a tachometer generator 20, a F/V converter 22 and an amplifier 24. In order to confirm whether a PLL circuit 16 normally operates or not, a PLL lock detector 26 is provided. The detection signal of the detector 26 is inputted to a discriminator 28. The output of the discriminator 28 is inputted through an amplifier modulator 36 to an adder 38, thereby controlling the motor 12 to drive the disc 10 to always normally operate the PLL circuit 16.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a disk rotation speed control device in a disk reproducing apparatus that reproduces a disk (disc-shaped record carrier) on which signals are recorded in a spiral or concentric pattern.

The conventional general configuration of this disc playback device is the first one.
Shown in the figure. The disk 10 is rotationally driven by a motor 12, and the signals recorded on this disk 10 are received by a signal detection section 14 including a pickup. A PLL (phase locked loop) circuit 16 is a signal detection section 14
The reproduced clock signal B is extracted from the first h raw No. 16 A obtained as the output of the . The signal demodulation circuit 18 demodulates the reproduced signal A using the reproduced clock signal B as a synchronization signal, and outputs the demodulated information signal C.

Further, the device for controlling the rotational speed of the disk 100 is configured, for example, by an Are (automatic frequency control) serze thread as shown. In other words, the motor 12 is connected to (b) a tacho generator 20 for detecting rolling speed, and its output signal is input to the F/V converter 22, which
The /V controller 22 outputs a voltage signal corresponding to the rotational speed of the motor 12.Then, the output signal of the F/V controller 22 is amplified by the amplifier 24. The motor 12 is rotationally driven by the output.

This constitutes an AFc servo I system that operates to maintain the rotational speed of the motor 12 at a predetermined value.

In the above configuration, when the AFO serase system is activated, the rotation speed of the motor 1o gradually increases and finally reaches a constant rotation. If the rotational speed of the disk IO at this time is normal and the frequency of the clock signal included in the reproduction signal AK is within the capture range of the PLL circuit 16, the PLL circuit 16
The circuit 16 starts operating normally, and a regular information signal C is obtained from the signal demodulation circuit 18.

However, in the conventional rotational speed control device described above, the above-mentioned A
If temperature drift or the like occurs in the FO servo system and the steady rotational speed of the disk 10 goes out of order, and as a result, the frequency of the clock signal included in the reproduced signal A deviates from the capture range of the PLL circuit 16, the PLL circuit 16 will remain It will not operate normally, and therefore a regular information signal C will not be obtained.

A similar abnormal condition is 1. Drift also occurs in the FLL circuit 16 when the clock frequency included in the reproduced signal is relatively out of the capture range of the PLLIa path 16.

This invention was made in view of the conventional problems mentioned in i. An object of the present invention is to provide a rotational speed control device for a disk reproducing device which adjusts the input Ml number to fall within the capture range and ensures that a regular information signal is obtained.

In order to achieve the above object, the present invention provides a PLL lock detector that detects that the clock signal frequency included in the reproduced signal is within the capture range of the PLL circuit and that the PLL circuit is operating normally. And this PL
If no detection signal is obtained from the L lock detector ('', then the L' hair A/ is increased until the detection signal is output).
A gradual increase signal generation circuit is provided which generates a multiplication signal and applies it to a servo control system that drives the disk synchronously, and changes the rotational speed of the disk so that the input of the PLL circuit falls within its capture range. shall be.

Hereinafter, preferred embodiments of the present invention will be described based on the drawings.

FIG. 2 shows the configuration of a disc playback device to which the present invention is applied, and FIG. 3 shows its operating waveforms. The basic configuration of the AFO selection system consisting of the motor 12 that rotates the disk 10, the tacho generator 22, the F/V controller 22, and the amplifier 24 is the same as that of the conventional device shown in FIG. 1, but in the present invention, , the output signal of the F/■ converter 22 is input to the amplifier 24 via the adder circuit 38. Further, the signal detection section 14, PLL circuit 16, and signal demodulation circuit 18 are the same as those in the conventional device shown in FIG.

In the apparatus of this invention, a PLL lock detection circuit 26 is provided to check whether the PLL circuit 16 is operating normally. This PLL lock detection circuit 2
The output signal E of 6 becomes high level when the PLL circuit 16 operates normally. This detection signal E is applied to one input side of the discrimination circuit 28.

The above A that drives the AFO open/open field detector 3o motor 12
FC? The -Jff system detects whether or not there is a peak in operation, and its output signal E is at a high level when the SURZE system is in operation. This output signal is delayed by one fixed time Td in the delay circuit 32 and applied to the other input side of the discrimination circuit 28. The discrimination circuit 28 is a logic gate operated by two people, and the signal delayed from the signal 1 is at a high level (that is, Td time is shorter than the start-up of the AFO serase system), and the PLL lock detector 2
When the detection signal E of 6 is at a low level (the PLL circuit 16 is not operating normally), the output signal F of the discrimination circuit 28 is still at a low level. This relationship is shown in FIG.

When the output signal F of the discrimination circuit 28 becomes high level, the oscillator 34 and the amplitude modulation circuit 36 are activated. When the oscillator 34 starts operating, an alternating current signal G having a constant frequency and a constant amplitude is output as shown in FIG. 3G. The amplitude modulation circuit 36 is
A vibration modulation is applied to the alternating current signal G that is input from the start-up time to gradually increase its amplitude from zero over time, and an amplitude-modulated gradually increasing signal H (shown in FIG. 3 H) is output. . This gradual increase signal H is input to the adder circuit 38, added as an offset voltage to the output of the F/V converter 22, and becomes an input to the amplifier 24, thereby changing the rotational speed of the motor 12.

In the above configuration, for example, an AFO sensor? Drift, etc. has occurred in the system, and as shown in Figure 3, the start-up ff
Even if 1Ta time is exceeded, the disk 100 rotation speed is PL.
If it does not fall within the capture range of the L circuit 16, an oscillating voltage H whose amplitude gradually increases is generated from the amplitude modulation circuit 36,
This is applied to the AFO sensor i system as an offset voltage. As a result, the rotational speed of the disk 10 also varies according to the vibration voltage H, and the range of variation gradually increases. As a result, when the rotational speed of the disk 100 falls within the capture range of the PLL circuit 16, the PLL circuit 16 starts normal operation. When this PLL circuit 16 starts normal operation, the output E of the PLL lock detector 26 becomes a low level.
In response to this, the output F of the discrimination circuit 28 becomes a low level, and the operations of the oscillator 34 and the amplitude modulation circuit 36 are stopped. Thereafter, due to the normal operation of the PLL circuit 16, a regular information signal C is obtained from the signal demodulation circuit 18. K like this
Therefore, in the device of this investigation, AFO serase system and PLL circuit 1
6. Abnormalities due to drift etc. are compensated for.

In the above embodiment, an oscillating current with a gradually increasing signal H is used, but if drift in only one direction is a problem, a DC signal with an increasing level may be used.

Furthermore, instead of adding the gradual increase signal H to the output of the F/V converter 22, the gain of the servo control system such as the amplifier 24 may be changed using the gradual increase signal H, and the same effect as described above can be obtained. is obtained. Furthermore, although the above embodiment employs an AFO servo control system for controlling the rotational speed of the disk, the present invention is also effective even if the servo control system is another system such as an APO system. It goes without saying that the signal demodulation circuit 18 may be any oI'#I4 circuit for digital signals or analog signals.

As described above in detail, according to the rotational speed control device for a disk playback device according to the present invention, the rotational speed of the disk is controlled so that the PLL circuit operates normally even if temperature drift or load fluctuation occurs. , it is possible to reliably reproduce a regular information signal.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a conventional disc playback device, FIG. 2 is a block diagram of a disc playback device to which a rotational speed control device according to an embodiment of the present invention is applied, and FIG. 3 is an operation of each part of the device shown in FIG. FIG. 3 is a timing chart diagram showing waveforms. Identical members in each figure are given the same reference numerals, lO is a disk,
12 is a motor, 14 is a signal detection section, 16 is a PLL (b)
18 is a signal demodulation circuit, 2o is a tacho generator, 2
6 is a PLL lock detection circuit, 36 is an amplitude modulation circuit, 38
is an adder circuit, and H is a gradual increase signal. Agent Patent attorney Kuzu, Shin Nobu - (1 other person) Figure 1 r mL , -,
,,,,---,,-,,-,--,,-j '3rd
Figure piece length, indication of 'i-0' Name of Japanese Patent Application No. 57-034965 No. 1 Rotational speed melon control in disk reproducing device

Claims (1)

[Claims] (A1 immersion detection unit for reading signals from a disk driven 11 times; and a PLII circuit for extracting a reproduced clock signal from the reproduced signal read by the signal detection unit; In a disc playback device comprising a signal@I modulation circuit that demodulates the playback signal and a servo control system that controls the rotational speed of the disc, the clock signal frequency included in the playback signal is within the capture range of the PLL circuit. a PLL lock detector that detects that the PLL1 path is operating normally; and a gradual increase signal that gradually increases the level until the detection signal is output when a detection signal is not obtained from the PLL lock detector. and a gradual increase signal generation circuit for generating a signal and applying it to the servo control system, and changing the rotational speed of the disk so that the input of the PLL circuit falls within its capture range. Rotational speed control device. (2. The device according to claim (1), wherein the gradually increasing signal generating circuit outputs an oscillating voltage whose amplitude gradually increases. (3) Scope of Claims (1) The disc is characterized in that, in the apparatus according to (2), the output signal of the j path to the gradual increase signal generation is applied as an offset voltage to the servo control system. A rotational speed control device in a reproduction device. (4) In the device according to claim (1) or (2), an output signal of the gradual increase signal generation circuit is applied as a gain control voltage to an amplifier of the servo control system. A rotation speed control device for a disc playback device that is characterized by: