JPH01298573A - Optical disk reproducing device - Google Patents

Abstract

PURPOSE:To simplify the constitution of the title device, to reduce cost of parts and to easily miniaturize the device by providing the device with a frequency dividing means for dividing the frequency of a reproducing bit signal in a video area at a prescribed frequency dividing ratio, and at the time of abnormal reproducing in the video area, applying the output of the frequency dividing means to an abnormal rotation control means to control the rotation of a disk. CONSTITUTION:A bit signal is formed from an RF signal by a waveform shaping circuit 54 and inputted to a frequency divider 56 to divide the frequency of the input signal into 1/40. The frequency-divided output is inputted to a CD signal processing circuit 38A through a change-over switch 50, an error signal indicating the slow rotation of the disk 10 is continued to be outputted for a while, the signal is integrated by an operational amplifier 52, and when voltage impressed to a disk motor 32 is boosted and the maximum pulse width in the frequency-divided signal is finally reached to a fixed value, a rough servo lock detecting signal is outputted and stabilized. Thus, the device can be miniaturized.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an optical disc playback device, and particularly relates to a video area in which an FM modulated video signal is recorded together with a digital audio signal on an LD or CDV, and a video area on a CD, CDV, etc. The present invention relates to an optical disc reproducing device capable of reproducing both an audio area in which only digital audio signals are recorded.

[Conventional technology]

For example, when playing back the video area of a CDV disc with a player capable of playing CDV, the rotation of the disc motor is controlled by the disc motor rotation control system shown in FIG.

When the disk IO is in a normal reproduction rotation state, rotation control is performed based on the horizontal synchronization signal in the reproduced video signal.

That is, the optical detection signal of the optical pickup 12 is amplified by the amplifier 14, and after the RF multiplied signal is detected, the FM modulated video signal is extracted by the band pass filter 16.

Next, a demodulator 18 demodulates the composite video signal, and a horizontal synchronization detection circuit 20 detects a horizontal synchronization signal from this composite video signal.

The phase of the horizontal synchronizing signal is compared with the reference signal from the reference signal generator 24 by the phase comparator 22, and the phase difference pulse (error signal) is integrated by the LPF 26. After 2 days, the changeover switch is switched to the L side. amplified by an amplifier 30,
The signal is output to the disk motor 32 and driven.

As a result, the disk 10 rotates so that the frequency of the horizontal synchronizing signal in the composite video signal exactly matches the specified value, and image reproduction becomes possible.

At this time, digital audio signal components are extracted from the RF multiplied signal by the LPF 34, waveform-shaped by the waveform shaping circuit 36, and then input to the CD signal processing circuit 38, where audio sample data is read.

On the other hand, if the disk has just started up from a stopped state and has not yet reached a sufficient rotational speed, or if the disk has run out of control and reaches an abnormally high rotational speed, the horizontal synchronization signal is cannot be detected normally, and the rotation control described above does not work properly.

Therefore, during abnormal playback when the rotational speed of the disk 10 deviates significantly from the value during normal playback, the disk motor 3
The rotation speed of 2 itself is directly detected, and the rotation is controlled so that this becomes a predetermined value.

For example, a frequency generator 40 attached to the disk motor 32
The FC signal of The signal is output to the amplifier 30 via the changeover switch 2, which is switched to the U side before the start-up or when runaway is detected.

As a result, when the disc motor 32 is started, it is controlled to a predetermined rotational speed as a target, and when the disc motor 32 runs out of control, it is controlled to return to the predetermined rotational speed.

When the specified rotation speed is reached and the horizontal synchronization signal is detected,
By switching the changeover switch 28 to the L side, it is possible to shift to the above-described accurate disk rotation control.

[Problem to be solved by the invention]

However, with such conventional technology, in order to control the disk motor rotation during abnormal playback in the video area,
It is necessary to install a frequency generator and a motor back electromotive force detector for detecting the rotation speed in the disk motor, as well as a frequency/voltage conversion circuit, etc., which complicates the configuration, increases component costs, and reduces the size of the device. The problem was that it was difficult to convert.

The present invention has been made in view of the problems of the prior art described above, and an object thereof is to provide an optical disk reproducing device that has a simple configuration, reduces component costs, and is easy to downsize.

[Means to solve the problem]

In this invention, an audio area where a digital audio signal is recorded and a video area where an FM modulated video signal is recorded are played back, and when abnormal playback occurs in the audio area, a playback bit signal is input and a predetermined part of the audio area is played back. An optical disc playback device having an abnormal rotation control means for controlling the disc rotation so that the pulse length is constant, comprising a frequency dividing means for frequency dividing a reproduced pit signal in a video area at a predetermined frequency division ratio, The present invention is characterized in that during abnormal playback in the video area, the output of the frequency dividing means is given to the abnormal rotation control means to control the disk rotation.

〔Example〕

One embodiment of the invention will be described with reference to FIG.

1 shows a block diagram of a disc motor rotation control system of an optical disc reproducing apparatus according to the present invention.

The disk 10 is set on a table connected to the rotating shaft of the disk motor 32 and is driven to rotate.

The signal recorded on the disk 10 is detected by an optical pickup 12 and output as a photodetection signal.

An amplifier 14 is connected to the output side of the optical pinkup 12, and amplifies the photodetection signal and outputs an RF multiplied signal.

The output side of the amplifier 14 is divided into a plurality of systems, one of which is connected to a video system band pass filter I6, from which an FM modulated video signal is extracted from the RF multiplied signal.

A demodulator 18 is connected to the output side of the bandpass filter 16, and a composite video signal is demodulated from the FM modulated video signal.

A horizontal synchronization detection circuit 20 is connected to the output side of the demodulator 18, and separates the horizontal synchronization signal from the composite video signal.

A phase comparator 22 is connected to the output side of the horizontal synchronization detection circuit 20, and a phase comparison is made between the reference signal (15,734KHz) inputted from the reference signal generator 24 and the horizontal synchronization signal, and the phase difference is calculated. A pulse (error signal) is output.

The output side of this phase comparator 22 is connected to an LPF 26 to integrate the error signal.

The output side of the LPF 26 is connected to the input terminal side of the changeover switch 28.

An amplifier 30 is connected to the output terminal S of the changeover switch 28, and the switch is set to ■, during normal playback in the video area.
The error signal after integration is amplified by the LPF 26 and output to the disk motor 32.

This allows disk rotation control during normal playback.

The output side of the amplifier 14 is also connected to an audio system.

The output side of the amplifier 14 is connected to the input terminal A of the changeover switch 48.
(audio) side and LPF3
4 to the input terminal (video) side of the selector switch 48.

An output terminal C of the changeover switch 48 is connected to the waveform shaping circuit 36.

Here, the changeover switch 48 is switched to the A side when reproducing the audio area of the CD or CDV, and the RF multiplied signal is inputted as is to the waveform shaping circuit 36, and the EFM signal is restored.

Conversely, when reproducing the video area of LD or CDV, the selector switch 48 is switched to the V side, and the RF multiplied signal is
After the digital audio signal portion is extracted in step 34, the EFM signal is restored by waveform shaping.

This EFM signal corresponds to a pit signal in the audio area of a CD or CDV, but corresponds to the duty ratio of a focus signal in the video area of an LD or CDV.

The output side of the waveform shaping circuit 36 is connected to the input terminal P side of a changeover switch 50, and the output terminal R of this changeover switch 50 is connected to the CD signal processing circuit 38A.

When the optical pickup 12 is in the audio area and during normal playback in the video area, the selector switch 50 is switched to the P side, and the CD signal processing circuit 38A is switched to the P side during normal playback.
Audio sample data is then reproduced from the FM signal.

This audio sample data is processed by the CD signal processing circuit 38.
D/A converter (not shown) connected to the output side of A
etc. is output to.

This CD signal processing circuit 38A also has a function of forming an error signal for disk motor control from the input signal, and this error signal is output to the operational amplifier 52 connected to the output side and integrated.

The output side of the operational amplifier 52 is connected to the input terminal U side of the changeover switch 28, and the switch is switched to the U side except during normal playback in the video area, and the disc is switched to the U side based on the error signal of the CD signal processing circuit 38A. The rotation of the motor 32 is controlled.

Here, to explain how the error signal is formed by the CD signal processing circuit 38A, during normal playback of the audio area, the selector switch 4 is switched to the A side and the selector switch 50 is switched to the A side.
The PLL clock extraction circuit extracts a clock from the EFM signal input by switching to the P side of is output as a regular servo error signal.

For accurate playback according to the CD format, EFM
The clock frequency of the signal is 4.3218 MHz.

In addition, when the PLL clock extraction circuit is unlocked due to rotation start, track jump, etc., or during abnormal playback such as during high-speed search, the maximum pulse width pulse in the input signal (when inputting an EFM signal) detects the frame sync pulse) and calculates the frame sync pulse width (approximately 2.545
μS) is output as an error signal for rough servo.

As the CD signal processing circuit 38A having such a function,
For example, there is the Sony CX23036 which is an LSI for CD.
Just set it to L sea H mode.

However, the disk motor rotation control based on the error signal from the CD signal processing circuit 38A aims to set the clock frequency of the reproduced EFM signal to 4.3218 MHz when the input signal is an FM signal related to a digital audio signal. It is done as.

The CD signal processing circuit 38A also has a function of detecting the lock/unlock state of the PLL clock extraction circuit and outputting a detection signal, and a function of detecting lock/unlock of the rough servo and outputting a detection signal.

The output side of the amplifier 14 is also connected to a rough servo system in the video domain.

That is, the output side of the amplifier 14 is connected to the waveform shaping circuit 54, and the pit signal in the video area is restored.

The output side of this waveform shaping circuit 54 is connected to a frequency divider 56, and the frequency is divided by a ratio of 1/40, for example.

The output side of the frequency divider 56 is connected to the input terminal Q side of the changeover switch 50.

The selector switch 50 is switched to the Q side during abnormal playback in the video area (when the PLL clock extraction circuit is unlocked due to rotation start, track jump, etc., or during high-speed search), and the EFM signal is switched to the Q side. The output signal of the alternative frequency divider 56 is input to the CD signal processing circuit 38A.

Therefore, the CD signal processing circuit 38A outputs the above-mentioned error signal based on the frequency-divided output.

Next, the operation of the above embodiment will be explained.

First, there is an optical pickup 12 in the audio area of a CD or CDV, and when starting the disc 10 from a stopped state, the changeover switch 28 is set to the U side, and the changeover switch 48 is set to the A position.
side, the selector switch 5o is switched to the P side, and the CD signal processing circuit 38A is set to rough servo mode.

Note that switching and mode setting are performed by a system microcomputer (not shown).

Initially, when the disk IO is still stopped, the RF multiplied signal is not detected, so the rough servo error signal output by the CD signal processing circuit 38A is the maximum (indicating that the disk rotation speed is slow), and this is the result of the calculation. After being integrated by the amplifier 52, it is sent to the amplifier 30 via the changeover switch 28, where it is amplified and output to the disc motor 32 as a starting voltage.

This causes the disk 10 to start rotating.

As the disk IO rotates, the optical pickup 12 begins to detect an optical signal, which is amplified by the amplifier 14 and then converted into an RF multiplied signal, which is then input to the waveform shaping circuit 36 via the changeover switch 48.

The waveform shaping circuit 36 forms the RF multiplied signal and the FM signal, which is then passed through the selector switch 50 to the CD signal processing circuit 38A.
is input to.

The CD signal processing circuit 38A detects a pulse with the maximum pulse width from the input EFM signal, and compares it with 2.545 μs (hereinafter referred to as τ).

The maximum pulse width in the EFM signal is the frame sync pulse, but the frequency of the entire EFM signal is low immediately after the rotation of the disk 10 starts, so the pulse width is infinitely longer than τ.

Therefore, an error signal indicating that the rotation of the disk 10 is slow continues to be output for a while.

This error signal is integrated by LPF52, so LPF5
2's output increases, and the voltage applied to the disc motor 32 increases.

This accelerates the rotation of the disk 10.

As the rotation of the disk 10 becomes faster, the overall frequency of the reproduced EFM signal increases, and the pulse width of the frame sync pulse approaches τ.

Therefore, the error signal gradually becomes smaller, and the rise in the voltage applied to the disk motor 32 also becomes slower.

Finally, when the frame sync pulse width in the reproduced EFM signal matches τ, a rough servo lock detection signal is output.

When this lock signal is detected, the CD signal processing circuit 38A is set to the normal servo mode.

At this time, the PLL clock extraction circuit has begun to extract the clock, and after mode switching, the CD signal processing circuit 38A obtains an error signal from the clock extracted from the EFM signal and the reference signal, and outputs it to the operational amplifier 52.

Thereby, accurate rotational control of the disk motor 32 is performed.

At this time, the audio sample data is reproduced by demodulating the EFM signal and performing other signal processing, and is output to the outside.

When the PLL clock extraction circuit becomes unlocked due to a track jump or runaway rotation during normal playback of the audio area, it is energized by an unlock detection signal and set to the rough servo mode, and after the rough servo is locked. Returns to normal servo state.

Further, even during a high-speed search, the rough servo mode is set by being energized by a predetermined mode switching command.

Unlike this, when an optical pickup 12 is provided in the video area of the LD or CDV and the disc 10 is started from a stopped state, the changeover switch 28 is set to the U side, and the changeover switch 4
8 is switched to the V side, the changeover switch 50 is switched to the Q side, and
The CD signal processing circuit 38A is set to rough servo mode.

Initially, when the disk IO is still stopped, the RF multiplied signal is not detected, so a large error signal for rough servo is output from the CD signal processing circuit 38A, which is integrated by the operational amplifier 52 and then sent to the amplifier 30 via the changeover switch 28. The voltage is amplified and outputted to the disk motor 32 as a starting voltage.

This causes the disk IO to start rotating.

As the disk 10 rotates, the optical pickup 12 begins to detect an optical signal, which is amplified by the amplifier 14 and input into the waveform shaping circuit 54 as an RF multiplied signal.

This waveform shaping circuit 54 forms a pit signal from the RF multiplied signal, which is further input to a frequency divider 56 and frequency-divided by 1/40.

Here, the bit signal corresponds to an FM modulated video signal,
When played back at the normal rotation speed, in the NTSC system, the tip of the sync tip is 7.6 MHz and the white beak is 9.
It is 3MHz.

In terms of period, it is approximately 131.6 ns to 107.5 n
s, and the pulse width after dividing by 1/40 is approximately 2
．． It becomes 63 μs to 2.15 μs/S.

The frequency-divided output is input to the CD signal processing circuit 38A via the changeover switch 50.

The CD signal processing circuit 38A detects a pulse with the maximum pulse width from the input frequency-divided signal, and compares it with τ.

The maximum pulse width in the frequency-divided signal is due to the sync tip portion, but the frequency of the entire frequency-divided signal is low immediately after the rotation of the disk 10 starts, so the pulse width is slightly longer than τ.

Therefore, an error signal indicating that the rotation of the disk 10 is slow continues to be output for a while.

Since this error signal is integrated by the operational amplifier 52, the output of the operational amplifier 52 increases, and the voltage applied to the disk motor 32 increases.

This accelerates the rotation of the disk IO.

As the rotation of the disk IO becomes faster, the overall frequency of the frequency-divided signal increases, and the maximum pulse width related to the sync tip portion approaches τ.

Therefore, the error signal gradually becomes smaller, and the rise in the voltage applied to the disk motor 32 also becomes slower.

Finally, when the maximum pulse width in the frequency-divided signal matches τ, a rough servo lock detection signal is output.

When this lock signal is detected, the CD signal processing circuit 38A is set to the normal servo mode, and the selector switch 28 is switched to the P side and the selector switch 50 is switched to the P side.

When the maximum pulse width in the frequency-divided signal matches τ, the instantaneous frequency at the sync chip of the reproduced FM modulated video signal is approximately 7.85 MHz, which is slightly higher than the normal frequency, but it is sufficient for the demodulator 18 etc. to operate. frequency is sufficient for

Therefore, at this time, the bandpass filter 1 has already received the RF multiplied signal.
An FM modulated video signal is extracted at 6, and a composite video signal is demodulated at a demodulator 18.

Furthermore, a horizontal synchronization signal is separated from the composite video signal by a horizontal synchronization detection circuit 20, and a phase comparator 22 compares the phase with a reference signal to output an error signal.

Therefore, after mode switching, accurate rotational control of the disk motor 32 is performed using an error signal based on the horizontal synchronization signal.

At this time, a digital audio signal component is extracted from the RF multiplied signal by the LPF 34, and an EFM signal is further formed by the waveform shaping circuit 36 and input to the CD signal processing circuit 38A.

Therefore, after the mode is switched, the audio sample data is reproduced by the CD signal processing circuit 38A and output to the outside.

When the PLL clock extraction circuit becomes unlocked due to a track jump or runaway rotation during normal playback in the video area, the rough servo mode is set by being energized by an unlock detection signal.

At this time, the selector switch 28 is switched to the U side, and the selector switch 50 is switched to the Q side.

After the rough servo is locked, it is returned to the normal servo state.

Further, even during a high-speed search, the rough servo mode is set by being energized by a predetermined mode switching command.

According to this embodiment, during abnormal playback in the video area of an LD or CDV, the pit signal obtained by waveform shaping in the RF double signal waveform shaping circuit 54 is divided by the frequency divider 56 at a predetermined frequency division ratio. By inputting the rotating CD signal into the CD signal processing circuit 38A, and causing the CD signal processing circuit 38A to form an error signal for rough servo to control the rotation of the disc motor 32,
It is not necessary to provide a frequency generator or a motor back electromotive force detector in the disk motor 32 itself, and a frequency/voltage conversion circuit, etc., and it is possible to perform abnormal playback in the video area by adding a relatively simple circuit. It is possible to control the rotation of the disk motor in the system, thereby reducing costs and downsizing the device.

In the above embodiment, the frequency division ratio of the frequency divider was set to 1/40, but this is just an example, and in the case of the NTSC system, it is
It is sufficient to set it in the range of /35 to l/45, and
I/30 to I/4 for PAL optical disc playback devices
It may be set to about 0.

Further, rough servo is performed by detecting a pulse with the maximum pulse width among the input signals of the CD signal processing circuit 38A, but it may be performed by detecting a pulse with the minimum pulse width.

〔Effect of the invention〕

According to the optical disc playback device according to the present invention, the frequency division means divides the reproduction bit signal of the video area at a predetermined frequency division ratio, and the output of the frequency division means is disabled during unsteady rotation in the video area. By controlling the rotation of the disk by applying it to the rotation control means during steady state, there is no need to provide a rotation speed detector in the disk motor itself and a frequency/voltage converter, etc., resulting in a relatively simple circuit. In addition, it is possible to control the rotation of the disk motor during abnormal playback in the video area, resulting in excellent effects such as cost reduction and miniaturization of the device.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an optical disc reproducing apparatus according to one embodiment of the present invention, and FIG. 2 is a block diagram of a conventional optical disc reproducing apparatus. 10: Disc, 12: Optical pickup, 32
: Disk motor, 38A: CD signal processing circuit, 54: Waveform shaping circuit, 56: Frequency divider.

Claims (1)

[Claims] It is possible to play back the audio area where digital audio signals are recorded and the video area where FM modulated video signals are recorded, and when abnormal playback occurs in the audio area, a playback pit signal is input into the audio area. In an optical disc playback device having abnormal rotation control means for controlling the disc rotation so that the length of a predetermined pulse is constant, the optical disc playback device includes a frequency division means for frequency-dividing a reproduction pit signal in a video area at a predetermined frequency division ratio. An optical disk playback device comprising: during abnormal playback in a video area, the output of the frequency dividing means is given to abnormal rotation control means to control disk rotation.