KR900003057B1 - Recording disk displayer - Google Patents

Abstract

The appts. commprises a memory for storing demodulated signals during reproduction or playback. The disc is rotated by a motor and the information sensed by a pickup and amplified by a high frequency amplifier. The amplified information is then passed to a digital demodulator, an analogue audio demodulator and a video demodulator. A beat signal generator produces a beat signal for reading synchronised with the reproduction signal which is supplied by the information recorded on the disc. The system has units to monitor the utilisation of the memory, producing a control signal from the information obtained, to prevent any overfilling of the memory.

Description

Recording Disc Information Replay Device

1 is a diagram showing a frequency spectrum of an RF signal obtained from a recording disc constructed by superposing and recording a signal obtained by frequency-modulating a video signal and an audio signal and a signal pulsed by PCM-modulating an analog signal, respectively.

2 is a block diagram showing one embodiment of a recording disc information reproducing apparatus according to the present invention;

3 is a block diagram showing a specific circuit configuration of the disc discrimination circuit in FIG.

4 is a block diagram showing a specific circuit configuration of the regeneration clock extraction circuit in FIG.

* Explanation of symbols for main parts of the drawings

1: Spindle motor for LD, LDD 2: Spindle motor for CD

5: recording disc 10: disc discrimination circuit

12: Pickup 14: Digital Information Demodulation Meter

15: analog audio demodulator 16: video demodulator

22: EFM demodulation circuit 23: Regeneration clock extraction circuit

25: memory controller 27, 66: voltage controlled oscillator

38, 42: FM demodulator 31, 37, 48, 49: phase comparator

44: dropout compensator 52, 53: equalizer amplifier

76L, 76R: Mode Switch

The present invention relates to a recording disc information reproducing apparatus, and more particularly, to a reproducing apparatus for reproducing recording information of a recording disc on which a digital signal is recorded.

As a recording disc on which digital signals are recorded, digital audio discs, so-called compact discs (hereinafter, abbreviated as "CD"), in which audio signals are recorded by being digitally modulated and pulse-degraded, are known. A video disc by a method of digitally recording an audio signal into a pulse train signal by digitalizing the FM signal using a predetermined digital modulation method (see Japanese Patent Application Laid-Open No. 58-45780) (hereinafter abbreviated as LDD). Is developed.

In this recording method, the audio signal is two-channel and the 2.3 MHz and 2.8 MHz audio carriers are FM-modulated by two audio channel signals, respectively.

The video signal is frequency-converted so that the sync tip is 7.6MHz, the pedestal level is 8.1MHz, and the white peak is 9.3MHz.

The audio signal is then digitalized by a modulation method such as PCM (Pulse Code Modulation) and converted into a pulse train signal.

This pulse train signal is a signal suitable for recording by the EFM (Eight to Forrteen Modulation) method, for example, and the frequency spectrum is the frequency component of the pulse train having a width of 3T to 11T.

Here, T denotes the bit period of the PCM signal, and 3T and pulses are about 720KHz, and the maximum width of 11T pulses is about 200KHz.

Such a pulse train signal is superimposed at a level of about 1/10 or less with respect to the video main carrier, slice-amplified near the zero pass point, and becomes a pulse width modulated signal to become a recording signal. According to the above recording method, the frequency spectrum of the RF (high frequency) signal obtained from the recording disk on which the video signal and the audio signal are recorded is as shown in FIG.

1, the component represented by A is digitally substituted audio signal component, the component represented by B is audio FM signal component, the component represented by C is color information component in video FM component, and component represented by D. It is a luminance information component in this video FM signal.

Since the dynamic range of the digitized audio signal can be about 90 dB or more, the sound quality can be remarkably improved compared to recording and reproducing the audio signal by the FM modulation method.

In the CD playback apparatus, however, the PCM digital signal demodulator is a recording clock synchronized with the playback clock signal by fixing the read clock and synchronizing the rotation with the recording disk. The information once recorded in the memory is synchronized with the read clock. By reading, the jitter which is a time-base variation component is removed.

On the other hand, when demodulating the digital signal extracted from the reproduction signal by the video reproducing apparatus in the reproduction of the LDD, the reproduction signal is already synchronized with the reference signal for the video synchronizer, and in the conventional CD reproducing apparatus, the PCM demodulation is performed. When data is read into the memory using a separate reference signal, the playback video signal and the reproduced demodulated audio signal are shifted in time due to a slight phase shift from the two reference signals.

When the read clock is faster than the write clock, the memory data is lost. On the contrary, the late clock is overflowed.

SUMMARY OF THE INVENTION The present invention has been made in view of the above, and provides a recording disc information reproducing apparatus which can always use a memory in a steady state and can reliably suppress jitter components included in a reproduced digital signal to obtain a jitter-free digital signal. It aims to do it.

The recording disc information reproducing apparatus according to the present invention includes a demodulation means for demodulating a reproduction digital signal, recording means for recording the demodulation output of the demodulation means in synchronization with a reproduction clock signal included in the reproduction digital signal, and this memory. Clock generating means for generating a read clock signal for reading the stored information from the memory; phase turning means for synchronizing the output of the clock generating means with the reproducing clock signal; and monitoring the usage of the memory in accordance with the usage. And monitoring means for generating an output, and control means for controlling the read clock signal and the frequency by the clock generating means in accordance with the output of the monitoring means.

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

2 is a block diagram showing an embodiment of a recording disc information reproducing apparatus according to the present invention.

Such a reproducing apparatus is a compatible player capable of reproducing a normal video disc (hereinafter abbreviated as LD) in which video signals and audio signals are frequency-modulated at the same time as CD and LDD, respectively.

As described above, the player has a rotational speed different from that of a video disc (LD, LDD) and a digital audio disc (CD, so that the LD, LDD rotation drive is driven by the spindle motor (1) and the spindle motor for CD rotation drive (2). Is equipped.

These spindle motors 1 and 2 are selected according to the type of disc to be reproduced and are switched by, for example, a switching mechanism 4 which uses the motor 3 as a drive source.

In order to detect the disc 5 to be reproduced and the disc size, for example, three detection sensors 6, 7, 8 are provided corresponding to the disc size in the disc radial direction.

The size of the disc is about 5 inches (12cm) in the case of CD, and there are two types of discs (8 inches and 12 inches) in the case of video discs (LD and LDD).

The three detection sensors 6, 7, 8 and the respective outputs are subjected to waveform shaping in the waveform shaping circuit 9 and then supplied to the disk discriminating circuit 10. FIG.

For example, an optical sensor is used as the detection sensor, but is not limited thereto.

In the disc discrimination circuit 10, the disc to be reproduced on the basis of the detection outputs of the detection sensors 6, 7, 8 is discriminated from any of three types of discs: CD, LDD and LD.

3 shows a specific circuit configuration of the disc discrimination circuit 10. As shown in FIG.

In the case of the CD, the disc size is determined to be the minimum (12 cm), the detection sensor (6, 8) through the detection sensor (6), the detection output and the inverter (79, 80) and the reverse output of the highest inner circumference The output of the AND gate circuit 78 having 3 as the inputs becomes CD discrimination information.

In other words, CD detection is made when the detection sensor 6 is on and the other detection sensors 7 and 8 are off.

In the case of a video disc, since the disc sizes are 8 inches and 12 inches, the detection output of the detection sensor 7 or 8 becomes the angle / input of the AND gate circuits 70 and 71 through the OR gate circuit 69. .

The frame synchronizing detection signal generated when the frame synchronizing signal is detected from the frame synchronizing detection circuit 21 to be described later becomes the type force of the AND gate circuit 71 and is inverted by the inverter 72 and the AND gate circuit ( 70) of the type force.

When the detection output of the detection sensor 7 or 8 occurs, the LDD discrimination information is output from the AND gate circuit 71 when the plain synchronization detection signal is input, and the AND gate circuit when this frame synchronization detection signal is not input. LD discrimination information is output from 70.

These discrimination information is used as an indicator 11 for indicating the type of disk and for switching signals of various switches described later for driving.

The pickup 12 for reading recording information from the disc 5 is carried by a slider base (not shown) which is freely moved in the radial direction of the disc 5, and the slider base is slider-mounted. Is driven by a drive mechanism (not shown) made of a rotor, a reduction gear, and the like.

The read information read out from the recording disc 5 by the pickup 12 is passed to the digital information demodulation system 14, the analog audio demodulation system 15 and the video demodulation system 16 via an RF amplifier (AMP) 13. Each is supplied.

The RF amplifier 13 has a wide band of about 5 KHz to 14 KHz, and enables the amplifier of the reproduction PCM audio signal, the reproduction FM audio signal, and the reproduction video signal by a single amplifier.

In the digital information demodulation system 14, a switching switch 17 for switching in response to the type of the playback disc is provided, and this switch 17 is used for the LDD based on the disc information and the disc discrimination circuit 10 described above. In the case of CD on a axis, it is changed to b axis.

In other words, the signal processing system of the reproduction digital signal is switched during LDD reproduction and CD reproduction.

At the time of CD playback, the reproduction RF output is PCM audio information, which is subjected to MTF (Modulation Transfer Function) compensation, which compensates particularly high frequencies among the frequency characteristics in the equalizer 18.

On the other hand, in the LDD, the PCM audio information included in the reproduced RF signal simultaneously with the FM audio information and the FM video information is extracted by the LPF (Low Pass Filter) 19 to be supplied to the de-emphasis circuit 20. Supplied.

For example, the PCM audio information is superimposed on the low frequency component of the FM video signal because the digital component superimposes the digital signal on the FM-modulated video signal as it is during the EFM signal or recording.

Therefore, during reproduction, the low frequency component emphasized during recording is reversed by the de-emphasis circuit 20 to compensate. As a result, the S / N of the digital signal can be improved for low frequency noise during recording and playback.

In addition, instead of switching the signal processing system using the switching switch 17, the same effect can be obtained by turning on / off the supply power to the circuit of the processing system for each signal.

Instead of switching the signal processing system using the switching switch 17, the same effect can be obtained by turning on / off the supply power to the circuit of each signal processing system.

The reproduction EFM signal passing through the switching switch 17 is supplied to the EFM demodulation circuit 22 through the frame synchronization detection circuit 21 and also to the reproduction clock extraction circuit 23, so that the reproduction clock extraction circuit 23 is provided. The EFM demodulation circuit 22 demodulates the PCM digital signal by the regeneration clock extracted in FIG.

The demodulation signal is recorded in the memory 24 such as RAM (Random Access Memory) under the control of the memory controller 25, but at this time, the memory controller 25 records the divided output by the divider 26 of the playback clock. Recording is performed in synchronization with the clock.

The reading of the stored information from the memory 24 is carried out in a read clock obtained by dividing the oscillating output of the VCO (voltage controlled oscillator) 27 by the divider 28 in a PLL (Phase Locked Loop) circuit. Motivated.

This PLL circuit has a phase comparator (P /) in which the above-described VCO 27 and the regeneration clock have a divider output by the divider 29 and a divider output by the divider 30 of the VCO 27 oscillation output as two inputs. C)) 31 switches LP33 for inputting the comparative output and switching switch 33 for supplying the output voltage and reference voltage V ref ₁ of the LPF 32 to the VCO 27 alternatively. It consists of).

In this PLL circuit, the switching switch 33 switches the output voltage of the LPF 32 on the a-axis during the LDD playback, and the b-axis on the CD playback, based on the above discriminant determination of the disc discrimination circuit 10. The reference voltage V ref ₁ is supplied to the VCO 27.

Accordingly, during the LDD playback, the read clock for reading the stored information from the memory 24 is phase synchronized with the playback clock by the PLL circuit. During CD playback, the loop switch 59 to be described later is turned on so that the output of the phase comparator 31 is turned on. By driving the CD rotation drive spindle motor 2 via the LPF 77, the phase of the regeneration clock is synchronized with the fixed clock obtained by the VCO 27 in which the bias is fixed.

The digital signal read in this way is converted into an analog audio signal by the D / A (digital / analog) converter 34 to be the left and right reproduction audio outputs through the LPFs 35L and 35R.

The use status in the memory 24 is always monitored by the memory controller 25, and when the memory 24 overflows from the controller 25 or becomes blank (no data), these states are displayed. Information to be displayed is supplied to the voltage generator 36. During LDD regeneration, the voltage generator 36 generates a positive control voltage when the memory 24 overflows in response to information indicating the usage of the memory 24 from the memory controller 25. In this case, a negative control voltage is generated respectively and superimposed on the output voltage of the LPF 32 to be supplied to the VCO 27 through the switching switch 33 to control the frequency of the read clock.

In this way, the amount of storage data in the memory 24 is always monitored, and when there is an oversupply in the capacity and processing capacity of the memory 24, a positive or negative control voltage is generated to request the PLL circuit to cope with the memory 24. You can keep it steady.

In the analog audio demodulator 15, the outputs of the BPFs (Bandpass Filters) 37L and 37R, which pass only 2.3 MHz and 2.8 MHz audio carrier components in the reproduced RF signal, are FM demodulated by the FM demodulators 38L and 38R. The left and right regeneration cucumbers are also output through the amperage circuits 39L and 39R.

In the video demodulation system 16, only the video information is extracted to the BPF & notch circuit 40 in the reproduction RF signal. In this BPF & notch circuit 40, the EFM component and the 2.3 MHz and 2.8 MHz audio carrier components included in the reproduced RF signal are actively removed during LDD reproduction.

This extraction information is supplied to the FM demodulator 42 via the limiter circuit 41 and subjected to FM demodulation. This demodulation output is supplied to the dropout compensator (DOC) 44 through the LPF 43, and the dropout compensation is performed by the compensator 44. The drop out compensator 44 includes, for example, an analog switch which is turned off by a detection output of a drop out sensor (DOS) 46 which detects a drop out based on a regenerative RF signal supplied through an HPF (high pass filter). It is comprised by the holder capacitor installed between this switch output stage and a reference potential point. Therefore, when a drop or an out occurs, the output level of the LPF 43 immediately before the drop out sensor 46 is generated is fed to the cutoff circuit, and drop out compensation is performed. The output of this drop out compensator 44 becomes a video output.

The output of the dropout compensator 44 is also supplied to the horizontal synchronous separation circuit 47 so that the horizontal synchronous signal is a separate output. The horizontal synchronization signal is supplied to the phase comparators 48 and 49 to detect a phase difference with the reference signal output from the reference signal generator 50. The output of the phase comparator 48 becomes one input of the adder 51, and the output of the phase comparator 49 is equalized through the equalizer amplifier 52. The output of the adder 51 is equalized by the equalizer amplifier 53 and the driver 54. The spindle motor 1 for the LDD and LD rotational drive is driven through This is the spindol servo. The output of the output of the equalizer amplifier 52 drives an actuator (not shown) incorporated in the pickup 12 through the loop switch 55, the switching switch 56, and the driver 57. By driving the actuator, the optical spot for information reading is knitted in the tangent direction of the recording track of the disc. This is the Tangelshal seobogye. The actuator may be a tangential miller which rotates the optical spot for reading information in the tangential direction of the recording track of the disc by rotating the actuator. The optical track for tangential reading of the disc is changed by displacing the lens in a direction perpendicular to the optical axis. It is also good to have a structure for knitting in the direction. The loop switch 55 is turned on in response to the spin lock signal output from the spindle lock detection circuit 58 when the lock of the spindle servometer is approximately completed.

In other words, at the start of regeneration, first, the spindol motor 1 is driven by the output of the phase comparator 48 to adjust the time axis (spindle servo), whereby When the lock is approximately completed, the loop switch 55 is turned on and the actuator is driven at the output of the phase comparator 49 to perform fine adjustment of the time axis (tangential servo). As a result, the residual jitter component which cannot be excluded by the spindol servometer can be improved in the tangental servometer. However, even in the tangent thermal oscillator, the jitter can be completely removed because the mechanical system such as the actuator driving mechanism cannot sufficiently follow the high frequency component of the residual jitter. In the aforementioned digital information demodulator 14, the cut-off frequency of the LPF 32 of the PLL circuit generating the read clock is set lower than the maximum frequency of the band of the tangential servo loop to set the high frequency component of the residual jitter. By blocking, the residual jitter component can be removed. More preferably, by setting the cut-off frequency of the LPF 32 to be lower than the disc's eccentric frequency (30 to 8 Hz in the case of the LDD), jitter due to the disc's eccentricity can be completely eliminated.

The same effect can be obtained when the spindol servo and the tangential sorrow are performed based on the horizontal synchronization signal, but based on the 3.58 MHz color carrier included in the reproduced FM video signal.

As described above, the spindle servo is performed on the basis of the output of the phase comparator 31 in the digital information demodulation system 14 described above in the case of the playback of the CDs and the playback of the CDs. That is, the output of the phase comparator 31 drives the spindle motor 2 for the CD rotation drive through the loop switch 59 and the driver 60 which are turned on at the time of CD reproduction. In the conventional CD playback, the tangential servo is not performed, but the spin-dol motor 2 cannot sufficiently follow the high frequency component of the output signal of the phase comparator 31, which is a time axis error signal. The high-frequency component of the time-base error signal extracted by the?) Is adopted as a servo, ie, a tangent servo, which drives the actuator in the pickup 12 via the switching switch 56 and the driver 57. The switching switch 56 is switched to the a-axis when the LDD and the CD are reproduced, and the b-axis when the CD is reproduced, based on the discriminant result of the disc discrimination circuit 10.

In addition, the tangent servo may be based on the division output of the reproduction clock extracted by the reproduction clock extraction circuit 23, but based on the division output of the frame synchronization signal detected by the frame synchronization detection circuit 21. Even if it is possible, the same effect is obtained because the synchronization signal and the playback clock are in synchronism.

The output of the spin-lock detection circuit 58 is inverted by the inverter 62, and becomes a single input of the OR gate circuit 63 as the spin-dol unlock signal indicating that the spin-dol servo system is not in the locked state.

As the OR gate circuit 63, the type access force is supplied with a random access information signal generated during random access commands such as scan, search and jump.

The LD gate information output from the disc discrimination circuit 10 is also output to the OR gate circuit 63 again.

The output of the OR gate circuit 63 is supplied to the regeneration clock extraction circuit 23 through the control command circuit 64.

A fourth circuit configuration of the reproduction clock extraction circuit 23 is shown in the fourth. In this figure, the phase difference with the oscillation output of the VCO (voltage controlled oscillator) 66 is detected in the regenerator EFM signal in the phase comparator 65, and the phase difference signal is obtained through the LPF 67 and the switching switch 68. 66). In the above, the PLL circuit which produces | generates a regeneration clock is comprised.

The switching switch 68 normally supplies the output of the LPF 67 to the VCO 66 on the a-axis, but when the command signal is output from the control command circuit 64 mentioned above, the change-over switch 68 responds to the command signal. The predetermined reference voltage Vref ₂ is supplied to 66 by switching to. In other words, when the spindol servo is not in the locked state or when the optical spot for reading information is operated by the track emergency by random access commands such as scan, search, and jump, the reference voltage Vref ₂ is applied to the VCO 66. By fixing the oscillation frequency to a value close to the regeneration clock frequency, it is possible to quickly lock the regeneration clock after the spindol servo is locked or after the random access command is released.

2, the left and right pair of output terminals 73L and 73R of the analog audio output system and the left and right pair of output terminals 74L and 74R of the digital audio output system are provided in the audio output unit. The audio output from the analog audio demodulator 14 is supplied to the output terminals 73L and 73R. This audio output is also supplied to the output terminals 74L and 74R through the switching switch 75 during LD reproduction. The switching switch 75 is on the a side, for example, during LD reproduction, and switches to the b side on the basis of the disc discrimination information from the disc discrimination circuit 10 during LDD and CD reproduction. The audio output from the digital information demodulation system 14 is supplied to the output terminals 74L and 74R through the left and right mode switching switches 76L and 76R and the switching switches 75L and 75R.

As a result, normal audio signals are output from the output terminals 73L and 73R and output terminals 74L and 74R during LD playback. High-quality audio signals are output from the output terminals 74L and 74R during LDD and CD playback. Again, the normal audio signal is also output from the output terminals 73L and 73R.

The mode switching switches 76L and 76R are provided for switching the output mode of the audio signal of the digital audio system in the analog stage. In other words, the audio output from the digital audio demodulator 14 is good as the above-described output mode in the case of stereophonic. However, in the case of voice multiplexing, for example, the L (left) channel is Japanese and the R (right) channel is a foreign language. The voices output from the output terminals 74L and 74R can be switched to three output modes only for Japanese and foreign languages, Japanese and foreign languages by the mode changeover switches 76L and 76R operating. The driving of the mode switching switches 76L and 76R is performed separately in response to control information from an operation unit (not shown).

As the mode changeover switches 76L and 76R, relays that operate independently of each other are used. [0004] Normally, relays having one movable contact and two fixed contacts are sufficient to switch signals, but in this embodiment, one relay is used again. Relays with contacts and two stationary contacts are used. That is, if the L channel side relay 76L is described as an example, two sets of fixed contacts (S ₁₁ and S ₂₁ ) interlocked with each other and two sets of pairs fixed to the pair of movable contacts (S ₁₁ and S ₂₁ ) are installed. Composed of contacts S ₁₂ , 13, S ₂₂ , 23, the two most remote fixed contacts S ₁₂ , S _{23 of the} two fixed contacts become input terminals of two signals (left and right audio signals) The contact S ₁₁ is an output terminal. As a result, two gaps exist between the left and right signal lines, thereby making it possible to reliably prevent interference between the left and right signals.

Of course, the interference can be more reliably prevented by increasing the contact points and providing a larger gap.

In addition, although not shown in the drawing, a focus servo for controlling the position in the direction perpendicular to the disk surface of the pickup 12 with respect to the disk 5 or a tracking surge for controlling the position in the disk radius direction of the pickup 12 is shown. Of course, it is preferable to switch the signal processing system of the error signal when playing video discs (LDD, LD) and digital audio disc (CD). I can walk. The digital signal recorded on the CD or LDD includes not only audio information but also digitalized image information or computer control information.

As described above, the recording disc information reproducing apparatus according to the present invention monitors the memory use condition and controls the frequency of the read clock in response to the use condition. In this case, the output muting can be canceled immediately by optimizing the memory usage immediately after the instruction is terminated, and the jitter component included in the reproduced digital signal can be reliably suppressed to obtain a jitter-free digital signal after the muting is released. have.

Claims (1)

Demodulation means (22) for demodulating a reproduced digital signal, recording means (25) for recording the demodulation output of said demodulation means to a memory (24) in synchronization with a reproduced clock signal included in said reproduced digital signal; Clock generating means 27, 28 for generating a read clock signal for reading the stored information, and phase synchronizing means 23, 29, 31, 32, 27, for synchronizing the output of the clock generating means with the reproduction clock signal; 30), monitoring means 25 for monitoring the use situation in the memory and generating an output according to the use situation, and the monitoring means controlling the frequency of the read clock signal by the clock generating means in accordance with the output. A recording disc information reproducing apparatus characterized by having a control means (36).

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