JPS6171465A - Recording disc information reproducing device - Google Patents

Abstract

PURPOSE:To use in common a circuit of a demodulation system by switching a signal processing circuit of a reproduced digital signal depending on CD reproduction and LDD reproduction to apply a stable digital signal to the demodulation system in an reproduction. CONSTITUTION:A changeover switch 75 is thrown to the position (a) being normal state for, e.g., LD reproduction and changed over to the position (b) at LDD/CD reproduction based on disc discrimination information from a disc discrimination circuit 10. Then an audio output from a digital information demodulation system 14 is fed to output terminals 74L, 74R via left/right mode changeover switches 76L, 76R and 75L, 76R. As a result, a normal audio signal is outputted from output terminals 73L, 73R and the output terminals 74L, 74R, and a high sound quality audio signal is outputted from the output terminals 74L, 74R at LDD, CD reproduction and the normal audio signal is outputted further from the output terminals 73L, 73R at LDD reproduction.

Description

TECHNICAL FIELD The present invention relates to a recording disc information reproducing apparatus, and more particularly to a reproducing apparatus for reproducing recorded information on a recording disc on which digital signals are recorded.

BACKGROUND ART A so-called compact disk (hereinafter abbreviated as CD), which is a digital audio disk in which an audio signal is subjected to predetermined digital modulation processing and recorded as a pulse train, is known as a recording disk on which digital signals are recorded. Furthermore, recently, a method has been developed in which a pulse train signal obtained by digitizing an audio signal using a predetermined digital modulation method is superimposed on each FM modulated signal of a video signal and an audio signal (refer to the specification of Japanese Patent Application No. 1982-45780). Video discs (hereinafter abbreviated as LDD) have been developed.

In this recording method, the audio signal is made into two channels, 2.3tvlHz and 2°8MH2.
audio carriers are each FM modulated by two audio channel signals. The video signal is frequency-converted so that the sync tip is 7°6 MHz, the pedestal level is 8.1 MHz, and the white beak is 9.3 MHz. Then, the audio signal is further converted into PCM (Pulse Code Modulus).
The signal is digitized and converted into a pulse train signal using a modulation method such as .

This pulse train signal is, for example, EFM (Eight and OF
The signal is suitable for recording using the 3-11 modulation method, and the frequency spectrum is a frequency component of a pulse train having a width of 3 T to 11 T. Here, T indicates the bit period of the PCM signal, and the 3T pulse is approximately 720 KHz.

The maximum width of the 11T pulse is approximately 200 Kl-1z. Such a pulse train signal is superimposed on the video main carrier at a level of about 1/10 or less, and is slice-amplified near the zero-crossing point to become a pulse-width modulated signal, which is used as a recording signal.

RF (high frequency) obtained from a recording disk on which video signals and audio signals are recorded using the above recording method.
The frequency spectrum of the signal is as shown in FIG. In Fig. 1, the component indicated by 8 is a digitized audio signal component, the component indicated by B is an audio FM signal component, the component indicated by C is a color information component in a video FM signal, and the component indicated by D is a digitalized audio FM signal component. The luminance information component is −.

Since the dynamic range of the digitized audio signal can be approximately 90 dB or more, it is possible to improve the sound quality more smoothly than when recording and reproducing audio signals using the FM modulation method.

By the way, in a general demodulating device for a PCM digital signal in a CD playback device, the read clock is fixed,
On the other hand, by synchronizing the rotation of the recording disk in phase and reading out the information written to the -H memory using a write clock synchronized with the reproduction clock signal in synchronization with the read clock, jedder, which is a time axis fluctuation component, is removed. It is depicted as such.

On the other hand, when demodulating the digital signal extracted from the playback signal by the video playback device when playing the LDD, the playback signal is already synchronized with the reference signal for video synchronization, and the demodulation device in the conventional CD playback device When data is read from memory using a separate reference signal on the PGin modulation side, the reproduced video signal and the reproduced demodulated audio signal will be shifted in time due to a slight phase shift between the two reference signals. It will end up being put away.

Additionally, in the case of an LDD, during recording, the low frequency components of the digital signal are boosted and recorded in order to prevent the high frequency components of the digital signal from interfering with the FM video signal. It is necessary to perform compensation to reduce the range components.

Therefore, when developing a playback device that can play both CDs and LDDs, it is necessary to solve the above-mentioned problems when considering sharing the demodulation system for the purpose of reducing costs. be.

Summary of the Invention The present invention has been made in view of the above-mentioned points, and makes it possible to share the demodulation system by applying signal processing corresponding to the reproduced digital signal, whether playing a CD or an LDD. The purpose of the present invention is to provide a recording disc information reproducing device that has the following features.

A recording disk information reproducing apparatus according to the present invention includes a first recording disk on which predetermined information is subjected to predetermined digital modulation processing and is recorded in the form of a pulse train, and a video signal and an audio signal that are frequency-modulated and a predetermined digital signal, respectively. A recording disc information reproducing apparatus capable of reproducing a second recording disc recorded with a superimposed signal, the first signal processing circuit including an equalizer circuit for compensating for high frequencies of the reproduced digital signal, and the reproduced digital signal. a second signal processing circuit including a de-emphasis circuit that compensates for the low frequency range of the M1; a disc discrimination means for discriminating the type of recording disc to be reproduced; and a signal processing circuit of the M1 based on the discrimination result of the disc discrimination means. and selection means for selecting each of the second signal processing circuits when reproducing the second recording disk.

Example Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

FIG. 2 is a block diagram showing an embodiment of a recording disc information reproducing apparatus according to the present invention. Such a playback device is a CD
This is a so-called compatible player that can also play back ordinary video discs (hereinafter abbreviated as LD) on which video signals and audio signals are frequency-modulated and recorded, respectively. This player has a spindle motor 1 for driving the rotation of the LD and LDD, and a C
A spindle motor 2 for driving the D rotation is provided.

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

In order to detect the disc size of the disc 5 to be reproduced, for example, three detection sensors 6, 7 and 8 are provided corresponding to the disc size in the disc radial direction. The disc size for CDs is approximately 5 inches (1
2 cm>, and in the case of video discs (LD, LDD), there are two types of outer diameters: 8 inches and 12 inches. The outputs of the three detection sensors 6 , 7 and 8 are waveform-shaped by a waveform shaping circuit 9 and then supplied to a disk discrimination circuit 10 . As the detection sensor, for example, an optical sensor is used, but the detection sensor is not limited to this.

The disc discrimination circuit 10 determines whether the disc to be played is a CD or an LDD based on the detection outputs of the detection sensors 6.7 and 8.
It is determined which of the three types of disks, LD and LD. FIG. 3 shows a specific circuit groove configuration of this disc discriminating circuit 10. In this diagram, in the case of CD,
The minimum disk size is determined to be 12C11>,
The detection output of the innermost detection sensor 6 and the inverter 79.
The output of the AND gate circuit 78, which converts the inverted output of the detection sensor 7.8- through 80 into three-man power, becomes the CD discrimination information.

That is, the detection sensor 6 is on, and the other detection sensors 7.
8 is off, it is determined to be a CD. 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 passes through the OR gate circuit 69 and becomes the output of each of the AND gate circuits 70 and 71. In addition, a frame synchronization detection circuit 2 to be described later
A frame synchronization detection signal generated when a frame synchronization signal is detected from 1 becomes a value input to an AND gate circuit 71, and is also inverted by an inverter 72 and becomes a value input to an AND gate circuit 70. and detection sensor 7 or 8
When a detection output is generated and a frame synchronization detection signal is input, the AND gate circuit 71 outputs LDD discrimination information, and when the frame synchronization detection signal is not input, the AND gate circuit 70 outputs LD discrimination information. . This discrimination information is used to drive an indicator 11 that displays the type of disc, and as a switching signal for each ladder switch to be described later.

A pickup 12 for reading recorded information from the disk 5 is supported by a slider base (not shown) that is movable in the radial direction of the disk 5. It is driven by a drive mechanism (not shown). Read information read from the recording disk 5 by the pickup 12 is supplied to a digital information demodulation system 14, an analog audio demodulation system 15, and a video demodulation system 16 through an RF amplifier 13, respectively. RF amplifier 13
has a wide band of about 5 kHz to 14 MHz, and a single amplifier can amplify the reproduced P'CM audio signal, the reproduced FM audio signal, and the reproduced video signal.

The digital information demodulation system 14 is provided with a changeover switch 17 that changes depending on the type of disc to be reproduced.
Based on the disc information from , it switches to the A side in the case of an LDD, and to the B side in the case of a CD. That is, L.D.D.
The signal processing system for the reproduced digital signal is switched between reproduction and CD reproduction. During CD playback, the playback RF output is PCM audio information, and this PCM audio information is processed by an equalizer 18 into an MTF (Moculation
Transfer FLInCtiOn ) compensation is applied.

On the other hand, in the case of LDD, FM audio information and FM
PCM audio information included in the reproduced RF signal together with the video information is extracted by an LPF (low pass filter) 19 and supplied to a de-emphasis circuit 20. PCM
Audio information is, for example, an EFM signal, but if the digital signal is directly superimposed on an FM-modulated video signal during recording, the digital signal component will be interfered with by the low-frequency component of the FM video signal. Low frequency components are boosted and recorded. Therefore, during reproduction, the de-emphasis circuit 20 performs compensation by dropping the low-frequency components boosted during recording. As a result, the S/N ratio of the digital signal can be improved against low frequency noise during recording and reproduction.

Note that instead of switching the signal processing system using the changeover switch 17, the power supply to each signal processing system circuit is set to 0N.
A similar effect can be obtained by using 10FF.

The reproduced EFM signal that has passed through the changeover switch 17 is supplied to the EFM (I sub-circuit 22) via a frame synchronization detection circuit 21, and is also supplied to a reproduced clock extraction circuit 23. The signal is demodulated into a PCM digital signal by the EFM demodulation circuit 22 using the clock.

This demodulated signal is input to and output from a memory 24 such as a RAM (Random Access Memory) under the control of a memory controller 25, but at this time, the memory controller 25 is synchronized with the write clock, which is the frequency-divided output from the frequency divider 26 of the reproduced clock. and write.

Reading of stored information from the memory 24 is performed in synchronization with a read clock obtained by dividing the oscillation output of a vCO (voltage controlled oscillator) 27- in a PLL (phase locked loop) circuit by a frequency divider 28. It looks like this. The PLL circuit is the VCO2 mentioned above.
7. Frequency division output by frequency divider 29 of regeneration Otsuk and VCO
A phase comparator (P/C) 31 that uses the divided output of the frequency divider 27 of the oscillation output of 27, an LPF (low pass filter) 32 that receives this comparison output as input, and this LP
It is constituted by a changeover switch 33 that selectively supplies the output voltage of F32 and the reference voltage Vref+ to the VCO 27.

In the PLL circuit, the changeover switch 33 is set to the a side to change the output voltage of the LPF 32 during LDD playback, and is switched to the b side to set the reference voltage Vref+ to the VCO during CD playback, based on the discrimination result of the disc discrimination circuit 10 described above.
Supply to 27. As a result, during LDD playback, the read clock for reading stored information from the memory 24 is set to P.
The phase of the reproduced clock is synchronized by the LL circuit, and when the loop switch 59 described later is turned on (opened) during CD playback, the output of the phase comparator 31 becomes LP.
By driving the spindle motor 92 for driving the CD rotation through F77, the reproduced clock is phase-synchronized with the fixed clock obtained by the VCO 27 whose bias is in a fixed state.

The digital signal thus read out is converted into an analog audio signal by a D/A (digital/analog) converter 34, and then sent to an LPF 35L.

Left and right playback audio outputs are provided via 35R.

The usage status in the memory 24 is constantly monitored by the memory controller 25, and when the memory 24 overflows or becomes blank (no data), the controller 25 sends information indicating these statuses to the voltage generator 3.
Supply to 6. During LDD regeneration, this voltage generator 36
In response to the information indicating the usage status of the memory 24 from the memory controller 25, a positive control voltage is generated when the memory 24 overflows, and a negative control is generated when the memory 24 becomes blank]. , the frequency of the read clock is controlled by supplying the output voltage of the LPF 32 to the CO 27 via the changeover switch 33.

In this way, m of the data stored in the memory 24 is constantly monitored, and when there is an excess or deficiency in the capacity and processing capacity of the memory 24, a positive or negative control voltage m is generated to cause the PLL circuit to deal with the problem. By making this request, the memory 24 can always be maintained in a normal state.

In the analog audio demodulation system 15, the outputs of BPFs (band pass filters) 37L and 37R that pass only 2.3 MHz and 2.8 MH2 audio carrier components from the reproduced RF signal are sent to an FM demodulator 381.38R.
FM demodulation is performed in the de-emphasis circuit 39L.
, 39R as left and right playback audio outputs.

In the video demodulation system 16, only video information is extracted from the reproduced RF signal by a BPF & notch circuit 40. This BP
In the F&notch circuit 40, the EFM component and 2.3MHz, 2.8MHz included in the reproduced RF signal during LDD reproduction
The audio carrier component of z is actively removed. This extracted information is supplied to the FM demodulator 42 via the limiter circuit 41 and is FM demodulated. This demodulated output is sent to a dropout compensator (DQC) via an LPF43.
) 44, and dropout compensation is performed in the compensator 44. This dropout compensator 44 is, for example, an analog switch that is turned off by the detection output of a dropout sensor (DO8) 46 that detects a dropout based on a reproduced RF signal supplied via an HPF (bypass filter) 45. and a hold capacitor provided between this switch output end and a reference potential point. Therefore, when a lower dropout occurs, the level of the output of the LPF 43 immediately before the output of the dropout sensor 46 is bolded and sent to the next stage circuit, thereby performing dropout compensation. The output of this dropout compensator 44 becomes a video output.

The output of the dropout compensator 44 is sent to the horizontal sync separation circuit 4.
7, and the horizontal synchronizing signal is separated and output. This horizontal synchronization signal is supplied to phase comparators 48 and 49, and the phase difference with the reference signal output from the reference signal generator 50 is detected. The output of the phase comparator 48 serves as an input to the adder 51, and the output of the phase comparator 49 serves as another input to the adder 51 via an equalizer amplifier 52. The output of the adder 51 drives the LDD and the spindle motor 1 for driving the rotation of the LD via an equalizer amplifier 53 and a driver 54. This is the spindle servo system. Further, the output of the equalizer amplifier 52 is connected to a loop switch 55,
An actuator (not shown) built into the pickup 12 is driven via the changeover switch 56 and the driver 57.

By driving this actuator, a light spot for reading information is biased in the tangential direction of the recording track of the disk. This is a tangential servo system. The actuator may be a tangential mirror that rotates to deflect an optical spot for reading information in a direction tangential to the recording track of the disk, or a tangential mirror that deflects a lens in a direction perpendicular to the optical axis. The optical spot for information reading may be biased in the tangential direction of the recording track of the disk.

The loop switch 55 is turned on (closed) in response to a spindle lock signal output from the spindle lock detection circuit 58 when locking of the spindle servo system is substantially completed. That is, at the start of reproduction, first, the spindle motor 1 is driven by the output of the phase comparator 48, and coarse adjustment of the time axis (spindle servo) is performed.
When the locking of the spindle servo is substantially completed, the loop switch 55 is turned on, and the actuator is driven by the outputs of the four phase comparators to perform fine adjustment of the time axis (tangential servo).

According to this, residual jitter components that cannot be removed by the spindle servo system can be removed by the tangential servo system.

However, even in a full servo system with 1 tangency, jitter cannot be completely removed because the mechanical system such as the actuator drive mechanism cannot sufficiently follow the high-frequency component of residual jitter. Therefore, in the digital information demodulation system 14 mentioned above, P
By setting the cutoff frequency of the LPF 32 of the LL circuit lower than the maximum frequency of the band of the tangential servo lube to cut the high frequency component of residual jitter,
This means that residual jitter components can be removed. More preferably, by setting the cutoff frequency of the LPF'32 lower than the disk eccentricity frequency (30 to 8 Hz in the case of LDD), it is possible to completely eliminate jitter caused by disk eccentricity.

Although the spindle servo and tangential servo are performed based on the horizontal synchronization signal, similar effects can be obtained by performing the spindle servo and tangential servo based on the 3.58 MHz color subcarrier included in the reproduced FM video signal.

The above is a servo system when reproducing a video disc (LD[), LD), but when reproducing a CD, spindle servo is performed based on the output of the phase comparator 31 in the digital information demodulation system 14 described above. That is, the output of the phase comparator 31 drives the spindle motor 2 for driving the CD rotation via the loop switch 59 and the driver 60, which are turned on (open) during CD reproduction. Conventionally, the above-mentioned tangential servo was not performed during CD playback, but since the spindle 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, this In the example, HPF
A servo, that is, a tangential servo, in which the high frequency component of the time axis error signal extracted by the time axis error signal 61 drives the actuator in the pickup 12 via the changeover switch 56 and the driver 57 is also employed. The changeover switch 56 is set to the a side when playing an LDD or LD, and to the b side when playing a CD, based on the discrimination result of the disc discrimination circuit 10.
Switch to the side.

Note that the tangential servo during CD playback is performed based on the divided output of the reproduced clock extracted by the reproduced clock extraction circuit 23, but the frame synchronization signal detected by the frame synchronization detection circuit 2-1 is Even if it is performed based on the frequency-divided output of , the same effect can be obtained since the frame synchronization signal and the reproduced clock are in a synchronous relationship.

The output of the spindle lock detection circuit 58 is connected to the inverter 62.
This signal is inverted and becomes the sole power of the OR gate circuit 63 as a spindle unlock signal indicating that the spindle servo system is not in the locked state.

A random access information signal generated at the time of a random access command such as a scan, narch, or jump is supplied as an input to the OR gate circuit 63. Furthermore, the LDD information output from the disk discrimination circuit 10 is also input to the OR gate circuit 63.

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

A specific circuit configuration of the recovered clock extraction circuit 23 is shown in FIG. In this figure, the reproducing EFM Shintan has phase comparator 6.
5, the phase difference with the oscillation output of ■C○ (voltage controlled oscillator) 66 is detected, and the phase difference signal is L P l=
67 and a changeover switch 68 to the VCO 66 . As described above, a PLL circuit that generates a reproduced clock is configured.

The changeover switch 68 is normally located on the a side and supplies the output of the LPF 67 to the VCO 66, but the control command circuit 6 described above
When a command signal is output from 4, it switches to the b side in response to this command signal and supplies a predetermined reference voltage ``re''2 to vC○66.

That is, when the spindle servo is not in a locked state or when the information reading light spot jumps tracks due to a random access command such as scan, narch, or jump, the reference voltage Vref2 is applied to the VCO 66 to reproduce its oscillation frequency. By fixing the clock frequency to a value close to the clock frequency, it is possible to hasten the lock-in of the regeneration lock of the bond after the spindle servo is locked or the random access command is released.

Referring again to FIG. 2, the audio output section includes a pair of left and right output terminals 73L and 73R of the analog audio output system.
A pair of left and right output terminals 74L and 74R of a digital audio output system are provided. Output terminal 73L,
The audio output from the analog audio demodulation system 14 is supplied to 73R. This audio output is sent to output terminals 74L and 74 via a changeover switch 75 during LD playback.
It is also supplied to R. The changeover switch 75 is located on the a side when playing an LD, for example, as a normal state.

When playing a CD, the switch is switched to the b side based on the disc discrimination information from the disc discrimination circuit 10. The audio output from the digital information demodulation system 14 is controlled by left and right mode changeover switches 76L, 76R and changeover switches 75L, 75.
It is supplied to the output terminal 74L=748 via R.

As a result, during LD playback, the output terminal 73L.

Normal audio signals are output from 73R and output terminals 74L and 74R, and during LDD and CD playback, high-quality audio signals are output from output terminal 741.74R, and when LDD is played back, normal audio signals are output from output terminals 73m and 73R. An audio signal will be output.

The mode changeover switches 76L and 76R are provided to change over the output mode of digital audio audio signals in an analog stage. In other words, if the audio output from the digital audio demodulation system 14 is stereophonic, the above-mentioned output mode will suffice, but in the case of audio multiplexing, for example, the L (left) channel may be Japanese and the R (right) channel may be the same. A mode selector switch 76L that is in a foreign language and operates independently of each other;
76R allows the audio output from the output terminals 74L and 74R to be switched to three output modes: Japanese and foreign languages, Japanese only, and foreign languages only. The mode changeover switches 76L and 76R are driven separately according to control information from an operation section (not shown).

Relays that operate independently are used as the mode changeover switches 76L and 76R. Normally, a relay with one movable contact and two fixed contacts is sufficient for signal switching, but in this embodiment, a relay with one movable contact and two extra fixed contacts is used. is being used. That is, to explain the relay 761 on the L channel side as an example, there are two sets of movable contacts s11°S21 that interlock with each other, and these two sets of movable contacts SI+, S2+.
two sets of fixed contacts 512, one pair provided for each;
13, sη, and 23, of the two sets of fixed contacts, the two most distant fixed contacts Slz, 823 serve as input ends for the two signals (left and right audio signals), and one movable contact S I+ serves as the output end. It has become. According to this, since two gaps exist between the left and right signal lines, crosstalk between the left and right signals can be reliably prevented. Of course, crosstalk can be more reliably prevented by increasing the number of contacts and providing more gaps.

Although not shown in the figure, there is a focus servo system 11 that controls the position of the pickup 12 relative to the disk 5 in a direction perpendicular to the disk, and a focus servo system 11 that controls the position of the pickup 12 relative to the disk 5.
Of course, a tracking servo system is also provided to control the position of the second disc in the radial direction, and these servo systems also generate error signals when playing a video disc (LDD, LD>) and when playing a digital audio disc (CD). It is preferable to switch the processing system, so that good servo can be performed regardless of the type of disc being played.

In addition, the digital signal recorded on CD or LDD is
In addition to audio information, it also includes digitized image reports and control information for computers It, II, and III.

As explained above, according to the recording disc information reproducing apparatus according to the present invention, the signal processing circuit for the reproduced digital signal is switched between CD reproduction and LDD reproduction, and a stable digital signal can be obtained during either reproduction. Since the signal can be supplied to the demodulation system, the demodulation system circuit can be shared, contributing to cost reduction of compatible players.

[Brief explanation of drawings]

Figure 1 shows the R [signal frequency 2 is a block diagram showing an embodiment of the recording disc information reproducing apparatus according to the present invention; FIG. 3 is a block diagram showing a specific circuit configuration of the disc discrimination circuit in FIG. 2;
FIG. 4 is a block diagram showing a specific circuit configuration of the recovered clock extraction circuit in FIG. 2. Explanation of symbols of main parts 1...Swiss spindle motor 2 for LD and LDD
...CD spindle motor 5...Recording disc 10...Disc discrimination circuit 12...Pickup 14...Digital information demodulation system 15...・・・
・Analog audio demodulation system 16...Video demodulation system

Claims (1)

[Claims] A first recording disk on which predetermined information has been subjected to a predetermined digital modulation process and is recorded in the form of a pulse train, and a second recording disk on which a predetermined digital signal and a video signal and an audio signal, respectively, are frequency-modulated and are superimposed and recorded. A recording disc information reproducing apparatus capable of reproducing data from a recording disc, the first signal processing circuit including an equalizer circuit that compensates for the high frequency range of the reproduced digital signal, and a de-emphasis circuit that compensates for the low frequency range of the reproduced digital signal. a second signal processing circuit including a second signal processing circuit, a disc discriminating means for discriminating the type of recording disc to be reproduced, and a second signal processing circuit when reproducing the first recording disc based on the determination result of the disc discriminating means. A recording disc information reproducing apparatus characterized by comprising: selecting means for selecting each of the second signal processing circuits when reproducing the second recording disc.