JP2668954B2 - PCM signal reproduction device for optical disk player - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a PCM signal reproducing device for an optical disk player.

2. Description of the Related Art In a compatible optical disc player capable of reproducing plural types of optical discs, for example, a first disc (hereinafter referred to as a CD) on which a signal obtained by converting voice or data into PCM is optically recorded and an FM-modulated video signal are recorded. Although it is possible to play back a second optical disc (hereinafter referred to as VD) that is optically recorded on the same track by multiplexing a signal obtained by converting voice or data into PCM, an example of a conventional PCM signal playback device will be described. I do.

FIG. 2 is a block diagram showing a configuration of a PCM signal reproducing device of a compatible optical disc player. In the figure, 1 is an optical disc, 2 is a pickup, 3 is a spindle motor, 4 is an EFM filter, 5 is a switch, 6 is a control circuit, 7 is a data slice circuit, 8 is a PLL, 9 is a PCM signal demodulation circuit, and 10 is a terminal. is there.

FIG. 3 is a block diagram showing a configuration of a conventional data slice circuit (detailed block diagram of the data slice circuit 7 in the block diagram of FIG. 2). In the figure, 11 is a comparator, 12 is a slice level control circuit, and 13 and 14 are terminals.

The operation of the conventional PCM signal reproducing apparatus for a compatible optical disc player configured as described above will be described below.

In FIG. 2, a pickup 2 converts a signal recorded on an optical disk 1 into an electric signal. When playing a CD, the switch 5 is set to the B side. Therefore, the read information signal output of the pickup is directly input to the data slice circuit 7 and is pulsed. The pulsed signal is input to a PLL circuit 8 and is input to a digital audio demodulation circuit 9 together with a clock synchronized with the signal. As a result, a demodulated audio signal is output from the terminal 10.

When the VD is playing, the read information signal of the pickup 2 includes a PCM signal component and an FM modulation signal (video signal and audio signal).
The signal component is less than 2 MHz. At this time, since the switch 5 is set to the A side, the output of the EFM filter 4 is input to the data slice circuit 7. The EFM filter 4 passes only the PCM signal component from the read information signal output of the pickup 2 and performs de-emphasis. The read information signal input to the data slice circuit 7 is input to the PCM signal demodulation circuit 9 that is processed by the same data slice circuit 7 and PLL circuit 8 as during CD reproduction and demodulates a digital audio signal. As a result, a demodulated audio signal is output from the terminal 10.

The control circuit 6 functions to switch the switch 5 according to whether the optical disc 1 to be reproduced is CD or VD.

The data slice circuit 7 is configured as shown in FIG. A read information signal from the optical disk 2 is input to a comparator 11 and converted into a PCM signal. Here, if the pit pattern is ideal for the CDM and VD PCM signals, the average signal level is DC.
Since the coding is performed so as not to include the components, the slice level of the data may be set at the middle of the signal. However, DC fluctuations occur due to manufacturing errors in exposure and development of the master disk, scratches on the disk surface, fingerprints, and the like. The slice level control circuit 12
The slice level is controlled so that the DC component of the PCM-converted signal becomes zero even when a DC fluctuation occurs. The lower the sensitivity of this control, the worse the followability to DC fluctuations, and the higher the sensitivity, the more disadvantageous to noise. Therefore, the control sensitivity is determined by the balance of those conditions.

However, the PCM band signal extracted from the disc is CD,
VD differs in the above two conditions. PC for CD
Since the M signal is recorded as a disk pit,
The effects of DC fluctuations due to errors in disk mastering still work. Moreover, since the linear velocity is 1.2 to 1.4 m / sec, it is greatly affected by defects such as scratches on the disk surface and fingerprints, but it is superior to VD in terms of S / N. Therefore, the control sensitivity at the slice level should be set higher with emphasis on follow-up to DC fluctuation.

On the other hand, in the case of VD, the PCM signal is multiplexed in the low frequency band of the FM-modulated signal of the video signal, so that it is recorded as a low frequency component of pits on the disc. Therefore, due to pit variations in disc mastering
The effect of DC fluctuation is smaller than that of CD, and the linear velocity is 11
Since the speed is about 12 m / sec, the influence of defects on the disk surface is far less than that of a CD. However, in order to prevent crosstalk between the video signal and the PCM signal, the PCM signal is recorded with a reduction of about 27 dB with respect to the video signal.
In terms of N, it is very disadvantageous compared to CD. For this reason, the slice level control sensitivity should be set to a low value with an emphasis on noise fluctuation and margin of level fluctuation.

As described above, regarding the slice level control of the data slice circuit, conflicting demands are made between CD and VD.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention However, in a compatible optical disc player having such a configuration, the S / N or the defect of the PCM band signal causes
Even though the DC fluctuation is different between CD and VD, it is converted into PCM by the data slice circuit with the same control sensitivity, so if the playability for CD defects is improved,
There is a drawback in that it is not possible to secure the optimum playability and error rate for each disc, as the error rate for VD noise becomes worse.

Means for Solving the Problems In order to solve the above problems, a PCM signal reproducing apparatus for an optical disk player of the present invention multiplexes an FM-modulated video signal and a PCM signal of voice or data into the same track. A PCM signal reproducing device of an optical disc player for reproducing a first optical disc on which recording is performed and a second optical disc on which a signal obtained by converting sound or data into PCM is recorded. A data slicing circuit that controls a level according to an input signal to pulse the data includes a comparator, a first slice level control circuit in which a slice level control sensitivity is set so as to be optimum for reproduction of a first optical disc, and a first slice level control circuit. A second slice level control circuit which sets a slice level control sensitivity so as to be optimal for reproduction of the second optical disk; Optical disc first the other corresponds to be done is a configuration that pulsing the input digital signal to control the comparator by one of the second slice level control circuit.

The present invention, in the above configuration, by switching the slice level control circuit according to the disc type of the CD, VD to be reproduced, the slice level control sensitivity of the data slice circuit is set to the optimum value for each disc. It is possible to realize the optimum playability and error rate.

Embodiment Hereinafter, a compatible optical disc player according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of a compatible optical disc player according to one embodiment of the present invention. In the figure, 1 is an optical disk, 2 is a pickup, 3 is a spindle motor, 4 is an EFM filter, 5 is a first switch, and 6
Is a control circuit, 11 is a comparator, 15 is a first slice level control circuit, 16 is a second slice level control circuit, 17
Is a second switch, 8 is a PLL, 9 is a PCM signal demodulation circuit, 10
Is a terminal.

The operation of the optical disk player configured as described above according to one embodiment of the present invention will be described below.

In FIG. 1, a pickup 2 converts a signal recorded on an optical disk 1 into an electric signal. When playing a CD, the first switch 5 is set to the B side. Therefore, the read information signal output of the pickup is directly input to the comparator 11 for the data slice, and is pulsed.

Also, since the second switch 17 is set to the D side,
The comparator level is controlled by a control signal from the second slice level control circuit 16 which is set so as to be optimal to the above. The pulsed signal is input to the PLL 8 and is input to the PCM signal demodulation circuit 9 together with the clock synchronized with the signal. As a result, a demodulated audio signal is output from the terminal 10.

When the VD is reproduced, the read information signal of the pickup 2 includes the PCM signal component and the FM modulated video signal, the frequency component of the PCM signal component is 2 MHz or less, and the FM modulated video signal is 3 MHz. That is all. At this time, the first switch 5 is set to the A side, and the output of the EFM filter 4 is input to the comparator 11. The EFM filter 4 passes only the PCM signal component from the read information signal of the pickup 2 and performs de-emphasis. Also, the second switch
17 is set on the C side. Therefore, the comparator level is controlled by the control signal from the first slice level control circuit 15 set to be optimum for VD. The read information signal input to the comparator is pulsed and processed by the PLL 8 and PCM signal demodulation circuit 9. As a result, a demodulated audio signal is output from the terminal 10.

The control circuit 6 controls the first switch 5 and the second switch 5 according to whether the optical disk 15 to be reproduced is CD or VD.
Controls 17 switches.

As described above, in the embodiment of the present invention, the data slicing circuit for pulsing the read information signal of the PCM band obtained from the optical disc by controlling the slice level according to the input signal is composed of the comparator and the first optical disc reproducing device. A first slice level control circuit in which the slice level control sensitivity is set to be optimal for the first optical disk and a second slice level control sensitivity in which the slice level control sensitivity is set to be optimal for the second optical disk reproduction.
CD and VD
Thus, it is possible to provide a compatible optical disk player that can switch to the optimum slice level control sensitivity and perform data slicing, and can secure the optimum playability and error rate for each disk. it can.

As described above, according to the PCM signal reproducing device of the optical disk player of the present invention, the data slice circuit for pulsing the read information signal of the PCM band obtained from the optical disk by controlling the slice level according to the input signal is used. , A comparator, a first slice level control circuit that sets the slice level control sensitivity to be optimum for the first optical disk reproduction, and a slice level control sensitivity to be optimum for the second optical disk reproduction By providing the second slice level control circuit, an appropriate data slice is performed by switching the slice level control sensitivity for each of CD and VD disks, and the optimum playability and error rate are secured. Becomes possible.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an optical disc player according to an embodiment of the present invention, FIG. 2 is a block diagram showing a configuration of a conventional optical disc player, and FIG. 3 is a block diagram showing a configuration of a conventional data slice circuit. It is. 1 ... Optical disc, 2 ... Pickup, 3 ... Spindle motor, 4 ... EFM filter, 5 ... Switch, 6
…… Control circuit, 7 …… Data slice circuit, 8 …… PL
L, 9 ... PCM demodulation circuit, 11 ... Comparator, 12 ... Slice level control circuit, 15 ... First slice level control circuit, 16 ... Second slice level control circuit, 17 ...
Second switch.

Claims (1)

(57) [Claims] 1. A first optical disc in which an FM-modulated video signal and a signal obtained by converting voice or data into PCM are multiplexed and recorded on the same track, and a second optical disc in which a signal obtained by converting voice or data into PCM is recorded. A PCM signal reproducing device of an optical disk player for reproducing an optical disk, wherein a data slice circuit for pulsing a read information signal of a PCM band obtained from the optical disk by controlling a slice level according to an input signal, a comparator, and A first slice level control circuit in which a slice level control sensitivity is set to be optimum for the first optical disk reproduction, and a second slice level control sensitivity in which a slice level control sensitivity is set to be optimum for the second optical disk reproduction. The first or second slice level control circuit corresponding to the optical disc to be reproduced. A PCM signal reproducing device for an optical disk player, characterized in that the comparator is controlled by any one of the paths to pulse the input digital signal.