JPH0215465A - Pcm signal reproducing device for optical disk player - Google Patents

Abstract

PURPOSE:To obtain the optimum playability and an error rate for the respective disks of a CD and a VD by switching the sensitivity of the slice level control of a data slicing circuit to the optimum values of the respective disks according to the disks. CONSTITUTION:The recording signal of an optical disk 1 is read by a pickup 2, and the output signal of the pickup 2 is inputted to a comparator 11 and made into a pulse. A comparator level is controlled by a control signal from a slice level control circuit 16 which is set so as to be the optimum one for the CD. The signal made into the pulse inputs to a PLL8 and inputs a PCM signal demodulating circuit 9 together with a clock to synchronize with the signal, and a demodulated audio signal outputs from a terminal 10. At the time of reproducing the VD, a switch 5 is set to an A side, and a switch 17 is set to a C side, respectively. The output of an EMF filter 4 inputs to the comparator 11, and only the PCM signal component of the output passes through the comparator 11. The signal inputted to the comparator 11 is made into the pulse by another control signal from the circuit 15 made into the optimum state for the VD, the signal made into the pulse passes through the circuit 9, and another demodulate audio signal are outputted.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a PCM signal reproducing device for an optical disc player.

2. Description of the Related Art A compatible optical disc player capable of playing multiple types of optical discs has a first disc (hereinafter referred to as CD) on which a PCM signal of audio or data is optically recorded, and a first disc (hereinafter referred to as CD) on which a PCM signal of audio or data is optically recorded, and an FM-modulated video signal. Although it is possible to play back a second optical disc (hereinafter referred to as VD) in which audio or data is multiplexed with a PCM signal and optically recorded on the same track, an example of a conventional PCM signal playback device will be explained. do.

FIG. 2 is a block diagram showing the configuration of a PCM signal reproducing device for a compatible optical disc player. 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 switch, 6 is a control circuit, 7 is a data slice circuit, 8 is a PLL, and 9 is a PCM
In the signal demodulation circuit, 10 is a terminal.

FIG. 3 is a block diagram showing the configuration of a conventional data slice circuit (a detailed block diagram of the data slice circuit 7 in the block diagram of FIG. 1).

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 constructed as described above will be explained below.

In FIG. 2, a pickup 2 converts signals recorded on an optical disc 1 into electrical signals. When playing a CD, the switch 5 is set to the B side. Therefore, the read information signal output from the pickup is directly input to the data slice circuit 7 and is converted into pulses. The pulsed signal is inputted to a PLL circuit 8, and then inputted 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 IO.

When playing a DVD, read tl of pickup 2.
? The i signal contains a PCM signal component and an FM variable 1 signal (
Among the respective frequency components, the PCM signal component is below 2 M IIZυ.

At this time, switch 5 is set to the A side, so EF
The output of the M 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. Is the read information signal input to the data slice circuit 7 the same data slice circuit as used when playing a CD? , processed by the PLL circuit 8 and input to the digital audio demodulation circuit 9. As a result, the demodulated audio signal is output from the terminal 10.

The i1J control circuit 6 assumes that the optical disc 1 to be reproduced is a CD.

A movement is made to change the switch 5 according to either of the VD and VD.

The data slice circuit 7 is configured as shown in FIG. The read iff 91 signal from optical disk 2 is sent to comparator 1.
1 and is converted into a PCM signal.

Here, if the bit pattern of a CD or VD PCM signal is ideal, the average signal level is coated so as not to include a DC component, so the data slice level may be set to the middle of the signal. However, DC fluctuations occur due to manufacturing errors in exposure and development of the mask disk, or scratches or fingerprints on the disk surface. The slice level control circuit 12 controls the slice level so that the DC component of the PCM signal becomes zero even when C fluctuation occurs as described above. The lower the sensitivity of this control is, the worse the ability to follow DC fluctuations is, and the higher the sensitivity is, the worse it is against noise. Therefore, the control sensitivity is determined by taking these conditions into consideration.

However, the PCM band signal extracted from the disc is C
D and VD are different in the above two conditions. In the case of a CD, since the PCM signal is recorded as a hit on the disc, the influence of DC fluctuations due to errors in disc mastering remains in effect. Also, the linear velocity is 1.2 to 1
．． Since it is 4m/see, the influence of defects such as scratches and fingerprints on the disc surface is large, but in terms of S/N,
Better than VD. Therefore, the control sensitivity of the slice level should be set high with emphasis on followability to DC fluctuations.

On the other hand, in the case of VD, the PCM signal is the FM signal of the video signal.
Since it is multiplexed into the low frequency band of the modulated signal, it is recorded on the disk as a low frequency component of bits. Therefore, the influence of DC fluctuations due to pit variations etc. during disk mastering is less than that of CDs (also, since the linear velocity is 11 to 12 m/sec, the influence of defects on the disk surface is much less than that of CDs). However, in order to prevent crosstalk between the video signal and the PCM signal, the PCM signal is approximately 27 d
Since it is recorded at a lower B, it is very disadvantageous in terms of S/N compared to a CD. Therefore, the control sensitivity of the slice level should be set to a low level, taking into consideration the margin for noise fluctuations and level fluctuations.

As described above, CDs and VDs have contradictory requirements regarding the slice level control of the data slice circuit.

Problems to be Solved by the Invention However, in a compatible optical disc player with such a configuration, although the S/N of the PCM band signal and the DC fluctuation due to defects are different between CD and VD,
Since PCM is performed using a data slicing circuit with the same control sensitivity, it is optimal for each disc, such as improving the playability against defects of a CD, but the error rate against noise of a VD worsens. The drawback was that it was not possible to ensure playability or error rate.

Means for Solving the Problems In order to solve the above problems, an optical disc player of the present invention includes a pickup that converts a signal recorded on an optical disc into an electrical signal, a filter that extracts a PCM signal component from the pickup output, and a CD player. , VD, and a data slice circuit that can switch control sensitivity according to a switching signal.

Operation The present invention achieves optimal playability for each disc by switching the control sensitivity of the slice level control of the data slicing circuit to the optimal value for each disc depending on the disc, CD or VD, with the above-described configuration. It becomes possible to achieve a high 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. 3 is a block diagram showing the configuration of a compatible optical disc player according to an embodiment of the present invention. In the figure,
■ is an optical disk, 2 is a pickup, 3 is a spindle motor, 4 is an EFM filter, 5 is a first switch, 6 is a control circuit, 11 is a comparator, 15 is a first slice level control circuit, 16 is a second slice A level control circuit, 17 is a second switch, 8 is a PLL, 9 is a PCM signal demodulation circuit, and 10 is a terminal.

The operation of the optical disc player according to one embodiment of the present invention constructed as described above will be explained below.

In FIG. 1, a pickup 2 converts signals recorded on an optical disc 1 into electrical signals. When playing a CD, the first switch 5 is set to the B side. Therefore, the read information signal output from the pickup is directly input to the comparator 11 for data slicing and is converted into a pulse.

Also, since the second switch 17 is set to the D side, the C
The comparator level is controlled by a control signal from the second slice level control circuit 16, which is set to be optimal for D. The pulsed signal is input to PLL8,
PCM signal demodulation circuit 9 with a clock synchronized with the signal
is input. As a result, the demodulated audio signal is output from the terminal 10.

When playing a VD, the read information signal of the pickup 2 includes a PCM signal component and an FM modulated video signal, and the frequency component of the PCM signal component is 2 MHz or less, and the FM modulated video signal is 3 MHz. It is as follows. At this time, the first switch 5 is set to the lower position, 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. Further, the second switch 17 is set to the C side. Therefore, the comparator level is controlled by a control signal from the first slice level control circuit 15 that is set to be optimal for VD. The read information signal input to the comparator is pulsed and PLL8. It is processed by the PCM signal demodulation circuit 9.

As a result, the demodulated audio signal is output from the terminal 10.

The control circuit 6 assumes that the optical disc 15 to be reproduced is a CD.

The first switch 5 and the second switch
The switching of the switch 17 is controlled.

As described above, one embodiment of the present invention includes a pickup, a spindle motor, an EFM filter, a first switch, a control circuit, a comparator, a first slice level control circuit, and a second slice level control circuit. By providing a circuit and a second switch, it is possible to perform data slicing by switching to the optimal slice level control sensitivity for CDs and VDs, thereby achieving the optimal playability and error rate for each disc. It is possible to provide a compatible optical disc player that can ensure the following.

Effects of the Invention As described above, the optical disc player of the present invention includes a pickup that converts a signal recorded on an optical disc into an electrical signal, a filter that extracts a PCM signal component from the pickup output, and a CD.

By being equipped with a control circuit that discriminates and switches between CD and VD, and a data slice circuit that can switch the slice level control sensitivity according to the switching signal, it is possible to
By switching the slice level control sensitivity for each disk of D, appropriate data slicing is performed, making it possible to ensure optimal playability and error rate.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an optical disc player according to an embodiment of the present invention, FIG. 2 is a block diagram showing the configuration of a conventional optical disc player, and FIG. 3 is a block diagram showing the 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
...PLL, 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)

[Claims] A first optical disk on which a PCM signal of audio or data is recorded and a second optical disk on which an FM-modulated video signal and a PCM signal of audio or data are multiplexed and recorded on the same track. A PCM signal reproducing device for an optical disc player, which includes a data slice circuit that pulses a PCM band read information signal obtained from an optical disc, and slice level control that controls the slice level of the data slice circuit according to an input signal. A PCM signal reproducing device for an optical disc player, characterized in that the control amount is switched for each of the above-mentioned different optical discs, and the optimum value for each disc is reproduced.