JP2602348B2 - Optical disk recording and reproducing apparatus and monitor circuit of optical disk recording and reproducing apparatus - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk device, and more particularly, to reproducing a recording signal when recording on a write-once (WO) optical disk and monitoring the recording signal simultaneously with recording. The present invention relates to a possible optical disk device.

[Prior Art] Conventionally, in order to record an audio signal on an optical disk, a digital audio signal is modulated into an EFM signal by an EFM encoder and output, and the output is input to a cutting machine of the optical disk.

Until now, there has been only a reproduction-only CD player as shown in FIG.

When monitoring the EFM signal at the time of recording, the signal obtained by the optical pickup 1 was amplified by the RF circuit 2 and shaped by the EFM comparator 3 in the digital signal processing circuit 4 of a circuit dedicated to reproduction shown in FIG. Instead of inputting an EFM signal,
Input EFM signal during recording.

The digital signal processing circuit 4 outputs a digital audio signal obtained by demodulating the EFM signal to the digital filter 5.

The digital filter 5 processes the input signal and outputs the processed signal to the DA converter 6.

The DA converter 6 converts the input digital signal into an analog signal and outputs the analog signal to the amplifier 7.

The amplifier 7 drives the speaker 8 by amplifying the input analog signal.

When switching from the playback state to the recording state using the conventional playback circuit described above, the digital signal processing input is played back.
When switching from the EFM signal to the recording EFM signal, at that moment, the data of the reproduction EFM signal is stored in the digital signal processing RAM, and the data of the recording EFM signal input thereafter becomes erroneous data.

For this reason, error correction cannot be performed inside the digital signal processing circuit, and the demodulation operation is stopped, and monitoring may not be performed.

In addition, the EFM signal is recorded while monitoring using such a reproduction circuit, and when the recording is stopped, the recording is interrupted at an arbitrary time. Is not continuous.

[Problems to be Solved by the Invention] The present invention has been made to solve the above-mentioned problems, and a monitor circuit of an optical disk device that does not stop demodulation work when switching from a reproduction state to a recording state is provided. The purpose is to provide.

It is another object of the present invention to provide an optical disk apparatus that controls the timing of turning off a laser circuit by a signal output from a digital signal processing circuit.

[Means for Solving the Problems] A monitor circuit of an optical disk recording / reproducing apparatus according to the present invention includes a digital signal processing circuit for inputting an EFM signal obtained from an optical pickup at the time of reproducing a rewritable optical disk. EFM signal input for playback and recording E
In an optical disc recording / reproducing device that enables monitoring of FM signals, the recording EFM signal is input to the digital signal processing circuit via a mute circuit and the recording EFM signal is switched for a certain period of time when switching from the playback state to the recording state. It is configured to perform signal processing after muting.

Also, the optical disk recording / reproducing apparatus of the present invention
In an optical disc recording / reproducing apparatus that can input and reproduce an EFM signal to a digital signal processing circuit, a synchronization signal of a subcode signal output from the digital signal processing circuit is detected, and a predetermined signal is detected from the synchronization signal of the subcode signal. EFM
The function is such that the laser circuit is turned off after recording the frame. [Function] When switching from the reproduction to the recording state, the recording EFM signal is muted for a certain period of time. The RAM for data storage becomes empty and its R
Since the recording EFM signal is input to the AM, no data error occurs and demodulation does not stop.

The timing for stopping the recording is determined by turning off the laser circuit after recording a predetermined frame based on the synchronization signal of the subcode signal output from the digital signal processing circuit.

Therefore, when recording, if the data of the EFM frame next to the data recorded in the predetermined EFM frame is recorded from the synchronization signal of the subcode data, the recorded subcode data becomes continuous at the recording restart position. .

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

 FIG. 1 is a circuit diagram showing an embodiment of the present invention.

In the figure, portions having the same functions as those shown in the conventional reproducing circuit are denoted by the same reference numerals as those used in FIG. 4, and detailed description thereof will be omitted.

In this embodiment, a digital signal processing circuit 4 converts an EFM signal obtained by amplifying a signal obtained by an optical pickup 1 by an RF circuit 2 and shaping by an EFM comparator 3 and a signal such as U-matic and DAT by an EFM encoder 12. And an EFM signal that modulates the laser power in the laser drive circuit 13 are selected by the analog switch 10 and input.

The analog switch 10 operates on the output of the microcomputer 11.

A mute circuit 9 is interposed between the analog switch 10 and the digital signal processing circuit 4.

The mute circuit 9 includes a resistor 9a as shown in detail in FIG.
Of the digital signal processing circuit 4 is connected to the collector of the digital transistor 9b.
Is a circuit whose emitter is connected to ground, and the base current of the digital transistor 9b is
Supplied from 11 output terminals.

The digital signal processing circuit 4 includes a PLL that is phase-synchronized with a synchronization signal included in the EFM signal. An EFM lock signal indicating that the PLL is synchronized is input to the microcomputer 11.

The microcomputer 11 further receives the EFM lock signal detected by the digital signal processing circuit 4 and the synchronization signals S0 and S1 of the subcode signal.

The laser drive circuit 13 has a reproduction state in which a constant low-power laser is emitted and a recording state in which the laser output is modulated by an EFM signal. The two states are selected by the output of the microcomputer 11.

In the above configuration, when playing the optical disc, the microcomputer 11 sets the analog switch 10 to the EFM.
Connected to the comparator 3 side, the laser drive circuit 13 supplies a constant low power to the laser diode of the optical pickup 1, and a signal recorded on the optical disk is taken out from the optical pickup 1 and reproduced.

When changing from the playback state to the recording state, the laser drive circuit
13 is set in a recording state by the microcomputer 11, and the analog switch 10 is switched to the EFM encoder 12 side.

At this time, the analog switch 10 and the mute circuit 9
Is controlled by the microcomputer 11, and a flowchart of the microcomputer operation is shown in FIG.

When this routine is executed, first, in step S1, the analog switch 10 is switched to the EFM encoder side.

Next, in step S2, the EFM lock signal is observed, and P
It is determined whether the LL has entered the synchronous lock state. If the LL is not in the lock state, the process proceeds to step S3. If the LL is in the lock state, the subroutine ends.

In step S3, it is determined whether a predetermined period has elapsed.If the predetermined period has elapsed, the process proceeds to step S7,
Error processing is performed, and the recording operation is interrupted. This error processing is performed when an EFM signal is not input.

If it is determined in step S3 that the predetermined period has not elapsed, the process proceeds to step S4, and the mute circuit is turned on.
That is, the EFM signal is cut by the mute circuit.

Next, the process proceeds to step S5, and waits for a predetermined time to elapse.

Next, the process proceeds to step S6, and after the mute circuit is turned off, step S2 is repeated.

As described above, the recording EFM signal is muted for a certain period of time, and during that time, the data storage RAM of the digital signal processing circuit becomes empty, and the recording EFM signal is input to the RAM. In addition, demodulation does not stop.

When stopping the recording, after detecting the sub-code signals S0 and S1 outputted from the digital signal processing circuit, the recording is stopped after the predetermined frame is recorded.

Therefore, when additional recording is performed, the subcode data S0, S
Recording starts from the subcode data of the EFM frame next to the subcode data recorded in the predetermined EFM frame from 1 and the recorded subcode data continues at the recording restart position.

[Effect of the Invention] As described above, according to the monitor circuit of the optical disk device of the present invention, the EFM signal at the time of recording can be monitored simply by adding a simple circuit to the reproduction circuit.

Further, it is possible to set a timing for turning off the laser by a signal obtained by demodulating the recording EFM signal by the digital signal processing circuit.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an optical disk apparatus according to an embodiment of the present invention, FIG. 2 is a circuit diagram showing a mute circuit in the embodiment, and FIG. 3 shows a part of the operation of the microcomputer in the embodiment. FIG. 4 is a circuit diagram showing an example of a conventional optical disk reproducing apparatus. DESCRIPTION OF SYMBOLS 1 ... Optical pickup, 2 ... RF circuit, 3 ... EFM comparator, 4 ... Digital signal processing circuit, 5 ... Digital filter, 6 ... DA converter, 7 ... Amplifier, 8 ...
... speaker, 9 ... mute circuit, 10 ... analog switch, 11 ... microcomputer, 12 ... EFM encoder, 13 ... laser drive circuit.

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-76158 (JP, A) JP-A-1-220126 (JP, A) JP-A-63-3573 (JP, A) 49612 (JP, U)

Claims (2)

(57) [Claims] A digital signal processing circuit for inputting an EFM signal obtained from an optical pickup at the time of reproduction of a recordable / reproducible optical disk. At the time of recording, the recording EFM signal is input and reproduced, and the recording EFM signal is monitored. In the optical disc recording / reproducing device, the EFM signal for recording is input to the digital signal processing circuit via the mute circuit, and after switching from the reproducing state to the recording state, the EFM signal for recording is muted for a certain period of time, and then the signal processing is performed. The monitor circuit of the optical disk recording / reproducing device configured to perform. 2. An optical disk recording / reproducing apparatus capable of inputting and reproducing a recording EFM signal to a digital signal processing circuit, detecting a synchronizing signal of a subcode signal output from the digital signal processing circuit, and An optical disc recording / reproducing apparatus configured to turn off a laser circuit after recording a predetermined EFM frame from a synchronization signal of a code signal.