JPH038133A - Optical data storing and reproducing device - Google Patents

Abstract

PURPOSE:To reduce the output power of a laser light source less than the allowable light output of laser and to prevent the deterioration of the light source and the deterioration of a recording medium by adding a dummy signal for a fixed term to an information signal for modulating the laser under a recording mode. CONSTITUTION:At the time of recording, a reproducing and recording switching signal (c) becomes high level, and a recording reference voltage is given to a comparator 15. And the laser is modulated by the dummy signal outputted from the information signal (b). And an electric current flows in a photodetector 24 in proportion to the light output pulse of the laser and the peak-hold detection of the laser output is performed in a peak-hold circuit 26 and servo control is executed by the comparator 15 so that the light output may be fixed. When the laser output attains a recording power, the light output of the laser light source 13 is held as the recording power by a hold circuit 14. Thus, the laser output is reduced less than the allowable light output of the laser light source and the deterioration of the laser light source and the recording medium are prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an optical data storage/reproduction device for optically recording and reproducing data on a disk.

Conventional technology Laser drive circuits in optical data storage and reproducing devices are
For example, it is configured as shown in FIG. here,
1 is an input terminal for a sample hold (S/H) switching signal a, 2 is an input terminal for an information signal, 3 is a laser light source, 4
is a hold circuit, 5 is a comparator, 6 is a buffer circuit, 7~
10 is an analog switch, 11 is a photodetector, 12 is a reference voltage generation circuit, and 13 is an input terminal for a recording/reproduction switching signal C.

FIG. 4 is a timing chart of the laser drive circuit and a light output diagram of the laser light source 3.

The operation of the conventional optical data storage/reproduction device configured as described above will be explained below.

First, during playback, the S/H switching signal a is at a low level,
Analog switch 7.8 is on and 9 is off. Analog switch 10 provides a reproduction reference voltage to the comparator. At this time, the light output from the laser light source 3 becomes a DC light emission output. A current flows through the photodetector 11 in proportion to the optical output, and a comparator 5 performs power servo of the laser light source to keep the optical output constant.

At the time of recording, first, the analog switch 10 is used to switch to the recording reference voltage. As a result, the optical output from the laser light source 3 reaches the recording power. Thereafter, the S/H switching signal a becomes high level, the analog switch 7.8 is turned off, and the current flowing through the laser light source 3 corresponding to the recording power is held. Further, the light output from the laser light source 3 is modulated by the information signal. As described above, power servo is applied until the laser light source 3 reaches the recording power during reproduction and recording, and thereafter enters a hold state and modulates the optical output.

Problems to be Solved by the Invention However, in the conventional configuration as described above, the laser beam is used for a long period of time (approximately 5 to 10 μ5) in the recording mode.
The laser emits light and has a recording power, and depending on the recording power value, exceeds the permissible optical output (CW) of the laser light source, resulting in DC recording on the recording medium, which causes the problem of deterioration of the recording medium or the laser light source. Was.

SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to provide an optical data recording/reproducing apparatus having a function of preventing deterioration of a laser light source and a recording medium in recording mode.

Means for Solving the Problems In order to solve the above-mentioned problems, the optical data storage/reproduction device of the present invention uses a constant information signal to modulate the laser in the recording mode when recording on an optical disc using a laser light source. It has a configuration in which a dummy signal of a predetermined frequency is added for a period.

According to the above configuration, the present invention can make the output power of the laser light source less than the laser allowable optical output (CW) by adding a dummy signal of a predetermined frequency for a certain period of time to the information signal that modulates the laser in the recording mode. This makes it possible to prevent deterioration of the laser light source and the recording medium.

Embodiment Hereinafter, an optical data storage/reproduction device according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows a laser drive circuit in an optical data storage/reproduction device according to an embodiment of the present invention.

In FIG. 1, 11 is an input terminal for a reproduction/recording switching signal C, 12 is an input terminal for an information signal, 13 is a laser light source,
14 is a sample hold circuit.

15 is a comparator, 16 is a buffer circuit, 17 to 21 are analog switches, 22 is a base 1 voltage generation circuit, 23 is S/H
24 is an input terminal for a switching signal a, 24 is a photodetector, 25 is an input terminal for a peak hold gate signal d, and 26 is a peak hold circuit.

The operation of the optical data storage/reproduction device constructed as described above will be explained below with reference to FIGS. 1 and 2.

First, FIG. 2 shows a timing chart and the optical output of the laser light source 13 of this embodiment.

During reproduction, the reproduction/recording switching signal C is at a low level, and the analog switch 21 supplies the reproduction reference voltage to the comparator. The S/H switching signal a is at a low level, the analog switches 17 and 20 are on, and the analog switches 19 are off. The peak gate signal d is at a high level and the analog switch 18
is off.

At this time, the optical output from the laser light source 13 becomes a DC emission output, a current flows through the photodetector 24 in proportion to the optical output, and a servo is applied by the comparator 15 so that the optical output is constant.

During recording, the reproduction/recording switching signal C becomes high level, and the recording reference voltage is applied to the comparator 5. The laser is modulated by a dummy signal output from the information signal. In addition, the peak hold gate signal d becomes low level, the analog switch 18 is turned on and the analog switch 20 is turned off, current flows through the photodetector 24 in proportion to the optical output pulse of the laser, and the peak hold circuit 26 outputs a dummy signal. Performs peak hold detection of the laser output modulated by comparator 1.
5, servo is applied so that the optical output is constant.

After the laser output modulated by the dummy signal reaches the target recording power, the S/H switching signal a is set to a high level,
Further, by setting the peak hold gate signal d to a high level, analog switches 17 and 18 are turned off and analog switches 19 are turned on. Analog switch 19 prevents comparator 15 from becoming saturated during record hold mode. The recording current source voltage is held by the hold circuit 14, and the optical output of the laser light source 13 is maintained at the recording power.

As described above, according to this embodiment, by inserting a dummy signal into the information signal that modulates the laser for a certain period in the recording servo mode, the laser output is reduced to less than the allowable optical output (CW>) of the laser light source. Therefore, deterioration of the laser light source and the recording medium can be prevented.

In the above embodiment, the photodetector 24 is used, but the photodetector may be a photodetector inside the laser package.

Further, although the peak hold circuit 26 is used in the above embodiment, the peak hold circuit may be an average value circuit.

Furthermore, the dummy signal used is not limited to a specific frequency or pulse width.

Effects of the Invention As described above, according to the present invention, by adding a dummy signal of a predetermined frequency to the information signal that modulates the laser for a certain period of time at the start of recording in the recording mode, deterioration of the laser light source and damage to the recording medium can be prevented. This makes it possible to realize an excellent optical data storage/reproduction device that can prevent deterioration.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a laser drive circuit used in an optical data storage/reproduction device according to an embodiment of the present invention, FIG. 2 is a timing chart and an optical output diagram of a laser light source 13 of the same embodiment, and FIG. FIG. 4 is a circuit diagram of a laser drive circuit in a conventional optical data storage/reproduction device. FIG. 4 is a timing chart of a laser drive circuit and an optical output diagram of a laser light source 3 in a conventional optical data storage/reproduction device. 11...Input terminal for playback/recording switching signal C, 1
2... Information signal input terminal, 13...
・Laser light source, 14...Hold circuit, 15.
...Comparator, 16...Buffer circuit, 1
7-21...Analog switch, 22...
...Reference voltage generation circuit, 23...S/'H
Input terminal for switching signal a, 24...photodetector,
25...Input terminal for peak hold gate signal d, 26...Peak hold circuit, a...
...S/H switching signal, b...information signal, C
...Reproduction/recording switching signal, d...Peak hold gate signal, e...Laser light source 1
3 light output.

Claims (1)

[Claims] means for recording and reproducing data on an optical disk using a laser light source, means for adding a dummy signal of a predetermined frequency immediately before an information signal that modulates the laser light source for a certain period of time at the start of recording in a recording mode, and the dummy signal and means for operating the power servo circuit for the laser beam.