JPH038131A - Optical data storing and reproducing device - Google Patents

Abstract

PURPOSE:To prevent the excessive light emission of semiconductor laser at the time of switching by lengthening the light emitting time of the semiconductor laser and reducing the output of a comparator before switching a record-hold mode to a reproducing mode. CONSTITUTION:A DC signal is generated until the switching is performed instead of a dummy signal of an information signal b from an information signal generation circuit 14 before switching the record-hold mode to the reproducing mode. Then, the semiconductor laser 3 emits light for a long term, which is received by a photodetector 11, and after it is converted into an electric current and a voltage, the (+) input of the comparator 5 becomes low and the output of the comparator 5 can be reduced until the switching is performed. Thus, the excessive light emission of the semiconductor laser is prevented at the time of switching the record-hold mode to the reproducing mode.

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 an optical disc.

An example of the above-mentioned conventional optical data storage/reproduction device will be described with reference to conventional technical drawings.

3 and 4 are a circuit diagram and a timing chart of a semiconductor laser drive circuit of a conventional optical data storage/reproduction device.

In FIG. 3, 1 is an input terminal for a sample/hold switch signal B, 2 is an information signal generation circuit, 3 is a semiconductor laser, 4 is a hold circuit, 6 is a comparator, 6 is a buffer circuit, 7 to 10 1 is an analog switch, 11 is a photodetector built into a semiconductor laser, 12 is a Vi reference voltage generation circuit, 1 is
3 is an input terminal C for a reproduction/recording switching signal.

a is a sample hold switching signal, b is an information signal, C
is a reproduction/record switching signal, and d is an optical output of the semiconductor laser 3.

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

First, in the playback mode, the sample bold switching signal a is at a low level, and the analog switch 7.8 is on.
9 is off. The analog switch 10 provides the comparator 5 with a reproduction power reference voltage from the reference voltage generation circuit 12. At this time, the optical output d from the semiconductor laser 3 is DC light emission.

Further, a current flows through the photodetector 11 in proportion to the optical output d,
The current is converted into voltage, and a comparator 5 applies servo to keep the optical output constant.

In the recording servo mode, the analog switch 10 applies a recording power reference voltage from the reference voltage generation circuit 12 to the comparator 6. At this time, since the information signal bKVi and the dummy signal are input, the optical output d from the semiconductor laser 3 is modulated by the dummy signal, and the servo is also lost as described above. In the recording hold mode, the sample hold switching signal a becomes high level, the analog switch 7.8 is turned off, and the data signal is input as the information signal bK, so the optical output d of the semiconductor laser 3 is modulated by the data signal. san
, its amplitude is held from the time of recording servo mode.

Problems to be Solved by the Invention However, in the conventional configuration as described above, as shown in FIG. However, there were problems in that the optical disk was destroyed and the semiconductor laser deteriorated. When changing from the recording hold mode to the playback mode, the dummy signal is emitted for a certain period of time (T2 to T
3) This is caused by stopping.

In view of the above-mentioned problems, an object of the present invention is to provide an optical data storage/reproduction device that can prevent excessive light emission of a semiconductor laser when switching from recording hold mode to reproduction mode (T3). It is.

Means for Solving the Problems In order to solve the above-mentioned problems, the optical data storage/reproduction device of the present invention switches the semiconductor laser to the sample hold switching signal shortly before switching from the recording hold mode to the playback mode. This device is configured to prevent the semiconductor laser from emitting excessive light by controlling the light emitting time to be longer.

An advantage of the invention is that with the above configuration, the output of the comparator can be lowered when switching from the recording hold mode to the reproduction mode, thereby making it possible to prevent the semiconductor laser from emitting excessive light.

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

1 and 2 are a circuit diagram and a timing chart of a semiconductor laser drive circuit of an optical data storage/reproduction device according to the present invention. In FIGS. 3 and 4, reference numeral 14 denotes an information signal generation circuit, bB information G, and 1. The other parts are the same as the conventional ones.

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

This device is characterized in that, from T1 slightly before T2 when switching from the recording hold mode to the playback mode, for example, a DC signal up to 2 is generated instead of the dummy signal of the information signal.

This causes the semiconductor laser 3 to emit light for a long period of time. As a result, after the light is received by the photodetector 3 and converted into current and voltage, the power of the comparator 6 becomes low, and 71 to 72
The output of the comparator 5 in between is lowered to prevent the semiconductor laser 3 from emitting excessive light at 73.

As described above, according to this embodiment, excessive light emission (T3) of the semiconductor laser 3 can be prevented when switching from the recording hold mode to the reproduction mode.

In the embodiment, a DC signal is used instead of the dummy signal of the information signal, but the duty of the dummy signal may be changed instead of the DC signal to cause the semiconductor laser 3 to emit light for a long period of time.

Effects of the Invention As described above, according to the present invention, the output sound of the comparator can be lowered when switching from the recording hold mode to the playback mode, thereby preventing the semiconductor device from emitting excessive light.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a semiconductor laser drive circuit of an optical data storage/reproduction device according to an embodiment of the present invention. FIG. 2 is a timing chart thereof, FIG. 3 is a circuit diagram of a conventional example, and FIG. 4 is a typing chart thereof. 1... Input terminal of sample hold switching signal hole, 14... Information signal generation circuit, 3...
...Semiconductor laser, 4...Hold circuit, 6.
... Comparator, 6-... Buffer circuit, 7-10.
...Analog switch, 11...Photodetector, 12...Reference voltage generation circuit, 13...
Input terminal for recording/playback switching signal C.

Claims (1)

[Claims] It has means for recording and reproducing data on an optical disk using a laser light source, a recording servo mode in which the output of the laser light source is kept constant during recording, and a recording hold mode in which the output of the laser light source in the recording servo mode is kept constant. and means for generating a sample hold switching signal and a playback/record switching signal for switching between these two modes, and when switching from the record hold mode to the playback mode,
An optical data storage/reproduction device characterized by comprising: means for controlling the emission time of the laser light source to be elongated before switching the sample hold switching signal.