JP2002319168A - Deterioration detecting unit for semiconductor laser in optical recording device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect deterioration of semiconductor laser because progress in the deterioration affects normal recording and reproduction. SOLUTION: When the semiconductor laser 2 is driven at a prescribed standard output through a laser driving circuit 5 at inspecting the product in the manufacturing process, standard data is stored in a memory 12 in advance, that is data prepared from a DC voltage smoothing the light receiving output of a specific photodetector equipped in an optical head 1. Then, when the semiconductor laser 2 is driven similarly at detecting the deterioration of the semiconductor laser 2, the light receiving data obtained similarly from the DC voltage smoothing the light receiving level is compared with the standard data stored in the memory 12 by a comparing means 13. On the basis of the discrimination that the difference between the light receiving data and the standard data exceeds a prescribed value, the deterioration of the semiconductor laser 2 is detected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an apparatus for detecting deterioration of a semiconductor laser in an optical recording apparatus for detecting deterioration of a semiconductor laser of an optical head.

[0002]

2. Description of the Related Art In an optical disk recording apparatus, an optical head using a semiconductor laser (laser diode) as a light source is generally used. As such an optical disk recording apparatus, a CD (Compact Disc) format CD-R is used. (Recordable) drive and CD-RW (ReWr
Itable) drives are well known.

In the case of a CD-R drive and a CD-RW drive, recording is performed in accordance with a CD format, a semiconductor laser is driven in accordance with recording data, and pulsed laser light emitted from an optical head to a disk is used. Data recording is performed. In particular, in the case of a CD-RW drive, recording is performed by a multi-pulse recording method, and data recording is performed by a laser beam having a narrow pulse width with respect to a recording signal.

[0004]

In an optical disk recording apparatus provided with an optical head using a semiconductor laser, the deterioration of the semiconductor laser progresses in accordance with the emission time of the semiconductor laser. It cannot be performed normally.

Therefore, it is necessary to detect the deterioration of the semiconductor laser.

Further, if a disc is recorded in a state where the semiconductor laser is deteriorated, the disc may be damaged,
There is a risk of destroying already recorded data.

[0007]

SUMMARY OF THE INVENTION The present invention smoothes the received light output of a predetermined photodetector provided in an optical head when a semiconductor laser is driven at a predetermined standard output by a laser drive circuit during product inspection in a manufacturing process. The standard data obtained by converting the converted DC voltage into data is stored in a memory in advance, and the light receiving level obtained from the photodetector of the optical head when the semiconductor laser is driven at a predetermined standard output by the laser drive circuit when the deterioration of the semiconductor laser is detected. The received light data obtained by converting the DC voltage obtained by smoothing the data into the data and the standard data stored in the memory are compared by comparing means, and a determination is made that the difference between the received light data and the standard data exceeds a predetermined value. It detects the deterioration of the semiconductor laser.

[0008]

FIG. 1 is a circuit block diagram showing one embodiment of a device for detecting deterioration of a semiconductor laser in an optical recording apparatus according to the present invention.

The optical head 1 uses a laser diode 2 as a light source, and irradiates a disk 3 with a laser beam for recording and reproducing. The optical head 1 has a front monitor (not shown) for receiving a laser beam emitted from the laser diode 2 and separated on the optical path to be guided to the disk 3, and a light receiving output received by the front monitor. Is supplied to the laser driving circuit 5 via the head amplifier 4 and the laser diode 2 is driven by the laser driving circuit 5 so that the amount of light received by the front monitor is controlled to be constant. Laser light is kept constant.

The light receiving output from the front monitor is amplified by a head amplifier 4, integrated by an integrating circuit 6, level-shifted, converted into digital data by an A / D converter 7, and sent to a microcomputer 8. Is entered.

On the other hand, the reflected light of the laser light emitted from the optical head 1 and applied to the disc 3 is reflected by the optical head 1.
The received light is received by a photodetector (not shown) for receiving the reflected light, and each light output from the photodetector is amplified by the head amplifier 4. Then, an RF signal generation circuit 9 provided in the head amplifier 4 generates an RF signal which is a read signal from a disk by using a predetermined light receiving output of the photodetector.

The RF signal is converted into digital data by an A / D converter 10 and the microcomputer 8
Is input to

The microcomputer 8 comprises the optical head 1
A laser deterioration detection control means 11 for performing operation control for detecting the deterioration of the laser diode 2 and a memory 1 comprising an EEPROM in which standard data serving as a comparison reference for detecting the deterioration of the laser diode 2 are stored.
A comparison means 13 for comparing the standard data stored in the memory 12 with light reception data corresponding to the light reception output of the front monitor output from the A / D converter 7;
An input state of a disk mounting detecting unit 14 for detecting whether a disk is mounted based on digital data of a light receiving output corresponding to an RF signal output from the D converter 10 and an input key 15 for performing various operations of recording and reproduction And a key input control means 16 for generating a control signal for performing the control corresponding to the key input.

The apparatus for detecting deterioration of the semiconductor laser in the optical disk recording apparatus configured as described above is used when power is turned on, when recording is started, and when laser output is controlled to adjust the amount of laser light from the laser diode 2 to a constant value. In the above, the deterioration detection of the laser diode 2 is performed by the laser deterioration detection control means 11 according to the detection output by the disk mounting detection means 14.

The laser deterioration detection control means 11 activates the laser drive circuit 5 so that the laser diode 2 is driven by the reproduction output for reproducing the disk when the deterioration detection of the laser diode 2 is performed. Detects whether or not a disc is mounted on the basis of data of a light receiving output corresponding to an RF signal output from the A / D converter 10 at that time.

When the disc loading detecting means 14 detects that the disc is not loaded, the laser degradation detection control means 11 detects the degradation of the laser diode 2.

When the deterioration of the laser diode 2 is detected, the laser drive circuit 5 is operated so that the laser diode 2 is driven at a predetermined recording output for recording a disk. Is received by the head amplifier 4
Is supplied to the integration circuit 6 via the, and is integrated by the integration circuit 6, level-shifted, converted into digital received light data by the A / D converter 7, and input to the microcomputer 8.

The received light data input to the microcomputer 8 is compared with standard data stored in the memory 12 by the comparing means 13.

The standard data stored in the memory 12 is stored in the front of the optical head 1 when the laser diode 2 is driven by a laser drive circuit 5 at a predetermined standard output for recording a disc during product inspection in a manufacturing process. The received light output obtained from the monitor is output to the head amplifier 4,
This is the level-shifted DC voltage data obtained via the integration circuit 6 and the A / D converter 7.

Here, the light receiving output A of the front monitor of the optical head 1 obtained through the head amplifier 4 has a rectangular shape as shown in FIG. Although a pulse waveform is obtained, when the laser diode 2 is deteriorated, FIG.
As shown in FIG. 7, the pulse waveform has a rectangular shape.

For this reason, when the light receiving output A of the front monitor output from the head amplifier 4 is smoothed by the integrating circuit 6 and the level is shifted, the output B of the integrating circuit 6 becomes
The DC voltage is different between the case where the laser diode 2 shown in FIG. 2B is not deteriorated and the case where the laser diode 2 shown in FIG. 3B is deteriorated.

The standard data stored in the memory 12 is the standard data of the DC voltage corresponding to the light receiving output of the front monitor when the laser diode 2 is not deteriorated. With reference to the standard level difference V0 with respect to the level Vref (0 (V)), the detection of the standard level difference V0 and the detection data of the DC voltage corresponding to the light receiving output of the front monitor when the deterioration of the laser diode 2 is detected with respect to the reference level Vref. Compare with the level difference V1. This standard level difference V
0 and the detection level difference V1, the same reference level V
Since this is for ref, it is substantially the same as comparing the standard data and the detected data by the comparing means 13.

The comparing means 13 compares the standard data with the detected data, and determines that the difference between the detected data and the standard data is within a predetermined value which is set in advance in consideration of an allowable value of influence on recording and reproduction. In this case, the laser deterioration detection control means 11 detects that the laser diode 2 has not deteriorated, and does not limit the key input control means 16.

On the other hand, when the comparison means 13 determines that the difference between the detected data and the standard data exceeds a predetermined value, the laser deterioration detection control means 11 determines that the laser diode 2 has deteriorated. Detection is performed, the key input control means 16 is restricted, and control is performed so that various key inputs relating to recording and reproduction are not accepted.

At the same time, the laser diode 2
Notify the user that has deteriorated.

[0026]

As described above, the apparatus for detecting deterioration of a semiconductor laser in an optical recording apparatus according to the present invention can detect deterioration of a semiconductor laser, and in particular, uses the light reception output of a front monitor provided in an optical head. Since the deterioration of the semiconductor laser is detected, the detection is reliable.

Further, since the deterioration of the semiconductor laser is detected by detecting that the recording medium is not mounted, when the semiconductor laser is deteriorated, the output from the optical head is detected when the deterioration of the semiconductor laser is detected. There is no danger of damaging the recording medium by the laser light.

Since the recording operation is invalidated when it is determined that the semiconductor laser is deteriorated, the recording operation is performed when the semiconductor laser is deteriorated, so that the recording medium may not be damaged. Can be prevented.

[Brief description of the drawings]

FIG. 1 is a circuit block diagram showing one embodiment of a device for detecting deterioration of a semiconductor laser in an optical recording device according to the present invention.

FIG. 2 is a waveform diagram showing a light receiving output of a front monitor of the optical head 1 and an output of an integrating circuit 6 obtained via the head amplifier 4 of FIG.

3 is a waveform diagram showing a light receiving output of a front monitor of the optical head 1 and an output of an integrating circuit 6 obtained via the head amplifier 4 of FIG. 1 when the laser diode 2 is deteriorated.

[Explanation of symbols]

 Reference Signs List 1 optical head 2 laser diode 4 head amplifier 5 laser drive circuit 6 integration circuit 8 microcomputer 11 laser deterioration detection control means 12 memory 13 comparison means 14 disk mounting detection means 16 key input control means

Continued on the front page (72) Inventor Katsuo Yoshida 2-5-5 Keihanhondori, Moriguchi-shi, Osaka F-term in Sanyo Electric Co., Ltd. (reference) 5D119 AA33 BA01 FA05

Claims (4)

[Claims] An optical recording apparatus for recording data on a recording medium by irradiating a laser beam emitted in a pulse form from an optical head using a semiconductor laser, a laser driving circuit for driving a semiconductor laser of the optical head, When a semiconductor laser is driven by a predetermined standard output by the laser driving circuit during product inspection in a manufacturing process, standard data obtained by converting a DC voltage obtained by smoothing a light receiving level obtained from a photodetector of an optical head into data is stored in advance. Memory and
When the deterioration of the semiconductor laser is detected, the laser drive circuit drives the semiconductor laser at a predetermined standard output. When the semiconductor laser is driven at a predetermined standard output, light reception data obtained by converting a DC voltage obtained by smoothing light reception output of a predetermined photodetector provided in an optical head and the memory Comparing the standard data stored in the, the comparison means for detecting a level difference between the received light data and the standard data,
A deterioration detecting device for a semiconductor laser in an optical recording device, wherein the deterioration of the semiconductor laser is detected by judging that the level difference between the received light data and the standard data exceeds a predetermined value. 2. The optical recording apparatus according to claim 1, wherein the photodetector of the optical head is a front monitor that receives a laser beam emitted from a semiconductor laser irradiating the recording medium and guided to the recording medium. For detecting deterioration of semiconductor lasers in Japan. 3. The apparatus for detecting deterioration of a semiconductor laser in an optical recording apparatus according to claim 2, wherein the detection of deterioration of the semiconductor laser is performed by detecting that a recording medium is not mounted. 4. The apparatus for detecting deterioration of a semiconductor laser in an optical recording apparatus according to claim 1, wherein the recording operation is invalidated when it is determined that the semiconductor laser has deteriorated.