JPH1064098A - Optical information recording and reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform a correct measurement which is not affected by random emissions due to information bits by measuring the characteristic of the relation between the driving current and the outgoing light quantity of a laser in the same condition as that at the time of recording or erasing data. SOLUTION: A control circuit 11 sets the leading address Addr1 of a determined area for measurement in an address detecting circuit 10 and moves a light beam to a target address Addr1 by driving an optical head 3 with a servo circuit 12. Then, when an address coincident signal is outputted and this signal is detected, a laser driving circuit 14 controls a driving current so that a laser light quantity becomes a fixed light quantity by minitoring the laser light quantity. Then, target light quantities are set to, for example, 5 steps and respective driving currents are stored in a memory. Then, the characteristic of the realation between the driving current and the outgoing light quantity of the laser is measured in the same condition as that at the time of recording and erasing of data. Thus, the correct measurement which is not affected by the random emissions due to the information bits is performed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an optical information recording / reproducing apparatus for recording, reproducing and / or erasing information on a recording medium by irradiating the recording medium with light from a light source.

[0002]

2. Description of the Related Art Laser light quantity control devices are used in various technical fields, but are particularly often used in optical information recording / reproducing devices for irradiating a recording medium with light to record, reproduce, and / or erase information. Have been.

Conventionally, a laser light source is usually used as a light source of the optical recording / reproducing apparatus because a beam spot can be narrowed down to a very small size. As such a device, the present applicant has proposed Japanese Patent Application No. 63-44226. This has a control loop means for detecting the irradiation light of the light source, and increasing or decreasing the irradiation light of the light source in comparison with the reference light amount,
In an optical information recording / reproducing apparatus for recording, reproducing and / or erasing information on a recording medium by irradiating the recording medium with light from a light source, when recording or erasing, the amount of irradiation at the time of reproduction immediately before the recording or erasing is reduced. This is an optical information recording / reproducing apparatus having means for setting an irradiation light amount of a light source at the time of recording or erasing by adding a predetermined signal for recording or erasing to a control signal to be generated.

[0004]

In such a configuration, a predetermined signal for recording or erasing must be stored in advance. However, the characteristics of the relationship between the drive current of the laser and the light emission output change in the characteristics when the temperature of the laser changes. Also, as the life of the laser approaches, the slope of the characteristics changes, and the linearity also worsens. For this,
If a predetermined signal to be added at the time of recording or erasing is determined at the time of product shipment, an erroneous signal will be added at the time of recording or erasing if the characteristics change later.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to further improve the apparatus of the above-mentioned prior application, and to control the amount of laser light accurately even if the characteristics of the laser change from the time of product shipment. An object of the present invention is to provide an information recording / reproducing device.

The object of the present invention is to provide a laser light source, means for supplying a current for driving the light source, and means for monitoring the output of laser light emitted from the light source, and irradiating the laser light onto an optical recording medium. In the optical information recording / reproducing apparatus performing at least one operation of recording, reproducing, or erasing information by doing, prior to the operation, the information on the optical recording medium can be recorded, reproduced, or erased, and A laser drive unit configured to measure a relationship between a drive current and an optical output of the laser light source while irradiating a laser beam to an area where information is not recorded, and to set a drive current during the operation based on the measurement result; This is achieved by:

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an optical information recording / reproducing apparatus according to the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of an embodiment of the optical information recording / reproducing apparatus of the present invention. FIG.
FIG. 3 is a view showing a state of measurement of the laser light amount in the apparatus shown in FIG. 1, and FIGS. 3 and 4 are flowcharts showing a process of this measurement.

In FIG. 1, reference numeral 1 denotes an information recording medium disk which is rotated by a motor 2. Light emitted from the semiconductor laser 4 is focused on the disk 1 by the objective lens 5. The light reflected from the disk 1 passes through the objective lens 5 again, is photoelectrically converted by the sensor 6, and is amplified by the preamplifier 7. Here, the focus error signal, the track shift signal, and the reproduction information signal are divided. The reproduction information signal is digitized by the binarization circuit 8, becomes a data signal by the demodulation circuit 9, and is transmitted to the host device. The recording data signal from the host device is input to the modulation circuit 13 and the laser drive circuit 1
4 to drive the laser 4. The track shift signal and the focus error signal output from the preamplifier 7 are input to the servo circuit 12, and based on this, the focus of the optical head 3,
Track deviation is controlled. Reference numeral 11 denotes a control device of the information recording / reproducing device, which controls the present device in accordance with an instruction from a higher-level device.
An address detection circuit 10 detects an address of a beam position on a disk from an output of the demodulation circuit 9.

The operation of the apparatus shown in FIG. 1 will be described with reference to the flowchart of FIG. When the apparatus is powered on, it detects whether or not a disk is mounted on the apparatus (not shown) (step 102). When the disc is not mounted, the detection of whether the disc is inserted is continued (step 110), and after the disc insertion is detected, the loading operation of the disc (step 111) is performed. When the disk is loaded (Step 102), the rotation of the disk is started by the motor 2, and when the rotation reaches the steady rotation, a command is issued to the laser drive circuit 14 to turn on the laser with the reproduction light amount and the servo circuit 12 Focus control and tracking control are performed (step 103). Thereafter, the characteristics of the laser, which will be described with reference to FIG. 4, are measured. The temperature of the laser at this time is measured and set to T _O (step 104). When the measurement is completed, the respective operations are performed according to the presence / absence of the reproduction, recording, and erasure instructions (step 105) (step 10).
6) It is determined by a temperature detection circuit (not shown) whether or not the temperature of the laser has changed by a predetermined temperature T _D (here, 5 ° C.) or more from the temperature at which the characteristics of the laser were previously measured (step 107). If there is a change of T _D or more, the laser characteristics are measured again. If there is no temperature change, it is determined whether or not there is an instruction to eject the disc (step 108). If there is no instruction to eject the disc, the apparatus waits for an instruction to reproduce, record, or erase again. If there is a discharge instruction, the tracking control and the focus control by the servo circuit 12 are stopped, and a command is issued to the laser drive circuit 14 to turn off the laser. Then, the rotation of the disk is stopped, and the ejection operation is performed (step 109). Thereafter, it waits for the disk to be loaded again (step 110).

In the measurement of the characteristics of the laser, information such as address data capable of recording and reproducing data is recorded in a predetermined area of the disk while focus control and tracking control are being performed. Do in the part that is not. This is to ensure that the amount of return light to the laser is the same as that for actually recording and erasing data. When the amount of return light to the laser changes, the efficiency of laser emission changes, and accurate measurement of characteristics cannot be performed.

This area is an area in which data is not actually recorded, and the address is always checked by a host computer or a controller.

The measurement of the characteristics of the laser will be described with reference to the flow chart of FIG. 4 and FIGS. 1 and 2. When the measurement is started (step 201), first, the control circuit 11 sets the start address Addr1 of the determined measurement area in the address detection circuit 10, and drives the optical head 3 by the servo circuit 12, The light beam is directed to the target address Addr1.
(Step 202). Next, n of the measurement step calculation register is set to 1 (step 203), and the process waits until the address becomes Addr1. In the signal reproduction of the header portion of the H _1, if the address is the Addr1, address match signal is output from the address detection circuit 10, if this is detected (step 204), in FIG. 2t _1,
The control target of the control circuit of the laser light intensity and light output of P ₁ (step 205). The laser control circuit 14 monitors the amount of laser light and controls the drive current so that the amount of light becomes constant. This circuit responds, at time t _2, the light output is P _1. At this time, by moving the big time timer than t ₁ -t ₂ (step 206), the amount of light is sufficiently stable, and, at time t ₃ before the address area of the next sector, the drive current memory (Step 207). This portion is the data area D _1. Thereafter, n is incremented by one (step 209).
Here, n _max is set to 5, the target light quantity is set to 5 levels,
The drive current at each time is stored in the memory.

The range of the light output in the five steps satisfies the range of the light output required when the temperature of the disk and the relative speed between the medium and the spot at the recording position change. The setting of the target value is sequentially changed from a low light amount to a high light amount. When the value of In becomes the maximum value that the drive circuit can drive, it means that the life of the laser is near,
There is a possibility that the required amount of light may not be obtained, and it is displayed that an error has occurred in the laser or transmitted to the host device to prompt the user to replace the laser.

[0015] Thus, with respect to the target output from P ₁ to P _5, to obtain a drive current. By driving with a drive current corresponding to the required amount of erasing light or recording light from the value obtained at this measurement point, a target light output is obtained. When the light quantity between the measurement points is required, the drive current is determined by approximating a straight line.

If the current to be measured is measured as the current added to the drive current corresponding to the reproduced light quantity when the APC operation immediately before the measurement is performed, the above-mentioned Japanese Patent Application No.
The predetermined current described in Japanese Patent No. 44226 can be used.

Further, a measured value can be used as an initial current when the APC operation is performed during recording and erasing.

In the above embodiment, the characteristics of the laser were measured by DC lighting. However, the laser light amount at the time of recording is pulse lighting, and a peak light amount may require a larger light amount than the light amount at the time of erasing. When measuring the driving current at this time, the laser can be modulated in a manner different from pulse lighting. For DC lighting and pulse lighting, for lasers that have the maximum rating of the laser output,
The rating during pulse lighting is higher. Therefore, in the measurement of the characteristics performed by pulse lighting, a wider range of measurement can be performed than the measurement performed by DC lighting.

In the case of performing measurement by pulse lighting, if the frequency characteristic of the circuit for monitoring the amount of light emitted from the APC loop is lower than the pulse frequency, the frequency may be converted into an amount corresponding to a predetermined pulse lighting duty ratio. Good.

When measuring by pulse lighting, when lighting the header to confirm the address, it is necessary to use DC lighting. It is desirable that the light amount at this time be a low light amount at the time of reproduction. Also when performing measurement with DC lighting, the header portion can be set to the amount of light during reproduction.

[0021]

According to the optical information recording / reproducing apparatus as described above, the characteristics of the relationship between the drive current of the laser and the amount of emitted light can be measured under the same conditions as when recording or erasing data. . In particular, since the measurement is performed using an area where information such as address data is not recorded,
Accurate measurement that is not affected by light emission by information pits is possible. Then, by driving the laser at the time of recording or erasing based on the current measured here, it is possible to irradiate the medium with the optimum amount of light to perform recording or erasing.

[Brief description of the drawings]

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

FIG. 2 is a view for explaining how laser light quantity is adjusted in the apparatus shown in FIG. 1;

FIG. 3 is a flowchart showing an operation process of the apparatus shown in FIG. 1;

FIG. 4 is a flowchart showing an operation process of the apparatus shown in FIG. 1;

[Explanation of symbols]

 Reference Signs List 1 disc 2 motor 3 optical head 4 semiconductor laser 5 objective lens 6 sensor 7 preamplifier 8 binarization circuit 9 demodulation circuit 10 address detection circuit 11 control circuit 12 servo circuit 13 modulation circuit 14 laser drive circuit

Claims (1)

[Claims] 1. A laser light source, means for supplying a current for driving the light source, and means for monitoring the output of laser light emitted from the light source, wherein the information is obtained by irradiating the laser light onto an optical recording medium. In an optical information recording / reproducing apparatus that performs at least one of recording, reproduction, and erasing operations, prior to the operation, recording information on the optical recording medium,
The relationship between the drive current and the light output of the laser light source is measured while irradiating a laser beam to an area where reproduction or erasing is possible and information is not recorded, and the drive current during the operation is determined based on the measurement result. An optical information recording / reproducing apparatus, comprising: a laser driving unit for setting the optical information.