WO2001063603A1

WO2001063603A1 - Disk drive

Info

Publication number: WO2001063603A1
Application number: PCT/JP2001/001277
Authority: WO
Inventors: Koichi Tada; Toshihide Hamaguchi; Hideaki Yano
Original assignee: Sanyo Electric Co., Ltd.
Priority date: 2000-02-23
Filing date: 2001-02-21
Publication date: 2001-08-30
Also published as: JP2001236649A

Abstract

A disk drive includes a temperature sensor (24) arranged near an optical pickup (12). The temperature sensor detects the temperature of the surroundings of the optical pickup. The values of laser power and gain corresponding to the detected temperature are read from a table (48) recorded in a ROM (36). The value of laser power is set to a laser drive (50), and the value of gain is given to a tracking actuator signal and a focal actuator signal. Low laser power is set at high temperature while high laser power is set at low temperature.

Description

Specification

Disk unit technical field

The present invention relates to an optical disk device, and particularly to, for example, a recording surface of an optical disk.

—The present invention relates to an optical disk device that irradiates the light and records and reproduces a signal.

Background art

In this type of optical disk device, an optical pickup is used for recording an image signal on a magneto-optical disk. If the operation continues in an environment where the temperature around the optical pickup is high, the life of the semiconductor laser is shortened. In order to prevent the shortening of the life, the laser power of the laser light output from the semiconductor laser is reduced as the peripheral temperature increases.

When the laser power decreases, the output of the control signal of the servo system also decreases, and the operation of the support system becomes unstable. As a result, there has been a problem that read errors and write errors frequently occur during read / write.

Summary of the Invention

SUMMARY OF THE INVENTION Therefore, a main object of the present invention is to provide an optical disk device that can operate stably even when the ambient temperature of an optical pickup is high. An optical disk device according to the present invention irradiates a laser beam output from a semiconductor laser to a recording surface of an optical disk through an optical lens, and includes: a detection device for detecting an ambient temperature of the semiconductor laser; Means; laser power reduction means for reducing the laser power value of the semiconductor laser as the ambient temperature detected by the detection means increases; generation means for generating a servo control signal based on the reflected light of the laser light on the recording surface; A displacement means for displacing the optical lens in response to a control signal; a gain table in which a plurality of temperature values and a servo control gain that increases as the temperature value increases are stored in association with each other; Read the servo control gain corresponding to the temperature from the gain table Read the servo control gain And servo control gain setting means for setting the servo control gain read by the servo control gain reading means in the generation means. In the present invention, the laser power of the laser beam output from the semiconductor laser and the servo control gain added to the servo control signal are changed according to the change in the ambient temperature of the semiconductor laser. First, the detecting means detects the ambient temperature of the semiconductor laser. The laser power reduction means reduces the laser power of the semiconductor laser if the ambient temperature detected by the detection means is high, and prevents the temperature of the semiconductor laser from further increasing. In the gain table, a plurality of temperature values and a support control gain corresponding to this temperature value are stored in association with each other, and a higher temperature value corresponds to a larger support control gain. The servo control gain readout means reads out the support control gain corresponding to the ambient temperature detected by the detection means from the gain table, and the support gain setting means sets the readout servo control gain in the generation means. The generating means generates a servo control signal, and further adds the set servo control gain to the servo control signal and outputs the signal. The displacement means displaces the position of the optical lens in response to the servo control signal output by the generation means. As a result, even if the laser power of the semiconductor laser is reduced when the ambient temperature rises, a support control signal optimal for the lowered laser power is generated, and the optical control signal is generated in response to the servo control signal. The position of the lens is controlled. Therefore, even if the peripheral temperature of the semiconductor laser rises, it can be operated stably.

In another preferred embodiment of the present invention, the servo gain signal includes a focus control signal for performing focus control of the optical lens and a tracking signal for performing tracking control, and the gain table further includes a plurality of temperatures. The focus control signal and the tracking control signal which increase as the value and the temperature value increase are stored. Therefore, even when the peripheral temperature of the semiconductor laser changes, such as a high temperature, focus control and tracking control of the optical lens can be stably performed.

In another preferred embodiment of the present invention, the laser power value set for the semiconductor laser is determined with reference to a table provided in advance. That is, first, a laser power value table is prepared in which a plurality of temperature values and a laser power value corresponding to the temperature value are stored in association with each other. Each of the plurality of temperature values is equal to each of the temperature values of the servo gain table. Also, the laser power value increases as the corresponding temperature value increases. And become smaller. Laser power value reading means reads a laser power value corresponding to the ambient temperature from the laser power value table. Laser power reducing means changes the laser power of the semiconductor laser to the laser power value read by the laser power value reading means. As described above, the laser power value to be changed is held in a table corresponding to the temperature value, and the laser power value is determined based on this table. Therefore, the laser temperature value of the laser power is shifted and corrected to thereby correct the laser power value. Unlike the case of determining the value, it is possible to set an optimum laser power value at a predetermined temperature value. In addition, since the temperature value and the number corresponding to the laser power value are equal to the temperature number and the value corresponding to the support control gain, the optimum servo control gain for the laser power value is accurately and quickly determined. be able to. Therefore, even when the ambient temperature changes, the focus control and the tracking control can be appropriately performed, and the disk device can be stably operated.

According to the present invention, the laser power value of the laser light output from the semiconductor laser is changed according to the peripheral temperature of the semiconductor laser to prevent the temperature of the semiconductor laser from rising, and the changed ambient temperature, that is, The optimum control gain for the selected laser power value is added to the control signal. Therefore, even if the peripheral temperature of the semiconductor laser rises, the optical disc device can be operated stably by performing appropriate servo control. The above and other objects, features, and advantages of the present invention will become more apparent from the following detailed description of embodiments with reference to the drawings.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a block diagram showing one embodiment of the present invention;

FIG. 2 is an illustrative view showing a change in laser power with respect to a temperature change, FIG. 2 (A) is a graph showing a change in a reproduction laser power, and FIG. 2 (B) is a graph showing a change in a recording laser power;

Figure 3 is an illustrative view showing a table associating temperature with reproduction laser power, recording laser power, and gain;

Figure 4 is an illustrative view showing the change in the response characteristics of the tracking servo system and the focus servo system to a temperature change;

FIG. 5 is an illustrative view showing a part of the operation of the embodiment in FIG. 1; and FIG. 6 is an illustrative view showing another portion of the operation of the embodiment in FIG.

BEST MODE FOR CARRYING OUT THE INVENTION

Referring to FIG. 1, a disk device 10 of this embodiment includes an optical pickup 12. The optical pickup 12 is connected to the thread module 38 by a rack gear and a pinion gear, and is driven in the radial direction of the optical disk 60 by driving these gears. The thread module 38 is controlled by a thread control signal provided from a digital signal processor (DSP) 32 through a pulse width modulation (PWM) driver 42a. The optical pickup 12 includes an optical lens (objective lens) 16, which is supported by a tracking actuator 14 and a force actuator 18. The position of the optical lens 16 in the optical axis direction is controlled by a focus function 14, and the position of the optical lens 16 in the radial direction of the optical disc 60 is controlled by a tracking function. . The tracking work 14 and the focus work 18 are based on the tracking work signal and the focus work provided from the DSP 32 through the PWM driver 42 b and the PWM driver 42 c. It operates according to the heater signal.

Laser light oscillated from a laser diode (semiconductor laser) 20 provided inside the optical pickup 12 is converged by the objective lens 14 and irradiated on the recording / reproducing surface of the optical disk 60. Thus, a desired signal is written to the optical disc 60, and a desired signal is reproduced from the optical disc 60.

The laser light (reflected light) reflected by the recording Z reproducing surface of the optical disk passes through the same objective lens 16 and enters the photodetector 22. The sensor signal output from the photodetector 22 is input to the TE signal detection circuit 28 and the FE signal detection circuit 30 through the servo amplifier 26. The TE signal detection circuit 28 detects the TE signal (tracking error signal), and the FE signal detection circuit 30 detects the FE signal (focus error signal). The TE signal and FE signal respectively detected by the TE signal detection circuit 28 and the FE signal detection circuit 30 are sent to the AZD converter 40a and the AZD converter 40b provided in the DSP 32. Each given.

The optical disk 60 is mounted on a turntable 44 and a turn tape is provided. The screw 44 is connected to a spindle motor 40 via a shaft 42. The spindle motor 40 is rotated by a motor control signal provided from the DSP 32 through the PWM driver 42d. When the spindle motor 40 rotates, the rotation is transmitted to the table 44 via the shaft 42, and the turntable 44, that is, the optical disk 60 rotates. The spindle motor 40 generates an FG pulse related to the rotation speed, and the FG pulse is given to the AZD converter 40 c of the DSP 32.

In this way, the TE signal, the FE signal, and the FG signal provided to the AZD converters 40a, 40b, 40c are converted to digital signals and then provided to the DSP 3732a. 03 Core 32 & executes the tracking support processing based on the TE signal, executes the focus support processing based on the FE signal, and further executes the spindle support processing based on the FG signal.

The tracking servo process generates a thread control signal and a tracking work control signal. The thread control signal and the tracking work control signal are converted into PWM signals by the PWM drivers 42a and 42b, and supplied to the thread control 38 and the tracking work 14. The focus control signal generated by the focus support processing is converted into a PWM signal by the PWM dry line 42b and supplied to the focus control 18. Further, a spindle servo motor control signal is generated by the spindle support process, converted into a PWM signal by the PWM driver 42 d, and given to the spindle motor 40.

Thus, a tracking support system is formed by the TE signal detection circuit 28, the DSP 32, the tracking function unit 14 and the thread module 38. The tracking servo system appropriately controls the tracking of the optical lens 16 based on the TE signal. Further, a focus servo system is formed by the FE signal detection circuit 30, the DSP 32, and the focus actuator 18. The focus support system appropriately controls the focus of the optical lens 16 based on the FE signal. Further, a spindle servo system is formed by the spindle motor 40 and the DSP 28, and the spindle motor 40, that is, the rotation of the optical disk 38 is controlled based on the FG signal. Rolling is properly controlled. As a result, the laser beam oscillated from the laser diode 20 is applied to a desired position on the recording / reproducing surface of the optical disc 60, whereby a desired signal is appropriately recorded on the optical disc 60 and reproduced. You.

Recording of information on the optical disk 60 Z reproduction is performed properly by the functions of the tracking system, focus servo system, and spindle servo system. However, the tracking servo system and the focus servo system perform control based on the TE signal and the FE signal obtained from the reflected light of the laser light. Therefore, the stability of the operation of the optical disk device 10 depends on the stability of the laser light oscillated from the laser diode 20.

The life of the laser diode 20 is shortened if laser light oscillation is continued in a high temperature state. Therefore, when the temperature around the laser diode 20 becomes high, it is necessary to lower the laser power value of the oscillating laser light to prevent the temperature from further rising. However, as described above, if the laser beam changes due to the ambient temperature, the tracking servo process and the focus servo process become unstable, and the operation of the optical disc device 10 becomes unstable.

Therefore, in this embodiment, the laser power value of the oscillating laser light is changed in accordance with the changing ambient temperature of the laser diode 20, and the focus laser is appropriately adjusted at the changed ambient temperature, that is, at the changed laser power value. The gain (Gain) that can perform the zooming process and the tracking process is added to the focus control signal and the tracking control signal.

As shown in FIG. 1, a temperature sensor 24 is arranged around the optical pickup 12. The temperature sensor 24 generates a temperature signal corresponding to the detected temperature and supplies the temperature signal to the microcomputer 34. For convenience of illustration, FIG. 1 shows a temperature sensor 24 outside the optical pickup 12, but in actuality, the temperature sensor 24 is a mouthpiece mechanism, a pickup feed mechanism, a pickup mechanism, a rotation mechanism, and the like. And a drive mechanism (not shown). Therefore, the temperature sensor 24 generates a temperature signal corresponding to the temperature of the room in which the drive mechanism is sealed and supplies the temperature signal to the microcomputer 34. The microcomputer 34 detects the temperature based on the temperature signal. On the other hand, the ROM 36 that can be read from the microcomputer 34 is detected by the microcomputer 34. Temperature, laser power value, focus support system gain and tracking

—Table 48 that stores each of the gains of the control system is stored. Details of this table 48 will be described later. The microcomputer 34 refers to the table 48 using the detected temperature value as a key, and determines each of the laser power value, the focus control system gain, and the tracking servo system gain corresponding to the temperature. Then, these values are given to DSP 32.

The laser light oscillated from the laser diode ₂₀ greatly differs between when recording information and when reproducing information. Therefore, a laser power value corresponding to the temperature is required for each of the reproducing laser and the recording laser. Also, the temperature of the laser diode 20 increases as the laser power increases. Therefore, in order to suppress the temperature rise of the laser diode 20, the laser power is reduced as the temperature increases. As an example of the relationship between the temperature and the reproducing laser beam and the recording laser beam, the relationship shown in FIGS. 2A and 2B can be adopted. The range of power is different between the reproducing laser power and the recording laser power, but in both cases, the laser power gradually decreases as the temperature rises. From these graphs, the values of the laser power with respect to the temperature are sampled as the reproduction laser power list 48 b and the recording laser power power 48 c of the table 48 shown in FIG. In this embodiment, the number of samplings is set to 5, but this number may be changed as needed.

At normal temperature (for example, 22 degrees), that is, for a standard recording / playback laser power, the focus servo system and the tracking servo system have the response characteristics shown by the solid line A in FIG.

As shown in FIGS. 2 (A) and (B), as the temperature increases, the laser pulse decreases. When the laser power decreases, the outputs of the TE signal and the FE signal output from the TE signal detection circuit 28 and the FE signal detection circuit 30 also decrease. Therefore, in order to secure the same output of the tracking work signal and the focus work overnight signal as at the standard recording Z playback laser power, the gains of the tracking servo system and the focus support system are obtained. Raise. When the gain is increased, the response characteristic spreads to the high frequency band as shown by the solid line B in FIG. On the other hand, the temperature is low Then, since the laser power is increased, the output of the TE signal and the FE signal also increases. Therefore, in order to suppress the output of the tracking actuator signal and the focus actuating signal, the gains of the tracking servo system and the focus support system are reduced. When the gain is reduced, the response characteristic narrows to the low frequency band as shown by the solid line C in Fig. 4. Based on such a concept, the gain list 48 d of the tape 48 is prepared in such a manner that the gain values corresponding to the changing temperature are prepared by the number of change values of the recording Z reproduction laser power.

The processing operation of the microcomputer 34 in this embodiment will be described with reference to the flowchart of FIG. The microcomputer 34 periodically and repeatedly executes the processing of the flowchart of FIG. 5 in the processing operation. First, in step S1, the microcomputer 34 captures the temperature signal transmitted by the temperature sensor 24 and detects the temperature around the optical pickup 12. Next, in step S3, the microcomputer 34 compares the detected temperature with each temperature in the temperature list 48a of the table 48 in ascending order of the temperature, and finds the highest temperature lower than the detected temperature, This is determined as the temperature around the optical pickup 12.

When the reference ambient temperature is determined, the microcomputer 34 obtains the value of the reproduction laser power corresponding to the determined ambient temperature in the table 48 from the reproduction laser power list in step S5. Also, in step S7, the value of the recording laser corresponding to the ambient temperature is obtained from the recording laser power list, and in step S9, the value of the gain corresponding to the ambient temperature is obtained from the gain list. I do. In step SI1, the microcomputer 34 outputs the acquired values of the reproduction laser power, the recording laser power, and the gain to the DSP 32.

Next, the processing operation of the DSP 32 in this embodiment will be described with reference to the flowchart of FIG. First, in step S 21, the DSP 32 acquires the value of the reproduction laser power, the value of the recording laser power, and the value of the gain from the microcomputer 34. Upon obtaining the data from the microcomputer 34, the DSP 32 determines in step S23 whether the optical disk device 10 is in the reproduction mode. If it is determined that the mode is the reproduction mode, the value of the reproduction laser power obtained from the microcomputer 34 is set in the laser drive 50 in step S25. If the mode is not the reproduction mode, the value of the recording laser power is determined in step S27. Is set to laser drive 50. Setting of laser power When the setting is completed, the DSP 32 adds the gain obtained from the microcomputer 34 to the focus actuating signal at step S29, and outputs the signal to the focus actuating signal 18. Also, in step S31, a gain is given to the tracking work overnight signal, and the signal is output to the focus work overnight 14.

The laser drive 50 drives the laser diode 20 to emit a set laser beam. The tracking position and the focus position of the optical lens 16 of the optical pickup 12 are adjusted based on the tracking work overnight signal and the focus work overnight signal to which the gain is given.

As described above, in the optical disk device of this embodiment, the laser power value of the laser light oscillating according to the changing ambient temperature of the laser diode 20 is changed. Further, an optimum gain for appropriately performing the focus servo control and the tracker servo control with the changed laser power value is determined, and this gain is added to the force control signal and the tracking control signal. Therefore, irrespective of the temperature change of the peripheral temperature of the laser diode 20, the force control and the tracking control of the optical lens 16 can be appropriately performed, and the stable operation can be performed. This embodiment is not limited to the above-described example, and may be implemented with various modifications. For example, in the above-mentioned example, the actuary system was realized by DSP, but may be constituted by a filter and a driver instead.

Also, Table 48 shows the values of the reproduction laser power, recording laser power, and gain corresponding to the five temperatures of 5 degrees, 10 degrees, 22 degrees, 40 degrees, and 60 degrees. Although stored, the number and value of the temperatures to be set are not limited to these, and can be changed according to the embodiment.

Further, in the above-described embodiment, one table is used. However, a table is prepared for each value of the reproduction laser power, the value of the recording laser power, and the value of the gain, and the number of elements to be stored for each table is determined. You can change it.

Although the gain value added to the tracking work signal and the gain value added to the focus work signal are common, different gains may be added respectively.

While this invention has been described and illustrated in detail, it has been presented by way of illustration only and as an example. It is clear that they have been used and should not be construed as limiting, the spirit and scope of the invention being limited only by the language of the appended claims.

Claims

The scope of the claims

1. An optical disc device for irradiating a laser beam output from a semiconductor laser to a recording surface of an optical disc through an optical lens, comprising:

Detecting means for detecting an ambient temperature of the semiconductor laser;

Laser power reduction means for reducing the laser power value of the semiconductor laser as the ambient temperature detected by the detection means increases;

Generating means for generating a servo control signal based on the reflected light of the laser light on the recording surface;

A displacement means for displacing the optical lens in response to the support control signal; a gain table in which a plurality of temperature values and a service control gain that increases as the temperature value increases are stored in association with each other;

A servo control gain reading means for reading from the gain table a servo control gain corresponding to the ambient temperature detected by the detection means; and the generation of the servo control gain read by the support control gain reading means. Servo control gain setting means to be set in the means.

2. The disk device according to claim 1, wherein the servo control signal includes a focus control signal and a tracking control signal, and the support control gain stored in the gain table is a focus control signal. Includes gain and tracking control gain.

3. A disk device according to claim 1 or 2, wherein the plurality of temperature values and a plurality of laser power values decreasing as the temperature values increase are associated with each other; A laser power value reading means for reading a laser power value corresponding to the ambient temperature detected by the means from the laser power value table,

The laser power reducing means sets the laser power value read by the laser power value reading means as a laser power value of the semiconductor laser.