WO2007108451A1

WO2007108451A1 - Controller of optical disk device, optical disk device, control method of optical disk device

Info

Publication number: WO2007108451A1
Application number: PCT/JP2007/055572
Authority: WO
Inventors: Yuu Okada; Takeharu Yamamoto
Original assignee: Matsushita Electric Industrial Co., Ltd.
Priority date: 2006-03-20
Filing date: 2007-03-19
Publication date: 2007-09-27
Also published as: JP2009134776A

Abstract

Operation of an optical disk device is controlled based on the results of judgment as to whether control of transmittance is performed appropriately by a light control element or not. The controller of an optical disk device, comprising a laser element (11) emitting a light beam for irradiating an optical disk, a laser drive circuit (50) for driving the laser element (11) by supplying a drive current, a photodetector (15) for detecting the quantity of light of the light beam, a light control element (16) for varying transmittance of the light beam emitted from the laser element (11), and a light control elemtn drive circuit (51) for driving the light control element (16), is further provided with a laser power control section (24) for controlling the drive current of the laser drive circuit (50) such that the quantity of light emitted toward the optical disk becomes constant based on a signal outputted from the photodetector (15), a transmittance switching section (25) for controlling the light control element drive circuit (51), and a section (34) for judging whether the light control element (16) has operated normally for the setting at the transmittance switching section (25) or not and regulating the operation of the laser element (11) based on the judgment results.

Description

Specification

Technical field of optical disk device control device, optical disk device, and optical disk device control method

[0001] The present invention relates to a control method in which a light beam is converged and irradiated using an optical head equipped with a light control element when performing recording and reproduction on a disc-shaped information carrier (hereinafter referred to as an optical disk) capable of recording information. The present invention relates to a control device for an optical disk device that stably performs the above, a control method for the optical disk device, and an optical disk device that uses the control method.

Background art

In recent years, there has been a demand for optical information recording media with higher density as information capacity increases.

Here, a Blu-ray Disc (hereinafter referred to as BD) has been developed that uses a 405 nm blue laser and a converging lens with an NA of 0.85, which has a recording capacity about 5 times that of DV D.

[0003] In addition to the so-called single-layer disc having one recording / reproducing layer, a multi-layer disc having a plurality of recording / reproducing layers has been developed in order to obtain a higher recording density with the recent increase in output of blue lasers. Has been. For example, a BD with two recording layers has about 10 times the storage capacity of a DVD.

[0004] However, in the optical disk apparatus that records and reproduces the high-density optical information recording medium using the blue laser described above, the reproduction margin is very strict, so it is necessary to accurately obtain the appropriate light quantity for each recording / reproducing layer. There is. At this time, when a low light amount is required as the appropriate light amount, the quantum noise of the light source becomes a problem.

[0005] In order to solve this problem, for example, as in Patent Document 1, the surface power of the optical information recording medium is controlled within an appropriate range to prevent the optical information recording medium from being deteriorated or erased. On the other hand, there has been proposed an optical head capable of performing high-quality reproduction with low noise by suppressing the quantum noise of a semiconductor laser as a light source.

[0006] Hereinafter, the configuration and operation of the conventional technique of Patent Document 1 will be described with reference to FIG.

In the conventional optical disk apparatus shown in FIG. 13, in order to reproduce or record the optical disk 1, the laser light output from the laser element 11 built in the optical head 10 is transmitted to the optical head 10. After being collimated by the built-in coupling lens 12, the amount of light is attenuated by the dimming element 16 built in the optical head 10. A part of the parallel light is reflected by the polarization reflector 13 built in the optical head 10 and converged and irradiated onto the information recording film 2 of the optical disc 1 by the objective lens 14 built in the optical head 10.

On the other hand, a part of the parallel light passes through the polarization reflector 13 and enters a photodetector 15 built in the optical head 10. The photodetector 15 outputs a signal corresponding to the amount of incident light.

The output of the photodetector 15 is supplied to a digital signal processor (DSP) 20.

[0010] Hereinafter, the processing power based on the signal output from the photodetector 15 is performed by each unit in the DSP 20.

The signal output from the photodetector 15 is AD converted by AD conversion and supplied to the laser power control unit 24.

Upon receiving the signal from the AD-converted photodetector 15, the laser power control unit 24 converges and irradiates the information recording film 2 of the optical disc 1 based on the transmittance of the polarization reflector 13. It converts into the emitted light quantity of a light beam. The amount of emitted light is compared with a predetermined level set in the memory 26, a laser drive value that matches this predetermined level is set, and output to the DA converter 22.

[0013] DA conversion ^ 22 DA converts the laser drive value and outputs it as a laser drive signal from DSP 20 to laser drive circuit 50.

The laser drive signal output from the DSP 20 causes the laser drive circuit 50 to operate and allows a drive current to flow through the laser element 11. The laser element 11 emits light so as to obtain a predetermined laser power for the optical disc 1 based on the drive current.

On the other hand, the transmittance switching unit 25 sets a dimming driving value for switching the transmittance of the dimming element 16 according to the laser driving value and the laser power set by the laser power control unit 24. Is output to the DA converter 23. The DA converter 23 DA-converts the dimming drive value to generate a dimming drive signal and outputs it to the outside of the DSP 20.

[0016] The dimming drive signal output from the DSP 20 is switched by operating the dimming element driving circuit 51 to cause a driving current to flow through the dimming element 16, and changing the transmittance of the dimming element 16. The transmittance switching unit 25 performs control to switch the transmittance of the light control element 16 according to the operation on the optical disc 1.

[0018] Specifically, when information from the optical disc 1 is reproduced, the laser power control unit 24 sets the laser power high so as to be suitable for reproduction while suppressing the generation of quantum noise. The transmittance switching unit 25 switches so as to reduce the transmittance so as to reduce the amount of laser light applied to the optical disc 1. Further, when information is recorded on the optical disc 1, the transmittance switching unit 25 switches so as to increase the transmittance so that the amount of emitted light is suitable for recording.

[0019] According to this conventional optical disc apparatus, during reproduction, the driving current of the laser element 11 is increased and the light amount is attenuated by the dimming element 16, so that the quantum noise is kept sufficiently low even with the same laser power. It can be in the state. During recording, the light control element 16 emits light with a laser power within the range of the drive current that can be withstood by the laser element 11 without attenuating the light quantity, and can record with a quantity of emitted light sufficient to maintain the recording quality. Patent Document 1: JP 2000-195086

Disclosure of the invention

Problems to be solved by the invention

[0020] However, the following problems have been encountered in the above-described conventional optical disc apparatus.

In the above configuration, the light control element 16 and the light control element drive circuit 51 have, as a specific example, a fixed transmittance that transmits parallel light after passing through the coupling lens 12. It is realized as a possible light quantity attenuating member and its driving device. In this case, the drive device drives the light attenuation member in accordance with the dimming drive signal to create a state in which the light attenuation member is disposed or not disposed on the optical path of the parallel light. The transmittance of the parallel light passing through the light control element 16 is changed.

[0022] Another specific example is realized as a liquid crystal element that transmits parallel light after passing through the coupling lens 12, and a voltage applying device thereof. In this case, the voltage application device applies a voltage to the liquid crystal element in accordance with the dimming drive signal to change the transmittance of the liquid crystal, thereby transmitting the parallel light passing through the dimming element 16 as the liquid crystal element. Change the rate. [0023] At this time, in the configuration using the light amount attenuating member and the driving device, the light control element 16 may not operate normally due to the movement of the light amount attenuating member being stopped due to the influence of vibration due to external force. .

On the other hand, in the configuration using the liquid crystal element and the voltage applying device, the light control element is caused by a change in characteristics of the liquid crystal used in the liquid crystal element or a variation in transmittance based on individual differences of the liquid crystal elements. 16 may not change to the desired transmittance. In particular, the transmissivity of the liquid crystal may not change within a predetermined time until the recording operation (or trial writing operation) is shifted from the reproduction operation with a slow response speed.

As described above, the dimming element 16 does not transmit light regardless of any of the above-described configurations, although the dimming driving signal from the DSP 20 and the driving current from the dimming element driving circuit 51 are normally output. There may be a situation where the excess rate does not change properly.

In this case, the adjustment of the quantity of emitted light is not performed normally, and the following problems occur.

That is, when a malfunction occurs in the light control element during information reproduction from the optical disc 1, light with insufficient light amount attenuation is input to the photodetector 15. At this time, since the laser power control unit 24 performs control to reduce the laser power so that the amount of emitted light is reduced, the laser element 11 has a laser power that is less than a necessary value, and the quantum noise increases. Therefore, playback quality deteriorates.

In addition, when a malfunction occurs in the light control element 16 during information recording on the optical disc 1, light with unnecessary light amount attenuation is input to the photodetector 15. At this time, since the laser power control unit 24 performs control to increase the laser power so that the amount of emitted light increases, the laser element 11 is caused to emit light with a drive current exceeding the maximum output of the laser element 11, and the laser element 11 is deteriorated.

[0029] The present invention has been made to solve the above-described problem, and determines whether or not the transmittance control by the light control element is appropriately performed, and controls the operation based on the result. It is an object of the present invention to provide a control device for an optical disc device capable of performing the same and an optical disc device using the same.

Means for solving the problem [0030] In order to achieve the above object, the first aspect of the present invention includes a laser element that emits a light beam that irradiates an optical disc, a laser drive unit that drives the laser element by supplying a drive current, An optical disc apparatus comprising: a light amount detection unit that detects a light amount of a light beam; a dimming element that changes a transmittance of the light beam emitted from the laser element; and a dimming element driving unit that drives the dimming element. A control device of

A power control unit that controls the drive current of the laser drive unit so that the amount of light emitted to the optical disc is constant based on the output of the light amount detection unit;

A transmittance control unit for controlling the light control element driving unit;

An optical disc apparatus comprising: an adjustment unit that determines whether or not the dimming element operates normally with respect to the setting of the transmittance control unit, and adjusts the operation of the laser element according to the determination result It is a control device.

[0031] In the second aspect of the present invention, the adjustment unit measures a light amount measurement unit that measures an output of the light amount detection unit before and after the operation of the dimming element driving unit, and

A control device for an optical disc apparatus according to the first aspect of the present invention, comprising: a dimming element state determination unit that compares respective measurement results of the light amount measurement unit and determines the state of the dimming element from the comparison result. is there.

The third aspect of the present invention is the control device for the optical disc apparatus according to the second aspect of the present invention, wherein the output current of the laser driving unit is kept constant at least during the operation of the light quantity measuring unit.

[0033] Further, in the fourth aspect of the present invention, the adjustment unit uses, as drive efficiency of the drive current, a change in the output of the light detection unit when the drive current of the laser drive unit is changed. A driving efficiency detection unit that detects before and after the operation of the dimming element driving unit;

Control of the optical disk device of the first aspect of the present invention, comprising: a dimming element state determination unit that compares the driving efficiencies of the driving efficiency detection units and determines the state of the dimming element. Device.

[0034] Further, according to a fifth aspect of the present invention, the adjusting unit is configured to measure the laser driving value set in the laser driving unit by the power control unit before and after the operation of the dimming element driving unit. A value measuring unit; A control device for an optical disc apparatus according to the first aspect of the present invention, comprising: a dimming element state determination unit that compares the measurement results of the drive value measurement unit and determines the state of the dimming element from the comparison result .

[0035] Further, according to a sixth aspect of the present invention, when the drive value measurement unit is operating, the output of the laser drive unit is controlled so as to keep the output of the light detection unit constant. It is a control apparatus of the optical disk apparatus of this invention.

[0036] Further, according to a seventh aspect of the present invention, when the adjustment unit determines that the dimming element is not operating normally, the adjustment unit adjusts the output of the laser driving unit to be further limited. It is a control apparatus of the optical disk apparatus of this invention.

[0037] Further, in the eighth aspect of the present invention, the light control element includes a light amount attenuating member having a constant transmittance,

The light control element driving unit is a control device for the optical disc apparatus according to the first aspect of the present invention, which moves the light amount attenuating member on an optical path formed by light emitted from the laser element.

[0038] Further, the ninth aspect of the present invention is the liquid crystal element, wherein the light control element has a stepless change in transmittance according to an applied voltage from the light control element driving unit,

When the dimming element state determination unit determines that the dimming element state is normal !, the dimming element state determination unit controls the dimming element driving unit to match the setting of the transmittance control unit. It is the control device for the optical disk device of the second or fourth aspect of the present invention.

[0039] Further, the tenth aspect of the present invention is the optical disc apparatus according to the first aspect of the present invention, wherein the adjusting unit prohibits the recording operation of the optical disc when it is determined that the dimming element is not operating normally. Control device.

[0040] Further, in the eleventh aspect of the present invention, when the adjusting unit determines that the dimming element is not operating normally, the adjusting unit stops the operation of the dimming element driving unit and restarts the force. 1 is a control device of an optical disk device according to the first aspect of the present invention;

[0041] Further, the twelfth aspect of the present invention is the control device for an optical disc apparatus according to the eleventh aspect of the present invention, wherein the dimming element driving unit makes the output of the dimming element driving unit larger during re-operation than before re-operation. is there.

[0042] Further, in a thirteenth aspect of the present invention, the light amount detection unit uses the optical disc as the emitted light amount. 1 is a control device for an optical disk device according to the first aspect of the present invention, which detects the amount of reflected light of a light beam irradiated on the optical disk device.

Further, the fourteenth aspect of the present invention is a laser element that emits a light beam that irradiates an optical disc, a laser drive unit that drives the laser element by supplying a drive current, and detects the amount of light of the light beam A light amount detecting unit that changes the transmittance of the light beam emitted from the laser element, a light control element that changes in a stepless manner according to an applied voltage, and a light control element that drives the light control element. A power control unit for controlling the drive current of the laser drive unit so that the amount of light emitted to the optical disc is constant based on the output of the light amount detection unit; ,

It is a control device for an optical disc apparatus, comprising a transmittance control unit that controls the light control element driving unit so as to coincide with a predetermined target value.

The fifteenth aspect of the present invention is the optical disc according to the fourteenth aspect of the present invention, wherein the transmittance control unit controls the dimming element driving unit using the output of the light amount detection unit and the target value. It is a control device for the device.

In the sixteenth aspect of the present invention, the transmittance control unit is configured to determine a change in the output of the light detection unit when the driving current of the laser driving unit is changed. And a driving efficiency detection unit that detects before and after the operation of the light control element driving unit,

A control device for an optical disk device according to a fourteenth aspect of the present invention, wherein the drive efficiencies of the drive efficiency detectors are compared, and the liquid crystal element driver is controlled using the comparison result and the target value.

[0046] Also, in the seventeenth aspect of the present invention, the drive efficiency detection unit uses at least two outputs of the laser drive unit and measures the output of the light detection unit according to each output. Then, the control device for the optical disk device according to the sixteenth aspect of the present invention, wherein the drive efficiency is determined using linear approximation calculation.

[0047] In addition, the eighteenth aspect of the present invention further includes a characteristic change detection unit that detects that the characteristic of the light control element has changed, and causes the transmittance control unit to operate again according to the detection result. 14 It is a control apparatus of the optical disk apparatus of this invention.

[0048] Further, the nineteenth aspect of the present invention is the optical disc apparatus according to the first or fourteenth aspect of the present invention, further comprising a memory for holding a measured value of the light amount of the light beam when the transmittance control unit changes. It is a control device.

[0049] Further, the twentieth aspect of the present invention is a laser element that emits a light beam that irradiates an optical disc, a laser driving unit that drives the laser element by supplying a driving current,

A light amount detector for detecting the light amount of the light beam;

A dimming element that changes the transmittance of the light beam emitted from the laser element, and a dimming element driving unit that drives the dimming element,

An optical disc having the control device of the optical disc device of the first or fourteenth aspect of the present invention as a power control portion for controlling the drive current of the laser drive portion and a control portion for controlling the operation of the dimming element drive portion. Device.

[0050] Further, the twenty-first aspect of the present invention provides a laser element that emits a light beam that irradiates an optical disc, a laser drive unit that drives the laser element by supplying a drive current, and detects the amount of light of the light beam. And a dimming element driving unit for driving the dimming element, and a method for controlling the optical disk device, comprising: a light amount detecting unit for controlling the light beam; a dimming element for changing a transmittance of the light beam emitted from the laser element; And

A power control step of controlling the drive current of the laser drive unit so that the amount of light emitted to the optical disk is constant based on the output of the light amount detection unit;

A transmittance control step for controlling the light control element driving unit;

An optical disc apparatus control comprising: an adjustment step that determines whether the light control element is operating normally with respect to the setting in the transmittance control step and adjusts the operation of the laser element according to the determination result Is the method.

The invention's effect

[0051] According to the present invention as described above, it is possible to determine whether or not the transmittance is properly controlled by the light control element, and to control the operation of the optical disc apparatus based on the result. . For example, in order to cover a wide dynamic range from single-layer playback power to multi-layer recording power, quantum noise is reduced by reducing the transmittance during playback, and transmission during recording. Even with a configuration that increases the rate, laser power can be controlled safely without placing a burden on the light source.

Brief Description of Drawings

FIG. 1 is a diagram showing a block configuration of an optical disc apparatus according to Embodiment 1 of the present invention.

FIG. 2 is a flowchart illustrating the operation of the optical disc device according to the first embodiment of the present invention.

FIG. 3 is a graph showing a relationship between the amount of emitted light, drive current, and transmittance in the optical disc apparatus according to Embodiment 1 of the present invention.

FIG. 4 is a diagram showing a block configuration of an optical disc apparatus according to Embodiment 2 of the present invention.

FIG. 5 is a flowchart illustrating the operation of the optical disc device according to the second embodiment of the present invention.

FIG. 6 is a graph showing the relationship between the amount of emitted light, the drive current, and the transmittance in the optical disc device according to the second embodiment of the present invention.

FIG. 7 is a block diagram showing an optical disk device according to a third embodiment of the present invention.

FIG. 8 is a diagram showing a block configuration of an optical disc apparatus according to Embodiment 4 of the present invention.

FIG. 9 is a diagram showing another configuration example of the optical disc device according to the third embodiment of the present invention.

FIG. 10 is a diagram showing a block configuration of an optical disc device according to a fifth embodiment of the present invention.

FIG. 11 is a graph showing the relationship between the amount of emitted light, the drive current, and the transmittance in the optical disc device according to the fifth embodiment of the present invention.

FIG. 12 is a diagram showing the configuration of another configuration example of the optical disc apparatus of the present invention.

FIG. 13 is a diagram showing a block configuration of an optical disc apparatus in the background art

Explanation of symbols

[0053] 1 Optical disc

2 Information recording film

10 Optical head

11 Laser element

12 Coupling lens

13 Polarizing reflector 14 Objective lens

15 photodetector

16 Light control element

17 Temperature sensor

18 1Z4 wave plate

20 DSP

21 AD

22 DA

23 DA

24 Laser power controller

25 Transmittance switching section

25a memory

30 Light intensity measurement unit

31 Drive efficiency detector

32 Drive efficiency measurement unit

33 memory

34 Dimming element operation judgment unit

35 Light control element operation judgment part

36 Transmittance adjuster

37 Transmittance adjuster

38 Light control element operation judgment part

39 Drive measurement unit

40 switches

50 Laser drive circuit

51 Light control element drive circuit

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described.

[Embodiment 1] The configuration and operation of the optical disc apparatus according to the first embodiment will be described with reference to the block configuration of FIG. In FIG. 1, the same components as those in FIG. 13 which is the background art are denoted by the same reference numerals.

Of the configuration of the optical disk device according to the first embodiment, a laser element that emits a light beam that irradiates an optical disk, a laser drive unit that supplies a drive current to drive the laser element, A light amount detection unit for detecting the amount of light; a dimming element for changing the transmittance of the light beam emitted from the laser element; a dimming element driving unit for driving the dimming element; and an output of the light amount detection unit And a light control unit that controls the drive current of the laser drive unit so that the amount of light emitted to the optical disk is constant, and a transmittance that controls the light control element drive unit based on the output of the light amount detection unit The configuration including the control unit and the operation thereof are the same as in the conventional example. That is, in order to reproduce or record the optical disk 1, the laser light output from the laser element 11 built in the optical head 10 is attenuated by the light control element 16 built in the optical head 10, The light is collimated by a coupling lens 12 built in the optical head 10. A part of the parallel light is reflected by the polarization reflector 13 built in the optical head 10 and converged and irradiated onto the information recording film 2 of the optical disc 1 by the objective lens 14 built in the optical head 10.

On the other hand, a part of the parallel light passes through the polarization reflector 13 and enters the photodetector 15 built in the optical head 10. The photodetector 15 detects an output corresponding to the amount of incident light.

[0058] A signal output from the photodetector 15 corresponding to the amount of emitted light is input to the DSP 20, converted into the amount of emitted light, and processing based on this is performed by each unit in the DSP 20.

[0059] The signal output from the photodetector 15 is AD-converted by AD conversion, and is input to the laser power control unit 24 to obtain laser power as a control target value corresponding to the amount of light applied to the optical disc 1. Used to generate laser drive values.

[0060] DA conversion ^ 22 DA converts the laser drive value and outputs the laser drive signal from the DSP 20 to the laser drive circuit 50.

The laser drive signal output from the DSP 20 causes the laser drive circuit 50 to operate and allows a drive current to flow through the laser element 11. Based on the drive current, the laser element 11 emits light so that a predetermined amount of emitted light can be obtained with respect to the optical disc 1. On the other hand, the transmittance switching unit 25 sets a dimming drive value for switching the transmittance of the dimming element 16 according to the laser power set by the laser power control unit 24 and the amount of emitted light described later. This is output to the DA converter 23. The DA converter 23 DA-converts the dimming drive value to generate a dimming drive signal and outputs it to the outside of the DSP 20.

The dimming drive signal output from the DSP 20 is switched by operating the dimming element driving circuit 51 to flow a driving current through the dimming element 16 and changing the transmittance of the dimming element 16.

The transmittance switching unit 25 performs control to switch the transmittance of the light control element 16 according to the operation on the optical disc 1.

Specifically, when reproducing information from the optical disc 1, the laser power control unit 24 increases the laser drive value so that the amount of emitted light is suitable for reproduction while suppressing the generation of quantum noise. Since the setting is made, the transmittance switching unit 25 switches the transmittance so as to decrease the light amount of the laser light irradiated onto the optical disc 1. Further, when information is recorded on the optical disc 1, the transmittance switching unit 25 switches so as to increase the transmittance so that the amount of emitted light is suitable for recording.

In the present embodiment, the dimming element 16 and the dimming element driving circuit 51 have a fixed transmittance that transmits the parallel light after passing through the coupling lens 12, and the movable light amount is attenuated. The member and its driving device were used. In this case, the drive device drives the light amount attenuating member according to the dimming drive signal to create a state in which the light amount attenuating member is disposed or not disposed on the optical path of the parallel light. The transmittance of parallel light passing through the optical element 16 is changed.

[0067] In addition to the above configuration, the optical disc apparatus according to the first embodiment further determines whether the dimming element operates normally with respect to the setting of the transmittance control unit, and responds to the determination result. And an adjustment unit for adjusting the operation of the laser element. In FIG. 1, the adjustment unit includes a switch 40, a light amount measurement unit 30, and a light control element operation determination unit 34.

Upon receiving the signal output from the light detector 15, the light quantity measurement unit 30 outputs the light beam that converges and irradiates the information recording film 2 of the optical disc 1 based on the transmittance of the polarization reflector 13. It is a means for converting to and measuring. The measurement of the amount of emitted light is performed before and after the transmittance of the light control element 16 is switched by the transmittance switching unit 25. Memory 33 stores the measured light output. It is a means to exist. The light control element operation determination unit 34 is a means for determining whether or not the emitted light amount measured by the light amount measurement unit 30 and stored in the memory 33 changes normally before and after switching the transmittance. The switch 40 is a means for switching the output detected by the photodetector 15 to either the laser power control unit 24 or the light amount measurement unit 30 and outputting the switched output.

[0069] In the above configuration, the DSP 20 corresponds to the control device of the optical disk device of the present invention, and the optical disk device corresponds to the optical disk device of the present invention.

[0070] Further, the laser power control unit 24 corresponds to a power control unit and an adjustment unit of the present invention, and the switch 40, the light amount measurement unit 30 and the dimming element operation determination unit 34 correspond to an adjustment unit of the present invention, The transmittance switching unit 25 corresponds to the transmittance control unit of the present invention. The light quantity measurement unit 30 corresponds to the light quantity measurement unit of the present invention, and the light control element operation determination unit 34 corresponds to the light control element state determination unit of the present invention. The memory 33 corresponds to the memory of the present invention.

[0071] Further, the laser element 11 is the laser element of the present invention, the laser drive circuit 50 is the laser drive section of the present invention, the photodetector 15 is the light amount detection section of the present invention, and the light control element 16 is the present invention. The dimming element driving circuit 51 corresponds to the dimming element driving unit of the present invention.

[0072] The operation of the optical disk apparatus according to the first embodiment having the above-described configuration will be described, and the embodiment of the control apparatus for the optical disk apparatus according to the present invention will be described with reference to the flowchart of FIG. And explain.

[0073] First, in the DSP 20, the laser power control unit 24 turns on laser power control (step S101). In this state, the laser power control unit 24 does not perform transmittance switching control on the transmittance switching unit 25, and the dimmer driving circuit 51 and the dimmer 16 do not operate, that is, the transmittance is 100%. Suppose that it is in a state.

Next, the laser power control unit 24 holds power control so that the laser drive circuit 50 allows a constant value of drive current to flow through the laser element 11 (step S102). As a result, the drive current of the laser drive circuit 50 is fixed, and the laser element 11 outputs a light beam with a constant drive current.

[0075] Next, in DSP 20, the switch 40 is switched to be connected to the light quantity measurement unit 30, and the signal output from the photodetector 15 that has received the light beam from the laser element 11 is measured by the light quantity measurement unit. Supplied to part 30. Based on this output signal, the light quantity measuring unit 30 performs power control. The amount of emitted light PI with respect to a certain fixed driving current is measured, and the measurement result is recorded in the memory 33 (step S103).

Next, the laser power control unit issues a command for switching the transmittance to the transmittance control unit 25. In response to the command, the transmittance control unit 25 drives the dimming element driving circuit 51 to switch the transmittance from 100% to 50%. The dimming element drive circuit 51 performs an operation of inserting the dimming element 16 into the optical path (step S104).

Furthermore, the laser power control unit 24 emits laser light under the same conditions as in step S102. In the same manner as in step S103, the light quantity measuring unit 103 measures the emitted light quantity P2 when the transmittance switching command is issued, and records the measurement result in the memory 33 (step S105). At this time, the light amount measurement unit 30 receives the transmittance switching command from the laser power control unit 24, and stores the emitted light amount and the transmittance in the memory 33 in association with each other. Note that the memory 33 may be directly instructed to associate the emitted light quantity with the transmittance during recording (corresponding to the dotted line in the figure).

Next, the light control element operation determination unit 34 reads out the emitted light amounts P1 and P2 from the memory 33, and compares them to determine the force at which the transmittance is normally switched, that is, the light control element. It is determined whether 16 is operating normally (step S106).

Here, FIG. 3 is a graph showing the relationship between the transmittance during the power control hold and the amount of emitted light. As shown in the figure, the emitted light quantity Pl before and after switching the transmittance by driving the laser element with a constant driving current il (for example, il = 23 mA) for which power control is held in step S102. P2 is obtained, and whether or not the change in the transmittance is normally performed is determined by determining whether or not the change in the set transmittance uniquely corresponds to the change in the amount of emitted light.

[0080] In this case, the switching of the transmittance is a change from 100% to 50%. The intensity of the emitted light P1 and P2 actually measured by the light intensity measurement unit 103 is also changed uniquely according to the change in the transmittance. If so, it is determined that the transmission has been switched normally, and otherwise it has not been switched normally. As a specific example, if the output light quantity P1 = 0.6 ± 0.06 mW and the output light quantity P2 = 0.3 ± 0.03 mW are measured for the change in the transmittance of 50%, switching is performed normally. You can see that it was broken. Note that the comparison between the change in transmittance and the change in the amount of emitted light is not limited to a specific method. It may be a comparison between a set difference in transmittance and a difference in emitted light amount, or may be a comparison between a set transmittance ratio and an emitted light amount ratio.

If the dimming element operation determination unit 34 determines that the transmittance is switched normally as a result of the determination, the dimming element operation determination unit 34 outputs the result to the laser power control unit 24. In response to this, the laser power control unit 24 releases the power control hold (step S108), switches the switch 40 to the laser power control unit 24 side, and reproduces information from the optical disc 1 (step S109). At this time, the laser power control unit 24 converts the signal output from the photodetector 15 into the amount of emitted light.

[0083] Since the reproduction operation at this time is accurately operated at a transmittance of 50% under the control of the transmittance switching unit 25, the laser power control unit 24 is configured so that the quantum noise of the laser element 11 is reduced. While controlling the laser drive circuit 50 with high output, the optical disk 1 can be irradiated with a light beam with an emitted light amount suitable for reproduction.

On the other hand, if the dimming element operation determination unit 34 determines that the transmittance switching is not normally performed as a result of the determination, the dimming element operation determination unit 34 causes the dimming element drive circuit 51 to pass through the transmittance switching unit 25. Reactivate (Step S107), and then repeat Steps S103 to S106.

[0085] By performing the operation again in step S107, even if the dimming element 16 realized by the light quantity attenuation member or the like does not operate due to the influence of external vibration or the like, the operation can be normally performed by a plurality of executions. it can. Note that the drive voltage of the light control element 16 may be gradually increased during the re-operation. In this case, the light control element 16 can be more reliably operated while further reducing the initial drive voltage to reduce power consumption. If normal operation is not performed after re-operation, the operation of the optical disk device itself is stopped. As a result, it is possible to prevent the optical disc apparatus from operating with an inaccurate transmittance.

[0086] Note that the power control hold time maintained in each of the above steps is preferably within the range of lms to 100 ms. The time required for the DSP 20 to process each step must be at least lms, and if the hold time exceeds 100 ms, the laser element 11 will change in temperature and will not be able to maintain a constant output. Because. This control is the same in the following embodiments. Next, even when the optical disc 1 completes the reproduction operation and performs the recording operation, it is determined in advance whether or not the transmittance is normally switched by the light control element 16. The basic operation is the same as that before the reproducing operation, and the power control is held so that the laser drive circuit 50 allows a constant value of drive current to flow through the laser element 11 (step S110). Here, as shown in FIG. 3, the drive current i2 at the time of holding is larger than the drive current il at the time of holding in step S102 (for example, i2 = 26 mA)). This is because the drive current is controlled in step SI 08 so that the playback capacity becomes P1.

The switch 40 is switched again so as to be connected to the light quantity measurement unit 30, and the signal output from the photodetector 15 that has received the light beam from the laser element 11 is supplied to the light quantity measurement unit 30. The light quantity measuring unit 30 measures the emitted light quantity P1 with respect to the held drive current i2, and records the measurement result in the memory 33 (step S111).

Further, the laser power control unit issues a command for switching the transmittance to the transmittance control unit 25. In response to the command, the transmittance control unit 25 drives the dimming element driving circuit 51 to switch the transmittance from 50% to 100%. The dimming element driving circuit 51 executes an operation for eliminating the optical path force of the dimming element 16 (step S112).

[0090] The laser power control unit 24 emits laser light under the same conditions as in step S111, and the light amount measurement unit 103 measures the emitted light amount P3 when the transmittance switching command is issued in the same manner as in step S111. Then, the measurement result is recorded in the memory 33 (step S113).

Next, the dimming element operation determining unit 34 reads out the emitted light amounts P1 and P3 from the memory 33, and compares them to determine the force at which the transmittance is normally switched, that is, the dimming element. It is determined whether 16 is operating normally (step S116).

[0092] In the present embodiment, the change of transmittance is a change from 50% to 100%. As a specific example, the amount of emitted light P1 = 0.6 ±± If 0.12 mW and the amount of emitted light P3 = l. 2 ± 0.24 mW are measured, then the switch has been performed normally.

Step S116 is executed in the same manner as Step S106. When it is determined that the transmittance is switched normally by the light control element 16, the result is output to the laser power control unit 24. In response to this, the laser power control unit 24 solves the power control hold. (Step SI17), the switch 40 is switched to the laser power control unit 24 side, and the recording operation to the optical disk 1 is performed (step S118).

On the other hand, as a result of the determination, if it is determined that the switching of the transmittance has not been performed normally, the dimming element driving circuit 51 is restarted via the transmittance switching unit 25 (step S115). Steps S103 to S106 are repeated. If the normal operation is performed after the re-operation, the process proceeds to step S118. If the normal operation is not performed, the operation of the optical disc apparatus itself is stopped.

As described above, in the optical disc apparatus according to the present embodiment, it is determined whether the change in the amount of emitted light is normal according to the transmittance switching control, and only when it is determined that it is normal. Playback or recording on the optical disc 1 can be performed. Therefore, it is possible to reduce the influence of quantum noise or the like during reproduction, and it is possible to prevent deterioration of the laser element 11 during recording.

[Embodiment 2]

The configuration and operation of the optical disc apparatus according to the second embodiment will be described with reference to the block configuration of FIG. In FIG. 4, the same components as those in FIGS. 1 and 13 are denoted by the same reference numerals, and detailed description thereof is omitted.

In the optical disc device according to the second embodiment, the change in the output of the light detection unit when the adjustment unit changes the drive current of the laser drive unit is defined as the drive efficiency of the drive current. And comparing the drive efficiencies of the drive efficiency detectors to be detected before and after the operation of the dimmer element driver and the drive efficiency detectors, and from the comparison result, the state of the dimmer element A dimming element state determination unit for determining

In the above configuration, as shown in FIG. 4, the drive efficiency detection unit 31, the drive efficiency measurement unit 32, the memory 33, and the dimming element operation determination unit 35 correspond to the adjustment unit of the present invention. The driving efficiency detector 31 and the driving efficiency measuring unit 32 correspond to the driving efficiency detecting unit of the present invention, and the memory 33 and the dimming element operation determining unit 35 correspond to the dimming element state determining unit of the present invention.

[0099] In the DSP 20 of the optical disc device according to the first embodiment, the switch 40, the light amount measuring unit 30, and And a dimming element operation determination unit 34, and a drive efficiency detection unit 31, a drive efficiency measurement unit 32, and a dimming element operation determination unit 35 are incorporated.

[0100] The drive efficiency detector 31 detects and outputs the change in the amount of emitted light based on the signal output by the photodetector 15 when the drive current of the laser element 11 is changed as the drive efficiency of the drive current with respect to the amount of emitted light. It is means to do.

[0101] The drive efficiency is, for example, from 1. OmW to 2.0 mW when the drive power of the laser element 11 is changed from 30 mA to 40 mA. In some cases, it is expressed as (2. OmW— 1. OmW) / (40mA-30mA) = 0.lmWZmA.

[0102] The driving efficiency measuring unit 32 is a means for measuring the driving efficiency before and after the transmittance switching control. The light control element operation determination unit 35 is a means for determining whether or not the drive efficiency measured by the drive efficiency measurement unit 32 and stored in the memory 33 has changed normally before and after switching the transmittance.

[0103] The optical disc device of the second embodiment as described above uses the driving efficiency as a parameter instead of the emitted light quantity of the first embodiment, and determines whether or not the light control element 16 is operating properly. It is characterized by doing so.

Hereinafter, the operation of the optical disk device of the second embodiment will be described, and the flowchart of FIG. 5 and the graph of FIG. 6 will be referred to for the embodiment of the control device of the optical disk device of the present invention. And explain.

[0105] First, in the DSP 20, the laser power control unit 24 turns on laser power control (step S201). Note that the transmission rate in this state is assumed to be 100% as in step S101 of the first embodiment.

Next, the laser power control unit 24 controls the laser driving circuit 50 so that the output from the photodetector 15 corresponds to the emitted light amount P1. The drive efficiency detection unit 31 acquires the emitted light amount P1 and the drive current ia when the laser drive circuit 50 corresponding to this is controlled (step S202).

Next, the laser power control unit 24 controls the laser driving circuit 50 so that the output from the photodetector 15 corresponds to the emitted light amount P2. The drive efficiency detector 31 is the same as step S202. Thus, the amount of emitted light P2 and the drive current ib when the laser drive circuit 50 corresponding to this is controlled are acquired (step S203). Each emitted light quantity Pl, P2 and drive currents ia, ib are sent to the drive efficiency measurement unit 32. The drive efficiency measurement unit 32 sets D (100) = (P2— Pl) Z as drive efficiency D with 100% transmittance. Measure (ib-ia) and record the measurement result in memory 33.

[0108] Next, the laser power control unit issues a command to switch the transmittance to the transmittance control unit 25, and the transmittance control unit 25 drives the dimming element so as to switch the transmittance from 100% to 50%. The circuit 51 is driven. The dimming element driving circuit 51 performs an operation of inserting the dimming element 16 into the optical path (step S204).

Furthermore, the laser power control unit 24 controls the laser drive circuit 50 so that the output from the photodetector 15 corresponds to the emitted light amount P 1 under the same conditions as in step S202. The drive efficiency detection unit 31 acquires the emitted light quantity P1 and the drive current ic when the laser drive circuit 50 corresponding to this is controlled (step S205).

Next, the laser power control unit 24 controls the laser driving circuit 50 so that the output from the photodetector 15 corresponds to the emitted light amount P2 under the same conditions as in step S203. Similarly to step S202, the drive efficiency detector 31 acquires the emitted light amount P2 and the drive current id when the laser drive circuit 50 corresponding to this is controlled (step S206). Each output light amount Pl, P2 and drive current ic, id are sent to the drive efficiency measurement unit 32, and the drive efficiency measurement unit 32 sets D (50) = (P2— Pl) Z ( id—Measure ic) and record the measurement result in memory 33.

[0111] Next, the dimming element operation determination unit 34 reads the driving efficiencies D (100) and D (50) from the memory 33, compares them, and the transmittance is switched normally. That is, it is determined whether or not the light control element 16 operates normally (step S207).

Here, as shown in FIG. 6, the driving efficiency D (100) obtained at the completion of step S203 and the driving efficiency D (50) obtained at the completion of step S206 after switching the transmittance To see if the change in transmittance and the change in drive efficiency correspond to each other. to decide.

[0113] In this case, the change of transmittance is a change from 100% to 50%. Force Drive efficiency measurement unit 32 The measured drive efficiency D (100) and drive efficiency D (50) also change the transmittance. Uniquely If the corresponding change is made, it is judged that the transmittance is switched normally, and if not, the switching is performed normally.

[0114] Note that the comparison between the change in transmittance and the change in drive efficiency is not limited to a specific method. It may be a comparison between the set transmittance difference and the drive efficiency difference, or a comparison between the set transmittance ratio and the drive efficiency ratio.

[0115] If the light control element operation determination unit 34 determines that the transmittance is switched normally as a result of the determination, the light control element operation determination unit 34 outputs the result to the laser power control unit 24. In response to this, the laser power control unit 24 controls the laser drive circuit 50 so that the output from the light detector 15 corresponds to the emitted light quantity P1, and switches the switch 40 to the laser power control unit 40 side to switch the optical disk. Information reproduction from 1 is performed (step S210).

[0116] Since the reproduction operation at this time is accurately operated at a transmittance of 50% under the control of the transmittance switching unit 25, the laser power control unit 24 operates at a high output power with a low quantum noise. While controlling the drive circuit 50, the optical disk 1 can be irradiated with an optical beam at a laser power suitable for reproduction.

[0117] On the other hand, if the dimming element operation determination unit 34 determines that the transmittance is not normally switched as a result of the determination, the dimming element operation determination unit 34 passes the dimming element driving circuit 51 through the transmittance switching unit 25. Operate again (step S 208), and then repeat steps S 202 to S 206.

[0118] By performing the operation again in step S208, even if the dimming element 16 realized by the light quantity attenuation member or the like does not operate due to the influence of external vibration or the like, it can be operated normally by multiple executions. it can. Furthermore, by reducing the drive voltage from that during normal operation, it is possible to suppress power consumption during normal drive of the dimming element 16. Further, the driving voltage of the light control element 16 may be gradually increased during the re-operation. In this case, the light control element 16 can be operated more reliably after the initial drive voltage is further reduced to reduce power consumption. If normal operation is not performed after re-operation, the operation of the optical disk device itself is stopped.

[0119] Next, even when the optical disc 1 completes the reproduction operation and performs the recording operation, it is determined in advance whether or not the transmittance is normally switched by the light control element 16. As in the case before the reproduction operation, the laser power control unit 24 uses the output from the light detector 15 as the outgoing light. The laser drive circuit 50 is controlled to correspond to the quantity PI. In this case, since the reproduction operation in step S210 is taken over, the transmittance in this state is 100%.

[0120] The drive efficiency detector 31 acquires the emitted light quantity P1 and the drive current ic when the laser drive circuit 50 corresponding to this is controlled (step S212).

Next, the laser power control unit 24 controls the laser driving circuit 50 so that the output from the photodetector 15 corresponds to the emitted light amount P2. The drive efficiency detector 31 acquires the emitted light quantity P2 and the drive current id when the laser drive circuit 50 corresponding to this is controlled (step S212). Each output light quantity Pl, P2 and drive current ic, id are sent to the drive efficiency measurement unit 32, and the drive efficiency measurement unit 32 sets D (50) = (P2— Pl) Z ( id—Measure ic) and record the measurement result in memory 33.

[0122] Next, the laser power control unit issues a command to switch the transmittance to the transmittance control unit 25, and the transmittance control unit 25 drives the dimming element so as to switch the transmittance from 50% to 100%. The circuit 51 is driven. The dimming element driving circuit 51 performs an operation of inserting the dimming element 16 into the optical path (step S213).

Furthermore, the laser power control unit 24 controls the laser driving circuit 50 so that the output from the photodetector 15 corresponds to the emitted light amount P 1 under the same conditions as in step S211. The drive efficiency detector 31 acquires the emitted light quantity P1 and the drive current ia when the laser drive circuit 50 corresponding to this is controlled (step S214).

Next, the laser power control unit 24 controls the laser drive circuit 50 so that the output from the photodetector 15 corresponds to the emitted light amount P2 under the same conditions as in step S212. Similarly to step S202, the drive efficiency detection unit 31 acquires the emitted light amount P2 and the drive current ib when the laser drive circuit 50 corresponding to this is controlled (step S215). Each output light quantity Pl, P2 and drive currents ia, ib are sent to the drive efficiency measurement unit 32. The drive efficiency measurement unit 32 sets D (100) = (P2— Pl) Z ( ib—ia) and record the measurement result in memory 33.

[0125] Next, the dimming element operation determination unit 34 reads the driving efficiencies D (50) and D (100) from the memory 33, compares them, and the transmittance is switched normally. That is, it is determined whether or not the dimming element 16 operates normally (step S216). [0126] The content of the determination is the same as in step S207, except that the transmittance is changed from 50% to 100%, and the transmittance is normally switched by the dimming element 16. If it is determined that the power is off, the result is output to the laser power control unit 24. In response to this, the laser power control unit 24 controls the amount of emitted light P1 (step S218), and then controls the amount of emitted light corresponding to the recording on the optical disc 1 to perform the recording operation on the optical disc 1 (step S219). .

On the other hand, if it is determined that the transmittance has not been switched normally as a result of the determination, the dimming element driving circuit 51 is restarted via the transmittance switching unit 25 (step S217). Steps S211 to S215 are repeated. If the normal operation is performed after the re-operation, the process proceeds to step S218. If the normal operation is not performed, the operation of the optical disc apparatus itself is stopped.

As described above, in the optical disc apparatus according to the present embodiment, it is determined whether the change in the amount of emitted light is normal or not according to the transmittance switching control, and only when it is determined that it is normal. Playback or recording on the optical disc 1 can be performed. Therefore, it is possible to reduce the influence of quantum noise during reproduction, and it is possible to prevent the laser element 11 from being deteriorated during recording.

[0129] Furthermore, in the present embodiment, the driving efficiency is used as a meter instead of the emitted light quantity in the first embodiment, and it is determined whether or not the light control element 16 is operating properly. As a result, the following effects can be obtained.

That is, as described in the background art, the laser power control unit 24 performs feedback control that dynamically follows the drive current to the laser drive circuit 50 with respect to the amount of light emitted from the photodetector 15. On the other hand, in the configuration of the first embodiment, it is necessary to perform a power control hold for holding the drive current to the laser drive circuit 50 at a constant value, and a switch for switching the emitted light amount to the light amount measurement unit 30. 40 was the required configuration.

[0131] In contrast, in the present embodiment, the value of the drive current corresponding to an arbitrary amount of emitted light can be used as the drive efficiency, so that the switch that does not require the power control hold is omitted. can do.

[0132] In the first and second embodiments, the light control element 16 and the light control element drive circuit 51 In the above description, the movable light amount attenuating member having a certain transmittance for transmitting the parallel light after passing through the coupling lens 12 and the driving device thereof have been described as an example. The light control element driving circuit 51 may be a voltage application circuit that applies a voltage to the liquid crystal element. In short, the light control device and the light control device driving unit of the present invention are not limited to specific configurations.

[Embodiment 3]

The configuration and operation of the optical disc apparatus according to the third embodiment will be described with reference to the block configuration of FIG. In FIG. 7, the same components as those in FIGS. 1 and 13 are denoted by the same reference numerals, and detailed description thereof is omitted.

[0134] The optical disc device according to the third embodiment includes a power control unit that controls the drive current of the laser drive unit so that the amount of light emitted to the optical disc is constant based on the output of the light amount detection unit, and a predetermined amount. A transmittance control unit that controls the dimming element driving unit so as to coincide with the target value, and the transmittance control unit uses the output of the light amount detection unit and the target value, and the dimming element driving unit The structure which controls is provided. In the above configuration, the transmittance adjusting unit 36 shown in FIG. 7 corresponds to the transmittance adjusting unit of the present invention.

[0135] The transmittance adjusting unit 36 includes a transmittance switching unit so that the output of the AD converter 21 changes according to the amount of light emitted from the photodetector 15 and the change in transmittance that the transmittance switching unit 25 switches. This is a means to adjust the output of 2-5.

Further, in the present embodiment, the light control element 16 is a liquid crystal element that changes the transmittance steplessly by voltage drive.

[0137] The operation of the optical disk apparatus of the third embodiment as described above will be described, and an embodiment of the control apparatus for the optical disk apparatus of the present invention will be described. However, the basic operation of the optical disc apparatus is the same as that described in the background art and Embodiment 1, and the differences will be mainly described.

[0138] When performing a reproducing operation on the optical disc 1, before this operation, the laser power control unit 24 controls the laser driving circuit 50 so that the laser element emits light with a magnitude greater than a value at which quantum noise does not occur. At the same time, change the transmittance from 100% to 50%. An instruction is issued to the transmittance switching unit 25 so that the output of 1 also changes from 100% to 50%.

When the transmittance switching unit 25 receives a command from the laser power control unit 24, the transmittance switching unit 25 applies an applied voltage corresponding to the transmittance to the light control device 16 that is a liquid crystal device.

[0140] At this time, the AD converter 21 receives the output AD-converted by the AD converter 21 from the photodetector 15 that receives the parallel light that has passed through the light control element 16, and the transmittance adjusting unit 36 receives the AD converter 21. Feedback control is performed to increase or decrease the output of the transmittance switching unit 25 so that the amount of light emitted to the optical disc 1 based on the output of the output becomes the predetermined target value.

[0141] When performing the recording operation, the laser power control unit 24 issues a command to the transmissivity switching unit 25 that changes the transmissivity from 50% to 100%, and the transmissivity is changed to 100%. After that, the laser drive circuit 50 is controlled so that a drive current having a size equal to or smaller than the upper limit at which the laser element 11 operates stably and large enough for recording flows. Similar to the reproduction operation, the transmittance adjusting unit 36 performs feedback control for increasing or decreasing the output of the transmittance switching unit 25 so that the output of the AD converter 21 corresponds to a predetermined target light emission amount.

[0142] As described above, according to the present embodiment, it is possible to adjust the dimming element 16 to a desired transmittance regardless of the initial state and the operation target state of the optical disc apparatus.

[0143] In the above description, the characteristics of the AD change when the output of the force transmittance switching unit 25 is changed discretely, using feedback control that continuously varies the value as an example. 2 or more, and use function approximation calculation such as linear approximation calculation to obtain and set the output of the transmittance switching unit 25 so that the output of the AD converter 21 corresponds to the target output light quantity. You may make it do. In this case, since the output of the transmittance switching unit 25 can be obtained at high speed and with high accuracy, the dimmer 16 can be adjusted to a desired transmittance in a short time.

[0144] The configuration of the third embodiment may be implemented in combination with the first embodiment, and may be operated when a liquid crystal element is used as the light control element 16. In this case, when it is determined in steps S106 and S116 that the operation of the light control element is not normal, there is an advantage that the light control element 16 can be quickly adjusted to a desired transmittance.

Further, the configuration of the third embodiment may be used for initial setting of the transmittance of the light control element 16 in the adjustment at the time of manufacturing the optical disk device. In this case, the optical disk immediately after completion In the recording apparatus, it is possible to obtain an accurate transmittance for the actual operation of recording or reproduction.

[Embodiment 4]

The configuration and operation of the optical disc apparatus according to the fourth embodiment will be described with reference to the block configuration of FIG. In FIG. 8, the same components as those in FIGS. 1, 7, and 13 are denoted by the same reference numerals, and detailed description thereof is omitted.

[0147] In the optical disc apparatus according to the fourth embodiment, the transmittance control unit changes the output of the light detection unit when the drive current of the laser drive unit is changed. As the efficiency, there is a drive efficiency detection unit that detects before and after the operation of the dimming element drive unit, compares the drive efficiency of each of the drive efficiency detection units, compares the comparison results, and the target A configuration for controlling the liquid crystal element driving unit using the value is provided. Instead of the transmittance adjusting unit 36 that operates based on the amount of emitted light, the DSP 20 includes a transmittance adjusting unit 37 that operates based on the driving efficiency used in the second embodiment.

[0148] The transmittance adjustment unit 37 of the present embodiment is the same as that of Embodiment 3 in that the output of the transmittance switching unit 25 is adjusted, but the drive with respect to the emitted light amount detected by the drive efficiency detection unit 31 is performed. It differs in that it operates based on the current drive efficiency.

[0149] According to the optical disc device of the fourth embodiment having such a configuration, the dimming element 16 is desired regardless of the initial state and the operation target state of the optical disc device, as in the third embodiment. The transmittance can be adjusted. Further, when a liquid crystal element is used as the light control element 16 in the second embodiment, the configuration of the present embodiment can be used. In this case, there is an advantage that the dimmer 16 can be quickly adjusted to a desired transmittance when it is determined in steps S207 and S216 that the operation of the dimmer is not normal.

[0150] Similarly to the third embodiment, the configuration of the fourth embodiment may be used for the initial setting of the transmittance of the light control element 16 in the adjustment at the time of manufacturing the optical disc apparatus. In this case, it is possible to obtain an accurate transmissivity for the actual recording or reproduction operation in the optical disc apparatus immediately after completion.

[0151] In Embodiments 3 and 4, a liquid crystal element is used as the light control element 16. In this case, the driving characteristics of the light control element 16 that achieves a predetermined transmittance may change depending on the temperature. In response to this, a temperature sensor 17 is provided in the optical head 10 as in the configuration example shown in FIG. 9, and when the temperature changes, a signal is received from the temperature sensor 17 and the transmittance is adjusted based on this signal. The unit 37 adjusts the transmittance of the light control element 16 again, so that the influence of the change in the characteristics of the light control element 16 due to the temperature can be eliminated. The temperature sensor 17 corresponds to the characteristic change detection unit of the present invention. However, the characteristic of the present invention is not limited to the temperature as long as it can be detected as a signal. It may be a factor.

[0152] Further, the output of the transmittance switching unit 25 of the adjustment result is stored in the memory 25a built in the DSP 20, and when the changed temperature is a temperature adjusted in the past, the past adjustment result is not adjusted and the past adjustment result is not displayed. By using this and changing the transmittance of the light control element 16, the number of adjustments accompanying a temperature change can be reduced. The configuration of the temperature sensor and the memory 25a shown in FIG. 9 may be based on the fourth embodiment, which is based on the third embodiment.

[Embodiment 5]

The configuration and operation of the optical disc apparatus according to the fifth embodiment will be described with reference to the block configuration of FIG. In FIG. 10, the same components as those in FIGS. 1 and 13 are denoted by the same reference numerals, and detailed description thereof is omitted.

[0154] In the optical disc device according to the fifth embodiment, the adjustment unit measures the laser drive values set in the laser drive unit by the power control unit before and after the operation of the dimming element drive unit, respectively. A drive value measurement unit and a light control element state determination unit for comparing the measurement results of the drive value measurement unit and determining the state of the light control element from the comparison result are provided. As shown in FIG. 10, the drive measurement unit 39 corresponds to the drive value measurement unit of the present invention, the memory 33 corresponds to the memory of the present invention, and the dimming element operation determination unit 38 corresponds to the dimming element state of the present invention. It corresponds to a determination unit. The drive measurement unit 39, the memory 33, and the dimming element operation determination unit 38 are built in the DSP 20.

[0155] The drive measurement unit 39 is a means for measuring the laser drive amount of the laser power control unit 24 before and after the transmittance of the light control element 16 is switched by the transmittance switching unit 25, and the memory 33 is the measured laser. It is a means for storing the driving amount. In addition, the light control element operation determination unit 38 This is a means for judging whether or not the laser driving amount stored in the above has changed normally before and after the transmittance is switched.

[0156] The operation of the optical disk apparatus according to the fifth embodiment having the above-described configuration will be described, and an embodiment of the control apparatus for the optical disk apparatus according to the present invention will be described.

[0157] Taking the reproduction operation as an example, the laser power control unit 24 uses a laser that measures a certain amount of emitted light P (for example, 1. OmW) corresponding to the reproduction operation from the signal output from the photodetector 15. A drive value is generated, converted to DA by DA conversion, and output to the laser drive circuit 50.

[0158] In parallel with the above operation, the transmissivity switching unit 25 is configured so that the output of AD conversion 21 is also changed from 100% to 50%. Issue an order to

When the transmittance switching unit 25 receives a command from the laser power control unit 24, the transmittance switching unit 25 causes the light control device driving circuit 51 to operate the light control device 16 so as to correspond to the transmittance. At this time, when the light control element 16 is the light amount attenuation member mechanism exemplified in Embodiments 1 and 2, the light amount attenuation member moves so as to be disposed on the optical path of the parallel light. In the case of the liquid crystal element exemplified in Embodiments 3 and 4, a driving voltage for applying a liquid crystal transmittance of 50% is applied.

[0160] The drive measurement unit 39 includes a laser drive circuit 50 from the laser power control unit 24 as a laser drive amount before and after the light control element 16 is switched from 100% to 50% by the transmittance switching unit 25. Measure each output to and store it in memory 33.

The dimming element operation determination unit 38 determines that the laser drive amount measured by the drive measurement unit 39 and stored in the memory 33 has changed normally before and after switching the transmittance.

FIG. 11 shows an example of the characteristic of the emitted light amount P of the optical head 10 with respect to the drive current i of the laser element 11. The horizontal axis represents the drive current i of the laser element 11, and the vertical axis represents the amount of emitted light P.

[0163] As shown in FIG. 11, when the light control device 16 is operating normally, the laser power control unit 24 controls the transmission light amount P to be a constant value 1. OmW. When 100%, the laser element 11 has a drive current ie of 25 mA ie When the light control element 16 is operated and the transmittance is changed to 50%, the laser element 11 has a drive current of 30 mA if But It ’s going to flow.

Therefore, a value corresponding to the time of reproduction or recording is set as the emitted light quantity P, and it is determined whether or not the driving current value at that time is appropriately changing before and after the change of the transmittance. Therefore, it can be determined whether or not the transmittance switching control by the light control element 16 is normally performed.

[0165] If the emitted light quantity P = 1. OmW is the appropriate light quantity for playback, the drive current will increase from 25 mA to 30 mA if the transmittance is changed from 100% to 50%. In other words, an appropriate change amount is an increase of 5 mA in the laser drive current. Therefore, if the laser drive amount, which is the output from the laser power control unit 24 to the laser drive circuit 50, is equivalent to a 5 mA boost!], The dimming element operation determination unit 38 indicates that the operation of the dimming element 16 is normal. Judgment is made and playback is performed as it is.

[0166] On the other hand, if the laser drive amount does not change by 5 mA, it is determined that the operation of the dimmer 16 is not normal, and the dimmer 16 is operated again to check if the laser drive amount has changed by 5 mA. Check.

[0167] Assuming that the emitted light quantity P = 1. OmW is the appropriate light quantity for recording, when the transmittance is changed from 50% to 100%, the laser drive amount will be reduced by 5mA. Check. In other words, the appropriate amount of change is a decrease in laser drive current of 5 mA. Therefore, if the change in the laser drive amount is reduced by 5 mA, the dimming element operation determination unit 38 determines that the operation of the dimming element 16 is normal and performs recording as it is. On the other hand, when it is determined that the change in the laser drive amount is not the above decrease amount, the dimmer 16 is operated again to determine the change in the laser drive amount. It should be noted that the operation control of the light control element when it is not normal in both the reproduction operation and the recording operation may be performed according to the same flowchart as in the first and second embodiments. If the light control element 16 is a liquid crystal element, the transmittance may be adjusted by the same control as in the third and fourth embodiments.

[0168] As described above, in the optical disc device according to the present embodiment, it is determined whether the change in the drive current is normal or not according to the transmittance switching control, and only when it is determined as normal. Playback or recording on the optical disc 1 can be performed. Therefore, it is possible to reduce the influence of quantum noise during reproduction, and it is possible to prevent the laser element 11 from being deteriorated during recording. [0169] In each of the above embodiments, when it is determined that the change in transmittance is not normal, the light control element 16 is operated again as in Embodiments 1, 2, and 5, or It is assumed that the operation of the laser element 11 is stopped, or that the voltage applied to the light control element 16 is adjusted so that the transmittance matches the target value as in the third and fourth embodiments. In addition, the following measures may be taken.

[0170] During playback operation, control may be performed so that playback is limited to a slower rotational speed than before. In this case, it is possible to prevent a deterioration in reproduction quality due to an increase in quantum noise.

[0171] Also, during the recording operation, the optical disc 1 is recorded only on a medium having a low recording power, or the upper limit of the recording power is lowered in accordance with the transmittance, or the recording rate is limited to a low speed. May be recorded. In this case, it is possible to prevent the drive current exceeding the maximum output power of the laser element 11 from being supplied, and to prevent the laser element 11 from being destroyed.

[0172] In each of the above embodiments, the measurement of the amount of emitted light has been described as being based on a signal directly detected by the photodetector 15 after passing through the light control element 16. Force As shown in Fig. 12, the reflected light detector of the optical disc 1 is also used as the detector 15 for detecting the reproduction signal, and the signal output from the detector 15 is used as the output light amount as it is. Also good. In FIG. 12, 18 is a 1Z4 wavelength plate. The reflected light from the optical disc 1 changes its polarization state by passing through the 1Z4 wavelength plate 18, passes through the polarizing reflector 13, and reaches the photodetector 15.

In the case of this configuration, the amount of emitted light is changed by changing the transmittance of the light control element 16, and the laser power of the laser light applied to the information recording film 2 of the optical disc 1 is changed. Therefore, the laser power control unit 24 records in the information recording film 2 of the optical disc 1 by controlling the amount of emitted light in advance so that the laser power becomes lower than the laser power during reproduction even when the transmittance is changed. It is possible to provide a stable device that does not destroy the stored information with excessive power.

In Embodiments 1, 2, and 5, when it is determined that the light control element 16 does not operate normally, the optical disc apparatus is in an abnormal state after the reproduction or recording operation is stopped. As a configuration to notify the user that. If the optical disk device is built-in or connected to an external device such as a computer, the determination results of the dimming element operation determination units 34, 38, etc. are output to the outside, and software such as a computer OS or control device Display or notification of abnormal condition via display means using monitor screen, light emitting diode, etc., display means using light, or notification means using sound such as speaker, buzzer, etc. To do.

[0175] When the optical disk device is used in a recorder or player that plays or records a moving image, the control unit of the record or player displays the determination result on a screen such as a monitor device such as a TV that displays the moving image. Control to display (being abnormal).

[0176] By notifying the user that the optical disk device is in an abnormal state in this way, the user's excessive operation can be suppressed, the laser element 11 in the optical disk device can be prevented from being damaged, and the device can be repaired. Can be done quickly.

[0177] In each of the above embodiments, the change in the transmittance of the light control element 16 is a reproduction operation or a recording operation for the single-layer optical disc 1 having the information recording film 2 as a single recording layer. The power described as being performed accordingly The scene where the transmittance of the light control element in the optical disc apparatus of the present invention needs to be changed is not limited to this.

[0178] As another example, there is a case where the transmittance is switched according to the type of the optical disc 1. As a specific example, when the single-layer optical disk 1 of each of the above embodiments and a two-layer optical disk formed by stacking two layers of the information recording film 2 are used, the transmittance of the light control element 16 and the light detection The amount of emitted light detected by the device 15 and the laser power as the control value of the laser power control unit 24 have the relationship shown in (Table 1).

(table 1)

[0179] As shown in (Table 1), when a recording or reproducing operation is performed on a single-layer optical disc, It is necessary to change the transmittance of the light control element 16 depending on whether the recording or reproducing operation is performed on the optical disk. During playback, single-layer optical discs have higher recording sensitivity than double-layer optical discs, so it is necessary to reduce the amount of emitted light during playback. Therefore, control is performed to reduce the transmittance of the light control element 16 to 50% while ensuring the minimum amount of emitted light and preventing the generation of quantum noise in the laser element 11. On the other hand, in the case of a multilayer optical disk, since the reflectance is low, it is necessary to increase the amount of emitted light. Therefore, the transmittance of the light control element 16 is controlled to 100%.

[0180] Also, during recording operation, a strong light output is required for both single-layer and double-layer, but in the case of a single-layer optical disc, the transmittance should be the same as 50% during playback. This saves the operation and time required to switch the transmittance. In the case of a two-layer optical disc, the low reflectivity also causes a strong amount of emitted light as in the case of reproduction.

[0181] As described above, when a single-layer or two-layer optical disk is used as the optical disk 1, the transmittance of the light control element 16 needs to be changed according to the type of the disk. In such an optical disc apparatus, it is possible to perform an operation corresponding to the determination result by determining whether or not the transmittance has been changed normally.

[0182] As another example, there is a case where the transmittance is switched according to the reproduction or recording speed on the optical disc 1. It is necessary to increase the transmittance as the reproduction or recording speed to the single-layer optical disc 1 of each of the above embodiments increases. As the speed, the transmittance of the light control element 16 when the speed is 1 ×, 2 ×, and 4 ×, the amount of emitted light detected by the photodetector 15, and the laser power as the control value of the laser power control unit 24 are (Table The relationship is as shown in 2). (Table 2)

[0183] As shown in Table 2, when recording or playback is performed at 1x speed, recording is performed at a higher speed. Alternatively, it is necessary to increase the transmittance of the light control element 16 when performing a reproducing operation. At the time of playback operation, the output light quantity needs to be reduced at 1x speed because the linear velocity is slow. Therefore, control is performed to reduce the transmittance of the light control element 16 to 50% while ensuring the minimum laser power and preventing the generation of quantum noise in the laser element 11. When the speed is increased to 2 × or 4 ×, the linear velocity increases and SZN deteriorates. Therefore, it is necessary to increase the amount of emitted light. Therefore, the transmittance of the light control element 16 is controlled to 70% and 100%, respectively.

[0184] Also, during recording operation, a strong emitted light quantity is required regardless of the speed, but it is necessary to switch the transmittance by maintaining the same transmittance as at the time of reproduction at each speed. Operation and time can be saved.

As described above, when the reproduction or recording speed is changed with respect to the optical disc 1, it is necessary to change the transmittance of the light control element 16 in accordance with the speed. In the disk device, it is possible to determine whether the force has been changed normally and to perform an operation corresponding to the determination result.

[0186] As described above, in the optical disc apparatus, the present invention can be used according to various cases in which the laser power needs to be controlled in response to the change in the amount of light emitted to the optical disc 1.

[0187] Furthermore, in each of the above-described embodiments, the dimming element operation determining units 34, 35, and 38 determine whether or not the transmittance switching control is normally performed by the transmittance switching unit 25. Although the description has been made on the basis of the amount of emitted light corresponding to the set transmittance, the correspondence between the set transmittance and the amount of emitted light detected by the light detector 15 has a predetermined margin that does not match exactly. It may be. For example, after changing from 100% transmittance, when detecting the amount of emitted light corresponding to 50% transmittance, if the detected amount of emitted light is within the range corresponding to 40-60% transmittance, the transmittance The switching unit 25 may be set so that it is determined that switching from 100% transmittance to 50% transmittance is performed normally. When switching from 50% transmittance to 100% transmittance! /, Just give a similar margin! ,.

Further, in each of the above-described embodiments, the power explained by taking the operation of the entire optical disc apparatus as an example. The present invention may be implemented by the DSP 20 alone as a control device of the optical disc apparatus. Industrial applicability

An optical disk control device or the like that is effective in the present invention has an effect of determining whether or not the transmittance is appropriately controlled by the light control element and controlling the operation of the optical disk device based on the result. The present invention can be applied to an optical disk apparatus and an optical disk control apparatus that perform control to converge and irradiate a light beam using an optical head equipped with an optical disk light control element.

Claims

The scope of the claims

[1] a laser element that emits a light beam that irradiates an optical disc, a laser driving unit that supplies a driving current to drive the laser element, a light amount detection unit that detects the light amount of the light beam, and the laser element A control device for an optical disc apparatus, comprising: a light control element that changes a transmittance of the emitted light beam; and a light control element driving unit that drives the light control element,

An optical disc apparatus comprising: an adjustment unit that determines whether or not the dimming element operates normally with respect to the setting of the transmittance control unit, and adjusts the operation of the laser element according to the determination result Control device.

[2] The adjustment unit includes a light amount measurement unit that measures an output of the light amount detection unit before and after the operation of the light control element driving unit, and

The optical disk device control according to claim 1, further comprising: a dimming element state determination unit that compares the measurement results of the light quantity measurement unit and determines the state of the dimming element from the comparison result. apparatus.

3. The control device for an optical disk device according to claim 2, wherein the output current of the laser driving unit is kept constant at least during the operation of the light quantity measuring unit.

[4] The adjustment unit may use the change in the output of the light detection unit when the drive current of the laser drive unit is changed as the drive efficiency of the drive current before the operation of the dimming element drive unit and A drive efficiency detector for detecting each after operation;

2. The optical disk apparatus according to claim 1, further comprising: a dimming element state determination unit that compares the driving efficiencies of the driving efficiency detection units and determines a comparison result power of the dimming element. Control device.

[5] The adjustment unit includes a drive value measurement unit that measures a laser drive value set in the laser drive unit by the power control unit before and after the operation of the dimming element drive unit, and The optical disk apparatus control device according to claim 1, further comprising: a dimming element state determination unit that compares respective measurement results of the drive value measurement unit and determines a state of the dimming element from the comparison result. .

6. The optical disc apparatus according to claim 5, wherein when the drive value measurement unit is operating, the output of the laser drive unit is controlled so as to keep the output of the light detection unit constant. Control device.

[7] The adjustment unit according to claim 5, wherein the adjustment unit adjusts the output of the laser driving unit to be more limited when it is determined that the dimming element operates normally! The control device for the optical disk device according to the item.

[8] The light control element includes a light amount attenuating member having a constant transmittance,

2. The control device for an optical disk device according to claim 1, wherein the light control element driving unit moves the light amount attenuating member on an optical path formed by light emitted from the laser element.

[9] The light control element is a liquid crystal element whose transmittance changes steplessly according to an applied voltage from the light control element driving unit,

When the dimming element state determination unit determines that the dimming element state is normal !, the dimming element state determination unit controls the dimming element driving unit to match the setting of the transmittance control unit. 5. The control device for an optical disk device according to claim 2 or claim 4.

10. The control device for an optical disk device according to claim 1, wherein the adjusting unit prohibits the recording operation of the optical disk when it is determined that the dimming element is not operating normally.

[11] The light according to claim 1, wherein, when it is determined that the dimming element is not operating normally, the adjustment unit stops the operation of the dimming element driving unit and then restarts the operation. Control device for disk devices.

12. The control device for an optical disk device according to claim 11, wherein the dimming element driving unit makes the output of the dimming element driving unit larger in the re-operation than before the re-operation.

13. The control device for an optical disc device according to claim 1, wherein the light amount detection unit detects a light amount of reflected light of a light beam irradiated on the optical disc as the emitted light amount.

14. The control device for an optical disk device according to claim 1, further comprising a memory for holding a measurement value of the light amount of the light beam when the transmittance control unit is changed.

[15] a laser element that emits a light beam for irradiating the optical disc;

A laser drive section for supplying a drive current to drive the laser element;

A light amount detector for detecting the light amount of the light beam;

2. An optical disc apparatus having the control device for an optical disc apparatus according to claim 1, as a power control unit for controlling the drive current of the laser drive unit and a control unit for controlling operations of the dimming element drive unit. .

[16] A laser element that emits a light beam that irradiates an optical disc, a laser drive unit that supplies the drive current to drive the laser element, a light amount detection unit that detects the light amount of the light beam, and the laser element A control method of an optical disc apparatus comprising: a light control element that changes a transmittance of the emitted light beam; and a light control element driving unit that drives the light control element,

An optical disc apparatus control comprising: an adjustment step that determines whether the light control element is operating normally with respect to the setting in the transmittance control step and adjusts the operation of the laser element according to the determination result Method.