JP2009134776A - Optical disc device and optical disc control device - Google Patents

Abstract

When a dimming element does not operate normally, laser power control malfunctions due to a shift in detection of laser power, and data recorded on a laser element or an optical disk is destroyed by an excessive driving current. May end up.
The outputs of the photodetectors for detecting laser power before and after the operation of the light control element are compared with each other, and it is determined whether the light control element has operated normally from the difference in the change in differential efficiency. If it is determined, laser emission is stopped.
[Selection] Figure 1

Description

  According to the present invention, when recording and reproduction is performed on a disc-shaped information carrier (hereinafter referred to as an optical disk) capable of recording information, the control to converge and irradiate a light beam using an optical head equipped with a light control element is stably performed. The present invention relates to an optical disc apparatus to be performed.

  In recent years, there has been a demand for higher-density optical information recording media 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 five times that of a DVD. 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 double recording density by increasing the output of the blue laser in recent years. For example, a BD having two recording layers has a storage capacity about 10 times that of a DVD. However, the optical disk apparatus for recording / reproducing a high-density optical information recording medium using the blue laser described above has a very severe reproduction margin, so that quantum noise of the light source becomes a problem.

  In order to solve this problem, for example, as described in Patent Document 1, the surface power of the optical information recording medium is kept low to prevent degradation of the optical information recording medium or data erasure. There has been proposed an optical head capable of performing high quality reproduction with low noise and low noise. Further, for example, as disclosed in Patent Document 2, an optical disc apparatus that switches the transmittance according to the reproduction power of the optical information recording medium in consideration of the time for switching the transmittance has been proposed.

  The conventional technique of Patent Document 1 will be described with reference to FIG.

  In order to reproduce or record the optical disk 1, the laser light output from the laser element 11 incorporated in the optical head 10 is attenuated in light quantity by the dimmer 16 incorporated in the optical head 10, and the cup incorporated in the optical head 10. The light is collimated by the ring lens 12. 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. The polarization reflector 13 transmits a part of the laser light and detects the amount of emitted light by the photodetector 15 built in the optical head 10.

  The output of the light detector 15 corresponding to the amount of emitted light is AD converted by the AD converter 21 built in the DSP 20 which is a digital signal processor (DSP), and the laser power control unit 24 built in the DSP 20 emits the light. The laser drive value is output to the DA converter 22 built in the DSP 20 so that the amount of light reaches a predetermined level, and the DA converter 22 DA converts the laser drive value and outputs a laser drive signal. The laser drive signal output from the DA converter 22 operates the laser drive circuit 50 to cause a drive current to flow through the laser element 11 so that the laser element 11 emits light so as to have a predetermined amount of emitted light.

  The DSP built-in transmittance switching unit 25 outputs a dimming drive value for switching the transmittance of the dimming element 16 in accordance with the amount of emitted light controlled by the laser control unit to the DA converter 23 built in the DSP for DA conversion. The device 23 DA-converts the dimming drive value and outputs a dimming drive signal. The dimming driving signal output from the DA converter 23 is switched by operating the dimming element driving circuit 51 to pass a driving current through the dimming element 16 and changing the transmittance of the dimming element 16. The transmittance switching unit 25 reduces the transmittance of the light control element 16 so that the quantum noise is reduced when the output light quantity is reproduced, and increases the transmittance when the output light quantity is recorded. Switch.

According to this conventional optical disc apparatus, during reproduction, the output power of the laser element 11 is increased and the amount of light is attenuated by the light control element 16, so that the quantum noise is kept sufficiently low even with the same output power. be able to. Further, at the time of recording, it is possible to perform recording with an emission power sufficient to maintain the recording quality within the range of the maximum output power of the laser element 11 without attenuating the light amount by the light control element 16.
JP 2000-195086 A JP 2004-272949 A

  However, in a head configured to change the transmittance by putting the light control element 16 in and out of the optical path of the laser, the light control element 16 may not operate normally due to the influence of vibration caused by an external force. Further, a head configured to change the transmittance with liquid crystal or the like may not change to a desired transmittance due to a change in characteristics of the liquid crystal or variations in elements. As described above, when the adjustment of the light amount due to the change in the transmittance of the light control element 16 is not normally performed, the light amount is not sufficiently attenuated by the light control element 16 during reproduction, and the reproduction quality is affected by the quantum noise. There was a problem of getting worse. Further, at the time of recording, the laser power control unit 24 operates so as to output the emission power sufficient to maintain the recording quality while the light amount is attenuated by the light control element 16, so that the maximum output power of the laser element 11 is increased. There was a problem in that the laser element 11 was deteriorated due to light emission exceeding that.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an optical disc apparatus that stably performs control to converge and irradiate a light beam using an optical head equipped with a light control element. .

  In the optical disk apparatus according to claim 1 of the present invention, a laser element that emits a light beam, a laser driving unit that supplies a current to the laser element, a light amount detection unit that detects a light amount of the light beam, and a light amount detection unit A power control means for operating the laser drive means to control the power so that the amount of emitted light is constant based on the output, and a light control element for changing the transmittance of the light beam; A light control device driving means for changing the amount of emitted light, and a transmittance changing means for instructing the light control element driving means to change the transmittance of the light control element, further comprising the transmittance A dimming element operation monitoring unit is provided for determining whether or not the dimming element has normally operated with respect to the setting of the changing unit, and for controlling a current supplied to the laser element.

  In the optical disk apparatus according to a second aspect of the present invention, in addition to the constituent elements of the first aspect, the dimming element operation monitoring means outputs the light quantity detecting means before and after the dimming element driving means drives the dimming element. And a dimming element determination unit for determining the state of the dimming element from the measurement result of the light quantity measuring unit.

  In the optical disk apparatus according to a third aspect of the present invention, in addition to the constituent elements of the first aspect, the dimming element operation monitoring means drives the driving efficiency from the output of the light detecting means when the output of the laser driving means is changed. From the measurement result of the driving efficiency measuring means, the driving efficiency measuring means for measuring the output of the driving efficiency detecting means before and after driving the dimming element by the dimming element driving means, and the measurement result of the driving efficiency measuring means, A dimming element determination unit that determines the state of the dimming element is provided.

  In the optical disk apparatus according to a fourth aspect of the present invention, in addition to the constituent elements of the first aspect, the dimming element operation monitoring means includes a dimming element driving means for driving the dimming element and changing an emitted light amount of the light beam. A drive measuring means for measuring the output of the laser drive means before and after driving the light control element by the light control element drive means, and a light control element for determining the state of the light control element from the measurement result of the drive measurement means And determining means.

  In the optical disk apparatus according to claim 5 of the present invention, in addition to the constituent elements of claim 1, the dimming element operation monitoring means operates the dimming element driving means based on the output of the light quantity detection means. And a transmittance adjusting means for changing the transmittance of the light control element.

  According to a sixth aspect of the present invention, in addition to the constituent elements of the first aspect, the dimming element operation monitoring means is driven from the output of the light quantity detecting means when the output of the laser driving means is changed. Drive efficiency detecting means for outputting the efficiency, and transmittance adjusting means for operating the dimming element driving means to change the transmittance of the dimming element based on the output of the driving efficiency detecting means. Features.

  In the optical disk apparatus according to claim 7 of the present invention, in addition to the constituent elements of claim 1, when the dimming element operation monitoring unit is operating, the operation of the power control unit is stopped and the output of the laser driving unit is output. It is characterized in that the current is kept constant.

  In the optical disk apparatus according to an eighth aspect of the present invention, in addition to the constituent elements of the first aspect, when the dimming element operation monitoring unit is operating, the laser drive is performed by changing a control target value of the power control unit. The output of the means is changed.

  In the optical disk apparatus according to a ninth aspect of the present invention, in addition to the constituent elements of the first aspect, the dimming element operation monitoring unit limits the output of the laser driving unit based on the determination result.

  The optical disc apparatus according to claim 10 of the present invention is characterized in that, in addition to the configuration requirements of claim 9, recording operation of the optical disc is prohibited.

  In the optical disk apparatus according to an eleventh aspect of the present invention, in addition to the constituent elements of the first aspect, the dimming element operation monitoring unit operates the dimming element driving unit again based on the determination result. .

  The optical disk apparatus according to a twelfth aspect of the present invention is characterized in that, in addition to the constituent elements of the eleventh aspect, the output of the dimming element driving means when operated again is increased.

  The optical disk apparatus according to claim 13 of the present invention is characterized in that, in addition to the constituent elements of claim 11, the light amount detecting means detects reflected light of the light beam irradiated on the optical disk.

  In the optical disk apparatus according to the fourteenth aspect of the present invention, in addition to the constituent elements of the thirteenth aspect, the power control means controls the emitted light quantity of the light beam to a lower emitted light quantity than when reproducing the optical disk.

  In the optical disk apparatus according to the fifteenth aspect of the present invention, in addition to the constituent elements of the third aspect, the drive efficiency detection means measures the output of the light detection means with the outputs of at least two laser drive means, and performs linear approximation calculation. The drive efficiency is determined.

  In addition to the constituent elements of the eleventh aspect, the optical disc device according to the sixteenth aspect of the present invention further includes a characteristic change detecting unit that detects a change in the characteristic of the light control element and operates the transmittance adjusting unit again. It is characterized by that.

  An optical disk apparatus according to a seventeenth aspect of the present invention is characterized in that, in addition to the constituent elements of the first aspect, a memory is provided for holding a measured value of the light amount of the light beam when the transmittance is changed.

  In the optical disk control device according to the eighteenth aspect of the present invention, the light beam is emitted from the laser element to the dimming element, the transmittance of the dimming element is changed to change the emitted light quantity, and the light beam is detected by the light quantity detector. A control device for an optical disk that controls an optical head that detects the amount of light, a laser driving unit that drives a laser element, a dimming element driving unit that drives the dimming element to change the amount of light emitted from the light beam, and A dimming element operation monitoring unit is provided for determining whether or not the dimming element has normally operated based on a change in transmittance, and for controlling a current supplied to the laser element.

  In the optical disk control device according to claim 19 of the present invention, in addition to the constituent elements of claim 18, the dimming element operation monitoring means is the light quantity detection means before and after driving the dimming element by the dimming element driving means. And a light control element determination means for determining the state of the light control element from the measurement result of the light quantity measurement means.

  In the optical disk control device according to claim 20 of the present invention, in addition to the constituent elements of claim 18, the dimming element operation monitoring means is configured to detect the output of the light detection means when the output of the laser driving means is changed. Drive efficiency detection means for outputting drive efficiency, drive efficiency measurement means for measuring the output of the drive efficiency detection means before and after the light control element is driven by the light control element drive means, and measurement results of the drive efficiency measurement means And a dimming element determination means for determining the state of the dimming element.

  In the optical disk control device according to claim 21 of the present invention, in addition to the constituent elements of claim 18, the dimming element operation monitoring means drives the dimming element to change the emitted light quantity of the light beam. Means for measuring the output of the laser driving means before and after driving the dimming element by the dimming element driving means, and adjusting the state of the dimming element from the measurement result of the driving measuring means. And an optical element determination unit.

  In the optical disk control device according to claim 22 of the present invention, in addition to the constituent elements of claim 18, the dimming element operation monitoring means operates the dimming element driving means based on the output of the light quantity detection means. And a transmittance adjusting means for changing the transmittance of the light control element.

  In the optical disk control device according to claim 23 of the present invention, in addition to the constituent elements of claim 18, the dimming element operation monitoring means outputs the output of the light quantity detection means when the output of the laser driving means is changed. Driving efficiency detecting means for outputting the driving efficiency from, and transmittance adjusting means for operating the dimming element driving means to change the transmittance of the dimming element based on the output of the driving efficiency detecting means. It is characterized by that.

  In the optical disk apparatus according to claim 1 of the present invention, a laser element that emits a light beam, a laser driving unit that supplies a current to the laser element, a light amount detection unit that detects a light amount of the light beam, and a light amount detection unit A power control means for operating the laser drive means to control the power so that the amount of emitted light is constant based on the output, and a light control element for changing the transmittance of the light beam; A light control device driving means for changing the amount of emitted light, and a transmittance changing means for instructing the light control element driving means to change the transmittance of the light control element, further comprising the transmittance Since the dimming element operation monitoring means for determining whether or not the dimming element has normally operated in response to the setting of the changing means and controlling the current supplied to the laser element is provided, Even in a state, it does not destroy the laser element at an excessive emission.

  In the optical disk apparatus according to a second aspect of the present invention, in addition to the constituent elements of the first aspect, the dimming element operation monitoring means outputs the light quantity detecting means before and after the dimming element driving means drives the dimming element. The light amount measuring means for measuring the light intensity and the light adjusting element determining means for determining the state of the light adjusting element from the measurement result of the light amount measuring means, the effect of claim 1 can be realized using a DSP.

  In the optical disk apparatus according to a third aspect of the present invention, in addition to the constituent elements of the first aspect, the dimming element operation monitoring means drives the driving efficiency from the output of the light detecting means when the output of the laser driving means is changed. From the measurement result of the driving efficiency measuring means, the driving efficiency measuring means for measuring the output of the driving efficiency detecting means before and after driving the dimming element by the dimming element driving means, and the measurement result of the driving efficiency measuring means, Since the light control device determining means for determining the state of the light control device is provided, the effect of claim 1 can be realized by using the DSP.

  In the optical disk apparatus according to a fourth aspect of the present invention, in addition to the constituent elements of the first aspect, the dimming element operation monitoring means includes a dimming element driving means for driving the dimming element and changing an emitted light amount of the light beam. A drive measuring means for measuring the output of the laser drive means before and after driving the light control element by the light control element drive means, and a light control element for determining the state of the light control element from the measurement result of the drive measurement means Since the determination means is provided, the effect of claim 1 can be realized using a DSP.

  In the optical disk apparatus according to claim 5 of the present invention, in addition to the constituent elements of claim 1, the dimming element operation monitoring means operates the dimming element driving means based on the output of the light quantity detection means. With the transmittance adjusting means for changing the transmittance of the light control element, the effect of claim 1 can be realized using a DSP.

  According to a sixth aspect of the present invention, in addition to the constituent elements of the first aspect, the dimming element operation monitoring means is driven from the output of the light quantity detecting means when the output of the laser driving means is changed. Since the driving efficiency detecting means for outputting the efficiency and the transmittance adjusting means for changing the transmittance of the dimming element by operating the dimming element driving means based on the output of the driving efficiency detecting means, The effect of claim 1 can be realized using a DSP.

  In the optical disk apparatus according to claim 7 of the present invention, in addition to the constituent elements of claim 1, when the dimming element operation monitoring unit is operating, the operation of the power control unit is stopped and the output of the laser driving unit is output. Since the current is held constant, the effect of claim 1 can be realized only by diverting the photodetector used for power control.

  In the optical disk apparatus according to an eighth aspect of the present invention, in addition to the constituent elements of the first aspect, when the dimming element operation monitoring unit is operating, the laser drive is performed by changing a control target value of the power control unit. Since the output of the means is changed, the effect of claim 1 can be realized only by diverting the photodetector used for power control.

  The optical disk apparatus according to claim 9 of the present invention is characterized in that, in addition to the constituent elements of claim 1, the dimming element operation monitoring means limits the output of the laser driving means based on the determination result. The effect of claim 1 can be realized with a simple configuration.

  In the optical disk device according to the tenth aspect of the present invention, in addition to the constituent elements of the ninth aspect, the recording operation of the optical disk is further prohibited, so that the effect of the ninth aspect can be further ensured.

  In the optical disk apparatus according to an eleventh aspect of the present invention, in addition to the constituent elements of the first aspect, the dimming element operation monitoring unit operates the dimming element driving unit again based on the determination result. Thus, the effect of claim 1 can be realized.

  In the optical disk apparatus according to the twelfth aspect of the present invention, in addition to the constituent elements of the eleventh aspect, the output of the dimming element driving means when operating again is increased. Thus, the effect of claim 11 can be realized.

  In the optical disk apparatus according to the thirteenth aspect of the present invention, in addition to the constituent elements of the eleventh aspect, the light amount detection means detects the reflected light of the light beam irradiated on the optical disk, so the light amount actually irradiated on the optical disk is measured. Thus, the effect of claim 11 can be realized.

  In the optical disk apparatus according to the fourteenth aspect of the present invention, in addition to the constituent elements of the thirteenth aspect, the power control means controls the emitted light quantity of the light beam to a lower emitted light quantity than that during reproduction of the optical disk. While reducing, the effect of Claim 13 can be implement | achieved.

  In the optical disk apparatus according to the fifteenth aspect of the present invention, in addition to the constituent elements of the third aspect, the drive efficiency detection means measures the output of the light detection means with the outputs of at least two laser drive means, and performs linear approximation calculation. Since the driving efficiency is determined, the slope efficiency can be measured at high speed with high accuracy, and the effect of claim 3 can be realized.

  In addition to the constituent elements of the eleventh aspect, the optical disc device according to the sixteenth aspect of the present invention further includes a characteristic change detecting unit that detects a change in the characteristic of the light control element and operates the transmittance adjusting unit again. Therefore, the effect of claim 11 can be realized without repeating the adjustment accompanying the temperature change of the light control element.

  In the optical disk apparatus according to claim 17 of the present invention, in addition to the constituent elements of claim 1, the optical disk apparatus includes a memory that holds a measurement value of the light amount of the light beam when the transmittance is changed. It can be realized using a DSP.

  In the optical disk control device according to the eighteenth aspect of the present invention, the light beam is emitted from the laser element to the dimming element, the transmittance of the dimming element is changed to change the emitted light quantity, and the light beam is detected by the light quantity detector. A control device for an optical disk that controls an optical head that detects the amount of light, a laser driving unit that drives a laser element, a dimming element driving unit that drives the dimming element to change the amount of light emitted from the light beam, and A dimming element built in the optical head is provided with a dimming element operation monitoring means for determining whether the dimming element has operated normally from the change in transmittance and controlling the current supplied to the laser element. Even when the element does not operate, the laser element is not destroyed by excessive light emission.

  In the optical disk control device according to claim 19 of the present invention, in addition to the constituent elements of claim 18, the dimming element operation monitoring means is the light quantity detection means before and after driving the dimming element by the dimming element driving means. Since the light quantity measuring means for measuring the output of the light quantity and the light adjustment element judging means for judging the state of the light adjustment element from the measurement result of the light quantity measurement means, the effect of claim 18 can be realized by the DSP.

  In the optical disk control device according to claim 20 of the present invention, in addition to the constituent elements of claim 18, the dimming element operation monitoring means is configured to detect the output of the light detection means when the output of the laser driving means is changed. Drive efficiency detection means for outputting drive efficiency, drive efficiency measurement means for measuring the output of the drive efficiency detection means before and after the light control element is driven by the light control element drive means, and measurement results of the drive efficiency measurement means Therefore, the light control element determining means for determining the state of the light control element is provided, so that the effect of claim 18 can be realized by the DSP.

  In the optical disk control device according to claim 21 of the present invention, in addition to the constituent elements of claim 18, the dimming element operation monitoring means drives the dimming element to change the emitted light quantity of the light beam. Means for measuring the output of the laser driving means before and after driving the dimming element by the dimming element driving means, and adjusting the state of the dimming element from the measurement result of the driving measuring means. Since the optical element determination means is provided, the effect of claim 18 can be realized by the DSP.

  In the optical disk control device according to claim 22 of the present invention, in addition to the constituent elements of claim 18, the dimming element operation monitoring means operates the dimming element driving means based on the output of the light quantity detection means. And the transmittance adjusting means for changing the transmittance of the light control element, so that the effect of claim 18 can be realized by the DSP.

  In the optical disk control device according to claim 23 of the present invention, in addition to the constituent elements of claim 18, the dimming element operation monitoring means outputs the output of the light quantity detection means when the output of the laser driving means is changed. Driving efficiency detecting means for outputting the driving efficiency from, and transmittance adjusting means for operating the dimming element driving means to change the transmittance of the dimming element based on the output of the driving efficiency detecting means. Therefore, the effect of claim 18 can be realized by the DSP.

  Embodiments of the present invention will be described below.

(Embodiment 1)
The configuration 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.

  In order to reproduce or record the optical disk 1, the laser light output from the laser element 11 incorporated in the optical head 10 is attenuated in light quantity by the dimmer 16 incorporated in the optical head 10, and the cup incorporated in the optical head 10. The light is collimated by the ring lens 12. 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. The polarization reflector 13 transmits a part of the laser light and detects the amount of emitted light by the photodetector 15 built in the optical head 10.

  The output of the light detector 15 corresponding to the emitted light amount is AD converted by the AD converter 21 built in the DSP 20, and the laser power control unit 24 built in the DSP 20 sets the laser drive value so that the emitted light amount becomes a predetermined level. The signal is output to a DA converter 22 built in the DSP 20, and the DA converter 22 DA converts the laser drive value and outputs a laser drive signal. The laser drive signal output from the DA converter 22 operates the laser drive circuit 50 to cause a drive current to flow through the laser element 11 so that the laser element 11 emits light so as to have a predetermined amount of emitted light.

  The DSP built-in transmittance switching unit 25 outputs a dimming drive value for switching the transmittance of the dimming element 16 according to the amount of emitted light controlled by the laser control unit to the DA converter built in the DSP, and the DA converter. 23 converts the dimming driving value from digital to analog and outputs a dimming driving signal. The dimming driving signal output from the DA converter 23 is switched by operating the dimming element driving circuit 51 to pass a driving current through the dimming element 16 and changing the transmittance of the dimming element 16. The transmittance switching unit 25 reduces the transmittance of the light control element 16 so that the quantum noise is reduced when the output light quantity is reproduced, and increases the transmittance when the output light quantity is recorded. Can be switched.

  Here, the optical disk apparatus according to the first embodiment preferably has a configuration in which the light control element 16 is mechanically replaced with a material having a different transmittance on the laser optical path by voltage drive.

  Furthermore, the optical disc apparatus according to the first embodiment incorporates a light quantity measuring unit 30, a memory 33, and a dimming element operation determining unit 34 in the DSP 20. The light amount measuring unit 30 measures the amount of light emitted by the photodetector 15 before and after switching the transmittance of the light control element 16 by the transmittance switching unit 25 and stores it in the memory 33. The dimming element operation determination unit 34 determines that the emitted light amount measured by the light amount measurement unit 30 and stored in the memory 33 has changed normally before and after switching the transmittance.

  In order to suppress the influence of quantum noise during reproduction, for example, when the transmittance is changed from 100% to 50%, it is confirmed whether the amount of emitted light is also changed from 100% to 50%. When the dimming element operation determination unit 34 determines that the change in the amount of emitted light is normal, the reproduction is performed as it is, and when it is determined that the change in the amount of emitted light is not normal, the dimming element 16 is operated again. Confirm that the amount of emitted light has also changed from 100% to 50%. In order to ensure the maximum output power during recording, for example, when the transmittance is changed from 50% to 100%, it is confirmed that the amount of emitted light is changed from 50% to 100%. When the dimming element operation determination unit 34 determines that the change in the emitted light amount is normal, recording is performed as it is, and when it is determined that the change in the emitted light amount is not normal, the dimming element 16 is operated again. Confirm that the amount of emitted light has changed from 50% to 100%.

  In this way, since reproduction and recording are performed when it is determined that the change in the amount of emitted light is normal, reproduction is performed without reducing the influence of quantum noise, so that reproduction quality is not deteriorated. Further, since recording is performed within the range of the maximum emission power of the laser element 11, it is possible to prevent the laser element 11 from being deteriorated.

(Embodiment 2)
The configuration of the optical disc apparatus according to the second embodiment will be described with reference to the block configuration of FIG. In FIG. 2, the same components as those in FIG.

  In order to reproduce or record the optical disk 1, the laser light output from the laser element 11 incorporated in the optical head 10 is attenuated in light quantity by the dimmer 16 incorporated in the optical head 10, and the cup incorporated in the optical head 10. The light is collimated by the ring lens 12. 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. The polarization reflector 13 transmits a part of the laser light and detects the amount of emitted light by the photodetector 15 built in the optical head 10.

  The output of the light detector 15 corresponding to the emitted light amount is AD converted by the AD converter 21 built in the DSP 20, and the laser power control unit 24 built in the DSP 20 sets the laser drive value so that the emitted light amount becomes a predetermined level. The signal is output to a DA converter 22 built in the DSP 20, and the DA converter 22 DA converts the laser drive value and outputs a laser drive signal. The laser drive signal output from the DA converter 22 operates the laser drive circuit 50 to cause a drive current to flow through the laser element 11 so that the laser element 11 emits light so as to have a predetermined amount of emitted light.

  The DSP built-in transmittance switching unit 25 outputs a dimming drive value for switching the transmittance of the dimming element 16 according to the amount of emitted light controlled by the laser control unit to the DA converter built in the DSP, and the DA converter. 23 converts the dimming driving value from digital to analog and outputs a dimming driving signal. The dimming driving signal output from the DA converter 23 is switched by operating the dimming element driving circuit 51 to pass a driving current through the dimming element 16 and changing the transmittance of the dimming element 16. The transmittance switching unit 25 reduces the transmittance of the light control element 16 so that the quantum noise is reduced when the output light quantity is reproduced, and increases the transmittance when the output light quantity is recorded. Switch.

  Here, in the optical disk apparatus according to the second embodiment, it is desirable that the light control element 16 has a structure in which materials having different transmittances are mechanically replaced on the laser light path.

  Furthermore, the optical disk apparatus according to the second embodiment incorporates a drive efficiency detection unit 31, a drive efficiency measurement unit 32, a memory 33, and a dimming element operation determination unit 35 in the DSP 20. The drive efficiency detector 31 measures the output of the photodetector 15 when the drive current of the laser element 11 is changed, and outputs the drive efficiency of the emission power for the drive. For example, if the drive efficiency of the laser element 11 is changed to 30 mA and 40 mA and the output of the photodetector 15 at that time is converted to the output power when the drive efficiency is 1 mW and 2 mW, the drive efficiency is (2 mW− 1 mW) / (40 mA-30 mA) = 0.1 mW / mA. The drive efficiency measurement unit 32 measures the drive efficiency of the drive efficiency detection unit 31 before and after switching the transmittance of the light control element 16 by the transmittance switching unit 25 and stores it in the memory 33. The dimming element operation determining unit 35 determines that the driving efficiency measured by the driving efficiency measuring unit 32 and stored in the memory 33 has changed normally before and after switching the transmittance.

  In order to suppress the influence of quantum noise during reproduction, for example, when the transmittance is changed from 100% to 50%, it is confirmed whether the driving efficiency is also changed from 100% to 50%. When the dimming element operation determination unit 35 determines that the change in drive efficiency is normal, the reproduction is performed as it is, and when the change in drive efficiency is not normal, the dimming element 16 is operated again. Confirm that the amount of emitted light has also changed from 100% to 50%. In order to ensure the maximum output power during recording, for example, when the transmittance is changed from 50% to 100%, it is confirmed that the driving efficiency is changed from 50% to 100%. When the dimming element operation determination unit 35 determines that the change in drive efficiency is normal, recording is performed as it is, and when it is determined that the change in drive efficiency is not normal, the dimming element 16 is operated again. Confirm that the drive efficiency has changed from 50% to 100%.

  Thus, since reproduction and recording are performed when it is determined that the change in drive efficiency is normal, reproduction quality is not deteriorated because reproduction is performed with the influence of quantum noise reduced. Further, since the recording can be performed within the range of the maximum emission power of the laser element 11, it is possible to prevent the laser element 11 from being deteriorated.

(Embodiment 3)
The configuration of the optical disc apparatus according to the third embodiment will be described with reference to the block configuration of FIG. In FIG. 3, the same components as those shown in FIG.

  In order to reproduce or record the optical disk 1, the laser light output from the laser element 11 incorporated in the optical head 10 is attenuated in light quantity by the dimmer 16 incorporated in the optical head 10, and the cup incorporated in the optical head 10. The light is collimated by the ring lens 12. 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. The polarization reflector 13 transmits a part of the laser light and detects the amount of emitted light by the photodetector 15 built in the optical head 10.

  The output of the light detector 15 corresponding to the emitted light amount is AD converted by the AD converter 21 built in the DSP 20, and the laser power control unit 24 built in the DSP 20 sets the laser drive value so that the emitted light amount becomes a predetermined level. The signal is output to a DA converter 22 built in the DSP 20, and the DA converter 22 DA converts the laser drive value and outputs a laser drive signal. The laser drive signal output from the DA converter 22 operates the laser drive circuit 50 to cause a drive current to flow through the laser element 11 so that the laser element 11 emits light so as to have a predetermined amount of emitted light.

  The DSP built-in transmittance switching unit 25 outputs a dimming drive value for switching the transmittance of the dimming element 16 according to the amount of emitted light controlled by the laser control unit to the DA converter built in the DSP, and the DA converter. 23 converts the dimming driving value from digital to analog and outputs a dimming driving signal. The dimming driving signal output from the DA converter 23 is switched by operating the dimming element driving circuit 51 to pass a driving current through the dimming element 16 and changing the transmittance of the dimming element 16. The transmittance switching unit 25 reduces the transmittance of the light control element 16 so that the quantum noise is reduced when the output light quantity is reproduced, and increases the transmittance when the output light quantity is recorded. Switch.

  Here, in the optical disc apparatus according to the third embodiment, it is desirable that the light control element 16 uses a liquid crystal element or the like to change the transmittance steplessly by voltage drive.

  Further, in the optical disc apparatus according to the third embodiment, the DSP 20 includes a transmittance adjusting unit 36. The transmittance adjusting unit 36 adjusts the output of the transmittance switching unit 25 so that the output of the AD converter 21 changes according to the change rate of the transmittance switched by the transmittance switching unit 25. For example, when the transmittance is changed from 100% to 50%, the output of the transmittance switching unit 25 is adjusted so that the output of the AD converter 21 also changes from 100% to 50%. The adjustment of the transmittance by the transmittance adjusting unit gradually increases or decreases the output of the transmittance switching unit 25 until the output of the AD converter 21 reaches a target value. Alternatively, from the output characteristics of the AD converter 21 when the output of the transmittance switching unit 25 is discretely changed, the output of the AD converter 21 becomes a target value by using function approximation such as linear approximation. The output of the correct transmittance switching unit 25 is obtained and set. Since the output of the transmittance switching unit 25 is adjusted so that the output of the AD converter 21 corresponding to the amount of emitted light changes in a predetermined manner, the dimming element 16 can be adjusted to a desired transmittance.

  In this way, since the reproduction and recording are performed by adjusting the transmittance of the light control element 16 so that the change in the amount of emitted light becomes normal, the reproduction quality is deteriorated because the reproduction is performed with the influence of the quantum noise reduced. There is nothing. Further, since recording is performed within the range of the maximum emission power of the laser element 11, it is possible to prevent the laser element 11 from being deteriorated.

(Embodiment 4)
The configuration of the optical disc apparatus according to the fourth embodiment will be described with reference to the block configuration of FIG. In FIG. 4, the same components as those in FIG.

  In order to reproduce or record the optical disk 1, the laser light output from the laser element 11 incorporated in the optical head 10 is attenuated in light quantity by the dimmer 16 incorporated in the optical head 10, and the cup incorporated in the optical head 10. The light is collimated by the ring lens 12. 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. The polarization reflector 13 transmits a part of the laser light and detects the amount of emitted light by the photodetector 15 built in the optical head 10.

  The output of the light detector 15 corresponding to the emitted light amount is AD converted by the AD converter 21 built in the DSP 20, and the laser power control unit 24 built in the DSP 20 sets the laser drive value so that the emitted light amount becomes a predetermined level. The signal is output to a DA converter 22 built in the DSP 20, and the DA converter 22 DA converts the laser drive value and outputs a laser drive signal. The laser drive signal output from the DA converter 22 operates the laser drive circuit 50 to cause a drive current to flow through the laser element 11 so that the laser element 11 emits light so as to have a predetermined amount of emitted light.

  The DSP built-in transmittance switching unit 25 outputs a dimming drive value for switching the transmittance of the dimming element 16 according to the amount of emitted light controlled by the laser control unit to the DA converter built in the DSP, and the DA converter. 23 converts the dimming driving value from digital to analog and outputs a dimming driving signal. The dimming driving signal output from the DA converter 23 is switched by operating the dimming element driving circuit 51 to pass a driving current through the dimming element 16 and changing the transmittance of the dimming element 16. The transmittance switching unit 25 reduces the transmittance of the light control element 16 so that the quantum noise is reduced when the output light quantity is reproduced, and increases the transmittance when the output light quantity is recorded. Switch.

  Here, in the optical disk apparatus according to the fourth embodiment, it is desirable that the light control element 16 uses a liquid crystal element or the like to change the transmittance steplessly by voltage drive.

  Further, in the optical disc apparatus according to the fourth embodiment, the DSP 20 includes a drive efficiency detection unit 31 and a transmittance adjustment unit 37. The drive efficiency detector 31 measures the output of the photodetector 15 when the drive current of the laser element 11 is changed, and outputs the drive efficiency of the emission power for the drive. The transmittance adjusting unit 37 adjusts the output of the transmittance switching unit 25 so that the output of the drive efficiency detecting unit 31 changes according to the change rate of the transmittance switched by the transmittance switching unit 25. For example, when the transmittance is changed from 100% to 50%, the output of the transmittance switching unit 25 is adjusted so that the output of the drive efficiency detector 31 also changes from 100% to 50%. The adjustment of the transmittance by the transmittance adjusting unit gradually increases or decreases the output of the transmittance switching unit 25 until the output of the drive efficiency detecting unit 31 reaches a target value. Alternatively, based on the output characteristics of the drive efficiency detector 31 when the output of the transmittance switching unit 25 is discretely changed, the output of the drive efficiency detector 31 is set to a target value using function approximation such as linear approximation. The output of the transmittance switching unit 25 is determined and set. Since the output of the transmittance switching unit 25 is adjusted so that the drive efficiency detection unit 31 changes a predetermined amount, the dimming element 16 can be adjusted to a desired transmittance.

  Thus, since the reproduction and recording are performed by adjusting the transmittance of the light control element 16 so that the change in driving efficiency becomes normal, the reproduction quality is deteriorated because the reproduction is performed with the influence of the quantum noise reduced. There is nothing. Further, since recording is performed within the range of the maximum emission power of the laser element 11, it is possible to prevent the laser element 11 from being deteriorated.

(Embodiment 5)
The configuration of the optical disc apparatus according to the fifth embodiment will be described with reference to the block configuration of FIG. In FIG. 5, the same components as those shown in FIG.

  In order to reproduce or record the optical disk 1, the laser light output from the laser element 11 incorporated in the optical head 10 is attenuated in light quantity by the dimmer 16 incorporated in the optical head 10, and the cup incorporated in the optical head 10. The light is collimated by the ring lens 12. 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. The polarization reflector 13 transmits a part of the laser light and detects the amount of emitted light by the photodetector 15 built in the optical head 10.

  The output of the light detector 15 corresponding to the emitted light amount is AD converted by the AD converter 21 built in the DSP 20, and the laser power control unit 24 built in the DSP 20 sets the laser drive value so that the emitted light amount becomes a predetermined level. The signal is output to a DA converter 22 built in the DSP 20, and the DA converter 22 DA converts the laser drive value and outputs a laser drive signal. The laser drive signal output from the DA converter 22 operates the laser drive circuit 50 to cause a drive current to flow through the laser element 11 so that the laser element 11 emits light so as to have a predetermined amount of emitted light.

  The DSP built-in transmittance switching unit 25 outputs a dimming drive value for switching the transmittance of the dimming element 16 according to the amount of emitted light controlled by the laser control unit to the DA converter built in the DSP, and the DA converter. 23 converts the dimming driving value from digital to analog and outputs a dimming driving signal. The dimming driving signal output from the DA converter 23 is switched by operating the dimming element driving circuit 51 to pass a driving current through the dimming element 16 and changing the transmittance of the dimming element 16. The transmittance switching unit 25 reduces the transmittance of the light control element 16 so that the quantum noise is reduced when the output light quantity is reproduced, and increases the transmittance when the output light quantity is recorded. Switch.

  Here, in the optical disk apparatus according to the fifth embodiment, it is desirable that the light control element 16 is configured to mechanically replace materials having different transmittances on the laser light path mechanically by voltage drive.

  Furthermore, in the optical disk apparatus according to the fifth embodiment, the DSP 20 includes a drive measurement unit 39, a memory 33, and a dimming element operation determination unit 38. The laser power control unit 24 causes the laser element 11 to emit light through the laser driving circuit 50 so that the output of the photodetector 15 becomes constant when the dimming element 16 is operated. The drive measurement unit 39 measures the output from the laser power control unit 24 to the laser drive circuit 50 before and after switching the transmittance of the light control element 16 by the transmittance switching unit 25 and stores it in the 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. 6 shows an example of the characteristic of the emitted light quantity of the optical head 10 with respect to the drive current of the laser element 11. The horizontal axis represents the drive current of the laser element 11, and the vertical axis represents the amount of emitted light. For example, when the laser power control unit 24 controls the emitted light quantity to be 1 mW, when the transmittance is 100% as shown in FIG. 6, a drive current of 25 mA is supplied to the laser element 11. When the optical element 16 is operated to change the transmittance to 50%, a current of 30 mA flows through the laser element 11. At this time, when the transmittance is changed from 100% to 50% in order to suppress the influence of quantum noise during reproduction, the laser drive current increases from 25 mA to 30 mA. When the light control element operation determination unit 38 determines that the laser drive amount output from the laser power control unit 24 to the laser drive circuit 50 is increased by 5 mA and the operation of the light control element 16 is normal, the light control element operation determination unit 38 When reproduction is performed and it is determined that the laser driving amount does not change by 5 mA and the operation of the dimmer 16 is not normal, the dimmer 16 is operated again to check whether the laser driving amount has changed by 5 mA. . In order to secure the maximum output power at the time of recording, for example, when the transmittance is changed from 50% to 100%, it is confirmed that the laser driving amount is reduced by 5 mA. If the light control element operation determination unit 38 determines that the change in the laser drive amount is normal, the recording is performed as it is, and if it is determined that the change in the laser drive amount is not normal, the light control element 16 is turned on again. A change in the laser driving amount is determined by operating.

  Thus, since reproduction and recording are performed when it is determined that the change in the laser drive amount is normal, reproduction is performed without reducing the influence of quantum noise, so that reproduction quality is not deteriorated. Further, since recording is performed within the range of the maximum emission power of the laser element 11, it is possible to prevent the laser element 11 from being deteriorated.

  In the first, second, third, and fourth embodiments, when the laser control unit controls the driving of the laser element 11 so that the amount of emitted light is constant, the transmittance of the light control element 16 is changed. If the drive control of the laser element 11 is temporarily stopped to fix the drive and the control is resumed after the comparison is performed by changing the transmittance, the comparison of the transmittance can be performed with high accuracy. Can do.

  Further, when it is determined in Embodiments 1, 2, and 5 that the transmittance of light control element 16 has not changed normally, and in Embodiments 3 and 4, the transmittance of light control element 16 cannot be adjusted. In such a case, recording should be prohibited, recording should be limited to media with low recording power, or the upper limit of recording power should be reduced according to the transmittance, or recording should be limited to double speed with low recording power. Thus, it is possible to prevent the laser element 11 from being destroyed exceeding the maximum output power of the laser element 11.

  Further, when it is determined in Embodiments 1, 2, and 5 that the transmittance of light control element 16 has not changed normally, and in Embodiments 3 and 4, the transmittance of light control element 16 cannot be adjusted. In this case, if the reproduction is limited to a slow rotation speed, it is possible to prevent the reproduction quality from deteriorating due to the increase in quantum noise.

  In the first, second, and fifth embodiments, when it is determined that the transmittance of the light control element 16 has not changed normally, the light control element 16 can be driven by operating the light control element again. Therefore, even if the operation is not performed due to the influence of external vibration or the like, the normal operation can be performed by a plurality of executions, and the power consumption in driving the normal dimming element 16 can be suppressed. In addition, when the light control element is operated again, the drive voltage of the light control element 16 is gradually increased, so that the initial drive voltage is further reduced to reduce power consumption and more reliably operate. Can do.

  In the third and fourth embodiments, when the light control element 16 is a liquid crystal element or the like, the driving characteristics of the light control element 16 having a predetermined transmittance may change depending on the temperature. When the temperature changes, the transmittance of the light control element 16 is adjusted again so that the influence of the change in the characteristics of the light control element 16 due to the temperature can be eliminated. Further, the output of the transmittance switching unit 25 as an adjustment result is stored in a memory (not shown) built in the DSP 20, and when the changed temperature is a temperature adjusted in the past, the past adjustment result is not adjusted. By using this and changing the transmittance of the light control element 16, the number of adjustments accompanying a temperature change can be reduced.

  Further, in the first, second, third, fourth, and fifth embodiments, in the case of the optical head 10 configured to detect the laser light before passing through the light control element 16 by the photodetector 15, The output of the reflected light detector (not shown) used for detecting the reproduction signal from the reflected light may be replaced with the output of the light detector 15. Further, at this time, the amount of emitted light is changed by changing the transmittance of the light control element 16, and the power of the laser light irradiated to the information recording film 2 of the optical disc 1 is changed. However, even if the transmittance is changed, the reproduction power is changed. By setting the amount of emitted light to be lower than that, it is possible to provide a stable apparatus that does not destroy information recorded on the information recording film 2 of the optical disc 1 with excessive power.

  In the first, second, and fifth embodiments, when it is determined that the dimming element 16 does not operate normally, the operation is stopped and the user is notified of an abnormal state. When the optical disk device is built in a computer or the like, an abnormal state is displayed on the monitor screen via the OS of the computer. Further, when the optical disc apparatus is a recorder or player that reproduces or records a moving image, an abnormal state is displayed on a screen of a TV or the like that displays the moving image. In this way, by notifying the user that the optical disk device is in an abnormal state, it is possible to suppress the user's unreasonable operation, prevent the laser from being destroyed, and promptly take measures such as repairing the device.

  Further, in Embodiments 1, 2, 3, 4, and 5, switching is performed so that the transmittance is lowered so that the quantum noise is reduced when the amount of emitted light is reproduced, and the transmittance is increased when the amount of emitted light is recording. However, the present invention is not limited to this. For example, a configuration in which the transmittance is changed based on a medium or a layer to be recorded / reproduced or a configuration in which the transmittance is changed based on a double speed for recording / reproduction may be used. .

  INDUSTRIAL APPLICABILITY The present invention can be used for an optical disc apparatus and an optical disc control device that perform control to converge and irradiate a light beam using an optical head equipped with a light control element in order to perform recording and reproduction on an optical disc.

The figure which shows the block configuration in Embodiment 1. The figure which shows the block configuration in Embodiment 2. FIG. 9 shows a block configuration in Embodiment 3. FIG. 10 is a diagram illustrating a block configuration according to the fourth embodiment. FIG. 10 is a diagram illustrating a block configuration according to the fifth embodiment. The figure which shows the characteristic of the emitted light quantity of the optical head with respect to the drive current of the laser element in Embodiment 5 The figure which shows the block configuration in background art

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical disk 2 Information recording film 10 Optical head 11 Laser element 12 Coupling lens 13 Polarization reflecting plate 14 Objective lens 15 Photodetector 16 Light control element 20 DSP
21 AD converter 22 DA converter 23 DA converter 24 Laser power control unit 25 Transmittance switching unit 30 Light quantity measurement unit 31 Drive efficiency detection unit 32 Drive efficiency measurement unit 33 Memory 34 Dimming element operation determination unit 35 Dimming element operation Determination unit 36 Transmittance adjustment unit 37 Transmittance adjustment unit 38 Light control element operation determination unit 39 Drive measurement unit 50 Laser drive circuit 51 Light control element drive circuit

Claims (23)

A laser element for emitting a light beam, a laser driving means for supplying a current to the laser element, a light quantity detecting means for detecting the light quantity of the light beam, and a laser so that the emitted light quantity is constant based on the output of the light quantity detecting means Power control means for operating the drive means and performing power control,
A dimming element that changes the transmittance of the light beam, a dimming element driving unit that drives the dimming element to change the amount of light emitted from the light beam, and the transmission of the dimming element with respect to the dimming element driving unit An optical disc apparatus comprising a transmittance changing means for instructing a rate change,
Further, it is provided with a dimming element operation monitoring means for determining whether or not the dimming element has normally operated with respect to the setting of the transmittance changing means and controlling a current supplied to the laser element. Optical disk device. The dimming element operation monitoring means measures the output of the light quantity detecting means before and after driving the dimming element by the dimming element driving means, and from the measurement result of the light quantity measuring means, 2. The optical disc apparatus according to claim 1, further comprising a dimming element determination unit for determining a state. The dimming element operation monitoring means drives the dimming element by the driving efficiency detecting means for outputting the driving efficiency from the output of the light detecting means when the output of the laser driving means is changed, and the dimming element driving means. Driving efficiency measuring means for measuring the output of the driving efficiency detecting means before and after, and a dimming element determining means for determining the state of the dimming element from the measurement result of the driving efficiency measuring means, The optical disc apparatus according to claim 1. The dimming element operation monitoring means includes a dimming element driving means for driving the dimming element to change the amount of light emitted from the light beam, and a laser driving means before and after driving the dimming element by the dimming element driving means. 2. The optical disc apparatus according to claim 1, further comprising: a drive measuring unit that measures an output; and a dimming element determination unit that determines a state of the dimming element from a measurement result of the drive measuring unit. The dimming element operation monitoring means includes a transmittance adjusting means for operating the dimming element driving means to change the transmittance of the dimming element based on the output of the light amount detecting means. The optical disc apparatus according to claim 1. The dimming element operation monitoring means is based on the drive efficiency detection means for outputting the drive efficiency from the output of the light amount detection means when the output of the laser drive means is changed, and the output of the drive efficiency detection means, 2. The optical disk apparatus according to claim 1, further comprising transmittance adjusting means for operating the light adjusting element driving means to change the transmittance of the light adjusting element. 2. The optical disk apparatus according to claim 1, wherein when the dimming element operation monitoring means is operating, the operation of the power control means is stopped and the output current of the laser driving means is kept constant. 2. The optical disk apparatus according to claim 1, wherein when the dimming element operation monitoring means is operating, the control target value of the power control means is changed to change the output of the laser driving means. 2. The optical disk apparatus according to claim 1, wherein the dimming element operation monitoring unit limits the output of the laser driving unit based on the determination result. 10. The optical disk apparatus according to claim 9, further for prohibiting an optical disk recording operation. 2. The optical disc apparatus according to claim 1, wherein the dimming element operation monitoring unit operates the dimming element driving unit again based on the determination result. 12. The optical disc apparatus according to claim 11, further comprising increasing the output of the dimming element driving means when operating again. 12. The optical disc apparatus according to claim 11, wherein the light amount detecting means detects reflected light of the light beam irradiated on the optical disc. 14. The optical disk apparatus according to claim 13, wherein the power control means controls the emitted light quantity of the light beam to a lower emitted light quantity than when reproducing the optical disk. 4. The optical disk apparatus according to claim 3, wherein the drive efficiency detection means measures the output of the light detection means with the outputs of at least two laser drive means, and determines the drive efficiency by linear approximation calculation. 12. The optical disc apparatus according to claim 11, further comprising characteristic change detecting means for detecting that the characteristic of the light control element has changed and operating the transmittance adjusting means again. 2. The optical disk apparatus according to claim 1, further comprising a memory for holding a measured value of the light amount of the light beam when the transmittance is changed. An optical disk control device that controls an optical head that emits a light beam from a laser element to a light adjusting element, changes the transmittance of the light adjusting element to change the amount of emitted light, and detects the light amount of the light beam with a light amount detector And
A laser driving means for driving the laser element; a dimming element driving means for driving the dimming element to change the amount of light emitted from the light beam;
The optical disc control further comprises a dimming element operation monitoring means for determining whether the dimming element has operated normally from the change in transmittance and controlling a current supplied to the laser element. apparatus. The dimming element operation monitoring means measures the output of the light quantity detecting means before and after driving the dimming element by the dimming element driving means, and from the measurement result of the light quantity measuring means, 19. The optical disk control device according to claim 18, further comprising a light control element determination means for determining the state. The dimming element operation monitoring means drives the dimming element by the driving efficiency detecting means for outputting the driving efficiency from the output of the light detecting means when the output of the laser driving means is changed, and the dimming element driving means. Driving efficiency measuring means for measuring the output of the driving efficiency detecting means before and after, and a dimming element determining means for determining the state of the dimming element from the measurement result of the driving efficiency measuring means, The optical disk control device according to claim 18. The dimming element operation monitoring means includes a dimming element driving means for driving the dimming element to change the amount of light emitted from the light beam, and a laser driving means before and after driving the dimming element by the dimming element driving means. 19. The optical disk control device according to claim 18, further comprising: drive measurement means for measuring an output; and light adjustment element determination means for determining the state of the light adjustment element from the measurement result of the drive measurement means. The dimming element operation monitoring means includes a transmittance adjusting means for operating the dimming element driving means to change the transmittance of the dimming element based on the output of the light amount detecting means. The optical disk control device according to claim 18. The dimming element operation monitoring means is based on the drive efficiency detection means for outputting the drive efficiency from the output of the light amount detection means when the output of the laser drive means is changed, and the output of the drive efficiency detection means, 19. The optical disk control device according to claim 18, further comprising transmittance adjusting means for operating the light adjusting element driving means to change the transmittance of the light adjusting element.

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