JP2003257072A - Optical disk drive - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical disk drive which, by varying transmissivity in accordance with the type of an optical disk, makes the output power of a light source high power fully reducing quantizing noise, which at the same time enables the irradiation power to carry out reproduction at low power causing no deterioration of a recording layer nor erasure of data, and which in addition facilitates detection of a change in transmissivity without using a dedicated sensor. <P>SOLUTION: The optical disk drive is equipped with the light source 101 and an optical element 102 that can vary the transmissivity of a light beam arranged between the light source 101 and an emission power detecting means. The device realizes an improved reproduction state by varying the transmissivity in accordance with the type of the optical disk 108. Further, the device has the ability to detect a change in the transmissivity by detecting a change in the output of a light source control signal. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk device for recording a signal on an optical disk or reproducing a signal recorded on an optical disk by using a light beam, and particularly to a good condition with low noise during reproduction. Is realized.

[0002]

2. Description of the Related Art In recent years, a digital versatile disk (hereinafter referred to as a DVD) has been attracting attention as a high density optical disk capable of recording a large amount of digital information. However, with the increase in the capacity of information, realization of a higher density optical disc is required. Here, in order to achieve higher density recording than DVD, it is necessary to record a mark smaller than DVD on the recording layer. Therefore, the wavelength of the light source is short and the numerical aperture of the objective lens (hereinafter, It is necessary to increase the (NA). For example, in a DVD, a laser having a wavelength of 660 nm is used as a light source and a lens having an NA of 0.6 is used as an objective lens. However, a blue laser having a wavelength of 405 nm is used as a light source and an objective lens having an NA of 0.85 is used. A recording capacity of about 5 times can be achieved. Further, in order to obtain a higher recording capacity than that of a so-called single-layer disc having one recording layer due to the recent increase in output power of a blue laser, a multi-layer disc having a plurality of recording layers has been developed. For example, if a disc having two recording layers is realized, the storage capacity will be about 10 times that of a DVD.

[0003]

However, in the conventional high-density optical disk device, various stress margins at the time of reproduction are stricter than those of the DVD, so that the quantization noise of the blue laser as the light source becomes a problem. Due to the characteristics of the semiconductor laser that is the light source, this quantization noise can be suppressed to a low level by increasing the output laser power. However, when the output laser power is increased, the power of the laser beam that is focused and irradiated to the recording layer (hereinafter referred to as irradiation power). ) Increases, causing deterioration of the recording layer and erasing of data.

The present invention has been made in order to solve the above-mentioned problems. By suppressing the irradiation power to a low level, deterioration of the recording layer and erasing of data can be prevented, and at the same time, the output power is increased to increase the quantization noise of the semiconductor laser. Since it is possible to suppress the noise, it is possible to realize a good reproduction state with low noise by using the optical disk device of the present invention.

[0005]

The optical disk device of the present invention comprises a light source for generating a light beam, an irradiation power detecting means for detecting the power of the light beam applied to the optical disk by the light source, and the irradiation power detecting means. A light beam power control means for driving the light source so that the output of the light source becomes a predetermined value, a power increasing / decreasing means for attenuating or amplifying the power of the light beam while the light source reaches the optical disc, And an increase / decrease detecting unit for detecting that the power of the light beam has been increased / decreased by the increasing / decreasing unit.

In the optical disk device of the present invention, the power increasing / decreasing means comprises a transmitted light quantity changing means capable of varying the transmittance, and a transmitted light quantity controlling means changing the transmittance of the transmitted light quantity changing means, and the increase / decrease detecting means is the above-mentioned It is characterized by further comprising transmittance change detection means for detecting that the transmittance of the transmitted light amount changing means has changed.

In the optical disk device of the present invention, the transmittance change detecting means detects the transmittance change by comparing the detection result by the irradiation power detecting means with the drive value of the light source by the light beam power control means. It is characterized by

The optical disk device of the present invention comprises a reproduction jitter detecting means for detecting the jitter of the reproduction signal of the data recorded on the optical disk, and the transmittance change detecting means detects the reproduction jitter value detected by the reproduction jitter detecting means. It is characterized in that a change in transmittance is detected by the change.

In the optical disk device of the present invention, when the transmittance change detecting means determines that the transmittance does not change when the transmittance of the transmitted light amount changing means is changed, the transmitted light quantity controlling means It is characterized in that the transmittance is changed again by.

The optical disk device of the present invention comprises focus error detecting means for detecting a deviation between the focus and the information surface of the light beam convergently irradiated on the information surface of the optical disk, and the light beam convergently irradiated on the information surface of the optical disk and the information. And a tracking error detecting means for detecting the deviation of the track on the surface,
When the transmittance of the transmitted light amount changing means is changed, the focus error detecting means and / or the offset of the output signal of the tracking error detecting means is changed.

The optical disk device of the present invention is constructed such that the offset of the output signal of the focus error detecting means and / or the tracking error detecting means is continuously changed according to the change of the drive value of the light source. Is characterized by.

The optical disk device of the present invention comprises focus control means for controlling the focus of the converged and irradiated light beam so as to be positioned on the information surface of the optical disk, and the converged and irradiated light beam on the track of the optical disk. Tracking control means for controlling the transmission light quantity changing means to change the transmittance of the transmitted light quantity changing means in a state in which the focus control means or the focus control means and the tracking control means are operated. It is characterized in that it is configured as follows.

The optical disk device of the present invention is characterized in that the transmitted light amount control means changes the transmittance stepwise or continuously.

In the optical disk device of the present invention, a light source for generating a light beam, an irradiation power detection means for detecting the power of the light beam applied to the optical disk by the light source, and an output of the irradiation power detection means have a predetermined value. Light beam power control means for driving the light source so that the power of the light beam can be attenuated or amplified while reaching the optical disc from the light source, and the light beam power control means The output of the reproduction jitter detection means includes an increase / decrease detection means for detecting an increase / decrease in power, and a reproduction jitter detection means for detecting a jitter of a reproduction signal of information recorded on the disk based on reflected light from the optical disk. The power increasing / decreasing means is controlled based on the above.

In the optical disk device of the present invention, the power increasing / decreasing means comprises a transmitted light quantity changing means capable of varying the transmittance and a transmitted light quantity controlling means for changing the transmittance of the transmitted light quantity changing means, and the increase / decrease detecting means comprises The change in the transmittance of the transmitted light amount changing means is configured to be detected by comparing the detection result by the irradiation power detecting means and the drive value of the light source by the light beam power control means, and the transmitted light amount changing means is The transmittance is changed based on the output of the reproduction jitter detecting means.

The optical disc device of the present invention is characterized in that the transmitted light amount control means is configured to reduce the transmittance of the transmitted light amount changing means until the output value of the reproduction jitter detection means falls below a predetermined value.

The optical disk device of the present invention is characterized in that the minimum value of the transmittance of the transmitted light amount changing means is set so that the level of the drive value of the light source is equal to or less than the rated value of the light source.

In the optical disk device of the present invention, when the transmittance of the transmitted light quantity changing means reaches the set minimum value and the output value of the reproducing jitter detecting means does not fall below the predetermined value, the reproducing operation is performed. It is characterized in that it is configured to stop.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 is a block diagram showing the configuration of an optical disk device according to Embodiment 1. In FIG. 1, a light source 101 is a GaN-based blue light emitting semiconductor laser element, which is a light source for outputting coherent light for recording and reproduction to and from a recording layer of an optical disc 108, and has a predetermined light amount according to a signal from a light source driving unit 115. Output a light beam of. The light beam attenuation optical element 102 is an optical filter, and is an optical element that is mechanically moved in and out by a signal from the optical element driving unit 116. The polarization beam splitter 103 converts the linearly polarized light emitted from the light source 101 into 1
It is an optical element that transmits 100% and reflects 100% of the linearly polarized light that is orthogonal to the linearly polarized light emitted from the light source 101.

The collimator lens 104 is a lens for converting the divergent light emitted from the light source 101 into parallel light.
The quarter-wave plate 105 is an optical element that converts the polarization of transmitted light from circularly polarized light to linearly polarized light, or from linearly polarized light to circularly polarized light. The half mirror 106 is an optical element that reflects and transmits incident light, and reflects 90% of the light beam and transmits 10% thereof. The objective lens 107 is a lens that focuses a light beam on the recording layer of the optical disc 108.

The first condenser lens 109 is a lens for condensing the light beam transmitted through the half mirror 106 on the first detector 110. The second condenser lens 111 is a lens that condenses the light beam reflected by the optical disc 108 on the second detector 112. The first and second detectors 110 and 112 are elements that convert the received light into electric signals. The reflectance detection unit 113 is an element for discriminating the optical disc based on all output signals from the second detector. A microcomputer (hereinafter referred to as a microcomputer) 114 is an element that controls the optical disk device.

The focus error signal (hereinafter referred to as FE signal) generating section 117 is a circuit for generating an FE signal indicating the converged state of the light beam converged and irradiated on the optical disk 108. The focus actuator 118 is an element that moves the light beam passing through the objective lens 107 in the optical axis direction. The focus drive unit 119 is a circuit that outputs a focus actuator drive signal based on the focus control signal output from the focus control unit 120. The focus control unit 120 includes the FE signal generation unit 11
7 is a circuit that outputs a focus control signal based on the error signal that is output from 7.

The tracking error signal (hereinafter referred to as TE signal) generating section 121 is a circuit for generating a TE signal indicating the irradiation position of the light beam converged and irradiated on the optical disk 108. The tracking actuator 122 is an element that moves the objective lens 107 in the radial direction of the optical disc 108. The tracking drive unit 123 is a circuit that outputs a tracking actuator drive signal based on the tracking control signal output from the tracking control unit 124. The tracking control unit 124 is a circuit that outputs a tracking control signal based on the error signal output from the TE signal generation unit 121. The reproduction jitter detector 125 is an element that detects the jitter of the reproduction signal.

The irradiation power detection means is the first detector 110, and the light beam power control means is the first detector 110.
Detector 110, microcomputer 114, and light source driver 11
5, the transmitted light quantity changing means is composed of the light beam attenuation optical element 102, the transmitted light quantity control means is composed of the microcomputer 114 and the optical element drive section 116, and the reproduction jitter detecting means is , Playback jitter detector 1
25, the focus error detection unit is the FE signal generation unit 117, and the tracking error detection unit is T
The E signal generation unit 121, and the focus control unit is F
E signal generation unit 117 and focus actuator 118
And a focus drive unit 119 and a focus control unit 120, and the tracking control unit includes a TE signal generation unit 121, a tracking actuator 122, a tracking drive unit 123, and a tracking control unit 124.

The operation of the optical disk device configured as described above will be described with reference to FIG. The linearly polarized light emitted from the light source 101 enters the light beam attenuation optical element 102. When the optical disc 108 is a single-layer disc, the optical beam attenuating optical element 102 is mechanically inserted into the optical path by a signal from the optical element driving unit 116, and the optical beam whose light amount is about half is transmitted. On the other hand, when the optical disc 108 is a two-layer disc, the light beam attenuating optical element 102 is mechanically emitted from the optical path, and the light beam is transmitted without reducing the light amount. The light beam transmitted through the light beam attenuating optical element 102 is reflected by the polarization beam splitter 1
It is incident on 03.

The light beam that has passed through the polarization beam splitter 103 is incident on a collimator lens 104 and is collimated by the collimator lens 104. The light beam that has passed through the collimator lens 104 is circularly polarized by the quarter-wave plate 105, and approximately 90% is converted by the half mirror 106.
The light beam having the light amount of is reflected, and the light beam having the light amount of about 10% is transmitted through the half mirror 106. Half mirror 10
The light beam reflected by 6 is incident on the objective lens 107 and is converged and irradiated on the optical disc 108. The light beam that has passed through the half mirror 106 has the first condenser lens 10
9 and is incident on the first detector 110.
The light beam incident on the first detector 110 is converted into an electric signal. Therefore, the output of the first detector 110 becomes an electric signal for monitoring the light quantity of the light beam emitted from the light source 101. The microcomputer 114 outputs a light amount control signal based on the output of the first detector 110 so that the light source 101 outputs a predetermined light amount. Microcomputer 1
The light amount control signal output from 14 is input to the light source driving unit 115, and the light source 101 is controlled to output a predetermined light amount.

Next, the light beam reflected from the optical disk 108 passes through the objective lens 107 and the half mirror 1
06, transmitted through the quarter-wave plate 105, and the light source 1
The linearly polarized light orthogonal to the light beam emitted from 01 is transmitted through the collimator lens 104 and reflected by the polarization beam splitter 103. The light beam reflected by the polarization beam splitter 103 is reflected by the second condenser lens 11
The light is condensed by 1 and is incident on the second detector 112. The light beam incident on the second detector 112 is converted into an electric signal, and the reflectance detection unit 113, the FE signal generation unit 117, the TE signal generation unit 121, and the reproduction jitter detection unit 1 are converted.
25 is output.

The FE signal generator 117 generates an FE signal indicating the converged state of the light beam converged and irradiated on the optical disc 108 by the astigmatism method, for example, based on the signal from the second detector 112, and the focus is obtained. Control unit 120
Output to. FE input to the focus control unit 120
The signal is, for example, a digital signal processor (hereinafter,
It is output to the focus drive unit 119 as a focus drive signal after passing through a phase compensation circuit and a low frequency compensation circuit configured by a digital filter by a DSP). The focus drive signal input to the focus drive unit 119 is amplified and output to the focus actuator 118. Therefore, the position of the objective lens 107 is controlled in the optical axis direction of the lens so that the converged state of the light beam converged and irradiated on the optical disk 108 is always in a predetermined converged state.

The TE signal generator 121 also generates a TE signal indicating the irradiation position of the light beam by, for example, the push-pull method based on the signal from the second detector 112, and outputs it to the tracking controller 124. The TE signal input to the tracking controller 124 is, for example, a DSP signal.
Phase compensation circuit composed of a digital filter according to
It passes through the low-frequency compensation circuit and is output to the tracking drive unit 123 as a tracking drive signal. The tracking drive signal input to the tracking drive unit 123 is amplified and output to the tracking actuator 122. Therefore, the position of the objective lens 107 is adjusted so that the light beam converged and irradiated on the optical disk 108 is irradiated on a desired track on the optical disk 108.
Is controlled in the radial direction.

The reproduction jitter detecting section 125 detects the jitter of the reproduction signal based on the signal from the second detector 112 and outputs it to the microcomputer 114. Further, the reflectance detection unit 113 determines the type of the optical disc 108 based on all the output signals from the second detector 112, and outputs a signal according to the determination result to the microcomputer 114. The microcomputer 114 determines whether the optical disc 108 is a single-layer disc or a double-layer disc based on the signal output from the reflectance detection unit 113, and the optical element drive unit 116.
The optical element drive signal is output to. The details of the determination method will be described later. The optical element drive signal input to the optical element drive unit 116 is amplified to mechanically move the optical beam attenuating optical element 102 in and out of the optical path.

Now, a method of discriminating the optical disk 108 by the microcomputer 114 will be described. First, the types of the optical disc 108, that is, the single-layer disc and the double-layer disc will be described with reference to FIG. FIG. 2 is a schematic diagram showing the structure of a single-layer disc and a double-layer disc. As shown in FIG. 2, the single-layer disc is an optical disc having a single recording layer, and the double-layer disc is different from the first recording layer (hereinafter referred to as the L0 layer) near the objective lens and the L0 layer. This is an optical disc having a second recording layer (hereinafter referred to as the L1 layer) far from the objective lens, that is, two recording layers. Double layer L1
Data recording / reproduction is performed on the layer with a light beam that has passed through the L0 layer.

In the present embodiment, the irradiation power for reproduction (hereinafter referred to as reproduction power) is 0.4 mW and the irradiation power for recording (hereinafter referred to as recording power) is 6 mW for a single-layer disc. For the layer disc, the reproducing power was set to 0.8 mW and the recording power was set to 12 mW. The reproduction and recording power of the double-layer disc is twice as high as that of the single-layer disc.
This is because the transmittance of the 0th layer is set to about 50%.

Next, the optical disc 1 is made by the microcomputer 114.
A method for determining whether 08 is a single-layer disc or a dual-layer disc will be described. The output power of the light source 101 is controlled to 1.2 mW by the microcomputer 114 in advance,
The light beam attenuation optical element 102 is assumed to be emitted from the optical path. In this setting, the irradiation power on the objective lens 107 is about 0.3 mW, which is equal to that of the optical disk 10.
When 8 is a single-layer disc, the reproduction allowable irradiation power is 0.4 mW or less, so that even if the optical disc 108 is a single-layer disc or a double-layer disc, the recording layer is not deteriorated and data is erased. .

Under the above settings, the light beam convergently irradiated as described above is made to follow the track of the optical disc 108, and the reflected light from the optical disc 108 is received by the second detector 112. As described above, the second detector 112 converts the incident light beam into an electric signal and outputs the signal to the reflectance detection unit 113. Reflectance detection unit 11
In No. 3, a comparator (not shown) compares all output signal output voltages from the second detector 112 with a preset reference voltage to output a signal corresponding to the type of the optical disc 108 to the microcomputer 114. .

Here, the reference voltage is 1 for the optical disk 108.
The signal output voltage of the second detector 112 obtained by the reflected light in the case of a layer disc and the optical disc 108 is 2
It is set to an intermediate value of the signal output voltage obtained when the disc is a layer disc. Therefore, the second detector 112
By comparing the signal output voltage from the optical disc and the reference voltage with a comparator, a high-level signal output is obtained when the optical disc 108 is a single-layer disc, and a low-level signal output is obtained when the optical disc 108 is a double-layer disc. . That is, the microcomputer 114 can determine whether the optical disc 108 is a single-layer disc or a double-layer disc by determining whether the signal output from the reflectance detection unit 113 is at a high level or a low level.

With the above configuration, after determining whether the optical disc 108 is a single-layer disc or a double-layer disc, the optical beam attenuating optical element 102 is placed in the optical path only when the optical disc 108 is a single-layer disc. It is possible to reduce the transmittance from the light source by about half. Therefore, for both the single-layer disc and the double-layer disc, at the time of reproduction, the output power of the light source is set to a high power so that the quantization noise is sufficiently low, and the irradiation power is set to a low power that does not cause deterioration of the recording layer or data erasure. You can

Furthermore, during recording on a single-layer disc, the output power of the light source is set to a high power so that the quantization noise is sufficiently low. By taking it out from the inside, it is possible to record in a state where the quantization noise is low.

In the switching of the light beam attenuating optical element 102 described above, the light beam attenuating optical element 102 is moved in and out by changing the position of the light beam attenuating optical element 102 with respect to the optical path by using an actuator (not shown). Can be achieved with. In this case, if the sensitivity of the actuator to be used becomes lower than the assumed sensitivity due to temperature change, temporal change, etc., the optical beam drive optical signal output from the microcomputer 114 does not cause the optical beam attenuation optical element 102 to reach the assumed position. This means that the light beam attenuation optical element 102 has not been switched even though the switching operation has been performed, and it goes without saying that a reliable switching operation is required. Therefore, it is necessary to judge whether the switching operation of the light beam attenuation optical element 102 is completed.

The state in which the switching of the light beam attenuating optical element 102 is completed is a state in which the transmittance has reached a predetermined value. Therefore, if a change in the transmittance due to the switching of the optical beam attenuating optical element 102 can be detected, the switching operation is performed. You can judge whether or not Therefore, in the following, a method for detecting transmittance change by the transmittance change detecting means of the present invention will be described with reference to FIG.

FIG. 3 is a characteristic diagram showing changes in the irradiation power of the objective lens 107, the output power of the light source 101, and the output of the light amount control signal output from the microcomputer 114 before and after the switching of the light beam attenuation optical element 102. Is. In FIG. 3, the optical beam attenuation optical element 1 is initially shown.
02 is emitted from the optical path. At this time, for example, if the irradiation power in the objective lens 107 is maintained at about 0.3 mW by the light beam power control means, the output power of the light source 101 is controlled at about 1.2 mW.

Thereafter, at time Tf, the transmittance is 50%.
It is assumed that the light beam attenuating optical element 102 is inserted in the optical path. After the light beam attenuating optical element 102 is inserted at the time Tf, in the steady state, the light beam power control means keeps the irradiation power unchanged at about 0.3 mW. At this time, the output power of the light source 101 is doubled to about 2.4 mW. The output power of the light source 101 corresponds to the light amount control signal output from the microcomputer 114.
The light amount control signal output from the light source driving unit 115 is about 2 as compared with that before the light beam attenuation optical element 102 is inserted.
Is doubled.

As described above, since the light beam power control means changes the light amount control signal output in response to the change in the transmittance, the microcomputer 114 monitors the light amount control signal output to change the transmittance. It becomes possible to detect.

The above is the method for detecting the change in the transmittance using the light amount control signal output.
The change in transmittance can be similarly detected by using the reproduction jitter detected in. The detection method will be described below. First, reproduction jitter and quantization noise will be described with reference to FIG. FIG. 4 shows a mark train recorded on the optical disc 108, a reproduction signal detected by reproducing the mark train, and a binarized reproduction signal obtained by binarizing the reproduction signal at a zero cross point. It is a waveform diagram.

The reproduction jitter is a value representing the edge shift of the recorded mark and the edge of the binarized reproduction signal. The lower the reproduction jitter is, the smaller the shift is. Therefore, it can be said that the reproduction state is good. FIG. 4A shows an ideal state, in which case there is no reproduction jitter. On the other hand, FIG. 4B shows a state in which noise is included in the reproduction signal. In this case, since the reproduction signal has a width due to noise, the edge of the binarized reproduction signal also has a width, and this becomes reproduction jitter. In the presence of semiconductor laser quantization noise,
Since noise enters the reproduction signal and the state becomes (b),
The reproduction noise increases as the quantization noise increases. As described above, the quantization noise and the reproduction jitter are related.

Next, a method of detecting a change in transmittance using reproduction jitter will be described. FIG. 5 is a characteristic diagram showing how the irradiation power of the objective lens 107, the output power of the light source 101, and the reproduction jitter value change before and after the switching of the light beam attenuation optical element 102. In FIG.
Initially, the light beam attenuation optical element 102 is assumed to come out of the optical path. At this time, the irradiation power at the objective lens 107 is set to about 0.
If it is maintained at 3 mW, the output power of the light source 101 is controlled to about 1.2 mW.

Thereafter, at time Tf, the transmittance is 50%.
It is assumed that the light beam attenuating optical element 102 is inserted in the optical path. After the light beam attenuating optical element 102 is inserted at the time Tf, in the steady state, the light beam power control means keeps the irradiation power unchanged at about 0.3 mW. At this time, the output power of the light source 101 is doubled to about 2.4 mW. Since the semiconductor laser which is the light source 101 has a noise characteristic that the quantization noise decreases as the output power increases, the output power increases about twice as much as the reproduction jitter before insertion of the light beam attenuation optical element 102. The reproduction jitter after insertion is low.

As described above, since the reproduction jitter changes with the change in the transmittance, it is possible to detect the change in the transmittance by monitoring the reproduction jitter detected by the reproduction jitter detector 125. Become.

Further, by using the above-mentioned transmittance change detecting method to judge the completion of switching of the light beam attenuation optical element 102, a control signal is output from the microcomputer 114, and the control signal is passed through the optical element drive section 115. Despite trying to switch the light beam attenuating optics 102,
If the microcomputer 114 outputs the control signal for switching the optical beam attenuating optical element 102 again when the optical beam attenuating optical element 102 is not actually switched, a reliable switching operation of the optical beam attenuating optical element 102 becomes possible.

Next, the structure of the light beam attenuation optical element 102 will be described in detail with reference to FIG. FIG. 6 is a schematic diagram showing the configuration of the light beam attenuating optical element 102 and the change in transmittance due to its operation. (A) is a schematic diagram of a configuration in which a light beam attenuating optical element 102 having a constant transmittance is put in and out of an optical path.

In this case, for example, the light beam attenuation optical element 1
If the transmittance of 02 is 50%, the switching of the transmittance is
By switching the light beam attenuation optical element 102 in and out, two states can be switched. That is, when the light beam attenuating optical element 102 is taken out of the optical path, the transmittance is 10
There are two states of 0% and a transmittance of 50% when the light beam attenuation optical element 102 is inserted in the optical path. In the case of this configuration, during the operation of moving the optical beam attenuating optical element 102 in and out of the optical path, a part of the light beam is reduced by the optical beam attenuating optical element 102 to a light amount of 50%, and the other portion is attenuated. There is a state in which the light amount is 100%.

If there is an imbalance in the amount of light in a certain direction on the cross section of the light beam, the objective lens 10
The beam spot of the light beam convergently irradiated from 7 on the optical disc 108 becomes an optically deteriorated beam pot having a spread in the above-mentioned unbalance direction.
The FE signal and the TE signal based on the reflected light of the light beam having such a beam pot are changed from the normal signal due to the influence of the deteriorated beam spot. For example, the TE signal by the push-pull method has a small signal amplitude, and in the worst case, the signal amplitude may be zero. Therefore, the optical beam attenuation optical element 10 as described above is used.
It is considered that the imbalance of the transmittance due to 2 affects the focus control and the tracking operation.

However, in the case of the configuration of (a), by utilizing the judgment of the completion of switching of the light beam attenuation optical element 102 using the above-mentioned transmittance change detection method, the influence on the control signal due to the switching is exerted. It can be avoided. That is, in the case of the configuration of (a), in order to avoid the influence of the above-mentioned disturbance on the control, the light beam attenuation optical element 10
The focus control operation by the focus control means and the tracking control operation by the tracking control means are interrupted at the start of the switching of No. 2, and the control operation is restarted again after the completion of the switching of the light beam attenuation optical element 102 is detected. In this way, the influence on the control signal due to the switching of the light beam attenuation optical element 102 can be avoided. Further, in general, focus control is more stable than tracking control. Therefore, it is also possible to interrupt only tracking control and restart the control operation after detecting completion of switching of the light beam attenuation optical element 102.

On the other hand, (b) is a schematic diagram of a configuration in which the position of the light beam attenuation optical element 102 having a plurality of transmittances is changed with respect to the light beam passing therethrough. For example, as shown in (b), consider a configuration in which the transmittance becomes ternary such as 100%, 75%, and 50% depending on the position. In this case, by moving the light beam attenuation optical element 102, the transmittance of 1
When switching between 00% and 50%, a state in which the transmittance is 75% is generated during the switching, so that the change in the transmittance during the switching operation of the light beam attenuation optical element 102 becomes gradual. The degree of imbalance of the transmittance due to the optical beam attenuating optical element 102 is smaller than that of.

Therefore, the FE caused by this imbalance
The change in the signal and the TE signal is smaller than that in (a).
Therefore, in the case of the configuration of (b), the light beam attenuation optical element 10
Since the influence on the control signal due to the switching of No. 2 is considered to be small, the switching operation of the light beam attenuating optical element 102 can be performed without interrupting the focus control operation and the tracking control operation. As a result, the switching of the light beam attenuating optical element 102 can be performed without interrupting the focus control operation and the tracking control operation, so that the switching between the reproducing operation and the recording operation of the single-layer disc can be continuously performed.

In the present embodiment, the light beam attenuation optical element 102 is assumed to have a ternary transmittance depending on its position, but the value is not limited to this value, and a plurality of stepwise gradations may be selected depending on the position. It suffices if it is configured to have a high transmittance.

Next, the change in the output power of the light source 101 due to the switching of the light beam attenuation optical element 102 and the switching of the additional voltage amount to the FE signal and the TE signal according to the change will be described. FIG. 7 is a schematic diagram showing a zero point shift (hereinafter referred to as stray light offset) of an error signal due to stray light inside the optical head when the light source 101 emits laser light and a method of canceling it.

As shown in FIG. 7, when the error signal output before and after the laser emission of the light source 101 is compared, a change is seen in the DC component. This change amount Vofs is called a stray light offset amount, which is a result of the light beam emitted from the light source 101 being reflected inside the optical head and entering the second detector 112, and is caused by the reflected light from the optical disc 108. Not a thing. If control is performed on the basis of such an error signal having stray light offset, the optimum control state cannot be realized and reproduction jitter deteriorates.

Therefore, it is necessary to eliminate the stray light offset in the error signal, and the stray light offset can be eliminated by the method described below. That is, the stray light offset amount V
By eliminating the stray light offset, a voltage -Vofs (hereinafter referred to as a stray light offset cancel voltage) that detects the ofs at startup and cancels the detected stray light offset amount is added to the error signal in the error signal generation unit. Is possible.

However, most of the stray light offset amount Vofs changes according to the light emission power value of the light source 101. Therefore, in order to eliminate the stray light offset, the stray light offset cancel voltage −Vof according to the change of the light emission power value.
It is necessary to switch s appropriately. That is, it is necessary to switch the stray light offset cancel voltage -Vofs when switching between the recording operation and the reproducing operation and when switching between the single-layer disc and the dual-layer disc.
The stray light offset amount Vofs in each operating state is detected and stored when the optical disk device is started.

The method of detecting the stray light offset amount Vofs in each operating state at the time of starting the optical disk device will be described in detail later. Further, the switching of the recording / reproducing operation and the switching between the single-layer disc and the double-layer disc targeted in the above are accompanied by the switching of the light beam attenuation optical element 102. Therefore, the stray light offset cancellation voltage −Vofs is switched to an appropriate stored voltage in accordance with the state before and after the switching of the light beam attenuation optical element 102, whereby the stray light offset of the error signal can be eliminated.

Here, a method of detecting the stray light offset amount in each operation state at the time of starting the optical disk device will be described. First, at the time of start-up, an optical head moving means (not shown in FIG. 1) for moving the optical head in the radial direction of the optical disc 108 moves the optical head to the outer periphery of the optical disc 108, and there is no reflected light from the optical disc. Put in a state. In this state, the light beam power control means sets the irradiation power to, for example, the reproduction power for the single-layer disc. By measuring the stray light offset amount at this time, the stray light offset amount during the reproducing operation of the single-layer disc can be obtained. Similarly, the stray light offset amount in each operation state can be determined by measuring the stray light offset amount in the recording operation of the single-layer disc, the reproducing operation of the double-layer disc, and the recording operation of the double-layer disc. The series of stray light offset amount detections at the time of startup described above is called stray light offset learning.

By using such a stray light offset learning result, it is possible to obtain the FE signal and the TE signal without the influence of the change in the light emission power of the light source 101 before and after the switching of the light beam attenuation optical element 102. Optimal focus control and tracking control according to the states before and after the switching of the beam attenuation optical element 102 are possible.

Further, during the switching operation of the light beam attenuation optical element 102, the light amount control signal output outputted from the microcomputer 114 to the light source drive 115 is monitored, and the stray light offset cancel voltage is adjusted to the light beam in accordance with the continuous change. By continuously changing the value before switching the attenuation optical element 102 to the value after switching, the stray light offset of the error signal can be appropriately eliminated even during the switching operation of the optical beam attenuation optical element 102. The stray light offset cancel voltage value before and after the switching of the light beam attenuation optical element 102 used here is assumed to be previously detected by the stray light offset learning described above.

Therefore, even during the switching operation of the optical beam attenuating optical element 102, it is possible to obtain the FE signal and the TE signal without the influence of the change in the light emission power of the light source 101, so that the optical beam attenuating optical element 102 is switched. Optimal focus control and tracking control are possible during operation.

In the present embodiment, the transmitted light quantity changing means has a structure for changing the transmittance by mechanically moving the light beam attenuation optical element 102 into and out of the optical path according to a signal from the optical element driving section 115. However, even in the configuration in which the liquid crystal filter is used instead of the light beam attenuation optical element 102 and the transmittance of the light beam passing through the liquid crystal filter is changed to a predetermined transmittance by the signal from the optical element driving unit 115, You can get the effect.

As described above, in the first embodiment, the light beam attenuating optical element 1 depends on the type of the disc.
By switching 02, it is possible to make the output power of the light source high so that the quantization noise is sufficiently low, while the irradiation power can be reproduced at a low power without deterioration of the recording layer or erasing of data, so that low noise can be achieved. A good playback state can be achieved with.

Further, since it is possible to detect the change in the transmittance of the light beam attenuation optical element 102, which is the means for changing the amount of transmitted light, by monitoring the output of the light amount control signal or the reproduction jitter, a dedicated sensor or the like is added for detection. No elements needed.

Further, since the switching operation of the light beam attenuation optical element 102 can be performed without interrupting the focus control operation and the tracking control operation at the time of start-up, continuous operation can be performed at the time of switching between the reproducing operation and the recording operation.

Further, since the zero point shift of the FE signal and the TE signal can be appropriately eliminated in accordance with the switching operation of the optical beam attenuation optical element 102, the optimum focus control and tracking in the switching operation of the optical beam attenuation optical element 102 are performed. It becomes possible to control.

(Second Embodiment) FIG. 8 is a block diagram showing the structure of an optical disk device according to the second embodiment. The same parts as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted. The operation of the optical disc device according to the second embodiment will be described with reference to FIG.

The linearly polarized light emitted from the light source 101 enters the light beam attenuation optical element 102. The light beam that has passed through the light beam attenuation optical element 102 is incident on the polarization beam splitter 103. The light beam that has passed through the polarization beam splitter 103 is incident on the collimator lens 104 and is collimated by the collimator lens 104. The light beam transmitted through the collimator lens 104 is
Circularly polarized light by the quarter-wave plate 105, and the half mirror 10
A light beam having a light amount of about 90% is reflected at 6, and a light beam having a light amount of about 10% is transmitted through the half mirror 106. The light beam reflected by the half mirror 106 is the objective lens 1
The light beam is incident on the optical disc 07 and is converged onto the optical disc 108.

The light beam transmitted through the half mirror 106 is incident on the first condenser lens 109 and then on the first detector 110. The light beam incident on the first detector 110 is converted into an electric signal, becomes an electric signal for monitoring the light amount of the light beam emitted from the light source 101, and is input to the microcomputer 114, and the light source 101 outputs a predetermined light amount. Thus, the light amount control signal is output. The light amount control signal output from the microcomputer 114 is used as the light source driving unit 11
5, and the light source 101 is controlled to output a predetermined amount of light.

Next, the light beam reflected from the optical disk 108 passes through the objective lens 107 and the half mirror 1
06, transmitted through the quarter-wave plate 105, and the light source 1
The linearly polarized light orthogonal to the light beam emitted from 01 is transmitted through the collimator lens 104 and reflected by the polarization beam splitter 103. The light beam reflected by the polarization beam splitter 103 is reflected by the second condenser lens 11
The light is condensed by 1 and is incident on the second detector 112. The light beam incident on the second detector 112 is converted into an electric signal and output to the FE signal generation unit 117, the TE signal generation unit 121, and the reproduction jitter detection unit 125.

The FE signal generation unit 117, based on the signal from the second detector 112, the focus error signal (FE signal) indicating the converged state of the light beam converged and irradiated on the optical disc 108 by the astigmatism method, for example. Is generated and output to the focus control unit 120. The FE signal input to the focus control unit 120 passes through a phase compensating circuit and a low frequency compensating circuit configured by, for example, a DSP digital filter, and is output to the focus driving unit 119 as a focus driving signal. Focus drive unit 11
The focus drive signal input to 9 is amplified and drives the focus actuator 118, so that the converged state of the light beam converged and irradiated on the optical disc 108 is always in a predetermined converged state.
Position is controlled along the optical axis of the lens.

The TE signal generator 121 also generates a tracking error signal (TE signal) indicating the irradiation position of the light beam by, for example, the push-pull method based on the signal from the second detector 112, and the tracking controller 12
Output to 4. The TE signal input to the tracking control unit 124 passes through a phase compensating circuit and a low frequency compensating circuit configured by, for example, a DSP digital filter, and is output to the tracking driving unit 123 as a tracking driving signal. The focus drive signal input to the tracking drive unit 123 is amplified and drives the tracking actuator 122, thereby controlling the position of the objective lens 107 so that the desired beam on the optical disc 108 is irradiated with the light beam. Further, the reproduction jitter detecting section 125 detects the jitter of the reproduction signal based on the signal from the second detector 112 and outputs it to the microcomputer 114.

Next, the reproduction signal jitter value detected by the reproduction jitter detecting section 125 and the use of the light beam attenuation optical element 102 in the second embodiment will be described in detail. Jitter of a reproduction signal is generated from various factors in an optical disk device, and one of the factors is the quantization noise of the semiconductor laser which is the light source 101. As described in the prior art, this quantization noise has a characteristic that it decreases when the output power of the semiconductor laser is increased. Here, the light beam attenuation optical element 102 is the same as that described in the first embodiment.
By using the configuration of (b), it is possible to change the transmittance stepwise according to the light beam transmission position. Alternatively, the light beam attenuating optical element 102 uses a liquid crystal filter to change the transmittance of the light beam transmitted through the liquid crystal filter to a predetermined transmittance by a signal from the optical element driving unit 115. The transmittance can be continuously changed.

Therefore, when it is determined that the reproduction signal jitter value input to the microcomputer 114 is higher than a predetermined value, the microcomputer 114 outputs an optical element drive signal to the optical element drive section 116, and the optical beam attenuation optical element is output. The output power of the light source 101 is increased by the light beam power control of the light beam power control means by lowering the transmittance than the state in which the reproduction signal jitter value is judged to be high by driving the light source 102, and thus the quantization of the light source 101 is performed. The noise goes down. By reducing the transmittance by the light beam attenuation optical element 102 as described above until the reproduction jitter value input to the microcomputer 114 becomes lower than a predetermined value, the irradiation power is not deteriorated in the recording layer or the data is erased. It is possible to reduce the quantization noise of the semiconductor laser while maintaining a predetermined power that does not occur. By the above method, the reproduction signal jitter value is reduced to a predetermined value, whereby a good reproduction state can be realized.

Next, the change range of the transmittance by the light beam attenuation optical element 102 will be described. A laser is output from the light source 101 by supplying a drive current equal to or higher than a threshold value at which laser oscillation is started to the semiconductor element. Since the output power of this laser has a characteristic proportional to the drive current of the semiconductor element, the output power can be increased by increasing the drive current value. However, if the drive current of the semiconductor element exceeds a certain value, the element is destroyed, so the output power must be lower than the value at which the element is destroyed.

Therefore, it is assumed that there is a lower limit to the range of change in the transmittance by the light beam attenuation optical element 102 in the second embodiment. By setting the lower limit of the transmittance, the output power of the light source 101 controlled by the light beam control means does not exceed a certain output power. Here, the minimum value of the transmittance by the light beam attenuating optical element 102 is set so that the irradiation power on the optical disk 108 becomes the required predetermined irradiation power when the output power of the light source 101 is the upper limit. This is the value that was set.

As described above, the optical beam attenuation optical element 10
By setting the minimum value for the transmittance by 2
Since it is possible to suppress the output power of
It is possible to prevent the semiconductor laser element of the light source 101 from being destroyed due to excessive driving current. Furthermore, in the second embodiment, when the reproduction signal jitter value does not decrease to the desired value even though the transmittance by the light beam attenuation optical element 102 is decreased to the minimum value described above, the optical disk 10
It can be determined that the disc 8 is an inappropriate disc that cannot be reproduced by this optical disc device.

As described above, in the second embodiment, when the reproduction signal jitter value is higher than the predetermined value,
Since the reproduction signal jitter value can be reduced by reducing the transmittance of the light beam attenuation optical element 102, a good reproduction state can be realized. Further, by setting the minimum value for the transmittance of the light beam attenuation optical element 102, it is possible to prevent the semiconductor laser element of the light source 101 from being destroyed due to excessive current.

[0083]

The optical disk device of the present invention comprises a light source for generating a light beam, and an irradiation power detecting means for detecting the power of the light beam applied to the optical disk by the light source.
A light beam power control means for driving the light source so that the output of the irradiation power detection means has a predetermined value, and a power increase / decrease capable of attenuating or amplifying the power of the light beam while reaching the optical disc from the light source. Means and
With the increase / decrease detecting means for detecting that the power of the light beam is increased / decreased by the power increasing / decreasing means, the output power of the light source is increased according to the type of the disk while the quantization noise is sufficiently low, and the irradiation is performed. Since the power can be reproduced at low power without deterioration of the recording layer or erasing of data, a good reproduction state with low noise can be realized.

In the optical disk device of the present invention, the power increasing / decreasing means comprises a transmitted light quantity changing means capable of varying the transmittance, and a transmitted light quantity controlling means changing the transmittance of the transmitted light quantity changing means, and the increase / decrease detecting means comprises: Since the transmittance change detecting means for detecting the change in the transmittance of the transmitted light quantity changing means is provided, by changing the transmittance by the optical element according to the type of the disc, the quantization noise of the output power of the light source is reduced. It is possible to realize a good reproduction state with low noise because it is possible to perform reproduction with a low power that does not cause deterioration of the recording layer and data erasing while making the high power sufficiently low.

In the optical disk device of the present invention, the transmittance change detecting means is configured to detect the transmittance change by comparing the detection result by the irradiation power detecting means with the drive value of the light source by the light beam power control means. Therefore, the change in transmittance can be detected without adding a dedicated detection element such as a sensor.

The optical disk apparatus of the present invention comprises a reproduction jitter detecting means for detecting the jitter of the reproduction signal of the data recorded on the optical disk, and the transmittance change detecting means is the reproduction jitter value detected by the reproduction jitter detecting means. Since the change in transmittance is detected by the change, the change in transmittance can be detected without adding a dedicated detection element such as a sensor.

In the optical disk device of the present invention, when the transmitted light quantity control means changes the transmittance of the transmitted light quantity changing means, and when the transmittance change detecting means determines that the transmittance does not change, the transmitted light quantity control means. With this configuration, the transmittance is changed again, so that a reliable change in transmittance can be realized.

The optical disc apparatus of the present invention comprises focus error detecting means for detecting a deviation between the focus and the information surface of the light beam convergently irradiated on the information surface of the optical disc, and the light beam convergently irradiated on the information surface of the optical disc and the information. And a tracking error detecting means for detecting the deviation of the track on the surface,
Since the offset of the output signal of the focus error detecting means and / or the tracking error detecting means is changed when the transmittance of the transmitted light amount changing means is changed, the FE signal and the FE signal before and after the change of the transmittance are changed. Since the zero shift of the TE signal can be eliminated properly,
Optimal focus control and tracking control are possible.

Since the optical disk device of the present invention is constructed so that the offset of the output signal of the focus error detecting means and / or the tracking error detecting means is continuously changed according to the change of the drive value of the light source. ,
Since the zero point shift of the FE signal and the TE signal can be appropriately eliminated while the transmittance is changing, optimal focus control and tracking control can be performed.

The optical disc apparatus of the present invention has focus control means for controlling the focus of the converged and irradiated light beam to be located on the information surface of the optical disc, and the converged and irradiated light beam on the track of the optical disc. Tracking control means for controlling the transmission light quantity changing means to change the transmittance of the transmitted light quantity changing means in a state in which the focus control means or the focus control means and the tracking control means are operated. With this configuration, continuous operation is possible at the time of switching between the reproducing operation and the recording operation accompanied by the change in transmittance.

In the optical disk device of the present invention, the transmitted light amount control means changes the transmittance stepwise or continuously, so that when the reproduction operation and the recording operation are switched with the change of the transmittance. , Continuous operation is possible.

In the optical disk device of the present invention, a light source for generating a light beam, an irradiation power detecting means for detecting the power of the light beam applied to the optical disk by the light source, and an output of the irradiation power detecting means have a predetermined value. Light beam power control means for driving the light source so that the power of the light beam can be attenuated or amplified while reaching the optical disc from the light source, and the light beam power control means The output of the reproduction jitter detection means includes an increase / decrease detection means for detecting an increase / decrease in power, and a reproduction jitter detection means for detecting a jitter of a reproduction signal of information recorded on the disk based on reflected light from the optical disk. Since the power increase / decrease means is controlled based on the above, when the reproduction signal jitter value is higher than a predetermined value, the output power of the light source is Over the order to be able to reduce the reproduction signal jitter value by a high-power quantization noise is sufficiently low, satisfactory reproduction state can be realized.

In the optical disk device of the present invention, the power increasing / decreasing means comprises a transmitted light quantity changing means capable of varying the transmittance and a transmitted light quantity controlling means for changing the transmittance of the transmitted light quantity changing means, and the increase / decrease detecting means comprises: The change in the transmittance of the transmitted light amount changing means is configured to be detected by comparing the detection result by the irradiation power detecting means and the drive value of the light source by the light beam power control means, and the transmitted light amount changing means is Since the transmittance is changed based on the output of the reproduction jitter detecting means, when the reproduction signal jitter value is higher than a predetermined value, the transmittance is changed by using an optical element and the output power of the light source is changed to quantization noise. Since it is possible to lower the reproduction signal jitter value by setting the high power so that
A good reproduction state can be realized.

In the optical disk device of the present invention, the transmitted light amount control means is configured to lower the transmitted light amount of the transmitted light amount changing means until the output value of the reproduction jitter detection means falls below a predetermined value. Also, when the reproduction signal jitter value is higher than a predetermined value, the reproduction signal jitter value can be reduced by further reducing the transmittance, and thus a good reproduction state can be realized.

In the optical disk device of the present invention, the minimum value of the transmittance of the transmitted light amount changing means is set so that the level of the driving value of the light source is equal to or less than the rated value of the light source, so that the reproduction jitter value is lowered. It is possible to prevent the semiconductor laser device of the light source from being broken due to excess current when the transmittance is continuously reduced.

In the optical disk device of the present invention, when the transmittance of the transmitted light amount changing means reaches the set minimum value and the output value of the reproducing jitter detecting means is not below the predetermined value, the reproducing operation is performed. Since it is configured to stop, it can be determined that the optical disc to be played back is an inappropriate disc that cannot be played back by this optical disc device.

[Brief description of drawings]

FIG. 1 is a block diagram of an optical disc device according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram showing a difference in structure between a single-layer disc and a double-layer disc for explaining the first embodiment.

FIG. 3 is a characteristic diagram showing that the switching timing of the light beam attenuation optical element can be detected by a change in irradiation power and light amount control signal output in the first embodiment.

FIG. 4 is a waveform diagram showing the occurrence of reproduction jitter due to noise that has entered the reproduction signal for explaining the first embodiment.

FIG. 5 is a characteristic diagram showing that the switching timing of the optical beam attenuation optical element can be detected by a change in reproduction jitter in the first embodiment.

FIG. 6 is a schematic diagram showing a configuration of a light beam attenuation optical element according to the first embodiment and a change in transmittance due to the operation thereof.

FIG. 7 is a schematic diagram showing a stray light offset of an error signal and a method of canceling the stray light offset in the first embodiment.

FIG. 8 is a block diagram of an optical disk device according to a second embodiment of the present invention.

[Explanation of symbols]

101 light source 102 light beam attenuation optical element 103 Polarizing beam splitter 104 Collimator lens 105 1/4 wave plate 106 half mirror 107 Objective lens 108 optical disk 109 first condenser lens 110 First detector 111 Second condenser lens 112 Second detector 113 Reflectance Detector 114 Microcomputer 115 Light source driver 116 Optical element driver 117 Focus error signal (FE signal) generation unit 118 focus actuator 119 Focus drive unit 120 Focus control unit 121 Tracking error signal (TE signal) generation unit 122 Tracking actuator 123 Tracking drive 124 Tracking control unit 125 Playback jitter detector

Front page continuation (51) Int.Cl. ⁷ identification code FI theme code (reference) G11B 7/125 G11B 7/125 C (72) Inventor Katsuya Watanabe 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Kenji Fujiune, 1006 Kadoma, Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Yuichi Kuze, 1006, Kadoma, Kadoma City, Osaka F-Term (Reference) 5D090 AA01 CC04 CC16 EE11 FF08 HH01 LL08 5D118 AA14 BA01 BF02 CC12 CD02 CD03 DA40 5D119 AA12 AA34 AA43 BA01 DA05 JA58 5D789 AA12 AA34 AA43 BA01 DA05 JA58

Claims (14)

[Claims] 1. A light source for generating a light beam, an irradiation power detection means for detecting the power of the light beam applied to the optical disk by the light source, and an output of the irradiation power detection means so as to have a predetermined value. A light beam power control means for driving the light source, a power increasing / decreasing means capable of attenuating or amplifying the power of the light beam while reaching the optical disc from the light source, and a light beam power increasing / decreasing by the power increasing / decreasing means And an increase / decrease detecting unit for detecting 2. The power increasing / decreasing means comprises a transmitted light quantity changing means capable of varying the transmittance, and a transmitted light quantity controlling means changing the transmittance of the transmitted light quantity changing means, and the increase / decrease detecting means comprises:
The optical disk device according to claim 1, further comprising a transmittance change detection unit that detects that the transmittance of the transmitted light amount changing unit has changed. 3. The transmittance change detecting means is configured to detect the transmittance change by comparing the detection result by the irradiation power detecting means with the drive value of the light source by the light beam power control means. The optical disk device according to claim 2. 4. A reproduction jitter detecting means for detecting a jitter of a reproduction signal of data recorded on an optical disk, wherein the transmittance change detecting means changes the transmittance according to a change of the reproducing jitter value detected by the reproducing jitter detecting means. The optical disk device according to claim 2, wherein the optical disk device is configured to detect 5. When the transmittance change detecting means determines that the transmittance does not change when the transmittance of the transmitted light quantity changing means is changed by the transmitted light quantity controlling means, the transmittance is again adjusted by the transmitted light quantity controlling means. The optical disk device according to claim 2, wherein the optical disk device is configured to be changed. 6. A focus error detecting means for detecting a deviation between a focus and an information surface of a light beam convergently irradiated on an information surface of an optical disk, and a deviation between a light beam convergently irradiated on an information surface of an optical disk and a track of the information surface. Tracking error detecting means for detecting, when changing the transmittance of the transmitted light amount changing means, the focus error detecting means,
Alternatively, the optical disk device according to claim 2, wherein the tracking error detection means is configured to change an offset of an output signal. 7. The focus error detecting means,
7. The optical disk device according to claim 6, wherein the offset of the output signal of the tracking error detecting means is continuously changed in accordance with the change of the drive value of the light source. 8. Focus control means for controlling the focus of the convergently irradiated light beam so as to be positioned on the information surface of the optical disk, and so as to position the convergently irradiated light beam on the track of the optical disk. And a tracking control unit for controlling, wherein the transmitted light amount control unit is configured to change the transmittance of the transmitted light amount change unit in a state in which the focus control unit or the focus control unit and the tracking control unit are operated. The optical disk device according to claim 2, wherein: 9. The optical disk device according to claim 8, wherein the transmitted light amount control means changes the transmittance stepwise or continuously. 10. A light source for generating a light beam, an irradiation power detection means for detecting the power of the light beam applied to the optical disk by the light source, and the output of the irradiation power detection means to have a predetermined value. A light beam power control means for driving the light source, a power increasing / decreasing means capable of attenuating or amplifying the power of the light beam while reaching the optical disc from the light source, and a light beam power increasing / decreasing by the power increasing / decreasing means An increase / decrease detecting means for detecting the reproduction jitter, and a reproduction jitter detecting means for detecting the jitter of the reproduction signal of the information recorded on the disk based on the reflected light from the optical disk, and based on the output of the reproduction jitter detecting means, An optical disk device characterized by controlling a power increasing / decreasing unit. 11. The power increasing / decreasing means comprises a transmitted light quantity changing means capable of varying the transmittance, and a transmitted light quantity control means for changing the transmittance of the transmitted light quantity changing means, and the increase / decrease detecting means includes a transmitted light quantity changing means. That the transmittance has changed
The detection result by the irradiation power detection means and the driving value of the light source by the light beam power control means are compared and detected, and the transmitted light amount changing means is based on the output of the reproduction jitter detection means. 11. The optical disk device according to claim 10, wherein: 12. The optical disc according to claim 11, wherein the transmitted light amount control means is configured to reduce the transmittance of the transmitted light amount changing means until the output value of the reproduction jitter detection means falls below a predetermined value. apparatus. 13. The optical disk device according to claim 12, wherein the minimum value of the transmittance of the transmitted light amount changing means is set such that the level of the driving value of the light source is equal to or less than the rated value of the light source. . 14. The reproducing operation is stopped when the output value of the reproduction jitter detecting means is not below a predetermined value when the transmittance of the transmitted light quantity changing means reaches a set minimum value. 14. The optical disk device according to claim 13, wherein: