JP3092758B2 - Optical disk recording / reproducing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[Table of Contents] The present invention will be described in the following order. Industrial Application Conventional Technology (FIGS. 3 to 5) Problems to be Solved by the Invention (FIGS. 3 to 5) Means for Solving the Problems (FIG. 1) Function (FIG. 1) Example (1) Configuration of Embodiment (FIGS. 1 and 2) (2) Effects of Embodiment (3) Other Embodiments Effects of the Invention

[0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk recording / reproducing apparatus, for example, an optical disk recording / reproducing apparatus for recording / reproducing desired information using a magneto-optical disc or a composite optical disc and reproducing a compact disc. May be applied.

[0003]

2. Description of the Related Art Heretofore, there has been an optical disk apparatus of this type which can record and reproduce desired information using a magneto-optical disk and reproduce a compact disk as required.

That is, in this type of optical disk device, desired information can be recorded and reproduced by irradiating the optical disk with a light beam of a laser diode. At this time, the light amount of this light beam is finely controlled. Thus, the irradiation position of the light beam is maintained at a predetermined temperature. That is, as shown in FIG. 3, the threshold current of the laser diode greatly changes in accordance with the ambient temperature, so that in this type of optical disk device, the light amount of the light beam is monitored and maintained at a constant value. I do.

That is, in FIG. 4, reference numeral 1 denotes an optical disk device as a whole, and the system control circuit 2 switches the overall operation mode and switches the light amount of the light beam L1. Therefore, the system control circuit 2 outputs the light quantity control data to the digital / analog conversion circuit (D / A) 4 and generates a control voltage V1 corresponding to the light quantity control data.

Further, in the optical disk device 1, the optical disk L is irradiated with the light beam L1 of the laser diode 6 via a predetermined optical system, and a part thereof is separated and received by the photodiode 8. The photodiode 8 has an anode connected to the power supply B, a cathode grounded through a semi-fixed resistor 10, and a thermistor 12 connected in parallel with the semi-fixed resistor 10.

As a result, in the optical disk device 1,
The light amount of the light beam L1 is monitored by the photodiode 8,
The output current of the photodiode 8 as a monitoring result is converted into a current-voltage by the semi-fixed resistor 10 and the thermistor 12.

Further, at this time, in the optical disk device 1, by connecting a thermistor 12 to the semi-fixed resistor 10 in parallel, the current-voltage conversion characteristic is corrected in accordance with the internal temperature of the optical disk device 1, whereby The temperature at the light beam irradiation position is maintained at a predetermined value even when the temperature changes.

That is, the optical disk device 1 obtains a detection voltage V2 based on the result of light quantity detection.
To the non-inverting input terminal of the operational amplifier circuit 14. Here, the operational amplifier circuit 14 is a differential amplifier circuit in which a feedback circuit is formed by a parallel circuit of a feedback capacitor 16 and a feedback resistor 18, and a control voltage V via an input resistor 20.
1 is input to the inverting input terminal.

Thus, in the optical disk device 1,
An error voltage of the light amount detection result with respect to the control voltage V1 is detected, and the error voltage is amplified and output to the transistor 22. The transistor 22 is connected to the power supply B via the emitter resistor 24, and drives the laser diode 6 with a collector output.

As a result, as shown in FIG. 5, in the optical disk device 1, the light amount of the light beam L1 is maintained at the light amount determined by the control voltage V1, and the current-voltage conversion characteristic is corrected by the thermistor 12 at this time. Thus, even when the ambient temperature changes, the temperature of the irradiation position of the light beam L1 is maintained at a constant value.

At this time, the optical disk device 1 switches and outputs control data for each optical disk, thereby maintaining the light amount of the light beam L1 at the recommended light amount recorded on the magneto-optical disk. That is, in the magneto-optical disk, various data required for recording and reproduction are recorded in advance in the innermost lead-in area in the form of TOC data. The area is reproduced and the reproduction signal processing circuit 24 executes the TOC.
Play the data.

Thus, the system control circuit 2 fetches the TOC data and outputs control data in accordance with the recommended light amount of the TOC data for each recording / reproducing mode, thereby controlling the light amount of the light beam L1. A predetermined recommended light amount is maintained for each magnetic disk.

[0014]

However, in practice, this type of magneto-optical disc requires 3 to 6 mW during recording.
Of light is required, while 0.1 to 0.3 [m
[W]. In the optical disk device, it is necessary to switch the light amount at the time of recording / reproducing correspondingly, and it is necessary to finely adjust the light amount for each optical disk and set the light amount to the recommended light amount.

However, in the conventional optical disk device, the control voltage V1
, It is necessary to finely adjust the small control voltage V1 during reproduction. For this reason, in the conventional optical disk device, at the time of reproduction, if noise is mixed in the control voltage V1, and furthermore, the ground potential may fluctuate due to the common impedance with other circuit blocks or the like. There is a problem that the light amount of L1 cannot be correctly maintained at the recommended light amount.

Further, at the time of reproduction, the resolution of the control voltage may be insufficient, and there is a problem that the CN ratio is deteriorated as a whole in the light amount control circuit.

Particularly, in the case of a compact disk, since the reflectivity is higher than that of a magneto-optical disk, it is necessary to further reduce the amount of light when reproducing a compact disk as compared to when recording and reproducing only a magneto-optical disk. is there. Therefore, when a compact disk is reproduced together, a composite optical disk having a magneto-optical recording area similar to the magneto-optical disk and a pit area similar to the compact disk formed on the outer and inner peripheral sides, respectively, is recorded. In the case of reproduction, in the optical disc device, the light beam L1
There is a problem that the light quantity of the light cannot be controlled with high accuracy.

The present invention has been made in view of the above points, and it is an object of the present invention to propose an optical disk recording / reproducing apparatus capable of controlling the amount of a light beam with high accuracy.

[0019]

In order to solve this problem, the present invention irradiates a light beam L1 onto an optical disk to record desired information on the optical disk or reproduce desired information from the optical disk. Optical disk recording / reproducing device 30
A light source 6 for generating a light beam L1, light receiving means 8 for receiving light reflected from the optical disk of the light beam L1 emitted from the light source 6 and outputting a light amount detection current, and setting the light amount of the light beam L1 Control voltage generating means 4, 36 for generating a control voltage V3 to be applied, current-voltage converting means 10, 12, 34 for converting a light quantity detection current output from the light receiving means 8 to a light quantity detection voltage V4, , 36 comparing the control voltage V3 generated by the current-voltage converters 10, 12, 34 with the light amount detection voltage V4 converted by the current-voltage converters 10, 12, 34.
4, 16, 18, 20 and comparison means 14, 16, 18,
The light source 6 is driven based on the comparison result of FIG.
Control means 22 and 24 for controlling the amount of light, and switching means 32 for switching the current-voltage conversion characteristics of the current-voltage conversion means 10, 12 and 34 during reproduction and recording.

Further, in the present invention, the current-voltage conversion means 10, 12, 34 are constituted by a thermistor for performing a correction according to the internal temperature. Further, in the present invention, the switching means 32 switches the current-voltage conversion characteristics of the current-voltage conversion means 10, 12, 34 for each optical disk.

[0021]

By switching the current-voltage conversion characteristic for converting the light quantity detection current to the light quantity detection voltage V4 during information recording and information reproduction, the light quantity can be finely controlled with a large control voltage V3 during information reproduction.

As a result, regarding the light amount of the light beam L1,
By detecting the optimum value for each optical disk and switching the control voltage V3 according to the optimum value, the amount of light can be finely controlled.

[0023]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.

(1) Configuration of the embodiment In FIG. 1 in which the same reference numerals are assigned to parts corresponding to those in FIG. 3, reference numeral 30 denotes an optical disk device as a whole, which includes a magneto-optical disk, a composite optical disk and a compact disk. Is used to record and reproduce desired information.

That is, in the optical disk device 30,
When the optical disk is loaded, the lead-in area of the optical disk is reproduced with a predetermined reproduction light amount, and thereby the TOC data recorded in this lead-in area is reproduced. After reading the TOC data from the reproduction signal processing circuit 24, the system control circuit 36 outputs control data to each circuit block when the user presses a recording or reproduction operation element to change the entire operation mode to the recording mode. Or, switch to the playback mode.

At the same time, the system control circuit 36 outputs control data to the digital / analog conversion circuit 4 so that the digital / analog conversion circuit 4 controls the control voltage V
3 is generated, and the light amount of the light beam L1 is set to a recommended value.
Further, the system control circuit 36 outputs control data to the selection circuit 32, thereby connecting the semi-fixed resistor 34 to the photodiode 8 when the reproduction mode is selected, and when the recording mode is selected, Semi-fixed resistor 10
And the thermistor 12 is connected to the photodiode 8.

Thus, in the optical disk device 30, when the output current of the photodiode 8 is converted into the detection voltage V4, the current-voltage conversion characteristics are switched between the recording mode and the reproduction mode. Thus, as shown in FIG.
In the optical disk device 30, the setting range of the control voltage V3 can be maintained in the same range in the recording mode and the reproducing mode by switching the current-voltage conversion characteristics in the recording mode and the reproducing mode.

Thus, in the optical disk device 30, during reproduction, the change in the amount of light can be kept small with respect to the change in the control voltage V3, so that the resolution can be set finely. Therefore, even when noise is mixed into the control voltage V3, and even when the ground potential fluctuates due to the common impedance between the control voltage V3 and other circuit blocks, the light amount of the light beam L1 can be correctly maintained at the recommended light amount. A sufficient CN ratio can be ensured also for the entire control circuit.

Thus, even when reproducing a compact disk having the smallest light quantity, the optical disk device 3
In the case of 0, the light amount of the light beam L1 can be reliably controlled with high accuracy, and the recorded information can be surely reproduced and the reliability can be improved accordingly.

(2) Effects of the Embodiment According to the above configuration, when the output current of the photodiode 8 is converted into the detection voltage V4, the current-voltage conversion characteristics are switched between the recording mode and the reproduction mode, whereby the recording is performed. The setting range of the control voltage V3 can be kept in the same range in the mode and the reproduction mode, and thus the light beam L1
Can be reliably controlled with high accuracy, the recorded information can be reliably reproduced, and the reliability can be further improved.

(3) Other Embodiments In the above-described embodiment, the case where the current-voltage conversion characteristics are switched between the recording mode and the reproduction mode has been described. However, the present invention is not limited to this. Alternatively, the current-voltage conversion characteristics may be switched according to the type of optical disk.

Further, in the above-described embodiment, the case where the temperature characteristics of the laser diode are ensured by using the thermistor has been described. However, the present invention is not limited to this. May be compensated to compensate for the temperature characteristics.

Further, in the above-described embodiment, the case where the control data output from the system control circuit is converted into the control voltage by the digital-to-analog conversion circuit has been described. However, the present invention is not limited to this. Rectified to generate a control voltage.

Further, in the above-described embodiment, the case where desired information is recorded / reproduced using a magneto-optical disk, a compact disk, and a composite type optical disk has been described. However, the present invention is not limited to this. The present invention can be widely applied to a case where desired information is recorded / reproduced using a disk, and a case where desired information is recorded / reproduced using a write-once compact disc or a composite optical disc.

[0035]

As described above, according to the present invention, when the light amount detection current is converted into the light amount detection voltage, the current-voltage conversion characteristic is switched between recording and reproduction, so that recording and reproduction can be performed. The setting range of the control voltage can be kept in the same range, whereby it is possible to obtain an optical disk device capable of reliably controlling the light amount of the light beam with high accuracy.

[Brief description of the drawings]

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

FIG. 2 is a characteristic curve diagram for explaining the operation.

FIG. 3 is a characteristic curve diagram showing a temperature characteristic of a laser diode.

FIG. 4 is a block diagram showing a conventional optical disk device.

FIG. 5 is a characteristic curve diagram for explaining the operation.

[Explanation of symbols]

1, 30 optical disk device, 2, 36 system control circuit, 6 laser diode, 8 photodiode, 10, 34 semi-fixed resistor, 32 selection circuit.

Claims (3)

(57) [Claims] An optical disk is irradiated with a light beam, and said light beam is irradiated on said optical disk.
Record the desired information on the disc or from the optical disc
An optical disk recording / reproducing apparatus for reproducing desired information
Te, a light source for generating the light beam, the optical disc of the light beam emitted from the light source
Light receiving means that receives the reflected light from
Generates a stage and a control voltage to set the light intensity of the light beam
Control voltage generating means for detecting the light amount and the light amount detection current output from the light receiving means.
Current-voltage conversion means for converting the voltage into an output voltage, and the control voltage generation means
Converted by control voltage and current-voltage conversion means
A comparing unit that compares the light amount detection voltage with the light source, and driving the light source based on a comparison result of the comparing unit.
Control means for controlling the light quantity of the light beam; and current-voltage conversion of the current-voltage conversion means during reproduction and during recording.
Switching means for switching switching characteristics.
Optical disk recording and reproducing device. 2. The current-to-voltage converter comprises a thermistor for performing a correction according to an internal temperature.
2. The optical disk recording / reproducing method according to claim 1, wherein:
apparatus. (3) The switching means, For each of the optical disks, the current
Switching pressure conversion characteristics The method according to claim 1,
Optical disk recording and reproducing device.