JPH05210865A - Optical data storing and reproducing device - Google Patents

Abstract

PURPOSE:To quicken the rise of laser power at a recording time and to stably and acculately control laser power in an optical data storing and reproducing device using a high frequency module as a light source. CONSTITUTION:An HFM superimposition storage part 119 and an HFMOFF signal 152 are provided and the HFMOFF signal 152 is turned OFF in a fixed interval at a reproducing time before recording and the difference of the voltage laser driving voltage between the HFMON and the HFMOFF is stored in the HFM superim-position storage part 119 and added at a recording time. Further, an HFM exclusive stabilized power supply 218 is provided and the oscillation amplitude of the HFM is stabilized. Thus, the stable optical data storing and reproducing device with high accuracy and with the quick rise at the starting time of recording is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention uses a large-capacity and exchangeable information medium represented by an optical disk, and a laser element or a high-frequency module for recording / reproducing data on / from the information medium. The present invention relates to an optical data storage / reproduction device that drives a drive (hereinafter referred to as HFM).

[0002]

2. Description of the Related Art In recent years, development and commercialization of optical data storage / reproduction devices have been actively carried out. Further, in order to stably and accurately record information on an information medium, there is a demand for a technique for controlling radiation of optical power with extremely high precision.

A conventional optical data storage / reproduction device will be described below with reference to the drawings. FIG. 8 shows the main part of the optical data storage / reproduction device. In FIG. 8, 5
01 is an information medium, 502 is an optical head, 503 is a laser,
504 is an HFM, 505 is a light receiving element, and 506 is a laser H.
FM drive circuit, 507 data reproducing means, 508 CP
U. FIG. 5 shows a laser HFM drive circuit of a conventional optical data storage / reproduction device. In FIG.
301 is an HFM, 302 is a laser, 303 is a light receiving element,
Reference numeral 304 is an I / V conversion unit for performing current-voltage conversion, 305 is a reproduction reference voltage, 306 is a recording reference voltage, 307 is a voltage comparison unit, 308 is a fixed recording voltage unit, 309 is an addition unit, 3
11 is an analog switch, 317 is another circuit block,
Reference numeral 350 is a reproduction / recording switching signal, and 351 is a data signal transferred from the CPU 508. FIG. 7 shows the current-optical characteristics of the laser and HFM of the optical data storage / reproduction device.

The operation of the optical data storage / reproducing apparatus having the above structure will be described below. First, as shown in FIG. 8, in the optical data storage / reproducing apparatus, the recording data is transferred from the CPU 508 to the laser HFM drive circuit 506 during recording, and the laser 503 converts the electric signal into the optical signal. It is converted and recorded on the information medium 501.
At the time of reproduction, laser light weaker than that at the time of recording is emitted from the laser 503 to the information medium 501, and the reflected light is converted from an optical signal to an electric signal in the data reproducing means 507, and the CPU
508. Here, the reproducing means 507 is composed of an optical system such as a lens and a prism arranged on the optical head 502, a photoelectric conversion element (hereinafter referred to as a detector), and the like, and is mostly shared by the recording section and the reproducing section. Is generally used, but for convenience of explanation, it is treated as a separated and independent block. Next, the operation of the laser HFM drive circuit 506 will be described with reference to FIG.
Described in. A part of the optical power emitted by the laser 302 is received by the light receiving element 303, and current / voltage conversion is performed by the I / V conversion 304. An analog switch 311 selects a reproduction reference voltage 305 during reproduction and a recording reference voltage 306 during recording. In the voltage comparison 307, the outputs of 304 and 311 are compared, and the error signal and the recording fixed voltage 308 are added by the adder 309 and output to the base of the transistor-313. Since the recording fixed voltage 308 requires a laser driving current several times larger during recording, the reference voltage is used when the laser output is controlled only by switching the reference voltage from the reproducing 305 to the recording 306. The target value changes according to the potential difference, and the transient response time is I-
It is delayed by the response characteristics of the V conversion 304 and the voltage comparison unit 307, and a time delay of several μS occurs until the recording laser output stabilizes. Therefore, a voltage corresponding to the laser current difference at the time of recording and at the time of reproducing is prepared in advance as the fixed voltage 308, and at the time of recording, the rise of the recording laser determined by the response speed of the transistor 313 in the driving stage is realized. As a result, the rise time can be halved as compared with the method in which the fixed voltage is not added, and the time margin at the time of recording can be secured. For this reason, the fixed recording voltage 308 is not added during reproduction. Here, in the voltage comparison unit 307, since the average value of the signal at the time of recording changes depending on the recording data, switching to the peak hold type is also effective, but it will not be described in detail here.

Since the data 351 is "L" at the time of reproduction, the transistor-314 is turned off and the collector current of the transistor-313 all flows to the laser 302. When the optical output of the laser 302 is lowered due to a temperature change or the like, the error signal of the voltage comparison 307 increases the current of the laser 302 to control the optical output to be constant. Data 3 during recording
The modulated recording data "L" and "H" are input to 51, whereby the transistor-314 turns "OFF" and "ON", the laser "lights" and "non-lights", and the information The modulated data is recorded on the medium 501. In addition,
For the purpose of reducing noise by returning light from the information medium 501 to the laser 302 when the laser 302 is emitting light during reproduction,
HFM301 only during playback from playback record switching signal 350
Laser is oscillated at high frequency, and laser 3 is passed through capacitor-316.
02 is superimposed with a high frequency of several hundred MHz.

Next, the operation timing of each signal will be described with reference to the timing chart of FIG. T31 is playback mode
The recording start mode is indicated by T32, and the recording stabilization mode is indicated by T33. In the T32 mode, the recording fixed voltage 308 adjusted during the initial adjustment is added to the voltage required for the reproducing light power in the T31 mode, and the recording light power emits light. However, the voltage required for reproducing light power is mainly during HF adjustment and during HF adjustment.
The optical power in T32 mode is not stable because the oscillation amplitude of the HFM changes due to changes in the power supply voltage of M and changes in temperature. In the T33 mode, the recording reference voltage 306, the light receiving element 303, and the IV conversion 30 shown in FIG.
4. The control of the feedback loop constituted by the voltage comparison unit 307 becomes dominant and the servo characteristic stabilizes the recording light power at the recording reference voltage.

Here, the above-mentioned recording power is T32 in FIG.
The reason why the mode is not stable will be described with reference to FIG. FIG. 7 shows current-optical characteristics showing the relationship between the driving current of the semiconductor laser and the optical power. 401 is the current-optical characteristics of the laser unit at the standard temperature, and 401 'is the temperature fluctuation.
In the state where 1 is shifted, 402 is the current-optical characteristic at the time of low power near the reproduction output when HFM is added to the laser.
Reference numeral 2'indicates current-optical characteristics when the output amplitude of the HFM added by 402 changes due to power supply voltage fluctuations, temperature fluctuations, and the like. As shown in the figure, when the optical output exceeds a certain level, which exceeds the amplitude of the HFM, even when the HFM is added, the same curve 401 as that of the laser alone overlaps. This is because the average value of the AC component of which the laser output is changing due to the high frequency becomes 0, which coincides with the DC output of the laser unit. On the other hand, when the laser output is low, the superimposed high-frequency waveform is saturated at the point where the laser output becomes 0 and causes distortion, so the average value of the laser output modulated by the high frequency does not become 0. Since it has a little + DC component, the laser drive current is apparently reduced. Actually, the amount of decrease in the driving current is flowing in from the HFM.

Here, in the initial adjustment state 403 and the current-optical characteristics 402 and 401 in the same figure, in the reproducing state, a low optical output of about 1 mW of (P1, I1),
Is accurately controlled by the control loop based on the reproduction reference voltage 305. In the recording state, the output of (P3, I3) is about several mW, which is controlled by the control loop by the recording reference voltage 306 and the recording fixed voltage 308 in FIG. In the relationship between FIG. 5 and FIG. 7, the voltage comparison unit V3 of FIG.
The voltage corresponding to the point A is Vx of 403 in FIG. 7, and the voltage corresponding to the recording fixed voltage V3B is Vy of 403 in FIG. Although Vx and Vy are displayed as current values in FIG. 7, they are treated as voltages proportional to the currents.

Next, when temperature fluctuations occur and the current-optical characteristics of the laser change to curves 401 'and 402', the operating points are (P1, I2) in the reproducing state and (P3, in the recording state. I4), the current distribution indicated by 404 in FIG. 7 is obtained, and the current value corresponding to the output of the voltage comparison unit V3A is V
x ′, the current value corresponding to the recording fixed voltage portion is Vy which is the same as in the initial state, and the drive current changes but the optical output does not change from point P3. This is because the current-light characteristics of the semiconductor laser only change the light emission threshold depending on the temperature, and the slopes of 401 and 401 'hardly change in the practical range.

However, when the temperature characteristic and the voltage characteristic of the HFM change independently of the characteristic change of the semiconductor laser, the operating point when the current-light characteristic is represented by 402 'and 401 is, for example, At the time of reproduction (P1, I2), at the beginning of recording, the recording reference voltage 306 is passed through (P4, I4).
When becomes dominant, it becomes stable at (P3, I3). This is because the temperature change rate of the light receiving element 303 is generally much smaller than that of a laser or other elements, so that when the power servo during recording stabilizes, it will converge to the initial adjustment value.

[0011]

However, in the above-mentioned conventional structure, the time required for stabilizing the recording control of the laser can be extremely shortened, and it is effective for speeding up the recording and securing a time margin at the time of recording. However, as mentioned above, HF
If the correlation between the current-optical characteristics during reproduction and recording cannot be obtained, such as when the amount of high-frequency superimposition on the laser changes due to fluctuations in the M oscillation amplitude, or when the temperature characteristics of the semiconductor laser and the HFM differ greatly, FIG. T32 until the recording control shown becomes stable
In the mode, there is a problem that the laser power becomes too low or too high, and the recording margin to dust and dust decreases. If it is too high, the life of the laser may be extremely shortened if it is remarkable.

The present invention solves the above-mentioned conventional problems. Even when the semiconductor laser and the HFM have greatly different temperature characteristics, the correction value is detected or the HFM oscillation amplitude is stabilized to keep the laser power constant. It is an object of the present invention to provide an optical data storage / reproduction device for keeping the same.

[0013]

In order to achieve this object, the optical data storage / reproducing apparatus of the present invention has a function for writing data to an information medium or reading already written data. A laser light source, a high-frequency module for high-frequency superimposing on the laser light source to reduce noise when reading data, and a laser HFM drive circuit for driving the laser light source and the high-frequency module. And the high frequency module before recording
HFM superposition storage section for temporarily turning off the module and storing the current difference that is superimposed on the laser when it is on and when it is off, or means for stably operating the oscillation output of the high frequency module. ing.

[0014]

With this structure, the HFM is turned off before recording.
FF is performed, the HFM superposition amount to the laser is stored, and the superposition amount stored at the time of recording is added to the laser to correct the recording fixed voltage for speeding up the rising at the time of recording.
Further, by stabilizing the oscillation output of the HFM by using a stabilizing power supply for exclusive use of the HFM so that the temperature characteristics of the semiconductor laser and the HFM do not differ greatly, the laser recording power is stabilized and dust and dust are prevented. The recording margin can be enlarged to prevent laser damage due to large current.

[0015]

【Example】

(Embodiment 1) Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.

In FIG. 1, 101 is an HFM, 102 is a laser, 103 is a light receiving element, 104 is an I / V converter, and 1
Reference numeral 05 is a reproducing reference voltage, 106 is a recording reference voltage, 10
Reference numeral 7 is a voltage comparison unit, 108 is a fixed recording voltage unit, 109 is an addition unit, 111 is an analog switch, 117 is another circuit block, and 150 is a recording / reproduction switching signal. The above is the same as the conventional configuration of FIG. Is. The difference from the configuration of FIG. 5 is that the HFM superposition storage unit 119 and the HFM OFF signal 152 are added.

The operation of the optical data storage / reproducing apparatus configured as described above will be described with reference to FIG. A part of the optical power emitted by the laser 102 is received by the light receiving element 103.
The light is received by and the I / V converter 104 converts the current into a voltage. On the other hand, the reproduction reference voltage 105 is selected at the time of reproduction and the recording reference voltage 106 is selected at the time of recording by the analog switch 111.
In the voltage comparison unit 107, the outputs of 104 and 111 are compared, and the error signal, the fixed recording voltage 108 and the HFM superposition storage unit 119 are added by the addition unit 109 and output to the base of the transistor-113.

The HFM superposition storage unit 119 turns off the HFM for a certain period at the time of reproduction just before recording, stores the superposition amount of ON-OFF difference to the laser at this time, and adds at the time of recording the addition unit 1
09 is added. At the time of reproduction, since the data 151 is "L", the transistor-114 is turned off and the transistor-1
All 13 collector currents flow to the laser 102. When the optical output of the laser 102 decreases due to temperature change,
The error signal of the voltage comparison 107 causes the laser 102 to increase the current so that the optical output is kept constant. At the time of recording, the modulated recording data "L" and "H" are output to the data 151, which causes the transistor-114 to "OF".
F "and" ON ", laser is" emissive "and" non-emissive "
Then, the data is recorded on the information medium 501.

This timing chart is shown in FIG. HFM is turned off for a certain period during playback T12 immediately before recording
However, the change amount V1A of the superimposing amount on the laser at this time is V
z is stored in the HFM superposition storage unit 119 shown in the column V1C. Then, the recording fixed voltage unit 108 is previously provided with the HFM.
The voltage of the difference between the recording power and the reproducing power when the switch is turned off is adjusted at the time of initial adjustment.
407, the voltage Vx when the HFM is ON, the Vz of the HFM superposition storage unit 119, and the recording fixed voltage unit 108.
Vy 'is added. Here, the ON voltage of HFM and HFM
The voltage applied to the superposition storage unit 119 is the HFMOFF voltage. The voltage Vx when the HFM is on is not shown in the configuration block in FIG. 1, but is included in the output V1A of the voltage comparison unit 107, for example, the sample hold output and the voltage comparison output at the time of recording. It is output in the added form. This voltage V1A is
As described above, since the servo output based on the recording standard is delayed, the voltage corresponding to Vx becomes dominant. After that, in the servo stable period shown by T15 in FIG. 2, the output obtained by comparing the recording reference voltage and the IV conversion becomes dominant.

As described above, the voltage corresponding to the current value when the HFM in the reproducing state is added is set as a part of V1A,
The laser current is controlled by the output obtained by storing the voltage corresponding to the difference current between the state in which the HFM is added in the reproducing state and the state in which the HFM is not added, as V1C, and further adding the precisely fixed recording fixed voltage as V1B in the initial state. As a result, the rise in speed can be increased, the amount of high-frequency superimposition on the laser changes due to HFM oscillation amplitude changes, and the temperature characteristics of the semiconductor laser and HFM differ greatly. It is possible to realize high-speed and stable laser power control in which the laser power does not change at the beginning of recording even when the optical characteristics cannot be correlated.

The HFM superposition storage section can be easily realized by D / A conversion, semiconductor memory, a register for performing difference calculation, A / D conversion, etc., but the sample and hold circuit is two circuits for turning the HFM on and off. It can also be realized by preparing and using the difference signal.

Here, the timing at which the signal is taken into the HFM superposition storage section is described just before recording, but after the search before recording is completed, a timing such as a time waiting state after reproduction of necessary data does not require signal reading. It is also effective to carry out the method in 1., and depending on the configuration of the storage unit such as the non-volatile memory, it is also effective to carry out only once at startup. In addition, a separate temperature detector may be provided so that when the temperature variation exceeds a certain amount, the quality is not required so much, such as the S / N ratio of the signal that is not recorded or reproduced, so that it is sequentially performed. Good.

As described above, according to this embodiment, a laser light source for writing data on the information medium or reading the data already written on the information medium, and noise reduction at the time of reading the data. To this end, a high-frequency module for high-frequency superimposing on the laser light source, a laser HFM circuit for driving the laser light source and the high-frequency module, and a high-frequency module are turned off and turned on immediately before recording. By providing an HFM superposition storage unit that stores the voltage difference between the time and the OFF time, the rise of the recording power can be speeded up and stabilized.

(Embodiment 2) Another embodiment of the present invention will be described below with reference to the drawings. 20 in FIG.
1 is an HFM, 202 is a laser, 203 is a light receiving element, 20
4 is an I / V conversion unit, 205 is a reproduction reference voltage, 206 is a recording reference voltage, 207 is a voltage comparison unit, 208 is a fixed recording voltage unit, 209 is an addition unit, 211 is an analog switch, and 217 is another circuit. Block 218, stabilized power supply dedicated to HFM, 250 reproduction / recording switching signal, 251 CP
This is a data signal transferred from U508.

The operation of the optical data storage / reproducing apparatus constructed as above will be described with reference to FIG. A part of the optical power emitted by the laser 202 is received by the light receiving element 203.
The light is received by, and current / voltage conversion is performed by the I / V conversion 204. An analog switch 211 selects a reproduction reference voltage 205 for reproduction and a recording reference voltage 206 for recording. The voltage comparison unit 207 compares the outputs of 204 and 211,
The error signal and the recording fixed voltage 208 are added by the adder 209 and output to the base of the transistor 213. Since the data 251 is "L" at the time of reproduction, the transistor-214 is turned off, and the collector current of the transistor-213 all flows to the laser 202. When the optical output of the laser 202 decreases due to temperature change or the like, the voltage comparison 207
Error signal increases the current in the laser 202 and controls so that the optical output is kept constant. At the time of recording, the modulated recording data "L" and "H" are output to the data 251, so that the transistor 214 is turned "OFF" and "O".
N ", the laser emits light and does not emit light, and data is recorded on the information medium 501. Also, when the laser 202 emits light during reproduction, the laser emits light from the information medium 501. The HFM 201 is oscillated at a high frequency for the purpose of reducing noise due to returning light to the laser 202, and the laser 20 is passed through the capacitor 216.
2 is superposed on high frequency. Since the power source of the HFM 201 is stabilized by the HFM-dedicated stabilizing power source 218 arranged very close to the HFM 201, the HFM 201 can be operated in any mode.
Oscillation is stable, the amount of superimposition on the laser 202 is constant, and the laser power does not change at the beginning of recording. Next, the timing chart of FIG. 4 will be described. T2
1 is a reproduction mode, T22 is a recording start mode, and T2.
Reference numeral 3 shows the recording stability mode. In T22 mode, T21
The recording fixed voltage 308 adjusted at the initial adjustment is added to the voltage required for the reproduction light power in the mode, and the recording power is output. However, the voltage required for reproducing light power does not change from that at the time of initial adjustment because the stabilized power supply is used for the power supply voltage of the HFM, so the recording power in T22 mode is used.
Is stable. Laser HFM drive circuit 5 in T23 mode
The servo characteristic of 06 stabilizes the recording power by the recording reference voltage. Next, a comparison between the conventional example and the second embodiment will be described with reference to FIG. In the same figure, in the conventional case, 40 is
As shown in FIG. 3, the recording power is adjusted so as to be optimally output, but when the voltage applied to the HFM changes in the market, the recording power changes at the start of recording, as indicated by 405. Since the HFM voltage is stable in the second embodiment, the optimum recording power is output even in the market, as indicated by 406. As is apparent from FIG. 7, the optical data storage / reproducing apparatus according to the present embodiment stabilizes the recording power when the recording power rises, and has an excellent effect on the recording margin against dust and dirt. ..

As described above, this example is a countermeasure against the change in the output amplitude of the HFM being more susceptible to the change in voltage than the change in temperature. Here, when the influence of the temperature on the amplitude characteristic of the HFM is greater, 3 HFM201 to H
The stabilized power source 218 dedicated to FM is fed back as shown by a wavy line, the amplitude is detected by a circuit means such as envelope detection, and the power supply voltage is changed so that the output becomes constant, or a high frequency in the HFM is not shown. Controlling the gain and bias of the oscillation circuit is also a very effective means for stabilizing the amplitude.

As described above, according to the present invention, a laser light source for writing data on the information medium or reading the data already written on the information medium, and noise reduction at the time of reading the data. To this end, a high-frequency module for high-frequency superimposing on the laser light source, a laser HFM circuit for driving the laser light source and the high-frequency module, and an oscillation output of the high-frequency module are stably operated. As a means for achieving this, for example, by providing a stabilizing power supply dedicated to the HFM, the oscillation output of the HFM can be stabilized, the speed of the rising edge of the recording can be realized, and the power can be stabilized.

[0028]

As described above, the present invention can be applied to an information medium.
Data or data already written on the information medium.
A laser light source for reading data, a high-frequency module for high-frequency superimposing on the laser light source to reduce noise when reading data, and a laser light source and a high-frequency module for driving the laser light source. And a HFM superposition storage section for storing the difference between the currents flowing in the laser when the high frequency module is turned off immediately before recording and turning it on and off, or the oscillation output of the high frequency module. By providing the means for stabilizing, it is possible to provide an excellent optical data storage / reproducing apparatus which speeds up the start of recording and stabilizes the recording power with high accuracy.

[Brief description of drawings]

FIG. 1 is a block diagram of a laser HFM drive circuit of an optical data storage / reproduction device according to a first embodiment of the present invention.

FIG. 2 is a timing chart of a laser HFM drive circuit of the optical data storage / reproducing apparatus according to the first embodiment of the present invention.

FIG. 3 is a block diagram of a laser HFM drive circuit of an optical data storage / reproduction device according to a second embodiment of the present invention.

FIG. 4 is a timing chart of a laser HFM drive circuit of an optical data storage / reproduction device according to a second embodiment of the present invention.

FIG. 5: Laser HF of conventional optical data storage / reproduction device
M drive circuit block diagram

FIG. 6 shows a laser HF of a conventional optical data storage / reproduction device.
M drive circuit timing chart

FIG. 7: Current-optical characteristic diagram of laser when HFM is added

FIG. 8 is a block diagram of a first embodiment of the present invention, a second embodiment of the present invention and a conventional optical data storage / reproduction device.

[Explanation of symbols]

 501 information medium 102 laser light source 101 high frequency module (HFM) 506 laser HFM drive circuit 119 HFM superposition storage unit 218 HFM dedicated stabilizing power supply

Claims (3)

[Claims] 1. An information medium, a laser light source for writing data on the information medium or for reading data already written on the information medium, and noise reduction at the time of reading the data. A high-frequency module for high-frequency superimposing on the laser light source, a laser high-frequency module drive circuit for driving the laser light source and the high-frequency module, and a high-frequency module turned off and turned on immediately before recording. And the delay when OFF
An optical data storage / reproduction device having a high-frequency module superimposition storage unit that stores a current difference that drives the laser. 2. A current difference for driving the laser at the time of turning on the high frequency module and turning it off and at the time of turning off the high frequency module at the timing at which the signal reading is not required at the time of start-up or during the reproducing operation before the recording operation. An optical data storage / reproduction device characterized by: 3. An information medium, a laser light source for writing data on the information medium or for reading data already written on the information medium, and for reducing noise at the time of reading the data. A high-frequency module for high-frequency superimposing on the laser light source, a laser high-frequency module drive circuit for driving the laser light source and the high-frequency module, and an oscillation output amplitude of the high-frequency module. An optical data storage / reproduction device having an amplitude stabilizing means for maintaining a constant value.