JPH0512697A - Optical disk device - Google Patents

Abstract

PURPOSE:To prevent an increase in follow-up errors and a servo loop oscillation by correcting the servo gain in accordance with the pattern of recorded data and recorded pulse width. CONSTITUTION:A channel signal S12 of recorded data is inputted to a servo gain correction section 20. Then, the servo gain correction section 20 outputs a correction voltage S20. This correction voltage 20 has an average voltage value in accordance with the pattern of the channel signal S12 and recorded pulse width, inputted to a driving section 18 and a servo gain correction is performed in accordance with the pattern of the recorded data and recorded pulse width.

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 / reproducing data on / from an optical disk (for example, a write-once optical disk device capable of recording only once, a rewritable optical disk device capable of rewriting a plurality of times, and rewritable). (E.g., magneto-optical disk device), and more particularly to stabilization of focus control and tracking control during data recording.

[0002]

2. Description of the Related Art Conventionally, as a technique of this kind of field, Kazuo Terada, "Points of Design of Optical Pickup System" [6]
(Sho 59-10-31) Japan Industrial Technology Center, P. 1
51,152,161. Hereinafter, description will be given with reference to the drawings. FIG. 2 is a schematic configuration block diagram of the conventional optical disk device described in the above document.

This optical disk device has a control section 1 for outputting recording data D1, a modulation section 2 for performing, for example, 2-7 rate modulation to generate a channel signal S2, and a laser beam from a semiconductor laser based on the channel signal S2. And a laser drive unit 3 for emitting L. Further, a spindle motor 5 for rotating the optical disc 4 for recording the recording data D1 is provided, and a laser beam L emitted from the laser driving unit 3 is irradiated onto the optical disc 4 in the vicinity thereof, and the optical disc 4 of the laser beam L is emitted. Reflected light (or transmitted light) from
Optical head unit 6 which outputs as an output light, a signal reproducing unit 7 which outputs a focus error signal and a tracking error signal based on the output light, and a predetermined focus servo gain and tracking based on the focus error signal and the tracking error signal. A drive unit 8 is provided for driving the optical head unit 6 in the focus direction and the tracking direction with a servo gain. The signal reproducing unit 7 has a function of converting the output light from the optical head unit 6 for reading the data recorded on the optical disc 4 into an electric signal, and the output side thereof is controlled via the demodulating unit 9. Part 1 is connected.

Next, the operation will be described with reference to Table 1 showing the modulation / demodulation conversion 2-7.

[0005]

[Table 1]

The optical disk 4 is driven by the spindle motor 5.
When data is recorded on the optical disc 4 by rotating the optical disc 4, first, when the recording data D1 output from the control unit 1 is input to the modulation unit 2, as shown in Table 1, for example, the recording data D1 2-7 rate modulation for converting the bit string (A) into the channel code bit string (B) is performed, and the channel signal S2 corresponding to "1" and "0" of this bit string is output to the laser drive unit 3. . The laser drive unit 3 emits the laser light L according to the channel signal S2. The laser light L is irradiated onto the optical disc 4 through the optical head unit 6, and the channel signal S of the recording data D1 is recorded.
2 is recorded on the optical disc 4.

After that, the reflected light (or transmitted light) of the laser light L applied onto the optical disk 4 is output to the signal reproducing section 7 as output light through the optical head section 6. The signal reproducing unit 7 detects a focus error (focusing error) and a tracking error (trace error with respect to the track of the optical disc 4) based on the output light, generates a focus error signal and a tracking error signal, and outputs the focus error signal and the tracking error signal. The tracking error signal is output to the drive unit 8. The drive unit 8 drives the optical head unit 6 in the focus direction (Y direction) and the tracking direction (X direction) with a predetermined focus servo gain and tracking servo gain based on the focus error signal and the tracking error signal, and at the time of recording. Focus control and tracking control are performed.

At the time of normal data recording, recording data D1
Is not a constant pattern, the average value of the bit string of the channel signal S2 shown in Table 1 (1000100
The servo gain is set as a duty of 25% based on (01 repetition). Therefore, when the data is recorded in the normal pattern, the duty is approximately 25%, so that the operation is performed normally.

In the conventional optical disk device, a semiconductor laser is provided in the optical head section 6 of FIG.
There is also a structure in which the laser beam L is output from the semiconductor laser according to the control signal output from the semiconductor laser.

[0010]

However, in the optical disc device having the above-mentioned configuration, for example, during the test recording or in the disc defect search mode for searching for a defect of the optical disc 4, for example, a bit string (10000000).
When recording data of a special pattern of (1 repetition) or (1001001 repetition), the duty greatly changes from 25%. Therefore, as described above, the servo gain set with the duty of 25% during normal data recording as a reference cannot operate normally. For example,
When the special pattern data is (100000001 repetitions), the servo gain is significantly reduced, and (1001
(Repetition of 001), the servo gain increases. Therefore, when the servo gain is remarkably reduced, the tracking error in the focus control or tracking control is increased, and when it is increased, the oscillation of the servo loop occurs, which causes the optical head unit 6 to runaway in the worst case. Then
There was a problem of damage.

Further, such a problem is more serious when the duty ratio is changed such that the laser-on time of "1" is shortened at the inner circumference and lengthened at the outer circumference as a correction of the linear velocity at the inner and outer circumference positions of the disk. It gets worse. The present invention provides an optical disk device that solves the problems of the prior art described above, such as increase in tracking error and oscillation of servo loop.

[0012]

In order to solve the above-mentioned problems, a first aspect of the present invention is directed to a laser drive unit for emitting a laser beam according to recording data, and a reflected light obtained by irradiating the laser beam onto an optical disk. Alternatively, an optical head unit that outputs output light based on transmitted light, a signal reproducing unit that outputs a focus error signal and a tracking error signal based on the output light, and a predetermined focus servo based on the focus error signal and the tracking error signal In an optical disc device including a drive unit that drives the optical head unit in a focus direction and a tracking direction with a gain and a tracking servo gain, both the gain of the focus servo gain and the tracking servo gain, or one of the gains is set. , The recording data pattern and recording pulse width The servo gain correction means for correcting in accordance is provided.

According to a second aspect of the invention, instead of the laser drive section and the optical head section of the first aspect, laser light is irradiated onto the optical disk according to recording data, and output light is output based on the reflected light or transmitted light. An optical head unit is provided. According to a third aspect of the present invention, the servo gain correction means of the first or second aspect is configured to correct the gain by analog-processing the channel signal generated by modulating the recording data or the output light. There is.

[0014]

According to the first or second aspect of the invention, since the optical disk device is configured as described above, the servo gain correction means sets either one or both of the focus servo gain and the tracking servo gain, Correction is made according to the pattern of recording data and the recording pulse width.
As a result, the servo gain is corrected according to, for example, the pattern of the recording data, the switching between the inner and outer circumference duties, and the focus control and tracking control are stabilized.

According to the second invention, the servo gain correcting means adjusts one or both of the focus servo gain and the tracking servo gain by analog processing. As a result, the servo gain is accurately corrected according to the pattern of recording data and the recording pulse width. Therefore, the above problem can be solved.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment FIG. 1 is a schematic block diagram of an optical disk device showing a first embodiment of the present invention.

This optical disk device controls the entire device and outputs the recording data D11, and the recording data D11 is subjected to the 2-7 rate modulation in the same manner as in the conventional case in order to improve the recording density. Channel signal S
A modulator 12 for generating 12 and a laser driver 13 composed of a semiconductor laser or the like for emitting a laser beam L according to a channel signal S12 are provided. Further, a spindle motor 15 for rotating the optical disc 14 for recording the record data D11 is provided, and the laser light L emitted from the laser driving unit 13 is irradiated on the optical disc 14 in the vicinity thereof, and its reflected light (or transmitted light) is emitted. 16) which is composed of a mirror and an objective lens for outputting
The output light is received by, for example, a two-division photodetector to generate a focus error signal from the difference signal, and the output light is received by, for example, a two-division photodetector to generate a tracking error signal from the difference signal. The signal reproducing unit 17 is provided.

The signal reproducing section 17 has a function of converting the output light from the optical head section 16 into an electric signal in order to reproduce the data recorded on the optical disc 14, and its output side has a signal line. The drive unit 18 is connected via P and the demodulation unit 19 is also connected. Based on the focus error signal and the tracking error signal, the driving unit 18 causes the optical head unit 16 to move in the tracking direction (X direction) and the focus direction (Y direction) via the signal line Q with a constant focus servo gain and tracking servo gain. It has the function of driving to. The demodulation unit 19 has a function of demodulating the output of the signal reproduction unit 17 according to, for example, Table 1 above, and the output side thereof is connected to the control unit 11.

Further, one or both of the focus servo gain of the focus servo system and the tracking servo gain of the tracking servo system are selected according to the pattern of the recording data and the recording pulse width (for example, depending on the switching of the inner / outer duty). A servo gain correction unit 20 for performing the correction is connected between the modulation unit 12 and the drive unit 18.

FIG. 3 is a diagram showing the internal structure of the servo gain correction section 20 and the main section of the drive section 18 in FIG. 1 which constitute the servo gain correction means. 3, the servo gain correction unit 20 smoothes the channel signal S12 based on the output of the switch circuit 21 and the switch circuit 21 that outputs a signal for charge / discharge control based on the channel signal S12, and outputs the signal of the channel signal S12. The time constant circuit 22 outputs a correction voltage S20 in which the average voltage value decreases as the section of "1" (recording pulse width or pulse interval) is longer. The switch circuit 21 includes an open collector inverter (OC) 21a and the like. The time constant circuit 22 includes a resistor 22a connected to the output side of the switch circuit 21, a resistor 22b connected between the resistor 22a and the reference voltage VREF, and a capacitor 22c connected between the resistor 22a and the ground potential GND. It consists of and.

Further, in the drive unit 18, the gain changes almost proportionally in accordance with the correction voltage S20 from the servo gain correction unit 20, and the signal reproduction unit via the signal line P for the focus error signal and the tracking error signal. AGC section (Auto Gain Control) 3 connected to the optical head section 16 via a signal line Q
Has 0. The AGC unit 30 includes an operational amplifier 31 having a non-inverting input (+) side connected to the reference voltage VREF and an output side connected to the signal line Q, and between the output side of the operational amplifier 31 and the inverting input (−) side. The connected feedback resistor 32, the FET 33 that functions as a variable resistance input resistor of the operational amplifier 31, and has the source (S) and the drain (D) connected to the signal line P and the inverting input (−) side, respectively, and the FET 33. (G) and the input resistance 34 connected between the output ends of the servo gain correction section 20. Where F
A gain adjusting unit is configured with the ET 33 and the input resistor 34 as main components.

The servo gain correction section 20 as described above,
Servo gain correcting means is configured by the gain adjusting unit of the AGC unit 30. Next, referring to FIGS. 4 and 5, the operations of FIGS. 1 and 3 will be described by dividing them into operation examples (1) to (3).

FIG. 4 is an operation waveform diagram of FIG. 1, showing the waveform of the recording data D12, the waveform of the channel signal S12, the emission state of the laser beam L, and the emission state of the laser beam L at low power. ing. FIG. 5 is an operation waveform diagram of the servo gain correction unit 20 in FIG.

(1) Normal data recording operation For example, the spindle motor 15 drives the optical disk 14
When data is recorded on the optical disk 14 by rotating the optical disc, the recording data D11 output from the control unit 11 as shown in FIG. 4 is input to the modulation unit 12. In the modulator 12, as shown in Table 1 above, for example, 2-7 rate modulation is performed to modulate the bit string (A) of the recording data D11 into the channel code bit string (B). The channel signal S12 as shown in FIG. 4 corresponding to 0 ″ is output to the laser driving unit 13. As shown in FIG. 4, the laser drive unit 13 is turned on when the bit of the channel signal S11 is “1” to emit the laser light L, and when the bit is “0”, the laser drive L is off. A low power laser beam L that does not stop the light emission or records data is emitted.

The laser light L is input to the optical head unit 16 and irradiated onto the optical disc 14, and the channel signal S12 of the recording data D11 is recorded on the optical disc 14. At this time, even during data recording, correct recording cannot be performed unless proper focusing and tracking are performed. Therefore, the reflected light (or transmitted light) of the laser light L radiated onto the optical disk 14 is reflected by the optical head unit. The output light is output to the signal reproducing unit 17 via 16.

The signal reproducing section 17 detects a focus error and a tracking error based on the output light of the optical head section 16 to generate a focus error signal and a tracking error signal. At this time, at the time of recording, the laser light L becomes on / off or on / constant low power according to the channel signal S12, so that the focus error signal and the tracking error signal obtained by the signal reproducing unit 17 are the channel signal. It changes according to the section (1) (recording pulse width and pulse interval) of S12 and is not constant. Normally, the on / off frequency is 1 to 10 MHz, and the focus error signal and tracking error signal used as a servo are about 10 KHz or less, so the average value of on / off is the focus error signal and the tracking error signal. Become.

The focus error signal and the tracking error signal are output to the drive section 18 via the signal line P. In the drive unit 18, the optical head unit 16 is driven in the tracking direction (X direction) and the focus direction (Y direction) with a constant focus servo gain and tracking servo gain based on the focus error signal and the tracking error signal, and the optical disc 14 is driven. The laser light L is made to follow the upper track.

(2) Data recording operation when a special pattern or the like is used When the recording data D11 of the special pattern is output from the control unit 11, the recording data D11 is modulated by the modulation unit 12 and the servo gain is obtained as the channel signal S12. Correction unit 2
It is input to the open collector inverter 21a in 0. Then, the channel signal S12 is inverted by the open collector inverter 21a, and the inverter output is smoothed by the time constant circuit 22.

That is, the open collector inverter 21a
When the channel signal S12 input to is to "1", it is inverted to "0", and the resistor 2 in the time constant circuit 22
2a and the capacitor 22c are discharged according to the time constant. Conversely, when the channel signal S12 is "0", it is inverted and becomes "1". At this time, the output of the open collector inverter 21a is turned off due to the open collector, so that the resistor 22 in the time constant circuit 22 is
b and the capacitor 22c are charged according to the time constant. In this way, the servo gain correction unit 20 smoothes the channel signal S12 of the recording data D11, and as shown in FIG. 5, the correction voltage having the average voltage value VAVE according to the pattern of the recording data D11 and the recording pulse width. Outputs S20. Here, the average voltage value VAVE of the correction voltage S20 is VAVE = (VH + VL) / 2. Note that VH is the maximum voltage value and VL is the minimum voltage value. The correction voltage S20 of the servo gain correction unit 20 is input to the AGC unit 30 in the drive unit 18 and the FET via the input resistor 34.
33 is applied to the gate.

In the AGC section 30, when the voltage value of the correction voltage S20, which is the gate voltage of the FET 33, decreases, the resistance between the source (S) and the drain (D) of the FET 33, which is the input resistance of the operational amplifier 31, increases, and the operation is performed. Amplification factor Rf / Rin of the amplifier 31 (where Rf is the resistance value of the feedback resistor 32, Rin is the source-drain resistance value of the FET 33)
Is small. Conversely, when the voltage value of the correction voltage S20 increases, the input resistance value Rin of the operational amplifier 31 decreases and the amplification factor Rf / Rin of the operational amplifier 31 increases, thereby controlling the gain. Therefore, the longer the period of "1" of the channel signal S12 is, the lower the average voltage value VAVE of the correction voltage S20 is.
The gain between the signal lines P and Q by the GC unit 30 also decreases. On the contrary, the shorter the “1” section of the channel signal S12, the higher the average voltage value VAVE of the correction voltage S20,
As a result, the gain between P and Q increases.

Therefore, the longer the "1" section (that is, the laser emission time) of the channel signal S12, the larger the amount of light obtained as the focus error signal and the tracking error signal, and the higher the servo gain of each, but the servo gain. The correction voltage S20 from the correction unit 20 decreases as the “1” section of the channel signal S12 becomes longer,
Since the gain between P and Q is lowered, the servo gain can be totally corrected.

When the recording data D11 is not a special pattern, for example, the recording pulse width is generally narrow on the inner circumference and wide on the outer circumference because the linear velocities on the inner and outer circumferences of the disc are different. Even in such a case, the servo gain is automatically corrected. That is, when the recording pulse width of the recording data D11 is narrowed, the laser emission time is shortened,
Although the amount of light obtained as the focus error signal and the tracking error signal is small and the respective servo gains are low, the correction voltage S20 from the servo gain correction unit 20 becomes
The section of "1" of the channel signal S12 becomes short because it becomes high, so that the gain between P and Q can be made high and the servo gain can be totally corrected.

(3) Operation during reproduction When reading the data recorded on the optical disc 14, the optical head unit 16, the signal reproducing unit 17, and the driving unit 18 form a focus servo system and a tracking servo system, and the optical head Based on the output light output from the unit 16,
Focus control and tracking control are performed. While performing this focus control and tracking control, output light according to the data recorded on the optical disc 14 is obtained.
The output light is converted into an electric signal in the signal reproducing section 17, and then input to the demodulating section 19. In the demodulation section 19, the output of the signal reproduction section 17 is demodulated as shown in (B) to (A) of Table 1 and sent to the control section 11.

The first embodiment has the following advantages. In this embodiment, the servo gain correction unit 20 is provided, and the AGC unit 30 is provided with the FET 33 as the input resistance of the operational amplifier 31, and the correction voltage S20 is applied as the gate voltage of the FET 33 via the input resistance 34. ing. Therefore, the channel signal S1
The servo gain in the AGC unit 30 is automatically adjusted by the correction voltage S20 whose average voltage value changes according to the pattern of 2 (that is, the recording data D11) and the recording pulse width. The servo gain can be totally corrected according to the width (switching of the duty inside and outside the disk) (that is, according to the signal levels of the focus error signal and the tracking error signal). Therefore, even if the amount of light obtained as the focus error signal and the tracking error signal changes according to the pattern of the recording data D11 and the recording pulse width, the servo gain is automatically corrected and the output of the drive unit 18 is stabilized, It is possible to prevent the tracking error of the optical head unit 16 from increasing and the servo loop from oscillating.

In particular, in this embodiment, the servo gain correction section 20 is composed of the switch circuit 21 and the time constant circuit 22, and the gain in the AGC section 30 is adjusted by changing the gate voltage of the FET 33. The servo gain can be surely corrected with a simple structure.

Second Embodiment FIG. 6 is a schematic block diagram of an optical disk device showing a second embodiment of the present invention. Elements common to those in FIG. 1 are designated by common reference numerals. ing. In this optical disk device, instead of the laser drive unit 13, the optical head unit 16 and the servo gain correction unit 20 of FIG. 1, a laser drive unit 13A, an optical head unit 16A and a servo gain correction unit 20A having different circuit configurations are provided. There is.

The laser driving unit 13A uses the optical head unit 1 based on the channel signal S12 output from the modulating unit 12.
Control signal S13 for emitting laser light L from 6A
It has a function of outputting A to the optical head unit 16A.
The optical head unit 16A has a function of emitting a laser beam L, irradiating the laser beam L on the optical disc 14 based on the control signal S13A, and outputting the reflected light (or transmitted light) as output light. There is.

The servo gain correction unit 20A selects one of the focus servo gain of the focus servo system and the tracking servo gain of the tracking servo system based on the output light of the optical head unit 16A supplied through the signal reproduction unit 17. A correction voltage S20A for correcting one or both of them according to the pattern of the recording data and the recording pulse width (for example, it changes according to the switching of the inner / outer circumference duty).
Is output to the drive unit 18.

FIG. 7 is a block diagram showing the optical head portion 16A in FIG. The optical head unit 16A is mounted on an actuator 55, and when the actuator 55 is driven by the drive unit 18 in FIG. 6, the optical head unit 16A is moved in the tracking direction (X direction) or the focus direction (Y direction). ) Is configured to move. The optical head unit 16A includes the semiconductor laser 41 and the beam splitter 4.
2, 43, objective lens 44, quarter-wave plate 45, polarization beam splitter 46, photodetector 47 for outputting reproduction signal detection signal PD1, photodetector 48 for outputting reproduction signal detection signal PD2, laser mirror 49, tracking servo control Output signal from the semiconductor laser 41, for example, a two-division photodetector 50 for outputting the detection signal TE, a cylindrical lens 51, a two-division photodetector 52 for outputting the detection signal FE for focus servo control, and the like. The photodetector 53 outputs a laser power detection signal PD0 for controlling the laser power.

The semiconductor laser 41 is connected to the laser driving unit 13A shown in FIG. 6 and has a function of outputting the laser beam L in accordance with a control signal S13A output from the laser driving unit 13A. Photo detectors 47, 48, 50,
The output side of 52 is connected to the signal reproducing section 17 of FIG. The signal reproducing unit 17 has a function of inputting the detection signal FE output from the photo detector 52 and the detection signal TE output from the photo detector 50, and generating a focus error signal and a tracking error signal.

FIG. 8 is a block diagram showing the servo gain correction means in FIG. This servo gain correction means is shown in FIG.
The servo gain correction section 20A and the AGC section 30 in the drive section 18 which is the same as that in FIG. The servo gain correction unit 20A includes an operational amplifier 25 and the operational amplifier 2
5, a feedback resistor 26 and a feedback capacitor 27 connected in parallel between the output side and the inverting input (-) side.
On the inverting input (-) side of the operational amplifier 25, the power supply voltage VC
The light receiving diode 54 to which C is applied is connected, and the laser power detection signal PD0 output from the photo detector 53 of FIG. 7 enters the light receiving diode 54.
A reference voltage VRE is provided on the non-inverting input (+) side of the operational amplifier 25.
F is applied, and its output side is connected to the input resistor 34 in the AGC section 30.

The operation of the optical disk device of FIG. 6 configured as above will be described. When the recording data D11 as shown in FIG. 4 is output from the control unit 11 in FIG. 6, it is modulated by the modulation unit 12, and the channel signal S12 is sent to the laser driving unit 13A. The laser driving unit 13A outputs a control signal S13A corresponding to the channel signal S12 to the optical head unit 16A.

When the control signal S13A is input to the optical head section 16A, the semiconductor laser 41 produces a laser beam L as shown in FIG.
It is irradiated onto the optical disc 14 via the beam line 4. At this time, the light split by the beam splitter 42 enters the photodetector 53, and the detection signal PD0 is obtained. The detection signal PD0 is received by the light receiving diode 54 of FIG. 8 and input to the servo gain correction unit 20A. The detection signal PD0 input to the servo gain correction unit 20A is supplied to the operational amplifier 25.
Is converted into a voltage, amplified and smoothed by the feedback resistor 26 and the feedback capacitor 27, and the correction voltage S20A is output to the input resistor 34 in the AGC unit 30.

Here, the feedback resistor 26 and the feedback capacitor 27.
Sets the detection signal PD0 corresponding to the channel signal S12 output from the modulator 12 to be sufficiently smoothed and set to a time constant equal to or higher than the response frequency of the servo loop. When the resistance value of the feedback resistor 26 is R6 and the capacitance value of the feedback capacitor 27 is C27, the frequency of the channel signal S12 is 1 MHz to 1
Since the response frequency of the servo loop is generally 10 KHz or less at 0 MHz, it is appropriate to set the time constant R26 × C27 so that R26 × C27 = 1 / 2πf f ≈100 KHz to 500 KHz.

Since the servo loop does not respond at high speed as described above, it is of course possible to input it to the AGC unit 30 without smoothing it like the correction voltage S20A in this embodiment. This is because the AGC unit 30 changes the gain at high speed with respect to a signal input as an ON / OFF signal without being smoothed, but the servo loop does not respond, and as a result, the servo loop gain is smoothed. .

As described above, in the servo gain correction section 20A, the higher the laser power entering the light receiving diode 54, that is, the longer the total time occupied by "1" in the channel signal S12, the output correction voltage S2.
0A goes down. On the contrary, the output correction voltage S20A increases as the incident laser power decreases, that is, as the total time occupied by "0" in the channel signal S12 increases. The correction voltage S20A is input to the AGC unit 30, and the servo gains of the focus error signal and the tracking error signal are corrected as in the first embodiment. As a result, the same advantages as the first embodiment can be obtained.

Third Embodiment FIG. 9 is a circuit diagram of a servo gain correction section showing a third embodiment of the present invention. The servo gain correction unit 60 is provided in place of the servo gain correction unit 20 shown in FIGS. The servo gain correction unit 60 is the open collector 22 in the servo gain correction unit 20 of FIG.
Instead of a and the resistor 21c, a normal operational amplifier 61 (for example, 324) is provided, the input end of the channel signal S12 is connected to the inverting input (−) side, and the non-inverting input (+) side is connected to, for example, Reference voltage VREF = 5V and ground potential GND
A bleeder resistor 62 (for example, 10 KΩ) and a bleeder resistor 63 (for example, 10 KΩ) that are connected between them and supply a predetermined reference voltage to the operational amplifier 61 are connected.

Such a servo gain correction unit 60 is shown in FIG.
Alternatively, the same operation and effect as those of the first and second embodiments can be obtained by providing the device of FIG.

Fourth Embodiment FIG. 10 is a circuit diagram of a servo gain correction section showing a fourth embodiment of the present invention. This servo gain correction unit 70
The one provided in FIG. 1 or FIG. 6, for example, the reference voltage V
A resistor 71, which is sequentially connected between REF and the ground potential GND,
NPN type bipolar transistor 72 and resistor 73
And an input resistor 74 connected between the base of the bipolar transistor 72 and the input end of the channel signal S12.
And a capacitor 75 connected between the connection point of the resistor 71 and the bipolar transistor 72, that is, between the output end of the correction voltage S20 and the ground potential GND. Even if such a servo gain correction unit 70 is provided in the device of FIG. 1 or 6, the same operation and effect as those of the first and second embodiments can be obtained.

The present invention is not limited to the illustrated embodiment, but various modifications can be made. The following are examples of such modifications. (A) In the above embodiment, the modulation method of the modulator 12 is "1".
2-7 rate modulation in which the interval between "1" and "1" is 2 at the minimum and 7 at the maximum. However, the present invention is not limited to this, and for example, 4-5 rate in which 4 bits of original data are replaced with 5 bits. 3PM (Th
Ree Position Modulation) or the like may be used.

(B) The servo gain correcting means of FIGS. 3 and 8 corrects both the focus servo gain and the tracking servo gain in accordance with the pattern of the recording data D12 and the recording pulse width. Only one of the gain and the tracking servo gain may be corrected.

(C) In the servo gain correction section 20 of FIG. 3, the switch circuit 21 uses an open collector inverter 21a as an LS067 or an operational amplifier (for example, 339).
Etc. may be used. Further, the time constant circuit 22 is
The reference voltage VREF and the ground potential GND may be composed of other power supply voltages. Further, the servo gain correction units 20, 20
The A, 60, and 70 may have other configurations.

(D) Servo gain correction section 20, 20A,
The outputs of 60 and 70 are the correction voltages S20 and S20A, but the current output may be taken into consideration depending on the configuration of the AGC unit 30 and the like. (E) In the second embodiment, the laser power detection signal PD0
Although the method of correcting the servo gain during recording by using the above is described, a signal that is the return light from the optical disk 14 and the voltage of which changes according to the amount of light, for example, the PD shown in FIG.
The same servo gain correction is possible by an ID signal (preformat signal) which is an addition signal of 1 and PD2, or an addition signal of the two-division type photodetectors 50 and 52 which generate a focus error signal FE and a tracking error signal TE. Is.

(F) Although the AGC unit 30 of the above embodiment is provided in the drive unit 18, the servo gain correction unit 20 or 20 is provided.
It is also possible to provide it in A. The type of the FET 33 can be set variously, and the FET is used as a gain adjusting unit.
It is also possible to set a configuration other than the above. Furthermore, AGC
The unit 30 can also be configured using, for example, an analog divider or a multiplier.

(G) Even if a light source such as a semiconductor laser is provided in the optical head portion 16 shown in FIG. 1 and the control shown in FIG. 6 is performed,
The same operation and effect as those of the first embodiment can be obtained.

[0056]

As described in detail above, according to the first and second aspects of the present invention, the servo gain correcting means causes one or both of the focus servo gain and the tracking servo gain to be recorded data. The pattern is corrected according to the pattern and the recording pulse width. Therefore, when recording the data of the special pattern, when the special pattern occurs in the normal time, or when the recording pulse width changes by switching the duty according to the linear velocity of the inner and outer circumferences of the disk, etc. The servo gain is set according to the pattern of the recording data and the recording pulse width (switching of the inner / outer duty) to enable stable focus control and tracking control. As a result, the servo gain is corrected by analog processing that can reliably prevent increase in tracking error and servo loop oscillation in conventional focus control or tracking control. Also, the correction can be performed easily and accurately according to the recording pulse width.

According to the third invention, since the servo gain correcting means is constituted by providing the time constant circuit, the switch circuit and the gain adjusting section, the same effect as the first invention can be obtained. It is possible to expect an effect that the servo gain can be surely corrected with a simple configuration.

[Brief description of drawings]

FIG. 1 is a schematic configuration block diagram of an optical disk device showing a first embodiment of the present invention.

FIG. 2 is a schematic block diagram of a conventional optical disc device.

FIG. 3 is a circuit diagram of servo gain correction means in FIG.

4 is an operation waveform diagram of FIG. 1. FIG.

FIG. 5 is an operation waveform diagram of FIG.

FIG. 6 is a schematic block diagram of an optical disk device showing a second embodiment of the present invention.

FIG. 7 is a configuration diagram of an optical head unit in FIG.

FIG. 8 is a circuit diagram of servo gain correction means in FIG.

FIG. 9 is a circuit diagram of a servo gain correction unit showing a third embodiment of the present invention.

FIG. 10 is a circuit diagram of a servo gain correction unit showing a fourth embodiment of the present invention.

[Explanation of symbols]

13,13A Laser drive unit 14 Optical disc 16,16A optical head 17 Signal reproduction section 18 Drive 20, 20A, 60, 70 Servo gain correction unit

Claims (3)

[Claims] 1. A laser drive unit for emitting a laser beam according to recording data, an optical head unit for irradiating the optical disc with the laser beam and outputting an output beam based on a reflected beam or a transmitted beam, and the output beam. A signal reproducing unit that outputs a focus error signal and a tracking error signal based on
An optical disc apparatus comprising: a drive unit that drives the optical head unit in a focus direction and a tracking direction with a predetermined focus servo gain and tracking servo gain based on the focus error signal and the tracking error signal. Both gain of tracking servo gain, or one of them,
An optical disk device, comprising: a servo gain correction unit that corrects according to a pattern of the recording data and a recording pulse width. 2. An optical head unit for irradiating a laser beam onto an optical disk according to recording data and outputting output light based on reflected light or transmitted light thereof, and outputting a focus error signal and a tracking error signal based on the output light. An optical disc device comprising: a signal reproducing unit for driving the optical head unit in a focus direction and a tracking direction with a predetermined focus servo gain and tracking servo gain based on the focus error signal and the tracking error signal. , Both the focus servo gain and the tracking servo gain, or one of the gains,
An optical disk device, comprising: a servo gain correction unit that corrects according to a pattern of the recording data and a recording pulse width. 3. The optical disk device according to claim 1, wherein the servo gain correction means corrects the gain by analog-processing a channel signal generated by modulating the recording data or the output light. An optical disk device having a configuration.