JPH0916983A - Focus control method in information recording/ reproducing device - Google Patents

Abstract

PURPOSE: To stably perform focus servo control even when a light spot is shifted in the jitters direction, particularly an optical head is moved in the radial direction of a disk such as in the case of kicking and seeking by optimizing the gain of at least an amplifier. CONSTITUTION: A preamplifier(PA) 9 operates a signal detected from reflected light from the optical disk(PD) 1 by an optical pickup(PU) 2 to output focus error signal FEO, etc. A memory controller 10 measures the signal FEO plural times when the PU 2 is moved in the radial direction of the PD 1, and optimizes the gain of at least one among plural amplifiers in the PA 9 according to the measured result, and controls the PU 2 through a motor driver 4. Thus, even when the spot of the reflected light incident on the PU 2 is shifted in the jitters direction, particularly the PU 2 is moved in the radial direction of the PD 1 such as in the case of kicking and seeking, an adverse effect due to a mixture of a groove leak-in component is suppressed, and the focus servo control is performed stably.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to appropriate control of an optical disk recording / reproducing apparatus for recording / reproducing a signal to / from a disk-shaped recording medium or a servo control mechanism of a recording / reproducing head of the optical disk reproducing apparatus. CD
(Compact disc), DVD high density (digital video disc) MD (mini disc) and PC (phase change type)
The present invention relates to a light beam focus control method in an information recording / reproducing apparatus for recording / reproducing data on / from a disc or the like.

[0002]

2. Description of the Related Art In general, in this type of information recording / reproducing apparatus, taking MD as an example, tracking control and focus control of an optical head are performed so that data can be accurately written and read during recording and reproduction. I have to. Such control is performed by controlling the optical head by a so-called servo control circuit. That is, the output power of the laser that gives a light beam spot to the disc at the time of recording (hereinafter referred to as laser power) is adjusted in multiple stages according to the wattage specified by the disc, and at the time of reproduction, several types with different reflectances (pre-mastered and The laser power is made variable in multiple steps with respect to the (MO) disc, and the gains of the tracking error signal and the focus error signal are switched in order to make the reproduction light proper, and the offset of these error signals is changed every time this switching is performed. Adjust. Further, at this time, it is necessary to accurately adjust the adjustment target such as offset and balance of the tracking error signal and the focus error signal in consideration of compatibility with other devices.

The servo control circuit of the information recording / reproducing apparatus is constructed as follows. Four sensors A, B, C and D divided into four by the astigmatism method in the optical head or the optical pickup included in the optical head (see FIG. 5)
I / V conversion is performed on each of the output signals and the focus error signal basically represented by A + C-B-D is generated from the amplified output. In addition, a tracking error basically represented by EF is generated from the output obtained by I / V converting and amplifying the output signals of the two sensors of E and F of the 3-beam method (A, B, C, D). , E, F denote both the six sensors themselves and their output voltage). These error signals are given to the A / D converter to be digital signals, and the digital servo processing is performed by the servo control circuit.
The output is output through the D / A converter, and the motor drive circuit drives the focus coil and the tracking coil. Further, the focus error signal FEO is subjected to balance adjustment among a plurality of sensor output signals and offset adjustment of the signal level in the calculation process.

[0004]

Here, for example, for a four-division ABCD sensor that generates a focus error signal under the influence of aging, the spot of the reflected light of the laser beam is perpendicular to the optical axis, In addition, if it deviates in the jitter direction (track running direction on the disc), the level of the focus error signal will decrease during track crossing due to the influence of the groove between tracks (land part between tracks) or adjacent pits, and tracking error will occur. A signal similar to the signal is mixed in the focus error signal, and the operation of the focus servo control system tends to become unstable when the optical head moves in the radial direction of the disk, especially when kicking or seeking. There was a problem.

When the focus servo control is on (closed loop) and the tracking servo control is off (open loop) and the spindle motor rotates, the focus error signal FEO generally indicates eccentricity of the disk as shown in FIG. Thus, the leak component of the groove that repeatedly changes every two rotations is included.
The leakage component of the groove as a disturbance is 300 rpm for one rotation.
If m, the rotation frequency is 50 Hz, and one cycle is 100
It is Hz, and the frequency is sufficient to respond even if the loop gain intersection of the servo system is set to 1 kHz. The same applies when the track cross frequency is low. If the vibration of the spindle motor or the surface wobbling component of the disk is added to this as a disturbance, the optical pickup itself will vibrate (vibrate) in the focus direction, and the focus servo control may be lost in the worst state. is there.

In view of the above-mentioned conventional problems, the present invention moves the optical head in the radial direction of the disk even when the spot of the reflected light incident on the optical head deviates in the jitter direction, especially at the time of kick or seek. It is an object of the present invention to provide a focus control method in an optical disc recording / reproducing apparatus, which can stably perform focus servo control when performing. The "optical disc recording / reproducing device" means a disc device having one or both of an optical disc recording function and an optical disc reproducing function.

[0007]

According to one aspect of the present invention, in order to achieve the above object, a plurality of output signals of a plurality of divided sensors for receiving reflected light of a laser beam from a disk are amplified. A means for controlling the gain of at least one of the amplifiers is provided, and the gain (amplification degree) of the at least one amplifier is optimized according to the measurement result of the focus error signal.

That is, according to one aspect of the present invention, there is provided an optical disc recording / reproducing apparatus for recording information on a disc-shaped optical recording medium and / or reproducing the information recorded on the disc-shaped optical recording medium. And a means for rotating the disk, an optical head for recording / reproducing data on / from the disk by a laser beam, a plurality of sensors for receiving reflected light of the laser beam from the disk, and the sensor. A plurality of amplifiers for amplifying each of the plurality of output signals, and means for positioning the optical head with respect to the track of the disk by generating and feeding back a tracking error signal by calculation of the output signals of the plurality of amplifiers. , A focus error signal is generated by calculating the output signals of the plurality of amplifiers and fed back to position the optical head in the focus direction. Means for recording and reproducing information by exchanging signals with the optical head, and modulating and demodulating means for modulating and demodulating the recording and reproducing signals, and means for controlling the gain of at least one of the plurality of amplifiers. In a focus control method for an information recording / reproducing apparatus, a step of starting servo control using a means for positioning in the focus direction as a closed loop,
A step of making the means for positioning with respect to the track an open loop, and as a result of the open loop, when the spot of the laser beam from the optical head moves in the direction traversing the track, the focus error signal or its function An information recording / reproducing apparatus comprising: a step of measuring a signal a plurality of times; and a step of optimizing a gain of the at least one amplifier by means of controlling the gain according to a result of the measurement. A focus control method is provided.

In another aspect of the present invention, in order to achieve the above object, a servo gain of a focus error signal obtained from an output signal of a plurality of divided sensors for receiving reflected light of a laser beam from a disk is controlled. Means for optimizing the servo loop gain according to the measurement result of the focus error signal.

That is, according to another aspect of the present invention, there is provided an optical disc recording / reproducing apparatus for recording information on a disc-shaped optical recording medium and / or reproducing the information recorded on the disc-shaped optical recording medium. And a means for driving the disk to rotate, an optical head for recording / reproducing data on / from the disk by a laser beam, a sensor divided into a plurality of parts for receiving reflected light of the laser beam from the disk, A tracking error signal is generated and fed back by calculating a plurality of output signals of the sensor, and means for positioning the optical head with respect to the track of the disk, and a focus error signal is generated by calculating a plurality of output signals of the sensor. At the same time, the focus error signal generating means for controlling the servo loop gain upon the feedback thereof and the servo loop A means for positioning the optical head in the focus direction by feeding back the focus error signal whose gain is controlled, and recording and reproducing information by exchanging signals with the optical head and modulating and demodulating the recording and reproducing signal. In a focus control method for an information recording / reproducing apparatus having means, a step of starting servo control with the means for positioning in the focus direction being a closed loop, and a step of making the means for positioning with respect to the track an open loop. As a result of becoming an open loop, when the spot of the laser beam from the optical head moves in the direction traversing the track, measuring the focus error signal or a function signal thereof a plurality of times, and depending on the result of the measurement. By the focus error signal generating means And a step of optimizing the serial servo loop gain, focus control method in an information recording / reproducing apparatus characterized in that it has, is provided.

[0011]

According to the focus control method of the present invention, even if the optical spot deviates in the jitter direction due to the change with time of the optical head,
In particular, it is possible to effectively prevent the operation of the focus servo control system from becoming unstable when the optical head moves in the radial direction of the disk such as at the time of kicking or seeking.
Since the focus servo can be executed stably, there is no big problem such as the inability to read important data afterwards due to the unstable focus servo control, and the playability is increased and the commercial value is increased.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 is a block diagram showing an MD recording / reproducing apparatus as an example of an optical disk recording / reproducing apparatus for realizing the focus control method of the present invention. FIG. 3 is a circuit diagram showing a main part of the preamplifier shown in FIG. Further, FIG. 1 is a flowchart showing an example (first embodiment) of a processing procedure of a portion related to focus control during operation of the microcomputer 11 in FIG.

In FIG. 2, a magneto-optical disk (also referred to as a disk or an optical disk) 1 known as an MD (mini disk) has tracks formed in a spiral shape from the inner circumference to the outer circumference. By applying a laser beam spot to this track, bibliographic information, audio information, and video information in a predetermined format are optically recorded and reproduced. The disc 1 is servo-controlled by the servo circuit of the block 10 on the basis of the signal read and reproduced by the optical pickup 2.
It is rotated at CLV (constant linear velocity) by the spindle motor 3 and the motor driver / tracking focus control circuit 4. The optical pickup 2 has a superposing device 5 and operates integrally with the magnetic field modulation head 7. The optical pickup 2 and the magnetic field modulation head 7 constitute an optical head. The optical head can be moved in the radial direction of the disk 1 by a traverse motor 6.

The optical pickup 2 also has a laser diode LD for emitting a laser beam to the disc 1, and outputs signals RF1 and RF2 for reproducing the optical information recorded on the disc 1 based on the reflected light. Or the astigmatism 4-division focus error signal detection signal A
.About.D and two tracking error signal detection signals E and F of the 3-beam method are output. These signals RF1, RF
2, A to F are amplified by the head amplifier 8 and output to the preamplifier 9 that operates as a detection / adjustment unit. Further, a signal for driving the laser diode LD in the optical pickup 2 is applied from the preamplifier 9 to the head amplifier 8.

FIG. 5 shows the sensor portion AB of the optical pickup 2.
CDEFIJ is shown as a quadrangle, and a state in which a light spot is incident on them is shown as a circle. The direction indicated by arrow Y is the longitudinal direction of the track, and the direction indicated by arrow X is the radial direction of the disc perpendicular to the longitudinal direction of the track. The signals A to F are output from each of the sensor portions ABCDEF, and the signals RF1 and RF2 obtained by reproducing optical information are output from the sensor portion IJ. FIG.
FIG. 6 is a schematic diagram showing a positional deviation of a reflected light spot on a four-division sensor ABCD. The traveling direction of the truck in the figure is the left direction as indicated by the arrow. In FIG. 6, a first example on the left shows a case where the spot is displaced in the traveling direction of the truck, and a second example on the right side shows a case where the spot is displaced in the direction of the sensor D.

The preamplifier 9 is a memory controller / EF
The reproduced EFM signal, ADIP signal, focus error signal FEO, tracking error signal TEO, etc. are output to the M modulation / demodulation / error correction / ADIP (address implementation groove) / servo circuit block 10. The block 10 servo circuit is, for example, a DS
It is composed of P (digital signal processor).
The 4 MB DRAM 13 temporarily stores data when recording and reproducing data is compressed and expanded, and writing and reading are controlled by the memory controller of the block 10 instructed by the microcomputer 11. .

A memory controller / EFM modulation / demodulation / error correction / ADIP / servo circuit block 10 encodes recording data at the time of recording, modulates it into an EFM signal, and outputs it to the magnetic field modulation head 7 via a driver 7a. The servo circuit of the block 10 also demodulates the EFM signal from the preamplifier 9 at the time of reproduction to perform error correction decoding, and the optical pickup 2 with respect to the track of the disc 1 based on the focus error signal FEO and the tracking error signal TEO. Control is performed via the motor driver / tracking / focus control circuit 4 so as to perform tracking and focusing. The motor driver / tracking / focus control circuit 4 constitutes, together with the preamplifier 9 and the block 10, servo control means as two positioning means in tracking and focus control. In addition, the optical pickup 2 is activated when the microcomputer 11 is turned on or when the disc is inserted.
As described later, the offset and balance of the tracking error signal TEO are adjusted, and the vicinity of the innermost circumference of the disk 1 (TOC: Table Of Contents and UTOC: User Ta
ble Of Contents) and read the necessary ID information. The D / A converter / A / D converter block 14 A / D-converts the analog recording signal to give it to the block 10, and D / A-converts the reproduced signal from the block 10 to output it as an analog signal to the outside. Is. FIG. 4 is a waveform diagram showing various aspects of the focus error signal FEO and the tracking error signal TEO, the contents of which will be described later.

The microcomputer 11 includes an A / D converter 11a for taking in various signals A to F, FEO, TEO, etc. from the preamplifier 9 and a laser diode LD in the optical pickup 2.
, A PWM section 11b for controlling the output power of the laser diode LD, and the like, and a RAM1 for a work area, etc.
1c, a ROM 11d for programs and the like, a CPU 11e for performing control as described later, and the like, and these circuits 11a to 11e are connected via a bus 11f.
Further, the RAM 11c has an area for storing a balance of the focus error signal or an offset adjustment value for the CPU 11e to perform the adjustment described later. PWM
The PWM signal from the unit 11b is a low pass filter (LP
It is converted into a DC voltage by F) 12 and applied to the laser power control circuit (LPC) 22 shown in FIG. 2, and then the laser diode LD in the optical pickup 2 is driven via the head amplifier 8. Further, the microcomputer 11 is connected with an input means 16 and a display means 18, respectively, and receives an instruction from a user and displays a recording / reproducing state, a control state and the like.

In the optical disc recording / reproducing apparatus to which the present invention is applied, the tracking servo control and the focus servo control are performed by the servo control means composed of the blocks 4 and 10 and the preamplifier 9. As described above, the focus search is performed when the power is turned on, the disk is exchanged, and the focus servo control is changed from the on state to the off state due to a large impact. Before the description, the contents of servo control will be described. First, the configuration of the preamplifier 9 will be described in detail with reference to FIG. The RF signals RF1 and RF2 input from the optical pickup 2 via the head amplifier 8 are information reproduction signal output circuit 21.
Is output to the memory controller / EFM modulation / demodulation / error correction / ADIP circuit 10 as an EFM signal or an ADIP signal. Further, in order to adjust the focus balance, the envelope signal EFMENV of the EFM signal is detected by the EFMENV detection circuit 21a and output to the A / D converter 11a in the microcomputer 11.

The output signals A to D of the four-division sensor ABCD for focus error signal detection shown in FIG. 5 are amplified by amplifiers 32A to 32D and then applied to a focus balance differential amplifier 23F as shown in FIG. Signal FE =
A + C-B-D is calculated. The variable resistance means 24F for focus balance is connected to the + terminal of the differential amplifier 23F.
The focus balance voltage determined by 1, 24F2 is applied. Therefore, the differential amplifier 23F outputs the focus error signal FE of {α (A + C) −BD−} (α is a coefficient corresponding to the focus balance adjustment amount). In addition, the focus offset differential amplifier 27F
By applying an offset voltage to (A + C)-
A focus error signal FE for changing the positioning position on the error signal of (B + D) + β is output. Further, the signals A to D are given to the adder 20, and the sum signal ASO is produced and sent to the servo circuit of the block 10. In addition, 4
In the present embodiment, of the two amplifiers 24A to 24D, the amplification degree, that is, the gain of the two amplifiers 32A and 32D is fixed, and the gains of the other two amplifiers 32B and 32C are variable. That is, the gains of the amplifiers 32B and 32C are controlled by the control signal GC applied to the amplifiers 32B and 32C from the microcomputer 11 via the microcomputer data I / F 36.
(B), controlled by GC (C).

Here, focus balance variable resistance means 24F1 and 24F2, a focus gain variable resistance means 26F, a focus offset variable resistance means 28F, and a tracking balance variable resistance means 2 which will be described later.
4T1, 24T2, tracking gain variable resistance means 26T, and tracking offset variable resistance means 28
Each T is composed of a plurality of stages of resistance ladders and analog switches. Further, two variable resistance values for the focus balance variable resistance means 24F1 and 24F2, and two for the tracking balance variable resistance means 24T1 and 24T2.
The two variable resistance values are controlled in conjunction.

These variable resistance means 24F, 26F, 2
Each of the 8F, 24T, 26T, and 28T analog switch groups corresponds to a register (RAM 11) of the microcomputer 11 shown in FIG.
Focus balance signal FBAL, focus gain signal FG, focus offset signal FOFS, tracking balance signal TB according to the data set in c)
The AL, the tracking gain signal TG, and the tracking offset signal TOFS are given from the microcomputer data I / F 36 to selectively turn them on or off. Therefore, the resistance value changes in steps, and the balance (BAL) of the focus (F) signal, the gain (G) and the offset (OFS), and the balance (BA) of the tracking (T) signal.
L), gain (G) and offset (OFS) can be adjusted.

The output voltage FE of the differential amplifier 23F is amplified based on the focus gain signal FG by the focus gain amplifier 25F and the variable resistance means 26F, and then by the focus offset differential amplifier 27F and the variable resistance means 28F. Focus offset signal FOF
The focus offset is adjusted based on S. This signal is used as the focus error signal FEO in the servo circuit 1
0 and is output to the A / D converter 11a in the microcomputer 11.

The polarities of the output signals E and F of the two-divided sensors E and F for detecting the tracking error signal from the optical pickup 2 are the polarity selection signal TE from the microcomputer 11.
The polarity can be switched by the polarity switching circuit 29 based on SEL. The output signals E and F of the polarity switching circuit 29 are applied to the tracking balance differential amplifier 23T and the differential amplifier 23T and the variable resistance means 24T1 and 24T2.
Therefore, when the signal TESEL is straight based on the tracking balance signal TBAL, the tracking error signal (βF-E) (β is the tracking balance adjustment amount) is obtained, and when the signal TESEL is cross, the tracking error signal (βE-F) is obtained. Is generated.

The output voltage is amplified by the tracking gain amplifier 25T and the variable resistance means 26T based on the tracking gain signal TG, and then the tracking offset differential amplifier 27T and the variable resistance means 28 are used.
The offset is adjusted by T based on the tracking offset signal TOFS. This signal is output as a tracking error signal TEO to the servo circuit 10 and the A / D converter 11a in the microcomputer 11. Also, in order to adjust the balance and offset of the tracking error signal TEO, the voltage H above the tracking error signal TEO is adjusted.
And the lower voltage L is held by the peak hold circuit 30 which operates as peak measuring means. The peak hold circuit 30 can be reset by a reset signal from the microcomputer 11.

A specific example in the case of performing control using such a servo control system will be described. When the spot of the reflected light obtained by the optical pickup 2 is deviated from the center position in the traveling direction of the truck as shown in the first example on the left side of FIG. The track crossing signal leaks into A + C- (B + D) which is the basic component of the focus error signal FEO. In this embodiment, in such a case, the gains of the amplifiers 32B and 32C are slightly increased in order to amplify the voltages B and C. As a result, apparently the ABCD is balanced. That is, the above-mentioned balance can be obtained by changing the gain on at least one side of the sensor divided in the traveling direction of the truck.

In the first embodiment of the focus control method in the optical disk recording / reproducing apparatus of the present invention, the control shown in FIG. 1 is performed. This control is mainly performed by the CPU 11e in the microcomputer 11. In step S1, the data indicated by the focus error signal FEO and other signals and the status of the recording / reproducing apparatus (operation mode)
Take in. In step S2, it is determined whether or not the focus search is necessary by detecting the insertion of the disk or the like, and if it is necessary, the gains of the amplifiers 32B and 32C are set to the initial values in step S3, and then the focus and tracking offsets are adjusted. . That is, the focus error signal FEO
Further, the tracking error signal TEO is compared with the respective reference voltages, and the focus offset signal FOFS and the tracking offset signal TOFS are produced so that the difference between them becomes 0, and the feedback control is performed.

Next, in step S5, a current is gradually applied to a focus coil (not shown) of the optical pickup 2 to raise the optical pickup 2 and move it toward the disk. While the optical pickup 2 is moving up, the voltage value of the focus error signal FEO is measured, and the so-called S curve is measured. In the S curve, if the upper side of the reference voltage is + and the lower side is −, the peak value on the + side and the peak value on the − side are fetched and stored. Next, in step S5, the focus servo control is turned on (the feedback loop is closed loop). To ensure the operation, the servo signal is turned on after confirming that the sum signal ASO given from the preamplifier 9 exceeds a predetermined threshold value Asa and recognizing that the disk 1 is present. Can make decisions.

Next, in step S6, the spindle motor 3
And the tracking servo control is turned on in the next step S7. Then, in step S8, the servo control of the spindle motor 3 is turned on to perform CLV control. Then, in step S9, the traverse motor 6 is turned on to move the optical pickup 2 to a predetermined position for adjustment (for example, the center position of the area in which TOC information is recorded).
In subsequent step S10, the tracking servo control is turned off (open loop). When the tracking servo control is turned off, the light spot of the optical pickup crosses the track due to the eccentricity of the disc. Therefore, the voltage of the focus error signal FEO fluctuates, so the maximum value and the minimum value during that time are measured in step S11, and the difference is calculated and stored.

A conversion table for obtaining the set gain of the amplifier 32B from the difference between the maximum value and the minimum value is stored in advance in the ROM 11d. The corresponding gain is read in step S12 to adjust the gain of the amplifier 32B. Set. In the next step S13, the focus error signal FE
By determining whether the difference between the maximum value and the minimum value of O is minimized, and repeating steps S11, S12, and S13,
When the difference is minimum, steps S14, S15, S16
Move to. Steps S14, S15, and S16 are the same adjustments as steps S11, S12, and 13 for the amplifier 32C. If YES in step S16, the tracking servo control is turned on (closed loop) in step S17, and the process proceeds to a main routine S30 that executes recording / reproduction, track jump, and the like.

Control signals GC (B) and GC (C) for adjusting / setting the gains of the amplifiers 32B and 32C are supplied from the microcomputer 11 to the gain control terminals of these amplifiers 32B and 32C via the microcomputer data I / F 36. Given.
In the flow of FIG. 1, the gain adjustment of the amplifiers 32B and 32C is sequentially performed, but when the moving direction of the light spot is limited to the traveling direction of the track, the gain adjustment of both amplifiers can be performed simultaneously.

The waveform in the upper part of FIG. 4 shows that the focus servo control is in the ON state, the focus error signal FEO does not fluctuate, and the tracking servo control is in the ON state from the OFF state. Is. The middle waveform shows a state in which the groove crossing signal due to the track cross is mixed in the focus error signal FEO and is in phase with the tracking error signal TEO. The lower part shows the focus error signal FEO obtained after the gain adjustment according to this embodiment in relation to the tracking error signal TEO, and the middle part of the focus error signal FEO is shown.
It can be seen that the amplitude is attenuated by about half as compared with.

When the light spot is deviated in the direction of the sensor D as in the second example of FIG. 6, the balance between the sensors A and C is omitted and the gain of only the amplifier 32B corresponding to the sensor B is adjusted. May be. As can be seen from the two examples in FIG. 6, the detection of the groove crossing signal is determined by the area and the optical power of the light receiving portion of each sensor, while the gain adjustment does not change the area apparently. Correction is performed. Therefore, although the groove crossing signal mixed in the focus error signal FEO cannot be completely removed, it can be at least halved as described above.

Next, a second embodiment of the present invention will be described with reference to the flowchart of FIG. In FIG. 7 and the following flow charts, the steps with the same step numbers are the same as the other flow charts, and therefore the differences will be mainly described.
After the measurement and calculation are completed in step S11, it is determined whether or not there is a track cross in step S20 using the calculation result. When the difference that is the calculation result is smaller than the predetermined value, there is no crossing of the track, so to forcefully cross it,
In step S21, the optical pickup 2 is vibrated (vibrated). The subsequent gain adjustment is basically the same as that in FIG. 1, but if necessary, steps S14 and S15 are performed.
It is also possible to insert a step for vibration similar to steps S20 and S21 in between.

Next, a third embodiment of the present invention will be described with reference to the flowchart of FIG. The third embodiment differs from the second embodiment of FIG. 7 only in the following points. After step S16, step S22 is provided to determine whether or not the device is at the time of recording / reproducing. At the time of recording / reproducing, the gains of the amplifiers 32B and 32C are returned to the initial setting values in step S23. In other modes, the gain set in steps S12 and S15 is used. In this embodiment, steps S12 and S
The gains of the amplifiers 32B and 32C set in 15 are used only at the time of track crossing. That is, during recording / reproduction with the tracking servo control turned on, the gain adjustment is not performed for the sensor output voltages A, B, C, D by the initial setting value, that is, the difference between the maximum value and the minimum value of the focus error signal FEO. , The value is used as it is, and the adjusted gain is set only at the time of kicking or seeking which is tracking off. This is because the adjusted gain stabilizes the focus servo control when kicking or seeking, but when recording / reproducing, the S curve during focus control is electrically corrected, so the dynamic range of servo control is reduced. Because there is
In the third embodiment, the amplifier 32 is operated at step SS23.
Although the gains of B and 32C are returned to the initial setting values, other setting values may be read from the memory or a value calculated using a measured value may be used as the setting value.

Next, a fourth embodiment of the present invention will be described with reference to the flow chart of FIG. 9 and FIGS.
In the fourth embodiment and the fifth embodiment which will be described with reference to the flow chart of FIG. 10, a servo circuit for focus servo control in the memory controller / EFM modulation / demodulation / error correction / ADIP / servo circuit block 10 shown in FIG. 2 is shown. The configuration shown in 13 is used. Note that FIG.
The preamplifier 9 can be used in this embodiment as it is, but the gains of the amplifiers 32B and 32C do not need to be variable, and therefore the gain control signals GC (B) and G (G).
C (C) is unnecessary. As the servo circuit in the block 10, there is a servo circuit for tracking servo control, but the illustration is omitted here. The servo circuit 40 includes adders 46 and 56, delay circuits (unit delay elements) 44 and 48,
It has amplifiers 50, 52, 54 and 58.

The flowchart of FIG. 9 differs from that of FIG. 1 in the following points. That is, unlike step S3, step S3A does not set the gain of the amplifier (or a fixed gain type amplifier can be used). Further, step S12 and subsequent steps in FIG. 1 are replaced with a series of steps from step S24 and subsequent steps. In step S24, it is determined whether the difference between the maximum value and the minimum value of the voltage of the focus error signal FEO is equal to or more than a predetermined value. If the difference is equal to or more than the predetermined value, it is determined that the groove leak component is large and the value corresponds to that value. The gain value of the servo system is read from the ROM 11d in step S25, and this gain is set in the servo control circuit 40. In addition, ROM
A conversion table for obtaining a set gain from the difference between the maximum value and the minimum value is stored in advance in 11d.

Here, the contents of setting the gain value of the servo system are as follows.
Adjust one or more of G2, G3, G4. G1 here
Is the gain of the integral term, G2 is the gain of the proportional term, G3 is the gain of the derivative term, and G4 is the overall gain. There are various methods for adjusting the gain, such as a method of lowering the total gain G4, a method of lowering only the gain G1 of the integral term, and a method of increasing any gain depending on the frequency of the disturbance and the configuration of the servo circuit.

In the next step S17, the tracking servo control is turned on, and in step S22, it is determined whether or not recording / reproducing (including standby). If YES, the servo system gain is returned to the normal value in step S27. On the other hand, if NO, the gain obtained in step S25, that is, the lowered gain in this embodiment is set in step S29. That is, the loop gain setting of the focus servo control system is a countermeasure against the groove leakage component when the tracking servo control is in the off state, and is a normal value during recording / reproduction, that is, when the tracking servo control is in the on state. Since it is desirable to set to, steps S10 and S1 in FIG.
On / off of the tracking servo control is controlled by 7, and the loop gain (servo constant) is switched at the time when the state is switched. This switching stabilizes the focus servo control both during steady state and during track crossing. Although the switching of the loop gain is performed when the tracking servo control is turned on / off, the third loop gain (servo constant) may be used in the middle of the transition between the modes. After completion of step S27 or step S29, the process proceeds to the main routine S30, and then step S
Return to 22.

Next, a fifth embodiment of the present invention will be described. The fifth embodiment is a modification of the contents of step S11 of FIG. 9, and is otherwise the same as FIG. FIG. 12 shows the focus error signal FEO and the tracking error signal TEO.
FIG. 6 is a waveform diagram showing the relationship of changes in the tracking error signal TE in step S11 (not shown).
When the rise (increase) of O is detected, the focus error signal FEO at the end of the rise is stored as the maximum value, then the fall (decrease) of the tracking error signal TEO is detected, and the fall is completed. Focus error signal FE
Store O as the minimum value. These two signals are detected by operating the changeover switch 42 shown in FIG. 13 with a control signal provided from the microcomputer 11 via the microcomputer data I / F 36. The other steps are shown in FIG.
Therefore, the description is omitted. In this way, by measuring the focus error signal FEO and the tracking error signal TEO, confirming that they are in phase, and then using the measured value of the focus error signal FEO as a correct value, the influence of scratches on the disk It is possible to prevent the problem that the proper measurement is not performed due to the impact from the outside or the outside. The confirmation of the coincidence of the phases of the two signals can be applied to the above-described first to fourth embodiments and the sixth embodiment described later.

Next, a sixth embodiment of the present invention will be described with reference to the flowchart of FIG. 10 differs from FIG. 9 in the following points. That is, after the measurement and calculation are completed in step S11, it is determined whether or not there is a track cross in step S20 using the calculation result. When the difference as the calculation result is smaller than the predetermined value, the track is not traversed. Therefore, in order to forcefully traverse, the optical pickup 2 is vibrated (vibrated) in step S21. The subsequent loop gain adjustment of the servo system is basically the same as that shown in FIG. 9, and the contents of the fifth embodiment described above can be added as a variation. Step S2 in the fourth to sixth embodiments
In 7, the loop gain of the servo system is returned to the normal value, but in addition to that, other set values are read from the memory,
A value calculated by using a measured value or the like can be used as the set value.

In each of the above-mentioned embodiments, the deviation of the light spot is often caused by a change over time due to the structural factor of the optical pickup 2. Therefore, the moving direction is predetermined, the moving direction is the elapsed time, or the feedback from the temperature sensor is made. When it can be predicted from the information, the gain adjustment can be performed by a simpler method. In each of the above embodiments, the focus error signal F
The EO is measured and the gain is controlled.
A function signal of the focus error signal FEO such as the sum signal ASO of the split sensor may be used instead. Further, as a method of detecting the focus error signal FEO, the same effect can be obtained by using a method other than astigmatism.

[0043]

As described above, according to the present invention, even if the spot of the reflected light incident on the optical head (optical pickup) is shifted in the jitter direction, the optical head is disc driven, especially at the time of kick or seek. It is possible to suppress adverse effects due to the mixture of the groove leakage component when moving in the radial direction, and to stably perform the focus servo control. In addition, the desired focus servo control can be performed by vibrating the optical pickup as necessary, and by confirming the phase match with the tracking error signal when measuring the focus error signal, shock etc. The negative effects of can be ruled out.

[Brief description of the drawings]

FIG. 1 is a flowchart showing a first embodiment of a focus control method in an optical disc recording / reproducing apparatus of the present invention.

FIG. 2 is a block diagram showing an MD recording / reproducing device as an example of an optical disc recording / reproducing device for realizing the focus control method of the present invention.

FIG. 3 is a block diagram showing a configuration of a preamplifier in FIG. 2 used in the first to third embodiments of the focus control method of the present invention.

FIG. 4 is a waveform diagram showing various aspects of a focus error signal FEO and a tracking error signal TEO.

5 is a plan view showing the relationship between the arrangement of optical sensors and the optical spots used in the optical disc recording / reproducing apparatus of FIG.

6A and 6B are plan views showing two examples of displacement of a light spot in a 4-division sensor portion in the optical sensor shown in FIG.

FIG. 7 is a flowchart showing a second embodiment of the focus control method in the optical disc recording / reproducing apparatus of the present invention.

FIG. 8 is a flowchart showing a third embodiment of the focus control method in the optical disc recording / reproducing apparatus of the present invention.

FIG. 9 is a flowchart showing a fourth embodiment of the focus control method in the optical disc recording / reproducing apparatus of the present invention.

FIG. 10 is a flowchart showing a sixth embodiment of the focus control method in the optical disc recording / reproducing apparatus of the present invention.

FIG. 11: 1 of a disc having a focus error signal FEO
It is a wave form diagram which shows the change during rotation.

FIG. 12 is a waveform diagram showing the relationship between the focus error signal FEO and the tracking error signal TEO for explaining the fifth embodiment of the focus control method of the present invention.

FIG. 13 is a block diagram showing a partial configuration of the servo circuit in FIG. 3 used in the fourth to sixth embodiments of the focus control method of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 optical disk 2 optical pickup (which constitutes an optical head together with a magnetic field modulation head) 3 spindle motor (means for rotationally driving a disk) 4 motor driver / tracking focus control circuit (preamplifier 9 and block 10 constitute two positioning means) 7 magnetic field modulation head 7a driver 8 head amplifier 9 preamplifier 10 memory controller / EFM modulation / demodulation / error correction / ADIP (address implement groove) / servo circuit block (modulation demodulation means) 11 microcomputer (adjustment means) 13 DRAM 14 D / A Converter / A / D converter block 16 Input means 18 Display means 21 Information reproduction signal output circuit 21a EFMENV detection circuit 22 Laser power control circuit 29 Polarity switching circuit 30 Peak hold circuit 32A, 32B, 2C, 32D, 50,52,54,
58 amplifier 36 microcomputer data I / F 40 servo control circuit 44, 48 delay circuit (unit delay element) 46, 56 adder

Claims (6)

[Claims] 1. An optical disc recording / reproducing apparatus for recording information on a disc-shaped optical recording medium and / or reproducing the information recorded on the disc-shaped optical recording medium, comprising means for rotationally driving the disc. , An optical head for recording / reproducing data on / from the disk by a laser beam, a plurality of divided sensors for receiving reflected light of the laser beam from the disk, and amplifying each of a plurality of output signals of the sensor A plurality of amplifiers, a means for generating and feeding back a tracking error signal by calculating output signals of the plurality of amplifiers, and positioning the optical head with respect to the track of the disk; and a plurality of output signals of the plurality of amplifiers. Generate a focus error signal by calculation and feed it back,
Means for positioning the optical head in the focus direction,
An information recording / reproducing apparatus having a modulation / demodulation unit for recording / reproducing information by transmitting / receiving a signal to / from the optical head and modulating / demodulating a recording / reproducing signal, and a unit for controlling a gain of at least one of the plurality of amplifiers. In the focus control method according to, the step of starting servo control using the means for positioning in the focus direction as a closed loop, the step of opening the means for positioning with respect to the track as an open loop, and When the spot of the laser beam from the head moves in the direction traversing the track, a step of measuring the focus error signal or a function signal thereof a plurality of times, and at least the means for controlling the gain according to the result of the measurement. Optimize the gain of one amplifier And a step, a focus control method in the information recording / reproducing apparatus characterized in that it comprises. 2. A step of determining whether or not the information recording / reproducing apparatus is in a recording / reproducing state, and changing the optimized gain when it is determined to be in the recording / reproducing state,
The focus control method in the information recording / reproducing apparatus according to claim 1, further comprising a step of setting a means for positioning with respect to the track as a closed loop loop. 3. An optical disc recording / reproducing apparatus for recording information on a disc-shaped optical recording medium and / or reproducing information recorded on the disc-shaped optical recording medium, comprising means for rotationally driving the disc. , An optical head for recording / reproducing data on / from the disc by a laser beam, a sensor divided into a plurality of parts for receiving reflected light of the laser beam from the disc, and tracking by calculating a plurality of output signals of the sensor An error signal is generated and fed back, and a focus error signal is generated by a means for positioning the optical head with respect to the track of the disk and a calculation of a plurality of output signals of the sensor. Focus error signal generation means for controlling the focus error signal, and the focus error signal with the servo loop gain controlled. Information recording / reproducing means for returning an error signal to position the optical head in the focus direction and a modulation / demodulation means for recording / reproducing information by exchanging a signal with the optical head and for modulating / demodulating the recording / reproducing signal. In the focus control method for a reproducing apparatus, a step of starting servo control with the means for positioning in the focus direction being a closed loop, a step of making the means for positioning with respect to the track an open loop, and the result of being an open loop, When the spot of the laser beam from the optical head moves in the direction traversing the track, a step of measuring the focus error signal or a function signal thereof a plurality of times, and the focus error signal generating means according to the result of the measurement. Optimize the servo loop gain A focus control method in an information recording / reproducing apparatus, comprising: 4. A step of determining whether the information recording / reproducing apparatus is in a recording / reproducing state, and changing the optimized servo loop gain when it is determined that the information recording / reproducing apparatus is in a recording / reproducing state, 4. The focus control method in an information recording / reproducing apparatus according to claim 3, further comprising the step of making a means for positioning with respect to a track a closed loop. 5. A step of determining whether or not a spot of a laser beam from the optical head has moved in a direction traversing the track after the means for positioning with respect to the track is an open loop, and the optical head. When it is determined that the spot of the laser beam from is not moving in the direction crossing the track,
The focus control method for an information recording / reproducing apparatus according to claim 1, further comprising: vibrating the optical head so that a spot of the laser beam moves in a direction traversing a track. 6. The step of measuring the focus error signal or a function signal thereof a plurality of times comprises the step of measuring the tracking error signal or a function signal thereof a plurality of times, and the step of confirming that the phases of both are in agreement.
The focus control method in the information recording / reproducing apparatus according to claim 1, further comprising the step of using the focus error signal or a function signal thereof obtained when the phases match each other.