JP2002117555A - Optical disk reproducing device and optical disk recording device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical disk reproducing device and optical disk recording device capable of stably executing focus search and focus servo control even if S curves are large and asymmetric. SOLUTION: The device has a means of setting the balance between optical output signals prior to the computation of a sensor according to a balance quantity with respect to a focus error signal, a means for impressing an offset voltage according to the offset quantity to the focus error signal and a means for regulating the balance quantity and/or the offset quantity in order to detect the finest state of regenerative signals by moving an optical pickup in the focus direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
(Compact disc), DVD high density (digital video disc) MD (mini disc) and PC (phase change type)
The present invention relates to an optical disk reproducing device for reproducing information recorded on an optical disk such as a disk, and an optical disk recording device for recording information on the optical disk.

[0002]

2. Description of the Related Art Generally, in this type of information recording / reproducing apparatus, tracking control and focus control of an optical head are performed, and data is accurately written and read during recording and reproduction. 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 disk during recording (hereinafter referred to as laser power)
Is adjusted in multiple stages according to the wattage specified by the disk, and during playback, the laser power is varied in multiple stages for several types of disks (pre-mastered and MO) with different reflectivities, The gain of the tracking error signal and the gain of the focus error signal are switched in order to adjust the error, and the offset of these error signals is adjusted each time the switching is performed. At this time, it is necessary to accurately adjust the adjustment target such as the offset and balance of the tracking error signal and the focus error signal in consideration of the compatibility with other devices.

The servo control circuit of such an information recording / reproducing apparatus is configured as follows. The output signal of each of four sensors A, B, C, and D (see FIG. 5) divided into four parts by an astigmatism method in an optical head or an optical pickup included in the optical head is subjected to I / V conversion and amplified output. Generates a focus error signal basically represented by A + C-B-D. Further, a tracking error basically expressed by EF is generated from an output obtained by I / V converting and amplifying each output signal of the two sensors E and F of the three-beam method. These error signals are supplied to an A / D converter to be converted into digital signals, digital servo processing is performed by a servo control circuit, the output of which is output via a D / A converter, and a focus coil is output by a motor drive circuit. And the tracking coil is driven. In the calculation process of the focus error signal FEO, the balance adjustment between a plurality of sensor output signals and the signal level offset adjustment are performed.

[0004]

Here, the spot of the reflected light of the laser beam is directed perpendicularly to the optical axis (in the direction of jitter (the running direction of the disk)) with respect to the four-divided ABCD sensor that generates a focus error. If it deviates in the tracking direction (compositing direction of the tracking direction), the S curve obtained from the level change of the focus error signal during the focus search becomes asymmetric with respect to the reference voltage, and the servo control becomes unstable such that the servo pull-in does not succeed in the focus search. There was a problem.

If the spot of the reflected light of the laser beam deviates in the optical axis direction with respect to the detection sensor, the S curve obtained from the focus error signal is symmetric, but the best quality point of the reproduced signal on the S curve is A + C or B + D at the time of startup by automatic adjustment means to shift from the center
By changing either of the gains, or (A
By injecting an offset into the focus error signal of (+ C)-(B + D), the S-curve is offset, and the S-curve is forcibly asymmetric so as to center on the best quality point of the reproduced signal.

Further, since an offset voltage is generated in the ABCD sensor, amplifying circuit and optical system, there is an offset adjusting circuit which sets the offset voltage to 0 at the time of startup by an automatic adjusting means, and adjusts the offset voltage. However, if these are individually adjusted after startup, for example, if the influence on the focus error signal due to the above-described vertical spot deviation and the optical axis direction deviation is in the same direction, the S curve becomes largely asymmetric, and the reproduction is The signal has the best quality, but the focus servo control cannot be turned on normally (locked state), search cannot be performed, or servo control becomes unstable in subsequent operations. Had been a problem. In addition, important data could not be read because the servo control could not be turned on by focus search.

The present invention has been made in view of the above-mentioned conventional problems, and provides an optical disk reproducing apparatus and an optical disk recording apparatus capable of executing focus search and focus servo control stably even if the S curve becomes largely asymmetric. With the goal.

[0008]

In order to solve the above-mentioned problems, the present invention provides an optical disk reproducing apparatus and an optical disk recording apparatus having the following constitution. (1) An optical disk reproducing apparatus for reproducing information recorded on an optical disk, comprising: means for rotating and driving the optical disk; an optical pickup for reproducing data from the optical disk by a laser beam; A plurality of divided sensors for receiving the reflected light, a tracking error signal generated by calculating a plurality of output signals of the sensor and feedback, and an optical pickup for positioning the optical pickup in a track direction of the optical disc; A focus error signal is generated and returned by calculation of a plurality of output signals of the sensor, and the feedback is performed.A means for positioning the optical pickup in a focus direction, a demodulation means for reproducing information from the optical pickup and demodulating a reproduction signal, Before the calculation of the sensor with respect to the focus error signal Balance setting means for setting a balance between a plurality of output signals according to a balance amount, offset setting means for applying an offset voltage to the focus error signal according to an offset amount, and means for positioning in the focus direction. An optical disk reproducing apparatus comprising: an adjusting unit that adjusts the balance amount and / or the offset amount to move the optical pickup in a focus direction and detect the best state of the reproduction signal. (2) An optical disk recording apparatus for recording information on an optical disk, comprising: means for rotating and driving the optical disk, an optical head for recording data on the optical disk by a laser beam, and reflection of the laser beam from the optical disk A plurality of divided sensors for receiving light, a means for generating a tracking error signal by calculating a plurality of output signals of the sensor and feeding it back, and positioning the optical head in a track direction of the optical disc; Means for generating and feeding back a focus error signal by calculation of a plurality of output signals, and a means for positioning the optical head in a focus direction, and recording information by transmitting and receiving signals to and from the optical head and modulating a recording signal. Means,
Balance setting means for setting the balance between the plurality of output signals before the calculation of the sensor according to the balance amount with respect to the focus error signal and / or applying an offset voltage to the focus error signal according to the offset amount. Offset setting means, adjustment means responsive to the focus direction positioning means, measuring characteristics of the focus error signal to adjust the balance amount and / or the offset amount, and positioning means in the focus direction. On the other hand, in order to detect the best state of the reproduction signal by moving the optical head in the focus direction, an adjusting means for adjusting the balance amount or the offset amount, and when the recording or reproduction state, the reproduction signal of the reproduction signal. Setting means for setting the balance or offset in the best state; Optical disk recording apparatus characterized by having setting means for setting the recording or reproducing state different balance amount or offset amount when.

[0009]

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 one embodiment of the present invention. FIG. 3 is a circuit diagram showing a main part of the preamplifier in FIG. 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 (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 a spirally formed track from the inner periphery to the outer periphery. By giving a laser beam spot to this track, bibliographic information, audio information, and video information in a predetermined format are optically recorded and reproduced. This disk 1 is servo-controlled by a servo circuit of a block 10 based on a signal read and reproduced by the optical pickup 2, and
The spindle motor 3 and the motor driver / tracking / focus control circuit 4 rotate at CLV (constant linear velocity). The optical pickup 2 has a superimposer 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 the traverse motor 6.

The optical pickup 2 also has a laser diode LD for emitting a laser beam to the disk 1, and outputs signals RF1 and RF2 for reproducing optical information recorded on the disk 1 based on the reflected light. Or a focus error signal detection signal A divided into four by the astigmatism method
.. D and two tracking error signal detection signals E and F of the three-beam method. These signals RF1, RF
2. AF are amplified by a head amplifier 8 and output to a preamplifier 9 which operates as a detecting / adjusting means. 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 a sensor part AB of the optical pickup 2.
CDEFIJs are shown as rectangles, and the light spots incident on them are shown as circles. 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 disk perpendicular to the longitudinal direction of the track. The signals A to F are output from each of the sensor parts ABCDEF, and the signals RF1 and RF2 obtained by reproducing optical information are output from the sensor part IJ. FIG.
FIG. 4 is a schematic diagram showing a positional shift of a reflected light spot on the four-divided sensor ABCD. In the figure, the left and right parallel strips indicate the portion between tracks, and the middle white portion is the track. FIG. 7 to be described later is a waveform diagram showing a temporal change of a signal FE obtained by processing an output signal of the four-divided sensor during a focus search.

The preamplifier 9 is a memory controller / EF
A reproduced EFM signal, an ADIP signal, a focus error signal FEO, a tracking error signal TEO, and the like are output to the M modulation / demodulation / error correction / ADIP (address implement groove) / servo circuit block 10. The servo circuit of the block 10 is, for example, DS
P (digital signal processor).
The 4 MB DRAM 13 temporarily stores data when compressing and decompressing data at the time of recording and reproduction. Writing and reading are controlled by the memory controller of the block 10 which receives an instruction from the microcomputer 11. .

The memory controller / EFM modulation / demodulation / error correction / ADIP / servo circuit block 10 encodes the recording data at the time of recording, modulates the data into an EFM signal, and outputs it to the magnetic field modulation head 7 via the driver 7a. At the time of reproduction, the servo circuit of the block 10 also demodulates the EFM signal from the preamplifier 9 to perform error correction decoding, and based on the focus error signal FEO and the tracking error signal TEO, the optical pick-up 2 Control is performed via the motor driver / tracking / focus control circuit 4 so that tracking and focusing are performed. The motor driver / tracking / focus control circuit 4 together with the preamplifier 9 and the block 10 constitute a servo control means as two positioning means in tracking and focus control. Also, when the microcomputer 11 is turned on or when a disk is inserted, the optical pickup 2 is activated.
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 out the necessary ID information. A D / A converter / A / D converter block 14 A / D converts an analog recording signal and applies it to a block 10, and D / A converts a reproduction signal from the block 10 and outputs the analog signal to the outside. It is.

The microcomputer 11 includes an A / D converter 11a for receiving various signals A to F, FEO, TEO, and the like from the preamplifier 9, and a laser diode LD in the optical pickup 2.
For controlling the output power of the laser diode LD by driving the device with a signal corresponding to, for example, a 12-bit PWM signal, and a RAM 1 for a work area or the like.
1c, a ROM 11d for programs and the like, a CPU 11e for performing control as described below, and the like, and these circuits 11a to 11e are connected via a bus 11f.
The RAM 11c has an area for storing a balance or offset adjustment value of the focus error signal so that the CPU 11e performs an adjustment described later. PWM
The PWM signal from the unit 11b is a low-pass filter (LP
F) The DC voltage is converted into a DC voltage by 12 and applied to a 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. The input means 16 and the display means 18 are connected to the microcomputer 11, respectively, and receive instructions from the user and display a recording / reproducing state, a control state, and the like.

In an optical disk recording / reproducing apparatus which is a disk apparatus having one or both of an optical disk recording function and an optical disk reproducing function, tracking servo control and focus servo control are performed by servo control means including blocks 4, 10 and a preamplifier 9. However, when the power is turned on, the disk is replaced,
Focus search is performed when the focus servo control is turned off from the on state due to a large shock. Before the description, the contents of the 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 converted into an EFM signal, an ADIP signal, and the like via an information reproduction signal output circuit 21 as a memory controller / EFM modulation / demodulation / error correction / A
Output to the DIP circuit 10. Also, an envelope signal EF of the EFM signal is used to adjust the focus balance.
The MENV 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-divided sensor ABCD for detecting a focus error signal in FIG. 5 are applied to a focus balance differential amplifier 23F, and a signal FE = A
+ CBD is calculated. + Of this differential amplifier 23F
The terminal has variable resistance means 24F1 for focus balance,
The focus balance voltage determined by 24F2 is applied. Therefore, the differential amplifier 23F has a ｛α
A focus error signal FE of (A + C) −BD−α (α is a coefficient corresponding to a focus balance adjustment amount) is output. By applying an offset voltage to the focus offset differential amplifier 27F, (A + D) − (B
The focus error signal FE for changing the positioning position on the error signal of + D) + β is output. Signals A to
D is supplied to the adder 20 to generate a sum signal ASO, which is sent to the servo circuit of the block 10.

Here, variable resistance means 24F1 and 24F2 for focus balance, variable resistance means 26F for focus gain and variable resistance means 28F for focus offset, and variable resistance means 2 for tracking balance described later.
4T1, 24T2, tracking gain variable resistance means 26T, and tracking offset variable resistance means 28
T is composed of a plurality of stages of resistance ladders and analog switches. Further, two variable resistance values of the focus balance variable resistance means 24F1 and 24F2, and two variable resistance values of 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
The analog switch groups of 8F, 24T, 26T, and 28T correspond to the registers (RAM 11
Focus balance signal FBAL, focus gain signal FG, focus offset signal FOFS, tracking balance signal TB according to the data set in c)
AL, tracking gain signal TG, and tracking offset signal TOFS are selectively turned on or off by being supplied from microcomputer data I / F 36. Therefore, the resistance value changes stepwise, and the balance (BAL) of the focus (F) signal, the gain (G) and the offset (OFS), and the balance of the tracking (T) signal (BA)
L), gain (G) and offset (OFS) can be adjusted.

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

The polarity 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 is determined by 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 a tracking balance differential amplifier 23T, and the differential amplifier 23T and the variable resistance means 24T1 and 24T2.
When the signal TESEL is straight based on the tracking balance signal TBAL, the tracking error signal (βFE) (β is the tracking balance adjustment amount), and when the signal TESEL is cross, the tracking error signal (βEF) Is generated.

This output voltage is amplified by a tracking gain amplifier 25T and a variable resistance means 26T based on the tracking gain signal TG, and then a tracking offset differential amplifier 27T and a variable resistance means 28
T adjusts the offset based on the tracking offset signal TOFS. This signal is output to the servo circuit 10 and the A / D converter 11a in the microcomputer 11 as a tracking error signal TEO. 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 a peak hold circuit 30 operating 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 where control using such a servo control system is performed will be described. When the spot of the reflected light obtained by the optical pickup 2 deviates from the center position in the direction A of the XY synthesis direction, the following occurs. At the spot position indicated by the solid line as in the example shown in FIG. 6, that is, in the normal state, when the optical pickup 2 gradually approaches the disc 1 during the focus search, 4-
The signal FE changes like 1. However, as shown by the dotted line in FIG.
-2, output voltages A and D, B and C of the four-split sensor
Are shifted by A + C- (B + D), and the A + C side becomes larger.

In order to make the best point of the RF signal detected by the sensor IJ be the maximum point of the amplitude of the RF signal or the minimum point of the jitter, if the point is deviated from the maximum point as shown in 4-2, In this case, the gain on the B + D side (for example, 4 bits) is set such that the best point is the intersection with the reference voltage Ref of the S-curve while measuring the amplitude by the EFMENV detection circuit 21a which obtains the amplitude of the EFM signal of the RF signal in the FBAL. At 16
(Variable in steps). Thereby, the waveform becomes close to the waveform of 4-1 as shown in 4-3. The initial state is 4-4.
In the above example, since the maximum point of the amplitude of the RF signal is on the B + D side, by adjusting the gain on the B + D side to increase, the adjustment becomes as shown by 4-5. In this state, since the S-curve hardly extends to the B + D side (downward), servo control is turned on, and recording and reproduction in a state where disturbance is small in a steady state is possible, but in the focus search operation, S-curve is not used.
Servo control can hardly be normally turned on because the pull-in range below the curve is small and the slope is small (even if it is a closed loop, it will not be locked or will deviate immediately).

In the first example of the focus control method in the optical disk recording / reproducing apparatus, the control shown in FIG. 1 is performed to solve the above problem. This control is mainly performed by the CPU 11e in the microcomputer 11. Step S
In step 1, the data indicated by the focus error signal FEO and other signals and the status (operation mode) of the recording / reproducing apparatus are fetched. It is determined in step S2 whether or not a focus search is necessary by detecting insertion of a disc or the like, and if necessary, an offset adjustment between focus and tracking is performed in step S3. In other words, the focus error signal FEO and the tracking error signal TEO are compared with the respective reference voltages, and the focus offset signal FOFS and the tracking offset signal TOFS are generated such that the difference becomes 0, respectively, and the feedback control is performed.

Next, in step S5, as shown in FIG. 7, 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 in a direction approaching the disk. While the light and the pickup 2 rise, the voltage value of the focus error signal FEO is measured, and the S curve shown in FIG. 4 is measured. Here, FIG.
For example, in the S curve shown in FIG.
Assuming + above + f and − below −f, the peak value on the + side is taken as A + C, and the peak value on the − side is taken as B + D and stored. Next, step S5 turns on the focus servo control (the feedback loop is a closed loop).

The selection of the timing for turning on the focus servo control will be described with reference to FIG. Step S
At 4, the current of the focus coil increases to its maximum value, and the optical pickup 2 comes closest to the disk 1 (rises).
After that, in step S5, the current applied to the focus coil is reduced, and the optical pickup 2 is moved (falls) in a direction away from the disk 2. Focus error signal F
When the value of EO is a predetermined predicted value FEa (for example, 70
%), And then determine whether the voltage has dropped to the reference voltage ref1 (same as Ref in FIG. 4). In FIG. 7, the value of the focus error signal FEO at the moment when the predicted value FEa is exceeded is shown as FE3. The negative and positive peaks of the S-curve while the optical pickup 2 is rising are FE
1, FE2. The current reduction and this determination are repeatedly performed until the above result is obtained. When the value of the focus error signal FEO once exceeds a predetermined predicted value FEa, and then falls to the reference voltage ref1, the focus servo control is turned on, and normal focus servo control is started.

In FIG. 7, the portion indicated by the dotted line in the waveform shows the expected waveform change when the servo control is not turned on, and is shown by the solid line when the servo control is turned on. Waveform. In order to ensure the operation, the servo control is turned on after confirming that the sum signal ASO given from the preamplifier 9 has exceeded a predetermined threshold value ASa and recognizing that the disk 1 is present. Can be determined. ref2 and ASi indicate the reference voltage and the peak of the sum signal ASO. As described above, the condition for turning on the servo control is that the sum signal ASO given from the preamplifier 9 exceeds the predetermined threshold value and the focus error signal FEO (the signal in FIG. 4) which is the output signal of the focus balance differential amplifier 23F. 4-1) rises in the + direction with respect to the reference voltage, exceeds a predetermined threshold, and then falls again below the predetermined threshold. The timing at which the focus servo control is turned on is determined by the focus error signal FEO as described above.
Once exceeds the predicted value FEa, and then the reference voltage ref
Focus error signal FE
It is also possible that the value of O once exceeds the predicted value FEa and then a predetermined time has elapsed, or that the voltage has reached another predetermined voltage. In the above example, the optical pickup 2 is moved away from the disk 1 after being brought close to the disk 1, but this may be reversed.

Next, at step S6, the spindle motor 3
Is started, and the tracking servo control is turned on in the next step S7. Subsequently, in step S8, the servo control of the spindle motor 3 is turned on. Thereafter, in step S9, the optical pickup 2 is moved to a predetermined position for focus balance adjustment (for example, the center position of the area where TOC information is recorded), and the focus balance adjustment is started in step S10. EFM obtained from playback signal
While the A / D conversion is performed on the envelope signal, the optical signal is applied to the optical pickup 2 so that the envelope signal is moved from the center point on the S-curve in the waveform diagram of FIG. This excitation can be performed by adding a pseudo sine wave of about 200 Hz to the focus servo loop and vibrating the optical pickup 2 at this frequency.

In step S12, the position on the S-curve where the maximum point of the amplitude of the EFM envelope signal is located is detected.
Until the maximum point is found, steps S10, S11, S1
2 is repeatedly executed. During this time, in step S10, the focus balance signal FBAL is adjusted such that the position on the S-curve where the maximum point of the amplitude of the EFM envelope signal is at the reference voltage Ref. This adjustment can be performed in 16 steps of gain switching with a 4-bit signal, and the amount of balance can be changed by increasing or decreasing the gain. Note that the direction in which the absolute value of B + D increases becomes-.

In the next step S13, the above step S12
A + C> B + using the balance adjustment direction and the peak values on the A + C and B + D sides measured in the previous step 2 when the maximum point of the EFM envelope signal is obtained in
Do you judge whether it is D or not? If YES, the change value of the focus balance signal FBAL becomes + in the next step S14.
(Adjustment in a direction in which B + D becomes smaller) is determined. If YES, the following determination is made in step S15. Although not explicitly shown in the flowchart of FIG. 1, when the maximum amplitude point (the best point of the reproduction signal) of the EFM envelope signal is found in step S12, the balance amount at that time is stored, and stored in step 4. The two peak values A + C and B + D after the focus balance adjustment are added to the two peak values A + C and B + D in the S curve before the focus balance adjustment, by adding the focus balance amount after the adjustment.
The ratio of the absolute value of + D is calculated as B + D / A + C = K. In step S15, it is determined whether or not the ratio K is larger than a predetermined value K1. The predetermined value K1 and other predetermined values K2 to K4, which will be described later, are used to determine whether the symmetry of the S curve with respect to the reference voltage Ref is good or bad. For example, K1 = 0.5, K2 = 2, K3 = 0.2, K4 = 5
And The symmetry is best when K = 1, and K1
As the size becomes larger or smaller, the symmetry worsens. In this embodiment, when K is larger than 0.5 and smaller than 2, the symmetry is considered to be good.

If YES in step S15, the symmetry of the S curve is good, so the focus balance amount stored in step S12 is set in step S16 (F
It is output from the microcomputer data I / F 36 as a BAL value.) On the other hand, if K is not larger than K1, the symmetry of the S curve is poor, and it is further determined in step S19 whether the ratio K is larger than a predetermined value K3 smaller than the predetermined value K1. If YES, step S1 is executed in step S20.
The focus balance amount is set in the same manner as in step 6, and the focus offset is also set. That is, for example, if the ratio K is 0.3, the offset amount is changed for the portion corresponding to 0.3 to 0.5, and the balance amount is changed for the remaining portion corresponding to 0.5 for 1. . At this time, since the loop gain of the servo control system substantially decreases, the gain is increased considerably. When the ratio K is not larger than K3 in step S19, the symmetry of the S curve is extremely poor,
Since normal focus servo control is impossible, a display or a warning to urge the user to repair the device is displayed in step S2.
In step 1, the information is displayed on the display means 18. The content of the warning depends on the set value or the device, "Recording is dangerous.", "Use only for playback.", "Repair the device.",
"It is in a state of being very vulnerable to shock."

Returning to step S14, if the determination result is NO, that is, if the change value of the focus balance signal FBAL is-(adjustment in the direction in which B + D increases), the determination is made in step S17. If YES, any one of step S16, step S21, and step S22 is executed in the same manner as described above via step S18 or the subsequent step S19. That is, when the focus balance change value is-, B + D increases, so that the ratio K exceeds 1, and the symmetry of the S-curve may pass through the symmetric state and become asymmetric in the opposite direction.
In this case, the symmetry of the S curve is determined in steps S15 and S1.
As in the case of No. 6, the judgment is made in two stages.

Specifically, if YES is determined in the step S17, since the symmetry of the S curve is good, the focus balance is further adjusted in the step S16. On the other hand, if K is not smaller than K2, the symmetry of the S-curve is poor, and it is further determined in step S18 whether the ratio K is smaller than a predetermined value K4 that is larger than the predetermined value K2. If YES, in step S20, the same focus balance adjustment as in step S16 is performed, and the focus offset adjustment is also performed. That is, for example, if the ratio K is 4, the balance amount is changed by an amount corresponding to 2 with respect to 1, and the balance amount is changed from the remaining 2 to 4
Is adjusted by the offset amount. At this time,
Since the loop gain of the servo control system actually decreases,
Increase the gain by a considerable amount.

If K is not smaller than K4 in step S18, the symmetry of the S-curve is so bad that normal focus servo control is impossible, so that a predetermined display is made on the display means 18 in step S21. Returning to step S13, if the determination result is NO, that is, A + C <
If it is B + D, the process proceeds to step S22, and the same processing as in step S14 and thereafter is performed according to the focus balance change value +/-. In the first embodiment, step 16
Although only the focus balance is adjusted in step 20 and both the focus balance and the focus offset are adjusted in step 20, the adjustment of the balance and the offset may be switched.

Next, a second example of the focus control method in the optical disk recording / reproducing apparatus will be described with reference to the flowchart of FIG. In the flowchart of FIG. 8, those having the same step numbers are the same as those of the flowchart of FIG. 1, and therefore, different points will be mainly described. The contents of the ratio K and the values of the predetermined values K1 to K4 are the same as in the first embodiment. In FIG. 8, a step S29 is provided in place of step S2 in FIG. 1 to determine whether or not adjustment at the time of startup is necessary. Further, when the determination in step S29 is NO, the mode determination is executed by branching. Step S26 is provided. Also, instead of step S20, when the determination result is YES in step S18 or step S19, that is, when the symmetry of the S curve is poor (except in the case of extremely bad), K1
There is provided a step S24 for setting a considerable focus balance amount and storing an originally necessary adjustment amount.

Step S26 determines the operation mode of the information recording / reproducing apparatus.
The playback device determines whether the mode is the recording or playback mode or the search mode. Step S16 and step S2
After step 4, the flag F is set to 1 or 2 in step S2.
3 and S25 are provided. When the flag F is 1 or more, it indicates that the focus balance has been automatically adjusted. When it is determined in step 29 whether or not adjustment at startup is necessary, the flag F is used.
Is 2, the process from step S26 is performed without executing the series of steps from step S3 again. In the recording or reproduction mode, step S28 is executed to focus on the position where the best point of the recording signal or reproduction signal is obtained.
Set the focus balance amount with. In the case of the search mode, the focus balance amount corresponding to K1 is set.

That is, for example, in step S19, the ratio K
Is 0.3, the setting for performing the focus balance adjustment corresponding to K1 = 0.5 is performed, and the adjustment amount corresponding to K = 0.3, which is originally required, is stored in the memory. I do. After step S23 or S25, although not shown, the process returns and returns to step S1 again.
Either step S27 or S28 is performed via 29 and S26. As a result, the signal level for recording or reproduction can be set to the best and the signal quality can be improved. That is, when the ratio K is 0.3, an adjustment corresponding to 0.3 is performed to shift to the best point of the reproduced signal to increase the signal level. This is because it is desired to keep the S-curve as symmetric as possible in order to stabilize servo control such as focus search and response to disturbance.

In the search mode or the like, if the adjustment is made largely in the same manner as in the recording / reproducing, the symmetry of the S-curve is degraded, and the stability of the servo control may be lacking. Therefore, the stability of the servo control is ensured. Therefore, the predetermined value K1 = 0.5
Is performed. That is, the value is adjusted by a value corresponding to K1, which is a value smaller than the originally required value of K, that is, 0.5. The same applies to the case where YES is obtained in step S19. In the second embodiment, the case where the focus balance is adjusted in step S14 and subsequent steps has been described as an example. However, instead of adjusting the focus balance, the adjustment of the focus offset amount can be similarly performed. Also in this case, the focus offset amount is adjusted in each case according to the value of the ratio K as shown in FIG. In FIG. 1, step S16,
After step S20, in FIG. 8, after steps S23 and S25, TOC information is read, and the process returns.
It returns to step S1.

[0040]

As described above, according to the present invention, for example, the influence on the focus error signal by the spot displacement in the vertical direction of the optical axis and the displacement in the optical axis direction becomes the same,
As a result, it is possible to provide an optical disk reproducing device and an optical disk recording device that can stably execute focus search and focus servo control even if the S curve becomes largely asymmetric.

[Brief description of the drawings]

FIG. 1 is a flowchart showing a first example of a focus control method in an optical disk recording / reproducing apparatus according to the present invention.

FIG. 2 is a block diagram showing an MD recording / reproducing apparatus as an example of the apparatus of the present invention.

FIG. 3 is a block diagram showing a preamplifier in FIG.

FIG. 4 is a waveform diagram showing various modes of an S curve of a focus error signal in a focus search together with other signals.

FIG. 5 is a plan view showing a relationship between an arrangement of optical sensors used in the optical disk recording / reproducing apparatus of FIG. 1 and a light spot;

6 is a plan view showing an example of a state of a shift of a light spot in a four-divided sensor part in the optical sensor in FIG. 5;

FIG. 7 is a waveform diagram illustrating a focus search method in the apparatus of the present invention.

FIG. 8 is a flowchart illustrating a second example of the focus control method in the optical disc recording / reproducing apparatus according to the present invention.

[Explanation of symbols]

Reference Signs List 1 optical disk 2 optical pickup (constituting optical head together with magnetic field modulation head) 3 spindle motor (means for driving and rotating disk) 4 motor driver / tracking / focus control circuit (constituting two positioning means together with preamplifier 9 and block 10) 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 36 Microcomputer data

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5D117 BB03 DD03 DD09 FF09 5D118 AA18 BA01 BF16 CA11 CD02 CD11

Claims (2)

[Claims] 1. An optical disk reproducing apparatus for reproducing information recorded on an optical disk, means for driving the optical disk to rotate, an optical pickup for reproducing data from the optical disk by a laser beam, and the optical disk of the laser beam A plurality of divided sensors for receiving reflected light from, and a means for generating and returning a tracking error signal by calculating a plurality of output signals of the sensor, and positioning the optical pickup in a track direction of the optical disc. Means for generating and feeding back a focus error signal by calculating a plurality of output signals of the sensor, for positioning the optical pickup in a focus direction, and for demodulating means for reproducing information from the optical pickup and demodulating a reproduction signal. With respect to the focus error signal, Balance setting means for setting the balance between a plurality of output signals before the operation of the sensor in accordance with the balance amount; offset setting means for applying an offset voltage to the focus error signal in accordance with the offset amount; and positioning in the focus direction. In order to detect the best state of the reproduction signal by moving the optical pickup in the focus direction, the balance amount and / or
Alternatively, an optical disc reproducing apparatus having an adjusting means for adjusting the offset amount. 2. An optical disk recording apparatus for recording information on an optical disk, comprising: means for rotating and driving the optical disk; an optical head for recording data on the optical disk with a laser beam; A plurality of divided sensors that receive the reflected light of, and a means for calculating and outputting a tracking error signal by calculating a plurality of output signals of the sensor, and positioning the optical head in the track direction of the optical disc; Means for generating and feeding back a focus error signal by calculating a plurality of output signals of the sensor, for positioning the optical head in a focus direction, for recording information by transmitting and receiving signals to and from the optical head, and for modulating a recording signal A modulating means, and the focus error signal before the calculation of the sensor A balance setting means for setting a balance between the number of output signals according to the balance amount and / or an offset setting means for applying an offset voltage to the focus error signal according to the offset amount; and a means for positioning in the focus direction. Moving the optical head in the focus direction with respect to an adjustment unit that measures the characteristics of the focus error signal to adjust the balance amount and / or the offset amount; Adjusting means for adjusting the balance amount or the offset amount in order to detect the best state of the reproduction signal; and setting means for setting the best state balance amount or the offset amount of the reproduction signal in the recording or reproduction state. When the balance is not in the recording or playback state, the balance or the amount of balance differs from the recording or playback state. Optical disk recording apparatus characterized by having setting means for setting a set amount.