JPH08203091A - Optical information recording / reproducing apparatus and information recording / reproducing apparatus - Google Patents

Abstract

(57) [Abstract] [Purpose] The objective is to reduce the CPU load due to a low sampling frequency in a digital servo or due to a quantization error. In an optical information recording / reproducing apparatus for irradiating a recording medium having a plurality of optically identifiable information tracks with a light beam to record / reproduce information, a first actuator which moves in a direction traversing the tracks, A second actuator for moving the first actuator; a movement amount detecting means for detecting a movement amount of the first actuator;
Seek means for moving using the second actuator;
Seek holding means for holding the first actuator by the output of the movement amount detecting means during operation of the seek means,
The actuator holding means holds the first actuator in addition to the operation of the seek means, and the control loop band of the actuator holding means is narrower than the control loop band of the seek time holding means.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical information recording / reproducing apparatus for recording / reproducing information on / from an information recording medium using a laser beam, and more particularly to providing a track groove on a disc-shaped or card-shaped recording medium, The present invention relates to control of a laser beam spot of an apparatus for recording / reproducing information along this track.

[0002]

2. Description of the Related Art In an optical disk device, the light emitted from a semiconductor laser as a light source is narrowed down to a diameter of about 1 micron by an objective lens and irradiated onto the optical disk.

In order to focus the light spot narrowed down on the surface of the information recording medium of the optical disk, feedback loop control generally called focusing servo is used.

Feedback loop control called tracking servo is used to position the light spot on the information track on the medium surface.

These control loops typically have the following elements: An optical sensor that receives the reflected light from the disc. An amplifier that amplifies the output of the optical sensor. 3. Control stabilization compensator that suppresses the output of the amplifier to a predetermined level. It is composed of an objective lens actuator that is driven by power conversion by a control stabilization compensator.

The position error between the light spot and the optical disc surface in the focus direction is detected by the amount of light received by the optical sensor, and the actuator moves the objective lens in the direction perpendicular to the optical disc surface to control the light spot on the disc surface. .

Similarly, the position error between the track on the disk and the light spot in the track direction is detected by the amount of light received by the optical sensor, and the actuator moves the objective lens along the optical disk surface to control the light spot on the track. .

[0008]

However, in an actual device, an offset occurs in the position error signal in the focus direction and the track direction due to an offset of an electric circuit, an attachment error of an optical component, etc. It is an obstacle to construction. Therefore, a method of automatically adjusting the offset of the position error signal at the time of starting the apparatus has been considered. Many of these methods deliberately add some type of offset into the servo loop to seek offset correction that gives the best signal. For example, offsets of about 20 steps are sequentially applied to the focus servo loop, the amplitude of the tracking signal is measured, the offset that gives the maximum tracking error signal amplitude is found, and this is added to the servo loop as an adjustment offset.

Further, in recent years, digitization of the servo circuit of an optical disk has been vigorously carried out for the purpose of downsizing, cost reduction and high performance of the device. With the digital servo,
The position error signal obtained from the optical sensor is A / D converted, the position error amount is converted into a numerical value, and this numerical value is calculated by a digital circuit, a microprocessor, a DSP (digital signal processor), etc. to obtain an appropriate drive signal. It is configured to drive the actuator. In digital servo, discrete time control is always performed, but in this case, the sampling interval cannot be unnecessarily increased finely due to the relationship between the A / D conversion time and the digital signal processing time.

For example, even in the tracking servo which requires the fastest processing in the optical disk device, the sampling frequency is about 50 KHz at most.

Therefore, when performing digital servo, it is difficult to measure the signal amplitude for automatic adjustment when the apparatus is started because of this low sampling frequency. In other words, when trying to measure the tracking error signal, the maximum frequency of track crossing due to the eccentricity of the disk is 5 KHz to 1
Since it is about 0 KHz, at a sampling frequency of 50 KHz, only 5 to 10 sample points can be obtained per one cycle of the track crossing waveform. This makes it impossible to accurately measure the amplitude value or offset of the track crossing signal.

For the track crossing due to the eccentricity of the disk, one rotation of the disk causes the light spot to be eccentric (more precisely
Double) back and forth on the truck. At the moment when the transverse direction is reversed, the tracking error signal may not reach the amplitude value and may have a peak at a halfway value, and again the amplitude and offset of the track transverse signal cannot be measured accurately.

Therefore, a measure may be considered in which the frequency of the track crossing signal is monitored and the measurement at the low frequency and the high frequency is prohibited, but the measurement permission frequency cannot be widened in order to improve the measurement accuracy. However, the adjustment time was increased. Therefore, the adjustment accuracy must be compromised to some extent, and the control performance is degraded.

When measuring the above-mentioned track crossing signal amplitude, it is necessary to fix or intentionally move the objective lens. For this purpose, the position of the objective lens is measured,
Perform feedback control on the tracking actuator. On the other hand, in order to reproduce or record information necessary for the optical disk device, it is necessary to fix the objective lens so that it will not be shaken by the vibration due to the seek movement during the seek for moving the light beam to the desired track. However, in fixing the objective lens at the time of seeking, since the vibration due to the seek movement is large, it is necessary to increase the Fordback gain for fixing the objective lens. Therefore, in the objective lens fixed feedback control at the time of measuring the track crossing signal amplitude, the driving force due to the quantization error that always remains in the digital control is applied to the actuator largely, and the objective lens vibrates slightly. Therefore, it is difficult to measure the track crossing signal amplitude with high accuracy.

When the eccentricity of the disk is measured at 50 KHz, which is the same as the sampling frequency of the tracking servo, when the eccentricity data for one rotation of the disk is stored, the rotation speed is 3600 rpm, and 833 memories are required. It occupies a large part of the precious memory of the and has very poor memory efficiency.

[0016]

The present invention has been made to solve the above-mentioned various drawbacks and problems.
In an optical information recording / reproducing apparatus for recording / reproducing information by irradiating a recording medium having a plurality of optically identifiable information tracks with a light beam, the position of a spot of the light beam is moved in a direction crossing the information track. A second actuator for mounting the first actuator and moving the first actuator in a direction traversing the information track.
Actuator, a movement amount detecting means for detecting the movement amount of the first actuator, a seek means for moving the light beam to a target information track by using the second actuator, and a move means while the seek means is in operation. The first actuator is driven by the output of the amount detecting means, and the seek-time holding means for holding the first actuator is provided, and the first actuator is driven by the output of the movement amount detecting means except when the seek means is in operation. , And an actuator holding means for holding the first actuator, wherein a control loop band of the actuator holding means is narrower than a control loop band of the holding means during seek.

Further, a track error detecting means for detecting the positional deviation amount between the spot position of the light beam and the information track by the reflected light from the recording medium, and a sampling for sampling the output of the track error detecting means at a predetermined sampling period. Means and the output of the sampling means are calculated at a predetermined sampling period, and the outputs of the servo control means and the sampling means for driving the actuator at the predetermined sampling period are processed at the predetermined sampling period to measure the output of the track error detecting means. The servo control means is operated when aligning the position of the spot of the light beam with the track, and the measuring means is operated when measuring the output of the track error detecting means.

Further, by the second sampling means for sampling the output of the movement amount detecting means in the cycle of a predetermined sample synchronization or more, and the output of the second sampling means,
By moving the movement amount measuring means at the same time as operating the servo control means with the movement amount measuring means for measuring the movement amount of the first actuator and stopping the second actuator, the conventional problems Is solved.

Further, in an information recording / reproducing apparatus for recording / reproducing information by irradiating a recording medium having a plurality of optically identifiable information tracks with an optical beam, an error signal detecting means for detecting a tracking error signal, and an optical signal detecting means. A tracking servo means for irradiating a beam to cause the objective lens to follow the information track is provided, and the band of the tracking control loop at the time of reproduction is narrower than the band of the tracking control loop at the time of seek. By doing so, it is possible to accurately follow a precise servo loop during playback and achieve an early jumping action during seek.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A general outline of automatic adjustment of offset and the like of an optical information recording / reproducing apparatus according to the present invention will be described.

(1) Hardware Configuration FIG. 2 shows a block diagram of the hardware of the servo system of the magneto-optical disk device embodying the present invention. In the figure, 10 is a mechatronics, which is an optical system such as a light source, an objective lens, a signal processing sensor for recording / reproducing an optical disc according to a track of the optical disc, an electric system for processing the signal, and a mechanical operation. A mechanical system such as an actuator, a spindle motor, etc. is built in, and 9 is an R / R for demodulating a read signal from an RF signal which is an output signal from the mechatronics 10, modulating write data, and outputting a VFO amplitude signal. In the W signal processing system, 1 is a CPU, which controls the entire system including hardware, processes the VFO amplitude signal from the R / W signal processing system 9, 4 is a serial D / A, and 3 is a mechatronic 10 Is an AGC that controls and amplifies the amplitude of a servo signal such as a focus error signal, a tracking error signal, or the output of a serial D / A.
Is an A / D & D / A converter that performs A / D conversion of the output of the CPU and D / A conversion of voltage data by the CPU 1 to perform mutual signal conversion between analog and digital. 5 is A / D & D /
An AF / AT driver that amplifies the drive signal for autofocus / tracking from the A converter 2 to drive the actuator, and 6 is a drive signal for a linear motor that moves the pickup position from the A / D & D / A converter 2. Is an LM driver that amplifies. The external ROM 7 and the external RAM 8 are memories that store programs and temporary data used when the memory in the CPU 1 is insufficient.

The servo processing of this embodiment is software servo by the CPU 1. The automatic adjustment of the servo system is also performed by firmware processing in most of the CPU 1. Since the threshold setting of the track count comparator (not shown) and the offset adjustment of the AGC 3 which require high speed cannot be processed in the CPU 1, the serial D / A converter 4 sets a voltage to an external device outside the CPU 1. Hereinafter, description will be made while exemplifying the details of each unit.

(2) CPU1 A CPU of RISC (Reduced Instruction Set Computer) type, capable of high-speed processing and controlling the entire system,
16 * 16 = 3 because it has a built-in hardware multiplier
2-bit multiplication can be performed in 150 ns, and an 8-bit, 8-ch A / D converter is built in.

(3) A / D & D / A converter 2 The 8-bit A / D inputs 8ch by time division, and the conversion time for all channels during the 8ch scan operation is 1.7 μS.
The 8-bit D / A has 4ch output and a settling time of about 3 μs.

(4) Serial D / A4 It has a serial communication type 12ch, 8-bit D / A converter. The settling time is low at 300 μs.

(5) AGC3 The servo sensor output 8ch is received from the mechatronics 10, and each servo signal such as a focus (AF) error signal / tracking (AT) error signal / total light amount (SUM) signal is generated, and the servo signal is normalized. (AGC) operation is performed. In addition, the lens position sensor output from the mechatronics 10 is received to generate a lens position (lens / pos) signal, and the lens / position LED for detecting the lens position is
Turn on the PC.

(6) AF / AT driver 5 It has a bridge type output power operational amplifier for 2 channels and is composed of a power amplifier for autofocus / autotracking, and the maximum drive current to the actuator is, for example, 0.
7A.

(7) LM driver 6 A driver for a linear motor that sets the lens position and a driver for driving the voice coil, and has a maximum output of 2A.

(8) External ROM 7 and External RAM 8 The CPU 1 has a built-in ROM and RAM, but since it lacks in storage capacity, it also has external memory. It is mainly used for the processing part of the system control system and the processing that can be performed at low speed instead of the real-time processing of the servo. Even in the automatic adjustment system, a large memory area is required, and an external RAM is used in a portion that does not require high speed.

(9) R / W signal processing 9 The RF signal processing portion demodulates and outputs the reproduction signal from the mechatronics 10 and modulates the signal data to be recorded on the optical disk of the mechatronics 10 with a high frequency so that the inside of the mechatronics. Output to the electric system and the optical system. A signal processing unit that generates a hold value of the VFO amplitude necessary for automatic adjustment of the AF offset is also configured.

(10) Mechatronic 10 This is an abbreviation for mechanic electronics, which can mount a 3.5-inch magneto-optical disk, for example. It is composed of an ordinary magneto-optical disk head, a spindle motor for rotating the disk, and the like. In the mechatronics 10, there is an optical head of a separation optical type similar to that mounted in a normal magneto-optical disk device, and an objective lens mounted in a carriage which is a movable part can move in a focus direction and a tracking direction. It has become. Focus servo and tracking servo are performed by moving the objective lens. In addition, a lens position sensor that detects the relative position of the carriage and the objective lens in the tracking direction is provided, and is used to drive the carriage during tracking or to fix the position of the objective lens during seek. Used. This sensor is called an objective lens position sensor, and is also called a "lens-pository" sensor because it detects the lens position. This sensor detection method can be realized by, for example, fixing an optical projecting / receiving element such as a photo interrupter to the carriage unit and placing a light shielding plate engaged with the objective lens in the optical path of the photo interrupter. A linear motor is mounted on this carriage unit and operates as a second actuator.

With the configuration of each of the above parts, the signal from the optical head in the mechatronics 10 part becomes a servo signal normalized by the AGC 3, and this servo signal is A / D & D / A.
It is digitized by the A / D converter of the converter 2.

Explaining the focus servo loop, the focus error signal (AF in the figure) output from the AGC 3 is A / D converted into a digital value. Then, the CPU 1 performs a filter calculation for servo loop stabilization based on this digital value, outputs the calculation result to the D / A converter of the A / D & D / A converter 2, and converts it into an analog signal (AF DRV in the figure), AF / The AF driver amplifier of the AT driver 5 drives the focusing actuator in the mechatronics 10.

Similarly, the tracking loop also processes the tracking error signal (AT in the figure) output from the AGC 3, and has the same configuration as the focus servo loop. The signal output as AT DRV is the AF / AT driver 5 Mechatronics 10 by AT driver amplifier of
Drive the tracking actuator inside. These details will be made clear in the description below.

FIG. 1 shows a block diagram of servo system functions in the embodiment of the present invention.

Many automatic adjustments of the servo system are made by adjusting digital numerical levels inside the CPU 1. Partial external serial D / A4 is used.

(A) Focus Servo System The AF error A / D of the AF error A / D block 21 is converted from the data inputted from the AGC 3 into the A / D converter part of the A / D & D / A converter 2 and converted into a digital value.
Shown as D value. The AF error A / D value output of the AF error A / D block 21 is added to the data of the AF offset 22 by the adder 23 to become the offset adjusted AF error data. The data indicated by the monitor point 24, which is the output of the adder 23, is the basis of the AF error signal, and is used for an error signal for focus servo or a monitor for detecting out-of-focus.

In the automatic adjustment operation, this AF offset 2
The value of 2 is actually set to various values and shaken for trial, and the amplitude of the AT error signal or the amplitude of the RF signal is monitored to find the best focus point.

The data indicated by the monitor point 24 is calculated by the phase compensation filter 25, and this data is multiplied by the variable control signal of the variable gain variable block 26 for the loop gain adjustment by the multiplier 27 to obtain the A / D & D / A converter. 2 to the AF drive D / A converter unit 28.

(B) Tracking servo system The structure is basically the same as the focus servo system. AG
The data input from C3 to the A / D converter portion of the A / D & D / A converter 2 and converted into a digital value is shown as the output of the AT error A / D block 31. A
The output of the T error A / D block 31 is added to the AT offset data 32 by the adder 33 to be AT error data whose offset has been adjusted. The AT offset 32 corrects the offset according to the lens position in addition to the DC offset.

In the automatic adjusting operation, the offset is measured by the signal amplitude when the track crosses, which appears at the monitor point 34 when the AT offset is zero. Determine the AT offset value of the AT offset 32 according to the measured value,
The data indicated by the monitor point 34 is calculated by the phase compensation filter 35, this data is multiplied by the variable control signal of the variable gain variable block 36 for loop gain adjustment by the multiplier 37, and the AT of the A / D & D / A converter 2 is multiplied. Drive D /
It is output to the A converter unit 38. At that time, the threshold value of the AT binarization threshold D / A 39 is set.

The AT actuator needs to be driven by the jump control 40 and the positive / negative servo drive in addition to the tracking servo, which is represented by the switch 41 in the drawing. The output of the switch 41 is AT drive D / A.
Powered at 38 drives the AT actuator.

(C) Len-Positive Servo System Similar to the focus servo system, the LP output indicating the lens position of the AGC 3 is digitized by the A / D converter portion of the A / D & D / A converter 2 and the lens-position error A / D 51 The data is used as data, and the LP offset value of the LP offset 52 is added by the adder 53 at the first stage to become the data of the len-pos monitor point 54. Next, correction calculation is performed by the phase compensation filter 55, and the LP drive offset 5
The LP drive offset value from 6 is added by the adder 57, and is referred to by various functional modules as adjusted lens-positive data. Here, since gain accuracy is not required, unlike the focus servo system, gain adjustment is not performed.

When the amplitude of the AT error signal is measured, the track is forcibly traversed, so a low-frequency drive offset 5 is used as drive offset data at the output stage of the lens-position servo.
6 is added by the adder 57 to vibrate the objective lens.

(D) Trace Servo System The data of the positive / negative error A / D 51 is adjusted by adding the trace offset value by the trace offset 62 by the adder 63 to form the monitor point 64, and then corrected by the phase compensation filter 65. Calculated and LM drive D for linear motor
It is output as an analog value at / A68 and used in various functional modules.

The trace offset 62 has a function of canceling the eccentricity when the disk rotates. One rotation 1 in synchronization with the rotation of the spindle motor of the disk rotation motor
A spindle rotation synchronization counter that counts by about 00 counts is configured in the CPU 1, and trace data that corresponds to the eccentricity is updated in synchronization with the spindle rotation synchronization counter at the time of tracing.
At 4, the eccentricity component is removed to obtain a positive / negative signal.

Similar to the AT servo, the phase compensation filter 6
Switching between the output of No. 5 and the seek control block 66 is realized by a switch 67. The output of the switch 67 is input to the LM drive D / A 68 and drives the linear motor that moves the position of the optical system.

(E) SUM signal system A signal obtained by adding all the outputs of the servo sensors divided into a plurality is called a SUM signal. A / D & D / A for SUM signal
The A / D section of the converter 2 converts it into digital data, and S
The threshold data for binarizing the UM signal is determined, or the AF deviation detection threshold data based on the SUM signal is determined.

[Explanation of Each Algorithm] Hereinafter, coarse adjustment, fine adjustment, and deviation detection level in the AF offset, and coarse adjustment, slice level, and deviation detection level in the AT & SUM offset will be described.
Further, each eccentricity measurement will be described in detail.

(1) AF offset (coarse adjustment, fine adjustment,
Detachment Detection Level) FIG. 3 shows a portion of the automatic adjustment function block diagram (FIG. 1) particularly extracted for AF offset automatic adjustment.

Focus offset automatic adjustment is largely 2
It is divided into two automatic adjustments. One is offset adjustment using the amplitude of the tracking error signal as an index, and the other is offset adjustment using the amplitude of the ID part VFO signal as an index. The former is called “automatic AF offset adjustment by AT signal amplitude”, and the latter is called “AF offset adjustment by VFO amplitude”.

After the disk is rotated at a constant speed and the laser is turned on and AF is pulled in, "automatic AF offset adjustment by AT signal amplitude" is performed. After that, the AT is pulled in, and “AF offset adjustment by VFO amplitude” is performed in the trace state. These two automatic adjustments are independent modules, and when all the automatic adjustments are performed, the AF offset is finally set by "AF offset adjustment by VFO amplitude".

By combining these two AF automatic adjustments, it is possible to construct an AF offset automatic adjustment that can cope with a slight difference between AT-Max and VFO-Max. For example, the amount of AF offset actually shaken is limited by "automatic AF offset adjustment based on AT signal amplitude". Alternatively, an intermediate level between the offset value in “AF offset automatic adjustment by AT signal amplitude” and the offset value in “AF offset adjustment by VFO amplitude” is set as the final set AF offset.

Next, the "automatic AF offset adjustment by the AT signal amplitude" and the "AF offset adjustment by the VFO amplitude" will be described in detail.

(A) "AF offset automatic adjustment by AT signal amplitude" First, the servo state during automatic adjustment will be described. AF
While the servo is being applied, and the AT actuator for tracking servo adjustment is being held in the center by the positive / negative servo, the focus servo offset is automatically adjusted.

On the disc signal surface, for example, according to the three-beam method, the tracking spots are arranged at positions shifted on one side of one track, and the ± 1st order light on both sides is received by a photosensor for tracking detection. The difference between the sensor output signals becomes the AT signal. Further, in the push-pull method, a reflected wave of a beam divided into two is received by a photosensor divided into four, and a tracking error signal is made an AT signal. A
In the T-servo state, the position of the objective lens is controlled so that the difference between the sensor output signals becomes zero.

The amplitude of the AT signal is affected by the function of AGC3. When the normalized response speed of AGC3 is increased,
The AT signal is distorted due to the influence of the sum signal. Therefore, it is necessary to peak-hold the normalized signal of AGC 3, that is, the sum signal. The detection of the AT signal amplitude needs to be in this peak hold state.

The AT-actuator is fixed in the approximate center of the movable range by the lens-position servo, but at this time, the objective lens is vibrated slightly to ensure that the light spot crosses the track. A drive signal having a constant cycle of a sine wave is applied to the lens-position servo loop to vibrate the objective lens. For example, a vibration with a cycle of about 100 Hz and about several 10 μm is generated. This drive signal is LP drive offset 5
6, the signal of the LP offset 52 is added to the output of the LP error A / D 51 of FIG. 3 by the adder 53, the phase is compensated by the phase compensation filter 55, and the output signal of the LP drive offset 56 is added by the adder 57. As described above, it is added immediately before the output of the positive / negative servo to the AT drive D / A 38. This is a problem of quantization error due to the digital signal of the len-posi servo. By adding a sine wave as the target value of the ren-posi servo loop, it is better to add the signal immediately before the output to the AT drive D / A 38 to obtain smoother vibration. This is because it can be done.

For smooth vibration, it is necessary to set the band of the positive / negative servo narrow. On the other hand, the lens-position servo during seek needs to suppress the vibration of the objective lens during seek as much as possible, so that the band needs to be wide, that is, the gain needs to be high. Therefore, by the jump control of the information track, the band of the len-pos servo during the seek is widened, and the band of the len-pos servo is narrowed at other times. This is the phase compensation filter 55 in the CPU 1.
It is possible to change the gain and the filter characteristic of at the seek time and at other times. This can be easily realized by the software servo based on the program stored in the ROM using the CPU 1 without any harmful effect.

By widening the range positive / negative servo band during seek and narrowing the range positive / negative servo band at other times, the vibration of the objective lens can be suppressed as much as possible during the seek, and the objective lens detected by the track count can be used. It eliminates errors caused by vibration of the objective lens in position and movement speed, and enables stable seek.

By narrowing the lens-position servo band during automatic AF offset adjustment, the objective lens can be moved smoothly, and even tracks without eccentricity can be moved across tracks. Distortion of the signal waveform due to various vibrations is eliminated, A
The accuracy of measuring the amplitude of the T signal can be improved.

Furthermore, by narrowing the lens-position servo band other than during seek, it is possible to reduce the power consumption and suppress the heat generation of the actuator by adopting a structure in which a driving force is not unnecessarily applied to the actuator.

The adjustment procedure of the AF offset automatic adjustment based on the AT signal amplitude will be described below. AF-S as the output waveform of the AF error signal, which is measured when the AF is pulled in
The amplitude range of the offset applied to the AF servo loop for adjustment is determined based on the peak value data of the character. For example, it is half of the S-shaped peak. Half of this S-shaped peak
The offset is changed with a resolution divided into eight. plus·
Measure 17 points in both negative directions and zero point.

First, with the offset being zero, the amplitude of the AT signal is measured, and the amplitude value and the offset value are associated and stored. Next, the offset is changed in the negative direction step by step with the above resolution, and the AT signal amplitude value at each step and the given offset are stored in association with each other. This is performed within the range, that is, up to 8 steps.

At this time, the maximum value of the AT signal amplitude is determined in parallel, and 80% of the maximum value is measured during each step measurement.
If an AT signal amplitude below is measured, a sequence is taken that does not increase the absolute value of the offset any further. This is to prevent the focus state from being extremely deteriorated and defocused.

Next, the offset is changed again to zero, and the measurement in the plus direction is performed similarly to the minus direction.

After the measurement of all points is completed, AT
Find the maximum signal amplitude value. And the maximum value of 80
Calculate the AF offset that gives a% amplitude. This 80
The offset value below% is obtained by linear interpolation from the previous and next offset values.

80% in each of the plus and minus directions
The average of the lowered offsets, that is, the center is set as the set offset.

Finally, the offset is gradually changed up to the set offset. A sudden change is not good because it causes defocus. Further, as the threshold level for detecting the out-of-focus state, an offset value above 80% may be set.

Next, the AT signal amplitude measuring method will be described. Basically, peak hold and bottom hold operations are performed. The attack / hold characteristics are set so that the average value of the peak value or the bottom value can be measured correctly and that it does not respond sharply to noise.
At this time, half the difference between the peak and the bottom is the amplitude. Then, the processing is performed at the 50 KHz servo interrupt timing. The output value of the AT error A / D 31 is read, and 1/8 of the difference is added to the attack characteristic and 1/1024 of the difference is subtracted from the hold characteristic according to the magnitude relation of the difference with the peak data or the bottom data. .

In parallel with the above processing, peak / bottom data are integrated and averaged for each 50 KHz sample. For example, data for one rotation of 16.6 ms is averaged for one point of the applied focus offset during measurement.

Next, a flow chart will be described. FIG. 4 shows a main flowchart of the AT signal amplitude measurement according to the present invention, and FIG. 5 shows a flowchart of the interrupt module.

For example, assume that the AT signal amplitude across a track is ± 100. Here, the method of detecting the peak value on the +100 side will be described, but the method of detecting the negative peak (bottom) on the −100 side can be easily realized by only considering the sign or the magnitude relationship, and therefore the description thereof will be omitted.

The peak hold process is started in step 1 (s1). First, the averaging register or the waveform peak value register is initialized (s
1). The peak value register is a register that is an output of the peak hold processing of the AT error signal, and the integration register is an integration register for averaging the peak hold values for a certain period. The integration count register indicates the number of times the peak hold value has been integrated in the integration register. Therefore, the average peak value is "value of integration register" / "value of integration count register"
Can be calculated by

When the start flag is set in step s3, the peak hold process in the interrupt process described later with reference to FIG. 5 is started.

In step s4, a 5 ms timer is started to wait for the peak value register to converge from the initial value to the actual peak value.

In step s5, it is determined that 5 ms have elapsed, and then in step s6, the averaging start flag is set. After that, the peak hold processing is continuously performed in the interrupt processing shown in FIG. 5, and the peak value integration processing is further started.

In step s7, a timer for setting the averaging time is started, in this case, one rotation for one rotation of the disk.
A time average of 6.6 ms is decided. By averaging during one rotation of the disc, the variation in the circumferential direction of the disc can also be averaged.

When it is determined in step s8 that 16.6 ms has elapsed, the start flag is reset in step s9, and the peak hold and the integration process in the interrupt process are stopped.

After that, the average value is calculated in step s10. By dividing the value of the integration register by the value of the integration number register, the average peak value of the average AT signal amplitude during one rotation of the disk can be calculated.

Next, the interrupt processing module will be described with reference to FIG.

This interrupt processing is started at 50 KHz which is the basic sampling frequency of the servo system. When this module is activated in the interrupt processing, it is first checked in step s22 whether or not the start flag is set. Until the start flag s3 is set in the main flow chart of FIG. 4, the process goes to the return of step s23, and the module ends.

When the start flag is set, step s
The process proceeds to 24 and peak hold processing is performed. At step s24, first, the AT error A to which the AT error signal is input is input.
The data of / D31 is read, and the value of the AT error A / D31 is compared with the peak value of the peak value register in step s25. A / D of read AT error A / D31
If the value is larger than the peak value, step s26
Go to, increase the peak value data in the peak value register,
At this time, instead of setting the actual A / D value as the peak value,
The peak value data is increased by 1/8 of the difference between the A / D value and the previous peak value. That is, the value of peak value = peak value + {(A / D value-peak value) / 8} is set in the peak value register as the peak value. This can prevent malfunction of the peak hold due to scratches on the disk or noise.

On the contrary, when the A / D value is smaller than the peak value, the hold operation is performed. In this case, peak value = peak value + {(A / D value−peak value) / 10
24} is set in the peak value register. That is, at this time as well, not only the peak value data is held, but the difference between the A / D value and the peak value up to the previous time is reduced by 1/1024 to slowly reduce the peak value, thereby causing a peak due to a scratch or noise on the disk. The malfunction of the hold can be prevented.

When the peak value operation is completed, the averaging start flag s6 is checked, and if it is not set, the module is ended in step s29. When passing through this route, it is during a 5 ms timer period waiting for the peak value data to converge to the actual peak value.

If the averaging start flag s6 is on, the process proceeds to step s30, where the value of the peak value register is integrated in the integration register, and the integration count register is incremented by 1 to count the integration count. Then, in step s31, the interrupt ends.

16.6 m of the main flow chart of FIG.
When the timer of s times out, the start flag is reset (s9), so neither peak hold processing nor integration processing is performed.

In this way, the AT error signal at the time of crossing the track is from 5 KHz to 10 KHz and the sampling frequency is 50 K only with the data of the discrete sampling points of 50 KHz.
Accurate peak values and bottom values can be determined even though the values are close to Hz, and eventually it becomes possible to measure the amplitude value and offset value of the AT error signal. Further, the peak value is manipulated to ⅛ or 1/1024 of the data difference, so that it is resistant to noise and the convergence time can be appropriately set. By making it strong against noise in this way, AT
Even if the SUM signal is very noisy as compared with the error signal, the amplitude at the time of crossing the track can be accurately measured. In other words, the same algorithm is used to calculate the SU that is a signal obtained by adding all the outputs of the servo sensors divided into a plurality of parts.
Good measurement results can be obtained even when used for the amplitude and offset of the M signal.

(B) "AF offset adjustment by VFO amplitude" First, the servo state at the time of automatic adjustment will be described. AF
Perform with servo, AT servo, and trace servo applied.

V of the ID part which records the bit synchronization signal and sector address in each sector of the track of the disc
It is necessary to hold the amplitude of the FO signal.
In order to obtain the timing, the ID reproducing system must operate normally and the address can be reproduced.

Next, the adjustment procedure will be described. As in the case of (a) “Automatic AF offset adjustment based on AT signal amplitude” described above, A measured at the time of AF pull-in
The offset range applied to the AF servo loop for adjustment is determined based on the F-S peak value data. For example, it is half of the S-shaped peak.

The offset is changed with a resolution obtained by dividing half of this peak into eight equal parts. Measure 17 points in both plus and minus directions and at zero point.

First, the VFO signal amplitude is measured with the offset being zero, and the amplitude value and the offset value are associated and stored. Next, the offset is changed in the negative direction step by step in the above-described resolution, and the VFO signal amplitude value at each step and the given offset are stored in association with each other. This is performed within the range, that is, up to 8 steps.

Further, at this time, in parallel, the maximum value of the VFO signal amplitude is discriminated, and the maximum value of 80 is detected during each step measurement.
If VFO signal amplitudes below% are measured, then a sequence is taken that does not further increase the absolute value of the offset. This is to prevent the focus state from being extremely deteriorated and defocused.

Next, the offset is changed again to zero, and the measurement in the plus direction is performed similarly to the minus direction.

When the measurement of all points is completed, VF
Find the maximum of the O signal amplitude values. And the maximum value of 8
The AF offset that gives an amplitude of 0% is calculated. This 8
The offset value below 0% is obtained by linear interpolation from the preceding and following offset values.

80 in each of the plus and minus directions
The average of the% decrease offsets, that is, the center is used as the set offset. Finally, the offset is gradually changed to the set offset. Here, a sudden change is not good because it causes defocus. Further, as the out-of-focus detection threshold level, an offset value above 80% may be set.

Next, the VFO signal amplitude measuring method will be described. Process this VFO signal amplitude measurement at 1/8 of the 50 KHz servo interrupt timing. The VFO amplitude data detected by the R / W signal processing system 9 by the RF signal from the mechatronics 10 is input to the CPU 1 and C
The VFO amplitude data which has been digitized by the A / D converter of PU1 is read, and integrated and averaged for each ⅛ sample of 50 KHz. For example, average the data for 10 ms for each AF offset point.

Thus, the rough adjustment, the fine adjustment, and the deviation detection level for setting the AF offset value have been described. In this way, for example, the intermediate level between the offset value in “AF offset automatic adjustment by AT signal amplitude” and the offset value in “AF offset adjustment by VFO amplitude” is set as the final set AF offset. Then, this offset value is stored in the memory, and the output level of the AF offset 22 of FIG.
Is added to

(2) AT & SUM offset (coarse adjustment,
Slice Level, Deviation Detection Level) Hereinafter, the coarse adjustment in the AT & SUM offset, the slice level, and the deviation detection level will be described in detail. FIG. 6 shows a block configuration of the automatic adjustment function, in particular, a portion required for automatic adjustment of AT offset & SUM offset is extracted.

"AT & SUM offset automatic adjustment" is performed after the disk is rotated at a constant speed, the laser as a light source is turned on, the AF is pulled in, and the AF offset is automatically adjusted by the AF offset (1) AF offset described above.

(A) "AT & SUM Automatic Offset Adjustment" First, the servo state during automatic adjustment will be described. AF
AT & SUM with AT actuator held in center by servo
Performs automatic offset adjustment. The AT signal amplitude is affected by the AGC function. When the normalized response speed of AGC3 is increased, the AT signal is distorted due to the influence of the sum signal.
Therefore, it is necessary to peak-hold the normalized signal of AGC 3, that is, the sum signal. Therefore, AT error A / D3
In No. 1, it is necessary to be in this peak hold state.

The AT-actuator is fixed to the approximate center of the movable range by the lens-position servo. At this time, the objective lens is vibrated slightly to compensate for the light spot crossing the track. A drive signal having a constant cycle of a sine wave is applied to the LP drive offset 56 to the lens-position servo loop to vibrate the objective lens. For example, a cycle of about 100H
Vibration of about 10 and several ten μm is generated.

This drive signal is added just before the D / A output of the positive / negative servo as in the configuration of FIG. This is a problem of quantization error due to digitization of A / D, and it is possible to make a smooth vibration by adding a signal immediately before D / A output, rather than adding a sine wave as a target value of the lens-position servo loop. This is because. Also, for smooth vibration, it is necessary to set the band of the positive / negative servo narrow.

Next, the adjustment procedure will be described. From the AT error A / D 31 data, the peak and bottom of the AT error signal when crossing the track are measured. The average of the peak value and the bottom value is taken as the AT offset, and this is added to the output of the AT error A / D 31 in the CPU 1 by the adder 33 (subtraction on the firmware).

Further, in order to set the threshold level of the AT signal binarizing comparator in the AGC-IC, the measured AT offset value is converted at a specified ratio corresponding to the hardware and set in the serial D / A4. .

Similarly, the peak value and the bottom value of the SUM signal at the time of crossing the track are measured from the SUM-A / D data. The average of the peak value and the bottom value is used as a SUM offset, and this is used as a binary threshold level for the SUM signal in each module. Since binarization of the SUM signal does not use an external comparator, it is not necessary to set it to D / A. Also, the average of the bottom value and the zero level,
That is, the median value is used as the threshold level for detecting the AF deviation by the SUM signal.

Next, the AT & SUM signal offset measuring method will be described. The basic measurement method is the same for both the AT signal and the SUM signal, and the case of the AT signal will be mainly described below.

Basically, it operates by peak hold and bottom hold. The attack / hold characteristics are set so that the above-described averaging effect and the noise is not sharply responded to. Then, the average value of the peak value and the bottom value is used as the offset. Also, half the difference between the peak value and the bottom value is the amplitude. This is processed at the 50 KHz servo interrupt timing.

Read the output value of the AT error A / D 31,
According to the magnitude relation of the difference between the peak data and the bottom data, 1/8 of the difference is added to the attack characteristic, and 1/1024 of the difference is subtracted from the hold characteristic.

In parallel with the above processing, the peak / bottom data is integrated and averaged for each 50 KHz sample. For example, in the current version, 1 rotation is 1 point
The data for 6.6 ms is averaged. In the case of a SUM signal, the output value of the AT error A / D31 to be read is the SUM
-Replace with A / D71.

Since the AT & SUM signal offset measuring method is the same as the AT signal amplitude measuring algorithm described in FIGS. 4 and 5, detailed description thereof will be omitted.

(3) Measurement of Eccentricity A part of the automatic adjustment function that is particularly necessary for measuring the eccentricity is extracted and shown in FIG. First, the disk is rotated at a constant speed, a laser as a light source is turned on, AF is drawn, and after AT is drawn, the amount of eccentricity of the disk is measured in a state where the trace operation for track following is not performed.

The amount of eccentricity of the disk is measured by the len-pos signal when the AT servo is applied while the carriage is stopped. The rotation phase of the disk is used to know the rotation phase, and the eccentricity of the disk is measured and stored in synchronization with this. For example, eight rotations of the disk are averaged.
The data amount for one rotation is about 104. This eccentricity amount data is used to cancel the eccentricity amount from the positive / negative signal so that the carriage does not follow the eccentricity during the trace operation.

In FIG. 7, the adder 63 adds a trace offset 62 to the len-pos signal of the LP error A / D 51.
The trace offset amount is added (actually, the addition is a subtraction), and the eccentricity amount is set in synchronization with the disk rotation.

Next, the automatic adjustment of the eccentricity measurement will be described. The servo state during automatic adjustment is performed with AF and AT pulled. In addition, it is not essential under the condition that there is no external vibration, but in consideration of external vibration, it is necessary to fix the carriage somewhere.

Further, the adjustment procedure will be described. 11
Clear 0 data tables. 1/50 KHz
At the timing of 4, the LP error A / D 51 LP error A / D
The D value is accumulated in the phase table indicated by the rotation synchronization counter of the disc. Sync counter is 1 at 50 KHz
Since it is / 8, LP error A / D51 of 2 samples at each 1 phase
A / D value data of When the time for 8 rotations has elapsed, the average is averaged over the entire table.

First, the averaging process will be described. The average eccentricity amount data for each phase of the disk rotation is obtained, and the average of the eccentricity amounts for all phases, that is, for one revolution is calculated. Since this average is the DC component of the eccentricity amount data table, this DC component is subtracted from the eccentricity amount data of each phase to obtain an eccentricity amount table without the DC component.

The three types of specific algorithms have been described above. All of them are algorithms for obtaining and processing the average value of AF offset, AT offset, eccentricity, etc., but the present invention is not limited to this algorithm, and other algorithms may be used.

[0120]

As described above, according to the present invention, the problem that the sampling frequency in the digital servo cannot be increased or the problem of quantization error can be solved.

At the seek time and at other times, the band of the lens-position servo loop for fixing the objective lens is changed so that the objective lens can be intentionally moved smoothly with a narrow range-position servo band at the time of measuring the servo signal when crossing the track. By vibrating, even if the disc has no eccentricity, it is possible to always realize track crossing, and by moving smoothly, the accuracy of amplitude measurement is improved.

Further, even with a limited sampling frequency in digital servo, an accurate servo signal amplitude can be captured by a simple memory operation for each sample timing, and the accuracy of amplitude measurement is improved.

The eccentricity of the disk can be accurately measured by measuring and storing the len-pos signal in synchronization with the sampling timing of the digital servo and in synchronization with the rotation of the disk.

With these, a highly accurate servo can be realized,
A high-density, large-capacity optical disc can be realized. Further, by performing automatic adjustment according to the state of the disc and the state of the device at that time, it is possible to reduce the precision of optical parts, the precision of the disc, or the precision of adjustment at the time of manufacturing, and it is possible to manufacture the device at low cost. it can.

[Brief description of drawings]

FIG. 1 is a servo system automatic adjustment block diagram of a magneto-optical disk apparatus embodying the present invention.

FIG. 2 is a hardware block diagram of a magneto-optical disk device embodying the present invention.

FIG. 3 is a block diagram of an AF offset automatic adjustment of the magneto-optical disk device embodying the present invention.

FIG. 4 is a flowchart of tracking signal amplitude measurement.

5 is a flowchart of tracking signal amplitude measurement showing a part of the flowchart of FIG. 4 in detail.

FIG. 6 is an AT & of a magneto-optical disk device embodying the present invention.
It is a SUM offset automatic adjustment block diagram.

FIG. 7 is an eccentricity measurement block diagram of a magneto-optical disk device embodying the present invention.

[Explanation of symbols]

 1 CPU 2 A / D & D / A converter 3 AGC 5 AF / AT driver 10 Mechatronics 21 AF error A / D 22 AF offset 25 Phase compensation filter 28 AF drive D / A 31 AT error A / D 32 AT offset 35 Phase compensation filter 38 AT drive D / A 51 LP error A / D 56 LP drive offset

Claims (7)

[Claims] 1. An optical information recording / reproducing apparatus for irradiating a recording medium having a plurality of optically identifiable information tracks with a light beam to record / reproduce information, wherein the position of the spot of the light beam is set to the information track. A first actuator for moving the first actuator in a direction crossing the information track, a second actuator for mounting the first actuator, and a second actuator for moving the first actuator in a direction crossing the information track, and a movement amount of the first actuator. A moving amount detecting means for detecting the light beam, a seek means for moving the light beam to a target information track by using the second actuator, and an output of the moving amount detecting means during operation of the seek means. Seek holding means for driving the first actuator to hold the first actuator, and the seek means The first actuator is driven by the output of the movement amount detecting means except during the operation of
And an actuator holding unit for holding the actuator, wherein the control loop band of the actuator holding unit is narrower than the control loop band of the holding unit during seek. 2. A track error detecting means for detecting a positional deviation amount between the spot position of the light beam and the information track by the reflected light from the recording medium, and a signal amplitude of an output of the track error detecting means. And an amplitude measuring holding unit that drives the first actuator by the output of the movement amount detecting unit during operation of the amplitude measuring unit and holds the first actuator. The optical information recording / reproducing apparatus according to claim 1, wherein the control loop band of the holding means is narrower than the control loop band of the holding means during seek. 3. An optical information recording / reproducing apparatus for irradiating a recording medium having a plurality of optically identifiable information tracks with a light beam to record / reproduce information, wherein the position of the spot of the light beam is set to the information track. An actuator that moves in a direction traversing, a track error detection unit that detects the amount of positional deviation between the spot position of the light beam and the information track by the reflected light from the recording medium, and the output of the track error detection unit. Sampling means for sampling at a predetermined sampling period, servo control means for calculating the output of the sampling means at the predetermined sampling period and driving the actuator at the predetermined sampling period, and output of the sampling means for the predetermined sampling period Output at the track error detection means after processing at the sample period A measuring means for measuring, wherein the servo control means is operated when aligning the position of the spot of the light beam with the information track, and the measuring means is used when measuring the output of the track error detecting means. An optical information recording / reproducing apparatus characterized by operating the. 4. The measuring means has a memory for measuring the amplitude of the track error detecting means, compares the output value of the sampling means with the value of the memory at the predetermined sampling period, and outputs the comparison result. 4. The optical information recording / reproducing apparatus according to claim 3, wherein the amount of change in the numerical value of the memory is changed in accordance with the above. 5. The optical information recording / reproducing apparatus according to claim 4, wherein the numerical change amount is an amount proportional to a difference between an output value of the sampling means and a value of the memory. 6. An optical information recording / reproducing apparatus for irradiating a recording medium having a plurality of optically identifiable information tracks with a light beam to record / reproduce information, wherein the position of the spot of the light beam is set to the information track. A first actuator for moving the first actuator in a direction traversing the information track, a second actuator equipped with the first actuator for moving the first actuator in a direction crossing the information track, and a movement amount of the first actuator. A movement amount detecting means for detecting the track error detecting means for detecting the positional deviation amount between the spot position of the light beam and the information track by the reflected light from the recording medium, and the output of the track error detecting means. A first sampling means for sampling at a predetermined sampling period; and an output of the first sampling means The calculation is performed at a predetermined sampling period, and the first sampling is performed at the predetermined sampling period.
And servo control means for driving the second actuator, second sampling means for sampling the output of the movement amount detection means in a cycle of the predetermined sampling cycle or more, and output of the second sampling means A moving amount measuring unit for measuring the moving amount of one actuator, and the servo control unit is operated in a state where the second actuator is stopped, and at the same time, the moving amount measuring unit is operated. Optical information recording / reproducing device. 7. A motor for rotating the recording medium, and a rotation phase counter for indicating a rotation phase of the motor, wherein the movement amount measuring means measures the movement amount in synchronization with the value of the rotation phase counter. The optical information recording / reproducing apparatus according to claim 6, which is characterized in that.