JPH07262723A - Radial feed control system in disk device - Google Patents

Abstract

PURPOSE:To obtain a control system capable of highly accurately and stably performing the radial feed of disk device even when an inexpensive linear motor having an inferior frequency characteristic is used. CONSTITUTION:In place of a track error low band component-detecting means of a radial feed servo loop, a track error correcting means 9 composed of an upper limit level judging means 101, a lower limit level judging means 102, an adding means 103 and an amplifying means 104 is installed. Thus, when a track error is in a pickup tracking servo loop followable range, the radial feed servo loop becomes a nonsensitive zone not to be operated, and hence the stability is not damaged. And, when the track error is outside the pickup tracking servo loop followable range, a low band gain of radial feed servo is secured by driving the linear motor at a prescribed fixed control value, and the stability of the whole tracking control system is not influenced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control system of an apparatus for recording / reproducing information on / from a disk-shaped medium, and more particularly to a disk apparatus capable of accurately tracking information tracks spirally formed on the disk. The present invention relates to a radial feed control method.

[0002]

2. Description of the Related Art In an optical disk apparatus, an information track position is formed by moving or positioning an optical spot irradiated by an optical head on the information track spirally formed on the disk, or by rotating the disk. Information is recorded / reproduced by following changes.

In such an apparatus, the light spot is accurately positioned in the center of the information track so that the light spot can be accurately tracked even if the track position changes, or the track from the current track to an arbitrary target track can be accurately and at high speed. Tracking control to move is required. The movement of the light spot position in the disk radial direction for following the track position fluctuation and for moving between tracks is generally performed by operating the objective lens that focuses the laser light on the information track. . However, since the movable range of the objective lens is limited, it is not possible to fix the pickup means main body composed of optical components such as a semiconductor laser which is a light source and a photodetector, and to follow the entire surface of the disk with only the objective lens.

Therefore, generally, tracking is performed by using a means for moving the entire pickup means in the radial direction. For example, as one example, there is the one described below.

FIG. 26 is a block diagram of tracking control including radial feed control of the conventional disk device described in Heitaro Nakajima and Hiroshi Ogawa, published by Ohmsha, illustrated compact disk reader p160, FIG. It is a revised version.

In the figure, 1 is a disc, 2 is a pickup means for optically reading information from a recording track of the disc 1, and 3 is a track error detection means for calculating a detection signal from the pickup means 2 to detect a track error. Reference numeral 4 denotes a phase compensation means composed of phase advance means, 5
Is a tracking actuator drive means for driving the tracking actuator built in the pickup means by the output of the phase compensation means 4, 6 is a track error low frequency component detection means for detecting a DC component of the track error signal, and 7 is a disk for the pickup means 2. 1 is a radial feed means having a function of moving in the radial direction, and 8 is a radial feed means drive means for driving the radial feed means 7 by the track error low frequency component signal from the track error low frequency component detection means 6.

Next, the operation, operation, and effect will be described. A conventional tracking device of a disk device inputs a detection signal from a pickup means 2 to a track error detection means 3 to detect a track error. In general, the detected track error is phase-compensated by the phase compensating means 4 composed of phase advance means, and the tracking actuator drive means 5 negatively feeds back to the tracking actuator built in the pickup means 2.
Servo loop is closed. Further, as for the track error signal, the track error low-frequency component detecting means 6 detects the track error low-frequency component signal, and the signal is driven by the radial feeding driving means 8 to the radial feeding means 7 in a negative feedback drive. The servo loop is closed.

Due to the above two servo loops, the pickup means 2 operates at a high speed in a narrow range, and the radial feeding means 7 operates at a low speed, but a large light spot is operated from the innermost track to the outermost track of the disc, and the light spot is always kept. Control is performed so as to be the center of the information track.

[0009]

In the conventional tracking control, the frequency characteristic is poor (the movable part mass is large, the movable part secondary resonance exists in the tracking control band, etc.).
When the inexpensive radial feeding means 7 was used, the control band of the second servo loop could only be set low. In this case, the disk eccentricity will be followed only by the first servo loop. However, in the first servo loop, the movable range of the actuator that moves the objective lens is limited to a small range. In addition, when the push-pull method is used for detecting the track error, an offset proportional to the track error amplitude is generated. is there. Therefore, the track error amplitude range in which the first servo loop can follow (hereinafter referred to as the first loop followable range) is limited to a small range. For example, when the disk eccentricity is larger than the first loop followable range, there are problems that an offset occurs in the track error signal and the control characteristic deteriorates due to an increase in restoring force of a spring that supports the objective lens.
Further, when the radial feeding means 7 having poor frequency characteristics is used, if the control band of the second servo loop is forcibly increased, the stability of the entire tracking control is impaired, oscillation occurs, and signal reproduction becomes impossible. There is a problem such as.

Further, if the radial feeding means 7 having a good frequency characteristic is used, the band of the second servo loop can be increased to follow the disc eccentricity, but there is a problem that the apparatus becomes expensive.

The present invention has been made in order to solve the above-mentioned conventional problems, and a radial feed control method in a disk drive capable of good tracking control even if an inexpensive radial feed means is used. Aim to get.

[0012]

A radial feed control system in a disk apparatus according to the present invention is, in claim 1, a track error low frequency component detecting means 6 of a second servo loop.
Instead of the above, the upper limit level determining means and the lower limit level determining means having a window in the range included in the first loop followable range, an adding means for adding the outputs of the two level determining means, and a rectangular wave of the adding means output A track error correction means composed of amplification means for changing the amplitude is installed.

According to a second aspect of the present invention, in addition to the configuration of the track error correction means 9 of the second servo loop of the first aspect of the invention, the low-pass filter means limits the band of the second servo loop.

According to a third aspect of the present invention, in addition to the structure of the track error correction means 9 of the second servo loop of the first aspect, a low-pass filter means for suppressing the noise of the track error signal is inserted before the track error correction means 9. It is a thing.

According to a fourth aspect, in addition to the configuration of the track error correction means 9 of the second servo loop in the first aspect, a low pass filter for suppressing noise of the track error and a low pass filter for limiting the band of the second servo loop. Are inserted in the front stage and the rear stage of the track error correction means 9, respectively.

According to a fifth aspect, in addition to the structure of the track error correcting means 9 of the second servo loop in the first aspect, a speed detecting means for detecting the speed of the radial feeding means 7 and a DC component of the detected speed are removed. And a DC removal filter means for performing the damping control with a damping group that negatively feeds back the output of the DC removal filter means to the drive signal of the radial feed means 7.

According to a sixth aspect of the present invention, in addition to the structure of the track error correcting means 9 of the second servo loop and the band limiting low pass filter means of the second aspect, a speed detecting means for detecting the speed of the radial feeding means 7, The DC removal filter means for removing the DC component of the detection speed and the damping control for the output of the DC removal filter means by the damping group which negatively feeds back the driving signal of the radial feed means 7 are used.

In addition to the structure of the track error correction means 9 of the second servo loop and the track error signal noise suppression low pass filter, the speed detection means for detecting the speed of the radial feed means 7 is also provided. And the DC removal filter means for removing the DC component of the detected speed, and the damping control by the damping group which negatively feeds back the output of the DC removal filter means to the drive signal of the radial feed means 7.

In addition to the structure of the track error correcting means 9 of the second servo loop, the band limiting low pass filter and the track error signal noise suppressing low pass filter, the speed of the radial feeding means 7 is set. The speed detecting means for detecting, the DC removing filter means for removing the DC component of the detected speed, and the damping control of the output of the DC removing filter means by the damping group which negatively feeds back to the drive signal of the radial feeding means 7 are configured. is there.

According to a ninth aspect of the present invention, the track error correction means 9 according to the first to eighth aspects includes two comparators for respectively discriminating the upper limit level and the lower limit level, and the two comparators.
It is configured by two electric switches that use one comparator output as a control signal, an adder that adds the outputs of the two electric switches, and an amplifier that amplifies the output of the adder.

According to a tenth aspect of the present invention, the method for detecting the speed of the speed detecting means according to the fifth to eighth aspects uses a signal obtained by detecting the back electromotive force of the magnetic circuit for driving the radial feeding means 7 as the speed.

According to an eleventh aspect of the invention, the speed detecting means according to the tenth aspect of the invention is provided with a measured drive current signal of the drive magnetic circuit,
The configuration is such that a differential is obtained from an estimated drive current obtained by inputting a drive voltage to an impedance characteristic equivalent circuit that simulates the impedance characteristic of the drive magnetic circuit.

According to a twelfth aspect of the present invention, the drive current detection in the eleventh aspect is configured to measure the voltage across the current detection resistor inserted between the drive magnetic circuit and the ground.

[0024]

In the feed control method for the disk device according to the present invention, in claim 1, the operating range of the second servo loop is set so that the first loop followable range is in the dead zone, and the normal speed recording is performed. It is possible to increase the apparent control band of the second servo loop without impairing the stability of tracking control during reproduction.

In the second aspect, in addition to the operation of the first aspect, the stability of the radial feed control system is improved by further limiting the signal band of the second servo loop.

In the third aspect, in addition to the operation of the first aspect, the noise is suppressed by the low-pass filter for suppressing the noise of the track error signal, so that the stability of the radial feed control system is improved.

In the fourth aspect, in addition to the operation of the first aspect, the noise of the track error signal is suppressed, and the band of the second servo loop is limited, so that the stability of the radial feed control system is further improved. Improved.

In the fifth aspect, in addition to the operation of the first aspect, the stability of the radial feed control system is improved by performing damping control on the radial feed means 7.

In the sixth aspect, in addition to the operation of the second aspect, the stability of the radial feed control system is improved by performing damping control on the radial feed means 7.

In the seventh aspect, in addition to the operation of the third aspect, the stability of the radial feed control system is improved by performing damping control on the radial feed means 7.

According to the eighth aspect, in addition to the operation of the fourth aspect, the radial feed means 7 is subjected to damping control to improve the stability of the radial feed control system.

In the ninth aspect, when a track error is input, a rectangular wave having an arbitrary amplitude with a threshold level in a predetermined range within the first loop followable range is output.

In the tenth aspect, the counter electromotive force of the magnetic circuit for driving the radial feeding means 7 is detected.

In the eleventh aspect, the drive current and drive voltage of the radial feeding means 7 are calculated, and the counter electromotive force of the radial feeding means 7 is detected.

In the twelfth aspect, the driving current of the radial feeding means 7 is detected by measuring the voltage across the current detecting resistor.

[0036]

【Example】

Example 1. 1 is a block diagram showing a tracking control system in Embodiment 1 of the present invention. In the figure, 10
1 is an upper limit level discriminator, 102 is a lower limit level discriminator, 1
Reference numeral 03 is an adding means, and 104 is an amplifying means.
Reference numeral 04 serves as a substitute for the conventional track error low frequency component detection means 6.

FIG. 2 is a diagram showing the state of signals in the first embodiment of the present invention. In FIG. 2, (a) is a track error signal, (b) is an output signal of the upper limit level discriminating means 101, and FIG.
(C) is an output signal of the lower limit level determination means 102, (d)
Is an output signal of the adding means 103, and (e) is an amplifying means 104.
Is the output signal of.

FIG. 3 is a block diagram showing the configuration of the track error correction means 9, in which 101a and 1a are shown.
Reference numeral 02a is a comparator, and 101b and 102b are switches.

FIG. 4 is a diagram showing the relationship between the objective lens position and the track error sensor offset.

FIG. 5 is a diagram showing the effect of the first embodiment of the present invention.

Next, the operation of the embodiment will be described. In order to detect a track error in an optical disk device, particularly a write-once disk or an erasable disk, a push-pull method is used which has a high light utilization efficiency as the emission power increases. The push-pull method has a problem in that a sensor offset occurs as the objective lens moves. In order to solve this problem, a two-stage coupling method has been developed, which extends the control band of the second servo loop described in the conventional example and can follow the disc eccentricity or the like which becomes a large-amplitude track error signal. However, this requires the use of an expensive mechanism (a linear motor or the like that is designed with high precision and has no secondary resonance within the tracking control band) that has a large driving force and little mechanical resonance.

In the conventional structure, since the first servo loop and the second servo loop are always operated in cooperation with each other, it is relatively difficult to design a stable control system.
Therefore, in the present invention, during stable first loop followable range operation, the tracking error signal is not transmitted to the second servo loop, thereby achieving extremely stable tracking control. Also, the track error signal is the first
When the loop-following range is exceeded, the operation of the second servo loop is simply a switching operation of a predetermined value so that the stability of the entire tracking control system is not affected while ensuring the low-frequency gain. did. The following method is an example of a method for realizing the above matters.

First, the track error correction means 9 which is a feature of the present invention will be described. The track error signal is sent to the upper limit level determination means 101 and the lower limit level determination means 10.
2 and inputs each output by the addition means 103,
The amplifying means 104 is configured to amplify to an arbitrary amplitude.

FIG. 3 shows an example for easily realizing the structure with an electric circuit. The configuration of the upper limit level determination means 101 is composed of a comparator 101a and a switch 101b. Comparator 101a
Then, the track error signal is compared with the upper limit level reference signal VR, and when the track error signal is larger than the upper limit level reference signal, a HIGH signal is output, and when it is smaller, a LOW level signal is output. The switching means 101b is operated by using the output waveform of the comparator 101a as a control signal. The operation of the switch means 101b is, for example, when the comparator output is HIGH, to a predetermined value of V1,
Set to GND when LOW. The value of the upper limit level determination signal VR is the objective lens position range −V0 to be the first loop followable range indicated by the diagonal lines in FIG.
It is set smaller than the absolute value V0 of + V0. That is, it is set such that VR <V0. This upper limit level discriminating means 101
2 shows an example of input / output signals for understanding the operation of FIG. In the figure, (a) is a track error signal. The track error signal in this example exceeds the upper limit level and the lower limit level. In this case, the output of the upper limit level discriminating means 101 ((b) in the figure) becomes the value of V1 only when the track error signal exceeds the upper limit level, and becomes the GND level in other cases.

Similarly, the configuration of the lower limit level discriminating means 102 is the same as that of the upper limit level discriminating means 101.
2a and switch 102b. The comparator 102a compares the track error signal with the lower limit level reference signal -VR, and outputs HIGH when the track error signal is smaller than the lower limit level reference signal, and outputs a LOW level signal when the track error signal is larger than the lower limit level reference signal. This comparator 102
Switch means 1 using the output waveform of a as a control signal
02b is operated. The operation of the switch means 102b is set, for example, to be a predetermined value -V1 when the comparator output is HIGH and to be GND when the output is LOW. The value of the lower limit level determination signal −VR is obtained by multiplying VR already described in the description of the upper limit level determination means 101 by minus. The output of the lower limit level determination means 102 ((c) in the figure) becomes the value of -V1 only when the track error signal exceeds the lower limit level, and becomes the GND level in other cases.

When the outputs of the upper limit level discriminating means 101 and the lower limit level discriminating means 102, that is, (b) and (c) in FIG. 2 are added by the adding means 103, the result is as shown in FIG. That is, when the track error signal is above the upper limit level, it is at V1 level, when it is below the lower limit level, it is at -V1 level, and in other cases, it is GND.
Become a level. Further, the amplification means 104 determines the amplification gain so that the operation of the radial feeding means 7 does not become excessively oscillating (FIG. 2 (e)). As a result, it is possible to adopt a configuration in which the track error signal is not transmitted to the second servo loop during stable first loop followable range operation, resulting in an extremely stable tracking control system.

In addition, when the track error signal is above the upper limit level or below the lower limit level, the operation of the second servo loop is simply a constant voltage operation with an absolute value of V2 to secure a low range gain. However, the configuration is such that the stability of the entire tracking control system is not affected.

The effect of the present invention is shown in FIG. With only the first servo loop, the track error signal exceeds the first loop followable range, but even if the inexpensive radial feed means 7 is used according to the present invention, as shown by the dotted line in the figure, It is possible to realize stable tracking control within the range that can be followed by one loop. The radial feed means 7 of this embodiment is a linear motor, which is not shown. However, the present invention is not limited to this, and the present invention is applicable to any other means as long as radial feeding is possible with the configuration of FIG.

Example 2. The first embodiment can be applied to the case where the radial feeding means 7 is relatively non-vibrating.
In the second embodiment, an example in which the radial feeding means 7 is oscillating, that is, a secondary resonance exists in the low frequency range is shown.

FIG. 6 is a block diagram showing a tracking control system in the second embodiment of the present invention. In the figure, 1
Reference numeral 05 is a low-pass filter means.

FIG. 7 is a diagram showing frequency characteristics of the radial feeding means 7 in the second embodiment of the present invention.

FIG. 8 shows frequency characteristics of the radial feeding means 7 including the low pass filter 105 according to the second embodiment of the present invention.

FIG. 9 is a diagram showing the effect of the second embodiment of the present invention.

Next, the operation of this embodiment will be described.
This is an example of a case where the radial feeding means 7 (here, a linear motor) has a large secondary resonance in the tracking control band. When the frequency characteristic of the radial feeding means 7 has a relatively large secondary resonance as shown in FIG. 7, when the first embodiment is carried out, the radial feeding means 7 induces vibration at the multiple resonance frequency f0, and the dotted line in FIG. As described above, there is a possibility that the range that can be followed by the first loop is exceeded. This is a radial feeding means 7 having a characteristic that it is easy to vibrate at the secondary resonance frequency f0.
Is driven by a rectangular wave control signal (output of the amplifying means 104) containing a lot of high frequency components (of course, f0),
To prevent this, the gain of the component of f0 should be lowered from the control signal of the radial feeding means 7. As a means for realizing this, there is the low-pass filter means 105 in FIG. The low-pass filter means 105 is composed of a low-pass filter whose cutoff frequency is set lower than f0. FIG. 8 shows an example of the operation of the low pass filter 105. FIG. 8 shows the frequency characteristic of the radial feed means 7 including the low-pass filter means 105, and is f0 as compared with the case without the low-pass filter 105 shown by the broken line in the figure.
The gain of is improved and it is difficult to vibrate.

The vibration at the secondary resonance frequency f0 shown by the dotted line in FIG. 9 is improved as shown by the solid line. The radial feed means 7 of this embodiment is a linear motor, which is not shown. However, the present invention is not limited to this, and the present invention can be applied to any other means as long as radial feeding is possible with the configuration of FIG.

Example 3. When the S / N of the track error signal is bad, the output of the track error correction means 9 of the present invention generates a lot of high-frequency whisker-like noises. Therefore, when the radial feed means 7 is driven by this output, abnormal noise is generated. There was a problem.

The present embodiment has been made to solve this problem, and it has been solved by inserting low-pass filter means for removing the noise of the track error signal input to the track error correction means 9.

FIG. 10 is a block diagram showing a tracking control system in the third embodiment of the present invention. In the figure,
Reference numeral 106 is a low-pass filter means.

FIG. 11 is a diagram showing a state of signals in the third embodiment of the present invention. In the figure, (a) is a track error signal, (e) is an output signal of the amplifying means 104, and (f) is a signal.
Is the output signal of the low-pass filter means 106.

FIG. 12 is a block diagram showing the configuration of the low-pass filter means 106 and the track error correction means 9 in the present invention.

Next, the operation of the embodiment will be described. In the present embodiment, the track error correction means 9 is passed through the low pass filter 106 that removes the sensor noise of the track error signal.
To enter. Since other configurations are the same as those of the first embodiment, the description thereof will be omitted.

The cutoff frequency of the low-pass filter means 106 is preferably set higher than the tracking control band in order to avoid the phase rotation of the tracking error signal within the tracking control band as much as possible. In the present embodiment, the cutoff frequency is about 8 kHz. It is set to a second-order low-pass filter that has frequency. Of course, this value changes depending on the applied model and mechanical specifications, and is not limited to this value.

The operation of the low pass filter 106 is shown in FIG. When the track error signal has a poor S / N as shown in (a), whiskers-like noise is generated in the output (e) of the amplifying means 104 in the first embodiment. If the radial feeding means 7 is driven based on this signal, abnormal noise may occur.
Therefore, the track error signal is output to the low pass filter 106.
The input and filtered output is (f). When this filtered waveform is input to the track error correction means 9 instead of the track error signal, the output waveform of the amplification means 104 is S / S as shown in FIG.
N becomes the same as the waveform when a good track error signal is input, and a good tracking operation can be performed without any abnormal noise from the radial feeding means 7.

Example 4. The fourth embodiment shows an embodiment in which the radial feeding means 7 is oscillating, that is, the secondary resonance exists in the low range, and the S / N of the track error signal is bad.

FIG. 13 is a block diagram showing a tracking control system in the fourth embodiment of the present invention. In the figure,
Reference numerals 105 and 106 are low-pass filter means.

FIG. 14 is a block diagram showing the configuration of the low-pass filter means 106 and the track error correction means 9 in the fourth embodiment of the present invention.

Next, the operation of the embodiment will be described. In this embodiment, the radial feed means 7 (here, a linear motor) has a large secondary resonance in the tracking control band, and in addition, the S / N of the track error signal is bad. Such a case can be solved by combining the second and third embodiments of the present invention. The block diagram of this embodiment is as shown in FIG. Thus, the low-pass filter means 106 of the third embodiment is added to the configuration of the second embodiment.
Has been added. The detailed structure is shown in FIG.
Shown in. It should be noted that detailed description of the constituent elements of the present embodiment is omitted because it has already been described in the second and third embodiments.

According to the fourth embodiment of the present invention, the stability of the radial feed control system is further improved, and accordingly the performance of the tracking control system can be improved.

Embodiment 5 In this embodiment, the first loop followable range is remarkably narrower than the disk eccentricity value, and the slide feed means 7 uses a voice coil motor, more specifically, a linear motor having resonance in the tracking control band. This is an example.

FIG. 15 is a block diagram showing a tracking control system in the fifth embodiment of the present invention. In the figure,
Reference numeral 200 is a subtracting means, 201 is a current detecting resistor, 202 is a speed detecting means for detecting the speed of a radial feeding means 7 (for example, a linear motor) having a driving means by a voice coil motor, and 203 is a direct current removing filter for removing direct current components. Means, 204 is an amplification means.

FIG. 16 is a block schematic diagram of a damping control unit according to the fifth embodiment of the present invention.
0 is an impedance characteristic equivalent circuit, 251 is a current detection circuit, 252 is a subtractor, and 250 to 252 constitute the speed detection means 202.

FIG. 17 is a block diagram expressing the damping control unit in the fifth embodiment of the present invention by the control theory.
The linear motor 7 has 260; impedance characteristics, 26
1; linear motor 7 force constant, 262; acceleration / force conversion coefficient, 263; integration block, 264; integration block, 2
65; counter electromotive force coefficient, 266: subtraction block.

FIG. 18 is a block diagram for explaining the configuration of the current detection circuit 251 according to the fifth embodiment of the present invention.

FIG. 19 is a circuit diagram showing an example in which the damping control in the fifth embodiment of the present invention is configured by an actual electric circuit.

FIG. 20 is a diagram showing the effect of the fifth embodiment of the present invention, showing each signal in the control loop. In the figure, (a0); track error signal in the case of only the first servo loop; (e0); track error correction means 9 output in the configuration of the first embodiment under the same conditions as above; (a1); first in the configuration of the first embodiment. Track error signal when the second servo loop is also closed, (a2); Track error signal when the second servo loop in the fifth embodiment is also closed.

FIG. 21 is a frequency characteristic diagram showing the effect of damping control in the fifth embodiment of the present invention.

Next, the operation of the embodiment will be described. Figure 20 (a
When the disk eccentricity amount is significantly larger than the first loop followable range as in 0), the output of the track error correction means 9 having the configuration of the first embodiment has almost no dead zone as in (e0). When the linear motor 7 having the resonance shown by the solid line in FIG. 21 is used, the resonance is excited when driven by a rectangular wave having a large amplitude such as (e0). Explaining the example in the drawing, the spring-mass resonance of the resonance frequency f1 is generated by the movable portion of the linear motor 7 and the above-mentioned spring property due to the spring element such as wiring.

When such a linear motor is used for tracking control with the configuration of the first embodiment under the condition that a disk having a disk eccentricity whose amplitude is larger than the first loop followable range is used, Since the linear motor 7 resonates at the resonance frequency f1 as in 20 (a1), the resonance of the linear motor 7 remains in the track error signal, and the first
Exceeds the loop following range. To prevent this, the resonance of the linear motor 7 may be damped. In order to suppress this resonance, damping control by speed feedback has been conventionally performed. In the conventional configuration, a magnetic circuit for speed detection is provided in the movable portion of the linear motor 7, and feedback control is performed using the output of this magnetic circuit as a speed signal. However, in such a conventional configuration, since a magnetic circuit for speed detection is separately required for damping control, there is a problem that the mechanical configuration becomes complicated and the device becomes expensive.

In this embodiment, a damping control system which does not require the conventional magnetic circuit for speed detection is realized. The damping control will be described below.

In this damping control, as shown in FIG. 15, the detected speed signal is fed back to the tracking control signal of the current detection resistor 201, speed detection means 202, direct current removal filter means 203, amplification means 204, and linear motor 7. And subtraction means 200 for

As shown in FIG. 16, the speed detecting means 202 is composed of an impedance characteristic equivalent circuit 250 of a linear motor drive coil, a current detecting circuit 251, and a subtracting circuit 252 which takes the difference between the outputs of both circuits. .

The configuration of the current detection circuit 251 is as shown in FIG. Resistance value R (Ω) Inductance L
(H) The drive coil of the linear motor 7 is connected to the drive coil in series and the other end is grounded, and the voltage across the current detecting resistor 201 having a resistance value r is measured. This signal is used as the linear motor drive current. Assuming that the linear motor drive voltage is V, the voltage across the linear motor drive coil is V2, the voltage across the current detection resistor 201 is V1, and the current is I,

[0083]

[Equation 1]

It becomes Therefore, to detect the current,
It is understood that it is sufficient to detect V1 or V2. In this embodiment, V1 is detected, and the detected voltage signal is multiplied by 1 / r to detect the current.

Next, the principle of speed detection will be described.
In FIG. 17, the dotted line 7 represents the linear motor 7 in a block diagram. The actual operation of the linear motor 7 can be modeled as follows.
As the drive voltage, a voltage obtained by subtracting a back electromotive force, which will be described later, is converted into a current by the drive coil impedance characteristic 260. The electric current is converted into force by the force constant 261 of the linear motor driving magnetic circuit. The force is the reciprocal 26 of the mass of the moving part of the linear motor.
It becomes acceleration at 2, and is converted to speed at integration block 263. The velocity is converted to a position in integration block 264. The speed is converted into a voltage by the back electromotive force coefficient 265 and is fed back to the drive voltage. This feedback can be expressed in subtraction block 266.

According to the above model, the drive current I includes the drive voltage V and the counter electromotive force proportional to the speed. If you write in the formula,

[0087]

[Equation 2]

It becomes In order to detect the speed, the current value is estimated by an equivalent circuit from the drive voltage signal that does not include the back electromotive force information, and if the differential is taken, the back electromotive force, that is, an information signal proportional to the speed is obtained.

[0089]

[Equation 3]

Next, the DC removing filter 203 will be described. The speed detecting means 202 has a slight error from the impedance characteristic equivalent circuit 250 created by the electric circuit due to temperature drift of the actual drive coil resistance value and the current detection resistance value, variations in parts, and the like. This error becomes an error of the DC component of the detected speed signal. Since the speed originally does not have a DC component, feedback of the speed including this error signal causes position drift of the linear motor 7, which adversely affects the tracking control.

Therefore, in the present invention, the DC removing filter means 203, which functions to correct this error, is inserted in the damping control loop. The frequency characteristic DC (s) of the DC removal filter 203 is

[0092]

[Equation 4]

Therefore, T may be selected as an optimum arbitrary value in accordance with the temperature characteristics of the circuit, but generally it is desirable to have a large value.

Next, the amplification gain GF of the amplification means 204 will be described. This GF is preferably as large as possible, but it is desirable to set it so that the damping control loop does not oscillate. Although an example of damping is shown by a dotted line in FIG. 21, it is desirable to set the gain to completely suppress the peak due to resonance for at least this example.

The damping control of the linear motor 7 is constituted by the above-mentioned constitution. When this is used for tracking control, a track error that was oscillating as shown in (a1) of FIG. 20 is cured within the first loop followable range as shown in (a2), and a stable system is improved. It

FIG. 19 shows an example in which the damping control system is realized by an inexpensive and simple electric circuit. Note that this example is merely an example, and it goes without saying that the same result can be obtained with any other configuration as long as the configuration of the damping group shown in the block diagram of FIG. 15 can be realized.

Example 6. In the present embodiment, the first loop followable range is remarkably narrower than the disc eccentricity value, and the slide feeding means 7 is a voice coil motor, more specifically, a linear motor in which not only the primary resonance but also the secondary resonance exists in the tracking control band. It is an example for the case of using. This is an application of the fifth embodiment to the second embodiment of the present invention.

FIG. 22 is a block diagram showing a tracking control system according to the sixth embodiment of the present invention. In the configuration of the second embodiment of the present invention, the speed detecting means 202, the direct current removing filter means 203 and the amplifying means of the fifth embodiment are added. 204, subtraction means 200
Is added.

FIG. 23 is a diagram showing frequency characteristics of the linear motor 7 according to the sixth embodiment of the present invention. In the figure, the solid line shows the frequency characteristic of the linear motor 7 of this embodiment, and the broken line shows the frequency characteristic of the linear motor 7 after the damping control and filtering of this embodiment.

Next, the operation of the embodiment will be described. In this embodiment, the linear motor 7 has a large primary resonance and a large secondary resonance in the tracking control band. When the frequency characteristic of the linear motor 7 has relatively large primary resonance and multiple resonance as shown in FIG. 23, when the first embodiment is carried out, the linear motor 7 induces vibration by the primary resonance and the multiple resonance, and There is a risk that the loop following range will be exceeded. This is a combined problem of the second and fifth embodiments of the present invention. Therefore, in order to solve this problem, the second and fifth embodiments may be used together as shown in the block diagram of FIG. The respective constituent elements in the figure and the functions thereof are the same as those in the second and fifth embodiments already described, and therefore the description thereof will be omitted.

The effect of the present invention is shown in FIG. Stable tracking control can be realized by improving the frequency characteristic of the linear motor 7 whose resonance characteristic is poor as shown by the solid line as shown by the dotted line.

Embodiment 7 In this embodiment, the first loop followable range is remarkably narrower than the disk eccentricity value, the slide feeding means 7 uses a voice coil motor, more specifically, a linear motor having resonance in the tracking control band, and , S / of track error signal
This is an example for the case where N is bad. This problem is a case where the third and fifth embodiments of the present invention are combined, and the third and fifth embodiments may be used together as shown in the block diagram of FIG.

FIG. 24 is a block diagram showing a tracking control system in the seventh embodiment of the present invention. The constituent elements in the figure and the functions thereof are the same as those of the third embodiment already described.
Also, since it is similar to the fifth embodiment, the description thereof is omitted.

Embodiment 8 In this embodiment, the first loop followable range is remarkably narrower than the disk eccentricity value, and the slide feed means 7 is a voice coil motor, more specifically, a linear resonance having a primary resonance and a secondary resonance within the tracking control band. This is an embodiment for the case where a motor is used and the S / N of the track error signal is bad. This problem occurs when the fourth and fifth embodiments of the present invention are combined, and the fourth and fifth embodiments may be used together as shown in the block diagram of FIG.

FIG. 25 is a block diagram showing a tracking control system in the eighth embodiment of the present invention. The constituent elements in the figure and their functions are the same as those in the fourth embodiment already described.
Also, since it is similar to the fifth embodiment, the description thereof is omitted.

[0106]

As described above, according to the first aspect of the radial feed control method in the disk device of the present invention, even if the inexpensive radial feed means 7 having poor frequency characteristics is used, high performance and stability are achieved. Tracking control can be realized.

According to the second aspect, even when the inexpensive radial feeding means 7 having a poor frequency characteristic existing in a band where the secondary resonance exists is low, high performance and stable tracking control can be realized.

According to the third aspect, it is possible to realize high-performance and stable tracking control even when the inexpensive radial feeding means 7 having poor frequency characteristics is used and the tracking sensor noise is large.

According to the fourth aspect, the inexpensive radial feeding means 7 having a low frequency characteristic in the low band of the secondary resonance is used, and high performance and stable tracking control can be performed even when the tracking sensor noise is large. realizable.

According to the fifth aspect, high-performance and stable tracking control can be realized even when the inexpensive radial feeding means 7 having resonance due to the spring property of wiring or the like and having poor frequency characteristics is used.

According to the sixth aspect, even when the inexpensive radial feed means 7 having resonance due to the spring property of the wiring or the like and existing in a band where the secondary resonance is low and having poor frequency characteristics is used, high performance is obtained. Stable tracking control can be realized.

According to the seventh aspect, the inexpensive radial feed means 7 having resonance due to the spring property of the wiring or the like and having poor frequency characteristics is used, and high performance and stable tracking control can be performed even when the tracking sensor noise is large. realizable.

According to the eighth aspect, the inexpensive radial feeding means 7 having resonance due to the spring property of the wiring or the like and in the band where the secondary resonance is low and having poor frequency characteristics is used, and the tracking sensor noise is reduced. Even if it is large, high performance and stable tracking control can be realized.

According to the ninth aspect, the structure of the track error correction means 9 is composed of two comparators 101a, 102a,
Since it is composed of a simple electric circuit including two switches 101b and 102b, an adder 103, and an amplifier 104,
Track error correction can be realized easily at low cost.

According to the tenth aspect, the radial feeding means 7
The speed is detected by the method of measuring the back electromotive force of the magnetic circuit for driving the radial feeding means 7, so that a high-performance and stable tracking device can be provided inexpensively without the need for a magnetic circuit for speed detection as in the past. realizable.

According to the eleventh aspect, the radial feeding means 7
Since the counter electromotive force is detected by using the simulation circuit of the magnetic circuit, the accurate speed can be detected.

According to the twelfth aspect, since the method of measuring the voltage across the current detection resistor in which the drive current detection is inserted in the drive wiring path is used, the drive current can be detected easily and inexpensively.

[Brief description of drawings]

FIG. 1 is a block diagram showing a tracking control system according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a state of signals in the first embodiment of the present invention.

FIG. 3 is a block diagram showing the configuration of a track error correction means 9 according to the first embodiment of the present invention.

FIG. 4 is a diagram showing a relationship between an objective lens position and a track error sensor offset.

FIG. 5 is a diagram showing an effect of Example 1 of the present invention.

FIG. 6 is a block diagram showing a tracking control system in Embodiment 2 of the present invention.

FIG. 7 is a radial feeding means 7 according to the second embodiment of the present invention.
It is a figure which shows the frequency characteristic of.

FIG. 8 is a low-pass filter 1 according to a second embodiment of the present invention.
It is a frequency characteristic diagram of the radial feeding means 7 including 05.

FIG. 9 is a diagram showing an effect of Example 2 of the present invention.

FIG. 10 is a block diagram showing a tracking control system in Embodiment 3 of the present invention.

FIG. 11 is a diagram showing a state of a signal in Example 3 of the present invention.

FIG. 12 is a block diagram showing the configurations of a low-pass filter means 106 and a track error correction means 9 in Embodiment 3 of the present invention.

FIG. 13 is a block diagram showing a tracking control system in Embodiment 4 of the present invention.

FIG. 14 is a block diagram showing a more detailed configuration of a low-pass filter means 106 and a track error correction means 9 in Embodiment 4 of the present invention.

FIG. 15 is a block diagram showing a tracking control system in Embodiment 5 of the present invention.

FIG. 16 is a block schematic diagram of a damping control unit according to the fifth embodiment of the present invention.

FIG. 17 is a block diagram expressing a damping control unit according to a fifth embodiment of the present invention by a control theory.

FIG. 18 is a current detection circuit 25 according to the fifth embodiment of the present invention.
3 is a block diagram for explaining the configuration of FIG.

FIG. 19 is a circuit diagram showing an example in which damping control in Embodiment 5 of the present invention is configured by an actual electric circuit.

FIG. 20 is a diagram showing an effect in Example 5 of the present invention.

FIG. 21 is a frequency characteristic diagram showing the effect of damping control according to the fifth embodiment of the present invention.

FIG. 22 is a block diagram showing a tracking control system in Embodiment 6 of the present invention.

FIG. 23 is a diagram showing frequency characteristics of the linear motor 7 according to the sixth embodiment of the present invention.

FIG. 24 is a block diagram showing a tracking control system in Embodiment 7 of the present invention.

FIG. 25 is a block diagram showing a tracking control system in Example 8 of the present invention.

FIG. 26 is a block diagram showing a conventional tracking control system.

[Explanation of symbols]

 1 disk 2 pickup means 3 track error detection means 4 phase compensation means 5 tracking actuator drive means 6 track error DC component detection means 7 radial feed means 8 radial feed means drive means 9 track error correction means 101 upper limit level determination means 102 lower limit level determination Means 103 Addition means 104 Amplification means 105, 106 Low-pass filter means 200 Subtraction means 201 Current detection resistor 202 Speed detection means 203 DC removal filter means 204 Amplification means 250 Impedance characteristic equivalent circuit 251 Current detection circuit 252 Subtraction circuit 260 Linear motor drive coil Impedance characteristics 261 Force constant 262 Reciprocal number of moving part mass 263, 264 Integration block 265 Back electromotive force constant 266 Subtraction block

Claims (12)

[Claims] 1. A signal from a spirally formed information track on a disk-shaped medium is detected by a pick-up means constituted by an optical or electrostatic capacitance type signal detection, and a track error signal is detected from the detected signal. In the device for controlling the radial feed means equipped with the pickup means by the control signal based on the track error signal, the track error correction means for inputting the track error signal and generating the control signal is configured as described above. When the track error signal is within a predetermined area within the correctable range of the pickup means, the ground (ground) is prevented so that the track error is not transmitted to the radial feeding means, and when the track error signal exceeds the predetermined range, a fixed predetermined value is provided. Radial feed in a disk drive characterized in that the value is transmitted to a radial feed means control method. 2. A track error signal is detected from the information signal formed in a spiral shape on a disk-shaped medium by a pickup means constituted by an optical type or an electrostatic capacitance type for signal detection, and from the detection signal. In the device for controlling the radial feed means equipped with the pickup means by the control signal based on the track error signal, the track error correction means for inputting the track error signal and generating the control signal is configured as described above. When the track error signal is within a predetermined area within the correctable range of the pickup means, GND is set so that the track error is not transmitted to the radial feed means, and when it exceeds the predetermined range, a predetermined predetermined value is set. A low-pass filter that limits the band of the output waveform of the track error correction means so that it is transmitted to the radial feed means. A radial feed control method in a disk device, characterized in that the radial feed means is supplied to the radial feed means via a filter. 3. A signal from a spirally formed information track on a disk-shaped medium is detected by a pickup means composed of an optical type or an electrostatic capacitance type, and a track error signal is detected from the detected signal. In a device for controlling the radial feed means equipped with the pickup means by a control signal based on the track error signal, the track error signal is input through a low-pass filter for removing a noise component to generate a control signal. The configuration of the track error correction means is set to GND so that the track error is not transmitted to the radial feed means when the track error signal is within a predetermined area within the correctable range of the pickup means, and the predetermined range is set. When it exceeds, it is configured to transmit a certain predetermined value to the radial feeding means. Radial feed control method for disk drive. 4. A track error signal is detected from the detection signal by detecting the signal from a spirally formed information track on a disk-shaped medium by a pickup means constituted by an optical type or an electrostatic capacitance type. In a device for controlling the radial feed means equipped with the pickup means by a control signal based on the track error signal, the track error signal is input through a low-pass filter for removing a noise component to generate a control signal. The configuration of the track error correction means is set to GND so that the track error is not transmitted to the radial feed means when the track error signal is within a predetermined area within the correctable range of the pickup means, and the predetermined range is set. If it exceeds, a certain predetermined value is transmitted to the radial feeding means, A radial feed control system in a disk drive characterized in that the error correction means supplies the signal to the radial feed means via a low-pass filter that limits the band of the output waveform. 5. A signal from a spirally formed information track on a disk-shaped medium is detected by a pick-up means composed of an optical or capacitance type signal detection, and a track error signal is detected from the detected signal. In the device for controlling the radial feed means equipped with the pickup means by the control signal based on the track error signal, the track error correction means for inputting the track error signal and generating the control signal is configured as described above. When the track error signal is within a predetermined area within the correctable range of the pickup means, GND is set so that the track error is not transmitted to the radial feed means, and when it exceeds the predetermined range, a predetermined predetermined value is set. It is configured to transmit to the radial feeding means, and a speed detecting means for detecting the speed of the radial feeding means. A radial feed control method in a disk device, comprising: a damper group which is installed and feeds back a detected speed signal of the speed detection means to a radial feed means control signal through a filter for removing a DC component. 6. A signal from a spirally formed information track on a disk-shaped medium is detected by a pick-up means constituted by an optical type or an electrostatic capacitance type, and a track error signal is detected from the detected signal. In the device for controlling the radial feed means equipped with the pickup means by the control signal based on the track error signal, the track error correction means for inputting the track error signal and generating the control signal is configured as described above. When the track error signal is within a predetermined area within the correctable range of the pickup means, GND is set so that the track error is not transmitted to the radial feed means, and when it exceeds the predetermined range, a predetermined predetermined value is set. A low-pass filter that limits the band of the output waveform of the track error correction means so that it is transmitted to the radial feed means. Is supplied to the radial feed means via a filter, and further, a speed detection means for detecting the speed of the radial feed means is installed, and a detection speed signal of the speed detection means is passed through a filter for removing a DC component. A radial feed control method in a disk device, comprising: a radial feed means control signal feedback damper group. 7. A signal from a spirally formed information track on a disk-shaped medium is detected by a pick-up means constituted by an optical type or an electrostatic capacitance type, and a track error signal is detected from the detected signal. In a device for controlling the radial feed means equipped with the pickup means by a control signal based on the track error signal, the track error signal is input through a low-pass filter for removing a noise component to generate a control signal. The configuration of the track error correction means is set to GND so that the track error is not transmitted to the radial feed means when the track error signal is within a predetermined area within the correctable range of the pickup means, and the predetermined range is set. If it exceeds, it is configured to transmit a certain predetermined value to the radial feed means. A speed detecting means for detecting the speed of the radial feeding means is installed, and a damping pin group for feeding back the detected speed signal of the speed detecting means to the radial feeding means control signal through a filter for removing a DC component is characterized. Radial feed control method for disk drive. 8. A signal from a spirally formed information track on a disk-shaped medium is detected by a pickup means constituted by an optical type or an electrostatic capacitance type, and a track error signal is detected from the detected signal. In a device for controlling the radial feed means equipped with the pickup means by a control signal based on the track error signal, the track error signal is input through a low-pass filter for removing a noise component to generate a control signal. The configuration of the track error correction means is set to GND so that the track error is not transmitted to the radial feed means when the track error signal is within a predetermined area within the correctable range of the pickup means, and the predetermined range is set. If it exceeds, a certain predetermined value is transmitted to the radial feeding means, The error correction means is configured to supply to the radial feed means through a low-pass filter that limits the band of the output waveform, and further, the speed detection means for detecting the speed of the radial feed means is installed, and the detected speed signal of the speed detection means. And a damping group for feeding back to the radial feeding means control signal through a filter for removing a DC component, the radial feeding control method in the disk device. 9. The structure of the track error correction means is:
The two comparators for respectively discriminating the upper limit level and the lower limit level of the predetermined range, two electric switches using the two comparator outputs as control signals, an adder for adding the two electric switch outputs, and the adder output are 9. A radial feed control system in a disk device according to claim 1, comprising an amplifier for amplifying. 10. The radial feed control method in a disk drive according to claim 5, wherein the speed detecting means is configured to detect a back electromotive force of a drive magnetic circuit of the radial feeding means. 11. The structure of the speed detecting means comprises an estimated drive obtained by inputting a drive voltage to an actually measured drive current signal of the drive magnetic circuit and an impedance characteristic equivalent circuit simulating the impedance characteristic of the drive magnetic circuit. 11. The radial feed control method for a disk drive according to claim 10, wherein the differential with respect to the current signal is adopted. 12. The drive current detection is performed by measuring a voltage across a current detection resistor inserted between the drive magnetic circuit and ground.
Radial feed control method in the described disk device.