JP3352178B2 - Information recording / reproducing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information recording / reproducing apparatus for recording / reproducing information using an information recording medium such as a magnetic disk and an optical disk, and more particularly to a speed control apparatus for seeking a recording / reproducing head.

[0002]

2. Description of the Related Art Conventionally, in an information recording / reproducing apparatus, in order to record or reproduce information at a target position on a recording medium, it is necessary to move the recording / reproducing head to the target position. In the seek operation, it is necessary to efficiently control the speed of the head and move the head quickly and accurately to a target position. Generally,
As such a speed control method of the recording / reproducing head, there is a method in which an operation schedule (speed profile) up to a target position of the head is determined in advance, and the speed during the operation of the head is detected to control the head along the operation schedule. Has been adopted. Figure 12 is a graph showing the typical control scheme, V _ref is the reference speed, V _n representing the service schedule speed is a speed which is detected during the seek. Here, the relationship between the speed profile and the applied current of a coarse actuator (linear motor) for driving the carriage for moving the head is shown.
The reference speed _Vref is a speed calculated according to the residual distance to the target, and is obtained by the following equation.

V _ref = [2 · α (S−λ / 2 · N)] ^1/2 (1) where S is the moving distance to the target, λ is the track pitch,
α is the deceleration, N is the zero-cross count value, and the movement distance can be determined from the count value. To control the speed of the head, the current command value from the speed V _n to the linear motor at the time the target speed V _ref is calculated for every predetermined period, feedback thereby as the speed of the head follows the target speed Is applied. The command value _Act to the linear motor is calculated by the following equation. Here, K is a feedback gain.

By [0004] _{A ct = K (V ref -V} n) ... (2) above, the linear motor at the beginning, as shown in FIG. 12, the acceleration current is supplied, the speed of the head will be accelerated, the target When the speed reaches the speed, the current of the linear motor changes to a deceleration current, and thereafter, the speed is reduced according to the target speed.
When the vehicle reaches the target position, the speed becomes 0, and the seek operation ends.

[0005] Here, when detecting the speed of the recording / reproducing head, a detection method is selectively used in a high speed range and a low speed range. Specifically, first, in a high-speed region, a track counting method for detecting a speed from the number N of tracks crossed by a head within a predetermined sampling interval T _S is used. The speed by the track count method is calculated by the following equation.

V _n = (λ / 2 · N) / T _s (3) On the other hand, in a low-speed range, the zero-cross point of the tracking error signal is detected, and the speed is detected from the time _Td between the zero-cross points. A counting method is used.
That is, the distance between the zero-cross points is 1 / the track pitch λ.
2, the speed can be detected if the passing time of the half pitch is known. Speed V at this time
_n is obtained by the following equation.

V _n = (λ / 2) / T _d (4) These two speed detection methods are selected according to a predetermined reference speed, and when the head speed is higher than the reference speed value. Is a track count system corresponding to the high-speed range,
When the speed becomes slower than the reference speed value, switching is made to the inter-track counting method corresponding to the low speed range.

[0008]

In the prior art, for example, when a light beam in optical recording is accessed at a target position, the recording / reproducing head is moved by driving the coarse actuator as described above. In order to access the target track by the beam, the objective lens in the head is further moved by the fine actuator to access the target track accurately.
The coarse actuator here refers to a linear motor that roughly moves the head to near the target position, and generally employs a so-called two-stage actuator configuration including such a coarse actuator and a fine actuator. However, when such a two-stage actuator is used, the dense actuator is mounted on the linear motor, and the linear motor itself is relatively heavy, so that when the linear motor starts or stops. The dense actuator will vibrate. Therefore, the detected relative speed of the head fluctuates, which hinders the speed control of the coarse actuator, and in the worst case, the speed control loop oscillates.

Further, this problem will be described in detail with reference to FIG. FIG. 13A is a diagram showing the relationship between the target speed and the detected speed, and shows the detected speed when there is vibration of the fine actuator and the detected speed when there is no vibration. FIG. 13 (b)
FIG. 13A is a diagram showing the drive current of the linear motor corresponding to the speed of FIG. 13A, and FIG. 13C is a diagram showing the position of the objective lens by the fine actuator. When there is no vibration of the fine actuator, the speed of the head follows the target speed as shown in FIG. 13A, and a good seek operation is performed. However, when vibration occurs in the dense actuator due to disturbance such as a stop of the linear motor at the point S in the drawing, a vibration component is applied to the head, and the objective lens is in a state of being vibrated as shown in FIG. Becomes The movement of the objective lens due to this vibration directly affects the detection of the relative speed between the head and the recording medium surface, and as shown in FIG.
B and C have a velocity including a vibration component. When the dense actuator vibrates in this manner, the speed generated by the lens vibration is detected instead of the true speed of the head. At this time, the speed control system attempts to follow the target speed, and the speed control is unstable. In the worst case, there is a problem that the speed control loop oscillates.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and an object of the present invention is to correct information speed fluctuation caused by vibration of a fine actuator to perform a stable seek operation. It is to provide a device.

[0011]

SUMMARY OF THE INVENTION An object of the present invention is to provide an optical
First moving means for coarsely seeking the track in a direction transverse to the track of the information recording medium, and after this coarse seek, a light beam
The objective lens in the head to move the
And second moving means for moving the lens, and means for detecting a seek speed of the objective lens, and means for calculating the seek speed of the target according to the residual distance to the target position, being the detection An information recording / reproducing apparatus having control means for performing speed control at the time of coarse seek of the first moving means based on the set seek speed and the target seek speed ,
Phase between the objective lens and the head during a coarse seek
Means for detecting an opposing movement displacement or movement speed, and correcting the detection value of the seek speed detection means based on the detection value of the movement displacement or movement speed detection means ,
This is achieved by an information recording / reproducing apparatus characterized in that a correction means for removing a variation in seek speed during coarse seek due to vibration of an objective lens is provided.

[0012]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of the information recording / reproducing apparatus of the present invention. Here, an optical disk recording / reproducing apparatus using an optical disk as a recording medium will be described as an example. In FIG. 1, reference numeral 1 denotes an optical disk as an information recording medium, which rotates at a constant speed by driving a drive system (not shown). Reference numeral 2 denotes an optical system for optically recording information on the optical disk 1 or reproducing information recorded on the optical disk 1. The optical system 2 includes a semiconductor laser as a light source for recording / reproducing, an objective lens for narrowing a laser beam of the semiconductor laser to a small light spot, and irradiating the optical disk 1 with a sensor, and a sensor for detecting reflected light from the optical disk 1. And other various optical elements. Reference numeral 12 denotes a tracking actuator for moving the objective lens in the optical system 2 in the radial direction of the optical disc 1, and reference numeral 13 denotes a focus actuator for moving the objective lens in a direction perpendicular to the surface of the optical disc 1. These two actuators 12 and 13 and the optical system 2
Are integrated as an optical head and are configured to be movable in the radial direction of the optical disc 1. Reference numeral 14 denotes a linear motor for moving the optical head in the radial direction of the optical disc 1, and reference numeral 10 denotes a driver for driving the linear motor 14.

Reference numeral 3 denotes a tracking error detector for detecting a tracking error signal based on the output of a sensor in the optical system 2, and reference numeral 4 similarly denotes a focus error detector for detecting a focus error signal based on the sensor output. , 1
Reference numeral 5 denotes a lens position detector for detecting the lens position of the focusing objective lens in the radial direction. Each of the error signal and the lens position signal detected by each of these detectors is converted into a digital signal by the A / D converter 5, and then sent to the digital signal processing unit 6.

A digital signal processing unit 6 is a digital control unit serving as a main control unit of the optical disk recording / reproducing apparatus, an I / O control unit 7 for controlling input / output of signals, and an operation required for control according to a predetermined control program. It comprises a digital signal processor (hereinafter abbreviated as DSP) 8 for executing processing and a memory 9 for storing various data. The digital signal processing unit 6 controls the tracking and focusing of the light beam by controlling the tracking actuator 12 and the focus actuator 13 described above, controls the seek operation for moving the optical head to the designated position, and moves to the designated position. The recording and reproduction of the entire device is controlled by controlling the recording and reproduction of the information. Numeral 11 converts the digital command value calculated by the DSP 8 into an analog value at the time of tracking control, focusing control, or seek control of the optical head, and converts the digital command value into an analog value.
3 and a D / A converter for outputting to the driver 10.

Next, the operation of the above embodiment will be described with reference to FIGS. FIG. 2 is a diagram showing signals of various parts during a seek operation of the optical head, and FIG. 2A shows a speed profile (scheduled operation speed curve to a target position) during a seek and a speed signal actually detected. FIG. Here, two speed signals are shown as the speed signal when the tracking actuator 12 is vibrated and when there is no vibration. 2 (b) shows the drive current of the linear motor 14 during a seek operation, FIG. 2 (c) shows the objective lens position detected by the lens position detector 15, and FIG. 2 (d) shows the lens position detector 1
The speed of the objective lens obtained by the DSP 8 based on the detection value of No. 5. FIG. 3 shows the DSP 8 when the optical head seeks.
FIG. 5 is a flowchart showing the flow of the processing of FIG. 5 and showing an interrupt routine of speed control executed at a cycle of 4 KHz.

First, when a recording or reproducing command is issued from an external control device (not shown) and a recording / reproducing position of the optical disk 1 is designated, the digital signal processing section 6 leaves the current position and the target position of the optical head. The control of the seek operation to the target position is started by obtaining the difference distance. In the speed control during the seek operation, the DSP 8 detects the speed of the optical head as described above, and calculates a command value to the linear motor 14 at regular intervals based on the obtained speed and the target speed. Execute the speed control of the optical head. More specifically, as shown in FIG. 3, the DSP 8 inputs a track count value, which is the number of tracks that the information track of the optical disk 1 has traversed by the light beam from a counter (not shown) (S1). calculate the velocity V _n and the target speed V _ref (S2).
Velocity V _n current track counting method and the inter-track counting method is used according to the low speed range and high speed range, as described above. Also, DSP 8 is the but of calculating the target speed V _ref by the above-described on the basis of the track count value (1), for example a track count value is assumed to be N _2, the target speed V _ref is determined by the following equation Can be
Here, S is the total number of jumps to the target track.

V _ref = [2 · α (S−N ₂ ) · λ / 2] ^1/2 (5) Next, the DSP 8 corrects the detection speed in S3 to S6, that is, the fluctuation of the detection speed due to the vibration of the actuator. The minute is corrected, and a command value to the linear motor 14 is calculated using the obtained correction value (S7). The command value is calculated by the above-described equation (2) and is converted to an analog value by the D / A converter 11, and then is given to the driver 10, and is supplied to the linear motor 14
Is driven. The detection speed correction process will be described later in detail. In this way, the DSP 8 repeatedly executes the series of processes of S1 to S8 described above. As a result, an acceleration current is supplied to the linear motor 14 as shown in FIG. 2B, and the speed of the optical head becomes as shown in FIG. It accelerates toward the target speed as shown. Then, when the speed reaches the target speed, the current of the linear motor 14 changes to a deceleration current, and the speed of the optical head decelerates while following the target speed.

Here, it is assumed that vibration occurs in the tracking actuator 12 due to some disturbance at the point A in FIG. Due to this vibration, the objective lens provided in the optical system 2 is not fixed at the center as shown in FIG. The DSP 8 corrects the detection speed due to vibration in the above-described series of control processes. Specifically, after calculating the current speed and the target speed, the DSP 8 takes in the output of the lens position detector 15 (S3), and calculates the lens speed based on the lens position (S4). This can be obtained as the difference between the previously captured lens position and the currently captured lens position. Then, DSP 8 multiplies the correction gain of the detected speed by the lens speed obtained value (S5), corrects the detected velocity V _n by a lens speed V _L (S6). Modified velocity V _n 'is determined by the following equation. Here, k is a correction gain, which is an arbitrary constant.

[0019] _{V n '= V n -k ·} V L ... (6) thus DSP8 corrects the detected speed, obtained correction value V _n' and calculates a command value of the linear motor 14 by using (S
7) Output to the driver 10 (S8). For example, at the point _A , the detection speed becomes V _A due to the vibration of the actuator, and at the point B, the detection speed becomes V _{B. As} shown in FIG.
The correction speed is calculated by subtracting the lens speeds a and b at the points B and B, respectively. Therefore, the correction speed obtained here is an accurate relative speed between the optical head from which the vibration component of the objective lens has been removed and the disk surface. At point D in FIG. 2A, the DSP 8 switches the optical head speed detection method from the track counting method to the inter-track counting method, and when the number of tracks remaining until the target reaches several tens, for example,
At this time, the control is switched from the coarse seek control of the optical head by the linear motor 14 to the fine seek control of the light beam by the tracking actuator 12. When the light beam reaches the target track, the light beam is finally drawn into the target track, and information is recorded or information is reproduced on the target track.

As described above, in this embodiment, the speed of the lens due to the vibration of the actuator is detected based on the output of the lens position detector for detecting the position of the objective lens, and the lens speed is subtracted from the detected current speed. Thus, the vibration component of the actuator can be removed, and the speed can be corrected to an accurate speed. That is, when vibration occurs in the actuator, as shown in FIG. 2A, the detection speed is detected to include a vibration component such as V _A or V _B. By removing such a vibration component, It is possible to detect an accurate speed. Therefore, even if the actuator vibrates, the current generated by the vibration of the actuator as shown by the broken line in FIG. 2B is eliminated, so that stable speed control can be performed without causing speed control disturbance. Can be.

FIG. 4 is a block diagram showing another embodiment of the present invention. Although the speed of the objective lens is detected based on the output of the lens position detector in the embodiment of FIG. 1, this embodiment is an example in which the lens speed is detected from the angular speed of the objective lens. In FIG. 4, reference numeral 16 denotes a lens angular velocity detector for detecting the angular velocity of the objective lens provided in the optical system 2 in the rotation direction. The angular velocity detected by the lens angular velocity detector 16 is taken into the DSP 8 in the digital signal processing unit 6 and used for correcting the speed of the optical head as described later in detail. Other configurations are the same as those in FIG.

FIG. 5 is a diagram showing signals at various parts in FIG. 4. FIG. 5A shows the target speed and the detected speed of the optical head, and FIG.
5C shows the drive current of the linear motor, and FIG. 5C shows the output of the lens angular velocity detector 16. FIG. 6 is a flowchart showing the flow of the speed control process at the time of seeking of the optical head according to the present embodiment, which is a speed control routine executed at a period of 4 KHz. Since the basic speed control operation is the same as that of the embodiment of FIG. 1, the detailed description is omitted, and here, the operation of correcting the seek speed based on the lens angular speed will be described. First, in FIG. 6, after the current speed and the target speed are detected, the DSP 8 takes in the output of the lens angular velocity detector 16 (S3), and calculates the lens speed based on the output (S4). In other words, by obtaining the moving speed of the objective lens in the radial direction from the rotational angular speed of the objective lens, the fluctuation of the detection speed caused by disturbance is obtained.
The lens speed _VL is obtained by the following equation.

V _L = X · L [m / sec] (7) where X is the angular velocity [rad / s], and L is the distance [m] between the lens rotation center and the lens position.

[0024] Then, DSP 8 multiplies the correction gain k to the lens speed obtained (S5), it corrects the detected velocity V _n by a lens speed (S6). Modified velocity V _n 'is determined by the aforementioned equation (6). For example, FIG.
At point B, the detection speed is V _B due to the vibration of the actuator.
However, since the rotational angular velocity of the lens at point B is b as shown in FIG. 5C, the correction velocity V _n ′ at point B is V _n − (V _B −k · b L) The DSP 8 calculates a command value using the obtained correction speed (S7) and outputs the command value to the driver 10 (S8). Therefore, in this embodiment, the detection speed is corrected based on the lens angular velocity every time the speed is detected, and the speed of the optical head is controlled by the speed signal from which the influence of the vibration is removed. Similarly, even if vibration occurs in the actuator, control is not disturbed, and stable seek control can be performed.

Here, in the above-described embodiment, the detection performance of the lens position is equivalent to the detection performance of the speed signal.
Although important in accurately correcting the detection speed, it can be generally said that the detection performance of the lens position is worse than the detection performance of the speed signal. Further, when the seek control is performed digitally, the influence of the quantization error is large, and the seek control may be disturbed. Hereinafter, such a problem will be described with reference to FIG.

FIG. 7A shows the quantized objective lens position, and FIG. 7B shows the lens moving speed determined from the lens position shown in FIG. 7A. When the lens is moving at a speed of about p as shown by a broken line A in FIG. 7A, the influence of electric noise, quantization noise, or disturbance at a high frequency other than vibration due to the carriage causes A step-like lens position as shown by A 'is obtained. Also, when the lens moving speed is obtained from this lens position, it becomes a speed signal vibrating up and down around the actual lens moving speed B as indicated by B 'in FIG. 7B. Therefore, an embodiment that solves the above-described problems will be described.

This embodiment is similar to the lens position detector 15 shown in FIG.
Then, the average of the lens position detected last time and the current lens position is averaged to correct the lens speed. Further, this embodiment is an optical disc 1 shown in FIG.
In order to correct the lens speed more accurately, the influence of the eccentricity is also removed.

FIGS. 8A and 8B are diagrams showing signals of various parts during a seek operation of the optical head according to the present embodiment. FIG. 8A shows a speed profile (scheduled operation speed curve to a target position) and a speed profile at the time of a seek. FIG. 5 is a diagram illustrating a detected speed signal. Here, the tracking actuator 1 is used as the speed signal.
2 shows two speed signals when vibration occurs and when there is no vibration. FIG. 8B shows a drive current of the linear motor 14 at the time of seeking, and FIG. 8C shows a lens position detector 15.
Is the position of the objective lens detected. When the optical disc 1 is rotated at a constant rotation cycle, eccentricity occurs due to a shift between the center of the optical disc 1 and the center of rotation, and such eccentricity affects the relative positional relationship between the optical head and the optical disc 1. For example, even when the linear motor 14 operates at a constant speed and the tracking actuator 12 is fixed at the mechanical center, the relative speed between the optical head and the disk surface does not become a constant value, and the speed deviation of a certain period caused by eccentricity. It starts to wave. The lens position shown in FIG. 8C undulates at a constant cycle due to the influence of the eccentricity. FIG. 8 (d)
8 shows the lens position after the eccentricity is removed, and FIG.
This is the lens speed obtained from the lens position of (d).

FIG. 9 is a flowchart showing the flow of the processing of the DSP 8 at the time of optical head seeking in this embodiment. The processing in FIG. 9 is a flowchart showing an interrupt routine in which interrupt processing is performed at a frequency of, for example, 4 kHz. In FIG. 9, first, a recording or reproduction command is issued from an external control device (not shown), and a recording / reproduction position of the optical disk 1 is designated. Then, the digital signal processing unit 6 determines a current position and a target position of the optical head. The control of the seek operation to the target position is started by obtaining the residual distance. In the speed control during the seek operation, the DSP 8 detects the speed of the optical head as described above, and calculates a command value to the linear motor 14 at regular intervals based on the obtained speed and the target speed. Execute the speed control of the optical head. Specifically,
DSP8 the light beam from a counter (not illustrated) to enter the track count value is the number of tracks across the information track of the optical disk 1 (S1), calculates based on the current velocity V _n and the target speed V _ref of the optical head so (S2).
Velocity V _n current track counting method and the inter-track counting method is used according to the low speed range and high speed range, as described above.

Next, the DSP 8 takes in the eccentricity data at the present time from the rotation cycle of the spindle motor (not shown) for driving the optical disc 1 to rotate (S3) and stores it in the memory 9. This eccentricity data may be equivalent to one rotation of the spindle motor, and its resolution may be set arbitrarily according to the use accuracy. When the capture of the eccentricity data is completed, the DSP 8 captures the current lens position detected by the lens position detector 15 (S4), and subtracts the eccentricity data stored in the memory 9 from the obtained lens position to obtain the lens by eccentricity. The displacement is removed, and only the fluctuation component of the lens due to the vibration is extracted (S5). Therefore, the components obtained here are shown in FIG.
As shown in (d), the lens position is free from the effect of eccentricity.

That is, in order to effectively remove the influence of the eccentricity, the displacement of the lens position of the tracking actuator 12 due to the eccentricity is measured in advance, and the displacement of the lens position due to the eccentricity during the seek operation is determined by the rotation cycle of the spindle motor. This is given to the tracking actuator 12 in synchronization. Therefore, the periodic speed deviation synchronized with the rotation cycle of the spindle motor due to the eccentricity is removed by driving the lens eccentrically by the tracking actuator 12, and the speed control of the linear motor 14 is not affected. Here, the linear motor 1
If there is a speed control band of 4, the tracking actuator 12 may be fixed at the mechanical center, and the linear motor 14 may follow the speed displacement caused by the eccentricity.

When the removal of the eccentricity is completed, the DSP 8 calculates the lens speed based on the obtained lens position. This is obtained as the difference between the lens position obtained last time and the current lens position (S6). That is, the previous lens position is stored in the memory 9, and when a lens position obtained by removing the current eccentricity is obtained, the lens speed is obtained by subtracting the previous lens position from the current lens position (S6). The obtained lens speed is stored in the memory 9. Next, the obtained lens speed and the previous lens speed stored in the memory 9 are added, and the obtained added value is divided by 2 to perform averaging, thereby calculating a corrected lens speed. Is performed (S7). However, the previous lens speed at this time was not obtained by averaging,
This is the lens speed obtained in the previous S6. In this way, the influence of the quantization error as described above is removed, which will be described later in detail.

[0033] Then, as corrected by the correction lens speed LP_V the current velocity V _n detected previously in DSP 8 (S8). Modified velocity V _n 'is determined by the following equation.
Here, k is a correction gain and is an arbitrary constant.

V _n ′ = V _n −k (correction lens speed: LP_V) (8) After calculating the correction speed V _n , the DSP 8 calculates a command value to the linear motor 14 using the obtained correction value. Do (S
9). This command value is calculated by the above-described equation (2), is converted to an analog value by the D / A converter 11, and then is given to the driver 10 to drive the linear motor 14 (S10). Thus, a series of control operations of the DSP 8 are completed, and the same processing is executed again in the next control cycle. Thus, the DSP 8 repeats the same control at a cycle of, for example, 4 KHz. As a result, an acceleration current is supplied to the linear motor 14 as shown in FIG.
As shown in (a), the vehicle is accelerated toward the target speed.
When the target speed is reached, the linear motor 1
The current of No. 4 changes to a deceleration current, and the speed of the optical head decelerates while following the target speed.

Here, it is assumed that vibration occurs in the tracking actuator 12 due to some disturbance at the point A in FIG. Due to this vibration, the objective lens provided in the optical system 2 is not fixed at the center as shown in FIG. Also, due to this vibration, the detection speed is detected including a vibration component such as V _A at point _A and V B at point _{B. In} the embodiment described with reference to FIGS. As shown in e), the detection speed is corrected by subtracting the lens speeds a and b at the points A and B, respectively. Therefore, it is affected by the quantization error as described above,
As shown in FIG. 7B, the lens speed becomes a speed signal as if it vibrated up and down with respect to the actual lens speed.

On the other hand, in the present embodiment, the speed of the objective lens is corrected by taking the average of the previous lens speed and the current lens speed, and as shown in FIG. v ₁ , if the current lens speed is v ₂ , the addition average value is v ₂ ′, and if the previous lens speed is v ₂ , this time v ₃ , the addition average value is v ₃ ′, and the addition is The value obtained by the average value is an intermediate value between the previous and current lens moving speeds. Accordingly, as shown in FIG. 7 (b), the speed signal C obtained by averaging is much closer to the actual lens moving speed B than in the embodiment described with reference to FIGS. A more accurate lens movement speed can be obtained. Therefore, by correcting the speed of the optical head using the corrected lens speed obtained by the averaging as described above, the seek speed of the optical head can be more accurately corrected.

Further, in this case, the lens position originally includes the eccentricity as shown in FIG.
Since the actuator is driven eccentrically as described above, the eccentricity of the lens position is also removed as shown in FIG. 8D, and the obtained relative speed becomes a more accurate speed. At point D in FIG. 8A, the DSP 8 switches the detection method of the optical head speed from the track counting method to the inter-track counting method, and when the number of remaining tracks to the target becomes, for example, about several tens, the linear motor 14 From the coarse seek control of the optical head by the tracking actuator 12 to the fine seek control of the optical beam by the tracking actuator 12. When the light beam reaches the target track, the light beam is finally pulled in, and information is recorded or information is reproduced on the target track.

As described above, in this embodiment, the effect of the quantization error as described above is removed by calculating the lens speed due to the vibration of the actuator by the averaging of the previous and current speeds. Can be obtained, and the speed of the optical head can be corrected more accurately. In addition, by measuring the displacement of the lens due to the eccentricity of the optical disk and applying it to the actuator in synchronization with the disk rotation cycle, the head speed can be accurately corrected regardless of the vibration of the actuator due to disturbance and the eccentricity of the optical disk. Can be. Therefore, since accurate speed can be detected irrespective of disturbance or eccentricity, current oscillation as shown by a broken line in FIG. 8B is eliminated, and stable speed control can be performed without disturbance of speed control. it can.

Next, another embodiment for removing the influence of the quantization error will be described. FIG. 10 is a flowchart showing the flow of processing of the DSP 8 at the time of optical head seeking in this embodiment. The processing from S1 to S6 in FIG. 10 is the same as that in FIG. In FIG. 10, when the lens speed is calculated by adding and averaging the previous lens speed and the current lens speed (S6), a low-pass component is extracted from the obtained lens speed by a primary low-pass filter (S7). . As the low-pass filter, for example, can be easily configured by a filter having a transfer characteristic such as H (S) = 1 / ( 1 + T S × S) ... (9). Here, T _S is an arbitrary constant.

Here, the process of extracting the low-frequency component of the lens speed by the low-pass filter will be described with reference to FIG. 11. First, A in FIG.
A 'is a lens position detected by the lens position detector 15. As described above, the lens position becomes a step-like lens position due to the influence of electric noise, quantization noise, or disturbance at a high frequency other than vibration due to the carriage. When the moving speed of the lens is obtained from this lens position, a speed signal is generated as if the lens moved upward or downward with respect to the actual moving speed of the lens as indicated by B 'in FIG. 11B. When the moving speed of the lens indicated by B ′ is passed through a low-pass filter to extract low-frequency components,
(B) A speed signal as shown by C can be obtained.
That is, by integrating the rectangular wave-shaped speed signal obtained in S6 through a low-pass filter, C
As shown by, a lens moving speed closer to the actual lens moving speed B can be obtained.

When the low-frequency component is extracted, the current speed V _{n of} the optical head obtained earlier is obtained in exactly the same manner as in the flowchart of FIG.
Is corrected by the correction lens speed to calculate the correction speed V _n '(S8). Also, the correction command value to the linear motor 14 with a speed V _n 'is calculated (S9), the linear motor 14 and outputs the obtained command value to the driver is driven (S10). Thus, a series of control operations is completed, and the same process is repeatedly performed at a predetermined control cycle, so that the optical head seeks to the target track while following the target speed as shown in FIG. 8A.

As described above, also in this embodiment, the lens moving speed is passed through the low-pass filter to extract low-frequency components, thereby removing the influence of quantization errors and obtaining a moving speed closer to the actual lens moving speed. be able to.
Therefore, the speed of the optical head can be accurately corrected, and more stable speed control can be performed.

In the above embodiment, the optical disk recording / reproducing apparatus has been described as an example. However, the present invention is not limited to this, and can be suitably used for seek control of a head in a magnetic disk apparatus.

[0044]

As described above, according to the present invention, the relative displacement or speed of movement between the objective lens and the optical head during the coarse seek is detected, and based on the detected value. Since the seek speed at the time of the coarse seek is corrected, disturbance of the speed control due to the vibration of the objective lens during the coarse seek can be prevented, and the coarse seek can be performed accurately and stably.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing one embodiment of an information recording / reproducing apparatus of the present invention.

FIG. 2 is a time chart showing a relationship among a target speed and a detected speed, a drive current of a linear motor, an output of a lens position detector, and a lens speed in the embodiment of FIG.

FIG. 3 is a flowchart showing a speed control operation of the embodiment of FIG. 1;

FIG. 4 is a configuration diagram showing another embodiment of the present invention.

5 is a time chart showing a relationship among a target speed and a detected speed, a drive current of a linear motor, and an output of a lens angular velocity detector in the embodiment of FIG.

6 is a flowchart showing a speed control operation of the embodiment of FIG.

FIG. 7 is a diagram showing an objective lens position in the embodiment of FIG. 1, a lens moving speed detected thereby, and a lens moving speed obtained by averaging in still another embodiment of the present invention.

FIG. 8 shows a relationship between a target speed and a detected speed, a drive current of a linear motor, an output of a lens position detector, a lens position after canceling an eccentricity, and an obtained lens speed in still another embodiment of the present invention. It is a time chart.

FIG. 9 is a flowchart showing a speed control operation of the optical head of the embodiment of FIG.

FIG. 10 is a flowchart showing a speed control operation of an optical head according to still another embodiment of the present invention.

11 is a diagram showing the position of the objective lens and the lens moving speed extracted by the low-pass filter in the embodiment of FIG.

FIG. 12 is a diagram for explaining a general recording / reproducing head speed control method.

FIG. 13 is a diagram for explaining a problem of the conventional speed control.

[Explanation of symbols]

 Reference Signs List 1 optical disk 2 optical system 3 tracking error detector 4 focus error detector 6 digital signal processing unit 7 I / O control unit 8 DSP (digital signal processor) 10 driver 12 tracking actuator 13 focus actuator 14 linear motor 15 lens position detector 16 Lens angular velocity detector

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-2-267742 (JP, A) JP-A 1-2220138 (JP, A) JP-A-2-292738 (JP, A) JP-A 3- 127337 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) G11B 7/085 G11B 21/08

Claims (6)

(57) [Claims] 1. A first moving means for coarsely seeking an optical head in a direction transverse to a track of an information recording medium, and for moving a light beam to a target position after the coarse seek.
Second moving means for moving the objective lens in the head, means for detecting a seek speed of the objective lens , and means for calculating a target seek speed according to a residual distance to a target position And the detected seek speed and
An information recording / reproducing apparatus having control means for controlling the speed of the first moving means at the time of coarse seek based on a target seek speed , the phase between the objective lens and the head during coarse seek;
Means for detecting an opposing movement displacement or movement speed, and correcting the detection value of the seek speed detection means based on the detection value of the movement displacement or movement speed detection means ,
An information recording / reproducing apparatus provided with a correction means for removing a variation in a seek speed at the time of a coarse seek due to vibration of an objective lens . Wherein said moving speed detection means, the objective lens
2. The information recording / reproducing apparatus according to claim 1, wherein a moving speed is detected from a relative displacement between the head and the head . 3. The information recording apparatus according to claim 1, wherein said correction means corrects a seek speed detection value by subtracting a detection value of said moving speed detection means from a detection value of said seek speed detection means. Playback device. 4. The correction means includes: storage means for storing a detection value of the moving speed detection means; and an average value of a previous detection value and a detection value detected this time stored in the storage means. Means for calculating the seek speed, wherein the seek speed detection value is corrected by subtracting the averaging value obtained by the averaging calculation means from the detection value of the seek speed detection means. 1. An information recording / reproducing device. 5. The correction means has a low-pass filter for extracting a low-frequency component from an output of the moving speed detection means, and calculates a value extracted by the low-pass filter from a detection value of the seek speed detection means. 2. The information recording / reproducing apparatus according to claim 1, wherein the seek speed detection value is corrected by subtraction. 6. A means for detecting the amount of eccentricity of the recording medium, and applying the detected eccentricity to the second moving means in synchronization with a rotation cycle of the recording medium. Means for removing an eccentric component from a detection value of the seek speed detecting device; and
From the relative displacement between the objective lens and the head
By doing so, the detection value of the movement displacement detection means
2. An information recording / reproducing apparatus according to claim 1, further comprising means for removing eccentricity .