JPH06251520A - Information recording/reproducing device - Google Patents

Abstract

PURPOSE:To stably control a seeking by correcting the fluctuation of a seeking detection speed generated by outside disturbance. CONSTITUTION:This information recording/reproducing device is provided with a linear motor 14 for roughly seeking a recording/reproducing head in the track crossing direction of an optical disk 1, an actuator 12 for densely seeking the recording/reproducing section of the head to a target after this rough seeking, a means for detecting the seeking speed of the recording/reproducing section of the head, a means for calculating a target seeking speed in accordance with a remaining distance to the target position and a controlling means for controlling the linear motor 14 and the actuator 12 based on the detective speed and the target speed and seeking the recording/reproducing section of the head to the target position. It is also provided with a correction means for correcting the moving speed of the actuator 12 based on the detecting means and the detection value of the seeking speed detecting means based on the detection value of the moving speed detecting means and erasing the fluctuation amount of the seeking detection speed caused by the vibration of the actuator 12.

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 or 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 to move the head to a target position quickly and accurately. In general,
As a speed control method for such a recording / reproducing head, there is a method in which an operation schedule (speed profile) to the target position of the head is determined in advance, and the speed during the operation of the head is detected and the head is controlled so as to follow the operation schedule. Has been taken. FIG. 12 is a diagram showing a general control method thereof, where V _ref is a reference speed representing a planned operation speed, and V _n is a speed detected during seek. Further, here, the relationship between the velocity profile and the applied current of the coarse actuator (linear motor) for driving the carriage that moves the head is shown.
The reference speed V _ref is a speed calculated according to the residual distance to the target, and is calculated 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 a deceleration acceleration, and N is a zero-cross count value, and the moving distance can be known from this count value. In order to control the speed of the head, a command value to the linear motor is calculated from the target speed V _ref and the current speed V _{n at} that time at regular intervals, and the feedback is performed so that the speed of the head follows the target speed. Can be applied. The command value A _ct for the linear motor is calculated by the following equation. However, K is a feedback gain.

A _ct = K (V _ref −V _n ) ... (2) As described above, as shown in FIG. 12, the linear motor is first supplied with the acceleration current, and the head speed is accelerated to reach the target. When the speed is reached, the current of the linear motor turns into a deceleration current, and thereafter the speed decelerates following the target speed.
When the target position is reached, the speed becomes 0 and the seek operation is completed.

Here, when detecting the speed of the recording / reproducing head, the detection method is used differently depending on the high speed region and the low speed region of the speed. Specifically, first, in the high speed range, a track count method is used in which the speed is detected from the number N of tracks traversed by the head within a predetermined sampling interval T _S. The speed according to the track count method is calculated by the following equation.

V _n = (λ / 2N) / T _S (3) On the other hand, in the low speed region, between the tracks where the zero cross points of the tracking error signal are detected and the speed is detected from the time T _d between the zero cross points. Counting method is used.
That is, the distance between the zero cross points is 1 / the track pitch λ.
Since it is 2, the speed can be detected if the passing time of this 1/2 pitch is known. Speed V at this time
_n is calculated 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 faster than the reference speed value. Is a track count system that supports high-speed range,
When the speed becomes slower than the reference speed value, switching is performed such as a track-to-track count method corresponding to the low speed range.

[0008]

By the way, in the prior art, for example, when a light beam in optical recording is accessed to a target position, the recording / reproducing head is moved by driving the coarse actuator as described above. In order to access the target track with the beam, the objective lens in the head is further moved by the fine actuator to accurately access the target track.
The coarse actuator referred to here refers to a linear motor that moves the head roughly to the vicinity of the target position, and generally employs a so-called two-stage actuator configuration having such a coarse actuator and a fine actuator. However, when such a two-stage actuator is used, since the dense actuator is mounted on the linear motor and the weight of the linear motor itself is relatively heavy, when the linear motor starts or stops. The dense actuator vibrates. 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)
Is a drive current of the linear motor corresponding to the speed shown in FIG. 13A, and FIG. 13C is a view showing the position of the objective lens by the fine actuator. When there is no vibration of the dense actuator, the head speed 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 stop of the linear motor at point S in the figure, a vibration component is applied to the head and the objective lens vibrates as shown in FIG. 13 (c). Becomes The movement of the objective lens due to this vibration directly affects the detection of the relative speed between the head and the surface of the recording medium, and as shown in FIG.
B and C have a velocity including a vibration component. When the dense actuator vibrates in this way, not the true speed of the head but the speed generated by the vibration of the lens is detected. At this time, the speed control system controls to follow the target speed, and the speed control becomes unstable. In the worst case, there is a problem that the speed control loop oscillates.

The present invention has been made in order to solve such a problem, and its purpose is to correct the fluctuation of the detection speed due to the vibration of the dense actuator, and to perform the stable seek operation. To provide a device.

[0011]

SUMMARY OF THE INVENTION An object of the present invention is to provide a first moving means for roughly seeking a recording / reproducing head in a track crossing direction of an information recording medium, and a recording / reproducing section of the head after the rough seeking. Second moving means for densely seeking to the target position, means for detecting the seek speed of the recording / reproducing portion of the head, and calculating the target seek speed according to the residual distance to the target position. And a control means for controlling the first and second moving means based on the detected speed and the target speed to cause the recording / reproducing portion of the head to seek to the target position. In the apparatus, means for detecting the movement displacement or movement speed of the second movement means, and the detection value of the seek speed detection means are corrected based on the detection value of the movement displacement or movement speed detection means. Previous It is achieved by an information recording and reproducing apparatus characterized in that a correcting means for removing the variation in the seek detection speed due to vibration of the second moving means.

[0012]

Embodiments of the present invention will now be described 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 disc recording / reproducing apparatus using an optical disc as a recording medium will be described as an example. In FIG. 1, reference numeral 1 denotes an optical disc which is an information recording medium, and is rotated 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 disc 1 or reproducing recorded information on the optical disc 1. The optical system 2 is a semiconductor laser which is a light source for recording and reproducing, an objective lens for focusing a laser beam of the semiconductor laser into a minute light spot and irradiating it on the optical disc 1, and a sensor for detecting reflected light from the optical disc 1. It is composed of various optical elements. Reference numeral 12 is a tracking actuator for moving the objective lens in the optical system 2 in the radial direction of the optical disc 1, and 13 is a focus actuator for moving the objective lens in the direction perpendicular to the surface of the optical disc 1. The two actuators 12 and 13 and the optical system 2
Is integrated as an optical head and is configured to be movable in the radial direction of the optical disc 1. Reference numeral 14 is a linear motor for moving the optical head in the radial direction of the optical disk 1, and 10 is a driver for driving the linear motor 14.

Reference numeral 3 is a tracking error detector for detecting a tracking error signal based on the output of a sensor in the optical system 2, and 4 is a focus error detector for similarly detecting a focus error signal based on the sensor output. 1
Reference numeral 5 denotes a lens position detector for detecting the radial lens position of the focusing objective lens. Each error signal and 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.

The digital signal processing unit 6 is a digital control unit which is a main control unit of the optical disc recording / reproducing apparatus, and an I / O control unit 7 for controlling signal input / output, and arithmetic operations required for control according to a predetermined control program. It is composed of a digital signal processor (abbreviated as DSP hereinafter) 8 for executing processing and a memory 9 for storing various data. The digital signal processing unit 6 controls the tracking actuator 12 and the focus actuator 13 described above to perform tracking control and focusing control of the light beam, seek operation for moving the optical head to a designated position, and to the designated position. The recording / reproducing operation of the entire apparatus is controlled by controlling the recording and reproducing of the information. Reference numeral 11 denotes a digital command value calculated by the DSP 8 at the time of tracking control, focusing control, or seek control of the optical head, which is converted into an analog value to convert each actuator 12, 1
3 and the 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 seek operation of the optical head, and FIG. 2 (a) shows a speed profile (scheduled travel speed curve to a target position) at the time of seek and an actually detected speed signal. It is a figure. Here, two speed signals are shown as the speed signal when the tracking actuator 12 vibrates and when the tracking actuator 12 does not vibrate. 2B is a drive current of the linear motor 14 at the time of seek, FIG. 2C is an objective lens position detected by the lens position detector 15, and FIG. 2D is the lens position detector 1.
This is the speed of the objective lens obtained by the DSP 8 based on the detected value of 5. Further, FIG. 3 shows the DSP 8 when seeking the optical head.
FIG. 6 is a flowchart showing the flow of the processing of FIG. 6 and is a diagram showing an interrupt routine of speed control executed at a 4 KHz cycle.

First, when a recording or reproducing command is issued from an external control device (not shown) and the recording / reproducing position of the optical disk 1 is instructed, 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 the command value to the linear motor 14 at regular intervals based on the obtained speed and the target speed. Performs speed control of the optical head. Specifically, as shown in FIG. 3, the DSP 8 inputs a track count value, which is the number of tracks that the light beam has traversed the information track of the optical disc 1 from a counter (not shown) (S1), and based on this, the present time of the optical head. The speed V _n and the target speed V _ref are calculated (S2).
As described above, the current speed V _n is divided between the track counting method and the track-to-track counting method depending on the low speed area and the high speed area. 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 To be
However, 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 the command value to the linear motor 14 is calculated using the obtained correction value (S7). This command value is calculated by the above-described equation (2), converted into an analog value by the D / A converter 11, and then given to the driver 10 so that the linear motor 14
Is driven. The detection speed correction processing will be described in detail later. In this way, the DSP 8 repeatedly executes the series of processes of S1 to S8 described above, and as a result, the linear motor 14 is supplied with the acceleration current as shown in FIG. 2B, and the speed of the optical head becomes as shown in FIG. As shown, it accelerates toward the target speed. Then, when the target speed is reached, the current of the linear motor 14 turns into a deceleration current, and the speed of the optical head decelerates while following the target speed.

Here, it is assumed that the tracking actuator 12 vibrates due to some disturbance at point A in FIG. Due to this vibration, the objective lens provided in the optical system 2 is not fixed to the center as shown in FIG. The DSP 8 corrects the detection speed due to vibration in the series of control processes described above. 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 this lens position (S4). This can be obtained as the difference between the lens position captured last time and the lens position captured this time. Next, the DSP 8 multiplies the obtained value by the correction gain of the detection speed according to the lens speed (S5), and corrects the detection speed V _n with the lens speed V _L (S6). Modified velocity V _n 'is determined by the following equation. However, k is a correction gain and is an arbitrary constant.

V _n ′ = V _n −k · V _L (6) In this way, the DSP 8 corrects the detected speed and calculates the command value of the linear motor 14 using the obtained correction value V _n ′ (S
7), output to the driver 10 (S8). For example, at point _A , the detected speed is V _A due to the vibration of the actuator, and at point _B, it becomes V _{B. As} shown in FIG.
The correction speed is calculated by subtracting the lens speeds a and b at point B and point 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 is removed and the disk surface. At the point D in FIG. 2A, the DSP 8 switches the optical head speed detection method from the track count method to the inter-track count method, and the number of remaining tracks up to the target is, for example, several tens.
At this level, the coarse seek control of the optical head by the linear motor 14 is switched 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 on or reproduced from 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 that detects the position of the objective lens, and the lens speed is subtracted from the detected current speed. As a result, the vibration component of the actuator can be removed, and the speed can be corrected accurately. That is, when vibration occurs in the actuator, the detection speed is detected including a vibration component such as V _A and V _B as shown in FIG. 2A. By removing such a vibration component, It becomes possible to detect an accurate speed. Therefore, even if the actuator vibrates, the vibration of the current generated by the vibration of the actuator as shown by the broken line in FIG. 2 (b) is eliminated, so that stable speed control is performed without disturbance of speed control. You can

FIG. 4 is a block diagram showing another embodiment of the present invention. In the embodiment of FIG. 1, the speed of the objective lens is detected based on the output of the lens position detector, but 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 is a lens angular velocity detector for detecting the angular velocity in the rotation direction of the objective lens provided in the optical system 2. 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 velocity of the optical head as described later in detail. Other configurations are the same as those in FIG.

FIG. 5 is a diagram showing the signals of the respective parts of FIG. 4, FIG. 5 (a) is the target speed and the detection speed of the optical head, and FIG. 5 (b).
Is the drive current of the linear motor, and FIG. 5C is the output of the lens angular velocity detector 16. Further, FIG. 6 is a flowchart showing a flow of speed control processing at the seek time of the optical head of the present embodiment, which is a speed control routine executed at a 4 KHz cycle. Since the basic speed control operation is the same as that of the embodiment shown in FIG. 1, detailed description thereof will be omitted, and here, the seek speed correction operation 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 speed detector 16 (S3) and calculates the lens speed based on it (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, it is possible to obtain the fluctuation of the detected speed caused by the disturbance.
The lens speed V _L is calculated 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.

Next, the DSP 8 multiplies the obtained lens speed by the correction gain k (S5), and corrects the detected speed V _n by the lens speed (S6). The correction speed V _n ′ is obtained by the above-mentioned equation (6). For example, FIG.
At point B, the detection speed is V _B due to the vibration of the actuator.
Although than it is detected as, the rotation angular velocity of the lens at the point B as shown in FIG. 5 (c) is b, the correction velocity V _n 'is at the point B _{V n - (V B -k ·} b・ L). The DSP 8 calculates a command value using the obtained correction speed (S7) and outputs it to the driver 10 (S8). Therefore, in this embodiment as well, in order to control the speed of the optical head by correcting the detection speed based on the lens angular speed each time the speed is detected and controlling the speed of the optical head by the speed signal from which the effect of vibration is removed, Similarly, even if vibration occurs in the actuator, the control is not disturbed and stable seek control can be performed.

Here, in the above-described embodiment, the lens position detection performance is equivalent to the speed signal detection performance.
It is important to correct the detection speed accurately, but generally it can be said that the lens position detection performance is worse than the speed signal detection performance. Further, when the seek control is performed digitally, the influence of the quantization error is large, which may disturb the seek control. 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 obtained from the lens position shown in FIG. 7A. When the lens is moving at a speed of approximately p as indicated by a broken line A in FIG. 7A, due to the influence of electrical noise, quantization noise, or disturbance at a high frequency other than vibration by the carriage, A stepped lens position as shown by A'is obtained. Further, when the lens moving speed is obtained from this lens position, a velocity signal vertically vibrating around the actual lens moving speed B is obtained as indicated by B'in FIG. 7B. Therefore, an example in which the above-mentioned problems are solved will be described.

In this embodiment, the lens position detector 15 shown in FIG. 1 is used.
The lens speed is corrected by taking the arithmetic mean of the lens position detected last time and the lens position this time. In addition, this embodiment is the optical disc 1 of FIG.
The effect of eccentricity is removed so that the lens speed can be corrected more accurately.

FIG. 8 is a diagram showing signals at various parts during seek operation of the optical head in the present embodiment. FIG. 8A shows a speed profile (scheduled operation speed curve to a target position) at the time of seek and actually. It is the figure which showed the detected speed signal. Here, the tracking actuator 1 is used as a velocity signal.
Two velocity signals are shown, with and without vibration at 2. 8B is a drive current of the linear motor 14 at the time of seek, and FIG. 8C is a lens position detector 15.
It is the objective lens position detected in. When the optical disc 1 is rotated at a constant rotation cycle, eccentricity occurs due to the deviation of the center of the optical disc 1 from the rotation center, and such eccentricity affects the relative positional relationship between the optical head and the optical disc 1. For example, even if the linear motor 14 runs at a constant speed and the tracking actuator 12 is fixed to the mechanical center, the relative speed between the optical head and the disk surface does not become a constant value, and a speed deviation of a constant cycle caused by eccentricity occurs. Will be rippling. The lens position shown in FIG. 8C is wavy at a constant period due to the influence of the decentering. Figure 8 (d)
Is the lens position after removing the eccentricity, and FIG.
It is the lens speed obtained from the lens position in (d).

FIG. 9 is a flow chart showing the processing flow of the DSP 8 at the time of optical head seek in this embodiment. The processing of FIG. 9 is a flow chart showing an interrupt routine for performing interrupt processing at a cycle of 4 KHz, for example. In FIG. 9, first, when a recording or reproducing command is issued from an external control device (not shown) and the recording / reproducing position of the optical disc 1 is instructed, the digital signal processing unit 6 determines from the current position and the target position of the optical head. The residual distance is calculated and the seek operation control to the target position is started. In the speed control during the seek operation, the DSP 8 detects the speed of the optical head as described above, and calculates the command value to the linear motor 14 at regular intervals based on the obtained speed and the target speed. Performs speed control of the optical head. Specifically,
The DSP 8 inputs a track count value, which is the number of tracks where the light beam has crossed the information track of the optical disc 1 from a counter (not shown) (S1), and based on this, calculates the current speed V _n of the optical head and the target speed V _ref . Yes (S2).
As described above, the current speed V _n is divided between the track counting method and the track-to-track counting method depending on the low speed area and the high speed area.

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

That is, in order to effectively remove the influence of this 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 is set as the rotation cycle of the spindle motor during the seek operation. It is applied to the tracking actuator 12 in synchronization. Therefore, the periodic velocity deviation due to the eccentricity that is synchronized with the rotation period of the spindle motor is removed by eccentrically driving the lens by the tracking actuator 12, and the velocity control of the linear motor 14 is not affected. Here, the linear motor 1
When 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 and control the speed displacement due to 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 lens position this time (S6). That is, the previous lens position is stored in the memory 9, and when the lens position from which the eccentricity is removed is obtained this time, the lens speed is obtained by subtracting the previous lens position from the present lens position (S6). The obtained lens speed is stored in the memory 9. Next, the lens speed obtained this time and the previous lens speed stored in the memory 9 are added, and the obtained added value is divided by 2 to perform addition averaging, and the corrected lens speed is calculated. (S7). However, the previous lens speed at this time was not obtained by the 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.

Then, the DSP 8 corrects the previously detected current speed V _n by the correction lens speed LP_V (S8). Modified velocity V _n 'is determined by the following equation.
However, k is a correction gain and is an arbitrary constant.

V _n ′ = V _n −k (correction lens speed: LP_V) (8) When the correction speed V _n ′ is calculated, the DSP 8 calculates the command value to the linear motor 14 using the obtained correction value. Do (S
9). This command value is calculated by the equation (2) described above, converted into an analog value by the D / A converter 11, and then given to the driver 10 to drive the linear motor 14 (S10). With the above, a series of control operations of the DSP 8 is completed, and the same processing is executed again in the next control cycle. In this way, the DSP 8 repeats the same control at a cycle of, for example, 4 KHz, and 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.
Then, when the target speed is reached, the linear motor 1
The current of 4 turns into a deceleration current, and the speed of the optical head decelerates while following the target speed.

Here, it is assumed that the tracking actuator 12 vibrates due to some disturbance at point A in FIG. Due to this vibration, the objective lens provided in the optical system 2 is not fixed to the center as shown in FIG. Further, because of this vibration, the detection speed is detected including a vibration component such as V _{A at} the point _A and V B at the point _B , but 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, as described above, it is affected by the quantization error,
As shown in FIG. 7B, the lens speed becomes a speed signal that oscillates vertically with respect to the actual lens speed.

On the other hand, in this embodiment, since the speed of the objective lens is corrected by taking the arithmetic mean of the previous lens speed and the present lens speed, the previous lens speed is changed as shown in FIG. 7B. If v ₁ and the current lens speed are v ₂ , the addition average value is v ₂ ′, and the previous lens speed is v ₂ and this time is v ₃ , the addition average value is v ₃ ′ and the addition is performed. The value obtained by the average value is an intermediate value between the lens movement speeds of the previous time and this time. Therefore, the speed signal C obtained by taking the arithmetic mean as shown in FIG. 7B is much closer to the actual lens moving speed B as compared with the embodiment described in FIGS. A more accurate lens moving speed can be obtained. Therefore, the seek speed of the optical head can be corrected more accurately by correcting the speed of the optical head using the correction lens speed obtained by the averaging in this way.

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

As described above, in the present embodiment, the lens speed due to the vibration of the actuator is calculated by the arithmetic mean of the previous speed and the present speed, so that the influence of the quantization error as described above is removed and the actual lens speed is obtained. It is possible to obtain a correction lens speed close to, and it is possible to more accurately correct the speed of the optical head. Moreover, by measuring the displacement of the lens due to the eccentricity of the optical disc and applying this to the actuator in synchronization with the disc rotation cycle, the head speed can be accurately corrected regardless of the vibration of the actuator due to disturbance or the eccentricity of the optical disc. You can Therefore, since the accurate speed can be detected regardless of the disturbance or the eccentricity, the vibration of the current as shown by the broken line in FIG. 8B is eliminated, and the stable speed control can be performed without the disturbance of the speed control. it can.

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

Here, the process of extracting the low frequency component of the lens velocity by the low pass filter will be described with reference to FIG. 11. First, A in FIG. 11A is the actual lens position,
A'is a lens position detected by the lens position detector 15. This lens position becomes a stepped lens position due to the influence of electrical noise, quantization noise, or disturbance at a high frequency other than vibration by the carriage as described above. When the moving speed of the lens is obtained from this lens position, a speed signal that vibrates up and down with respect to the actual moving speed of the lens is obtained as indicated by B'in FIG. 11 (b). Therefore, if the low-pass component is extracted by passing the moving speed of the lens indicated by B ′ through a low-pass filter, as shown in FIG.
A velocity signal as shown by C in (b) can be obtained.
That is, the rectangular wave velocity signal obtained in S6 is integrated through a low-pass filter to obtain C in FIG.
As shown by, the 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 previously is exactly the same as in the flowchart of FIG.
Is corrected by the correction lens speed to calculate the correction speed V _n ′ (S8). Further, the command value to the linear motor 14 is calculated using this correction speed V _n ′ (S9), and the obtained command value is output to the driver to drive the linear motor 14 (S10). In this way, a series of control operations are completed, and by repeating the same processing at every predetermined control cycle, the optical head seeks toward 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 the low-frequency component, thereby eliminating the influence of the quantization error 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 embodiments, the optical disk recording / reproducing apparatus has been described as an example, but the present invention is not limited to this, and can be suitably used for head seek control in a magnetic disk apparatus.

[0044]

As described above, according to the present invention, the speed control caused by the vibration of the fine actuator is performed by detecting the moving speed of the objective lens due to the vibration of the fine actuator and correcting the fluctuation of the detected value of the seek speed. The effect of being able to prevent the disturbance of the data and performing seek control accurately and stably.

[Brief description of drawings]

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

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

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

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

5 is a time chart showing the relationship among the target speed, the detection speed, the drive current of the linear motor, and the output of the 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 and 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 the relationship between the target speed and the detected speed, the drive current of the linear motor, the output of the lens position detector, the lens position after canceling the eccentricity, and the obtained lens speed in yet another embodiment of the present invention. It is a time chart.

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

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

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

[Explanation of symbols]

 1 Optical Disc 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

Claims (7)

[Claims] 1. A first moving means for roughly seeking the recording / reproducing head in a track transverse direction of an information recording medium, and a first moving means for densely seeking a recording / reproducing portion of the head to a target position after the rough seeking. 2 moving means, means for detecting the seek speed of the recording / reproducing portion of the head, means for calculating the target seek speed according to the residual distance to the target position, the detected speed and the target An information recording / reproducing apparatus having a control means for controlling the first and second moving means based on speed to seek the recording / reproducing portion of the head to a target position. A means for detecting a moving displacement or a moving speed, and a detection value of the seek speed detecting means are corrected on the basis of a detected value of the moving displacement or the moving speed detecting means to obtain a seek by vibration of the second moving means. An information recording / reproducing apparatus, comprising: a correction unit for removing a fluctuation in the detection speed. 2. The information recording / reproducing apparatus according to claim 1, wherein the moving speed detecting means detects the moving speed from a difference in displacement of the second moving means. 3. The information recording / reproducing according to claim 1, wherein the moving speed detecting means detects the moving speed of the second moving means from an angular speed of a converging portion which converges a recording / reproducing portion of the head. apparatus. 4. The information recording according to claim 1, wherein the correction unit corrects the seek speed detection value by subtracting the detection value of the moving speed detection unit from the detection value of the seek speed detection unit. Playback device. 5. The correction means stores a storage means for storing the detection value of the moving speed detection means, and an addition average value of the previous detection value and the detection value detected this time stored in the storage means. And a means for calculating, wherein the seek speed detection value is corrected by subtracting the arithmetic mean value obtained by the arithmetic mean calculation means from the detection value of the seek speed detection means. 1. Information recording / reproducing apparatus. 6. The correction means has a low-pass filter for extracting a low-frequency component from the output of the moving speed detection means, and a value extracted by the low-pass filter from a detection value of the seek speed detection means is obtained. The information recording / reproducing apparatus according to claim 1, wherein the seek speed detection value is corrected by subtraction. 7. A means for detecting the amount of eccentricity of the recording medium, and applying the detected amount of eccentricity to the second moving means in synchronization with the rotation cycle of the recording medium, 2. The information recording / reproducing apparatus according to claim 1, further comprising means for removing an eccentricity from the detection value of the seek speed detecting means.