JPH05114261A - Information recording and reproducing device - Google Patents

Abstract

PURPOSE:To provide an information recording and reproducing device for magnetic disk devices, optical disk devices, etc., provided with a positioning mechanism which can quickly follow the variation of a track with high accuracy. CONSTITUTION:A track position detecting head 15 for detecting the variation of a track 3 synchronously to the rotation of a disk prior to a recording and reproducing head 4 is provided and the variation of the track is offset by adding a signal corresponding to the detected variation of the track to the positioning servo system of the head 4 in the forward direction. Since the positional variation of the track, especially, the positional error of the head 4 caused by a component synchronous to the rotation of the disk can be reduced, the followup ability and, accordingly, the positioning accuracy of the head 4 can be improved.

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 (including information recording or only information reproducing) in a magnetic disk device, an optical disk device or the like, and particularly highly accurate positioning is required. The signal recording / reproducing means is suitable for an information recording / reproducing apparatus including a positioning servo mechanism.

[0002]

BACKGROUND OF THE INVENTION The present invention relates to a positioning servo mechanism for signal recording / reproducing means common to information recording / reproducing devices such as magnetic disk devices and optical disk devices. Here, a magnetic disk device will be described below as a conventional technique.

In a signal recording / reproducing means (hereinafter referred to as a magnetic head) positioning servo mechanism of a conventional magnetic disk device, the magnetic head reads position information recorded on a track, and uses this as a position deviation signal, The servo control system was configured so that the position deviation would be zero. For this, for example, "Magnetic Recording" published by McGraw-Hill (CD Mee et al. Magnetic recor
ding, McGraw-Hill, Inc.) discloses the technique.

As the recording density is improved, the positioning accuracy becomes severer year by year, and the demand for the track following performance of the positioning servo mechanism is also increasing. In the positioning servomechanism, the magnetic head must always follow the center of the track written on the rotating disk, but the track position fluctuates due to various factors, and the magnetic head follows this fluctuating target. Must.

In recent years, in magnetic disk devices, the track density is approaching 3,000 TPI (track per inch), and the positioning accuracy is required to be 0.2 to 0.3 μm. At this time, the positioning error caused by the track fluctuation becomes almost equal to the required positioning accuracy, and reduction of this positioning error has become an important issue. To reduce this, there are methods for improving mechanical processing accuracy and assembly accuracy, but these are approaching their limits. Therefore, in addition to the improvement in the mechanical aspect, it is necessary to develop a magnetic head positioning servo system capable of highly precise track following.

In the conventional servo mechanism, the positioning error, which is the relative displacement between the target track and the magnetic head, is determined by the tracking performance of the feedback system. In order to improve the tracking performance, the loop gain of the feedback system may be increased, but in reality, there is a problem that the servo system oscillates when the gain is increased due to the resonance characteristics of the mechanical system. Therefore, the followability can be increased only within the range where the stability of the feedback system is secured, and the followability is limited.

On the other hand, in order to overcome this, there is a method of detecting the fluctuation of the target track and adding it to the servo system in a feedforward manner. This idea is described as a control theory in Chapter 10.1 of "Control and Dynamical Systems" by Takahashi and Auslanda et al. Further, as an example applied to a magnetic disk device, for example, Japanese Patent Laid-Open No. 1-27721
This idea is disclosed in Japanese Patent Laid-Open No. 1-246610. According to Japanese Patent Laid-Open No. 1-21772, when a magnetic head is positioned by a sensor mounted on the access motor side in a semi-closed loop, an offset due to temperature change occurs, so a fixed magnetic head is provided to correct this. A change in a specific track is detected and a constant value is added to the servo system. Further, JP-A-1-246610 uses a position signal of an actuator for driving the magnetic head in addition to a relative position signal between the magnetic head and the disk in order to improve the control performance of the sector servo system.

Actually, the track fluctuation has complicated characteristics due to eccentricity, vibration at the time of writing the servo track, etc., and a method of directly measuring the track fluctuation factor to be removed is essential.

[0009]

SUMMARY OF THE INVENTION An object of the present invention relates to a signal recording / reproducing means positioning mechanism of an information recording / reproducing apparatus,
In particular, it is an object of the present invention to provide a positioning servomechanism that allows the signal recording / reproducing means to follow the fluctuation of the track in the radial direction of the disk at high speed and with high accuracy.

[0010]

In order to solve the above-mentioned problems, a track position detecting means for detecting a position change of a track with respect to a signal recording / reproducing means before the signal recording / reproducing means, and a track position detecting means. Means for adding a signal corresponding to the track position fluctuation to the control means so as to cancel the track position fluctuation.

Further, the track position detecting means for detecting the position fluctuation of a specific track prior to the signal recording / reproducing means and the signal corresponding to the track position fluctuation detected by the track position detecting means cancel the track position fluctuation. And means for adding to the positioning control means.

Further, the position detecting means for detecting the positional change in the radial direction of the disk prior to the signal recording / reproducing means, and the signal corresponding to the radial positional change of the disk detected by the position detecting means are transmitted in the radial direction of the disk. And a means for adding to the positioning control means so as to cancel the position fluctuation of.

Further, memory means for storing track position fluctuations, means for detecting a time point when the signal recording / reproducing means is positioned after moving to a target track, and a signal of the detecting means for the positioning control means of the memory. It is provided with a unit for reading the data of the position variation corresponding to the target track among the contents, and a unit for adding the read data to the control unit.

Also, memory means for storing track position fluctuations, means for detecting a time point when the signal recording / reproducing means is positioned after moving to a target track, and a signal of the detecting means for the positioning control means of the memory. Of the contents, means for reading the data of the position variation corresponding to the target track, means for adding the read data to the control means,
Position detecting means for detecting the displacement of the support member for supporting the signal recording / reproducing means, means for indicating that the signal recording / reproducing means is positioned on the target track, and position information of the position detecting means after the positioning is held and this And a switching means for switching the control amount of the control means for positioning the signal recording / reproducing means to the output of the position detecting means.

Further, the acceleration detecting means provided at the tip of the signal recording / reproducing means, the means for extracting the position signal of the signal recording / reproducing means from the output signal of the acceleration detecting means, and the signal obtained from the output signal of the acceleration detecting means. A means for obtaining a signal corresponding to the track position fluctuation from the difference between the position signal of the recording / reproducing means and the track position signal detected by the signal recording / reproducing means, and a signal corresponding to the track position fluctuation for canceling the track position fluctuation. And means for adding to the control means.

Further, there are provided means for previously measuring a detection time difference between the position signals detected by the track position detecting means and the signal recording / reproducing means, and means for storing the detection time difference.

[0017]

According to the present invention, the relative displacement between the target track center and the signal recording / reproducing means is detected as a position error signal, and the fluctuation of the target track center is detected by another detector.
As a result, the displacements of both the target track center and the head can be obtained independently. Since the fluctuation of the target track center can be regarded as a position disturbance from the viewpoint of the servo loop, an operation amount is added to detect or estimate the fluctuation and cancel the position disturbance. As a result, it is possible to follow the track position variation regardless of the limited characteristics of the feedback loop.

Further, according to the present invention, there are provided a signal recording / reproducing means and a driving means thereof, a track position detecting means and a driving means thereof for detecting a track position variation prior to the magnetic head.
To the center of the disc on a straight line passing through the center of the disc,
It was placed in a position where they would substantially oppose each other. By adopting this configuration, the reaction force applied to the base portion by the signal recording / reproducing means and its driving means at the time of seek is canceled by the reaction force applied to the base portion generated by the driving of the track position detecting means and its driving means almost at the same time. Therefore, the vibration of the truck can be reduced without generating the vibration due to the reaction force in the base portion.

Further, since the track position detecting head detects only the position change of a specific track, a drive mechanism for the track position detecting head is not required and the track position detecting head does not move, so that the signal recording is performed. The positioning time of the reproducing means is shortened.

Further, by providing a sensor for measuring the position variation of the disk in the radial direction and applying the signal of this sensor to the positioning control means of the signal recording / reproducing means, the rotation synchronous vibration caused by the eccentricity of the disk is generated. It can be easily detected and the fluctuation in the position of the truck due to this vibration can be reduced.

Further, the position variation of each track is stored in correspondence with the sensor position provided on the carriage with reference to the index signal provided on the track in advance, and when the signal recording / reproducing means is moved to the target track by a seek command, it is applicable. By adopting a configuration in which the position variation signal of the track to be read is added to the control means of the read signal recording / reproducing means,
Immediately after the seek, the track position fluctuation can be corrected by the feed forward, and the time for starting the data recording / reproducing can be shortened.

[0022]

【Example】

(First Embodiment) FIG. 1 is a block diagram of a magnetic disk device including a control circuit for explaining a first embodiment of the present invention.
Although each of the embodiments described below was performed using a magnetic disk device, it can be similarly applied to an optical disk device.

A plurality of stacked disks 1 are rotated by a motor 2. Concentric tracks 3 on the disk surface
Are arranged, and magnetic signals are recorded on the tracks. This magnetic signal is recorded / reproduced by the recording / reproducing magnetic head 4 arranged on the disk surface. The magnetic head 4 is supported by a supporting member called an arm 5 and a carriage 6, and is driven by an actuator 7.
Each track is divided into a plurality of data areas called sectors, and position information is written in advance at the beginning of each sector. The magnetic head recognizes the current position based on this position information. This method is called the sector servo method,
The contents thereof are disclosed, for example, in the 663rd seminar of the Japan Society of Mechanical Engineers, "Positioning Technology in Magnetic Disk Drive" (1988). The magnetic head detects the position information written on the track, which represents a relative position deviation (position error signal) between the magnetic head and the track center.

Positioning of the magnetic head is performed by a position servo mechanism. The position error signal is demodulated by the demodulation circuit 8 and input to the digital servo controller 10 through the A / D converter 9 to obtain the error with the center of the target track, and the phase compensation calculator (Gc) 11 performs phase compensation. After that, the D / A converter 12 outputs the current to the power amplifier 13 and amplifies the current to drive the actuator 7. Upon receiving a data write or read command from a host computer (not shown), the target track generation circuit 14 sets a new target track in this positioning servo mechanism. At this time, since an error occurs with the current position, an operation amount for reducing the error is generated, a driving force is generated in the actuator, and the magnetic head moves. When the magnetic head is positioned at the target track center, the position error becomes zero and the magnetic head is positioned there. The operation of the magnetic head moving over the track is called seek, and the operation of following the center of the target track is called following.

The movement of the track written on the disc will be described below. The following points are considered as factors of truck fluctuation. Random track fluctuations due to bearing runout vibrations of the disk and shaft bearings. Rotation-synchronous vibration due to thermal change in eccentricity of the disk. Fluctuation of the track position signal due to head vibration etc. when writing the track position signal. Positional error due to radial component of disk out-of-plane vibration. Signal detection error due to the texture of the disk surface.

As described above, the factors causing the fluctuation of the truck are:
There are vibrations that are synchronized with the rotation cycle and asynchronous vibrations that are not so. The magnetic head must always be positioned at the track center following this track fluctuation.

Now, the position servo mechanism corrects the positional deviation caused by the track fluctuation. That is, since the position error signal is fed back to the controller, an operation amount that eliminates the error is generated by the compensation calculation, and the magnetic head follows the track fluctuation. In order to make the correction for the positional deviation strong, the correction operation may be performed even for a small magnitude of the position error signal. This corresponds to increasing the forward gain in the servo mechanism. However, in this method, if the driven mechanism has a delay or has resonance characteristics, the closed loop servo mechanism loses stability and oscillates. Therefore, it is actually necessary to set the followability within a range that does not impair the stability. Therefore, the head cannot sufficiently follow the track only by the compensation method based on this feedback.

By the way, if the fluctuation of the track is regarded as a position disturbance, it can be understood that this disturbance can be compensated by feedforward instead of feedback. In order to compensate by feedforward, it is necessary to detect or estimate a position disturbance.

As described above, the fluctuation of the track has a component synchronized with the rotation and a component not synchronized with it, and the thermal eccentricity of the disk, the track signal writing error, the detection error due to the texture, etc. are the synchronous vibrations and the asynchronous. The amplitude is large compared to vibration. Also, unlike asynchronous vibration, these can be detected in advance.

In this embodiment, in addition to the signal magnetic head for recording / reproducing the information signal, another head for detecting the fluctuation of the track position is provided. The track position detecting head 15 has the arm 1 similar to the signal magnetic head.
6, supported integrally by a carriage 17 and driven by an actuator 18. Further, the track position detecting head is installed so as to precede the signal magnetic head in the rotation direction of the disk.

Like the signal magnetic head, the track position detecting head receives a signal from the target track generating circuit upon receiving a seek command from the host controller, and via the compensating circuit 22, the D / A converter 23 and the power amplifier. The head is driven and positioned by 24. When the target track is positioned approximately on the track center, the head holding circuit 25 holds the head. This holding circuit may be a servo system in which the zero cross frequency of the open loop frequency characteristic is reduced to several tens Hz or less.

As a result, it becomes insensitive to high-frequency vibrations in the servo band which is a problem in positioning, and as a result, it is possible to detect a problematic track position fluctuation. Also, a method using another displacement sensor shown in the fifth embodiment may be used. In any case, the track position signal A / D converted via the demodulation circuit 19 represents the fluctuation of the track orbit, and can be regarded as a position disturbance for the positioning servo system. Therefore, this signal is forwardly added to the positioning servo system. For that purpose, a feedforward loop is added to measure the track position signal in advance by the time difference measuring means 5
It is added to the compensator 21 in consideration of the detection time difference between the track position detection head and the magnetic head, which is measured and stored by the 0 and time difference storage means 51. If the characteristic of the compensator 21 is set to the inverse characteristic of the control target of the positioning servo system, the track position fluctuation can be canceled out, and a highly accurate servo system can be realized.

The control contents described above will be explained more strictly by using mathematical expressions. FIG. 2 shows a block diagram of the servo system shown in FIG. From FIG. 2, the transfer characteristic from the target value r and the position disturbance d to the magnetic head track position error y which is a control amount is obtained. In the conventional method without a feedforward loop, its transfer characteristic is

[0034]

[Equation 1]

However, at the time of following, r = 0.

Here, the stability of the closed loop system and the position disturbance d
Compensator Gc that satisfies the cutoff property of Think about designing.

That is, the stable arrangement of the poles of the closed loop system 1 + Gc · Gp (Gc · Gp <1 in the small gain theorem) and y
Gc is designed so that = 0.d (Gc.Gp → ∞), but the stability and disturbance blocking characteristics are Gc.Gp <1 and Gc.Gp.
→ Requires contradictory characteristics such as ∞, and only a compromised design can be done. As an example of the design, it has been conventionally performed to increase Gc / Gp in order to improve the disturbance cutoff characteristic in a low frequency range, and to reduce Gc / Gp in a high frequency range with emphasis on stability. ..

However, since the head positioning servo system includes complicated mechanical resonance in the closed loop, the target track fluctuates, and the frequency bands of both are strictly mixed, the conventional control system has a higher level. Accurate track following is not possible.

On the other hand, when the feedforward is included, its transfer characteristic is

[0040]

[Equation 2]

It becomes If the characteristic of the element F is Gp- ¹ ,

[0042]

[Equation 3]

Therefore, the stability can be designed by Gc, and the disturbance blocking characteristic can be designed separately by F.

The operation of the magnetic disk device used in this embodiment will be described with reference to FIG. When the power of the magnetic disk device is turned on (F1), the rotation of the disk starts (F2) due to the initial processing of the microprocessor and the activation of the spindle motor. When this initial processing is completed, the initial processing operation of the servo system is performed. Here, the track position detection head and the signal magnetic head are positioned on the track on which the head is located at this time (F3), and the time difference between the signal magnetic head and the track position detection head is obtained from the detection signal at this time ( F4).

The time delay may be obtained, for example, by reading an index signal provided at one location on each track and obtaining it from the deviation of the reading time, or from the deviation of the waveform of the head position error signal waveform itself. Good. After that, a ready signal is issued to a host controller (not shown) to enable data reading and writing and wait for a command signal from the host.

When a seek command from the upper level is received (F
6) Both the track position detection head up to the target track and the signal magnetic head are moved and positioned (F7, F
14). When the signal magnetic head is positioned within a preset range (a in FIG. 3) of the center of the target track (F8), a signal notifying the upper layer that data can be reproduced is sent (F9), and the following state is set. (F10).

Further, when the track position detecting head is positioned within a preset range (b in FIG. 3) of the center of the target track (F15), the head is held (F16) and the track fluctuation is detected. (F1
7). A feedforward signal is obtained from this track fluctuation through the detection time delay measured in advance and the compensating element of F = Gp- ¹ in Formula 2 (F18). The obtained signal is added to the positioning servo system of the signal magnetic head (F11). As a result, the track following property is improved and the positioning error is reduced. Therefore, when the magnetic head is positioned within the preset range (c in FIG. 3) of the center of the target track (F12), signal recording is possible. A signal is sent to notify the host (F13).

Here, if the holding position of the track position detecting head is not at the average center position of the target track, adding this signal as feedforward may cause a constant offset in the signal magnetic head. However, since this signal is a signal in the low frequency range, it can be compensated by the feedback characteristic of the positioning servo system, and there is no problem. Then, the data is read and written on the track, and the servo mechanism waits for the next command from the higher order.

Further, in this embodiment, the feedforward signal is added so as to improve the positioning accuracy only when recording the data. In a magnetic disk device, it is important to record data with high accuracy, and even if the magnetic head is slightly misaligned during reproduction, if the accuracy of the recording signal is high, the probability of causing a read error is extremely small.

As described above, in the present embodiment, the position fluctuation of the track for reading and writing data which is synchronized with the rotation is detected prior to the signal magnetic head, and the signal for canceling this by feedforward is given to the positioning servo system. Higher tracking of fluctuations is possible, positioning accuracy is improved, and high density recording is possible.

In this embodiment, the case of the data surface servo system has been described, but the present invention can obtain the same effect with the servo surface servo system with substantially the same structure. In this case, since the position information is written only on the servo surface, only one head for detecting the track fluctuation may be provided on the servo surface.

(Second Embodiment) FIG. 4 shows a block diagram of the second embodiment. In this embodiment, the track position detecting head is fixed at a specific position. Then, of the track position fluctuations, only the disk fluctuations are detected and added to the positioning servo system as feedforward signals. The configuration and operation of the servo system are the same as those in the first embodiment, and the description will be omitted.

The track detected by the track position detecting head can be a laminar flow state in which the turbulent flow of gas on the disk surface or between the disks is substantially laminar. good.

In this embodiment, it is possible to reduce the position error of the component due to the disk variation such as the eccentricity in the track variation only by providing the fixed head. Further, since it is a fixed head, there is an effect that a driving mechanism is unnecessary and mounting is easy. There is one fixed head for each disk surface.
There may be one each, or only one may be mounted on any disc surface.

(Third Embodiment) FIG. 5 shows a block diagram of the third embodiment. In this embodiment, a sensor 100 for measuring the radial displacement of the outer circumference of the disk is provided instead of the fixed head shown in FIG. Then, the output of the displacement sensor 100 is input to the feedforward compensator 21 via the detection circuit 101 and the A / D converter 102 as in the first embodiment.
In the case of a device in which the position signal of the track is removed from the device and written (servo track write) and the device is mounted again, the amount of eccentricity generated during mounting is at least 1 to several μm. The narrower the track pitch, the more difficult it becomes to compress this eccentricity with the feedback loop alone. In this case, if the outer peripheral surface of the disc is precisely surface-finished in advance and a sensor for measuring the radial position variation of the outer peripheral surface is provided, the followability by feedforward can be improved as in the previous embodiments. .. In this case, the position of the disk in the circumferential direction may be arranged at substantially the same position as the magnetic head within a range that does not mechanically interfere with the magnetic head and the support mechanism. This eliminates the need for an operation and a circuit for compensating for the phase shift between the sensor and the magnetic head. The sensor that measures the outer peripheral surface of the disk has a detection resolution of 0.1 μm or less, a detection range of 10 μm or more, and a response frequency of 1 μm.
It suffices that the frequency is at least kHz, and for example, a linear displacement meter to which a magnetic resistance element is applied may be used.

In this embodiment, the rotation synchronization vibration caused by the eccentricity of the disk is detected by a relatively simple sensor, and the fluctuation of the track position caused by this vibration can be reduced. This is effective for an information recording device that is performed separately from the above, or a medium exchangeable information recording device.

Further, instead of measuring the radial position variation of the disk outer peripheral surface in the present embodiment, the same effect can be obtained by measuring the radial position variation of the track.

(Fourth Embodiment) FIG. 6 shows a block diagram of the fourth embodiment. In this embodiment, the track position detecting head and the driving mechanism in the first embodiment are arranged at a position facing the signal magnetic head and the driving mechanism. FIG. 7 shows an overall configuration diagram of the mechanical portion of this embodiment. When receiving a seek command from a host computer (not shown), the signal magnetic head is moved by the drive mechanism.

At this time, the reaction force of the acting force generated by the driving mechanism is received by the base 151 fixing the supporting member via the signal magnetic head supporting member 150 of the driving mechanism.
Since the base 151 is attached to the housing 153 of the computer by the vibration isolating support member 152, it has a natural frequency that is the mass of the disk device including this base and the spring constant of the vibration isolating support member 152. When the magnetic head is sought, this natural vibration mode is excited by the reaction force, and the base vibrates. This vibration may cause an error in positioning at the end of seek.

The difference between this embodiment and the first embodiment is that the first
In this embodiment, since the track position detecting head is also moved to the target track during seek, a reaction force is applied to the base when the detecting head is driven in the same manner. When the driving directions of the magnetic head and the position detection head with respect to the center of the disk are different, a complicated reaction force is applied to the base. The present embodiment relates to a structure for reducing such reaction force. That is, by arranging the respective drive mechanisms so that the reaction forces acting on the base by both drive mechanisms are opposite in direction on the same line of action, the forces acting on the base at the time of seek are canceled and become substantially zero. As a result, it is possible to provide an information recording apparatus that has both the effect of reducing the base vibration during positioning and the effect of reducing the rotation synchronous vibration after positioning.

(Fifth Embodiment) FIG. 8 shows a block diagram of the fifth embodiment. In the present embodiment, the track position variation is previously detected and stored, this value is read at the time of positioning, and is applied to the servo system as a feedforward signal as in the case of the first embodiment. Therefore, in this embodiment, the truck 3
An index signal 200 provided at one position on one circumference of the circuit, a signal generating means 201 for generating a signal each time the magnetic head 4 passes the signal 200, a position sensor 202 for detecting the displacement of the carriage 6, and a track position. A memory means 203 for storing the fluctuation is provided.

The operation method of this embodiment will be described with reference to the flow charts shown in FIGS. When the power of the magnetic disk device is turned on (F51), the rotation of the disk is started (F52) by the initial processing of the microprocessor and the startup of the spindle motor. When this initial processing is completed, the initial processing operation of the servo system is performed. Here, first, the magnetic head is sequentially moved and positioned on all the tracks or on a track at a certain interval if necessary (F5).
3). After the magnetic head 4 is positioned on the track 3 and the magnetic head 4 is controlled by the following servo system, the position of the sensor 202 attached to the carriage 6 is detected via the detection circuit 204 and the A / D converter 205. Read (F54), and the target value generating means 206 of the control system
Is input to and held as the target value (F55). Next, the control signal of this control system is changed to the position error signal 2 from the magnetic head 4.
07 to the signal 208 from the carriage position sensor,
Switching is performed by the switching circuit 209 (F56). At the same time, the position error signal 207 from the magnetic head 4 is input to the memory means 203 (F57). As a result, the magnetic head is held at a fixed position on this track by the fixed signal of the held position sensor regardless of the track position fluctuation, which means that the position drive of the track can be detected. To do.

Then, when the magnetic head detects the index signal 200 written on the track (F58), the position error signal 207, that is, the position fluctuation of the track from this point is fetched and stored in the memory means 203 (F5).
9). Since the signal stored at this time includes the asynchronous vibration between the magnetic head and the track, the position variation of the track synchronized with the rotation is averaged and extracted (F60).

This operation is repeated a necessary number of times, the obtained data is stored for each track number, and the operation is completed.
Upon completion, the following servo system controls the magnetic head again using the position error signal from the magnetic head (F
61). After that, a ready signal is issued to a host controller (not shown) to enable data reading and writing and wait for a command signal from the host.

When a seek command from the upper level is received (F6
2) Then, the magnetic head is moved and positioned to the target track (F63). When the magnetic head is positioned within a preset range (d in FIG. 10) of the center of the target track (F64), the servo system enters the following state (F65).

At this time, track variation information corresponding to the positioned track is read from the memory means (F66). When there is no data corresponding to the positioned track, the value of this track variation may be obtained by interpolation calculation from the information of the tracks before and after sandwiching this track (F67). When the head detects the index signal 200 (F68), from this time point, this information is input to the compensating element 21 of F = Gp- ¹ obtained by the equation 2 to obtain a feedforward signal (F69). The obtained signal is added to the positioning servo system of the magnetic head (F7
0). When the magnetic head is positioned within a preset range (e in FIG. 10) around the target track center, (F
71) and informs the host that signal recording / reproduction is possible (F72). Then, the data is read and written on the track, and the servo mechanism waits for the next command from the higher order.

In this embodiment, since the track position variation is obtained in advance, the track displacement variation can be corrected by the feedforward immediately after the seek, so that there is an effect that the data recording / reproducing start time can be shortened. Further, since a dedicated head for track detection is not required, there is an effect that it can be easily realized in terms of cost and mounting.

(Sixth Embodiment) FIG. 11 shows a block diagram of the sixth embodiment. In this embodiment, the displacement of the magnetic head is
This is a method that has a means for measuring separately from the position error signal, estimates the track position fluctuation by this means, and uses this estimated value. In FIG. 11, a semiconductor acceleration sensor 250 capable of detecting acceleration in the positioning direction is attached to a magnetic head, and the output of the acceleration sensor 250 is detected by a detection circuit 251, A.
The position information of the head is obtained by the position signal generating means, for example, the second-order integration circuit 253 via the / D converter 252. The track position fluctuation is estimated from the difference between this signal and the position error signal, and the obtained estimated signal is input to the feedforward compensator 21. A semiconductor acceleration sensor is disclosed in, for example, Japanese Patent Laid-Open No. 60-136972.

In this embodiment, the semiconductor acceleration sensor 250
The same effect as that of the first embodiment can be realized by attaching to the head. The integrator 253 is preferably implemented inside the microprocessor so as not to cause drift.

[0070]

As described above, according to the present invention, it is possible to provide an information recording / reproducing apparatus having a servo mechanism in which a head for signal reproduction can be positioned at high speed and with high accuracy in response to a track change of a disk.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a first embodiment of the present invention.

FIG. 2 is a block diagram of the servo system shown in FIG.

FIG. 3 is a flowchart illustrating the operation of the first exemplary embodiment of the present invention.

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

FIG. 5 is a configuration diagram of a third embodiment of the present invention.

FIG. 6 is a configuration diagram of a fourth embodiment of the present invention.

FIG. 7 is a configuration diagram of a mechanism unit according to a fourth embodiment of the present invention.

FIG. 8 is a configuration diagram of a fifth embodiment of the present invention.

FIG. 9 is a flowchart (No. 1) for explaining the operation of the fifth embodiment of the present invention.

FIG. 10 is a flowchart (No. 2) explaining the operation of the fifth embodiment of the present invention.

FIG. 11 is a configuration diagram of a sixth embodiment of the present invention.

[Explanation of symbols]

1 ... Disk, 2 ... Motor, 3 ... Track, 4 ... Magnetic head, 5 ... Arm, 6 ... Carriage, 7 ... Actuator, 8 ... Demodulation circuit, 10 ... Digital servo controller, 11 ... Servo system phase compensation calculator, 15 ... track position detection head, 21 ... feedforward compensator, 10
0 ... Sensor for measuring displacement of disk, 200 ... Index signal, 202 ... Position sensor, 203 ... Memory means, 250 ... Semiconductor acceleration sensor, 253 ... Position signal generating means.

Claims (14)

[Claims] 1. A rotating disk having a plurality of tracks on which signals are recorded, a signal recording / reproducing means which is movable on the surface of the disk to record or reproduce a disk signal, and the signal recording. In an information recording / reproducing apparatus having a control means for moving and positioning the reproducing means to an arbitrary track on the disc, a track for detecting the position fluctuation of the track before the signal recording / reproducing means detects the position fluctuation of the track. Information recording / reproducing, comprising position detecting means and means for adding a signal corresponding to the track position fluctuation detected by the track position detecting means to the control means so as to cancel the track position fluctuation. apparatus. 2. The information recording / reproducing apparatus according to claim 1, wherein a means for measuring a detection time difference between position signals detected by the track position detecting means and the signal recording / reproducing means, and a means for storing the detection time difference. An information recording / reproducing apparatus comprising: 3. The information recording / reproducing apparatus according to claim 1, wherein the track position detecting means and the signal recording / reproducing means are arranged substantially opposite to each other on a straight line passing through the center of the disc. Playback device. 4. A rotating disk having a plurality of tracks on which signals are recorded, a signal recording / reproducing means which is movable on the surface of the disk to record or reproduce the disk signal, and the signal recording. In an information recording / reproducing apparatus having a control means for moving and positioning the reproducing means to an arbitrary track of the disc, the positional fluctuation of a specific track is detected before the signal recording / reproducing means detects the positional fluctuation of the track. Information recording comprising: track position detecting means; and means for adding a signal corresponding to the track position fluctuation detected by the track position detecting means to the control means so as to cancel the track position fluctuation. Playback device. 5. The information recording / reproducing apparatus according to claim 4, wherein a means for measuring a detection time difference between position signals detected by the track position detecting means and the signal recording / reproducing means, and a means for storing the detection time difference. An information recording / reproducing apparatus comprising: 6. The information recording / reproducing apparatus according to claim 4, wherein the track whose position is detected by the track position detecting means is an inner track of the disc. 7. A rotating disk having a plurality of tracks on which signals are recorded, a signal recording / reproducing means capable of moving the disk surface to record or reproduce a disk signal, and the signal recording. In an information recording / reproducing apparatus having a control means for moving and positioning the reproducing means to an arbitrary track on the disc, the signal position recording / reproducing means detects the position variation of the track before the position variation of the disk in the radial direction is detected. Disc position fluctuation detecting means for detecting, and means for adding a signal corresponding to the radial position fluctuation of the disk detected by the disk position detecting means to the control means so as to cancel the radial position fluctuation of the disk. An information recording / reproducing apparatus comprising: 8. The information recording / reproducing apparatus according to claim 7, wherein the disk position variation detecting means is arranged so as to measure the variation of the outer peripheral surface of the disk. 9. The information recording / reproducing apparatus according to claim 7, wherein the disc position detecting means and the signal recording / reproducing means are arranged at substantially the same position in the circumferential direction of the disc. Playback device. 10. A rotating disk having a plurality of tracks on which signals are recorded, a signal recording / reproducing means which is movable on the surface of the disk to record or reproduce a disk signal, and this signal recording. In an information recording / reproducing apparatus comprising a control means for moving and positioning the reproducing means to an arbitrary track of the disc, a memory means for storing the position variation of the track, and the target track among the contents of the memory in the control means. An information recording / reproducing apparatus comprising: a unit for reading the position variation data corresponding to the above item; and a unit for adding the read data to the control unit. 11. The information recording / reproducing apparatus according to claim 10, wherein the position detecting means for detecting a displacement of a supporting member for supporting the signal recording / reproducing means and the signal recording / reproducing means are positioned on a target track. Means for holding the position information of the position detecting means after positioning and using this as a target signal, and switching for switching the control amount of the control means for positioning the signal recording / reproducing means to the output of the position detecting means. An information recording device comprising: 12. The information recording / reproducing apparatus according to claim 10, wherein said memory means is means for storing positional fluctuations of all tracks on the disk. 13. The information recording / reproducing apparatus according to claim 10, further comprising an interpolation calculation means for performing an interpolation calculation when a target track and a memory track are different from each other, and the memory means is a track position for each predetermined interval of the disk. An information recording device characterized by being a means for storing fluctuations. 14. A rotating disk having a plurality of tracks on which signals are recorded, a signal recording / reproducing means capable of moving the disk surface to record or reproduce a disk signal, and this signal recording. In an information recording / reproducing apparatus comprising a control means for moving the reproducing means to an arbitrary track of the disc and positioning it, an acceleration detecting means provided at a tip portion of the signal recording / reproducing means,
Means for obtaining the position signal of the signal recording / reproducing means from the output signal of the acceleration detecting means, and track detected by the position signal of the signal recording / reproducing means and the signal recording / reproducing means obtained from the output signal of the acceleration detecting means. A means for obtaining a signal corresponding to the track position variation from the difference from the position signal, and means for adding a signal corresponding to the track position variation to the control means so as to cancel the track position variation. Information recording / reproducing device.