JPH08315531A - Head positioning method and servo information writing method on disk-shaped recording medium, magnetic disk device, servo information writing device for magnetic disk device, displacement detection mirror - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a servo information writing method and the like that enables high-quality servo information writing by positioning a head with high accuracy even when vibration is applied to a carriage. A cylinder mounted on a slider 2 for displacement between an optical head 12 accurately positioned above a disk 1 of a magnetic disk device by an optical head positioning device 13 and a slider 2 having a head for writing servo information. It is amplified by a target 16 composed of a circular mirror and detected by a displacement detection circuit 14, and a VCM control circuit 6 drives and controls a VCM 5 according to the value of the detected displacement Xd and moves a carriage 4 to move a slider 2 to an optical head 12. And the head on the slider 2 is positioned.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for positioning a head on a disk-shaped recording medium and a servo information writing method in a magnetic disk apparatus and the like, and a magnetic disk apparatus and servo information writing for a magnetic disk apparatus using the method. The present invention relates to a device and a displacement detecting mirror for the device.

[0002]

2. Description of the Related Art In a magnetic disk apparatus, servo information, which is a mark for eliminating a radial deviation from a track of a magnetic disk, which is a disk-shaped recording medium, is used to position a head on a target track. .
Such servo information is generally written from the outside using a head of a device called a servo track writer, or is written using the head of the magnetic disk device itself. In recent years, with the increase in recording density of magnetic disk devices, the data surface servo method in which servo information is written on a part of the data surface has become mainstream, rather than the servo surface servo method having a disk surface dedicated to servo information. Therefore, the servo information is normally written by the latter method.

Further, particularly in the case of a small magnetic disk, due to the problems of space and impact resistance, when driving the carriage for carrying the head and the slider equipped with the head to an arbitrary position, the carriage is rotated around a rotation axis. A rotary type actuator is used. Positioning of the head at the time of writing the servo information, the position of one point of the carriage is detected by a high-resolution laser length meter,
This is done by driving the actuator so that it coincides with the target position.

By the way, in order to measure the position with such a laser length meter, a mirror for reflecting the laser beam is installed at the measuring point. The installation of this mirror lowers the mechanical resonance frequency of the actuator, and further adds the mechanical resonance generated at the mirror mounting portion, which necessitates lowering the zero-cross frequency of the positioning servo system. Deteriorated the positioning accuracy of the head. On the other hand, if the band width of the positioning servo system is wider, it is possible to control vibration of a higher frequency.

Furthermore, another actuator and a laser length measuring device are provided outside, and the external actuator and the internal actuator are connected to each other. By positioning the external actuator with the laser length measuring device, the head is moved to a predetermined position. In the positioning of the head by the external driving method, the significant deterioration of the mechanical resonance characteristic due to the external actuator and its connection is a more serious problem.

As to the deterioration of the mechanical resonance characteristic of such an actuator, for example, as described in Japanese Patent Laid-Open No. 5-274833, an optical head mounted on a rotary encoder and an optical disk plate formed on a head rotation support mechanism. A method of detecting the relative displacement between the head rotation support mechanism and the rotary encoder and positioning the head rotation support mechanism so as to keep the value of the relative displacement constant is proposed.

[0007]

The vibration caused by the spindle motor for rotating the magnetic disk is transmitted to the rotary shaft of the carriage and vibrates the slider including the carriage and the head. In the conventional head positioning method, however, the position measurement point of the carriage is controlled to stand still at the target position even with such vibration. Therefore, the vibration transmitted from the rotary shaft of the carriage is transmitted with the position measurement point of the carriage that is stationary as a fulcrum, and the head vibrates without stopping. When the head vibrates, the position of the servo information to be written shifts. That is, if the track is positioned by such servo information, the interval between the adjacent tracks is not constant, and there is a possibility that a data reproduction error occurs due to the interference of the data on the adjacent tracks. Further, it is expected that the track interval will become narrower with the future increase in recording density in the magnetic disk device.
It becomes a more important issue.

By the way, the vibrations transmitted to the head have opposite phases or are amplified depending on the position of the position measurement point of the carriage, and become smaller as the measurement point is closer to the head. Therefore, in the method of attaching the optical disc plate as in the above-mentioned conventional technique, the mechanical resonance characteristic is deteriorated, which makes it difficult to install the optical disc plate near the head. Further, if the optical disc plate is made smaller and lighter in order to prevent the mechanical resonance characteristic from deteriorating, processing of the optical disc plate, a mounting method, a mounting accuracy, etc. become problems. In addition, in order to detect the displacement with high accuracy by combining the optical disc plate and the optical head, it is necessary to shorten the distance between the optical head and the optical disc plate, however, it is difficult to actually arrange the optical head. is there.

In view of the above problems in the prior art, an object of the present invention is to position the head at a fixed position without deteriorating the mechanical resonance characteristics of the actuator, and even when vibration is applied to the carriage from the outside. A head positioning method and a servo information writing method on a disk-shaped recording medium capable of writing high-quality servo information, a magnetic disk device and a servo information writing device for a magnetic disk device using the method, and It is to provide a displacement detecting mirror for such a device.

[0010]

In order to achieve the above object, according to the present invention, first, an optical head which can be positioned with high accuracy is positioned above a rotating disk-shaped recording medium, and the optical head with respect to the optical head is positioned. While detecting the relative position,
A head positioning method for positioning a slider having at least a head capable of writing information to the disk-shaped recording medium while moving the slider to the surface of the disk-shaped recording medium, the slider and the optical head Is optically coupled, the amplified displacement between the optical head and the slider caused by the optical coupling is detected, and the detected and amplified displacement causes the head to perform the disk-shaped recording. A method of positioning a head on a disk-shaped recording medium for positioning on the medium is proposed.

According to the present invention, a slider equipped with a head movably supported by a carriage on a rotating disk-shaped recording medium is positioned by a carriage driving means, and the head rotates to rotate the disk-shaped recording medium. In at least the servo information writing method for writing servo information, the slider or the carriage is provided with a reflecting means having a reflecting surface, and the optical head is accurately positioned with respect to the disk-shaped recording medium.
The light from the optical head is reflected by the reflecting means, the amplified displacement between the optical head and the head is detected by the angle change of the reflected light, and the detected amplification between the optical head and the head is detected. There is proposed a servo information writing method in which the head is positioned by the applied displacement and servo information is written in the rotating disk-shaped recording medium.

Further, in order to achieve the above object, a magnetic disk device for writing servo information on a rotating disk-shaped recording medium by positioning a head by the above-described servo information writing method, which is a rotating disk. Recording medium, a slider provided with a head capable of writing information on the disc-shaped recording medium, and a carriage driving means for positioning the head while driving a carriage that moves the slider to the surface of the disc-shaped recording medium. An optical head that is provided outside of the magnetic disk device and that can be positioned with high precision with respect to a rotating disk-shaped recording medium of the magnetic disk device, at a part of the slider or the carriage driving means. A magnetic disk device provided with means for optically coupling between That.

Further, according to the present invention, a rotating disk-shaped recording medium, an optical head capable of highly accurate positioning,
An optical head positioning device for positioning the optical head above the disc-shaped recording medium, a slider having at least a head capable of writing information on the disc-shaped recording medium, and the slider on the surface of the disc-shaped recording medium. A magnetic disk drive comprising: a carriage drive unit for positioning a head while driving a moving carriage, and detecting the relative position between the optical head and the slider to position the head on the disk-shaped recording medium. At least one of the optical head or the optical head positioning device, and at least one of the slider or the carriage drive means is provided with a target having a curved reflective surface, and the target has a reflective surface. The optical head and the scan are reflected by the reflected light. Magnetic disk device provided with a means for detecting the relative position error between Ida is proposed.

Furthermore, according to the present invention, there is provided a servo information writing device for a magnetic disk device, which positions the head by the above-mentioned servo information writing method and writes servo information on a rotating disk-shaped recording medium of the magnetic disk device. Accurately positioning the rotating disk-shaped recording medium of the magnetic disk device, and optically amplifying the amplified displacement from the head via a slider of the magnetic disk device or a reflecting means of a carriage. Servo information for a magnetic disk device, including an optical head having a displacement detecting means for detecting and a means for outputting the detected displacement from the displacement detecting means of the optical head to a means for controlling the position of the head of the magnetic disk device. Writing devices have been proposed.

In addition, according to the present invention, for use as the optical coupling means of the magnetic disk device of the present invention, the target of the magnetic disk device, or the curved reflecting surface of the servo information writing device for the magnetic disk device. Of the displacement detecting mirror, which is formed by processing a reflecting film on the surface of a glass tube or a glass rod.

[0016]

According to the present invention described above, an optical coupling means, more specifically, between the slider on which the head of the magnetic disk device is mounted and the optical head for accurately positioning the head above the disk-shaped recording medium, A target having a curved reflecting surface is provided in the optical path formed between them, and the displacement of the slider is detected from the amplified angle change of the reflected light of the light incident from the optical head. The displacement of the head can be detected with high accuracy from a distant position without deteriorating the resonance characteristics, and the head can be accurately positioned without a position detection error due to the disturbance displacement transmitted to the carriage.

Further, according to the present invention, the inclination of the angle between the light incident on the target, which is the optical coupling means, from the optical head and the moving surface of the slider or the inclination with respect to the moving surface can be detected. Therefore, by controlling the inclination of the optical head so as to correct this, an error in the detected displacement due to the inclination of the optical axis of the optical head can be prevented, and the head can be accurately positioned.

Further, by inputting the movement information of the optical head or the disk-shaped recording medium to the carriage driving means as feedforward information, the carriage can be made to follow the optical head in a stable manner.

[0019]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. First, FIG. 1 shows the structure of a so-called servo track writer which is a servo information writing device in a magnetic disk device according to an embodiment of the present invention. In FIG. 1, reference numeral 1 is data information and servo information. Is a recording medium in which is written,
Reference numeral 2 denotes a disk in which a plurality of magnetic recording disks are stacked and held, reference numeral 2 denotes a slider on which a write head for writing at least servo information is mounted on the disk 1, and reference numeral 3 denotes the slider 2 as a disk. Reference numeral 4 denotes a load arm to be pressed against the carriage 1, reference numeral 4 denotes a carriage for supporting the slider 2 via the load arm 3, and reference numeral 5 denotes a carriage for driving the carriage 4 and VCM (voice coil). Motor), code 6
Is a VCM for controlling the drive current i of the VCM 5 according to the value of the displacement Xd detected by the displacement detection circuit described later.
A control circuit, reference numeral 7 is a servo information writing circuit for writing servo information on the disk 1 using the head on the slider 2, and reference numeral 8 is a spindle for stacking and holding the plurality of disks 1. Reference numeral 9 is a spindle motor for rotating the spindle 8, and reference numeral 10 is
Reference numeral 11 denotes a spindle motor drive circuit for driving the spindle motor 9 at a constant rotation, reference numeral 11 denotes an MPU (microprocessor) for controlling the entire operation, reference numeral 12 denotes an optical head for detecting the displacement of the slider 2. Thirteen
Is an optical head positioning device for moving and accurately positioning the optical head 12, and reference numeral 14 is the optical head 1
Reference numeral 15 denotes a displacement detection circuit for detecting the displacement Xd from the output of 2, and reference numeral 15 denotes a clock head for generating a clock serving as a reference when writing servo information.

In the above structure, the plurality of disks 1 are stacked and held by the spindle 8, and the spindle 8 is rotated by the spindle motor 9. The spindle motor 9 is driven by a spindle motor drive circuit 10 and is thus kept at a constant rotation speed. In addition, the slider 2
Are supported by the carriage 4 via the load arm 3 and move on the disk 1 by driving the carriage 4 by the VCM 5. Further, the servo information is as follows:
On the topmost disc, on the other hand, in case of the data surface servo system, it is written on all of them. In addition, the slider 2 provided with the above-mentioned write head is
Of course, it may be possible to read or erase these while writing the data information including the servo information.

Further, the optical head positioning device 13 is capable of highly accurate positioning using a so-called laser length measuring device or the like, and the optical head 12 is on the same rotation axis as the slider 2 and on the same radius. Is moved so that it is accurately positioned at a predetermined position.

Next, as shown in FIG.
The so-called target 16
Is attached, and the position of this target 16 is
It is detected by the optical head 12 described above. And FIG.
The displacement detection circuit 14 detects the relative displacement Xd between the optical head 12 and the slider 2 from the output of the optical head 12. Further, the VCM control circuit 6 shown in FIG. 1 controls the drive current i of the VCM 5 in accordance with the value of the displacement Xd, that is, the displacement Xd is zero (0), that is, the slider 2 moves to the optical head 12 described above. The write head on the slider 2 is positioned while driving the carriage 4 so that it is right below.

On the other hand, the clock head 15 first writes a clock signal of a constant frequency for one rotation outside the recording area of the disk 1 and reproduces the clock signal when writing servo information. That is, the servo information is written using the write head on the slider 2 with the slider 2 positioned at the target position. At this time, the servo information writing circuit 7 of FIG. The servo information is written in synchronization with the clock signal reproduced by the head 15. The MPU 11 controls the entire servo track writer.

FIG. 3 shows a flow chart of a procedure for writing servo information, where each step is abbreviated by an initial "S". First, an HDA (head disk assembly) is installed on the servo track writer shown in FIG. 1 (S1). Next, a command is sent to the spindle motor drive circuit 10 to activate the spindle motor 9, wait until the number of revolutions stabilizes (S2), and the clock signal is written by the clock head 15 for one revolution (S3). Then, the slider 2 is pressed against an outermost stopper (not shown) to be fixed (S4), and the optical head 12 is moved to above the slider 2 (S5). Then, in that state, the servo pull-in of the carriage 4 is performed (S6), whereby the slider 2 follows the optical head 12. Then, when the slider 2 enters the follow-up state, the optical head 12 is moved to a predetermined servo information writing position at a speed and an acceleration so that the follow-up is not lost (S7). Then slider 2
Is positioned and a command is sent to the servo information writing circuit 7 to repeat the position settling of the optical head 12 and the carriage 4 (in the case of “N” in S71), and after these position settling is performed (“Y” in S71). In the case of), clock head 15
The servo information is written to the disk 1 in synchronization with the clock signal reproduced in step S8 (S8), and when the writing of the servo information for one track is completed, the completion of the writing of the previous servo information is determined (S81). In this way, the positioning of the slider 2 and the writing of servo information are repeated (in the case of "N" in S81), and the spindle motor 9 is stopped (in the case of "Y" in S81) with the servo information written in all the tracks (in the case of "Y" in S81). S9), the writing of servo information is completed.

According to the structure of the servo information writing apparatus as shown in FIG. 1 according to the present invention, the optical head 12 is accurately positioned and the carriage 4 is driven so that the slider 2 follows the optical head 12. By positioning the drive head on the slider 2, the mechanical resonance characteristic of the actuator is not deteriorated, and the write head on the slider 2 can be positioned at a fixed position even if vibration is applied to the carriage 4, and thus high quality servo information can be obtained. Writing is possible. This will be specifically described below.

Referring again to FIG. 2, FIG. 2 is a diagram showing an example of the relationship between the target 16 mounted on the slider 2 and the optical head 12. In this figure, the optical head 12 is Laser light is emitted toward the target 16 and the reflected light is received to receive the target 16
And the relative displacement Xd of the optical head 12 is detected. As this target 16, for example, a cylindrical mirror is attached with the axial direction of the cylinder aligned with the radial direction of the rotational movement of the slider 2 so as to detect the displacement Xd by the so-called optical leverage displacement detection method. To do.

FIG. 4 shows the principle of displacement detection by the optical lever displacement detection method described above. In the figure, the horizontal movement Pt of the cylindrical mirror 16, which is the target, changes the reflection angle of the laser light incident from the vertical direction, causing a displacement Pb of the reflected light at the sensor position. As the cylindrical mirror 16, for example, a cylindrical or cylindrical surface having a smooth surface, which is mirror-processed, is used. Assuming that the radius of the cylindrical mirror 16 is r and the distance (lever length) from the reflecting surface of the laser light to the sensor is L, the following relationship is established in a range where the displacement Pt of the cylindrical mirror 16 is very small.

[Equation 1]

That is, the displacement Pt of the cylindrical mirror 16 can be amplified and detected by selecting the values of the radius r of the cylindrical mirror 16 and the lever length L. For example, r = 1 mm, L
= 50 mm, the displacement Pb is magnified about 100 times. Therefore, if the displacement resolution of the sensor is 0.1 μm, the displacement detection resolution of the cylindrical mirror 16 is 1 nm, and highly accurate displacement detection is possible. In this displacement detection method, it is not necessary to narrow down the laser beam unlike the displacement detection method for general optical discs, so a lens with a long focal length can be used, and the target 1 including the optical head 12 and the cylindrical mirror described above can be used.
Since the interval (work distance) of 6 can be lengthened, operability is improved.

Such an optical lever displacement detection method is used, for example, in a scanning tunneling microscope (STM). In STM, a two-dimensional displacement is detected by using a hemispherical mirror as a target. In this embodiment,
A cylindrical mirror is used as the target 16 for the purpose of allowing a one-dimensional displacement detection and allowing an error in the mounting position of the target in the radial direction. Such a cylindrical mirror only allows positional deviation between the cylindrical mirror 16 and the optical head 12 due to HDA component accuracy, assembly accuracy, cylindrical mirror mounting accuracy, etc. when the HDA is installed on a servo track writer. Length is required. However, the HDA is generally made with high precision, and the length of the cylindrical mirror 16 may be about 1 mm, for example. When the cylindrical mirror 16 is made of glass, r = 1 m
If m, the mass will be 0.05 g or less, including the adhesive for mounting, and the mechanical resonance characteristics of the actuator will hardly be deteriorated.

FIG. 5 is a view showing an example in which the target 16 composed of the cylindrical mirror is mounted on the load arm 3 holding the slider 2 instead of the slider 2. In recent years, in response to lower flying height of the slider 2,
The shape of the slider 2 tends to be small, and it may be impossible to secure a space for mounting the target 16. In such a case, as shown in FIG. 5, the target 16 may be attached at a position close to the head above a member supporting the slider 2 such as the load arm 3. Further, instead of the above structure, as shown in FIG.
The target 16 can be attached to a portion such as the carriage 4 that operates in conjunction with the slider 2.

As such a target 16, for example, a glass tube or rod having a smooth surface and having a mirror coating such as a metal film may be used.
Further, since the position of the slider 2 is controlled so that the laser light is incident on a specific position of the target 16, the accuracy of the curvature (radius) of the reflecting surface thereof may be within several%, and a general inexpensive glass tube. It is also possible to use Therefore,
As described above, the target 16 is extremely lightweight and inexpensive, does not need to be removed and reused, and can be attached as it is, which improves workability.

Further, FIG. 7 shows another example of the shape of the target 16 described above. As also shown in this figure, the target 16 may use a part of a cylinder (FIG. 7A) or a cylinder (FIG. 7B), and in that case, the weight can be further reduced. For example, a part of the glass tube may be used, or a resin may be pressed to form a part of the cylinder. As the reflective surface, not only the above convex surface,
A concave surface may be used (FIGS. 7 (c) and (d)). Also,
The curvature of the reflecting surface does not have to be constant, and for example, the cross-section may have an elliptic curvature changing shape (FIG. 7E). Furthermore, when the mounting accuracy of the target 16 is sufficiently secured, the sphere or a part thereof (see FIG.
(F)) may be used as the target, in which case
The curvature does not have to be constant. Further, the reflecting surface does not have to be a surface, and may be one that reflects inside the target 16. That is, the target 16 may be any target as long as it can convert the displacement in the horizontal direction into the reflection angle of the laser beam, and the slider 2, the load arm 3, the carriage 4, etc.
The curved surface or the mirror may be directly processed to form the reflecting surface.

Next, FIG. 8 shows an example of an optical system adopted in the optical head 12 described above. In this embodiment, the laser light emitted from the laser diode (LD) 18 is condensed by the objective lens 19 and is incident on the cylindrical mirror 16 which is the target. This cylindrical mirror 16
The reflected light of the laser light by the beam splitter 20
The light is dispersed by and is incident on the photodetector (PD) 21, whereby the displacement is detected.

The PD 21 is divided into two parts, and detects the displacement by the difference between the outputs of the PDs. FIG. 9A shows the structure of the divided PD. 9B shows the relationship between the displacement Pb and the displacement output Xd of the incident laser spot 22 (the hatched portion in FIG. 9A). Here, the displacement output Xd from the displacement detection circuit 14 in the figure is expressed as follows.

[Equation 2] In this mathematical expression, A and B represent respective outputs from the PD 21 divided into two.

The reflecting surface is vertically displaced from the focal position (focus offset) due to the precision of HDA components, the precision of assembly, the precision of mounting the target 16, and the like.
In this case, since the diameter of the beam spot 22 on the PD 21 changes, the displacement detection sensitivity of the optical head 12 changes. If the displacement detection sensitivity changes by ± 15% or more, the following may not be performed normally. Therefore, if there is such a possibility, the optical head 12 is once moved on the target 16 while the slider 2 is fixed at the outer or inner position, and the displacement detection sensitivity is detected and corrected. By doing so, such a problem can be solved.

However, a large change in the displacement detection sensitivity may reduce the displacement detection accuracy. Further, dynamic fluctuation of the displacement detection sensitivity is not preferable because it causes disturbance of the displacement detection signal. In such a case, it is necessary to provide the optical head with a focus control mechanism, perform autofocus control to keep the diameter of the beam spot 22 at the sensor position constant, and make the sensor detection sensitivity constant.

Next, in FIGS. 10A and 10B, a structure of a PD having a four-division structure for outputting the Af signal for performing the autofocus control at the same time as the displacement output Xd, Also, the relationship between the displacement Pb of the beam spot 22 which is the reflected laser light and the displacement output Xd is shown. In this case, the detected displacement Xd and the autofocus signal Af are as follows.

(Equation 3)

[Equation 4] In these equations, A, B, C and D represent the respective outputs from the PD 21 divided into four.

FIG. 11 shows another embodiment of the optical system of the optical head 12. In the optical system according to the other embodiment, the laser light emitted from the LD 18 is once collimated by the collimator lens 24, condensed by the objective lens 19, and incident on the cylindrical mirror 16 as a target. The reflected light of the laser light from the cylindrical mirror 16 is returned to parallel light by the objective lens 19,
The light is split by the beam splitter 20 and is incident on the position detection element (PSD) 23. In order to reduce the diameter of the beam spot 22 incident on the PSD 23,
A diaphragm 25 is arranged between the collimator lens 24 and the beam splitter 20. In such a configuration,
The length L of the optical lever is the distance from the reflecting surface of the cylindrical mirror 16 to the objective lens 19.

12 (a), (b) and (c), the structure of a position detecting element (PSD) 23 used as a sensor for detecting the beam spot 22 in place of the above-mentioned PD,
The sensor output of the PSD 23 and the relationship between the displacement Pb of the beam spot and the displacement output Xd are shown. This P
The SD 23 is a sensor capable of detecting the center position of the beam 22 regardless of the intensity or diameter of the beam 22,
There are a type that detects a one-dimensional position with a single sensor and a type that detects a two-dimensional position. Since the one-dimensional displacement detection is sufficient in the present embodiment, only the one-dimensional PSD is used in the following description, but it is needless to say that the two-dimensional PSD can be used instead. Yes.

This PSD 23 is basically the above PD.
It is made of the same material as the (photodetector), and one element has two output terminals. The photoelectric conversion sensitivity of the output from each output terminal is linear with respect to the position from the output terminal, and as is clear from FIG. 12B, zero (0) at the position farthest from the output terminal, The maximum value is at the closest position, and is 1/2 the maximum value at the center. Therefore, the displacement output Xd with a constant detection sensitivity is always obtained from the outputs I1 and I2 from these two output terminals, regardless of the intensity and the beam diameter of the beam spot 22 by performing the calculation represented by the following formula. Obtainable.

(Equation 5) As described above, by using the PSD instead of the PD as the sensor, the displacement detection sensitivity can be kept constant without performing focus control, and thus stable displacement detection can be performed with a simple configuration.

FIG. 13 shows still another embodiment of the optical system of the optical head 12. In this embodiment, the laser light emitted from the LD 18 is once condensed by the objective lens 19 and then made into a very thin parallel light by the collimator lens 24, and is incident on the cylindrical mirror 16 which is a target. The reflected light of the laser light from the cylindrical mirror 16 is split by the beam splitter 20 and is incident on the PSD 23 as well. Further, in order to narrow the beam, as in the example shown in FIG.
5 may be arranged. In this configuration, even if the reflection position of the cylindrical mirror 16 fluctuates up and down, the diameter of the beam spot 22 at the position of the PSD 23, which is a sensor, hardly changes. Therefore, even if the PD 21 is used as the sensor, the displacement detection sensitivity is increased. Does not fluctuate. Here again, the length L of the optical lever is the distance along the optical path from the reflecting surface of the cylindrical mirror 16 to the PSD 23.

Further, FIG. 14 shows an example of the configuration of the optical head 12 having a tilt correction mechanism. That is, the tilt correction mechanism 26 is inserted and arranged between the optical head 12 and the optical head positioning device 13, and corrects the tilt of the beam from the optical head 12 and the tilt of the target 16.

In such a structure, when the beam of the optical head 12 is not vertically incident on the moving surface of the target 16, the vertical movement of the target 16 (movement in the focus offset direction) leaks into the displacement signal Xd. That is, when the beam inclination is θ and the vertical displacement of the target 16 is Xh, the displacement detection error Ed generated by the vertical movement of the target 16 is given by the following mathematical expression.

(Equation 6)

In this way, the detected displacement detection error Ed
Since the static component of is an overall offset, it does not affect the servo signal writing accuracy. However,
The dynamic component is directly written as a vibration component in the servo signal. Specifically, the slider 2 is the disk 1
When the target 16 is attached to the slider 2 or the load arm 3, the above displacement detection error E
The dynamic component of d is generated. Therefore, when the beam inclination θ cannot be suppressed to be sufficiently small, the inclination correction mechanism 26 described above is necessary to correct the beam inclination.

FIG. 15 shows a method of correcting the tilt of the beam by the above tilt correcting mechanism 26. For example, in the vicinity of the target 16 on the slider 2, the target 16
The reflecting surface P of a plane parallel to the moving direction (see the arrow in the figure) is configured. Spindle 8 that rotates the disk 1
With the stationary state, the laser beam from the optical head 12 is incident on the reflecting surface P, and the reflected light is incident on the center of the PSD 23 so that the displacement signal Xd becomes zero. Tilt the head 12. When the beam inclination θ and the displacement Xh of the target 16 (see the arrow Xh in the figure) can be measured, the displacement detection error Ed may be corrected by calculation.

Further, in FIG. 16, α of the target 16 is
The structure and method of correcting the inclination of a direction are shown. In the figure, if the target 16 is mounted so as to be tilted, the reflected light of the laser light may be dislocated from the sensor (for example, the PD 21 or PSD 23) of the optical head 12. By the way, of the inclinations of the target 16, the inclination of the target 16 within the moving plane has a relatively small effect, and therefore the necessity of correction is small. However, with respect to the moving surface of the target 16, the target 16
When the is attached with being inclined in the α direction, the inclination needs to be corrected. Therefore, similarly to the above, the tilt adjusting mechanism 26 inserted and arranged between the optical head 12 and the optical head positioning device 13 rotates the optical head 12 in the direction of the arrow in the figure to change the tilt α with respect to the target 16. Thus, the correction can be performed by adjusting the inclination of the optical head 12 so that the output value of the PSD 23 of the optical head 12 becomes maximum.

Further, as shown in FIG. 17, the optical head 12
By lengthening the beam spot 22 of the target 16 in the axial direction of the target 16, even if the target 16 is tilted to some extent, it is reflected by the target 16 and the PSD 23
It is also possible to lengthen the beam spot 22 incident on the top so that a part of the beam spot 22 is surely incident on the PSD 23. Therefore, according to such a configuration, the target 16
It is possible to widen the allowable range of the attachment angle of the target 16 without correcting the inclination of the target 16. The vertically long beam as described above can be easily formed, for example, by making the shape of the diaphragm 25 vertically long.

Next, in FIG. 18, unlike the structure of the optical head described above, a target 16 composed of a cylindrical mirror, which is an optical lever, is arranged inside the optical head, so that an optical head equipped with a displacement amplification mechanism is provided. 12 'shows an example of 12'.
Further, in this embodiment, instead of the above-mentioned cylindrical mirror, a plane mirror 27 is attached to the slider 2 at an angle of 45 ° so that the laser light incident from the horizontal direction is reflected in the vertical direction.

According to this structure, when the slider 2 is displaced in the horizontal direction, the reflection position of the laser light from the LD 18 by the plane mirror 27 changes, so that the reflected light moves in parallel by the same distance as the displacement of the slider 2. To do. Therefore, the displacement of the reflected light is amplified by the optical lever or the cylindrical mirror 16 provided inside the optical head 12, thereby improving the displacement detection sensitivity of the PSD 23. At this time, when the rotary actuator is used, the slider 2 described above, that is, the plane mirror 27 mounted thereon rotates, so that the laser light incident part is also moved integrally with the optical head 12. . In addition,
In the case of this method, the same degree of sensitivity as that in the horizontal direction is required even with respect to the displacement of the slider 2 in the vertical direction.

Further, in FIG. 19, in the optical head 12 'in which the target 16 which is an optical lever is arranged, a rectangular mirror 28 is used instead of the above-mentioned plane mirror 27, and the beam incident from the vertical direction is used. Right angle mirror 28
A modified example in which the two reflected surfaces are reflected and the reflected beam is returned to the vertical direction again is shown. In the case of such a modified example, the displacement of the reflected light is amplified to twice the displacement of the slider 2. The reflecting surface of the right-angled mirror 28 is attached to the moving surface of the slider 2 at an angle of 45 °, and the laser light is applied to the slider 2.
When incident perpendicularly to the moving surface of the slider 2, the sensitivity does not occur with respect to the displacement of the slider 2 in the vertical direction. In other cases, the sensitivity to the displacement of the slider 2 in the vertical direction is generated depending on the mounting error of the right-angled mirror 28 and the degree of inclination of the incident laser light. Will be required.

In the optical head 12 'shown in FIGS. 18 and 19 in which the target 16 which is an optical lever is arranged, the plane mirror 27 or the right angle mirror mounted on the surface of the slider 2 is used. Instead of 28
For example, a right-angle prism or the like may be used, or a part of the slider 2, the load arm 3 holding the slider 2 or the carriage 4 for moving the slider 2 may be processed,
The reflecting surface may be directly formed on a part of them. Further, the angle formed by the reflecting surface of the plane mirror 27 or the right-angled mirror 28 and the moving surface of the slider 2 may not be 45 °, and instead of the right-angled mirror 28, the two reflecting surfaces may be other than 90 °. You may use the mirror which makes the angle of. In that case, the reflection direction of the laser light and the ratio of the displacement of the reflected light to the displacement of the slider change.

In the various embodiments of the present invention described above, the movement of the slider 2 from the track in which the slider 2 is present to the next track is performed by the slider 2 following the movement of the optical head 12. Therefore, the optical head 1
2, the movement of the slider 2 is delayed,
In some cases, the operation may become unstable.
Therefore, as shown in FIG. 1, the optical head positioning device 1
Movement information Sf such as speed and acceleration of the optical head 12 from 3
Is input to the VCM control circuit 6 as feedforward information, whereby the slider 2 is moved while driving the carriage 4. Therefore, according to such a configuration in which the movement information Sf of the optical head is feedforward, the movement of the optical head 12 is known in advance, so that the slider 2 can be made to follow stably.

Finally, FIG. 20 shows a modification in which a transparent window is provided in a part of the case of the magnetic disk device according to the present invention. In general, the magnetic disk device is extremely disliked by dust, and therefore, it is sealed in the case 29 during normal use. In addition, operations such as manufacturing a magnetic disk device and writing servo information are performed at a high cleaning cost.
It is being done inside the house. Therefore, in the magnetic disk device according to this modified example, the slider 2 is provided in the case 29.
By implementing a transparent window 30 made of, for example, glass in a range necessary to detect the target 16 mounted on the magnetic disk device, the magnetic disk device is sealed in the case 29. It becomes possible to position the head as in the example, which enables the writing of the servo information outside the clean room. In that case, for example, a fixed head is installed inside the magnetic disk device, and the fixed head is used as a clock head (see reference numeral 15 in FIG. 1) to generate a clock signal.

Although a laser diode (LD) is used as a light source in the optical head 12 in the above embodiment, however, this light source does not need to be a coherent light such as a laser beam, and instead of this, For example, a light emitting diode (LED) or the like may be used, and the light source is not limited to visible light, but may be infrared light or ultraviolet light. Further, an interference filter matched to the wavelength of the light used is provided with a photoelectric conversion sensor (the PD21 or PSD23 described above).
, Etc.), the influence of ambient light can be reduced.

In the above embodiment, the optical head 12 is moved to change the relative position with respect to the disc 1. On the contrary, the optical head 12 is fixed and the disc 1 side is moved. You may move it. Further, in the above embodiment, an example in which the cylindrical mirror 16 which is the target is left attached by an adhesive agent or the like is described. However, instead of this, a mechanism for attaching and detaching the cylindrical mirror 16 is provided. After writing the servo information, this may be removed.

In addition, according to the embodiment of the present invention described above,
In particular, by using the above-described PSD 23 as the photoelectric conversion sensor, the displacement detection sensitivity can be kept constant without the need for a focus mechanism, and thus the configuration of the optical head can be simplified. Further, as shown in FIG. 17 described above, by lengthening the beam spot in the axial direction of the target, it becomes possible to widen the allowable range of the mounting angle error of the target.

[0057]

As is apparent from the above detailed description, according to the present invention, an optical head capable of accurately positioning with respect to a magnetic disk on which servo information is written and a head for writing servo information are provided. By detecting the amplified displacement of the slider provided, it is possible to detect the displacement of the head with high accuracy, there is no position detection error due to the disturbance displacement transmitted to the carriage, and the accurate positioning of the head becomes possible. By detecting and correcting the inclination of the angle between the incident light and the moving surface of the slider and the inclination of the mirror with respect to the moving surface of the slider, errors in detection displacement due to the inclination of the optical axis of the optical head can be prevented and the head can be accurately measured. Positioning is possible, and further, movement information of the optical head or the disk-shaped recording medium is input to the carriage driving means as feedforward information. And by, that it is possible to stably follow the carriage in the optical head, it exhibits excellent effect also in the art.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a servo track writer for writing servo information by a head positioning method according to an embodiment of the present invention.

FIG. 2 is a partially enlarged perspective view showing a relationship between a target mounted on a slider and an optical head in the servo track writer.

3 is a flowchart showing an example of a servo information writing procedure in the embodiment shown in FIG.

FIG. 4 is an explanatory diagram showing the principle of a displacement detection method using a target in the above embodiment.

FIG. 5 is a diagram showing an example in which the target is mounted on a load arm of a magnetic disk device.

FIG. 6 is a diagram showing an example in which the target is mounted on a carriage of a magnetic disk device.

FIG. 7 is a perspective view showing an example of another shape of the target.

FIG. 8 is a diagram showing a configuration of an optical system of an optical head in the servo track writer of the above embodiment.

FIG. 9 is a diagram showing a configuration of a two-divided photodetector that receives a beam spot reflected by a target and outputs a displacement and a displacement output relationship thereof in the above embodiment.

FIG. 10 is a diagram showing a configuration of a four-division photodetector that receives a beam spot reflected by a target and outputs a displacement and a displacement output relationship thereof in the above embodiment.

FIG. 11 is a diagram showing another configuration of the optical system of the optical head in the servo track writer of the above embodiment.

FIG. 12 is a diagram showing a configuration of a position detection element that receives a beam spot reflected by a target and outputs a displacement and a displacement output relationship thereof in the above embodiment.

FIG. 13 is a diagram showing still another configuration of the optical system of the optical head in the servo track writer of the above embodiment.

FIG. 14 is a diagram showing an example of the configuration of an optical head further including an inclination correction mechanism.

FIG. 15 is a diagram illustrating the principle of a method for correcting the tilt of a beam in the configuration example of the optical head including the tilt correction mechanism.

FIG. 16 is a diagram showing an example of the configuration of an optical head including a correction mechanism for correcting the inclination of the target.

FIG. 17 is a diagram showing an example of another optical head in which the beam spot with which the position detecting element is irradiated is elongated vertically.

FIG. 18 is a diagram showing another configuration example in which a displacement amplification mechanism by an optical lever is provided inside the optical head.

FIG. 19 is a diagram showing still another configuration example in which a displacement amplification mechanism using an optical lever is provided inside the optical head.

FIG. 20 is a diagram showing an embodiment of a magnetic disk device in which a transparent window is provided in a part of the case.

[Explanation of symbols]

 1 Disk 2 Slider 4 Carriage 5 VCM 12 Optical Head 13 Optical Head Positioning Device 14 Displacement Detection Circuit 16 Target 18 Laser Diode 19 Objective Lens 20 Beam Splitter 21 Photodetector 22 Beam Spot 23 Position Detection Element 24 Collimator Lens 25 Aperture 26 Tilt Correction Mechanism

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Maruho Goto 2880 Kozu, Odawara City, Kanagawa Prefecture Storage Systems Division, Hitachi, Ltd. (72) Inventor Hidehiko Kando, 502 Jinritsucho, Tsuchiura-shi, Ibaraki Hiritsu Seisakusho Co., Ltd. In-house (72) Inventor Katsuhiko Kimura 502 Jinritsucho, Tsuchiura City, Ibaraki Prefecture

Claims (29)

[Claims] 1. An optical head that can be positioned with high accuracy is positioned above a rotating disk-shaped recording medium, and at least information is written to the disk-shaped recording medium while detecting a relative position to the optical head. A head positioning method of positioning a head while moving a slider having a movable head to the surface of the disk-shaped recording medium, comprising: the slider or a member that moves in conjunction with the slider; and the optical head. The optical displacement between the optical head and the slider or the member that moves in conjunction with the slider, which is generated by the optical coupling, is detected, and the detected amplified signal is amplified. A head on a disk-shaped recording medium, characterized in that the head is positioned on the disk-shaped recording medium by displacement. Positioning method. 2. The method for positioning a head on a disk-shaped recording medium according to claim 1, wherein the optical coupling between the slider or a member that moves in conjunction with the slider and the optical head comprises: A method for positioning a head on a disk-shaped recording medium, which utilizes reflection of light by a light reflecting surface. 3. The method of positioning a head on a disk-shaped recording medium according to claim 2, wherein the light reflection surface is a curved surface so that the optical head and the slider or the slider is moved in association with each other. A method for positioning a head on a disk-shaped recording medium, characterized by detecting an amplified displacement between the member and the member. 4. The method for positioning a head on a disk-shaped recording medium according to claim 1, wherein the amplified displacement between the optical head and the slider or a member that moves in association with the slider is increased. The detection is performed by detecting the displacement of light between the optical head and the optically coupled slider or a member that moves in conjunction with the slider and the optical head. Positioning method. 5. A slider equipped with a head movably supported by a carriage on a rotating disk-shaped recording medium is positioned by a carriage driving means, and at least servo information is written on the rotating disk-shaped recording medium by the head. In the servo information writing method, a reflecting means having a reflecting surface is provided on the slider or a member that moves in conjunction with the slider, the optical head is accurately positioned with respect to the disk-shaped recording medium, and the light from the optical head Is reflected by the reflecting means, an amplified displacement between the optical head and the head is detected by an angle change of the reflected light, and the head is detected by the detected displacement between the optical head and the head. Position and write servo information on the rotating disk-shaped recording medium. Servo information writing method comprising Mukoto. 6. The servo information writing method according to claim 5, wherein the carriage driving means positions the slider by maintaining the detected displacement between the optical head and the head at a predetermined target value. And a servo information writing method. 7. The servo information writing method according to claim 5, wherein a reflecting surface of the reflecting means provided on the slider or a member that moves in association with the slider has a curved surface. The servo information writing method is characterized by amplifying the displacement between the optical head and the head due to the change in the angle of the reflected light. 8. The servo information writing method according to claim 7, wherein the curved surface of the reflecting means is a cylindrical surface or a reflecting surface formed of a part thereof. 9. The servo information writing method according to claim 5, wherein the shape of the spot of the light incident on the reflecting means from the optical head is elongated in a direction orthogonal to the displacement detection direction. How to write servo information. 10. The servo information writing method according to claim 5, wherein movement information of the optical head or the disk-shaped recording medium is input to the carriage driving means as feedforward information to control movement of the carriage. A method for writing servo information, comprising: 11. The servo information writing method according to claim 5, wherein a displacement is amplified and detected from a change in a reflected light angle on a curved reflecting surface provided inside the optical head. Information writing method. 12. The servo information writing method according to claim 5, wherein the reflecting surface of the reflecting means is formed by processing a part of the slider or a member that moves in association with the slider. And servo information writing method. 13. The servo information writing method according to claim 5, wherein the reflecting means is formed of a separate member having a reflecting surface, and is attached to the slider or a member that moves in conjunction with the slider. How to write servo information. 14. The servo information writing method according to claim 13, wherein the reflecting means is attachable to and detachable from the slider or a member that moves in association with the slider. 15. A disk-shaped recording medium that rotates, a slider having a head capable of writing information on the disk-shaped recording medium, and a carriage that moves the slider to the surface of the disk-shaped recording medium while driving the carriage. A magnetic disk drive comprising: a carriage drive unit for positioning the head; and a slider or a member that moves in conjunction with the slider, provided with a light reflecting unit having a curved reflecting surface. 16. A rotating disk-shaped recording medium, a slider provided with a head capable of writing information on the disk-shaped recording medium, and a carriage for moving the slider to the surface of the disk-shaped recording medium while driving the carriage. A carriage drive unit for positioning the head, and a slider or a member that moves in association with the slider, which is disposed outside the magnetic disk device and which is a rotating disk-shaped recording medium of the magnetic disk device. On the other hand, a magnetic disk device is provided with a reflecting means for reflecting light from an optical head that can be positioned with high accuracy. 17. The magnetic disk device according to claim 16, wherein the reflecting surface of the reflecting means is a curved surface. 18. The magnetic disk device according to claim 17, wherein the reflecting means that is the curved surface has a cylindrical or a reflecting surface that is a part thereof. apparatus. 19. The magnetic disk device according to claim 16, wherein the magnetic disk device is provided in a housing, and a part of the housing is provided outside the magnetic disk device. A magnetic disk device characterized in that a window through which light can pass is provided for passing incident light and reflected light between an optical head and the reflection means. 20. The magnetic disk device according to claim 16, wherein the reflecting surface of the reflecting means is a flat surface. 21. The magnetic disk device according to claim 16, wherein the reflecting means is removable. 22. A slider provided with a head for writing servo information on a rotating disk-shaped recording medium of a magnetic disk device; a reflection means provided on the slider or a member that moves in conjunction with the slider; The magnetic disk device is equipped with a displacement detecting means capable of being accurately positioned with respect to the rotating disk-shaped recording medium and optically detecting an amplified displacement with the head by the reflected light from the reflecting means. A servo information writing device for a magnetic disk device, comprising: an optical head; and means for outputting the detected displacement from the displacement detecting means of the optical head to a means for controlling the position of the head of the magnetic disk device. . 23. The servo information writing device for a magnetic disk device according to claim 22, wherein the reflecting means has a curved reflecting surface. apparatus. 24. The servo information writing device for a magnetic disk device according to claim 22, wherein the reflecting means has a flat reflecting surface, while the optical head has a curved reflecting surface. A servo information writing device for a magnetic disk device, which is provided with a reflecting means. 25. The servo information writing device for a magnetic disk device according to claim 22, wherein the displacement detecting means is arranged at a position for receiving at least reflected light reflected by a reflecting surface of the reflecting means. A servo information writing device for a magnetic disk device. 26. The servo information writing device for a magnetic disk device according to claim 25, wherein the displacement detecting means is composed of at least two photodetectors that receive reflected light. Servo information writing device for magnetic disk device. 27. The servo information writing device for a magnetic disk device according to claim 25, wherein the displacement detecting means is composed of a position detecting element that changes an output depending on a position where the reflected light is received. A servo information writing device for a magnetic disk device. 28. The servo information writing device for a magnetic disk device according to claim 22, further comprising a tilt correction means for correcting the tilt of the optical head. apparatus. 29. The reflection means of the magnetic disk drive according to claim 17, or the reflection means according to claim 23 or 24.
A displacement detecting mirror for use as a curved reflecting surface of the servo information writing device for a magnetic disk device according to, characterized by being formed by processing a reflecting film on the surface of a glass tube or a glass rod. Displacement detection mirror.