JPH1038519A - Position detecting device and positioning device for rotary object, and information recording device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect the positional information of a rotary object by providing an interferometer which rotates around an axis of rotation which is nearly the same as that of the rotary object, and causing interference between the reflected light rays of a measuring luminous flux from the interferometer from the rotary object by the interferometer. SOLUTION: An optical non-contact distance sensor unit OPS is arranged on the outside of a hard disk driver HDD and can rotate around an axis of rotation which is nearly the same as that of a magnetic head arm ARM1 and, when the unit OPS rotates, the rotated position of the unit OPS is measured by means of a high-resolution rotary encoder RE having the same axis of rotation. The unit OPS projects a luminous flux upon the side face of the arm ARM1 and the reflected light of the luminous flux from the side face is converged into one interference luminous flux. A photoelectric element PD converts the bright-dark change of the luminous flux caused by the variation of the distance to the arm ARM1 into a sine wave electric signal and an electric circuit in the OPS divides one sine wave into several tens of phases and outputs the divided sine waves as high-resolution digital displacement signals. Therefore, the variation of the distance to the arm ARM1 can be detected from the displacement signals with resolution of about 0.01μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a position detecting device and a positioning device for a rotating object such as a magnetic head of a hard disk drive, and an information recording device using the same. The present invention particularly relates to an apparatus for manufacturing a hard disk drive (hereinafter referred to as an HDD) used in a computer,
The present invention can be suitably applied to a device for writing a servo track signal to a hard disk in a DD with high accuracy.

[0002]

2. Description of the Related Art FIG. 1 is an explanatory view of a conventional apparatus for writing a servo track signal to a hard disk in an HDD.

In FIG. 1, HDD is a hard disk drive, HD is a hard disk, SLID is a slider, AR
M1 is a magnetic head arm, VOIC is a voice coil, OHD is a hard disk HD spindle, OARM is a magnetic head arm
This is the rotation axis of ARM1.

[0004] A magnetic recording medium is deposited on the surface of the hard disk HD. The hard disk HD is constantly rotating at a high speed around the spindle OHD, and a magnetic head is arranged close to the surface of the hard disk HD. The magnetic head is built into a substantially rectangular parallelepiped called slider SLID attached to the end of arm ARM1 with rotation center OARM outside hard disk HD.
It is designed to be able to move relatively in the radial direction on the HD.

Thus, magnetic information can be written or read at an arbitrary position (track) on the surface of the disk-shaped hard disk by the rotating hard disk HD and the magnetic head moving in an arc.

The magnetic recording system on the surface of the hard disk HD is first divided into a plurality of annular tracks having different concentric circle radii with respect to the rotation center OHD of the hard disk. It is divided into a plurality of arcs, and is finally recorded and reproduced in a plurality of arc-shaped areas in a time series along the circumferential direction.

As a recent trend, there is a demand for an increase in the recording capacity of a hard disk, and there is a demand for increasing the density of information recorded on the hard disk. As a means for increasing the density of information recorded on a hard disk, it is effective to reduce the width of concentrically divided tracks to improve the recording density in the radial direction.

The recording density in the radial direction is represented by a track density per inch length TPI (track / inch).
It is about 00TPI. This means that the track spacing is about 3.125 microns.

In order to determine such a fine track pitch, the magnetic head is positioned in the radial direction of the hard disk HD at a resolution of about 1/50 of the track width (0.06 micron), and a servo track signal is written in advance. There is a need. The important technique here is to write servo track signals sequentially while performing high-resolution positioning in a short time.

FIG. 2 shows a schematic configuration diagram of a conventional positioning device for writing a servo track signal. In the figure, PROD is a push rod, ARM2 'is an arm for the push rod PROD, MO is a control motor for positioning, RE is a rotary encoder for detecting the amount of rotation of the rotation axis of the motor MO, and SP is a rotary encoder. MD is a signal processor that analyzes the detection output and issues a positioning command signal to the magnetic head servo track signal writing position.
This is a motor driver that drives the motor MO according to the SP command signal.

Conventionally, as shown in FIG. 2, a magnetic head arm ARM1 is pressed against the cylindrical surface of a push rod PROD from the side,
Rotating the arm ARM2 'with the motor MO while taking feedback control with the system of the rotary encoder RE, signal processor SP and motor driver MD, and push rod P
Positioning was performed while the ROD was sequentially finely fed, and servo track signals were sequentially written.

[0012]

Recently, assuming higher precision positioning, the movement of the magnetic head arm is measured with high precision by optical means without mechanically pressing the magnetic head arm. A way to do this has also been devised. FIG. 3 shows an example of such an apparatus.

In FIG. 3, LA is a laser light source, M is a mirror, BS is a beam splitter, and CC is a magnetic head arm ARM1.
A retro-reflector like the corner cube provided above, PD is a photodetector.

In this apparatus, a laser light source LA, a mirror
M, beam splitter BS, and retroreflector CC constitute a Michelson-type interferometer, and the photodetector PD detects the interference light between the light beams L1 and L2 that have passed through the retroreflector CC and the mirror M, respectively. ARM1
Have obtained location information. Then, based on the obtained detection signal, the signal processor SP issues a command, and controls the current flowing from the voice coil motor driver VCMD to the voice coil VOIC to directly move the magnetic head arm and add appropriate control. is there.

However, in such an apparatus, it is necessary to mount a retro-reflector CC such as a corner cube on the magnetic head arm, and the change in the gap between the slider and the hard disk due to securing a space or increasing the weight tends to be a problem.

In view of the above-mentioned conventional example, the present invention does not require the provision of an oversized member on the rotating object when using an interferometer type non-contact distance sensor for the rotating object, and It is another object of the present invention to provide a rotating object position detecting device and a positioning device capable of detecting and positioning the position of a rotating object with high reliability, and an information recording device using the same.

[0017]

According to a first aspect of the present invention, there is provided an interferometer which rotates about the same rotation axis as the rotation of a rotating object, and performs measurement from the interferometer. A position detecting device for detecting position information of a rotating object by causing light reflected by the rotating object of a light beam to interfere with the interferometer.

A second invention for achieving the above object is:
An interferometer that rotates about the same rotation axis as the rotation of the rotating object, and the reflected light of the measurement light beam from the interferometer reflected by the rotating object is caused to interfere by the interferometer. A position detecting device for detecting position information and continuing to detect the position information of the rotating object while controlling the positional relationship between the rotating object and the interferometer to be constant based on the detection. .

A third invention for achieving the above object is
An arm member that rotates about the same rotation axis as the rotation of the rotating object, and at least a measurement light beam emitting unit and a reference light forming unit for the rotating member are arranged on the arm member. An interferometer that obtains relative displacement information with respect to the rotating object by interfering with the reflected light of the measurement light from the moving object, and maintains a relative positional relationship between the rotating object and the interferometer based on the relative displacement information. And a position control system for performing control to make the position detection.

A fourth invention for achieving the above object is:
An interferometer that rotates about the same axis of rotation as the rotation of the rotating object, and interfering the reflected light of the measurement light beam from the interferometer by the rotating object with the interferometer. A positioning device, wherein a relative positional relationship with the rotating object is detected, and the rotating object is made to follow the displacement of the interferometer based on the detection result.

According to a fifth aspect of the present invention for achieving the above object,
An interferometer that rotates about the same rotation axis as the rotation of the rotating object is provided, and the reflected light of the measuring light beam from the interferometer by the rotating object interferes with the interferometer, whereby the position of the rotating object is changed. A position detection system for detecting information, and a position control system for controlling the positional relationship between the rotating object and the interferometer to be constant based on the detection of the position detection system. A positioning device for positioning a rotating object.

According to a sixth aspect of the present invention for achieving the above object,
An arm member that rotates about the same rotation axis as the rotation of the rotating object, and at least a measurement light beam emitting unit and a reference light forming unit for the rotating member disposed on the arm member; An interferometer that obtains relative displacement information with respect to the rotating object by interfering with reflected light of measurement light from a body, and stabilizes a relative positional relationship between the rotating object and the interferometer based on the relative displacement information And a rotation control system that controls the rotation position of the arm member to control the position of the rotation member.

According to a seventh aspect of the present invention for achieving the above object,
An arm member that is arranged to rotate about the same rotation axis as the magnetic head arm inside the hard disk drive, and an emitting unit and a reference light forming unit for emitting at least the measurement light beam to the magnetic head arm on the arm member Is arranged and interferes with the reference light and the reflected light of the measurement light by a predetermined portion of the magnetic head arm, and obtains the relative displacement information with respect to the magnetic head arm, and the interferometer based on the relative displacement information A position control system for controlling the relative positional relationship between the magnetic head arm and the interferometer to be constant, and a rotation control system for controlling the rotation position of the arm member to control the position of the magnetic head arm And a signal system for transmitting a signal for recording information from the magnetic head to the hard disk to the magnetic head.

[0024]

FIG. 4 is a schematic block diagram of a servo track signal writing apparatus according to a first embodiment of the present invention.

In the figure, the same members as those described above are denoted by the same reference numerals. OPS is an optical non-contact distance sensor unit, ARM
Reference numeral 2 denotes an arm for the optical non-contact distance sensor unit OPS. As described later, in this embodiment, the arm of the motor MO is used while performing feedback control in the system of the rotary encoder RE, the signal processor SP, and the motor driver MD.
By rotating ARM2, optical non-contact distance sensor unit OP
The structure is such that S is positioned while sequentially performing minute feed.

At the same time, based on the detection signal obtained from the optical non-contact distance sensor unit OPS, the signal processor SP issues a command, and directly controls the current flowing from the voice coil motor driver VCMD to the voice coil VOIC to thereby control the current. By moving the magnetic head arm and performing feedback control so that the positional relationship with the optical non-contact distance sensor unit OPS, which is sequentially finely fed, is kept constant, the magnetic head is finally positioned while being sequentially finely fed. Configuration.

The hard disk drive device has a magnetic head arm ARM1 having a rotation axis outside the hard disk HD.
The slider SLID attached to the tip is arranged with a gap of several microns (or less) facing the hard disk surface, and moves in an arc shape by the rotation of the magnetic head arm ARM1. The rotation is performed by passing a current through the voice coil VOIC. SG is a signal generator for generating a servo track signal to be written to the hard disk, and the servo track signal is written to the hard disk via the magnetic head of the slider SLID.

An apparatus having such a configuration is constituted by a hard disk H
D, slider SLID, magnetic head arm ARM1, voice coil VOIC, etc.
Circuit wiring is appropriate for the magnetic head of VOIC or slider SLID.

The optical non-contact distance sensor unit OPS is
It is arranged outside the hard disk drive HDD, and is arranged so as to be able to rotate and move on a rotation axis coaxial with the rotation center OARM of the magnetic head arm ARM1. The rotational position of the optical non-contact distance sensor unit OPS is measured by a high-resolution rotary encoder RE attached to the rotation axis of the optical non-contact distance sensor unit OPS.

The optical non-contact distance sensor unit OPS emits a light beam, illuminates the side of the magnetic head arm ARM1 or the side of the slider SLID, and returns reflected light to the optical position sensor unit OPS. It is detected by the light receiving element PD inside the non-contact distance sensor unit. Optical non-contact distance sensor unit OPS is composed of optical non-contact distance sensor unit OPS and magnetic head arm ARM.
It operates according to a configuration described later that can measure the distance to 1 or the slider SLID with a resolution of 0.01 micron or less.

Non-contact fine positioning is performed in the following procedure with these device configurations.

First, under the control of the signal processor SP, the optical non-contact distance sensor unit OPS responds to the displacement amount of the magnetic head for switching the servo track signal writing position using the external motor MO and the rotary encoder RE. Is rotated by a small angle. The motor MO and the rotary encoder RE are connected to a rotating shaft, and execute feedback control using a signal from the encoder to perform high-precision rotational positioning without deviation from a specified angle.

Then, the optical non-contact distance sensor unit
From OPS, magnetic head arm ARM1 or slider SLID
A signal indicating that the distance to has changed is output. Detection of a change in distance by the optical non-contact distance sensor unit OPS will be described later.

The signal processor SP receiving the signal from the optical non-contact distance sensor unit OPS moves the magnetic head arm ARM1 to the voice coil VOIC fixed to the base of the magnetic head arm ARM in a direction to cancel this distance change. As described above, the current is passed from the voice coil motor driver VCMD to rotate the magnetic head arm ARM1. The time when it is determined from the signal of the optical non-contact distance sensor unit OPS that the initial state has been reached is when the mutual distance has returned to the original state. When this determination is made, the signal processor SP stops supplying current to the voice coil VOIC.

When the optical non-contact distance sensor unit OPS is further rotated by the smile angle under the control of the signal processor SP to further switch the servo track signal writing position, the optical non-contact distance sensor unit OPS
Outputs a signal indicating that the distance is changing again. Based on this, the above-described control is performed again.

By repeating these at a high speed, the optical non-contact distance sensor unit OPS can perform high-precision positioning and fine-feeding of the magnetic head arm ARM1 (slider SLID) in non-contact and high-precision positioning in conjunction with micro-feeding. . Note that the actual positioning procedure does not need to be performed in the divided procedure as described above, and the magnetic head arm follows the movement of the optical non-contact distance sensor unit across the space according to the optimal control theory. You can move it.
For example, the same digital processor is used for the two signal processors SP shown in FIG. 4, and the A / D conversion circuit (not shown) in each of the rotary encoder RE and the optical non-contact distance sensor unit OPS performs A / D conversion. Is output to the same digital processor, and both feedback controls are performed in parallel in this digital processor with both conditions adjusted.

Next, an optical non-contact distance sensor unit OPS
Will be described based on FIG.

As shown in FIG. 5, the optical non-contact distance sensor unit OPS includes a coherent light source LGT, a collimator lens
It comprises an LNS, a beam splitter BS, a mirror M, and a photoelectric device PD.

Divergent light from a coherent light source LGT such as a laser diode is converted into a substantially parallel light beam by a collimator lens LNS, and split into transmitted light and reflected light by a prism-like beam splitter BS. One is emitted toward the side of the slider, and the light reflected from the side of the slider SLID returns to the original optical path and returns to the beam splitter BS. The other light beam is reflected by the fixed mirror M inside the optical non-contact distance sensor unit, and returned to the beam splitter BS.

In the beam splitter BS, two light beams are combined to form one interference light beam. When the distance from the side surface of the slider SLID changes, the difference in the light path length between the two light beams separated by the beam splitter in the reciprocal direction changes in brightness every integer multiple of the wavelength of the light source.

That is, when a semiconductor laser having a wavelength of 0.78 μm is used as the light source, if the distance from the side surface of the slider SLID is shifted by 0.39 μm, the brightness changes in a sinusoidal manner by one period. The change in brightness is converted into a sinusoidal electric signal by the photoelectric element PD.
If the light and dark signal detected by the photoelectric element PD in the first positional relationship is set to be in the middle of light and dark, the electric signal level changes most sensitively when the distance to the side of the slider SLID changes, Most suitable as an interference type distance sensor. The sinusoidal electric signal change is obtained by dividing one sinusoidal wave (0.39 μm) into several tens of phases by an electric circuit (not shown) in the optical non-contact distance sensor unit OPS, It is output as a displacement signal, which allows a change in distance to be detected with a resolution of about 0.01 micron. Since such an electric circuit is well known, details are omitted.

As described above, the optical non-contact distance sensor unit having a sufficient resolution and rotatably mounted coaxially with the rotation axis of the magnetic head arm is minutely and precisely positioned, and based on the distance information signal, the magnetic head arm is positioned. By controlling the follow-up rotation of the magnetic head arm so that the mutual distance does not change, an apparatus capable of indirectly contacting the magnetic head arm with fine precision without contact can be obtained. With this configuration, a servo track signal writing device with a high density can be realized by repeatedly recording the servo track signal on the hard disk every time the operation is stopped.

In this apparatus, the optical non-contact distance sensor unit OPS is also coaxially rotated with respect to the rotating magnetic head, so that the positional relationship between the magnetic head and the optical non-contact distance sensor unit OPS becomes constant. Since the positioning is performed by such a control, the principle of measurement is not limited to the use of an interferometer that cannot perform the measurement itself if the direction of reflection of the reflected light from the target changes as an optical non-contact distance sensor unit as in this device. This can prevent such a problem from occurring. That is, the control itself such that the positional relationship between the magnetic head and the optical non-contact distance sensor unit OPS is constant,
It is possible to substantially fix the relative incident direction of the reflected light due to the rotation of the magnetic head and the slider with respect to the optical non-contact distance sensor unit. For this reason, a special member such as a retro-reflector for preventing a change in the reflection direction due to rotation need not be provided on the magnetic head side.

The sine-wave-like electric signal level change is as follows.
If there is a two-phase 90 ° phase difference light / dark signal, one sine wave can be divided into several tens to 100 phases by a well-known electric interpolation circuit, so that a distance change can be detected with a higher resolution of 0.001 μm. it can. A modification of the optical non-contact distance sensor unit OPS for generating a two-phase 90 ° phase difference light / dark signal capable of such detection will be described with reference to FIG.

As shown in FIG. 6, divergent light from a coherent light source LGT such as a laser diode is converted into a substantially parallel light beam by a collimator lens LNS, and split into transmitted P-polarized light and reflected S-polarized light by a polarizing beam splitter PBS. One quarter wave plate
Inject through QWP1 to the side of slider SLID,
Return the reflected light from the side surface of the slider SLID to the original optical path and transmit it again through the quarter-wave plate QWP1 to make a polarizing beam splitter
Return to PBS. The other light beam passes through the quarter-wave plate QWP2, is reflected by the fixed mirror M inside the optical non-contact distance sensor unit, passes again through the quarter-wave plate QWP2, and returns to the polarization beam splitter PBS.

The two luminous fluxes returned to the polarizing beam splitter PBS have reciprocally transmitted through a quarter-wave plate, and thus have polarization planes.
Rotated by 90 °, P-polarized light and S-polarized light are exchanged. That is, the P-polarized light flux that first passed through the polarizing beam splitter is S
Since it is a polarized light beam, it is reflected by a polarizing beam splitter. S that first reflected the polarizing beam splitter
Since the polarized light beam is a P-polarized light beam, it passes through the polarizing beam splitter this time.

The two light beams are superimposed on each other and a quarter-wave plate QW
By passing through P3, it is converted into one linearly polarized light beam. The direction of the plane of polarization of the linearly polarized light is related to the phase difference between the wavefronts of the two original light beams, and the plane of polarization of the linearly polarized light is rotated by 180 ° every time the phase difference is shifted by 2π. Therefore, after being split into two linearly polarized light beams by a non-polarizing beam splitter,
One transmits through the polarizing plate PA in the 45 ° direction, and the other transmits 0 °
By transmitting the light through the polarizing plate PB in the azimuth direction, a two-phase signal interference light beam having a sinusoidal light-dark change timing shifted by 90 ° is generated. And separate photoelectric elements PD-A, PD-B
As a result, a two-phase signal having a 90 ° phase difference is generated.

The obtained two-phase signal is divided into several tens to 100 phases by an electric circuit (not shown) including an interpolation circuit in the optical non-contact distance sensor unit OPS, and finally a high-resolution A digital displacement signal is obtained. Since such an electric circuit is well known, details are omitted.

The signal contrast (S / N) becomes higher as the amount of light of the two light beams is more balanced. As the signal contrast (S / N) is better, the number of divisions by the above-described electrical interpolation can be increased, and the resolution of distance measurement can be improved. Therefore, by appropriately adjusting the direction of the plane of polarization of the linearly polarized light to be incident on the polarization beam splitter according to the reflectance of the slider side surface, it is possible to adjust the light amount balance between the transmitted P-polarized light and the reflected S-polarized light. , And S / N
Is obtained.

In the first embodiment, the Michelson interferometer is configured as the optical non-contact distance sensor unit OPS to measure the distance with high resolution. However, another interferometer may be used. For example, as shown in FIG. 7, a Fizeau interferometer may be used.

As shown in FIG. 7, in this optical non-contact distance sensor unit OPS, instead of the fixed mirror M,
A half mirror HM is disposed in the middle of the optical path to the slider SLID, and reflected light from the half mirror HM is used as reference light.

More specifically, the divergent light from a coherent light source LGT such as a laser diode is converted into a parallel light beam by a collimator lens LNS, transmitted through a beam splitter BS, and then split into transmitted light and reflected light by a half mirror HM. I do.
The transmitted light is emitted toward the side of the slider SLID, and the reflected light from the side of the slider SLID returns to the original optical path and returns to the beam splitter BS. The light beam reflected by the half mirror HM is also returned to the beam splitter BS.

In the beam splitter BS, two light beams are combined to form one interference light beam. When the distance from the side surface of the slider SLID changes, the difference in the light path length between the two light beams separated by the beam splitter in the reciprocal direction changes in brightness every integer multiple of the wavelength of the light source.

That is, when a semiconductor laser having a wavelength of 0.78 μm is used as a light source, if the distance from the side surface of the slider is shifted by 0.39 μm, the brightness changes in a sinusoidal manner by one period. The change in brightness is converted into an electric signal by the photoelectric element. Others are the same as the first embodiment.

Also, with the optical non-contact distance sensor unit OPS using such a Fizeau interferometer, it is possible to form a two-phase 90 ° phase difference light / dark signal as described with reference to FIG. That is, as shown in FIG. 8, a quarter-wave plate QWP1 is arranged as the half mirror HM, and the system for receiving the reflected light from the beam splitter BS may be the system shown in FIG.

To explain this, divergent light from a coherent light source LGT such as a laser diode is converted into a substantially parallel light beam by a collimator lens LNS, and a prism-like beam splitter is used.
The light passes through the BS, and further illuminates the quarter-wave plate QWT1. 1
The front surface of the quarter-wave plate QWT1 reflects about 4% unless an antireflection film is deposited. It is assumed that an antireflection film is deposited on the back surface. 96% of the luminous flux passes through the quarter-wave plate QWT1 and is emitted toward the side of the slider SLID, and the slider SLID
Return the reflected light from the side to the original optical path and again use the 1/4 wavelength plate
Pass through QWT1 and return to beam splitter BS.

Of the two light beams returned to the beam splitter BS, the light beam reciprocally transmitted through the quarter wavelength plate QWT1 has its polarization plane rotated by 90 °. That is, the two light beams have their polarization planes perpendicular to each other.

The two light beams are superimposed on each other and a quarter-wave plate QW
By passing through T3, it is converted into one linearly polarized light beam. The direction of the plane of polarization of the linearly polarized light is related to the phase difference between the wavefronts of the two original light beams, and the plane of polarization of the linearly polarized light is rotated by 180 ° every time the phase difference is shifted by 2π. Therefore, after splitting into two linearly polarized light beams by the non-polarizing beam splitter NBS, one is transmitted through a 45 ° azimuth polarizing plate, and the other is transmitted through a 0 ° azimuth polarizing plate, thereby forming a sinusoidal wave. A two-phase signal interference light beam whose light-dark change timing is shifted by 90 ° is generated. Then, two-phase signals having a phase difference of 90 ° are generated by receiving light with different photoelectric elements. Other aspects are the same as those described with reference to FIG.

[0059]

As described above, according to the first aspect of the present invention, when performing position detection on a rotating object using an interferometer, the position of the rotating object using a highly reliable interferometer can be reduced without using a special member. Detection can be performed.

According to the second aspect of the present invention, when performing position detection on a rotating object using an interferometer, position detection by a highly reliable interferometer can be performed without using a special member for the rotating object. Can be easily implemented.

According to the third aspect of the present invention, when the position of a rotating object is detected by using an interferometer, the position of the rotating object is detected by a highly reliable interferometer with a simple structure. Can be easily realized.

According to the fourth aspect of the invention, when positioning is performed on the rotating object using the interferometer, the positioning can be performed based on the highly reliable interferometer without using a special member for the rotating object. And highly accurate positioning can be easily realized.

According to the fifth aspect of the present invention, when positioning is performed on a rotating object using an interferometer, a highly reliable interferometer is used to detect the position without using a special member for the rotating object. And highly accurate positioning can be easily realized.

According to the sixth aspect of the present invention, when positioning the rotating object using the interferometer, the rotating object side is based on position detection by a highly reliable interferometer with a simple structure. High-precision positioning can be easily realized.

According to the seventh aspect of the present invention, when information is recorded by performing positioning using the interferometer with respect to the magnetic head arm of the hard disk drive, high reliability is obtained without specially modifying the hard disk drive. High-precision positioning based on position detection by an interferometer can be performed, and based on this, higher-density information recording on a hard disk can be stably performed.

[Brief description of the drawings]

FIG. 1 shows a hard disk drive device.

FIG. 2 is an explanatory diagram of a conventional servo track signal writing device using a push rod.

FIG. 3 is an explanatory diagram of a conventional servo track signal writing device using a non-contact interferometer.

FIG. 4 is a schematic configuration diagram showing a servo track signal writing device according to a first embodiment of the present invention;

FIG. 5 is an explanatory diagram of an optical interference distance sensor unit according to the first embodiment of the present invention.

FIG. 6 is an explanatory diagram of a modification of the optical interference distance sensor unit.

FIG. 7 is an explanatory view of a modification of the optical interference distance sensor unit.

FIG. 8 is an explanatory diagram of a modification of the optical interference distance sensor unit.

[Explanation of symbols]

LGT Light source HDD Hard disk drive HD Hard disk SLID Slider ARM1 Magnetic head arm ARM2 Support arm of non-contact optical distance sensor unit VOIC Voice coil OPS Optical non-contact distance sensor unit RE High-precision rotary encoder MO Motor BS Beam splitter HM Half mirror QWP1 , QWP2, QWP3 quarter wave plate

Continuing on the front page (72) Inventor Shujiro Kadowaki 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Jun Junwa 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (7)

[Claims] 1. An interferometer that rotates about the same rotation axis as the rotation of a rotating object, wherein reflected light of the measurement light beam from the interferometer by the rotating object is caused to interfere by the interferometer. A position detecting device for detecting position information of a rotating object by using the method. 2. An interferometer that rotates about the same rotation axis as the rotation of a rotating object, wherein reflected light of a measurement light beam from the interferometer by the rotating object interferes with the interferometer. And detecting the position information of the rotating object while controlling the positional relationship between the rotating object and the interferometer to be constant based on the detection. Position detection device. 3. An arm member that rotates about the same rotation axis as the rotation of the rotating object, and at least a measurement light beam emitting unit and a reference light forming unit for the rotating member are arranged on the arm member. An interferometer that obtains relative displacement information with respect to the rotating object by causing reference light and reflected light of measurement light by the rotating object to interfere with each other, and the interferometer between the rotating object and the interferometer based on the relative displacement information. A position detecting device, comprising: a position control system that performs control for making the relative positional relationship constant. 4. An interferometer that rotates about the same rotation axis as the rotation of the rotating object, wherein reflected light of the measuring beam from the interferometer by the rotating object is caused to interfere with the interferometer. A relative position relationship between the interferometer and the rotating object is detected, and based on the detection result, the rotating object follows the displacement of the interferometer. 5. An interferometer which rotates about the same rotation axis as the rotation of a rotating object is provided, and reflected light of the measuring light beam from the interferometer by the rotating object is caused to interfere by the interferometer. A position detection system for detecting position information of the rotating object,
A position control system for controlling the positional relationship between the rotating object and the interferometer to be constant based on the detection of the position detection system, wherein the rotating object is positioned by controlling the arrangement of the interferometer. Positioning device. 6. An arm member that rotates about the same rotation axis as the rotation of the rotating object, and at least a measurement light beam emitting unit and a reference light forming unit for the rotating member are arranged on the arm member and are referred to. An interferometer that obtains relative displacement information with respect to the rotating object by interfering light and reflected light of measurement light from the rotating object, and a relative position between the rotating object and the interferometer based on the relative displacement information. A position detecting device, comprising: a position control system that performs control to make a positional relationship constant, and a rotation control system that controls a rotation position of the arm member so as to perform position control of the rotation member. 7. An arm member arranged to rotate about the same rotation axis as a magnetic head arm inside a hard disk drive device, and an emitting portion of the measuring beam to at least the magnetic head arm on the arm member. An interferometer in which a reference light forming unit is disposed, and the reference light interferes with reference light and reflected light of measurement light from a predetermined portion of the magnetic head arm to obtain relative displacement information with respect to the magnetic head arm; A position control system for controlling the relative positional relationship between the arm for the magnetic head and the interferometer based on information, and a rotation position of the arm member for controlling the position of the arm for the magnetic head; An information recording apparatus comprising: a rotation control system that performs a rotation; and a signal system that transmits a signal for recording information from a magnetic head to a hard disk to a magnetic head.