JPH11351822A - Interference apparatus and position detector using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect the position of a body at a high reliability and high accuracy by fixing an electric substrate in a space outside a casing and detecting the position information of the body, utilizing interference signals from sensors. SOLUTION: A position sensor unit mounted on a rotary positioner illuminates a reflector of a magnetic head arm ARM1 with a light beam from near its side face to make the reflected light interfering with a light beam from a reference reflection plane M, thereby stably measuring the distance between the magnetic head arm ARM1 side face and rotary positioner, and a rotary motor is controlled to make the measured value const. A casing PB holding optical components for forming an interference light beam is formed from circular columnar components and held in a hole of a holder PH, an electric substrate EB including photoelectric sensors PD, etc., is fixed to the frame PB and disposed outside the square columnar holder PH and by this constitution, the position information of the body can be detected at a high reliability and high accuracy, without needing special members at the body.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an interference device for detecting a position change of an object, a position detection device for detecting position information of an object such as a magnetic head of a hard disk drive using the same, a positioning device, and a use thereof. Related to a servo signal writing device.

[0002] The present invention is particularly applicable to an apparatus for manufacturing a hard disk drive (hereinafter referred to as an HDD) used in a computer, and particularly to an apparatus for writing a servo track signal to a hard disk in an HDD with high accuracy. It is.

[0003]

2. Description of the Related Art FIG. 4 is an explanatory view of a conventional apparatus for writing a servo track signal to a hard disk in an HDD. In FIG. 4, HDD is a hard disk drive, HD is a hard disk, SLID is a slider, ARM1 is a magnetic head arm, VCM is a voice coil motor, OHD is a hard disk HD spindle (center of rotation), and O is a rotation axis of the magnetic head arm ARM1. It is.

[0004] A magnetic recording medium is deposited on the surface of the hard disk HD. Hard disk HD is spindle OHD
, And a magnetic head is arranged close to the surface of the hard disk HD. The magnetic head is a slider SL attached to the tip of a magnetic head arm ARM1 having a rotation center O outside the hard disk HD.
The magnetic head arm ARM1 is rotationally driven by a voice coil motor VCM and is relatively movable in a substantially radial direction on the hard disk HD.

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

[0006] The magnetic recording system on the hard disk HD surface is based on the rotation center OHD of the hard disk.
Divided into multiple annular tracks with different concentric circle radii,
Further, each of the annular tracks is also divided into several sub-arcs, and is finally recorded and reproduced in a sub-arc region in a time series along the circumferential direction.

Meanwhile, 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 the hard disk, a method of improving the recording density in the radial direction by narrowing the concentrically divided track width is effective.

[0008] The recording density in the radial direction is represented by a track density TPI (track / inch) per one inch length.
It is about 10,000 TPI. This means that the track spacing is about 3 microns. In order to determine such a fine track pitch, it is necessary to position the magnetic head in the radial direction of the hard disk HD at a resolution (0.05 micron) of about 1/50 of the track width and write a servo track signal in advance. . The important technique here is to write servo track signals sequentially while performing high-resolution positioning in a short time.

FIG. 4 shows an outline view of a conventional positioning device for writing a servo track signal. In the figure, PROD is a push rod, ARM2 is a push rod PROD
Arm, MO is positioning control motor, RE is motor MO
The rotary encoder for detecting the amount of rotation of the rotary shaft of SP, SP is a signal processor that analyzes the detection output from the rotary encoder RE and issues a positioning command signal to the write position of the servo track signal of the magnetic head, MD is the signal processor SP It is a motor driver that drives the motor MO by a command signal.

Conventionally, as shown in FIG. 4, a cylindrical surface of a push rod PROD is pressed against a side surface of a magnetic head arm ARM1, and a rotary encoder RE, a signal processor SP,
Push arm by rotating arm ARM2 with motor MO while taking feedback control in the system of motor driver MD
Positioning was performed while sequentially feeding the magnetic head arm ARM1 minutely via PROD, and servo track signals were sequentially written. At this time, in order to ensure contact, usually a slight current is passed to the voice coil motor VCM to
The push rod PROD was also pressed from the M1 side. However, it is necessary to improve the ability to write information such as high-density servo track signals by realizing higher-precision positioning of the rotary positioner system RTP in consideration of vibrations due to rotation of the hard disk HD, etc. .

[0011]

Recently, assuming highly accurate positioning, the movement of the magnetic head arm is measured with high precision by optical means without mechanically pressing the magnetic head arm. Methods have also been devised. FIG. 8 shows an example of an apparatus using optical positioning means.

In FIG. 5, HeNe is a laser light source, M1 and M2.
Is a mirror, BS is a beam splitter, CC is a retroreflector such as a corner cube provided on a part of the magnetic head arm ARM1, and PD is a light receiving element.

In this apparatus, a laser light source HeNe, mirrors M1 and M2, a beam splitter BS, a retro-reflector CC
To form a Michelson interferometer, and the light flux L1, mirror M1, and mirror M2 via the retro-reflector CC and the mirror M2.
The light receiving element PD detects interference light with the light beam L2 passing through the optical head L2 to obtain position information of the magnetic head arm ARM1. 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 motor VCM to directly move the magnetic head arm ARM1 to add appropriate control.

However, in such an apparatus, it is necessary to mount a retro-reflector CC such as a corner cube on the magnetic head arm ARM1, which causes problems such as securing space, labor for mounting and dismounting, and deterioration of control characteristics due to an increase in weight. was there.

According to the present invention, the position information of an object is detected with high reliability and high accuracy and high resolution without the need to provide a special member on the object side, such as a magnetic head arm, and the object is positioned. It is another object of the present invention to provide an interference device, a position detection device, a positioning device, and a servo signal writing device using the same, which can perform measurement in response to fine design changes of various hard disk drives.

[0016]

According to the present invention, there is provided an interference apparatus comprising: (1-1) splitting incident light into two light beams, reflecting one of the split light beams on a reference reflecting surface, and transmitting the other light beam. After being reflected by the reflection surface of the test object, an optical probe that combines and emits the two lights, and a housing provided with an optical member that forms an interference light beam from the light combined by the optical probe, A probe holder for rotatably holding the housing; and an electric board on which a sensor for obtaining an interference signal from an interference light beam from the housing is mounted, and the electric board is fixed to a space outside the housing. And the position information of the test object is detected using an interference signal obtained by the sensor.

(1-2) The light beam is split into two light beams in the light transmitting member, and one of the light beams is reflected by the reflection surface of the test object outside the transmitting member facing the light transmitting member. And an optical probe for reflecting the other light beam on the reference reflection surface and then combining the two light beams in the transmission member, and a housing fixedly provided by the optical probe for obtaining an interference light beam from the combined light beam by the optical probe. A body, a probe holder having a hole with an inner diameter that is in engagement with the outer diameter of the housing, and an electric board on which a sensor that detects an interference light beam from the housing as an interference signal is mounted, and the electric board is It is characterized in that it is spatially arranged in a space outside the housing.

In particular, (1-2-1) the housing has a columnar part, and an optical axis including the light emitting element and the light transmitting member in the housing is the same as the center line of the columnar part. thing.

(1-2-2) The columnar part has a flat portion for fixing the electric board outside the cylindrical surface of the columnar part, and fixes the electric board, or the electric part is fixed to the columnar part. A connecting part for forming a plane for fixing the electric board, the electric board fixed to the connecting part, a relief hole for a light beam guided to enter a sensor fixed to the electric board, the electric board Each of the holder probes is provided with a flat portion for fixing the light source or a relief portion of a connecting component for fixing the electric board, and the relief portion has a light flux even when the columnar component is rotated several tens of degrees in the holder probe. That is enough to make the light incident on the sensor.

(1-2-3) The holder probe has, in the direction of the electric substrate, a concentric circular cylindrical surface portion with a fitting hole for holding the cylindrical component.

(1-2-4) The holder probe has two external planes parallel to the optical axis, and is fixed to a member having a groove portion which is in a fitting relationship with the distance between the two external planes. It is fixed so that it can move in the direction.

The position detecting device of the present invention is characterized in that (2-1) the positioning of the test object is performed by using the interference device having the configuration (1-1) or (1-2).

(2-2) The interferometer of the constitution (1-1) or (1-2) is mounted on a rotary arm of a rotary positioning device having a function of detecting rotation information of a rotary shaft. I have.

The servo signal writing device of the present invention is characterized in that (3-1) the servo track signal is written to the hard disk by using the position detecting device having the constitution (2-1) or (2-2).

(3-2) The light beam is split into two light beams in the light transmitting member, and one of the light beams is reflected by a head arm of a hard disk drive outside the transmitting member facing the light transmitting member, and An optical probe that reflects the other light beam on the reference reflection surface and then multiplexes the two light beams in the transmission member, an interference optical system that obtains an interference light beam from the combined light beam by the optical probe, and the interference optical system. The head arm position detecting device having an electric board mounted with a sensor for detecting the relative displacement with respect to the head arm by receiving the interference light beam from the head arm is attached to the rotating arm of the rotating positioning device, and the position of the rotating positioning device is The current of the head arm drive motor of the hard disk drive is controlled so that the output of the head arm position detector is constant with respect to fluctuations in The arm is configured so that the movement of the arm cooperates, writes a servo track signal on the hard disk every time the rotary positioning device is positioned, and fits the outer diameter of the housing with the housing to which the optical components of the interference optical system are fixed. An electric board having a hole with a related inner diameter in the rotary arm and mounting a sensor for detecting the interference light beam as an interference signal is spatially disposed in a space outside the housing.

In particular, (3-2-1) the housing has a columnar component, and the optical axis including the light emitting element and the light transmitting member in the housing is the same as the center line of the columnar component. .

(3-2-2) The columnar part has a flat portion for fixing the electric board outside the cylindrical surface of the columnar part, and fixes the electric board, or fixes the electric part to the columnar part. A connecting part for forming a plane for fixing the electric board is fixed, the electric board is fixed to the connecting part, and a relief hole of a light beam guided to enter a sensor fixed to the electric board, The rotary arm member is provided with a flat portion for fixing the electric board or a relief portion of a connecting component for fixing the electric board, and the relief portion is such that the columnar component is rotated by several tens of degrees in the rotary arm member. Even if there is enough escape to allow the luminous flux to enter the sensor.

(3-2-3) The rotary arm member has a fan-shaped cylindrical surface portion concentric with the fitting hole for holding the columnar member in the direction of the electric board. And so on.

(3-3) The light beam is split into two light beams in the light transmitting member, and one of the light beams is reflected by the head arm of the hard disk drive outside the transmitting member facing the light transmitting member, and An optical probe that reflects the other light beam on the reference reflection surface and then multiplexes the two light beams in the transmission member, an interference optical system that obtains an interference light beam from the combined light beam by the optical probe, and the interference optical system. The head arm position detecting device having an electric board mounted with a sensor for detecting the relative displacement with respect to the head arm by receiving the interference light beam from the head arm is attached to the rotating arm of the rotating positioning device, and the position of the rotating positioning device is The current of the head arm drive motor of the hard disk drive is controlled so that the output of the head arm position detector is constant with respect to fluctuations in The arm is configured so that the movement of the arm cooperates, writes a servo track signal on the hard disk every time the rotary positioning device is positioned, and fits the outer diameter of the housing with the housing to which the optical components of the interference optical system are fixed. An electric board having a probe holder having a fixing hole having a related inner diameter, the probe holder being fixed to the rotary arm so as to be movable in a radial direction about the rotation axis, and mounting a sensor for detecting the interference light beam as an interference signal; It is characterized in that it is spatially arranged in a space outside the housing.

Particularly, (3-3-1) the optical axis including the light emitting element and the light transmitting member in the housing is the same as the center line of the columnar part.

(3-3-2) The columnar part has a flat portion for fixing the electric board outside the columnar surface of the columnar part and fixes the electric board, or the electric part is fixed to the columnar part. Fixing the connecting parts for constituting the plane to fix the board,
The electric board is fixed to the connecting part, an escape hole for a light beam guided to be incident on a sensor fixed to the electric board, a flat portion for fixing the electric board, or a connecting part for fixing the electric board. Relief portions are provided on the probe holder, respectively, and the relief portions are enough to allow a light beam to enter the sensor even when the columnar part rotates several tens of degrees in the probe holder.

(3-3-3) The housing has a cylindrical component, and the probe holder has a concentric circular cylindrical surface portion and a fitting hole for holding the cylindrical component in the direction of the electric board. To have.

(3-3-4) The probe holder has two external planes parallel to the optical axis, and the rotary arm has a groove portion which is engaged with the distance between the external two planes. Is fixed to the groove of the rotary arm so as to be movable in the groove direction. And so on.

[0034]

FIG. 1 is a schematic diagram of a first embodiment of a servo track signal writing device (servo signal writing device) using an interference device according to the present invention and a position detecting device using the same. In the figure, the same members as those in FIG. 7 are denoted by the same reference numerals.

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, VCM is a voice coil motor, OH
D is the hard disk HD spindle (center of rotation), O
Is a rotation axis of the magnetic head arm ARM1.

A magnetic recording medium is deposited on the surface of the hard disk HD. Hard disk HD is spindle OHD
, And a magnetic head is arranged close to the surface of the hard disk HD. The magnetic head is a slider SLID attached to the tip of a magnetic head arm ARM1 having a rotation center O outside the hard disk HD.
The arm ARM1 is rotationally driven by a voice coil motor VCM so as to be relatively movable in a substantially radial direction on the hard disk HD.

Thus, the rotating hard disk HD
The magnetic head moves circularly so that magnetic information can be written or read at an arbitrary position (track) on the surface of the disk-shaped hard disk.

The hard disk drive HDD is a magnetic head arm having a rotation axis O outside the hard disk HD.
ARM1 is installed, and the slider SLID attached to its tip faces 0.
They are arranged with a gap of 5 μm (below), and move in an arc by the rotation of the magnetic head arm ARM1. The rotation is performed by passing a current through the voice coil motor VCM.

Such a device is spatially disposed at an appropriate position as shown in FIG. 1 with respect to a hard disk drive HDD comprising a hard disk HD, a slider SLID, a magnetic head arm ARM1, a voice coil motor VCM, and the like. I have.

SG is a signal generator for generating a servo track signal to be written to the hard disk. This servo track signal is written to the hard disk HD via the magnetic head of the slider SLID.

The position detection unit NCPU is provided on a support arm (rotating arm, positioner arm) ARM2, and the tip of the optical probe NCP is inserted into an elongated opening (not shown) in the base plate of the hard disk drive HDD. , And are arranged near the side surface of the magnetic head arm ARM1. Support arm ARM2 is magnetic head arm ARM1
It is arranged to be rotatable about a rotation axis coaxial with the rotation center O. The rotation position of the position detection unit NCPU is detected by a high-resolution rotary encoder RE attached to the rotation axis O of the support arm ARM2, and based on the detection data, the signal processor SP1 drives the motor via the motor driver MD. MO is driven to rotate. With this form of feedback control, the position detection sensor unit NCPU is rotationally positioned.

The motor MO, the rotary encoder R
E, motor driver MD, and signal processor S
P1 is a component of the Rotary Positioner (Positioner) RTP.

In this embodiment, the rotary positioner
A means for illuminating the light beam from the position detection sensor unit attached to the RTP toward the reflection part of the side surface ARM1 of the head arm ARM1 from near the side surface of the magnetic head arm ARM1 is spatially held. The relative distance between the arm arm side surface ARM1 and the rotary positioner RTP is stably measured by interfering with the other light beam reflected by the device, and the rotation motor (VCM) of the head arm ARM1 is controlled so that the measured value becomes constant. That is, control driving. It is important that the measurement sensor PD of the same design can measure the position of the optical probe NCP and the laser irradiation angle variably and adjustably with respect to various types of hard disk drives. In particular, an optical axis adjustment mechanism in the radial direction of the axis O of the rotary positioner RTP and in the axial direction of the push pin of the rotary positioner is included.

In this embodiment, the housing PB for holding the optical components forming the interference light beam is formed of a columnar component. The prismatic probe holder PH is held by a holder member (probe holder) PH having a hole in engagement with the cylindrical component, and the electric substrate EB including the photoelectric sensor PD is fixed to the cylindrical component PB. It is characterized by being arranged further outside. Further, the probe holder member PH has two outer surfaces parallel to the optical axis, and is arranged in a square groove provided in the positioner arm ARM2 so as to be movable in the radial direction of the positioner axis.

Here, the position detection unit NCPU is composed of an optical sensor unit (interference device) as described below.

FIGS. 2 and 3 are explanatory diagrams of the configuration of an optical system for explaining an optical sensor unit constituting the position detecting unit (interference device) NCPU of FIG. The optical sensor unit NCPU includes a multimode laser diode LD, a non-polarizing beam splitter NBS, a quarter-wave plate QWP, a light beam diameter limiting aperture AP, a diffraction grating GBS for light beam amplitude division, and a polarizing plate PP1.
~ SP4, sensor probe SPH for photoelectric element PD1 ~ PD4 etc.
And an optical probe (light guide member) NCP. The probe holder holds each element of the sensor probe SPH.

In the sensor probe SPH, the divergent light from the multi-mode laser diode LD is converted into a mild condensed light beam BEAM by a collimator lens COL, and is split into transmitted light and reflected light by a non-polarizing beam splitter NBS.

The light transmitted through the non-polarization boom splitter NBS is split for each polarization component by the probe-type polarizing prism PBS of the optical probe NCP. The reflected S-polarized light beam is placed in a space about 300 μm away from the end face of the probe-like polarizing prism PBS, and irradiates the side of the head arm ARM1 near the beam waist.

Light reflected from head arm ARM1 (signal light)
Returns to the original optical path as a divergent spherical wave, and returns to the probe-like polarizing prism (light splitting surface) PBS. On the other hand, the P-polarized light beam transmitted by the probe-shaped polarizing prism PBS is condensed and illuminated on the reflective deposition film on the end face (reference reflective surface) at a position shifted from the beam waist, and the reflected light (reference light) returns to the original optical path. Is returned to the probe-shaped polarizing prism PBS. The wave optical path lengths of the two light beams are set to be substantially equal to each other within the coherence length of the light source.

For example, the shapes are given as follows. The width of the probe-like polarizing prism PBS in the optical probe NCP made of glass is set to about 2 mm,
The light beam reflected by the PBS travels 1 mm through the glass (NCP), travels about 0.3 mm in the air from the exit surface of the polarizing prism light beam, and illuminates the arm arm side surface ARM1. Therefore, the reciprocating wave optical path length L1 from the polarizing prism PBS to the reflection surface is L1 = (1 × 1.5 + 0.3) × 2 = 3.6.

On the other hand, the light beam transmitted by the polarizing prism PBS travels through the glass by 1.2 mm and is illuminated on the glass end surface (reference reflection surface M). Therefore, the reciprocating wave optical path length L2 = (1.2 × 1.5) × 2 = 3.6. Here, the refractive index of glass (NCP) was set to 1.5.

Next, the light condensing position (beam waist)
Is set at a position of 0.3 mm from the exit surface of the polarizing prism PBS.

Then, the position of the wave source of the divergent spherical wave reflected from the head arm side surface ARM1 and the reference reflection surface M appears to be shifted in the optical axis direction. Looking at the inside of the probe-shaped polarizing prism PBS from the light source side,
Is seen at the position of L1 ′ = (1 + 0.3 × 1.5) = 1.45 from the splitting surface of the polarizing prism PBS. The position of the diverging spherical wave source from the reference reflecting surface is seen at the position of L2 '= 1.2 × 2−1.45 = 0.95 from the division surface of the polarizing prism PBS. However, both positions are visible in the glass.

Therefore, the two divergent spherical wave sources are displaced by 0.5 mm in the glass. When the two light beams are superimposed, the wavefronts do not completely coincide with each other. And concentric interference fringes are obtained. In that case, if the phase of the wavefronts of both fluctuates due to the relative movement of the head arm ARM1, concentric interference fringes appear to spring up and down from the center.

However, since the concentric circular interference fringes have a small shift amount of about 0.5 mm in the optical axis direction between the two divergent spherical waves, a substantially one-color interference fringe portion at the center can be obtained widely. Therefore, an appropriate aperture AP is provided so as to take out only the substantially one-color portion, and a part of the light beam is taken out. Thereafter, it can be treated as a substantially plane wave.

Since the two light beams synthesized by the probe-like polarizing prism PBS are linearly polarized light beams orthogonal to each other, they do not actually interfere with each other to produce a bright / dark signal. When the two light beams are reflected by the non-polarizing beam splitter NBS and pass through the quarter-wave plate QWP, the linearly polarized lights that are orthogonal to each other are converted into circularly polarized lights that are opposite to each other. The light is converted into one linearly polarized light that rotates due to a change in the phase difference between the two.

The rotating linearly polarized light is amplitude-divided into four light beams by a phase diffraction grating GBS having a staggered grating structure. In other words, any light flux is completely equally divided in shape, intensity unevenness, defects, and other properties by amplitude division.
Even if the interference fringes are not one-color or the contrast is lowered for some reason, the effects of the interference fringes are all the same.

Particularly, the reflected light from the head arm ARM1 is
Although the wavefront is disturbed by the minute concavo-convex structure and the intensity unevenness is strongly generated, the wavefronts of the four light beams are disturbed in the same manner and the intensity unevenness is equal.

The luminous fluxes divided into four light beams are arranged in a polarizing plate (analyzer) whose polarization directions are shifted from each other by 45 degrees.
By passing through PP1 to PP4, the light / dark timing is converted into interference light having a phase shifted by 90 degrees. The lowering of the contrast due to the influence of wavefront disturbance and intensity unevenness is all equally affected. Each light and dark luminous flux is supplied to each light receiving element PD1, PD
2, Received by PD3, PD4.

Light receiving element PD having a phase difference of 180 degrees from each other
The signal of 1 and the signal of the light receiving element PD2 are differentially detected, and the DC component (contrast reduction due to wavefront disturbance or the like) is almost removed, and the A-phase signal is obtained.

Similarly, the signals of the light receiving elements PD3 and PD4 having a phase difference of 180 degrees from each other are differentially detected, and the DC component (contrast reduction due to wavefront disturbance, etc.) is almost removed, and the B-phase signal and I do. The A and B phase signals are 90 degrees out of phase with each other, and the Lissajous waveform observed by the oscilloscope is circular. Lissajous waveform amplitude (circle size)
Varies due to minute irregularities on the head arm side surface ARM1, but the center position does not vary. Therefore, essentially no error occurs in phase detection (measurement of relative distance).

Further, by converging and illuminating the head arm side surface ARM1, the interference state changes (one-color deviation) due to the relative angle deviation (alignment deviation) of the head arm side surface ARM1.
The effects of have been avoided. In other words, by condensing illumination, even if there is a misalignment, the main emission direction of the divergent spherical wave is slightly shifted to avoid vignetting of the spherical wave itself, and the overlapping state of the wavefronts of the two divergent spherical waves Does not change, so that the interference state can be stably obtained. Therefore,
There is no need to adjust the side of the magnetic head arm ARM1 and the illumination light beam, and it operates as an extremely easy-to-handle interference type position detection sensor.

Although the illumination position shift (parallel shift) does not contribute to the phase shift of the divergent spherical wave, the interference signal amplitude fluctuates due to the minute unevenness of the leaf spring-like member SP corresponding to the illumination position. .

However, since the center position of the Lissajous waveform does not fluctuate, essentially no error occurs in phase detection.

Head arm ARM1 and position detection sensor NCPU
Are not shifted as long as they are rotated about a coaxial rotation axis and the distance between them is kept constant. However, since there is no perfect coaxial in reality, the relative positional relationship (angular displacement, parallel displacement) occurs between the two members due to an axis displacement error. However, as explained above,
Even if an alignment shift or a parallel shift occurs, essentially no problem occurs.

The signal finally detected is a sinusoidal signal whose cycle is half the wavelength of the light source, since the principle of the measurement is the interference measurement by the reciprocating optical path. When using a laser diode with a wavelength of 0.78 μm, the period is 0.39 μm
Is obtained, and the relative distance fluctuation can be detected by counting the wave number. In addition, since two phases of a sine wave signal having a phase difference of 90 degrees are obtained, a relative position shift with finer resolution can be detected by electrically dividing the signal with a known electric phase dividing device. If it is electrically divided into 4096, the relative displacement can be detected with a minimum of 0.095 nm. If a current is applied to the head arm drive motor (voice coil) by an appropriate control device so that the relative position shift becomes zero, the relative position can be stably maintained at about several times ± 0.095 nm (by applying servos). ) Can be.

If a high-precision rotary positioner RTP that incorporates a rotary encoder RE that generates a signal of 81000 sine wave / rotation and can be divided into 2048 positions is used,
The position detection sensor NCPO mounted near the arm arm side surface ARM1 with a radius of 30 mm can be positioned with a resolution several times ± 1.4 nm.

Since the relative position stabilization of the position detecting sensor itself is about several times of ± 0.095 nm as described above, the positioning resolution combining the two is about the performance of the high-precision rotary positioner itself.

As described above, in this embodiment, a servo for keeping the end face position of the magnetic head arm ARM1 constant via the position detection unit NCPU is added to the high-precision rotary positioner RTP, thereby achieving a high-precision positioner RTP. And stable positioning accuracy without external disturbance.

The above optical components NBS, COL, LD, QWP, AP, GBS
Are fixedly provided at predetermined positions of respective parts of a probe optical base (housing) PB as a columnar component (or a prismatic component). At this time, laser diode LD, optical probe NC
The optical axis including P is located at the center of the column of the columnar part PB. The columnar part PB is further inserted into a prismatic probe holder PH having holes of the same diameter as the columnar part PB and having a fitting relationship. The connection between the columnar component PB and the probe holder PH is performed by a set screw, and after being adjusted to a predetermined rotational phase, the screw is screwed.

The light beam emitted from the laser diode LD and the two light beams reflected by the reference reflection surface M pass through the optical probe NCP as described above, are reflected by the non-polarizing beam splitter NBS, pass through each optical component, and are transmitted to the sensor. PD1 to PD4
In this embodiment, the polarizing plate PP1
PPPP4 and the divided sensors including the sensors PD14PD4 are spatially mounted on the electric board EB outside the columnar part PB and further outside the prismatic probe holder PH, and are connected to the circle by the connecting member. It is fixed to the columnar part PB.

By combining the columnar component PB with the probe holder PH having a fitting hole corresponding thereto, each optical component can be rotated about the optical axis.

Naturally, in consideration of the case where the sensor is rotated around the optical axis including the laser diode LD and the optical probe NCP, the probe holder PH having the fitting hole is provided with the diffraction grating GBS after the emission. And the escape of the connecting component between the columnar component PB and the electric board EB is provided for the adjustment rotation angle.

Further, the positioner arm (rotating arm) ARM2 has a fitting groove PM corresponding to the width L of the prismatic probe holder PH in the radial direction of the positioner axis O, and the probe holder PH is provided with the positioner axis O It can move several tens of millimeters in the radial direction. Probe holder PH
Is fixed to the positioner arm ARM2 with four lead screws from above and from the side.

By providing the above two adjustment functions, it is possible to irradiate the measuring laser beam in the position direction corresponding to the shape of the magnetic head arm ARM1 of each hard disk HD.

In the present embodiment, the position of the optical system of the sensor PD is not affected by the laser diode LD when the rotation of the optical sensor PD is adjusted.

When the rotation of the sensor PD is adjusted, the rotation center of the adjustment is aligned with the optical axis including the laser diode LD and the optical probe NCP. Since the positional relationship between the optical axis and the surface to be measured does not change, it can be independently adjusted as another position adjustment.

Therefore, the adjustment work is easy. In addition, the electric board EB is further placed outside the cylindrical
By arranging the probe holder PH outside the PH, the outer shape of the prismatic probe holder PH can be made to have the same width as the electric board PB.

In other words, the positioner arm ARM2 can be made compact and lightweight, so that
The RTP servo characteristics have been improved, and the positioning has also been improved.

Next, effects obtained in the present embodiment will be described.

(A-1) The optical part is fixed to the cylindrical part PB, and the optical axis including the laser diode LD and NCP (optical probe) is the same as the center line of the cylindrical part. The rotation adjustment and the adjustment of the positioner axis O in the radial direction can be performed independently.

(A-2) Electric board EB on which sensor PD is mounted
Is disposed outside the cylindrical part PB and further outside the probe holder PH, so that the prismatic probe holder
The outer shape of PH can be made the same width as the electric board EB.
That is, the arm ARM2 of the rotary positioner RTD can be configured to be small and lightweight. Therefore, the moment of inertia about the axis of the rotary positioner RTP can be suppressed to a small value, which has the effect of improving the servo characteristics and positioning of the positioner RTP.

(A-3) The irradiation position of the light beam is set to the positioner axis O.
It has a mechanism to adjust the radiation direction of the light and the irradiation angle in the rotation direction around the optical axis, so it can respond to the measurement of various hard disks and respond to the fine design change of various hard disk drives with rapid technological progress Can be measured.

(A-4) Since the minute uneven surface of the side surface ARM1 of the magnetic head arm is directly measured, the versatility is high, and a special optical element or the like does not need to be added to the hard disk HD side (vs. corner cue). Interferometric measurement method for the first time).

(A-5) Since the equal optical path length interference system is used, the accuracy is relatively high even under temperature fluctuations (vs. interferometric length measurement method for corner cueing).

(A-6) Most of the interference optical paths are common optical paths, and most of the optical paths after splitting are also in the glass, so that the accuracy is less likely to decrease due to environmental fluctuations.

In particular, by providing a mechanism for adjusting the rotation of the emitted light around the optical axis and the mechanism for adjusting the movement of the positioner shaft O in the radial direction, the interferometer attached to the rotating arm ARM2 of the positioner RTP provides a variety of hard disk drives with rapid technological progress. The present invention provides an interferometer capable of performing measurement in response to a small design change.

In particular, the effect of the electric board EB being located outside the outer shape of the probe holder PH is great, and a housing (optical base) in which all the optical components are arranged in a small configuration.
It is possible to adjust rotation with all PB included.

That is, when the two adjustments are optimized, that is, it is possible to obtain the maximum interference signal. Further, by performing the rotation adjustment about the optical axis, it is possible to perform the adjustment independently of the linear movement adjustment of the positioner axis O in the radial direction.

In other words, each run-in adjustment is possible,
It also offers ease of adjustment. By placing the electric board EB outside the probe holder PH to achieve such an effect, the proposition of compactness can be achieved. Therefore, the support arm ARM2 of the positioner RTP can be made compact and lightweight, and the moment of inertia around the axis of the positioner RTP can be reduced. This has the effect of improving the servo characteristics and positioning of the positioner.

[0091]

According to the present invention, by setting each element as described above, it is not necessary to provide a special member on the object side, such as a magnetic head arm, and the position information of the object can be reliably obtained. Interfering device, position detecting device, positioning device and its use that can detect the object with high accuracy and high resolution at a degree and can measure the object in response to fine design changes of various hard disk drives The conventional servo signal writing device can be achieved.

In particular, the configuration in which the housing can be held rotatably and the electric board is outside the housing facilitates the rotation adjustment of the probe.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram illustrating a servo track signal writing device according to a first embodiment of the present invention.

FIG. 2 is an explanatory view of an optical non-contact distance sensor unit of the servo track signal writing device shown in FIG. 1 and a detailed view of a probe holder.

FIG. 3 is an explanatory view of an optical non-contact distance sensor unit of the servo track signal writing device shown in FIG. 1 and a detailed view of a probe holder.

FIG. 4 is an explanatory diagram of a conventional servo track signal writing device using a hard disk drive device and a push rod.

FIG. 5 is an explanatory diagram of a conventional servo track signal writing device using a hard disk drive device and a retro-reflector interferometer.

[Explanation of symbols]

 NCPU Optical non-contact sensor unit NCP Optical probe (Light guide member) NBS Non-polarizing beam splitter PBS Polarizing prism film M Reflecting film LGT Light source LD Laser diode COL Collimator lens PD Light receiving element PP Polarizing plate G Transparent substrate QWP Quarter wave plate SLID Magnetic head slider ARM1 Magnetic head arm (rotating member) ARM2 Rotary positioner arm (rotating member) RTP Rotary positioner RE Rotary encoder MO motor MOD Motor driver VCM Magnetic head arm rotating motor (voice coil) VCMD Voice coil motor driver HD Hard disk (recording medium) SPH sensor probe PH probe holder

Claims (18)

[Claims] 1. An incident light is split into two light beams, one of the split lights is reflected by a reference reflecting surface, and the other light is reflected by a reflecting surface of a test object. An optical member that forms an interference light beam from light multiplexed by the optical probe, a probe holder that rotatably holds the housing, and a housing that rotatably holds the housing. An electric board on which a sensor for obtaining an interference signal from an interference light beam from the body is mounted, and the electric board is fixedly arranged in a space outside the housing, and utilizes an interference signal obtained by the sensor. An interference device for detecting position information of the test object. 2. A light beam is split into two light beams in a light transmitting member, and one light beam is reflected by a reflection surface of a test object outside the transmitting member facing the light transmitting member, and the other light beam is reflected by the other light beam. After reflecting the light beam on the reference reflection surface, an optical probe that combines the two in the transmission member, and a housing that fixes an optical component that obtains an interference light beam from the combined light beam by the optical probe, A probe holder having a hole with an inner diameter that fits with the outer diameter of the housing, and an electric board on which a sensor that detects an interference light beam from the housing as an interference signal is mounted, and the electric board is spatially An interference device, wherein the interference device is arranged in a space outside the housing. 3. The housing has a cylindrical component, and an optical axis including the light emitting element and the light transmitting member in the housing is the same as a center line of the cylindrical component. 2. Interference device. 4. The cylindrical part has a flat portion for fixing the electric board outside the cylindrical surface of the cylindrical part, and fixes the electric board, or has a flat surface for fixing the electric board to the cylindrical part. Fixing a connecting part for constituting, fixing the electric board to the connecting part, an escape hole for a light beam guided to enter a sensor fixed to the electric board, a plane part fixing the electric board Alternatively, a relief portion of a connecting component for fixing the electric board is provided in each of the holder probes, and the relief portion allows the light beam to enter the sensor even when the columnar component rotates several tens of degrees in the holder probe. 4. The interference device according to claim 3, wherein the clearance is sufficient. 5. The interference apparatus according to claim 3, wherein said holder probe has a concentric circular sector surface portion in the direction of said electric board with a fitting hole for holding said cylindrical component. 6. The holder probe has two external planes parallel to the optical axis, is fixed to a member having a groove portion which is in a fitting relationship with the distance between the two external planes, and is movable in the groove direction. 3. The interference device according to claim 2, wherein the interference device is fixed. 7. A position detecting apparatus, wherein the position of a test object is determined using the interference apparatus according to claim 1. Description: 8. A position detection device, wherein the interference device according to claim 1 is mounted on a rotation arm of a rotation positioning device having a function of detecting rotation information of a rotation shaft. 9. A servo signal writing device according to claim 7, wherein a servo track signal is written to a hard disk by using the position detection device according to claim 8. 10. A light beam is split into two light beams in a light transmitting member, one light beam is reflected by a head arm of a hard disk drive outside the transmitting member facing the light transmitting member, and the other light beam is reflected. And an interference optical system for obtaining an interference light beam from the combined light beam by the optical probe, and an interference from the interference optical system. A head arm position detecting device having an electric board mounted with a sensor for receiving a light beam and detecting a relative displacement with respect to the head arm is attached to the rotating arm of the rotary positioning device, and the position of the rotary positioning device is changed. On the other hand, the current of the head arm drive motor of the hard disk drive is controlled so that the output of the head arm position detector is constant, and the movement of the rotary positioning device and the head are controlled. The arm is configured so that the movement of the arm cooperates, writes a servo track signal on the hard disk every time the rotary positioning device is positioned, and fits the outer diameter of the housing with the housing to which the optical components of the interference optical system are fixed. A servo having a hole having an inner diameter related to the rotary arm, and an electric board on which a sensor for detecting the interference light beam is detected as an interference signal is mounted spatially outside the housing. Signal writing device. 11. The housing according to claim 10, wherein the housing has a columnar part, and an optical axis including the light emitting element and the light transmitting member in the housing is the same as a center line of the columnar part. Servo signal writing device. 12. The cylindrical part has a flat portion for fixing the electric board outside the cylindrical surface of the cylindrical part, and fixes the electric board, or fixes the electric board to the cylindrical part. A connecting part for forming a plane is fixed, the electric board is fixed to the connecting part, a relief hole for a light beam guided to enter a sensor fixed to the electric board, and the electric board is fixed. A relief part for connecting a flat part or a connecting part for fixing the electric board is provided on each of the rotary arm members, and the relief part detects a light beam even when the columnar part rotates several tens degrees in the rotary arm member. 12. The servo signal writing device according to claim 11, wherein the clearance is sufficient to make the light incident on the servo signal. 13. The servo signal writing device according to claim 11, wherein the rotary arm member has a concentric circular cylindrical surface portion in the direction of the electric board with a fitting hole for holding the columnar member. 14. A light beam is split into two light beams in a light transmitting member, one light beam is reflected by a head arm of a hard disk drive outside the transmitting member facing the light transmitting member, and the other light beam is reflected. And an interference optical system for obtaining an interference light beam from the combined light beam by the optical probe, and an interference from the interference optical system. A head arm position detecting device having an electric board mounted with a sensor for receiving a light beam and detecting a relative displacement with respect to the head arm is attached to the rotating arm of the rotary positioning device, and the position of the rotary positioning device is changed. On the other hand, the current of the head arm drive motor of the hard disk drive is controlled so that the output of the head arm position detector is constant, and the movement of the rotary positioning device and the head are controlled. The arm is configured so that the movement of the arm cooperates, writes a servo track signal on the hard disk every time the rotary positioning device is positioned, and fits the outer diameter of the housing with the housing to which the optical components of the interference optical system are fixed. An electric board having a probe holder having a fixing hole having a related inner diameter, the probe holder being fixed to the rotary arm so as to be movable in a radial direction about the rotation axis, and mounting a sensor for detecting the interference light beam as an interference signal; A servo signal writing device characterized by being disposed in a space outside the housing spatially. 15. The servo signal writing device according to claim 14, wherein an optical axis including the light emitting element in the housing and the light transmitting member is the same as a center line of the cylindrical component. 16. The cylindrical part has a plane portion for fixing the electric board outside the cylindrical surface of the cylindrical part, and fixes the electric board, or a plane for fixing the electric board to the cylindrical part. A connecting part for constituting the above, fixing the electric board to the connecting part, a relief hole for a light beam guided to be incident on a sensor fixed to the electric board, a plane for fixing the electric board The probe holder is provided with an escape portion for connecting a portion or a connecting component for fixing the electric board, and the escape portion allows the light beam to enter the sensor even when the columnar component rotates several tens of degrees in the probe holder. 15. A relief which is sufficient to cause the escape.
Servo signal writing device. 17. The method according to claim 17, wherein the housing has a cylindrical component, and the probe holder has a concentric circular cylindrical surface portion and a fitting cylindrical portion for holding the cylindrical component in the direction of the electric board. The servo signal writing device according to claim 4, wherein 18. The probe holder has two external planes parallel to the optical axis, and the rotary arm has a groove portion which is engaged with the distance between the external two planes, and the probe holder is provided with the probe holder of the rotary arm. 15. The servo signal writing device according to claim 14, wherein the device is fixed to the groove so as to be movable in the groove direction.