JPH1194513A - Interference device, position detecting device, positioning device, information storing device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable an optical member arranged in the proximity of an object to detect the position of the object and to position the object in a non-contact way with highly reliability by reflecting one of split beams by a reflecting surface outside a light transmitting member, combining the reflected light with the other beam in the light transmitting member, and obtaining an interference beam. SOLUTION: Divergent light form a laser diode LD is converted into a convergent beam BEAM by a collimator lens COL and after transmission through a non-polarizing beam splitter NBS, is divided into every polarization component by the light dividing surface of a probe-shaped polarizing prism PBS. A reflected beam is brought to convergently illuminate one side surface of a head arm ARM1, and the reflected light passes through the original light path and returns to the light dividing surface of the prism PBS. A transmitted beam is brought to convergently illuminate a reflection deposition film at the end face, and the reflected light passes through the original path and returns to the light dividing surface of the prism PBS. When both beams are combined together, their wave fronts are not perfectly matched with each other. In the case that both polarized light is temporarily combined together, concentric interference fringes are obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an interference apparatus, an apparatus, a positioning apparatus, and an information recording apparatus using the same.
The present invention is particularly applicable to a position detecting device for detecting a position change of an object in a non-contact manner, such as an interferometer for an object such as a magnetic head of a hard disk drive, a positioning device, and a hard disk used for a computer using the same. The present invention can be favorably applied to a drive device (hereinafter referred to as an HDD) manufacturing device, among which a device for writing a servo track signal to a hard disk inside the HDD with high accuracy.

[0002]

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, AR
M1 is a magnetic head arm, VCM is a voice coil motor, OHD
Is the HD spindle of the hard disk, and O is the rotation axis of the magnetic head arm ARM1.

[0004] A magnetic recording medium is deposited on the surface of each hard disk. Hard disk HD is spindle OHD
, And a magnetic head is arranged near the surface of each hard disk HD at all times.
The magnetic head is incorporated in a substantially rectangular parallelepiped portion called a slider SLID attached to the end of each arm portion of a magnetic head arm ARM1 having a rotation center O outside the hard disk HD.
By rotating this, it is possible to relatively move in a substantially radial direction on the hard disk HD.

Accordingly, 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.

[0006] The magnetic recording method on the hard disk HD surface firstly uses the rotation center OHD of the hard disk.
Divided into multiple circular tracks with different concentric circle radii,
Further, each annular track is also 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.

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, it is effective to reduce the width of concentrically divided tracks to improve the recording density in the radial direction.

[0008] The recording density in the radial direction is represented by a track density TPI (track / inch) per one inch length.
It is about 000 TPI. This means that the track spacing is about 3 microns. To determine such a fine track pitch, a magnetic head must be mounted on a hard disk.
Resolution of about 1/50 of track width in the radial direction of HD (0.
It is necessary to perform positioning at (05 microns) and write servo track signals in advance. The important technique here is to write servo track signals sequentially while performing high-resolution positioning in a short time.

PROD is a push rod, ARM 2 is an arm for the push rod PROD, MO is a control motor for positioning, RE is a rotary encoder for detecting the rotation amount of the rotating shaft of the motor MO, and SP is a detection output from the rotary encoder RE. A signal processor MD that analyzes and issues a positioning command signal to a magnetic head servo track signal writing position is a motor driver that drives the motor MO according to a command signal of the signal processor SP. These form the rotary positioner RTP.

Conventionally, as shown in FIG. 4, a cylindrical surface of a push rod PROD is pressed against the side of a magnetic head arm ARM1 (an arm portion for a magnetic head for the lower surface of the lowermost hard disk) to form a rotary encoder RE and a signal. While performing feedback control in the system of the processor SP and the motor driver MD, the arm ARM2 is rotated by the motor MO, and the magnetic head arm is finely fed sequentially through the push rod PROD to perform positioning, and the servo track is sequentially transmitted from the signal generator SG. The signal was being written from the magnetic head. At this time, in order to ensure the contact, a slight current was usually passed to the voice coil motor VCM, and the push rod PROD was pressed also from the head arm ARM1 side.

[0011]

Recently, assuming even higher precision positioning, a method of mechanically pressing the magnetic head arm, which may transmit vibration due to rotation of the hard disk to the motor MO, is not employed. A non-contact method for measuring the movement of the magnetic head arm with high precision by optical means has also been devised. FIG. 5 shows an example of such an apparatus.

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 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 beam L1 passed through the retro-reflector CC to the mirror M1 and the mirror M2, respectively.
The light receiving element PD detects interference light between the magnetic head arm L2 and the position information of the magnetic head arm ARM1. Then, based on the obtained detection signal, the signal processor SP issues a command,
By controlling the current flowing from the voice coil motor driver VCMD to the voice coil motor VCM, the magnetic head arm is moved directly and appropriate control is added.

The problem with such an apparatus is that if a relative position measurement is to be performed from a long distance, a large light source must be used, or a retroreflector CC such as a corner cube must be mounted on the magnetic head arm. The problem is that there is a problem that the control characteristics are deteriorated due to the securing of space, the trouble of attaching and detaching, and the increase in weight. On the other hand, when performing relative position measurement using a small light source such as a multi-mode semiconductor laser without providing a special optical member, it is necessary to perform light beam irradiation and reception from a short distance. In this case, the object to be measured may come into contact with the position detecting device in the process of attaching and detaching the hard disk and the position detecting device, and initially setting the magnetic head arm of the hard disk and the position detecting device to the spatially specified position. However, the direct contact of the optical member of the position detecting device has a problem in terms of subsequent measurement accuracy and the like.

The present invention has been made in view of the above-mentioned conventional example, and prevents an optical member of a position detecting device arranged in close proximity to an object from directly contacting, thereby detecting and positioning an object without contact and with high reliability. It is an object of the present invention to provide a position detecting device, a positioning device, an interference device capable of realizing the same, and an information recording device using the same.

[0016]

According to a first aspect of the present invention, a light beam is divided into two light beams in a light transmitting member, and one light beam is divided into two light beams facing the light transmitting member. An interference optical system that reflects the reflected light outside the member, combines the reflected light with the other light beam in the transmission member, and obtains an interference light beam from the combined light beam, supports the light transmission member, and A member having an end protruding toward the reflection surface side from a light transmitting member.

According to a second aspect of the present invention, in order to achieve the above object, information on relative displacement between the reflection surface and the reflection surface is obtained by detecting an interference light beam obtained by the interference device. It is a position detecting device.

According to a third aspect of the present invention, there is provided a positioning apparatus for performing relative positioning with respect to an object having a reflecting surface based on relative displacement information obtained by the above-mentioned position detecting apparatus. It is.

According to a fourth aspect of the present invention, a light beam is divided into two light beams in a light transmitting member, and one light beam is used for a recording / reading head of a hard disk drive facing the light transmitting member. Reflected on the side of the arm means,
An interference optical system for multiplexing the reflected light with the other light beam in the transmission member and obtaining an interference light beam from the combined light beam, and supporting the light transmission member and at the arm means side relative to the light transmission member. A member having a protruding end portion, and sequentially positioning the arm means using a result obtained by detecting the interference light beam to record a servo track signal on a hard disk. It is an information recording device.

According to a fifth aspect of the present invention, a light beam splitting means for splitting a light beam into two light beams is disposed near a reflecting surface which moves relatively, and one of the split light beams is applied to the reflecting surface. And the other split light beam is reflected by the reference reflecting means, and the two light fluxes are returned to the light beam splitting means to overlap and interfere with each other to detect a change in the relative optical path length difference. And the surface from which the light beam is emitted from the light beam splitting device is joined to a portion different from the surface where the light beam is emitted from the light beam splitting device. And a holding means having such a shape.

According to a sixth aspect of the present invention, a relative positioning with respect to an object having the reflecting surface is performed based on a change in a relative optical path length difference obtained by the position detecting device. It is a positioning device characterized by doing.

According to a seventh aspect of the present invention, a light beam splitting means for splitting a light beam into two light beams is disposed near a recording / reading head arm in a hard disk drive. Is reflected by the reflecting surface, the other split light beam is reflected by the reference reflecting means, and the two light fluxes are returned to the light beam splitting means so that the light fluxes overlap and interfere with each other, thereby making a relative optical path length. It is configured to detect a change in the difference, write a servo track signal to the hard disk while sequentially performing the positioning of the arm means using the result of the detection, and a surface from which the light beam is emitted from the light beam dividing means to space. And holding means having a shape such that the light beam splitting means projects toward the arm means side from the optical surface from which the light beam is emitted to the space. A position detecting device according to symptoms.

[0023]

FIG. 1 is a schematic configuration of a servo track signal writing device according to a first embodiment of the present invention.
Hereinafter, the same members as those described above are denoted by the same reference numerals.

The hard disk drive HDD has a magnetic head arm A having a rotation axis O outside the hard disk HD.
RM1 is installed, and the slider SLID attached to the tip of the RM1
It is arranged with a gap of μm (below) 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 motor VCM.

Such a device is spatially arranged at an appropriate position 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, etc., as shown in FIG. I have.

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

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

Here, the position detecting unit NCPU is constituted by an optical sensor unit as described below.

FIG. 2 is an explanatory view of the configuration of an optical system for explaining the optical sensor unit. The optical sensor unit consists of a multimode laser diode LD, a non-polarizing beam splitter NBS, a probe-like polarizing prism PBS, a probe holder PHD, a reference reflecting surface M, a quarter-wave plate QWP, a beam diameter limiting aperture AP, and a beam amplitude splitting. Diffraction grating GBS, polarizing plates PP1 to PP
4. It is composed of photoelectric elements PD1 to PD4 and the like.

The divergent light from the multi-mode laser diode LD is condensed by a collimator lens COL.
M, pass through the non-polarizing beam splitter NBS, and then enter the probe-like polarizing prism PBS composed of a light-transmitting substance of the optical probe NCP, where the light is split by the light-dividing surface of the probe-like polarizing prism PBS for each polarization component. You. The reflected S-polarized light beam is applied to the side of the head arm ARM1 (here, the arm portion for the magnetic head for the lower surface of the lowermost hard disk in this case), which is arranged in a space approximately 300 μm away from the end face of the probe-like polarizing prism PBS. The light is condensed and illuminated near the beam waist, and the reflected light returns to the original optical path as a divergent spherical wave, and returns to the light splitting surface of the probe-like polarizing prism PBS. The P-polarized light flux transmitted by the probe-shaped polarizing prism PBS is condensed and illuminated on the reflective deposition film on the end face at a position shifted from the beam waist (a state before the beam waist),
The reflected light returns to the original optical path, and the probe-shaped polarizing prism PBS
Is returned to the light splitting surface. The wave optical optical path lengths of both optical paths are set so that the optical path length difference between them is within the coherent distance of the light source, that is, they are substantially equal optical path lengths.

Specifically, for example, the shape is given as follows. The width of the probe-shaped polarizing prism PBS made of glass is about 2 mm, and the light beam reflected by the polarizing prism PBS travels 1 mm in the glass, 0.3 mm travels in the air, and reaches the arm arm side ARM1. Illuminated. Therefore, the reciprocating wave optical path length L1 from the polarizing prism to the reflecting surface
= (1 × 1.5 + 0.3) × 2 = 3.6. On the other hand, polarizing prism PB
The luminous flux transmitted by the S travels 1.2 mm through the glass and illuminates the glass end face. Therefore, the round-trip wave optical path length
L2 = (1.2 × 1.5) × 2 = 3.6. Here, the refractive index of the glass was set to 1.5.

Next, the focus position of the light beam (beam waist)
Is set at a position of 0.3 mm emitted from the polarizing prism. Then, the position of the wave source of the divergent spherical wave reflected from the side of the head arm and the reference reflection surface appears to be shifted in the optical axis direction. Assuming that the inside of the probe-shaped polarizing prism is viewed from the light source side, the focal point (wave source) on the side of the head arm is L1 ′ = (1 + 0.3 × 1.5) = 1.45 from the polarizing prism divided surface.
Look at the position. The position of the divergent spherical wave source from the reference reflecting surface is L2 ′ = 1.2 × 2-1.45 = 0.9 from the polarizing prism division surface.
It looks at position 5. However, both positions are visible in the glass. Therefore, both divergent spherical wave sources
0.5mm deviation (imaging optical path length difference occurs)
That is, when the two light beams are superimposed, the wavefronts do not completely coincide with each other, and if the two light beams are polarized, concentric interference fringes are obtained. In such a case, if the phase of the wavefronts of the two fluctuates due to the relative movement of the head arm, concentric interference fringes will appear and flow from the center. However, since the concentric 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 (same phase) interference fringe portion can be obtained widely at the center. 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-type polarizing prism PBS are linearly polarized light beams orthogonal to each other, they do not actually interfere with each other as they are and do not become a bright / dark signal even if detected. When the two light beams reflected by the non-polarizing beam splitter NBS pass through the quarter-wave plate QWP, the linearly polarized light beams that are orthogonal to each other are converted into circularly polarized light beams that are opposite to each other. Is converted into one linearly polarized light that rotates due to the fluctuation of the phase difference.

The rotating linearly polarized light is reflected by the above-described aperture AP.
After that, four beams (in this case, ± 1st-order diffracted light generated in each of the two orthogonal directions) are generated by a phase diffraction grating having a staggered grating structure (that is, a phase diffraction grating having a diffractive action in each of the two orthogonal directions). ). Due to the amplitude division from the same area, any light flux has a shape and intensity unevenness,
Since the properties such as defects are completely divided equally, even if the interference fringes are not one-color or the contrast is lowered for some reason, the influences are all the same. In particular, the reflected light from the side surface of the head arm is disturbed by the minute uneven structure, and the intensity unevenness is strongly generated. The phase diffraction grating is designed to minimize generation of zero-order light at the same time.

The light beams divided into four light beams are arranged in such a manner that their polarization directions are shifted from each other by 45 degrees.
, 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 transmitted to each light receiving element PD1, PD2, PD3, PD4
Is received.

Light receiving element PD1 having a phase difference of 180 degrees from each other
And the signal of PD2 is detected differentially,
The components (this includes the amount of decrease in contrast due to disturbance of the wavefront and the like) are almost removed. This is an A-phase signal. Similarly, the signals of the light receiving elements PD3 and PD4 having a phase difference of 180 degrees are differentially detected, and the DC component is almost removed. This is a B-phase signal. The A and B phase signals have a phase difference of 90 degrees from each other, and the Lissajous waveform observed by the oscilloscope is circular. The amplitude (the size of the circle) of the waveform of the Lissajous fluctuates due to minute irregularities on the side surface of the head arm, but the center position does not fluctuate. Therefore, essentially no error occurs in phase detection (measurement of relative distance). In particular,
The A and B phase signals are converted to a DC component 0 by a binarization circuit (not shown).
Will be binarized with the threshold value as the threshold level, but even if the original A and B phase signals fluctuate in amplitude, the DC component does not fluctuate at 0, so the phase of the binarized signal No fluctuation occurs, so that highly accurate position detection can be performed by the signal processor SP2 using the binarized signal having a stable phase.

Further, by focusing and illuminating the side surface of the head arm, the influence of the variation of the interference state (one color shift) due to the relative angle shift (alignment shift) of the head arm side surface is 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, it is unnecessary to adjust the side of the head arm and the illuminating light beam, and it operates as an interference-type position detection sensor that is very easy to handle.

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 a small change in the unevenness of the head arm according to the illumination position. However, since the center position of the Lissajous waveform does not fluctuate, essentially no error occurs in phase detection.

The positional relationship between the head arm and the position detection sensor is not shifted as long as the head arm and the position detection sensor are rotated about a coaxial rotation axis and the distance between them is kept constant. However, since a perfect coaxial cannot be realized in reality, a relative positional relationship (angular displacement, parallel displacement) occurs during rotation of the two members due to an axis displacement error. However, as described above, essentially no problem occurs even if an alignment shift or a parallel shift occurs.

The signal finally detected is a sinusoidal signal having a cycle of half the wavelength of the light source, since the principle of interference measurement by the reciprocating optical path is used. When using a laser diode with a wavelength of 0.78 μm, the period is 0.39 μm
(Ie, one sine wave every time the distance between the side of the head arm ARM1 and the optical probe NCP changes by 0.39 μm), and the relative distance fluctuation can be detected by counting the number of waves. Further, since two phases (A and B phases) of a sine wave signal having a phase difference of 90 degrees are obtained as described above, the signal is electrically divided by a well-known electric phase dividing device. After counting, the relative positional deviation with finer resolution can be detected. If it is electrically divided into 4096, the relative displacement can be detected to a minimum of 0.095 nm.

The signal processor SP2 supplies a control current to the head arm drive motor (voice coil) VCM via the motor driver VCMD so that the relative displacement thus detected becomes zero. By doing this,
For example, at the above-mentioned wavelength, the relative position of the magnetic head arm ARM1 with respect to the optical probe NCP can be stably maintained (servo applied) at about several times ± 0.095 nm.

On the other hand, a rotary encoder RE for generating a signal of 81000 sine wave / rotation as a specific numerical value is built in,
Optical probe as a position detection sensor attached near the side of the head arm with a radius of 30 mm if using the high-precision rotary positioner RTP that can be divided and positioned in 2048
NCP can be positioned with a resolution several times that of ± 1.4 nm.

Since the relative position stabilization of the position detection 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, by adding a servo for keeping the relative position of the head arm end surface constant to the high-precision rotary positioner via the position detection sensor, the vibration caused by the rotation of the hard disk and the like is applied to the high-precision positioner. Stable positioning accuracy can be obtained without any disturbance such as transmission via the arm ARM1. Signal writing is performed by rotating the arm ARM2 with the motor MO and moving the optical probe NCP while performing feedback control with the system of the rotary encoder RE, signal processor SP, and motor driver MD, and canceling the displacement at this time. By displacing the magnetic head arm ARM1 in the system of SP2, motor driver VCMD, and head arm drive motor VCM, the magnetic head arm is positioned while feeding it minutely sequentially, and the servo track signal from the signal generator SG is sequentially written from the magnetic head. .

The interference between the light beam reflected from the side of the head arm and the light beam reflected from the reference reflecting surface is obtained within the coherent distance of the light source. Single mode laser diodes are
The coherence length is long, but a mode hop occurs, and a phenomenon that the interference phase jumps may occur. In this embodiment, a multi-mode laser is used to make the optical path length substantially equal, and the optical path length equal to or smaller than the coherence distance. Use by difference. As a specific numerical example, assuming that the center wavelength of the light source is λ0 = 780 nm, the full width at half maximum of the multi-mode spectrum envelope is Δλ = 6 nm, and the full width of the coherent distance is generally obtained by dividing the square of λ0 by Δλ, etc. It is about ± 50 μm around the optical path length.

The wavelength of a laser diode generally fluctuates due to fluctuations in the ambient temperature. Center wavelength 780n
Taking a laser diode having an m and a temperature coefficient of 0.06 nm / ° C. as an example, when the optical path length difference ΔL = 50 μm, the deviation of the measured value due to a temperature change of 1 ° C. is about ± 5 nm.

If the distance is kept constant near the coherence peak, an optical path length difference of ± 10 μm can be realized, in which case the measurement error is ± 1 nm. This value is sufficient precision for a servo track writer.

In general, when the laser interferometer is configured such that the optical path is separated and exposed to the air, the signal output is not stable due to fluctuation or the like. However, in the present embodiment, most of the interference optical path is a common optical path, which is separated into two optical paths near the tip of the probe-like polarizing prism but is small and in the glass medium, so that the influence of fluctuation and the like is very small. Is configured.

Here, the probe-shaped polarizing prism PBS is joined to the probe holder PHD and fixed on the rotary positioner arm ARM2 together with the main body of the position detecting device.

The probe holder PHD is inserted into a hollow portion of a cylindrical metal member, and is adhered so as to sandwich the rectangular parallelepiped polarizing prism PBS from both sides with a substantially D-shaped cross-sectional structure. A hole through which the light beam of the pedestal portion of the probe holder PHD passes has a tunnel shape.
The light emitting side end face of the member having a substantially D-shaped cross section of the probe holder PHD is shaped and arranged so as to protrude from the light emitting surface of the polarizing prism PBS by about 100 μm as a specific numerical example.

As described above, the polarizing prism PBS
The distance between the light emitting surface and the side of the head arm ARM1 is 0.3mm
When the range of about ± 0.05 is satisfied, a periodic signal of の of the wavelength of the light source is obtained according to the interval. However, when the position detecting device and the head arm are first arranged in space, the relative position is determined. The relationship is indefinite, and the distance between the polarizing prism PBS beam exit surface and the side surface of the head arm ARM1 must be set by some means so as to satisfy a range of about 0.3 mm ± 0.05. At that time, it is assumed that the two touch each other. However, by employing the probe holder PHD having the holding guide structure as in the present embodiment, it is possible to prevent the probe-shaped polarizing prism PBS itself, which is an optical member, from coming into contact and causing damage and displacement.

Also, since it can be made very small, it can be made to have the same size as the push rod portion (PROD) of the conventional push rod type servo track signal writing device (FIG. 4).

The main effects of the first embodiment will be described below. 1. The position of the head arm side can be measured completely without contact.
In addition, even in the event of contact, the optical member does not contact and is not damaged, so that the resolution, accuracy, stability, and safety of servo writing are improved. Particularly in the case of contact, the two D-shaped ends make contact so that the strength can be maintained. In addition, since the glass polarizing prism PBS is held from both sides via an adhesive, even if stress such as heat or vibration is applied, a force that bends the glass polarizing prism hardly acts, which is safe. 2. Since the principle of laser interferometry is used, the resolution and accuracy are very high. 3. Since the minute uneven surface on the side of the head arm is directly measured, the versatility is high, and it is not necessary to add a special optical element or the like to the hard disk side. 4. Since there is little adverse effect on the measurement system due to misalignment between the side of the head arm and the illuminating light beam, it is easy to adjust the position associated with attachment, detachment, and replacement, and servo writing work to the hard disk can be performed efficiently. 5. Since an equal optical path length interference system is used, the accuracy is relatively high even under temperature fluctuations. 6. Most of the interference light paths are common light paths, and most of the divided light paths are also in the glass, so that there is little reduction in accuracy due to environmental fluctuations.

FIG. 3 shows a probe-shaped polarizing prism holder PHD.
FIG. 7 is an explanatory diagram of a configuration of an optical system according to a second embodiment in which the shape is changed. The other configuration is the same as that of the first embodiment, and the description and drawings are omitted.

In the present embodiment, the D-shaped holding portions are integrated into one, and the contact portion has a cylindrical surface. By adopting this configuration, an optical probe-shaped polarizing prism holder
Even if there is some misalignment between the PHD and the hard disk HD surface, the contact position is constant, and the initial position reproducibility can be improved.

[0056]

As described above, according to the first aspect, when the interference light beam is obtained by using the reflected light from the opposing reflecting surface outside the light transmitting member, the protruding end makes contact between the light transmitting member and the reflecting surface. And the interference light beam can be stably and safely obtained.

According to the second aspect of the present invention, the relative displacement information of the reflecting surface can be obtained with high reliability in a non-contact manner using the stable interference light beam obtained as described above.

According to the third aspect of the present invention, highly reliable and highly accurate positioning can be executed using non-contact and highly reliable relative displacement information.

According to the fourth aspect of the present invention, when an interference light beam is obtained by using reflected light from the facing arm means outside the light transmitting member, contact between the light transmitting member and the arm means is prevented by the protruding end. In addition, the interference light beam can be obtained stably and safely, and the positioning of the arm means can be performed with high reliability and high accuracy by using the interference light beam. As a result, high-density information recording is realized.

According to the fifth aspect of the present invention, when performing the interferometric measurement using the reflected light from the reflecting surface near the light beam dividing means,
Prevent the contact between the light beam splitting means and the reflecting surface by holding means shaped so that the light beam from the light beam splitting means is projected to the reflecting surface side from the optical surface from which the light beam is radiated into space, and obtain a stable and safe interference light beam. Thus, relative displacement information of the reflecting surface can be obtained with high reliability without contact.

According to the sixth aspect of the present invention, highly reliable and highly accurate positioning can be performed using non-contact and highly reliable relative displacement information.

According to the seventh aspect of the present invention, when performing interference measurement using reflected light from the arm means near the light beam splitting means, the arm means is moved closer to the optical surface than the optical surface on which the light beam is emitted from the light beam splitting means into space. The contact between the beam splitting means and the arm means is prevented by the holding means having a shape protruding to the side, and the interference light beam can be obtained stably and safely. Positioning can be executed,
As a result, high-density information recording is realized.

[Brief description of the drawings]

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

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

FIG. 3 is an explanatory diagram of an optical non-contact distance sensor unit and a probe holder of a servo track signal writing device according to a second embodiment.

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 and a retro-reflector interferometer.

[Explanation of symbols]

NCPU Optical non-contact sensor unit NCP Optical probe (Light guide member) NBS Non-polarized beam splitter PBS Polarized prism film M Reflective 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)

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Naoki Kawamata 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor ▲ Makoto Miya ▼ 3-30-2 Shimomaruko, Ota-ku, Tokyo (72) Inventor Shigeki Kato 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Corporation (72) Inventor Hiroyuki Shiomi 3-30-2 Shimomaruko, Ota-ku, Tokyo In company

Claims (7)

[Claims] 1. A light beam is divided into two light beams in a light transmitting member, one light beam is reflected by a reflection surface outside the light transmitting member facing the light transmitting member, and the reflected light beam is reflected by the other light beam. And an interference optical system that combines the light in the transmission member to obtain an interference light beam from the combined light beam, and an end portion that supports the light transmission member and protrudes from the light transmission member toward the reflection surface side. An interference device having a member. 2. A position detecting device, wherein information on a relative displacement between the interference surface and the reflection surface is obtained by detecting an interference light beam obtained by the interference device according to claim 1. 3. A positioning device that executes relative positioning with respect to an object having the reflection surface based on relative displacement information obtained by the position detection device according to claim 2. 4. A light beam is divided into two light beams in a light transmitting member, and one light beam is reflected by a side surface of a recording / reading head arm means of a hard disk drive facing the light transmitting member, and the reflected light is reflected. An interference optical system that multiplexes the other light beam with the transmitting member and obtains an interference light beam from the combined light beam;
A member having an end supporting the light transmitting member and projecting toward the arm means side from the light transmitting member,
An information recording apparatus for sequentially positioning the arm means using a result obtained by detecting the interference light beam and recording a servo track signal on a hard disk; 5. A light beam splitting means for splitting a light beam into two light beams is disposed in the vicinity of a relatively moving reflecting surface, one of the split light beams is reflected by the reflecting surface, and the other split light beam is reflected by the reflecting surface. The light is reflected by the reference reflecting means, the two light fluxes are returned to the light flux dividing means, and the light fluxes are overlapped and interfere with each other. Holding means having a shape which is bonded to a portion different from the surface from which the light beam is radiated to the space and which projects from the light beam splitting means to the reflection surface side from the optical surface from which the light beam is radiated to the space. Position detecting device. 6. A positioning device that performs relative positioning with respect to an object having the reflection surface based on a change in relative optical path length difference obtained by the position detection device according to claim 5. 7. A light beam splitting means for splitting a light beam into two light beams is disposed near a recording / reading head arm means in a hard disk drive, and one of the split light beams is reflected by the reflection surface to be split. The other light beam is reflected by the reference reflecting means, the two light beams are returned to the light beam dividing means, and the light beams are overlapped and interfered with each other to detect a change in the relative optical path length difference. A servo track signal is written to the hard disk while sequentially executing the positioning of the arm means, and is joined to a portion different from the surface on which the light beam is emitted from the light beam splitting means to the space. A position detecting device, comprising: holding means having a shape such that a light beam projects toward the arm means side from an optical surface from which light is emitted into space.