JPH05198110A - Head positioning device - Google Patents

Abstract

PURPOSE:To provide new positioning so as to give better operability to a user. CONSTITUTION:The device is provided with a mirror 24 fitted to an arm 32 for turning a head 33 and an auto-collimator 23 which is relatively turnable with a disk main body part to an arm revolving center, and based on detection of the auto-collimator 23, the disk main body part is relatively turned in keeping the relatively positional relation of the auto-collimator 23 and the mirror 24 constant. Thus, the head is controlled to be positioned. By this method, high precision positioning is achieved.

Description

Detailed Description of the Invention

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a head positioning device applicable to a servo track writer for writing servo information on a magnetic disk as a recording medium.

[0002]

2. Description of the Related Art With the recent increase in capacity and size of computers, there is a demand for higher density of magnetic disks used as memories. It is necessary to write a servo information signal on the magnetic disk in advance. The place where the written servo information signal exists is called a servo track on the magnetic disk. As the density of magnetic disks increases, so does the accuracy of manufacturing devices for writing servo tracks.

FIG. 1 is a schematic configuration diagram of a conventional device of this type. In the figure, 1a is a highly accurate frequency stabilized laser light source, 2 is a folding mirror, 3 is a beam splitter,
4 is a head arm of a magnetic disk, 5a and 5b are corner cubes, 6 is a magnetic head, 7 is a magnetic disk, 8 is a light receiver, 9 is a control circuit, 10 is a motor for driving the head arm 4, 11 is a magnetic disk. It is the body case.

Here, the laser light source 1a, the beam splitter 3, the corner cubes 5a and 5b, and the light receiver 8 constitute a laser interferometer, and the amount of movement of the corner cube 5 mounted on the head arm 4 is received. The head arm drive circuit motor 10 is read by the control device 9 and read by the device 8.
Is controlled so as to be a predetermined angle, and the writing position of the magnetic head 6 (position in the radial direction of the magnetic disk 7) is controlled. The magnetic disk 7 is rotated around its center by a dedicated motor (not shown), and the magnetic head 6 forms a plurality of concentric servo tracks.

[0005]

SUMMARY OF THE INVENTION In view of the above-mentioned conventional example, the present invention provides a new head positioning device as a product, which gives a user good operability (for example, high detection accuracy and miniaturization of the device). The first purpose is to do.

According to the present invention, the head can be positioned with high accuracy even in a device in which the arm is rotated in order to move the head relatively in the substantially radial direction of the recording medium as in the conventional example described above. A second object is to provide a head positioning device that can be used.

The present invention is an apparatus for moving a head in the radial direction of a disk-shaped recording medium as in the above-described conventional example to perform recording on the surface of the medium, and to detect the position of the head without increasing the size of the apparatus. A third object of the present invention is to provide a head positioning device capable of achieving the above arrangement.

[0008]

In order to achieve the above-mentioned first and second objects, the present invention is firstly rotatable relative to a recording medium about a first axis and parallel to the first axis. A device for relatively positioning an information recording or reproducing head, which is relatively rotatable also in a direction intersecting the relative rotation direction around a second axis, with respect to the recording medium. The autocollimator for measuring the relative positional relationship with the head substantially along the direction of center rotation, one of the combination of the recording medium and the head, and the autocollimator is mounted and the first collimator is mounted. A rotary table for rotationally driving in a rotary direction about two axes, and the rotary table is rotated corresponding to a positioning position of the head with respect to the recording medium, and based on a measurement result of the autocollimator. It has a relative positional relationship between the autocollimator and the head during rotation of the serial rotary table as having a control unit for relative position control so as kept constant.

In order to achieve the above first and third objects,
The present invention is capable of rotating relative to a recording medium about a first axis and also relatively rotatable about a second axis parallel to the first axis in a direction intersecting the relative rotation direction. A device for positioning the information recording or reproducing head relative to the recording medium, and for measuring the relative positional relationship with the head substantially along the direction of rotation of the second shaft, Alternatively, a photoelectric detection system for photoelectrically detecting a position detection index provided on a member supporting the head from a direction intersecting a plane including a rotation direction about the second axis, and the recording medium and the head And a drive table for mounting and driving one of the photoelectric detection system, the drive table corresponding to the positioning position of the head with respect to the recording medium, and the photoelectric detection system. Measurement result And the manner and a control unit for relative position control of the relative positional relationship between the photoelectric detection system and the head during rotation of the rotary table as kept constant based on.

[0010]

EXAMPLES The present invention will be described below with reference to specific examples.

FIG. 2 shows a first embodiment of the present invention using an autocollimator. 31 is a fixed magnetic disk body, 3
Reference numeral 2 is a swing arm, 33 is a magnetic head for writing and reading, and 34 is a drive mechanism portion of the swing arm. 22
Is a rotary table, and the fixed magnetic disk body 31 is mounted on the table. 23 is an autocollimator,
It is arranged so as to detect the rotational position of the mirror 24 attached to the swing arm 32. The principle of the autocollimator is well known, and detailed description thereof is omitted here. Reference numeral 25 is a detection unit of the autocollimator 23. Reference numeral 27 denotes a control device II, which controls the swing arm drive mechanism 34 in the fixed magnetic disk 31 in accordance with the signal output obtained from the autocollimator detection unit 25 to drive the swing arm 32. Reference numeral 26 is a control device I for positioning the rotary table 22. 28
Is a main controller for controlling the entire servo track writer. The servo track writer is also composed of a device (not shown) necessary for writing a servo track. The fulcrum 35 of the arm 32 and the rotation center of the turntable 22 are substantially coincident with each other.

The procedure for writing a servo track according to this embodiment will be described below.

Generally, the servo tracks of the fixed magnetic disk are written on the surface of the magnetic disk at equal intervals, for example, every 10 μm, and servo information necessary for positioning the head is recorded. In this embodiment, a fixed magnetic disk body for writing servo tracks is installed on the rotary table 22, and the rotary table is rotated by using an encoder or stepping motor so that the heads are positioned so as to have a constant interval.
A plurality of concentric servo tracks are written for each angular positioning position. As shown in FIG. 3, when the distance between the fulcrum 35 of the swing arm 32 and the head 33 is L and the track pitch is P, the positioning angle interval θ of the rotary table is θ = P / L. ..

In this embodiment, the rotation angle of the swing arm is detected by the autocollimator so that the output of the autocollimator is always constant, that is, the head including the mirror 24 is provided for the autocollimator as a non-contact sensor. The drive mechanism section in the fixed magnetic disk is controlled so as not to change the relative positional relationship of the above, and the swing arm is driven. By doing so, the head moves in the radial direction of the magnetic disk surface as the rotary table moves. Therefore, the head is positioned in the disk radial direction by positioning the rotary stage at an angular interval θ = P / L.

By the above operation, the servo track is written while positioning the swing arm at the pitch of the servo track.

In the above embodiment, the fixed magnetic disk is arranged on the rotary table and the autocollimator is arranged on the fixed table. However, the fixed magnetic disk is arranged on the fixed table and the autocollimator is arranged on the rotary table. It is also possible to consider an example in which the rotation angle of the swing arm is detected by an autocollimator. In that case,
The rotation center of the rotary table and the rotation center of the swing arm of the fixed magnetic disk are made to substantially coincide with each other. Further, driving and controlling the drive mechanism portion of the swing arm so that the output of the autocollimator is always constant is the same as in the above example.

The rotary table 22 may be controlled by using a high resolution rotary encoder, an angle detector such as a resolver, or a pulse motor may be used for positioning.

FIG. 2 shows the case where the mirror for detecting the autocollimator is attached to the swing arm itself. In many cases, a fixed magnetic disk uses a voice coil motor to drive the swing arm. It may be provided in the operating part of the voice coil.

The effects of this embodiment will be described below.
For example, in the case of the device as shown in FIG. 1, the relative positional relationship between the corner cube 5 on the arm 4 and the laser interferometer is changed according to the rotation of the arm 4, and the corner cube is effective as the head arm moves. No more light will enter the
There is a drawback that the head cannot be positioned.

In the present embodiment, (the rotary table 22 is originally
The rotation of the arm 32 is controlled so that the inclination of the mirror 24, which should change with the rotation of the arm 24, becomes constant. At this time, the center of rotation of the rotary table 22 and the center of rotation of the arm 32 are substantially aligned. Therefore, even if the arm 32 is positioned at any position in the disk radial direction by the rotation of the rotary table 22, the positional relationship between the autocollimator 23 and the mirror 24 remains substantially unchanged, and the light of the autocollimator is effective. Can be used for measurement. Further, the rotation centers of the rotary table 22 and the arm 32 do not have to be exactly the same. For example, instead of an autocollimator (rather than angle detection)
When a sensor that measures the distance to the mirror 24 is used, if the centers of rotation do not match, the amount of displacement of the entire arm caused by this eccentricity when the rotary table is rotated while performing constant control between the sensor and mirror is the sensor. As a result, it is mixed as an error component in the detection interval value, and accurate positioning becomes difficult. Since the mirror angle detection method is used in this embodiment, the displacement of the entire arm due to this eccentricity is not detected, and therefore accurate positioning can be performed regardless of the presence or absence of some eccentricity.

Next, in the embodiments shown in FIG. 4 and subsequent figures, an index plate having a boundary of reflection and non-reflection is attached to the head arm, and a condensed light flux is irradiated from the outside, and the reflected light obtained from there is spatially separated. The so-called "optical type" that detects a change in distribution with two light receiving elements that are spatially displaced from each other and takes out the variation of the difference output from each other to generate a relative displacement signal between the magnetic head and the non-contact sensor. The origin position detecting means "is used to control the head arm based on the signal so that the relative positional deviation is restored, that is, the relative positional relationship with the non-contact sensor is not changed.

FIG. 4 shows an example in which the magnetic disk device side is placed on a rotary table. In the figure, 100 is the entire magnetic disk device, 101 is a magnetic disk, 102 is a magnetic disk rotation drive actuator (EX. Motor), 103 is a magnetic disk recording head, 104 is a magnetic disk recording head supporting arm, and 105 is an arm. A drive actuator, 106 is an arm drive actuator controller, 200 is a rotary table, 201 is a rotary table drive actuator, 202 is a rotary table position detecting device (EX. Rotary encoder), 203 is a rotary table rotation center, and 204 is a rotary table. An actuator controller, 300 is a magnetic disk recording head position or arm position detection device, 400 is a rotary table position command control signal, and 500 is a magnetic disk recording head position or arm position deviation detection. No., 600 is the position control signal of the arm for a magnetic disk, 700 is a servo track write signal. 107 is a turntable 2
00 and the arm 104 have a common rotation center axis.

The procedure for writing servo information will be described below. An instruction 400 from the CPU sets the position of the turntable to a specific position. (A control system based on a combination of the actuator 201, the position detection device 202, and the actuator controller 204 functions.) When the rotary table rotates, the magnetic disk recording head 103 (or arm 104) and the magnetic disk recording head detection device 300 are connected. And the relative position is displaced, and the displacement signal 500 is input to the CPU (300 is fixed). The actuator 105 is moved by a command 600 from the CPU and is controlled until the displacement signal from the detection device 300 returns to the original value. At the same time, the servo track signal 700 is transmitted to the magnetic disk head to write servo information. Repeat above.

FIG. 5 shows a position detecting device 300 for the magnetic disk recording head 103 or the supporting arm 104.
It is a partial functional explanatory view of. Reference numeral 301 is a light source (parallel light flux), 302 is a wavefront splitting prism, 303 is a cylindrical lens, 305a and 305b are staggered rectangular patterns, 308a and 308b are light receiving elements, 350 is a signal amplification processing board, and 500 is a displacement signal. Note that the wavefront splitting prism 302 and the cylindrical lens 303 are shown only in the y direction in the drawing.

A substantially parallel light beam emitted from the light source 301 is divided into two by a wavefront division prism 302 in two directions (X coordinate direction in the figure), and further, by a cylindrical lens 303, each linear beam shape (in the Y coordinate direction in the figure). (Narrow) and focused on each reflection and non-reflection (rectangular) pattern. The two light fluxes reflected by the reflecting portion of the above pattern pass through the cylindrical lens while returning the beam width to the original value again, and further enter the peripheral portion of the wavefront splitting prism 302 and are refracted, respectively, and the light flux from the light source. The light travels in parallel directions and is incident on each of the light receiving elements 308a and 308b.

Now, in this optical system, when the index 305 moves as shown in FIG. 6, the area of the reflecting portion in the area irradiated with the light flux relatively varies. Therefore, the output difference (analog) signals of the light receiving elements 308a and 308b represent the relative positional deviation between the index and the beam (that is, the position detection device 300), and the resolution is the line width of the linear beam with which the index part is irradiated. Can be decided by. The cylindrical lens 303 is used for the purpose of improving resolution. Further, the direction of deviation of the index can also be determined by whether the output difference signal deviates to + or −.

The above-mentioned difference signal is subjected to signal processing, output as a positional deviation information signal 500 in an arbitrary format and sent to the CPU.

In the embodiment of FIG. 4, the magnetic head position detecting device 300 and the magnetic disk recording device 105 are
It is needless to say that the magnetic disk recording device 105 side may be placed on a rotary table and relatively moved for relative movement, but the magnetic head position detection device 300 side may be placed on a rotary table and rotated.

In the embodiment of FIG. 5, the light beam is divided into two by the wavefront dividing prism, and the two rectangular patterns are independently irradiated and received by the respective light receiving elements, but the example shown in FIG. Can also be considered.

That is, in FIG. 7, a substantially parallel light beam emitted from the light source 301 is condensed into a linear beam by the cylindrical lens 303, and a rectangle (single) composed of reflection and non-reflection portions is formed.
If the beam width d irradiated on the pattern satisfies D <d ≦ 3D with respect to the width D in the moving direction of the rectangular (single) pattern, the light flux reflected by the rectangular single slit Variations in the spatial distribution are detected.

For example, if the index is in the center of the beam irradiation area, the strongest beam travels in the direction of specular reflection, so two light receiving elements 308 arranged symmetrically with respect to the path thereof.
An equal amount of light is incident on a and 308b. Index 30 at this time
If 5 is closer to either side, the balance of the amount of light incident on the light receiving elements 308a and 308b is disturbed.

Further, the order of the cylindrical lens and the wavefront splitting prism may be exchanged, or the cylindrical lens may be omitted.

Further, instead of the wavefront splitting prism, the beam may be irradiated onto the index after the two beams are obtained by amplitude splitting with a half mirror or the like.

In addition, with only one boundary between reflection and non-reflection, which is an index, one linear beam is emitted, and the light beam reflected from it is received by one light receiving element, and its output level Alternatively, a method may be used in which the index displacement signal is generated depending on whether the value is above or below a specific value.

Further, instead of sticking a special index, the shape of a part of the magnetic disk or arm may be substituted, or the index may be printed directly.

It should be noted that, in the above-described embodiments and modifications, for example, even if some of the constituent elements are changed, the order is changed, and additional omissions are made, the "origin position detecting optical device" based on the same principle is sufficient. Needless to say.

By performing head position detection by index detection as in the above-described embodiment, the detection system can be arranged on the upper side of the disk surface with a spatial margin, and the apparatus can be miniaturized.

Next, in FIG. 8, a diffraction grating 305 is attached as an index on the head arm, and a so-called "grating interference type encoder" is used to generate a relative positional deviation signal between the head and the non-contact sensor. An example in which the head arm position is controlled based on the signal so that the relative positional deviation returns to the original position, that is, the relative positional relationship with the non-contact sensor does not change will be described. The same reference numerals as those shown in FIG. 4 indicate the same members. Reference numeral 800 represents a position detecting device, and 805 represents a diffraction grating plate.

FIG. 9 shows a recording head 103 for a magnetic disk.
Alternatively, it is a partial functional explanatory diagram of the position detection device 800 of the supporting arm 104. Reference numeral 800 denotes a body of the position detecting device, 801 denotes a monochromatic light source (EX. Laser diode), 8
02 is a (polarization) beam splitter, 803a, 803b
Is a mirror, 803c is a reflective optical element, 804a, 804
b and 804c are quarter wavelength plates (crystal optical elements), 805
Is a diffraction grating plate mounted on the support arm 104, 8
06 is a (non-polarization) beam splitter, 807a, 807
Reference numeral b is a polarizing plate, 808a and 808b are light receiving elements, 850 is a signal amplification processing board, and 500 is a position shift signal.

Here, an optical description will be given below along the optical path.

The light beam emitted from the monochromatic light source 801 is divided into two by the beam splitter 802 for each polarization component.

The transmitted light (P-polarized light flux) is a quarter wavelength plate 8
After passing through 04a, it enters the diffraction grating plate 805 via the mirror 803a. Since the n-th order diffracted light generated there is emitted in the direction of the reflective optical element 803c, it is returned to the original optical path by the reflective optical element 803c, re-enters the diffraction grating plate 805, and the n-th order diffracted light generated there is reflected by the mirror. 80
Since it is emitted in the direction of 3a, the original optical path is returned as it is,
It retransmits the quarter-wave plate 804a. Quarter wave plate 80
Since it is transmitted back and forth through 4a, the polarization plane is 9
It is rotated by 0 ° and becomes an S-polarized component. Since the S-polarized component is reflected by the beam splitter 802,
The light passes through the quarter-wave plate 804c and becomes a clockwise circularly polarized light beam.

On the other hand, of the light flux from the light source 801, the light flux reflected by the beam splitter 802 (S-polarized light flux)
Passes through the quarter-wave plate 804b and then enters the diffraction grating plate 805 via the mirror 803b. M generated there
Since the next-order diffracted light is emitted in the direction of the reflective optical element 803c,
The diffraction grating plate 8 is returned to the optical path of the reflective optical element 803c.
Since the m-th order diffracted light re-incident on 05 is emitted in the direction of the mirror 803b, it is returned to the original optical path as it is and re-transmitted through the quarter-wave plate 804b. For the same reason, the plane of polarization is rotated by 90 ° and becomes a P-polarized component. Since the P-polarized component is transmitted through the beam splitter 802, it is transmitted through the quarter-wave plate 804c to become a counterclockwise circularly polarized light beam.

It is known that when the light fluxes of and are vector-synthesized, they become a single "linearly polarized light flux".

Further, the nth-order diffracted light is reflected by the diffraction grating plate 805
It is known that the phase of the wavefront shifts by 2π × n due to the relative movement of the pitch, so the phase of the n-th order re-diffracted light is 2
There is a shift of π × n × 2 = 4πn, and the phase of re-diffraction of the m-th order is shifted by 2π × m × 2 = 4πm.

When n = + 1 and m = -1, the phase shift between the two diffracted lights becomes 8π when the diffraction grating relatively moves by one pitch.

The direction of the plane of polarization of the linearly polarized light corresponds to the positional deviation between the two diffracted lights.

[0048]

[Outer 1] Therefore, as the phase difference shifts by π, the polarization plane rotates by 90 °.

Therefore, when the beam splitter 806 divides the light beam into two equal parts and observes the light beam through a polarizing plate 807a which transmits only one polarization component in the 0 ° direction, for example, bright and dark are repeated periodically. .. That is, the phase shift between the two diffracted lights becomes a bright / dark signal of one cycle every 2π and is incident on the light receiving element 808a.

When the other light beam is observed through the polarizing plate 807b which transmits only the polarization component in the 45 ° direction, for example, a bright / dark signal can be similarly obtained.

However, the timing at which the polarization direction of the polarization plate 807b and the polarization plane of the signal light beam coincide with each other, and the polarization plate 807a
And the timing at which the polarization planes of the signal light beams coincide with each other are deviated from each other, and the deviation amount is 1/4 of the light-dark cycle.

Since the two light receiving elements 808a and 808b can obtain sinusoidal periodic signals whose timings are shifted from each other, the direction in which the phases of the two light beams are shifted, that is, the moving direction of the diffraction grating 805 can be known.

The above two signals are subjected to signal processing, output as a positional deviation information signal 500 in an arbitrary format and sent to the CPU.

In the embodiment shown in FIG. 8, the magnetic head position detecting device 800 and the magnetic disk recording device 105 are moved relative to each other in such a manner that the magnetic disk recording device 105 side is placed on a rotary table and moved relatively. However, it goes without saying that the magnetic head position detection device 800 side may be placed on a rotary table and rotated.

In the embodiment shown in FIG. 8, the arrangement of mirrors and prisms in the head position detecting optical system, the method of routing light rays,
The so-called "grating interferometer method" that combines the polarization plane conversion method of the polarized light flux with the wave plate, the method of detecting the phase shift of the diffracted light wavefront due to the position shift of the diffraction grating by interference, and the phase difference periodic signal generation method combined with polarization It is needless to say that the "encoder" is based on the same principle even if a part of the constituent elements is changed, the order is changed, or additional omission is performed.

[0056]

As described above, according to the present invention, it is possible to realize a new head positioning device that gives the user better operability than ever before.

[Brief description of drawings]

FIG. 1 is a diagram of a conventional example.

FIG. 2 is a diagram of an embodiment in which a reflective portion is provided on a head and control is performed so that a relative positional relationship with an autocollimator as a non-contact sensor is not changed.

[FIG. 3] Track pitch P and rotation angle θ of a servo track
It is a figure which shows the relationship of.

FIG. 4 is a view in which an index including reflective and non-reflective parts is provided on the head,
It is a figure of the Example which controls so that a relative positional relationship with a non-contact sensor may not be changed.

5 is a configuration explanatory view of a non-contact sensor and its periphery of the embodiment of FIG.

6A and 6B are explanatory diagrams of variations in the amount of light incident on the light receiving element due to the positional deviation between the non-contact sensor and the index according to the embodiment of FIG.

FIG. 7 is a diagram showing a modification of the non-contact sensor of the embodiment of FIG.

FIG. 8 is a diagram of an embodiment in which a diffraction grating is provided on a head and control is performed so that a relative relationship with a non-contact sensor is not changed.

FIG. 9 is a structural explanatory view of the non-contact sensor and its periphery of the embodiment of FIG.

[Explanation of symbols]

 22 rotary table 23 autocollimator 24 mirror 25 autocollimator detection unit 26 control device I 27 control device II 28 main control device 31 fixed magnetic disk main body 32 swinging arm 33 magnetic head 34 drive mechanism section 100 magnetic disk main body 101 magnetic disk 102 magnetic Disk rotation driving actuator 103 Recording head 104 Recording head supporting arm 105 Arm driving actuator 106 Arm driving actuator controller 200 Rotary table 201 Rotary table driving actuator 202 Rotary table position detecting device 300 Recording head position or arm position detecting device

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tetsuji Nishimura 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Katsumi Momose 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Incorporated (72) Inventor Kotaro Hosaka 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Hiroharu Narumi 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (3)

[Claims] 1. A relative rotation can be made relative to a recording medium about a first axis and a relative rotation can be made in a direction intersecting the relative rotation direction about a second axis parallel to the first axis. An apparatus for positioning a movable information recording or reproducing head relative to the recording medium, and an autocollimator for measuring a relative positional relationship with the head substantially along the direction of rotation of the second axis. A rotary table on which one of the combination of the recording medium and the head and the autocollimator is mounted and which is driven to rotate in a rotation direction about the second axis as a center, and the head. And rotating the rotary table corresponding to the positioning position with respect to the recording medium, and the relative position between the autocollimator and the head during rotation of the rotary table based on the measurement result of the autocollimator. A head positioning device comprising: a control unit for controlling relative positions so as to keep the relationship constant. 2. A relative rotation can be made relative to a recording medium about a first axis and a relative rotation can be made in a direction intersecting the relative rotation direction about a second axis parallel to the first axis. An apparatus for positioning a movable information recording or reproducing head relative to the recording medium, in order to measure the relative positional relationship with the head substantially along the direction of rotation of the second axis,
A photoelectric detection system for photoelectrically detecting a position detection index provided on a member supporting the head from a direction intersecting a surface including a rotation direction about the first axis or the second axis,
A drive table for mounting and driving one of the combination of the recording medium and the head and the photoelectric detection system, and driving the drive table corresponding to the positioning position of the head with respect to the recording medium. And a control unit for performing relative position control based on the measurement result of the photoelectric detection system so as to keep the relative positional relationship between the photoelectric detection system and the head during rotation of the rotary table constant. Head positioning device. 3. The head positioning device according to claim 2, wherein a diffraction grating is provided as the position detecting index, and the photoelectric detection system has a grating interference encoder.