JPS63154916A - Method for adjusting position sensor - Google Patents

Abstract

PURPOSE:To eliminate a speed detection error and the phase shift between outputs, by obtaining triangular wave-shaped outputs different in a phase from each other by the relative movement of a scale and a sensor and adjusting the amplitudes of the outputs so as to bring differential values to predetermined values. CONSTITUTION:Triangular wave-shaped outputs SA-SD are obtained by the relative movement of a scale having a predetermined structure and a sensor. The differential wave forms of said outputs are visually observed and adjusted in amplitude using a variable resistor so that the differential values in the vicinity of detection points XA-XD exceeding predetermined voltage upwardly to the right become prescribed values. A first, when each output is matched with output SA1 made obtuse in a wave- form in the vicinity of the max. value and the min. value, the differential wave-form DSA1 thereof becomes a square wave having large amplitude dl. Amplitude d2 is adjusted to the amplitude d1 of an ideal triangular wave and all of the outputs SA-SD are processed in the same manner. By this constitution, even when the output S is distorted, the moving speed error in the vicinity of the detection point X can be removed. When SA supposed to originally possess phase difference of 90 deg. is shifted from SB1, the wavelength of SB1 is raised as a whole to correct the phase difference of detection points XA, XB2 to 90 deg..

Description

[Detailed description of the invention] The present invention will be explained in the following order.

A. Field of industrial application B. Outline of the invention C. Prior art (Figs. 6 to 8) D. Problems to be solved by the invention (Figs. 6 and 8) E. Problems to be solved by the invention Means (Fig. 1 to Fig. 6 and Fig. 8) F action (Fig. 1, Fig. 2, Fig. 4 to Fig. 5 2 and Fig. 8) G embodiment (G1) Formation of the embodiment ( Figures 3 and 6 to 8) (
G2) Speed adjustment method (Figure 1, Figure 3, 4th and 6th
(Fig. 8) (G3) Phase difference adjustment method (Fig. 2, Fig. 3, and Fig. 5 - Fig. 8) (G4) Other embodiments H Effects of the invention A Industrial application field This invention The present invention relates to a method of adjusting a position sensor, and can be applied, for example, to a method of adjusting a position sensor in a hard disk device that detects the position of a head by optical means.

B. Summary of the Invention The present invention provides a method for adjusting a position sensor in which a plurality of triangular wave-shaped detection outputs with different phases are obtained by relative movement of a scale and a sensor, in which the differential value of each detection output is set to a predetermined value. By adjusting, the speed detection error can be adjusted, and by adjusting the voltage level of each detection output separately, the phase shift between each detection output can be adjusted.

C. Prior Art In this type of hard disk drive, a large number of recording tracks formed concentrically on the magnetic disk are recorded by moving a head attached to a head arm in the radial direction of the disk-shaped magnetic disk. Tracking is possible.

As shown in FIG. 6, in such a hard disk device 1, a head 3 attached to one end of a Y-shaped helad arm 4 drives a rotation shaft 5 by a drive device including, for example, a voice coil motor 6. By rotating around the center,
It moves in the radial direction of the magnetic disk 2 and is thus able to track a large number of recording tracks formed concentrically on the magnetic disk 2.

At the other end of the head arm 4, a position sensor 9 of an optical sensor type is provided. The position sensor 9 is composed of a sensor 8 and a scale 7, and includes a light emitting part made of, for example, an LED, a reticle and a photoformer having a structure in which slits with a width of 50 [μm] are deposited at a pitch of 100 [μm] on a transparent glass member, etc. A sensor 8 having light receiving parts such as diodes disposed above and below is attached to the head arm 4 with an integral structure made of a mold or the like. In addition, the scale 7 attached to the chassis and having slits in the same pattern as the reticle deposited on a transparent glass member, for example, is moved by the head arm 4 while sandwiching the gap between the light emitting part and the reticle. The aperture of the overlapping portion of the scale and reticle slits is varied, and thus a detection output in the form of a triangular waveform is obtained from the light receiving section.

In a hard disk device that is designed to perform particularly high-density recording, the track spacing of the magnetic disk is 25 [μm], which is narrower than the slit spacing of the scale 7 and reticle. 50 each
Four reticles 10A, IOB, and 10C1IOD each having slits IIA, 11B, and 10C111D having a width of [μm] and a pitch of 100 [μm] are arranged in 25 (
As shown in FIG.
Four triangular wave-shaped detection outputs SA-S with different phases
s, Sc, So, and thus each detection output SA, S++, Sc, S.

Points where XA, Xll, XC exceed a predetermined voltage in the upward direction to the right
, xo (hereinafter referred to as a detection point), the head 3 is positioned in a just tracking state using the detection output (SA, Ss, Sc, or Sl) corresponding to the target recording track. A position sensor 9 is constructed.

D Problems to be Solved by the Invention However, in the position sensor 9 having such a configuration, for example, if the scale 7 and the sensor 8 are installed in a misaligned state, the detection outputs S, , S, , Sc, SD Waveform distortion may occur, or each detection output SA, Ss, Sc,
There is a problem that the phase of So may shift.

For this reason, in the past, each detection output S1, G
An adjustment method was used in which the maximum and minimum values of the triangular waves of 6, Se, and S were adjusted to predetermined values.
If the degree of rounding of the waveform near the maximum value and minimum value of is different, the adjusted detection outputs SA, Sm, Sc,
The slope of the straight line part of So is different, and each detection output SA, SI
There is a risk that an error may occur in the moving speed of the head arm 4 obtained by l, Sc, and Swa, or that a phase shift may not be resolved, and that tracking may not be achieved in the just tracking state after all.

The present invention has been made in consideration of the above points, and is intended to propose a position sensor adjustment method that can solve the problems of conventional position sensor adjustment methods all at once.

E Means for Solving Problems In order to solve the problems, in the first invention, the detection outputs SA, S6, Sc, SD are triangular waveforms having mutually different phases due to the relative movement of the scale 7 and the sensor 8.
In the position sensor 9, the scale 7 and the sensor 8 are moved at a predetermined speed, and each detection output sA, s, , sc, s is obtained based on the movement result.
The amplitude of each detection output 5ASS3, G6, and SD is adjusted so that each differential value d obtained by differentiating ゎ becomes a predetermined value d2.

Further, in the second invention, in the position sensor 9 configured to obtain triangular wave-shaped detection outputs SA, Ss, Sc, and So having mutually different phases by relative movement of the scale 7 and the sensor 8, the scale 7 and the sensor 8 The position XA,
The voltages of the detection outputs Sa, Ss, Se, and So were adjusted so that m, Xc, and XD had a predetermined phase difference of 90° from each other.

By adjusting the amplitudes of the F-effect detection outputs Sa, Ss, Sc, and So, the slopes of the detection outputs SA, Sll, S6, and SI can be varied, and the differential value can be adjusted based on this. Here, the differential value obtained by differentiating each detection output 5ASS8, G6, SD represents the moving speed of the scale 7 and sensor 8, so by obtaining the differential value according to the predetermined speed, each * Speed detection errors of output outputs Sa, Ss, Sc, and So can be effectively compensated.

Moreover, if the voltage of each detection output SA, Ss, Sc, So is adjusted, each detection output Sa, S++, Sc, So exceeds a predetermined voltage (11ExA, Xs, Xc, XI,
can be adjusted. Here, each detection output SA, S! l, s,
, So is detected based on W Xa , The phase difference between SDs can be effectively adjusted to a predetermined phase difference.

G example An embodiment of the present invention will be described in detail below with reference to the drawings.

(G1) Configuration of the Embodiment In the hard disk drive 1 shown in FIGS. 6 to 8, the four light receiving sections 12A, 12B, 12C, and 12D provided at the bottom of each reticle IOA, IOB, IOC, and 10D. Respective light receiving outputs PA, Pg, Pc, P
a is given to each of the four detection circuits 13A, 13B, 13C113D as shown in FIG.

In the detection circuits 13A, 13B, 13C113D, each light reception output PA, Pm, Pc, Po is connected to a negative feedback resistor vRI.
A, VR11, VR+c, ■First amplifier circuit 14A, 14B, 14C11 having an operational amplifier configuration having RID
It is given to the inverting input terminal of 4D.

Further, the non-inverting input terminals of each amplifier circuit 14A, 14B, 14C214D are connected to a common power supply VA. As a result, each light receiving output PA, P, PClpD is amplified, and each light receiving output Pa is amplified by variable resistors VRIA, VRIIl.
, Pg, Pc, and Pa can be adjusted.

Furthermore, the detection outputs SA, S++, Sc, and So of the amplifier circuits 14A, 14B, 14G, and 14D are resistors R, respectively.
They are connected to the other ends of the variable resistors VR, A, VRtm, VRtc, and VRzo whose one end is grounded via R, R1 and RI5, thereby controlling the voltage adjustment circuits 15A and 15.
B, configure 15C115D, and set variable resistor V Rz i V
R! The respective detection outputs Sa, Ss, and Sc are obtained by changing the resistance values of I, VRzc, and VRzo.

Furthermore, each detection output SA, Ss, Sc, So of the voltage adjustment circuits 15A, 15B, 15C115D is connected to a negative feedback resistor R14% R! Second amplifier circuits 16A, 16B, 16C, 16 having an operational amplifier configuration having l, Rze, and R2°
It is input to the inverting input terminal of D, and its non-inverting input terminal is connected to the common power supply VB. Second amplifier circuit 16A, 16
The output terminals of B, 16G, and 16D are connected to the switch circuit 17, and the detection outputs SA, S6 corresponding to each recording track are output.
, Sc or SI, the position of the recording track can be detected.

(G2) Speed adjustment method In the position sensor 9 configured as described above, for example, due to errors in mounting the sensor 8 and scale 7, each detection output SA,
If waveform distortion occurs in s, Sc, and So, a speed error may occur, but this error is corrected by performing speed adjustment according to the processing procedure shown in FIG.

That is, the adjuster enters the processing procedure in step SPI, and in step SP2, slightly moves the Herad arm 4 while visually observing the output waveform using an oscilloscope, etc., and adjusts the variable resistor V for amplitude adjustment of each detection circuit 13A, 13B, 13C113D. RIA-V RI*, V R
+V Rto and variable resistor R2 for voltage adjustment R2
By adjusting R2 and R1°, each detection output SA,
Adjust the maximum and minimum values of S1.5cSS0 to specified values (for example, 9 [■] and 3 (V)).

In the following step SP3, for example, the head arm 4
The voice coil motor 6 rotates at a predetermined speed.
By applying a control current to the head arm 4, the head arm 4 is moved at a constant speed.

In further subsequent step SP4, the head arm 4
Each detection output SA, Ss, Sc obtained by moving
, So are differentiated using, for example, a differentiating circuit or the like, and while visually observing the resulting differential waveform with an oscilloscope or the like, the detection outputs SA, Sl, Sc,
A variable resistor VR for amplitude adjustment is set so that the differential value near the detection points XA, Xll, Xc, and Xo of S becomes a specified value.
Adjust using VR, VR9, VR+o.

For example, as shown in FIG. 4(B), the first detection output SAI, which has a triangular waveform with rounded waveforms near the maximum and minimum values, changes the maximum and minimum values to a predetermined value, that is, the maximum value in step SP2. Value 9 (V) and minimum value 3 [■
], if it is adjusted to have an amplitude between
As shown in FIG. 4(A), the slope of the straight line portion of the detection output SAI near the detection point ) has a large value compared to

Therefore, the differential waveform DSA of this detection output SAI is the fourth
As shown in Figure (C), the shape of a square wave with a large amplitude is obtained, and the value d1 of the differential waveform near the detection point
By adjusting it to a predetermined value d2 as shown in FIG. 4(E), the slope of the straight line, that is, the moving speed of the head arm 4 obtained thereby, becomes an ideal triangle, as shown in FIG. 4(E). The waveforms S and l can be corrected to have approximately the same value.

Furthermore, in step SP6, each detection output Sa, S
It is determined whether all the differential values of s, Sc, and SD have been adjusted to the specified values, and if a negative result is obtained (in other words, this means that unadjusted detection outputs SA, Sm, Sc, and So remain). ) Returning to step SP5, the amplitude of the detection output SA, S11, SC or So is adjusted again.

Further, if a positive result is obtained in step SP6, the processing procedure is ended in step SP7.

According to the speed adjustment method described above, each detection output SA, Sol
, Sc, and So with reference to the differential waveform so that the values near the detection points XA, Xs, Xc, and Xn become predetermined values. It can be corrected to a value almost equal to the three triangular waveforms,
In this way, even if waveform distortion occurs in the output waveform of each detection output SA, Sll, Sc, SI, the detection points Xa, Xs, Xc
, it is possible to effectively eliminate moving speed detection errors in the vicinity of XEI.

(G3) Phase difference adjustment method In the position sensor 9 having the above configuration, for example, the scale 7
Or, due to errors in the installation of sensor 8, each output output Sa
, Ss, Sc, SD detection points XA, Xs, Xc
, Xo do not have a phase difference of 90° from each other, phase difference adjustment is performed according to the processing procedure shown in FIG.

That is, the adjuster enters the processing procedure from step 5PIO, and in steps 5P11 and 5P12, each detection circuit 13 is adjusted in the same manner as in the case of speed adjustment in FIG.
Variable resistor for amplitude adjustment of A, 33B, 13C113D
VR, VR RI! 1. VR1 VRID and variable resistor for voltage adjustment VR, VRzm, VRzc, V
By adjusting Rto once, each detection output SA, S3
, Sc, and SD are adjusted to specified values, and a predetermined control current is applied to the voice coil motor 6 to move the head arm 4 at a constant speed.

In the following steps 5P13 and 5P14,
Each detection output SA, SL, SC using an oscilloscope etc.
, Sゎ waveform detection points xA, XB, XC, XD are measured, and for example, the first detection output SA and the second detection output S□ which originally had a phase difference of 90° from each other. When the detection points XA and X□ have a phase difference of 120° from each other as shown in FIG.
m is adjusted to raise the waveform of the second detection output S□ as a whole as shown by the dotted line in FIG. 5(B), and SA and Sll! of the first and second detection outputs are adjusted. Adjustment is made so that the phase difference between the respective detection points XA and X becomes 90°.

This corresponds to each detection output SA, Ss,
Detection points XA1X5, Xc in the waveforms of SC and swa
, Xo and the detection outputs SA, Ss,
Even if waveform distortion occurs in Sc and So, the detection outputs SA and Ss
, Sc, So, the straight line part of the upper right part itself is about 80%
By selecting conditions in advance to ensure a certain degree of linearity, it is possible to adjust the phase difference without adversely affecting the speed detection system even if the voltage level is changed.

Subsequently, in step 5P15, each detection output Sa
, Ss, Sc, Sl) detection points XA, ,X3,
It is determined whether or not the phase difference between Xc and XD is 90° with respect to each other. If a negative result is obtained, steps 5P13 and 5P14 are executed again and the detection outputs SA, Ss are obtained in the same manner as in the above case. , Sc, 8 detection points X
The phase difference between A1X1, X6, and Xo is adjusted to be 90°.

Further, if an affirmative result is obtained in step 5P15, the processing procedure is ended in the following step 5P16.

According to the above-described phase difference adjustment method, each detection output SA, , S
3. Detection points of So, SI, XalXs, Xc, Xl1
By paying attention to l and adjusting the voltages of the detection outputs SA, Ss, SC, and So, the phase difference between the detection results can be set to 90'', and thus the phase shift can be corrected well.

(G4) Other embodiments (11 In the above embodiments, an oscilloscope was used to adjust the maximum value and minimum value of each detection output and to adjust the differential value. A similar effect can be obtained using a measuring device.

(2) In the above-described embodiment, the first and second aspects of the present invention are used in the adjustment method of a position sensor having four-phase detection output, but instead of this, other plurality of detection outputs such as six-phase, eight-phase, etc. The present invention can also be applied to a method of adjusting a position sensor designed to obtain an output.

In particular, the speed adjustment method according to the first aspect of the invention can also be applied to a method for adjusting speed errors of a position sensor that uses only a single-phase detection output.

(3) In the above embodiment, a predetermined control current is applied to the voice coil motor to move the head arm at a constant speed, but instead of this, for example, an external mechanical operation can be used to move the head arm at a constant speed. A similar effect can be obtained by moving at speed.

(4) In the above embodiment, the adjustment methods according to the first and second inventions were applied to the position sensor that outputs each detection output having an amplitude of ±3 [V] with 6 [■] as the center. The first and second inventions are not limited to this, but the point is that the point where the upward-sloping part or the downward-sloping part of the triangular wave-shaped detection output exceeds a predetermined voltage is set as a detection point, and the position is detected using this, and furthermore, This is suitable for application to a position sensor that detects speed using differential values in the vicinity.

(5) In the above-described embodiment, an embodiment was described in which the first and second inventions were applied to a method for adjusting a position sensor of a hard disk drive, but the invention is not limited to this, and for example, a machine tool using a motor, etc. This method can be widely applied to other position sensor adjustment methods.

Effects of the Invention As described above, according to the present invention, in a position sensor configured to obtain detection outputs in the form of a plurality of triangular waveforms having mutually different phases by relative movement of the scale and the sensor,
The scale and sensor are moved at a relatively constant speed, the resulting detection output is differentiated, and this differential value is set to a predetermined value by adjusting the amplitude of the detection output, and the slope of each detection output at the detection point is calculated. It is possible to obtain an adjustment method that can be adjusted to a constant value and thus can effectively correct speed errors.

In addition, by moving the scale and sensor relatively at a constant speed and adjusting the voltage of each detection output obtained thereby, it is possible to adjust the phase difference between each detection point of each detection output, thus reducing the phase shift. An adjustment method capable of effective correction can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a flowchart showing an embodiment of the speed adjustment method of the first invention, FIG. 2 is a flowchart showing an embodiment of the phase difference adjustment method of the second invention, and FIG. 3 is a detection circuit of a position sensor. FIG. 4 is a signal waveform diagram for explaining the speed adjustment method of the first invention, FIG. 5 is a signal waveform diagram for explaining the phase difference adjustment method of the second invention, and FIG. FIG. 7 is a route plan view of a hard disk drive using the position sensor adjustment method according to the present invention; FIG. 7 is a route diagram for explaining the relationship between the scale and reticle of the position sensor;
The figure is a signal waveform diagram showing the detection output. DESCRIPTION OF SYMBOLS 1... Hard disk device, 2... Disk, 3... Head, 4... Head arm, 5... Rotating shaft, 6... ...Voice coil motor, 7...Scale, 8...
・Sensor, 9...Position sensor.

Claims (2)

[Claims] (1) In a position sensor configured to obtain triangular wave-shaped detection outputs with mutually different phases by relative movement of a scale and sensor, the scale and sensor are moved at a predetermined speed, and the detection output is obtained based on the movement result. A method for adjusting a position sensor, characterized in that the amplitude of each detection output is adjusted so that each differential value obtained by differentiating each detection output becomes a predetermined value. (2) In a position sensor configured to obtain triangular wave-shaped detection outputs with mutually different phases by relative movement of a scale and sensor, the scale and sensor are moved at a predetermined speed, and the detection output is obtained based on the movement result. A method for adjusting a position sensor, characterized in that the voltages of the detection outputs are adjusted so that the positions where each detection output exceeds a predetermined voltage when rising or falling have a predetermined phase difference from each other.