JP5417517B2 - Dimple position detection device - Google Patents

Description

  The present invention relates to a device for detecting the position of a dimple of a suspension for a disk device built in, for example, a hard disk device (HDD).

  A hard disk device for writing or reading information on a magnetic disk includes a disk device suspension (hereinafter simply referred to as a suspension) attached to an actuator arm of a carriage, and a magnetic device provided at the tip of the suspension. Has a head. The suspension includes a base plate, a load beam, a flexure, and the like. The flexure is fixed to the load beam. A tongue portion is formed in a part of the flexure. A slider constituting the magnetic head is attached to the tongue portion.

  Dimples are formed by pressing at the tip of the load beam. The dimples project in a bowl shape toward the tongue of the flexure, and the top of the dimple is in contact with the tongue. The back side of the dimple is concave. Since the slider fixed to the tongue swings in the rolling or pitching direction around the top of the dimple, it is important to accurately grasp the dimple position (especially the position of the top of the dimple). is there.

  For example, the following Patent Document 1 discloses an apparatus capable of accurately measuring the positions of parts constituting a suspension. However, in the suspension manufacturing process, when the flexure is fixed to the load beam, the dimple is positioned on the back side of the tongue portion. Therefore, in the detection device described in Patent Document 1, the position of the dimple apex is optically determined. It cannot be detected.

  Even after the flexure is fixed to the load beam, the back side (concave surface) of the dimple can be optically observed without being disturbed by the flexure. Therefore, the present inventors considered to detect the position of the dimple by irradiating illumination light from the back side of the dimple, imaging the light reflected from the back side of the dimple, and performing binarized image processing. . Based on the light spot region obtained by binarization, the position of the vertex of the dimple was obtained.

  However, if the shape of the dimple is distorted or the surface of the dimple is rough and rough, a light spot region (on region) exceeding the binarization level may not be obtained. For this reason, when the reflected light is weak, a light spot region exceeding the binarization level is obtained by performing a dimming operation in which the illumination light is strengthened and the reflected light is strengthened.

JP 2006-308425 A

  However, as a result of diligent research by the present inventors, it has been found that the position of the dimple apex cannot be accurately detected depending on the state of the dimple when the dimming operation as described above is performed. It was. In particular, when the shape of the dimple is distorted, the position (apparent position) of the detected dimple vertex may be greatly deviated from the actual position of the dimple vertex. The reason will be described below.

  The dimples are formed by hitting a part of the load beam using a precise press die and plastically deforming it. For this reason, as the number of times of pressing increases, the mold is worn or deformed, and the molding surface becomes rough. If it does so, the shape of a dimple will be disordered or the surface will become rough.

  The ideal shape of the dimple is a circular rotating body (substantially hemispherical), and the top of the dimple is located at the center of the dimple. In this case, the illumination light irradiated from the back side of the dimple toward the back side of the dimple is reflected on the back side of the dimple apex and is directed straight to the image sensor. For this reason, a peak of reflected light appears at a position corresponding to the center of the dimple, for example, as reflected light distribution A schematically shown in FIG. If this reflected light is weak, the reflected light distribution A may not exceed the binarization level SH1. In that case, the reflected light distribution B exceeding the binarization level SH1 can be obtained by increasing the illumination light and increasing the reflected light.

  The “dimple center” in this specification means the center of the circular contour of the dimple in plan view of the load beam. On the other hand, the “dimple vertex” is a portion of the surface (convex surface) on the convex side of the dimple that protrudes most toward the tongue portion. When the dimple is distorted, the dimple vertex may be displaced from the dimple center.

  When the dimple apex deviates from the dimple center, the reflected light peak appears at a position deviated from the dimple center as shown in, for example, the reflected light distribution A ′ schematically shown in FIG. '. When the reflected light distribution A ′ does not reach the binarization level SH1, the reflected light distribution B ′ exceeding the binarization level SH1 is obtained by increasing the illumination light. However, when the illumination light is strengthened, the peak of the reflected light distribution B ′ further deviates from the center of the dimple as indicated by an arrow D in FIG. 10, and the apparent position of the dimple vertex obtained based on this light spot region is It has been found that the actual position of the dimple apex is shifted by ΔC. For this reason, the position of the vertex cannot be detected accurately depending on the state of the dimple.

  Accordingly, an object of the present invention is to provide a dimple position detection device capable of accurately detecting the position of a dimple vertex.

  The present invention is a device for detecting the position of a dimple formed on a load beam of a suspension for a disk device, wherein the dimple has a back surface that is recessed in a bowl shape, and the device is a suspension for the disk device. The suspension held by the workpiece fixing jig includes a load beam and a flexure provided with a tongue portion fixed to the load beam and in contact with the apex of the dimple. And an illumination device that irradiates illumination light along the axis of the dimple toward the back surface of the dimple of the suspension held by the workpiece fixing jig, and the dimple reflected by the back surface of the dimple An imaging device that captures reflected light having a peak corresponding to the position of the apex of the An image processing unit for processing the image captured in the image, wherein the image processing unit has a means for binarizing the image of the reflected light, and an area of the light spot region obtained by the binarization is predetermined. Means for changing the binarization level to be a value, means for determining the position of a dimple vertex based on the light spot region in a state where the area of the light spot region has reached the predetermined value, and the binarization level Means for performing error processing when the area of the light spot region exceeding the binarization level does not exceed a predetermined value even if the value is reduced to the minimum value.

  According to the present invention, the binarization level is changed according to the intensity of light reflected on the front or back surface of the dimple so as to obtain a light spot region, and when the area of the light spot region reaches a predetermined value In order to determine the position of the dimple vertex based on this light spot area, even if the dimple vertex position is deviated from the center of the dimple, for example, when the shape of the dimple is disordered, the illumination light is strengthened as in the conventional dimming operation. Compared with the case where it does, it can suppress that a light spot area | region shifts | deviates from the position of an actual dimple vertex, and can detect the position of a dimple vertex correctly.

FIG. 3 is a cross-sectional view of a part of a disk device including a suspension. The perspective view of the suspension shown by FIG. 1 is a perspective view of a dimple position detection device according to one embodiment of the present invention. The flowchart which shows an example of the flow of a process of the dimple position detection apparatus shown by FIG. The figure which shows the cross section of a dimple, illumination light, and reflected light typically. The figure which shows typically distribution and the binarization level of reflected light in case the vertex of a dimple exists in a dimple center. The figure which shows typically distribution and the binarization level of reflected light when the vertex of a dimple has shifted | deviated from the dimple center. The figure which shows an example of the light spot area | region of the reflected light binarized. The figure which shows typically distribution of reflected light when illumination light is strengthened when the vertex of a dimple exists in the dimple center. The figure which shows typically distribution of reflected light when illumination light is strengthened when the vertex of a dimple has shifted | deviated from the dimple center.

Hereinafter, an embodiment of the present invention will be described with reference to FIGS.
A hard disk device (HDD) 10 shown in FIG. 1 includes a disk 11 as a recording medium, a plurality of disk device suspensions 13 on which a head unit 12 is mounted, and an arm (actuator arm) 14 for attaching these suspensions 13. Yes. The head unit 12 has a function of magnetically writing and reading information on the recording surface of the disk 11.

  FIG. 2 shows an example of the suspension 13. The suspension 13 includes a base plate portion 15, a load beam 20, a flexure 23 attached to the load beam 20, and the like. The flexure 23 is fixed in a state of being superimposed on the load beam 20 by laser spot welding or the like.

  A tongue 24 that functions as a movable part is provided near the tip of the flexure 23. A slider 25, which is a component of the head unit 12, is attached to the tongue unit 24. When the disk 11 rotates at a high speed, an air bearing is formed by the air flowing between the disk 11 and the slider 25, and the slider 25 slightly floats from the surface of the disk 11. The flying height of the slider 25 is called fly height.

  The load beam 20 has a base portion 31 and a tip portion 32, and dimples 33 are formed in the vicinity of the tip portion 32. The surface of the dimple 33 is a substantially hemispherical convex surface, and protrudes toward the tongue portion 24 of the flexure 23. The apex 33 a of the dimple 33 is in contact with the tongue portion 24. The tongue portion 24 swings together with the slider 25 about the vertex 33a of the dimple 33 as a fulcrum. The back surface side of the dimple 33 is recessed, and a substantially hemispherical concave surface is formed.

  Here, if the apex 33a of the dimple 33 is not positioned at the center in the width direction of the slider 25, the torsional torque of the tongue portion 24 varies, and the fly height of the slider 25 is adversely affected. Further, the dimple 33 is used for evaluating the positional accuracy of the flexure 23 with respect to the load beam 20 when inspecting the suspension 13 after assembly, or used as a position reference when attaching the slider 25 to the tongue portion 24. Or For this reason, it is important to accurately detect the position of the dimple 33.

  FIG. 3 schematically shows an example of the dimple position detection device 50 for detecting the position of the dimple 33. The dimple position detection device 50 includes a table 51 that functions as a base, a lifting platform 52 that can move in the directions indicated by arrows Y and Z, and an imaging device 53 as an example of an imaging device mounted on the lifting platform 52. A camera 54 and a lighting device 55 are provided.

  The illumination device 55 emits illumination light L1 along the axis C1 of the dimple 33 toward the back surface 33b (shown in FIG. 5) of the dimple 33 by an illumination system using ring illumination or a half mirror. Yes.

  The dimple position detection device 50 includes a slide member 56 that can move in the direction of arrow X, a work fixing jig 57 mounted on the slide member 56, an image processing unit 60, a display unit 61, and the like. The image processing unit 60 can use a part of the information processing apparatus 62 having a calculation function such as a personal computer. The image processing unit 60 is electrically connected to the image sensor 53.

  A plurality of suspensions 13 as workpieces to be inspected are held at predetermined positions on the workpiece fixing jig 57 in a state of being arranged at equal intervals in the X direction. These suspensions 13 can detect the dimple positions of each suspension 13 one by one by moving the slide member 56 in the X direction by a servo motor (not shown).

Hereinafter, a procedure for detecting the position of the dimple 33 using the dimple position detection device 50 will be described with reference to FIGS.
In step S <b> 1 shown in FIG. 4, illumination light is emitted from the back side of the dimple 33 toward the vicinity of the dimple 33 of the suspension 13 from the illumination device 55, and the reflected light is imaged by the imaging element 53.

  As shown in FIG. 5, the illumination light L <b> 1 irradiated toward the back surface 33 b of the dimple 33 is reflected by the back surface 33 b of the dimple 33 and enters the image sensor 53 of the camera 54. That is, the image sensor 53 captures the light reflected near the back surface 33 b of the dimple 33. The obtained image data is converted into an electrical signal and sent to the image processing unit 60. In the image processing unit 60, processing described below is performed.

  First, in step S2, the binarization level (threshold value) is maximized. And it transfers to binarization step S3. In the binarization step S3, the reflected light image is binarized by processing based on the binarization level and a predetermined algorithm. That is, a process is performed in which a portion exceeding the binarization level in the captured reflected light image is set as a light spot region (on region) and the other region is set as an off region. Then, the process proceeds to step S4.

  In step S4, the area of the light spot region (on region) obtained by binarization is compared with a predetermined value set in advance. If the area of the light spot region is less than the predetermined value, the process proceeds to step S5. For example, as in the reflected light distribution V1 schematically shown in FIG. 6, if a light spot region exceeding the binarization level H1 is obtained and the area of this light spot region is at a predetermined value, the process proceeds to step S8.

  If it is determined in step S4 that the light spot area is not a predetermined value, the process proceeds to step S5. In step S5, it is determined whether or not the binarization level is minimum. If the binarization level is not the minimum in step S5, the process proceeds to step S6.

  In step S6, processing for lowering the binarization level is performed. For example, when the reflected light does not reach the binarization level H1 as in the reflected light distribution V2 shown in FIG. 6, the binarization level is lowered by one step in step S6, and the process returns to the binarization step S3 again. Thus, by lowering the binarization level until the light spot area reaches a predetermined value, even when the reflected light distribution V2 is relatively weak, for example, when the binarization level is lowered to the position indicated by H2 in FIG. The area of the point area becomes a predetermined value.

  If it is determined in step S5 that the binarization level is the minimum, the binarization level cannot be lowered any further, so that it is determined that the dimple position cannot be detected, and the process proceeds to step S7 for error processing. (For example, an alarm is issued) and the process ends.

  If it is determined in step S4 that the light spot area is a predetermined value, the process proceeds to step S8. In step S8, the position of the vertex 33a of the dimple 33 is calculated based on the light spot region obtained by the above binarization and a predetermined algorithm. For example, the position of the vertex 33a of the dimple 33 is obtained by obtaining the position of the center of gravity of the light spot region. Alternatively, the position of the light peak in the light spot region may be the apex position of the dimple 33. Or you may pinpoint the position of a dimple vertex by processing a light spot area | region by methods other than these.

  As shown in FIG. 5, the dimple 33 has an arcuate rotating body shape (substantially hemispherical bowl shape) centered on the axis C <b> 1, and the position of the vertex 33 a is ideally located at the center of the dimple 33. Yes. In this case, the illumination light L1 irradiated from the direction along the axis C1 is reflected by the back surface 33b of the dimple apex 33a, and the reflected light L2 travels toward the image sensor 53 along the axis C1, so that the dimple 33 is shown in FIG. The peak of the reflected light appears in the center of.

  However, when the shape of the dimple 33 is distorted as indicated by a two-dot chain line Q in FIG. 5 and the position of the vertex 33a is deviated from the center of the dimple 33, the reflected light distribution V3 is schematically shown in FIG. Are not symmetrical, and the peak of light deviates from the center of the dimple 33. In this case, if the illumination light is strengthened so that a region exceeding the binarization level (on region) is obtained, the position of the center of gravity of the light deviates from the vertex 33a of the dimple 33 as described above.

  In the present embodiment, as described above, the binarization level is lowered according to the intensity of the reflected light, and the area of the obtained light spot region becomes a predetermined value, so that the vertex 33a of the dimple 33 is obtained. It is possible to obtain the light spot area necessary for obtaining the position of the dimple without causing a positional shift, and to accurately obtain the position of the dimple vertex based on the light spot area. FIG. 8 shows an example of the light spot region P1 (on region) obtained by binarization and the other off region P2.

  The information processing device 62 determines whether or not the position of the vertex 33a of the dimple 33 detected as described above is within the allowable range, and the dimple position and the determination result are displayed on the display unit 61 in step S9. . When the position of the apex 33a of the dimple 33 is not within the allowable range, the display unit 61 displays, for example, an operator or issues a warning.

  As described above, according to the present embodiment, in order to obtain a light spot region having a predetermined area by changing the binarization level without increasing the illumination light when the reflected light is weak, the illumination light is increased. As a result, there is no problem of shifting the light spot region as seen in some cases, and the position of the dimple vertex can be accurately detected from the back side of the dimple.

  In the present invention, before the flexure is fixed to the load beam, the illumination light is irradiated from the surface side (convex surface side) of the dimple, and the reflected light is imaged, so that the dimple position is taken from the surface side of the dimple. It can also be detected. Needless to say, in implementing the present invention, the components of the dimple position detection device, including the illumination device, the imaging device, and the image processing unit, can be variously changed.

DESCRIPTION OF SYMBOLS 13 ... Suspension 20 ... Load beam 23 ... Flexure 24 ... Tongue part 33 ... Dimple 50 ... Dimple position detection apparatus 54 ... Camera (imaging apparatus)
55 ... Lighting device 60 ... Image processing unit 61 ... Display unit

Claims (1)

An apparatus for detecting the position of a dimple formed on a load beam of a suspension for a disk device, wherein the dimple has a back surface recessed in a bowl shape,
The apparatus has a workpiece fixing jig for holding the disk device suspension, and the suspension held by the workpiece fixing jig is fixed to the load beam and the apex of the dimple. A flexure with a tongue portion that comes into contact with
An illumination device that irradiates illumination light along the axis of the dimple toward the back surface of the dimple of the suspension held by the workpiece fixing jig;
An imaging device that captures reflected light having a peak that is reflected by the back surface of the dimple and corresponds to the position of the apex of the dimple;
An image processing unit that processes an image captured by the imaging device;
The image processing unit
Means for binarizing the image of the reflected light;
Means for changing the binarization level so that the area of the light spot region obtained by the binarization becomes a predetermined value;
Means for determining a position of a dimple vertex based on the light spot region in a state where the area of the light spot region reaches the predetermined value;
Means for error processing when the area of the light spot region exceeding the binarization level does not exceed a predetermined value even if the binarization level is lowered to a minimum value;
A dimple position detection apparatus comprising:

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