JPH04178921A - Clamping mechanism of magnetic disk - Google Patents

Abstract

PURPOSE:To enable a small distortion which is generated at a magnetic disk to be reduced by reducing press force of a mechanical clamp mechanism by adopting air suction force. CONSTITUTION:While rotation is at halt and rotary speed is small, a magnetic disk 1 is clamped by a mechanical clamp mechanism 3. On the other hand, when a rotary axis 2c rotates, air is discharged from a jet hole 6a outward for generating a negative pressure inside and this negative pressure generates an air suction force which does not generate a small distortion at a suction groove 2e of a turntable 2a through a through hole 6b. Namely, air suction is adopted for the mechanical clamp. When the rotary speed is increased and air suction force is increased, press force of the mechanical clamp mechanism 3 is reduced by a press force adjusting mechanism 7 inverse-proportionally and both maintain nearly constant clamp force, thus enabling a small distortion which is generated at the magnetic disk 1 to be reduced.

Description

[Detailed description of the invention] [Industry, second field of use] The present invention relates to a magnetic disk clamping mechanism.

[Prior Art] A hard magnetic disk used as a recording medium of an information processing device is inspected for protrusions existing on the surface during the manufacturing stage, and after inspection of the protrusions is completed, test data or servo signals are written/read out. Various inspections such as error tests are performed. During inspection, a magnetic disk is mounted on a spindle (or turntable) and clamped, rotated by a spindle motor, and inspected by a magnetic head (hereinafter referred to as an inspection head).

FIGS. 2(a) to 2(c) show an outline of a magnetic disk inspection apparatus, an example of a mechanical clamp mechanism, and a pressing surface of a magnetic disk. In Figure (a), the rotation mechanism 2 includes a turntable 2a, a spindle motor 2b, and a rotation shaft 2C that couples these together. Further, in the mechanical clamp mechanism 3, the plurality of chuck pieces 3a are connected to the support plate 3b.
The support plate 3b is movably supported by the lifting and lowering mechanism 3d by a central shaft 3c passing through the rotating shaft 2c shown in t. 3
d, the support plate 3b is raised, and the magnetic disk 1 to be inspected is inserted from one direction, and the inner circumferential portion is placed on the outer circumferential portion 2d of the turntable 2a. Then, when the support plate 3b is lowered by a distance HP, each chuck piece 3a is pushed by the head of the turntable and opens outward, and the inner peripheral part is pressed by the bottom surface 3g of the chuck piece 3a, thereby clamping the magnetic disk. Here, since each hand piece has variations, an elastic body 3e is provided to ensure that the pressing force is uniform when pressed with the bottom surface 3g. Figure (c) shows the inner peripheral surface of the magnetic disk 1 pressed by the bottom surface 3g. The number of chuck pieces 3a is appropriately selected depending on the inch size of the magnetic disk 1, but in this case it is four, and the inside of the ring sandwiched between the circumference CI of the center hole of the magnetic disk and the outer circumference C2 of the turntable 2a is It is pressed by the bottom surface 3g. In addition, as a mechanical clamp mechanism, there is also used a mechanical clamp mechanism which has a different structure from the one described in I-I and the one described in Waka-F, but whose pressing method is almost the same.

Referring again to FIG. 2(a), the head assembly 4 consists of an inspection head 4a1 and a gimbal bar 4b, and in the case of protrusion inspection, a piezo element F4c is provided at an appropriate location (in the case of the figure, to the inspection, Rad). The carriage mechanism 5 consists of a moving part 5a that moves in the t-radial direction of the magnetic disk 1 by a drive motor 5c, and a support arm 5b fixed to this, and a gimbal bar 4b is attached to the support arm 5b. When inspecting the front and back surfaces of a magnetic disk at the same time, an inspection head 48', a gimbal bar 4b', a piezo element 40', and a support arm 5b' are provided on the disk side, and the moving unit 5
The same movement is caused by a. Rad 4a, 4 to the moved inspection
a' floats from the front or back surface of the magnetic disk 1 due to the air flow generated by rotation! - The inspection will be carried out at the same time.

[Problems to be Solved] Recently, in response to the increasing crystal density of magnetic disks, a small and lightweight thin film magnetic head has been developed, and this is also used in magnetic disk inspection apparatuses. Experiments have shown that the amount of floating on the thin film head is on the order of a minute sub-micron, and due to such minute floating@, the pressing force of the clamp mechanism described in t greatly affects the inspection results when inspecting protrusions. It has been revealed that

Figure 3 shows the L
An example of protrusion inspection data performed by changing the pressing force p of the chuck piece 3a is shown below. The horizontal axis represents the rotational speed of the magnetic disk, and the vertical axis represents the number of detected protrusions. Curve (A) shows the case when the pressing force p is the standard, curve (0) shows the case when p is made larger, and curve (c) shows the case when p is made smaller. The number of protrusions gradually decreases and settles at a constant value as the speed increases, and as the speed decreases, the float of the inspection head decreases, qualitatively indicating that even the smallest protrusions can be detected. It is shown in However, each curve has a different number of detected particles at the same rotation speed, and curve (0) has a larger number of detected particles than curve (A).
C) The number of detections is small. It has been recognized that such a difference in the number of detected particles occurs near the inner peripheral portion of the magnetic disk. The reason for the difference in the number of detected objects is considered to be that the pressing force p causes a slight distortion near the inner circumferential portion of the magnetic disk, and the convex portion is detected as an apparent upper protrusion. Possible causes of this distortion include that the pressing force p is excessive, and that there are gaps between the chuck pieces 3a so that the pressing force p tends to be uneven. On the other hand, in order to accurately detect the protrusion, it is effective to reduce the pressing force p for the time being. However, in order to stably clamp a magnetic disk rotating at high speed, a certain amount of pressing force p is required.

Therefore, in order to reduce the pressing force p, a method can be considered in which the two-dimensional ramp force is maintained comprehensively by using the air suction force that does not cause minute distortion.

In accordance with the above idea, an object of the present invention is to provide a magnetic disk clamping mechanism that reduces the pressing force of a mechanical clamping mechanism by using air adsorption force, thereby reducing minute distortions occurring in the magnetic disk. It is.

[F-stage to solve the problem] This invention includes a turntable that rotates with a magnetic disk to be inspected placed thereon, a rotating shaft that rotates the turntable, a central axis passing through the center of the rotating shaft, and This is a clamping mechanism in a magnetic disk inspection device that is coupled to a central shaft and includes a mechanical clamp mechanism that clamps a magnetic disk to a turntable. A ring adsorption path is provided on the turntable. Further, a rotating ring having a plurality of radial injection holes that injects internal air outward by rotation to generate negative pressure inside is fixed to the rotating shaft.

The suction groove and the injection hole are connected through a through hole, and the magnetic disk is suctioned by the suction force generated by the negative pressure. A pressing force adjustment mechanism is provided between the rotating shaft and the central shaft to reduce the pressing force of the mechanical clamp mechanism in inverse proportion to an increase in adsorption force due to an increase in rotational speed.

■ The pressing force adjustment mechanism described above consists of two connectors fixed to the rotating shaft and the central axis, respectively, and at least two metal balls each having a suitable weight connected to the two connectors by a connecting arm. , and a spring that urges the two couplings r apart.As the rotational speed increases, the centrifugal force causes the metal ball to move outward and the central axis to rise, increasing the pressing force of the mechanical clamp mechanism. This reduces the

[Function] In the magnetic disk clamping mechanism having the above-mentioned configuration, the magnetic disk is clamped by the mechanical clamping mechanism while the rotation is stopped and the rotational speed is low. On the other hand, when the rotary shaft rotates, air is injected outward from the injection hole to generate negative pressure inside, and this negative pressure generates an air suction force that does not cause minute distortion in the suction groove of the turntable through the through hole. In other words, air suction is used for mechanical clamps. When the rotational speed increases and the air suction force increases, the pressing force adjustment mechanism decreases the pressing force of the mechanical clamp mechanism in inverse proportion to this.
Both maintain a substantially constant clamping force. The reduction in pressing force reduces minute distortions that occur in the magnetic disk.

■ In the pressing force adjustment mechanism described in -, at a rotating speed of 1, the metal ball is moved outward by centrifugal force by the ax, and the distance between the two joints r connected to the metal ball by the joint arm is adjusted by the spring. Approach against the urging force.

The two connectors are fixed to the rotating shaft and the central shaft, respectively, and since the rotating shaft is immovable, the pressing force of the mechanical clamp mechanism connected to the central shaft is reduced by 25t.

As a result, when the micro-distortion of the magnetic disk is reduced, the number of apparent protrusions caused by this is reduced in protrusion inspection, and only true protrusions are accurately detected. Further, for error testing of test data, etc., it is possible to reduce the amount of floating of the inspection head, and an improvement in inspection accuracy can be expected.

[Example 1] Figures 1 (a), (b), and (e) are an overall vertical sectional view, a partial perspective external view, and a diagram of a rotating ring of an example of a magnetic disk clamping mechanism according to the present invention. It is an explanatory diagram of the effect. However, although the mechanical clamp mechanism 3 used is the one explained in FIGS. 2(a) and 2(b), it can be applied to other structures as long as they use the same pressing method. In Figures (a) and (b), a ring-shaped suction groove 2e is provided on the outer peripheral surface 2d of the turntable 2a. Further, a rotating wheel 6 having a plurality of radial injection holes 6a as shown in FIG. 2(c) is fixed to the rotating shaft 2c. Adsorption groove 2e
and the injection hole 6a are connected by a through hole 6b. When the rotary wheel 6 rotates, centrifugal force causes internal air to be injected outward as indicated by arrow A in Figure (c), creating negative pressure inside. The negative pressure generates an air suction force that does not cause minute distortion in the suction groove 2e through the through hole 6b. Here, the diameter of the rotating wheel 6 is
In order to obtain a negative pressure of 1 minute, it is necessary to make the turntable considerably larger than the turntable 2a. Next, F of the rotating shaft 2c
A pressing force adjustment mechanism 7 is provided between the end and the central axis 3c of the mechanical clamp mechanism 3. The pressure adjustment mechanism 7 has a rotating shaft 2c.
and the central shaft 3c, respectively, and the two metal balls 7a-1, 7a-2 of appropriate ffl are connected to both connectors by the connecting arm 7c. A spring 7d is interposed between the two connectors to urge them apart. The number of metal balls may be three or more, but it is necessary that each metal ball has a good dynamic balance. In the installation and clamping work of the magnetic disk, as before,
1. The chuck piece 3a of the mechanical clamp mechanism 3 is raised by the elevating/lowering mechanism 3d, and the disc 1 is inserted from one side and the inner circumferential surface is placed on the outer circumferential surface 2d of the turntable 2a. The chuck piece 3a is lowered, and its bottom surface 3g presses the inner peripheral surface to clamp the magnetic disk.When the rotational speed of the rotating wheel 6 by the spindle motor 2b increases by 1, the attraction force of the attraction m2e increases. At the same time, the metal ball 7a- of the pressing force adjustment mechanism 7
1 and 7a-2 move outward due to centrifugal force. Due to this movement, the couplings r7b and 7b' approach against the biasing force of the spring 7d, but since the rotating shaft 2c is immovable, the central axis 3C rises by a minute distance ΔZ 11 and the chuck piece 3
The pressing force of a becomes low. Since this low pressing force is almost inversely proportional to the increase in air suction force, the magnetic disk 1 is clamped with a nearly constant force by both of them, regardless of the rotational speed. During inspection, the magnetic disk is rotated at a constant rotational speed and the inspection head is floated at a predetermined height, and the apparent protrusion is reduced due to the reduction of minute distortions, resulting in highly reliable inspection. .

[Effects of the Invention As is clear from the explanation in 1r below, this invention has
.

In this magnetic disk clamping mechanism, air adsorption force using the negative force produced by the rotating wheel is used to counter the pressing force of the mechanical clamping mechanism, and both clamp and rotate the magnetic disk, increasing the rotational speed. The pressing force adjustment mechanism reduces the pressing force of the mechanical clamp mechanism in inverse proportion to the increase in air adsorption force due to the increase in t, thereby reducing minute distortions that occur on the magnetic disk. The reliability of inspection data is improved by reducing the number of protrusions, and the inspection accuracy is expected to improve as the inspection head floats smaller and the darkness becomes smaller for error tests such as test data. There are many benefits that contribute to magnetic disk inspection, such as:

[Brief explanation of the drawing]

FIGS. 1(a), (b), and (e) are a vertical cross-sectional view, a partial perspective external view, and an explanatory view of the action of the rotating shaft, showing an overall embodiment of a magnetic disk clamping mechanism according to the present invention, FIGS. 2(a), (b), and (c) are vertical sectional views of the W1 main part of the magnetic disk protrusion inspection device and an example of the mechanical clamp mechanism, and views showing the suppressing surface of the magnetic disk, and FIG. 2 is a curve diagram showing an example of protrusion inspection data obtained by changing the pressing force of the mechanical clamp mechanism. 1... Magnetic disk, 2... Rotating mechanism, 2a
...Turntable, 2b...Spindle motor 2
c...rotating shaft, 2d...outer peripheral surface, 2e...
...Adsorption groove, 3...Mechanical clamp mechanism, 3
a... Chuck piece, 3b... Support plate, 3c...
・Central axis, 3d...L lifting/lowering mechanism, 3e・
...Elastic body, 3g...Bottom surface, 4...Head assembly, 4 a + 4 a'... Inspection head, 4b, 4
b'... Gimbal bar, 4 c + 4 c '... Piezo element r15... Carriage mechanism, 5a... Moving part, 5b, 5b
'... Support arm, 5C... Drive motor,
6... Rotating wheel, 6a... Injection hole, 6b...
・Through hole, 7... Push 11 force adjustment mechanism, 7 a-I
17a-2...metal ball, 7b, 7b'...coupling γ, 7c river coupling arm, 7d...spring.

Claims (2)

[Claims] (1) A turntable on which a magnetic disk to be inspected is mounted and rotates, a rotating shaft that rotates the turntable, a central shaft that passes through the center of the rotating shaft, and a central shaft that is connected to the central shaft and that rotates the magnetic disk. In a magnetic disk inspection device equipped with a mechanical clamp mechanism that clamps the turntable, the turntable is provided with a ring-shaped suction groove, and the rotating shaft is rotated to inject internal air outward to remove the internal air. A rotating ring having a plurality of radial injection holes that generate negative pressure is fixed, and the suction groove and the injection holes are connected through a through hole so that the magnetic disk is attracted by the attraction force generated by the negative pressure. , characterized in that a pressing force adjustment mechanism is provided between the rotating shaft and the central shaft to reduce the pressing force of the mechanical clamp mechanism in inverse proportion to an increase in adsorption force due to an increase in the rotational speed of the rotating shaft. A magnetic disk clamping mechanism. (2) 2 fixed to the rotating shaft and the central shaft, respectively.
a connector, at least two metal balls having an appropriate weight connected to the two connectors by a connecting arm, and a spring biasing the two connectors apart, 2. The magnetic disk clamping mechanism according to claim 1, wherein as the rotational speed increases, the metal ball moves outward due to centrifugal force and the central axis rises, thereby reducing the pressing force of the mechanical clamping mechanism.