JPH10106130A - Non-contact electrostatic charge removing method for magnetic disk - Google Patents

Abstract

PROBLEM TO BE SOLVED: To earth electrostatic charge generated by a magnetic disk rotating by being loaded to the spindle of the rotational mechanism of an air bearing system in non-contact state. SOLUTION: A slope 22a is formed at the bottom surface of a spindle 22 and an electrode plate 31 is arranged by being separated with respect to the slope with a proper interval and a capacitance changing alternately is constituted between the electrode plate 31 and the slope 22a and an alternate current is induced in a current detector 32 by electrostatic charge Q charged on a disk 1 and the spindle 22 and then the major portion of the electrostatic charge Q is made to flow to an earth E with a cylinder 21 by detecting the polarity and the amplitude of the induced alternate current (i) with the current detector 32 and by generating an impression voltage in a voltage generating part 4 by respective detected data and by neutralizing static electrification while impressing the generated impression voltage on an air bearing 25.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for contactlessly removing an electrostatic charge generated on a rotating magnetic disk mounted on a spindle.

[0002]

2. Description of the Related Art A magnetic disk (hereinafter, simply referred to as a disk) used for recording information is inspected by a test apparatus for a physical defect of a recording medium and a quality of software storage performance. In the inspection, the disk is mounted on a spindle of a rotating mechanism and rotated, and test data is written / read to / from each track of the disk by a magnetic head, and the quality is inspected. Although there are various types of rotation mechanisms, it is said that an air bearing system in which the vibration of the spindle is not transmitted to the disk is suitable for recent high-density disks.

FIG. 3 shows an air bearing type rotating mechanism 2.
An example is shown below. The rotation mechanism 2 includes a cylinder 21 fixed to the base plate B, a spindle 22 that penetrates the cylinder 21, and a chuck head 23 that is coupled to a head of the spindle 22 and chucks the disk 1. from the air press fitting pipe 24 provided, air bearings 25 are formed by press-fitting the air a _r gap of the cylinder 21 and the spindle 22. In order to rotate the spindle 22, a fixed electrode 26 fixed to the inner wall of the cylinder 21 and wound with a coil is used.
1 and a motor 26 comprising a rotating magnet 262 provided on the side surface of the spindle 22.

Disc 1 rotating with spindle 22
The disk 1 and the spindle 22 coupled thereto generate an electrostatic charge (or static electricity) Q due to air flowing around the disk 1 along with the rotation. Spindle 22
Is insulated from the ground E by the air bearing 25, so that the charged electrostatic charge Q has no escape and accumulates gradually on the disk 1, and when it reaches a discharge voltage of several thousand volts, the surrounding air And discharge to nearby objects. Such a discharge not only adversely affects the inspection of the disk 1 but also is dangerous to the human body. In contrast, the rotating mechanism 2 is provided with a means for flowing the electrostatic charge Q to the ground E. This will be described with reference to FIG.

In FIG. 3, reference numeral 27 denotes a contact piece made of a metal brush, a metal plate, or the like. The contact piece 27 contacts the side or bottom surface of the spindle 22 and is connected to the base plate B by a lead wire. The electrostatic charge Q of the spindle 23 is collected by the contact piece 27, and flows to the ground E via the base plate B.

[0006]

The above-mentioned contact piece 27 has a disadvantage. That is, the contact piece 27 gradually wears due to the rotation of the spindle 22 and generates dust, and the quality of the disc 1 on which the dust adheres is degraded. Is reduced.
Further, the contact piece 27 wears unexpectedly quickly, so that it has to be replaced frequently. On the other hand, if there is a method of discharging the electrostatic charge Q in a non-contact manner, it is considered that the disadvantage of the contact method is eliminated and the method is effective. The present invention has been made in view of the above, and it is an object of the present invention to provide a method of flowing an electrostatic charge Q to the ground without contact.

[0007]

According to the present invention, there is provided a method for non-contact discharge of electrostatic charge of a magnetic disk, which solves the above-mentioned problems. A slope is formed by cutting in the direction, and an electrode plate is arranged at an appropriate distance from the slope to form a capacitance between the slope and the slope that changes alternately according to the rotation cycle of the spindle. A current detector is connected between the electrode plate and the ground, and a current induced by an electrostatic charge charged on the disk and the spindle flows to the ground through the current detector. The polarity and amplitude of the alternating current flowing are detected by a current detector, and the data of the detected polarity and amplitude is input, and a voltage generator is provided for generating an appropriate applied voltage to the air bearing. The air bearing is made conductive and most of the static charge is passed through the cylinder to ground.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the above-mentioned non-contact drainage method, an electrode plate arranged at an appropriate distance from a slope formed by cutting the bottom surface of a spindle in an oblique direction is provided with an electrode plate. In between, a capacitance that alternately changes according to the rotation cycle of the spindle is formed. The electrostatic charge charged on the disk and the spindle induces an alternating current through an alternating capacitance and a current detector connected between the electrode plate and the ground. The polarity and amplitude of the induced alternating current are detected by the current detector, and each detected data is input to the voltage generator, which generates an appropriate applied voltage to the air bearing and neutralizes most of the electrostatic charge. Is done. As described above, the adverse effect of the electrostatic charge on the inspection of the disk is eliminated, and since the electrode plate is not in contact with the spindle, the disadvantages of the conventional contact strip type contacting the spindle are eliminated.

[0009]

FIG. 1 shows an embodiment of a rotating mechanism 2 'to which the present invention is applied, and FIG. 2 is a waveform diagram of an alternating current detected by a current detector. In FIG. 1, the rotation mechanism 2 ′
Is substantially the same as the rotation mechanism 2 of FIG. 3 described above, the conventional contact piece 27 is removed, and instead, the bottom surface of the spindle 22 is cut obliquely to form a slope 22a. A voltage generator 4 is added. The current detecting section 3 is composed of an electrode plate 31 and a current detector 32. The electrode plate 31 is fixed to an insulating support rod 31a erected on a base plate B, and is arranged as close to the slope 22a as possible without contact. Then, the electrode plate 31 and the slope 22
Form a capacitance (capacitor) between a. Electrode plate 31
The interval between the slope 22a and the slope 22a alternately changes every cycle by the rotation of the spindle 22, so that the capacitance of the capacitor alternately changes accordingly. The voltage generation unit 4
It comprises a C power supply 41, a voltage converter 42 and a voltage applying plate 43,
DC power source 41 is assumed to generate a DC voltage HV, a voltage application plate 43 is inserted into the appropriate locations of the press-fit pipes 24, arranged to touch the air A _r to be press-fitted. On the other hand, the relationship between the voltage of the electrostatic charge Q of the disk 1 and the applied voltage suitable for making the air bearing 25 conductive against the voltage is checked in advance, and the voltage converter 42 has the DC power supply 41 A conversion function for converting the DC voltage HV into an appropriate applied voltage is provided.

Hereinafter, a non-contact discharge method of electrostatic charges will be described with reference to FIGS. In FIG. 1, the chuck head
The disk 1 that is chucked and rotated by the
Occurs, and the disk 1 and the spindle 22 are charged. An alternating current i is induced by the charged electrostatic charge Q and flows to the ground E via the current detector 32. The current detector 31 detects the polarity and amplitude of the alternating current i.

FIG. 2 shows an example of the alternating current i. When the electrostatic charge is positive with respect to the ground E, the sine waveform i on the positive side in the figure is shown.
A _+, - when the pole - side sinusoidal i _- a. However, both sinusoidal i _+, i _-, respectively DC currents i _a, i _b
Is superimposed. The current detector 31 outputs a bi-sine waveform i ₊ , i ₋
, And the amplitudes + A _m and −A _m of each of them are detected, and these detected data are input to the voltage converter 42. When each data is input to the voltage converter 42, the DC voltage HV of the DC power supply 41 is converted into an appropriate applied voltage by the conversion function and applied to the voltage applying plate 43, and the press-fit air _Ar is charged. Is largely neutralized.

[0012]

As described above, the non-contact electrostatic charge removing method of the present invention neutralizes the electrostatic charge charged on the magnetic disk and the spindle by the press-fit air charged to the opposite polarity. The system has no drawbacks such as abrasion and dust unlike the conventional contact system, and has the effect of contributing to the stabilization of disk inspection by the air bearing type rotating mechanism and the efficiency of maintenance work of the rotating mechanism. Some are big.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an embodiment of a rotation mechanism to which the present invention is applied.

FIG. 2 is a waveform diagram of an alternating current detected by a current detector.

FIG. 3 is a configuration diagram of an air bearing type rotation mechanism 2 according to the prior art of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Magnetic disk, 2 ... Rotation mechanism of prior art, 2 '... Rotation mechanism of this invention, 21 ... Cylinder, 22 ... Spindle, 22
a ... slope, 23 ... chuck head, 24 ... press-fit pipe, 25 ...
Air bearing, 26… Motor, 261… Fixed electrode, 262…
Rotating magnet, 27 contact piece, 3 current detector, 31 electrode plate,
31a ... insulating support rod, 32 ... current detector, 4 ... voltage generator,
41 ... DC power supply, 42 ... Voltage converter, 43 ... Voltage applying plate, B ...
Base plate, E: ground, _Ar : air, Q: electrostatic charge, ± A
_m ... amplitude.

Claims (1)

[Claims] An air bearing formed between the cylinder and the spindle, the cylinder comprising a cylinder fixed to a base plate and grounded, and a spindle which penetrates the cylinder and mounts and rotates a magnetic disk. As a result, the magnetic disk and the spindle are insulated from the ground, and the magnetic disk and the spindle are charged with electrostatic charges generated by the rotation of the magnetic disk. Direction to form a slope, and an electrode plate is disposed at an appropriate distance from the slope to form a capacitance between the slope and the slope that changes alternately with the rotation of the spindle. A current detector is connected between the electrode plate and ground, and the polarity and amplitude of the alternating current induced in the current detector by the alternating capacitance are detected. The air bearing is provided with a voltage generator that generates an appropriate pressurizing voltage when data of the detected polarity and amplitude is input, and the air bearing is made conductive by application of the applied voltage. A method for non-contact removal of electrostatic charge on a magnetic disk, characterized by neutralizing the electrostatic charge.