JPS63282973A - Head and medium contact detector - Google Patents

Abstract

PURPOSE:To detect the actions of a floating type head slider with high accuracy by obtaining simultaneously the difference and sum of the output voltage of respective plurally divided electrodes. CONSTITUTION:The action of a floating type head slider 2 is machine, voltage converted by respective element pieces 18 and 19 of a piezoelectric element 10 divided into two, and appears as the change of the voltage at divided electrodes 11 and 12. The output voltage of the electrodes 11 and 12 is supplied to a differential amplifying group 20, a difference A-B of an amplifying output is equivalent to the rotation moment of the piezoelectric element 10 as the difference in the acceleration of the thickness direction added as element 18 and 19 and a sum output voltage of the electrodes 11 and 12 shows the means value of the acceleration of the thickness direction added to the element pieces 18 and 19. The slider 2 to flow and travel on a magnetic disk by an air flow 8 from outputs A-B and A+B-2E is brought into contact with a fine projection 6 and a dust 7 on the disk and at the time of the movement, the two-dimen sional action is detected.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a magnetic recording technology having a floating head slider that floats above a disk-shaped magnetic recording medium. Due to lubrication, the head travels floating in a minute gap on the order of sub-microns, and if the behavior of the head becomes unstable during travel, the head may come into contact with minute protrusions or dust on the medium.
The magnetic disk medium and head are damaged, information is destroyed, and the recording/reproducing function is lost.

Therefore, investigating the behavior of the floating head slider when the slider comes into contact with minute protrusions or dust on the magnetic disk medium is important in designing floating head sliders for magnetic disk drives that require high reliability. It is.

A conventional method for investigating the behavior of a floating head slider is to measure the gap between the slider and the medium using optical interference fringes. Although this method makes it possible to measure the absolute amount of variation in the gap between the medium and the slider, it has the disadvantage of being subject to limitations such as requiring a translucent slider.

Problems to be Solved by the Invention Therefore, in recent years, a method has been proposed for detecting acceleration by attaching a small piezoelectric element directly to a floating head slider (U.S. Pat. No. 4,532,802, October 6, 1985). Day).

As shown in Fig. 2, this method is based on a floating Hent slider 2 supported by a gimbal 4 attached to an arm 5. Two) piezoelectric elements 3 are mounted, and the behavior of the floating Hent slider 2 is detected by sending the output voltage from each piezoelectric element 3 to a separate detection circuit l.

In FIG. 2, reference number 6 indicates fine protrusions on the surface of the recording medium, reference number 7 indicates dust, and reference number 8 indicates air flow.

However, with this method, it is difficult to detect the behavior of the floating head slider 2 with high accuracy because there are large errors due to variations in the materials constituting the piezoelectric element 3 and variations in their adhesive strength.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a head/medium contact detection device that is capable of detecting the behavior of a floating head slider with high accuracy by mounting a single small piezoelectric element on a floating head slider. It is in.

Necessary Means for Solving the Problems The head/medium contact detection device of the present invention is a piezoelectric device mounted on a floating head slider used in a magnetic recording device having a floating head slider that flies above a magnetic disk medium. In a device that measures the behavior of a floating Hent slider using an element, the electrode on the surface opposite to the slider adhesive surface of the piezoelectric element that has the largest mechanical-electrical conversion coefficient in the thickness direction is divided into multiple parts, and the divided electrodes are It is characterized by the provision of a lead wire for voltage detection.

Furthermore, in the embodiment of the present invention, the electrode on the opposite side of the piezoelectric element to which the slider is bonded is divided into a plurality of parts, and the part of the piezoelectric element connected to the divided electrode is divided into a plurality of parts. By providing deep grooves, the piezoelectric element is divided into a plurality of element pieces. That is,
The difference from the prior art shown in FIG. 2 is that a portion of the same piezoelectric element is divided by groove processing, and electrode leads are attached to each electrode of the divided element pieces.

The depth of the above groove processing is 0.1 to 1 times the thickness of the piezoelectric element.
Preferably, it is doubled.

Function: In the head/medium contact detection device according to the present invention having the above-described configuration, by simultaneously calculating the difference between the output voltages of each of the plurality of divided electrodes and the sum of these output voltages, The magnitude and direction of applied acceleration can be detected.

EXAMPLES Hereinafter, the present invention will be described in detail with reference to the accompanying drawings, but the present invention is not limited thereto.

Embodiment 1 FIG. 1 is a perspective view of a floating head slider illustrating a first embodiment of the present invention, in which the same members as in FIG. 2 are given the same reference numerals.

A feature of the present invention is that a single piezoelectric element 10 having the maximum mechanical-electrical conversion coefficient in the thickness direction is mounted on the floating head slider 2 supported by the gimbal 4.

Piezoelectric element 10 is shown in detail in the enlarged view of FIG.

In FIG. 3, reference numerals 11 and 12 indicate an electrode divided into two parts facing the electrode 15 on the side bonded to the floating head slider 2, that is, on the opposite side thereof.

The electrodes 11 and 12 are connected to electrode leads 16.
．． 17 are provided. Furthermore, the portion of the piezoelectric element 10 coupled to the two-divided electrode 11.12 is separated by the groove 13 into two element pieces 18.19.

With this structure, the movement of the floating head slider 2 is mechanically-electrically converted by the element pieces 18 and 19 of the piezoelectric element 10, which is divided into two, and It appears as a change in voltage at 11.12.

FIG. 4 shows an example of the configuration of an amplifier circuit that detects a signal obtained from the piezoelectric element 10. The illustrated amplifier circuit is configured by five differential amplifiers 20 connected as illustrated, and A, B, E are connected to each electrode 11, 12, .
15.

The output voltage of this amplifier circuit, i.e. the divided electrode 11
．． The difference A-B in the output voltages of the electrodes 11 and 12 is the difference in acceleration in the thickness direction applied to the element pieces 18 and 19, that is, a force corresponding to the rotational moment of the piezoelectric element 3, and the sum of the output voltages of the electrodes 11 and 12 is A + B-2E represents the average value of the acceleration in the thickness direction applied to the element pieces 18 and 19.

In this example, two outputs A-B and A+B
-2E shows the two-dimensional movement of the floating head slider 2 when the floating head slider 2, which flies and travels above the magnetic disk due to the air flow 8, comes into contact with minute protrusions 6 and dust 7 on the magnetic disk and moves. can be calculated.

Embodiment 2 FIG. 5 is a perspective view showing a second embodiment of a piezoelectric element 10 according to the invention, with reference numbers 21, 22, 23 and 2.
4 indicates a quartered electrode, and reference numbers 25 and 26 are
A groove for dividing into four parts is shown, reference number 32 shows a lead wire attached to the electrode, and reference number 31 shows the electrode on the adhesive side. Also in this embodiment, the piezoelectric element 10
A portion of each element piece 27. is provided by grooves 25.26.
It is divided into 28, 29, and 30.

FIG. 6 shows an example of the configuration of the detection circuit used in the embodiment of FIG. 5, and is configured by connecting a plurality of differential amplifiers 20 as shown. A, B, C, D, and E indicate output signals of each electrode 21.22.23.24.31.

Because of this structure, the electrodes 21 .
At 22, 23, and 24, an output voltage corresponding to the movement of the floating head slider 2 is generated.

In the detection circuit of the second embodiment of the present invention shown in FIG.
9.30 is the average value of the acceleration in the thickness direction. Further, the output voltage differences A-B and A-C1A-D represent the difference in acceleration in the thickness direction applied to each element piece 27-28.27-29.27-30.

In this way, since the piezoelectric element 10 is divided into four parts in this second embodiment, the force in the thickness direction applied to the piezoelectric element 10 and the moment around the approximate center of the grooves 25 and 26 for dividing the piezoelectric element 10 into four parts correspond to Therefore, the three-dimensional movement of the floating head slider 2 can be calculated.

The present invention is not limited only to the above embodiments, and various modifications are possible. For example, the groove formed in the piezoelectric element 10 may be X-shaped, and the mounting direction and position of the piezoelectric element 10 can be arbitrarily selected.

As described in detail, by using the piezoelectric element and detection circuit of the present invention, the acceleration applied to the floating head slider can be detected with high accuracy using - number of piezoelectric elements.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a two-dimensional acceleration detection slider equipped with a piezoelectric element according to a first embodiment of the present invention, and FIG. 2 is a perspective view of a conventional two-dimensional acceleration detection slider equipped with a plurality of piezoelectric elements. , FIG. 3 is an enlarged structural diagram of the piezoelectric element shown in FIG. 1, FIG. 4 is a configuration diagram of a detection circuit used in the first embodiment of the present invention, and FIG. FIG. 6 is an enlarged view showing the structure of the piezoelectric element used in the second embodiment of the invention. FIG. 6 is a configuration diagram of the detection circuit used in the second embodiment of the invention. [Main reference numbers] 1...Detection circuit, 2...Floating head slider 3...Piezoelectric element, 4...Gimbal 5...
・Arm, 6...Minute protrusion 7...Dust,...Air flow 9...Detection circuit, 1
0... Piezoelectric element 11.12... Divided electrode 13... Groove for division 15... Adhesive side electrode, 16.17... Lead wire 18.19... Divided Element piece 20...differential amplifier

Claims (3)

[Claims] (1) In a head/medium contact detection device that measures the behavior of a floating head slider using a piezoelectric element mounted on a floating head slider that flies over a magnetic disk medium of a magnetic recording device, the largest machine in the thickness direction A head/medium contact detection device characterized in that an electrode of a piezoelectric element having an electric conversion coefficient on a surface opposite to a slider adhesive surface is divided into a plurality of parts, and a lead wire for voltage detection is provided on the divided electrodes. (2) On the surface of the piezoelectric element that faces the slider adhesive surface,
Provide a groove with a depth of 0.1 to 1 times the thickness t of the piezoelectric element,
2. The head/medium contact detection device according to claim 1, wherein the piezoelectric element is divided into a plurality of element pieces by the groove. (3) The difference in output voltage of the plurality of divided electrodes,
Claim 1 or Claim 1, characterized in that by simultaneously calculating the sum of the output voltages, it is possible to simultaneously detect the difference in acceleration acting on each piezoelectric element piece divided by the groove and the average value of the accelerations. The head/medium contact detection device according to item 2.