JPH09145328A - Measuring device for levitation amount of magnetic recording apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a measuring device in which only a sensor measuring part making use of FTR(frustrated total reflection) can be formed at a magnetic head support system so as to be miniaturized by a method wherein a light-emitting part and a light-receiving part are installed at a guide arm which protrudes on a load arm. SOLUTION: A guide arm 7 protrudes up to a magnetic head slider 2 on a load arm 3, and a rectangular prism 4, a light-emitting element 4 and a photodetector 6 are mounted. A luminous flux 10 which is generated from the element 5 is reflected by the prism 4, and it is incident on a sensor measuring part 12 in such a way that its angle of incidence becomes a critical angle or higher by a diffraction grating. When the levitation amount of the measuring part 12 and that of a magnetic disk 1 are large, the luminous flux 10 is reflected totally and diffracted so as to be guided to the photodetector 6 as a luminous flux 11. When the levitation amount is at the wavelength or lower of light so as to reach a region in which evanescent waves ooze, the luminous flux 10 is absorbed by the disk 1, and the quantity of light of the luminous flux 11 is changed with reference to the levitation amount due to FTR. Then, the levitation amount can be measured by a computing circuit 9 by making use of it.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flying height measuring apparatus utilizing frustrated total reflection as a method for measuring a minute gap of a slider having a magnetic head mounted in a magnetic recording apparatus.

[0002]

2. Description of the Related Art As a prior art, Japanese Patent Application Laid-Open No. 3-212868 discloses an apparatus in which a sensor in which all of a light emitting section, an optical path and a light receiving section are optically integrated is mounted on a magnetic head slider. . As another method, as disclosed in Japanese Patent Laid-Open No. 3-54405, only the optical path is mounted on the magnetic head slider, and the light emitting section and the light receiving section are installed outside the device, and the optical path, the light emitting section and the light receiving section are installed. A device that connects the parts with an optical fiber has been introduced.

[0003]

Among the conventional techniques, in the method of optically integrating a sensor, it becomes difficult to integrate all of the light emitting portion, the optical path, and the light receiving portion when the magnetic head slider is downsized. In addition, since the output light amount of the light emitting unit is not stable due to the influence of the return light, there is a drawback that an error occurs in measurement.

On the other hand, the method of connecting the optical path to the light receiving portion and the light receiving portion with an optical fiber has a drawback that the optical fiber affects the spring rigidity of the load arm and the gimbal.

It is an object of the present invention to provide a flying height measuring device which can be constructed so as to be compatible with a magnetic head slider for miniaturizing a sensor using an FTR.

[0006]

In order to achieve the above object, the present invention provides a magnetic head slider by providing a guide arm projecting above a load arm and installing a light emitting portion and a light receiving portion on the guide arm. Only the sensor measurement unit is formed on the magnetic head support system including the load arm.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION A first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a perspective view showing the entire configuration of the present invention, and FIG. 2 is a side view showing the main measurement part in FIG. In FIG. 1, 1 is a magnetic disk, 2 is a magnetic head slider integrated with a sensor measuring unit 12, 3 is a load arm for supporting the magnetic head slider 2, 7 is a guide arm for mounting the load arm 3, 4
Is a rectangular prism that reflects the light beam 10 oscillated from the light emitting element 5 and the light beam 11 from the sensor measurement unit 12, 8 is a circuit for driving the light emitting element 5, and 9 is the flying height from the signal from the light receiving element 6. A circuit to be obtained, 13 is a diffraction grating for inputting and outputting the light fluxes 10 and 11 from the sensor measurement unit.

The operation of the first embodiment of the present invention thus constructed will be described. In FIG. 1, the guide arm 7 projects from the portion where the load arm 3 is attached onto the load arm 3 to the magnetic head slider 2.
A rectangular prism 4, a light emitting element 5, and a light receiving element 6 are mounted on the guide arm 7. The light beam 10 oscillated from the light emitting element 5 is reflected by the rectangular prism 4 and is incident on the sensor measuring section 12 formed on the magnetic head slider 2 by the diffraction grating 13 shown in FIG. It is incident. When the incident angle θ is greater than the critical angle, the light is totally reflected. At this time, at the boundary between the sensor measuring unit 12 and the air, the evanescent wave seeps out to the air side up to a region of about the wavelength of light. When the flying heights of the sensor measuring unit 12 and the magnetic disk 1 are sufficiently large, the light beam 10 is totally reflected, diffracted by the diffraction grating 13, and then reflected by the right-angle prism to be guided to the light receiving element 6 as a light beam 11. Light flux 11 at this time
Let L ₁ be the amount of light. However, when the levitation amount of the magnetic disk 1 and the sensor measurement unit 12 becomes equal to or less than the wavelength of light and reaches the area where the evanescent wave exudes, the light beam 10 is absorbed by the magnetic disk 1 and the light amount of the light beam 11 is as shown in FIG. It changes with the flying height. This optical phenomenon is called frustrated total reflection (FTR).
On the contrary, when the light amount of the light flux 11 at the time of FTR is L ₂ , L ₂ and L ₁ are detected by the light receiving element 6 and L ₂ / L is calculated by the flying height calculation circuit 9.
The flying height can be measured by obtaining L ₁ .

The flying height measuring device constructed as described above also measures the behavior of the magnetic head slider 2 during a seek operation.
Measurement can be performed by attaching the guide arm 7 to the seek motor 14 and seeking as shown in FIG. In addition, the diffraction grating 13
Instead of the above, the light beam 10 can be similarly incident on the sensor measurement portion at the incident angle θ by using the micro prisms 15 and 16 as shown in FIG. Further, when noise is generated in the magnetic disk device, the outputs of the light emitting element 5 and the light receiving element 6 are not stable. Therefore, as shown in FIG. 7, the light emitting element 5 and the light receiving element 6 are placed outside the magnetic disk device and light is emitted between them. If the fibers 17 and 18 are connected, a flying height measuring device resistant to noise can be constructed.

[0010]

According to the flying height measuring apparatus of the present invention, the guide arm projects above the load arm, so that the light emitting element and the light receiving element can be installed on the guide arm. Therefore, since only the minimum necessary sensor measuring portion can be formed in the magnetic head support system including the magnetic head slider and the load arm, the flying height can be measured without applying an external force to the magnetic head support system.

[Brief description of the drawings]

FIG. 1 is a perspective view illustrating an overall configuration of the present invention.

FIG. 2 is a side view of a sensor measurement unit.

FIG. 3 is a characteristic diagram showing the relationship between the flying height and the reflectance.

FIG. 4 is a perspective view of a magnetic head slider with a sensor measurement unit.

FIG. 5 is a front view illustrating the configuration during a seek operation.

FIG. 6 is a side view of a sensor measurement unit.

FIG. 7 is a perspective view of the overall configuration of the present invention when noise countermeasures are taken.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Magnetic disk, 2 ... Magnetic head slider, 3 ... Load arm, 4 ... Right angle prism, 5 ... Light emitting element, 6 ... Light receiving element, 7 ... Guide arm, 8 ... Light emitting element drive circuit, 9
... Flying height calculation circuit, 10, 11 ... Luminous flux, 12 ... Sensor measuring section.

Claims (2)

[Claims] 1. A measuring device that utilizes an evanescent wave generated when light is totally reflected when measuring the flying characteristics of a magnetic head slider of a magnetic recording device, wherein a guide arm is projected to a position above a load arm. Thus, the flying height measuring device of the magnetic recording device, wherein the light emitting element and the light receiving element are installed on the guide arm. 2. The flying height measuring apparatus for a magnetic recording device according to claim 1, wherein an optical fiber is used as an optical path as a measure against noise in the magnetic recording device.