JPS6391503A - Apparatus for measuring head levitation gap - Google Patents

Abstract

PURPOSE:To perform highly accurate measurement inclusive of dynamic measurement, by subjecting the lights reflected by a levitation head to multiple interference on both of the surface of a head slider and that of a transparent disc to emphasize a specific wavelength. CONSTITUTION:The white light from a white light source system 10 is allowed to irradiate a head H in a levitated state through a disc 30 to form an image by an image forming system 13. The arbitrary part of this image is taken out to a measuring system 2 by an aperture 20 and spectrally diffracted by a prism 21 to be further again formed into an image on a unidimensional light receiving element 23 by a converging lens 22. Since the light passing through the spectral prism 21 is spectrally diffracted spatially corresponding to a wavelength, by receiving said light by the unidimensional light receiving element, spectrum intensity distribution can be detected at once. That is, since the light reflected by the head H and passing through the aperture 20 is emphasized by the multiple interference between the surface of a head slider and that of the transparent disc 30, the gap of the head H can be precisely measured.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a head flying gap measuring device, and more specifically, it measures the flying gap of a floating magnetic disk head more accurately and continuously in real time. The present invention relates to the configuration of a new gap measurement measurement device that can be implemented in the following manner.

Technical Background and Problems of the Invention One type of external storage device for relatively small computer systems is a so-called fixed disk device.

This fixed disk device has a relatively high storage density, and its use has expanded to meet the demands for large-volume processing of information accompanying advances in hardware and software in recent years. ing.

A fixed disk device is characterized by being constructed by housing a magnetic recording medium and a magnetic head in one container, thereby enabling high-density recording by precisely setting the positional relationship of each member.

Another major feature of the fixed disk device is the gas bearing structure. The detection surface of the magnetic head, that is, the head slider, is raised above the recording surface of the disk by the airflow generated by the rotation of the magnetic disk, which is the recording medium, and when it stops, it comes into contact with a predetermined non-recording area on the storage medium. - The holding structure avoids substantial wear of both.

The gap between the floating head and the recording medium used in such fixed disk devices is extremely small, less than 1 μm, and many methods have been proposed to measure this minute gap in product management or development. There is.

Problems to be Solved by the Invention The typical floating head gap measurement method that has been used in the past involves floating a floating head on a rotating transparent glass disk or the like, and shining white light onto the slider surface of the head. There is a method of irradiating it and observing the interference color due to white interference.

That is, in this method, the flying state of the flying head is observed with a normal microscope, and the flying gap is evaluated by comparing it with a standard color-gap comparison table prepared separately [See, Lin and Earl, F, Sullivan, "Thin Film Measurement". "Application of white light interferometry to" IBM. Research Development, Vol. 116, p. 269 (1972) (C.

Lin and RIF, 5ullivan, “An
Application of White Lig
ht Interferometry in Th1n
Film IJeasurements” IBM
J, RES, Develop, Vol, 16. p
269 (1972').

Although this method has the advantage of being simple and requires relatively short measurement time, it has the problem that color discrimination accuracy rapidly decreases in areas where the gap is 0.3 μm or less.

Therefore, as a method for measuring even smaller gaps with higher precision, an optical interference intensity measurement method using monochromatic light has been proposed, which is applied to the low flying gap region.

Two typical methods have been proposed for this measurement method. One of them is the optical interference intensity at a single wavelength (λ)... (1) However, S l = S o x N + N1: Reflectance of transparent disk S2 = (SO31)XN2 N2: Head Since the reflectance of the air bearing surface can be expressed as So = incident light intensity - a single wavelength light source (for example Sea 1)
. This is a method of calculating the levitation gap from the intensity of light using a light source (e.g. M., Fleisher and C.
Lin “Infrared Laser Interferometer for Air Flow Separation Measurement” IBM J.D. Research Development, No. 18
Vol. 529 (1974) (J.

Fleischer, M. and Lin, C.
”Infrared LaserInterfe
meter for Measuring Air
-Bearing Separation” IBM J
, RES, Develop, Vol. 18. p5
29 (1974)).

However, since this method uses a specific single wavelength, a region (4d/λm1, where m is an integer) periodically occurs where the measurement sensitivity is extremely reduced with respect to the size of the gap to be measured. Therefore, it cannot be used as a general measuring instrument.

Another method using the same principle is to use a variable wavelength light source (for example, a monochromator) to find the wavelength at which the light intensity is maximum or minimum and calculate the floating gap. Maruyama "Spacing measurement device using wavelength scanning method" 1985 IEICE Division National Conference Nα58゜1985).

In this method, it is necessary to mechanically move a diffraction grating or the like to scan the wavelength, and one measurement takes several tens of seconds to several minutes. Therefore, there is a problem in that it is impossible to perform dynamic measurements that measure the flying clearance that changes continuously, such as when starting up or stopping, for example.

Furthermore, any method using optical interference requires a separate microscope to observe the levitation state using a method using white interference, and there is a problem in that the overall measurement system becomes heavy and large. In other words, in floating measurements, a floating head is placed below a rotating disk placed horizontally, so observation is usually done from above, and the measurement system overhangs the object to be measured. Therefore, an increase in the weight of the measurement system results in an increase in measurement errors due to vibration. However, as mentioned above, it has been difficult to reduce the weight of this type of measurement system.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a novel floating head gap measuring device that can solve the problems of the prior art described above and perform highly accurate measurements including dynamic measurements. A further object of the present invention is to provide a floating head clearance measuring device that is lightweight and easy to handle.

Means for Solving the Problems According to the present invention, there is provided a head flying gap measuring device for measuring the flying distance of a floating head, which measures the flying distance of a floating head on the slider surface of the head floating with respect to a transparent disk. a white light source that emits white light through the transparent disk; a first imaging optical system that forms an image of the slider surface of the head using reflected light from the head; and the first imaging optical system. spectroscopic means for spectrally dispersing at least a portion of the image formed by the system;
a second imaging optical system that forms an image of the light separated by the spectroscopy means on a predetermined surface; and a one-dimensional light receiving element that receives the image formed by the second imaging optical system on a light receiving surface. Provided is a head flying gap measuring device comprising:

In the measuring device configured as described above, white light from a white light source is irradiated via the transparent disk onto the slider surface of the head that is floating relative to the transparent disk. This white light is reflected by the slider surface and focused on a predetermined surface by the first imaging optical system.

When this imaged reflected light is separated into spectra using a spectrometer such as a prism, the reflected light is spatially separated according to wavelength. At this time, by arranging an aperture for the output light of the first imaging optical system and processing only a part of the formed image, it is possible to reduce the size of the subsequent structure. .

The reflected light separated by the spectroscopic means is further imaged again on the light receiving surface of the one-dimensional light receiving element by the second imaging optical system.

At this time, the re-imaged light is spatially separated according to wavelength by passing through a spectroscopic prism. Therefore,
The one-dimensional light receiving element allows electrical detection of the spectral intensity distribution of the light that has passed through the aperture.

On the other hand, the white light reflected by the floating head has the same spectral intensity distribution as the above equation (1) because a specific wavelength is emphasized due to multiple interference between the head slider surface and the surface of the transparent disk. Granted. Therefore, the gap between the heads can be evaluated by detecting the wavelength at which the spectral intensity at a certain position is maximum or minimum from the reflected light received by the one-dimensional light receiving element via the spectroscopic means.

This measurement can obtain measurement results by electrically processing the output of a one-dimensional light receiving element, so even if the gap between the floating heads changes continuously, it can be processed continuously. .

EXAMPLES The present invention will be specifically described in detail below with reference to the accompanying drawings, but what is shown below is only one example of the present invention.
This does not limit the technical scope of the present invention.

FIG. 1 is a diagram showing a schematic configuration of a head flying gap measuring device constructed according to the present invention.

In the figure, what is shown in the center of the figure is mainly composed of an objective lens system 12, an imaging lens system 13, and an eyepiece system 14 assembled to a support tube 11, and further includes an epi-illumination system 10. This is a so-called metallurgical microscope. Lighting system 10
is a half mirror 16 on the observation optical path of this metallurgical microscope 1.
It is configured to irradiate the object to be measured with white light from the observation side.

In addition, the imaging lens system 13 of this microscope 1 includes a prism 15.
is equipped with the eyepiece system 14 and the microscope 1 at the same time.
It is configured so that the image is also formed on the top of the

An aperture 20 is provided on the imaging surface at the top of the microscope 1, and a detection system 2 is formed through this aperture 20. The detection system 2 includes a spectroscopic prism 21, a focusing lens 22, a one-dimensional light receiving element 23, and a light receiving measuring device 24 arranged along the optical path.

On the other hand, the floating head H whose gap is to be measured is placed facing the objective system 12 of the microscope 1 via a rotating transparent disk 30. That is, when the transparent disk 30 rotates in the same way as a magnetic recording medium in use in a fixed device, the floating head H floats from the disk 30 with a small gap due to the airflow generated by the disk 30. do.

Note that the prism 21 only needs to have a dimension slightly larger than the through hole of the aperture 200. Therefore, when the target measurement area is 0.01 mm and the microscope magnification is set to 100 times, the hole diameter of the aperture 20 is 1 mm, and the prism 210 dimensions are slightly larger than that, in fact, 1 mm.
．． 5 mm is sufficient. This size is extremely small compared to each member constituting the microscope 1, and its weight can be virtually ignored. Further, the positional relationship between the prism 21 and the focusing lens 22 may be reversed.

A photodiode array or a one-dimensional CCD can be used as the one-dimensional light receiving element. Clock 4MHz
If a general 512 element is used as a CCD, 8KH
The spectral intensity can be easily detected by repeating z. Now, change the measurement wavelength range from 0.25μm to 0.
．． Assuming 75 μm, the minimum gap range that can be observed as described below is 0.0625 μm, and the resolution is 5 angstroms, which is sufficiently accurate.

In the measurement apparatus configured as described above, white light from the white light source system 10 is irradiated onto the head H in a flying state via the disk 30, and an image is formed by the imaging system 13. An arbitrary part of this image is taken out to the measurement system 2 by the aperture 20, separated into spectra by the prism 21, and further by the focusing lens 22.
The image is then re-imaged onto the one-dimensional light receiving element 23.

Since the light that has passed through the spectroscopic prism 21 is spatially separated according to its wavelength, the spectral intensity distribution can be detected at once by receiving this light with a one-dimensional light receiving element.

That is, the light reflected by the head H and passed through the aperture 20 is emphasized by multiple interference between the head slider surface and the surface of the transparent disk 200, so that a specific wavelength has the same spectral intensity as in equation (1). Get the distribution. Therefore,
The gap between the heads H can be evaluated by detecting that the spectral intensity at a certain position is maximum or minimum.

Although the prism 21 and the focusing lens 22 are used in combination here, a focusing prism 200 having both a prism function and a lens function may be used instead, for example, as shown in FIG. 2. Such a prism can be easily obtained by injection molding of plastic.

In addition, the transmittance of the material of a prism may be poor in the extremely short wavelength or long wavelength region, but in that case, a diffraction grating with flat spectral characteristics is used to condense light as shown in Figure 3. A concave diffraction grating 201 that can also be used can be used. In this case, a large diffraction grating is required to improve the spectral efficiency, so the measurement system becomes somewhat large, but the structure is simplified.

Furthermore, in a normal illumination system, the entire field of view is uniformly illuminated, but by illuminating only the slider surface that corresponds to the light-transmitting part of the aperture part, the power required for the light source can be saved. Can be done. Further, in this case, since the lamp house can be made smaller, the apparatus can be made smaller than a normal measuring apparatus using white interference.

Effects of the Invention As described above, in the present invention, the same members as the microscope optical system used in the conventional white light interference method can be used for the illumination system and the objective eyepiece system. Therefore, a visual observation system for visually observing the entire floating head can be constructed at the same time as the measuring device. Furthermore, since the white light interference measurement and the visual viewing optical system are shared, it can be constructed at low cost and easily.

In other words, the measurement system can be constructed by adding only a small number of parts and dimensions to the viewing optical system. Therefore, there is almost no increase in weight, and no special vibration countermeasures are required.

Furthermore, the measuring device according to the present invention enables high-speed and precise measurements that could not be achieved with conventional devices. In particular, since the detection process can be performed electrically, virtually continuous processing becomes possible. Therefore, it is possible to perform not only dynamic measurements such as starting and stopping of the floating head, but also gap fluctuations during one rotation, and disk dynamic measurements and measurements of gap fluctuations during one rotation.

The characteristics of the head flying gap measuring device according to the present invention have an extremely wide range of applications, such as being usable as is for basic research such as analyzing the influence of disk vibration.

[Brief explanation of the drawing]

FIG. 1 is a diagram schematically showing the configuration of an embodiment of a head flying gap measuring device constructed according to the present invention, and FIG. 2 shows a spectroscopic means and a second output of the device shown in FIG. 3 is a diagram partially showing a configuration example using a focusing prism that can be applied to the imaging optical system; FIG. 3 is a diagram showing a concave diffraction grating that can be applied to the spectroscopy means of the apparatus shown in FIG. It is a figure which partially shows the example of a structure using. (Main reference numbers) 10... White light source, 11... Support barrel, 12... Objective lens, 13... Imaging lens, 14... Eyepiece lens, 16... Half mirror-1 20... Aperture, 21... Spectroscopic prism, 22... Focusing lens, 23... One-dimensional light receiving element, 30... Transparent disk, H... Floating head, 200... Focusing prism, 201...Concave diffraction grating

Claims (7)

[Claims] (1) A head flying gap measuring device for measuring the flying distance of a floating head, which irradiates white light through the transparent disk onto the slider surface of the head that is floating relative to the transparent disk. a white light source, a first imaging optical system that forms an image of the slider surface of the head using reflected light from the head, and spectrally spectra at least a portion of the image formed by the first imaging optical system. a second imaging optical system that forms an image of the light separated by the spectroscopic means on a predetermined surface; and a primary optical system that receives the image formed by the second imaging optical system on a light-receiving surface. 1. A head flying gap measuring device comprising: an original light receiving element; (2) The head flying gap measuring device according to claim 1, wherein the white light source and the first imaging optical system are metallurgical microscopes. (3) The head flying gap measuring device according to claim 1, wherein the second imaging optical system is a condenser lens, and the spectroscopic means is a spectroscopic prism. (4) The head floating according to claim 1, wherein the second imaging optical system and the spectroscopic means are a condenser prism in which a condenser lens and a spectroscopic prism are integrally formed. Gap measuring device. (5) The head flying gap measuring device according to claim 1, wherein the second imaging optical system and the spectroscopic means are concave diffraction gratings with flat spectral characteristics. (6) The head flying gap measuring device according to any one of claims 1 to 5, wherein the one-dimensional light receiving element is a CCD image sensor. (7) Claim 1 further comprising an aperture between the first imaging optical system and the spectroscopic means that transmits only a part of the image formed by the first imaging optical system.
6. The head flying gap measuring device according to any one of items 6 to 6.