JPS6267Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention is a floating magnetic head with a minute levitation amount used in magnetic disk devices, etc., and has a structure for extracting dynamic fluctuations in the minute levitation amount as an electrical signal. This invention relates to improvements to the magnetic head for measuring the amount of levitation.

First, a conventional magnetic head for measuring the amount of levitation will be explained with reference to the drawings. FIG. 1 is a perspective view of a conventional magnetic head for measuring the amount of levitation, and FIG. 2 is a sectional view showing the levitation state together with a magnetic disk. In the figure, 101 is a slider made of a non-conductive material, 102a, b, and c are slider floating surfaces, and 103 is four metal films, the surfaces of which form an electrode surface 104. Furthermore, this electrode surface 104
A protective film 105 made of a hard non-conductive material such as glass or quartz is placed over the slider floating surfaces 102a, b, and c. The thickness of the protective film is on the order of microns, and the surface 106 of the protective film is mirror polished. Further, each electrode surface 104 is independently electrically connected to four lead wires (not shown) on the back surface of the slider via a conductive thin film 107.

When measuring the amount of levitation using this magnetic head, the slider 101 is levitated above the magnetic disk surface 111 as shown in FIG. All you have to do is measure the capacitance between. That is, if the capacitances of the four electrode surfaces 104 are measured independently, the gap δ between each electrode surface 104 and the magnetic disk conductor surface 113 can be determined independently, and therefore the levitation amount h( The gap between the protective film surface 106 and the magnetic disk surface 111 is determined independently, and the floating amount distribution of the magnetic head is determined.

Incidentally, in this case, the relationship between the levitation amount h and the capacitance c on each electrode surface 104 is determined by the thickness of the protective film 105, the magnetic disk surface 111, and the conductor surface 11.
Since the relationship between h and c is strongly influenced by the distance of 3 and the stray capacitance of the lead wire, it is necessary to calibrate the relationship between h and c for each electrode of each magnetic head and each magnetic disk.

During calibration, it is necessary to measure h, but since the levitation amount of current magnetic heads is less than 1 μm,
Its accurate measurement must be based on interference colors. Next, the calibration method will be explained with reference to the drawings.

FIG. 3 is a sectional view showing a method of calibrating the magnetic head for measuring the amount of levitation, in which a glass disk 121 is rotated at a circumferential speed U instead of the magnetic disk to levitate the magnetic head for measuring the amount of levitation. If the magnetic head levitation surface is observed through the glass disk in this state, dynamic fluctuation components will be reduced to an averaged levitation amount due to the interference of light between the glass disk surface 122 and the protective film surface 106. Corresponding interference fringes result. At this time, the protective film surface 106 and the slider floating surfaces 102a, 102
Since light interference also occurs with the light beam b and interference fringes are generated, two types of interference fringes are observed as a mixture, making it impossible to measure the amount of levitation using interference colors.

Therefore, in the conventional levitation measurement, the electrostatic capacitance c of the magnetic head and the levitation amount h are calibrated as follows, taking advantage of the fact that the levitation amount depends on the circumferential speed U. That is, first, a normal magnetic head without electrodes or a protective film is manufactured to have the same dimensions as a magnetic head for measuring the amount of levitation, and the amount of levitation of this magnetic head is measured using the interference color with a glass disk to determine the levitation. Find the relationship between the amount h and the circumferential speed U. Next, using a magnetic head and a magnetic disk for measuring the amount of levitation, we measured the disk circumferential speed U and the electrostatic capacitance c.
Find the relationship between Thereafter, assuming that the magnetic head for measuring the levitation amount has the same levitation characteristics as a normal magnetic head, the relationship between the levitation amount h and the electrostatic capacitance c was determined using the circumferential speed U as a parameter.

As described above, in the conventional magnetic head for measuring the amount of levitation, the relationship between the amount of levitation h and the capacitance c had to be measured indirectly using another magnetic head. For this reason, there was a drawback that the calibration of the levitation amount h and the capacitance c was inaccurate.

In order to eliminate these drawbacks, the present invention removes the protective film from the floating surface of some sliders and uses that part to directly measure the flying height of the magnetic head for measuring flying height using interference colors. This will be explained in detail below with reference to the drawings.

FIG. 4 is a perspective view showing an embodiment of the present invention, and FIG. 5 is a sectional view thereof. 20 in the figure
1 is a slider 202a made of a non-conductive material;
b and c are independent floating surfaces of the slider, and in particular 202c is an independent floating surface with a minute width,
Due to its narrow width, almost no buoyancy force is generated. 203
are four thin metal films, and this surface is the electrode surface 204.
is formed. Furthermore, a protective film 205 made of a hard, non-conductive material such as glass or quartz is placed over the electrode surface 204 and the slider floating surfaces 202a and 202b by a method such as sputtering.
06 is mirror polished. However, the surface of the slider floating surface 202c has a structure without a protective film.

Furthermore, in this embodiment, a thin film 207 of conductive material is applied from the slider side surface 208 to the slider back surface 208.
09, one end of this thin film is connected to a metal film 203 forming an electrode, and the other end is electrically connected to a lead wire 210 at a slider back surface 209.

To measure the levitation characteristics using this, the slider 201 is levitated above the magnetic disk surface (not shown) as in the conventional case, and the electrode surface 204 of the slider and the surface of the conductor in the magnetic disk ( (not shown) may be measured. In this case, by measuring the capacitance of each of the four electrodes, the gap between the protective film surface and the magnetic disk surface on each electrode surface, that is, the levitation amount, can be calculated using the pre-calibrated relationship between capacitance and levitation amount. The quantities, including their dynamic fluctuation components, are determined independently.

Next, when calibrating the levitation amount and capacitance, if the embodiment of FIG. 5 is levitated on a glass disk and observed through the glass disk, the slider levitation surface 2
Interference colors or interference fringes are observed on 02c. In this case, since there is no protective film on the slider floating surface 202c, there is no color mixing with other interference colors as in the conventional case, and information corresponding to the static floating amount can be obtained.
Therefore, using this glass disk, it is possible to determine the relationship between the levitation amount h of the magnetic head for levitation amount measurement and the circumferential speed U at the head mounting track of the glass disk. By finding the time-average relationship between the levitation amount h and the capacitance c of the magnetic head for measuring the levitation amount, the levitation amount h and the capacitance c can be calibrated using the circumferential speed U as a parameter.

Here, since the slider floating surface 202c is lower than the surface of the protective film, almost no floating pressure is generated.
Since the width of the slider floating surface corresponding to 02c is extremely narrow, the pressure generated is extremely small and is ignored compared to the floating pressure generated on other floating surfaces, so there is no protective film on the floating surface 202c. There is no effect on the buoyancy characteristics.

In this embodiment, an independent levitation surface 202c that hardly generates levitation force is located at the center of the slider.
Although it is depicted as a tapered flat slider spanning the front and rear of the slider, its shape may be any shape as long as it generates almost no buoyancy force, and its position may be arbitrary. For example, for a magnetic head that has a plurality of floating surfaces with a small width at the rear of the slider, a protective film is not formed only on these multiple floating surfaces with a small width, but on all other floating surfaces. It is clear that the present invention can be applied by forming the same, and that similar effects can be obtained.

As explained above, according to the present invention, the levitation amount h and the capacitance C can be calibrated using the same magnetic head, which is far superior to the conventional method of calibrating using two types of magnetic heads. Accurate calibration is possible.

[Brief explanation of drawings]

Fig. 1 is a perspective view showing a conventional magnetic head for measuring levitation, and Fig. 2 is a perspective view showing a magnetic head with a magnetic disk.
3 is a sectional view of the magnetic head shown in FIG. 1 together with a glass disk, FIG. 4 is a perspective view showing an embodiment of the present invention, and FIG. FIG. In the figure, 201 is a slider, 202a,
b, c are slider floating surfaces, 203 is a metal film, 20
4 represents an electrode surface, 205 a protective film, 207 a conductive thin film, and 210 a lead wire.

Claims (1)

[Scope of utility model registration request] A magnetic head has an electrode surface on a part of the floating surface of the slider, and the floating surface and the electrode surface are covered with a protective film made of a hard electrically conductive material with a mirror-polished surface. A floating magnetic head characterized in that it has a structure in which an independent floating surface is formed without the above-mentioned protective film.