JPH0533474B2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a floating head slider using negative pressure.
In particular, the present invention relates to a floating head slider using negative pressure that floats in an ultra-small gap used in a rigid magnetic disk device.

(Prior art and its problems) As the capacity of the floating head slider (hereinafter simply referred to as slider) for magnetic disk devices increases, the amount of floating head is becoming smaller and smaller, and currently it is several times the mean free path of a molecule of air. It has been miniaturized to a certain level. As is well known, the sliders that have been put into practical use so far are twin-barrel positive pressure sliders that have a tapered flat type dynamic pressure gas bearing surface that has a light load and good dynamic followability. However, since the air film rigidity of this positive pressure slider is approximately proportional to the pressing force, there is a certain limit to increasing the rigidity of the slider adopting the contact start/stop method. This is because increasing the pressing force increases the surface pressure of the slider, which poses a problem of wear during sliding contact with the recording medium. In order to overcome these problems, we have recently developed a next-generation slider, a floating head slider that utilizes negative pressure, which uses photolithography technology to create minute recesses within the air film lubricated surface of the slider to generate negative pressure. (hereinafter simply referred to as negative pressure sliders) are being actively researched. This negative pressure slider has the following features: (1) A highly rigid air film can be obtained despite a light load due to the push-pull action of positive pressure and negative pressure, and (2) Fluctuations in slider floating amount with respect to the slider's peripheral speed are small. It has the advantages of
This is the most promising slider for future large-capacity magnetic disk drives using thin-film media.

FIGS. 1a and 1b are a front view and a side view, respectively, showing an example of a conventionally proposed negative pressure slider. In the figure, reference numeral 1 is a positive pressure generating surface, reference numeral 2 is a cross rail surface, reference numeral 3 is a recess groove provided on the positive pressure generating surface, and reference numeral 4 is a reverse step surface that generates negative pressure, reference numeral 4 is a reverse step surface that generates negative pressure. Reference numeral 5 denotes a recess groove provided in the tapered portion of the front edge of the slider.
In order to prevent the negative pressure slider from contacting the recording medium during contact start and stop, the cross rail surface 2
It is characterized in that it is etched and has a step with the positive pressure generating surface 1, so that it is not on the same plane. Another feature is that a recess groove 5 is also provided on the positive pressure generating surface 1 in order to obtain stable flotation characteristics against flutters on the recording medium surface. In other words, the positive pressure generation distribution of the negative pressure slider is made high at the slider air inflow end and air outflow end, and the slider is
This is to give it a shape that supports it at points. Therefore, this negative pressure slider floats extremely stably both statically and dynamically.

Next, recently there has been an active development of small, large-capacity magnetic disk devices as files for OA equipment. For example, a small diameter recording medium such as 3.5 inches or 5 inches is used. In this type of device, the running speed of the recording medium cannot be high, so a negative pressure slider that quickly transitions from the boundary lubrication region to the fluid lubrication region in the low speed region is effective.
On the other hand, however, rotary actuators are often employed in such small magnetic disk devices in order to increase the reliability of the mechanism and reduce costs. In the case of the rotary actuator, since the magnetic head is given an azimuth angle, the floating head slider has a so-called yaw angle, and the lubricating gas flows into the slider as an oblique flow. Therefore, from the viewpoint of electromagnetic conversion characteristics, even when a negative pressure slider is employed, it is necessary to ensure that its floating amount does not depend on the yaw angle. However, the negative pressure slider shown in FIG. 1 has a drawback in that the amount of levitation decreases significantly with respect to this yaw angle. In other words, as the yaw angle increases, the positive load capacity generated by the negative pressure slider is significantly reduced, and at the same time, the negative load capacity, that is, the suction force, also increases slightly. The amount of buoyancy will decrease. Therefore, if a negative pressure slider is mounted as a magnetic head in a magnetic disk device that employs a rotary actuator, major problems will arise in its mechanical reliability and electromagnetic conversion characteristics.

(Object of the Invention) The present invention has been made in order to eliminate the drawbacks of the negative pressure slider described above, and its purpose is to reduce fluctuations in the amount of lift even if the yaw angle changes on the recording medium. The purpose of the present invention is to provide a negative pressure slider.

(Structure of the Invention) According to the present invention, a pair of positive pressure generating surfaces, a recess groove portion provided on the surfaces, and a step having a step with the positive pressure generating surfaces are not on the same plane as the positive pressure generating surfaces. A negative pressure floating head slider having a cross rail surface and a reverse step-shaped recess portion surrounded by the positive pressure generating surface and the cross rail surface in the air outflow portion,
A floating head slider utilizing negative pressure is obtained, wherein the recess groove provided in the positive pressure generating surface has a shape in which the width thereof becomes narrower as it goes from the air inflow side to the air outflow side.

(Example) The present invention will be described in detail below with reference to FIGS. 2 and 3.

FIGS. 2a and 2b are a plan view and a side view, respectively, showing an embodiment of the negative pressure slider of the present invention. In this embodiment, a recess groove 3 provided on a pair of positive pressure generating surfaces 1a is used.
The groove part a is variable in the longitudinal direction of the slider, and the width of the recess groove at the air outflow end is smaller than the width at the air inflow end, so that the recess groove width is narrower at the end in the air flow direction. This is what I did. Note that the cross race surface 2a, reverse step surface 4a,
The recess groove portions 5a provided in the tapered portion are each
This corresponds to the cross rail surface 2, reverse step surface 4, and recess groove portion 5 provided in the tapered portion shown in Figures a and b.

As is well known, the negative pressure slider has good lifting characteristics with respect to the running speed of the recording medium, so it is suitable for small magnetic disk drives from the viewpoint of contact start/stop characteristics. However, it is necessary to investigate whether a small magnetic disk device using a rotary actuator exhibits good levitation characteristics. In other words, this means clarifying the fluctuation in the amount of levitation due to the yaw angle of the negative pressure slider. Therefore, the influence of the yaw angle on the levitation characteristics of the negative pressure slider shown in FIG. 1 was investigated. The investigation method was carried out by numerically solving the modified Reynolds equation, which governs the levitation characteristics of a floating head slider operating at a levitation amount in the submicron range, using techniques such as the finite element method. FIG. 3 is a diagram showing the calculation result, which shows the decrease in the floating amount of the positive pressure slider and the negative pressure slider depending on the yaw angle. In the figure, the vertical axis is the minimum levitation reduction rate (the ratio of the levitation amount hmφ when the yaw angle is set to the levitation amount hm0 when the yaw angle is zero)
It shows. From the figure, it can be seen that in the case of the negative pressure slider, the minimum lift amount decreases due to the yaw angle more than in the winch-estor type positive pressure slider that has already been put into practical use. In other words, this shows that the negative pressure slider has a larger fluctuation in the amount of levitation due to the yaw angle, and when a negative pressure slider is installed in a device using a rotary actuator, its mechanical reliability is a major problem. I know what will happen. The reason why the floating amount of this negative pressure slider is greatly reduced compared to the conventional positive pressure slider is that physically, the positive load capacity is significantly reduced, and the negative pressure load capacity is slightly affected by the yaw angle. This happens due to two effects: However, the main factor is a significant decrease in the positive load capacity, and looking at the change in the slider positive pressure distribution depending on the yaw angle,
The positive dynamic pressure generated at the slider trailing edge has dropped significantly. Therefore, the pressure drop becomes a source of load capacity reduction. This corresponds to the fact that the wedge effect of the slider trailing edge portion is effectively reduced by the yaw angle, and the width of the positive pressure generating surface of the slider is narrowed. Therefore, in order to prevent a drop in dynamic pressure at this trailing edge portion, it is necessary to widen the width of the bearing surface at that portion.

In this embodiment, the recess groove 3a in the positive pressure generating surface 1a becomes narrower toward the air outlet end, so this is effectively equivalent to having a shape in which the width of the positive pressure generating surface widens toward the end. . Therefore, even if the lubricating gas flows into the slider surface as a two-dimensional oblique flow, no significant drop in dynamic pressure at the trailing edge portion will be observed. Further, since the negative pressure fluctuation due to the yaw angle is almost constant although it increases slightly, the load capacity fluctuation due to the yaw angle is consequently smaller than that of the conventional negative pressure slider. Therefore, in a magnetic disk device using a rotary actuator, stable levitation characteristics with small fluctuations in levitation amount can be obtained even if different yaw angles are applied to the negative pressure slider on the surface of the recording medium. Become.

Furthermore, in this embodiment, since the width of the positive pressure generating surface 1a itself is not changed, the reverse step surface 4a, which is the negative pressure generating surface, can be designed to be sufficiently wide. Therefore, it is also possible to generate sufficient negative pressure, and there is also the effect that extremely high air film rigidity can be obtained with an extremely light load.

Note that any modification may be made without departing from the spirit of the present invention; for example, the rate of narrowing at the end of the recess groove and the shape of the positive pressure generating surface may be optimized in each case; It goes without saying that the examples do not limit the scope of the invention in any way.

(Effects of the Invention) As described in detail above, in the negative pressure slider of the present invention, the width of the recess grooves provided on the pair of positive pressure generating surfaces is narrowed from the air inflow end toward the air outflow end. As a result, the width of the positive pressure generating surface becomes effectively wider toward the air outflow end, so that the drop in positive pressure is significantly alleviated, and therefore the decrease in the amount of levitation due to the yaw angle is suppressed. Furthermore, since the shape of the reverse step surface, which is the negative pressure generating surface, is not changed, there is an effect that extremely stable levitation characteristics can be obtained with little variation in negative pressure due to the yaw angle.

[Brief explanation of drawings]

1A and 1B are a front view and a side view, respectively, showing an example of a conventionally proposed negative pressure slider, and FIGS. 2A and 2B are a front view and a side view, respectively, showing an embodiment of the negative pressure slider of the present invention. The figure and FIG. 3 are diagrams showing a reduction in the floating amount of the positive pressure slider and the negative pressure slider depending on the yaw angle. In the figure, 1, 1a... Positive pressure generating surface, 2, 2
a... Cross rail surface, 3, 3a... Recess groove provided on the positive pressure generating surface, 4, 4a... Reverse step surface, 5, 5a... Recess groove provided on the tapered surface.

Claims (1)

[Claims] 1 A pair of positive pressure generating surfaces, a recess groove provided on the surfaces, a cross rail surface having a step with the positive pressure generating surface and not on the same plane as the positive pressure generating surface, and a In a negative pressure floating head slider having a reverse step-shaped recess surrounded by a positive pressure generating surface and the cross rail surface, the recess groove provided in the positive pressure generating surface has a width that varies from the air inflow side to the air outflow side. A floating head slider utilizing negative pressure, characterized in that it has a shape that becomes narrower toward the side.