1. Field of the Invention
This invention relates to a flying head slider which flies or floats at a microscopic distance above the surface of a moving recording medium, a method of producing such a flying head slider, and a magnetic disk unit provided with such a flying head slider.
2. Prior Art
One example of conventional flying head sliders for a magnetic disk unit is a so-called taper flat-type slider, as disclosed in U.S. Pat. No. 3,823,416, which has a pair of straight gas-bearing rails at opposite side portions thereof, each gas bearing rail having a flat surface portion, and a slightly-inclined surface portion at a gas inflow side. Formed between the two gas bearing rails is a bleed portion which has a sufficient depth so as not to perform a gas-bearing function. The actual depth of the bleed portion is not less than 100 .mu.m at the boundary between the bleed portion and the gas bearing rail.
U.S. Pat. No. 4,734,803 discloses another type of slider in which each gas bearing rail is greater in width (rail width) at a gas inflow portion thereof than at the remainder of this rail, and optionally, the gas outflow end portion of the gas bearing rail flares into a fan-shape so as to facilitate the mounting of a magnetic transducer.
Because of the straight configuration of the gas bearing rails, such conventional sliders are produced by forming a groove, serving as the bleed portion, in the slider body by a mechanical grinding process using a slicer or the like. Alternatively, such sliders are produced by fixedly bonding a flat plate, constituting a flying surface, to the slider body by a bonding material such as glass.
Recently, to meet a high-density design of the unit, it has been required to micronize the target flying height. As a result of the micronization of the flying height, it has been necessary to miniaturize the slider and to reduce a dimensional tolerance of each part in order to decrease an allowable fluctuation of the flying height as well as variations in the flying height.
As a result of the micronization of the flying height, the gas bearing function of the gas bearing rails has been increasingly affected or influenced by the compression properties of the gas, and there is a possibility that as a result of the miniaturization of the slider, there occur unstable flying behaviors due to deterioration of the stiffness of gas film and deterioration of vibration damping characteristics of the gas film.
Further, as a result of the micronization of the flying height and the miniaturization of the slider, it has been necessary to reduce the rail width of each gas bearing rail. The result is that it has become difficult to mount a film-type head on the outflow end of the gas bearing rail.
Further, in the slider of the type in which the rail width of the gas inflow portion of the gas bearing rail is greater than the rail width of the remainder of the rail, the gas bearing region at the gas outflow end portion is small. Therefore, the generation of the pressure at this portion is small, and the rigidity at the outflow end portion is reduced not only in a pitching direction of the slider but also in an upward/downward direction and a rolling direction, which results in a problem that the fluctuation of the flying height becomes larger as compared with the conventional taper flat-type slider.
Further, in the case where the slider is formed by a mechanical grinding process, it is difficult to control the dimensional tolerance on the order of micron meters, and the slider can be chipped during the machining.
Still further, in the case where the slider is formed by fixedly bonding together a slider body and a flying surface portion which are separate from each other, there are encountered problems, such as an error in positioning of the bonded two members relative to each other, deformation of the flying surface, and difficulty of mass-productivity.
Thus, in the conventional sliders and the conventional methods of producing such sliders, there have been encountered problems with respect to the flying stability and the flying dynamic characteristics (particularly, the pitching stiffness and the vibration damping characteristics of the gas bearing), and there have also been problems with the precision and the mass-productivity.