Abstract: Provided is a hinge type thinly configured integrated type key top in which the strength, durability, operability and other required conditions of a hinge portion are optimally designed assuring easy manufacturing and assembling as well as key input device and computer using the same. It is an integrated type key top in which a plurality of key tops are integrated with a peripheral frame portion. Each key top has in the vicinity of both ends of its specified one side a portion deformably connected to the frame portion via a hinge portion which extends approximately in a linear shape of a specified width and a specified thickness. The key top, the hinge portions and the frame portion are integrated with one another and made of a resin material, while the hinge portion has a thickness t (mm) and a total width w (mm) which are set so that 8.ltoreq.20t+w.ltoreq.14 is satisfied in a range of 0.25.ltoreq.t.ltoreq.0.6 and 2.ltoreq.w.ltoreq.10.

Abstract: A method for forming a fine unevenness over a surface of a base plate (9) for a magnetic disc comprises the step of bombarding the surface of the base plate (9) with a jet of gas mixed with fine ice particles (4) that are formed by mixing a flow of fine pure water droplets from a spray (2) and a counter directed flow of nitrogen gas cooled by being bubbled through a quantity of liquid nitrogen held in a reservoir (6). The obtained unevenness can be controlled by varying the size of the ice particles, the jet pressure, the distance between the jet nozzle providing the size of the ice particle jet and the receiving surface of base plate (9), the duration of spraying and the spraying angle with respect to the base plate.