Abstract: In order to save space and manufacturing costs a pull-off effect for the operation of a key should be achieved by using a single spring. Thus the spring must have an arc-like force vs. displacement characteristic having a maximum of force about on half-way of the key stroke. This is achieved by a meander-like shaped spring (1) of flat material having two end loops (2, 3) of equal height and one middle loop (4) of about twice this height, all these loops lying within the same plane. The mounted spring is pretensioned in two directions being perpendicular to each other and lying in said plane, the operating force being applied to the top (7) of the middle loop.

Abstract: In order to have a large flexibility of application with simultaneously a reasonable number of different piece parts for a so called transformer keyboard the key element is subdivided. A base (1) usable for all applications includes elements for the protection against rotation (14) and for fixing (13) it on a printed circuit board (6) without screws and without soldering operations, further elements to guide (18) the stem (2) and to limit its stroke. The stem receives a ferromagnetic core (4) within its guidance (21). The shape and the size of wall portions (2', 22) change in accordance with the desired raster of the keyboard wherein the key element is used. A cap (3) carrying the marking has the same shape for all stems and is connected to the stem in a detatchable manner (27, 33). Due to their small height these key elements are especially suited in applications for data terminal keyboards with an ergonomically good design.