10 Inventions on keyboard key switch mechanism-arxiv

A keyboard the main input device for a computer. A standard computer keyboard comprises of a base stand, a membrane circuit board with pressure sensors and several keys with a key pressing mechanism. A standard keyboard has four sections on the keyboard, a text entry section, a navigation section, a numeric section and a function key section. Each section comprises of several keys. The number of keys may vary from keyboard to keyboard. A standard present day keyboard contains 101 keys. Some older keyboards were comprised of 81 keys. Laptop and portable computers may have less number of keys. Some special keyboards may have more number of keys. The keyboard key switch mechanism The key switches of the keyboard of a computer system are generally comprised of a key cap having a plunger, conductive rubber disposed above a membrane circuit and compressed by the plunger to trigger the membrane circuit causing it to produce an electric signal to the computer. Some key switches use springs. Some other keyboards use rubber domes or a dome sheet, which do the function of springs. When the user depresses the key button the spring or domes collapse. The key switch depresses the key stem, which actuates the button on the membrane circuit. When the user releases the button the springs or rubber domes push the button up to the rest position. Background problem Many computer keyboards use a flexible sheet of nonconductive material beneath the key caps in which the flexible sheet has molded dome portions at each key position to serve as a return spring. Although this mechanism is popular, it has some drawbacks. It is expensive and time consuming to manufacture. Secondly, a separate mold is required to be constructed for each different key layout. Solution provided by the patent George English disclosed a solution to the above problem (Patent 5212356, assignee-Key Tronic Corporation, issued May 1993). The invention uses parallel extruded ridges at desired intervals for each key row. The ridge domes have parallel front and real walls that are collapsible to give the spring effect to lift up the depressed switches. The bottom surface of the bridging crown has an actuation keel of a conductive material, which actuates the keyswitch when the key is depressed. This invention has the advantage that the same rubber sheet can be used with different layout of keyboards. TRIZ based analysis It is desirable to …