Becton Dickinson and Company Limited

Becton, Dickinson Electronics Company

Barry W Mullins

Andrew Voge

Daniel R Sparks

J Arthur Cencel

A capacitance keyboard switch is provided which is of substantially reduced vertical dimensions for reducing in a keyboard the overall space requirements therefore. The switch of the invention has an overall height of only 0.750 inches (19.05 mm), and a length of travel of as much as 0.150 inches (3.81 mm). This is achieved by eliminating a housing for the switch altogether, utilizing a cooperating plunger-snap-in guide combination, and a single sheet movable capacitor plate which cooperates with a plate on the printed circuit board. In addition, the entire assembly is mounted and supported on the printed circuit board with the components snapped together without the use of separate hardware, such as screws or nuts.

Low profile keyboard switch

In a capacitive key for use in a keyboard, an operator depresses a plunger which alters the separation between the plates of a capacitor, thereby altering its capacitance. It is desirable to provide plunger overtravel which permits further depression of the plunger after the capacitor has been altered. In the present invention a portion of the movable capacitor plate is formed into a spring which elastically deforms after the capacitor has been altered, to permit overtravel of the plunger.

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Glendora, CA, United States of America

Barry W Mullins