1
Leo J Rodrique: Tactile membrane keyboard with asymmetrical tactile key elements. Rogers Corporation, Fishman & Dionne, January 8, 1985: US04492829 (107 worldwide citation)

A tactile or snap action membrane keyboard is presented wherein the tactile or snap action key elements are protrusions in a membrane sheet, the protrusions being asymmetrical to preprogram the collapse of the tactile element.


2
Rodrigue Leo J: Clavier tactile a membrane avec zones de contact asymetriques, Tactile membrane keyboard with asymmetrical tactile key elements. Flex Key Corporation, OGILVY RENAULT SENCRLSRL, CA1196991

-15- TACTILE MEMBRANE KEYBOARD WITH ASYMMETRICAL TACTILE KEY ELEMENTS Abstract of the Disclosure: A tactile or snap action membrane keyboard is presented wherein the tactile or snap action key elements are protrusions in a membrane sheet, the protrusions being asymmetrical to preprogram the collapse ...