04531033 is referenced by 18 patents and cites 13 patents.

A keyboard for initiating switching functions or switching signals. Synchronizing pins coupled to four key members at the mutually adjacent crossing between them cause actuation of contact sets upon depression of the keyboard surface above each synchronizing pin. Actuation of at least two contact sets are necessary to initiate a switching function corresponding to the keyboard symbol at the position of surface depression. A light may be employed to visually indicate the symbol actuated.

Title
Keyboard for initiating switching operations or switching signals associated with respective symbols on the surfaces of the keys
Application Number
6/491894
Publication Number
4531033
Application Date
May 5, 1983
Publication Date
July 23, 1985
Inventor
Friedrich Wolf
Planegg
DE
Horst Widmaier
Grosshesselohe
DE
Theobald Schmid
Munich
DE
Agent
Baker Maxham Callan & Jester
Assignee
Hand Widmaier Fabrik Fur Apparate Der Fernmelde und Feinwerktechnik
DE
IPC
H01H 9/16
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