Keyboard mask for general-purpose calculator
AssigneeW & G Instruments, Inc.
InventorsUwe L. Beckmann, Edmund Osterland
Life of this patent
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Abstract
In order to adapt a general-purpose calculator to specific tasks, the keyboard of that calculator is covered by a mask including a resilient membrane overlain by a rigid panel having cutouts registering with keys whose function is to be preserved. The cutouts receive extension keys glued or otherwise fastened to the membrane, depression of any extension key operating the underlying original key. The functions of the operative keys can be modified, in accordance with the contemplated use, by insertion of a stored-program cassette associated with the particular mask employed.
Claims9
A masking device for limiting the operation of a keyboard-equipped general-purpose calculator to a specific task, comprising:
- a flexible solid membrane emplaceable above at least a major portion of the keyboard of said calculator;
- a plurality of extension keys on said membrane positioned to register with selected calculator keys of said portion upon emplacement of said membrane on said keyboard;
- and
- a rigid panel above said membrane positioned to overlie the entire keyboard, said panel having cutouts penetrated by said extension keys, thereby enabling manual operation of any of said selected calculator keys by depression of the corresponding extension key.
In a general-purpose calculator having a housing equipped with a keyboard and provided with a slot for stored-program cassettes establishing operating connections between the keys of said keyboard and logical circuitry within said housing, the combination therewith of a masking device emplaceable on said keyboard for giving access to selected calculator keys only, and a stored-program cassette establishing operating connections only for the calculator keys accessible through said mask;
- said masking device including a flexible solid membrane positioned above at least a major portion of said keyboard containing the selected calculator keys, a plurality of extension keys on said membrane registering with said selected calculator keys, and a rigid panel above said membrane overlying the entire keyboard, said panel having cutouts penetrated by said extension keys, thereby enabling manual operation of any of said selected calculator keys by depression of the corresponding extension key.
Dependencies are inferred from the claim text.