Typewriting machines – Means auxiliary to typewriting function
Patent
1991-05-31
1993-03-09
Burr, Edgar S.
Typewriting machines
Means auxiliary to typewriting function
400180, 400473, 400719, B41J 2900
Patent
active
051921529
ABSTRACT:
An automatic switch actuator is disclosed which may be used to test press-to-actuate type switches--for example, the key actuated switches of a computer keyboard. In the illustrated embodiment of the invention, a system of electrically operated valves are used to apply four different fluid pressures to selected pistons of an array of pneumatic cylinders. Each cylinder is mechanically connected to a plunger which is oriented so as to contact a selected key in an array of keys (i.e., a keyboard). The four fluid pressures applied are: (1) sub-ambient ("vacuum") which is used to retract the plungers thereby permitting easy loading and unloading of units under test; (2) "atmospheric" which is used to rest the plungers directly on the keycaps thereby minimizing dynamic loading of keys during the test; (3) "low pressure" which is selected to lower the plungers onto the keycaps and subsequently to apply a predetermined force which should not cause switch actuation; and, (4) "high pressure" which is selected to provide the minimum acceptable force on the plunger required to cause key actuation. The key switches are monitored for actuation by a computer which computer may also be conveniently used to control the pneumatic cylinders.
REFERENCES:
patent: 3768622 (1973-10-01), Wood
patent: 4313273 (1982-02-01), Matthews et al.
patent: 4441833 (1984-04-01), Hasenbalg
patent: 4543000 (1985-09-01), Hasenbalg
patent: 4937964 (1990-07-01), Crandall
"Hasco Design Overview Jan. 2, 1991" Hasco Technology, Inc.
Baker Mark W.
Czarnek David J.
Klein Timothy E.
Podhaisky Todd D.
Silvestri James T.
Burr Edgar S.
Compaq Computer Corporation
Keirs Christopher D.
Yan Ren
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