Optics: image projectors – Miscellaneous
Patent
1994-06-28
1995-04-04
Cuchlinski, Jr., William A.
Optics: image projectors
Miscellaneous
353DIG3, 434365, G03B 2100
Patent
active
054041864
ABSTRACT:
A hand-held calculator has a transparent window carrying a liquid crystal display as well as transparent number and function key locations such that when placed on an overhead projector, the calculator can be used to demonstrate to a classroom of students all operations performed in a sequence of mathematical operations. The plastic casing of the calculator has one or more small holes passing through the casing at corners, so that a string or line can be used to tether the calculator to the overhead projector, preventing damage to the calculator from a fall to the floor. A further feature of the calculator is a protrusion or foot at each corner of the back of the calculator casing, for holding the back surface of the calculator slightly above the light platform of the overhead projector, for cooling of the liquid crystal display by air passing between the light table and calculator.
REFERENCES:
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patent: 4652101 (1987-03-01), Grunwald
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patent: 4946274 (1990-08-01), Honda
patent: 5035502 (1991-07-01), Stokes
patent: 5041965 (1991-08-01), Chen
Cuchlinski Jr. William A.
Dowling William C.
Freiburger Thomas M.
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