Demonstration calculator for classroom use and the like

Details Demonstration calculator for classroom use and the like Demonstration calculator for classroom use and the like

1977-09-21

1979-05-15

Grieb, William H.

Communications: electrical

Land vehicle alarms or indicators

Internal alarm or indicator responsive to a condition of the...

35 6, 35 30, 340711, 35DIG3, 340757, G09B 1900

Patent

active

041540077

ABSTRACT:
An electronic calculator having a liquid crystal display (LCD) which is supported on a transparent substrate so that light from an overhead projector or the like can be transmitted through the display to create an enlarged image of the numerals in the display that are made opaque by proper excitation of the LCD. A calculator supplied with such modified LCD wherein the rear surface of the LCD is parallel to the rear surface of the calculator case so that the case can be placed upon the projection plane of a conventional overhead projector, thereby permitting an instructor to manipulate the input keys to the calculator while simultaneously affording an enlarged view of the LCD to others in the classroom.

REFERENCES:
patent: 2841889 (1958-07-01), Coale et al.
patent: 3740717 (1973-06-01), Huener et al.
patent: 3789388 (1974-01-01), Medwin

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