发明名称 Demonstration calculator for classroom use and the like
摘要 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.
申请公布号 US4154007(A) 申请公布日期 1979.05.15
申请号 US19770835416 申请日期 1977.09.21
申请人 JUDD, WALLACE P 发明人 JUDD, WALLACE P
分类号 G09B5/02;G09B19/02;G09B23/18;(IPC1-7):G09B19/00 主分类号 G09B5/02
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