United States Patent  [ii] Patent Number: 4,846,694
Erhardt  Date of Patent: Jul. 11, 1989
 COMPUTER CONTROLLED, OVERHEAD PROJECTOR DISPLAY
 Inventor: Heinrich S. Erhardt, Downington, Pa.
 Assignee: Image Storage/Retrieval Systems, Inc., West Trenton, N.J.
 Appl. No.: 208,923
 Filed: Jim. 20, 1988
 Int. CI." G03B 21/00
 U.S. CI 434/365; 353/31;
353/42; 353/122; 353/DIG. 3; 340/707;
 Field of Search 434/365; 353/31, 42,
353/122, DIG. 3, DIG. 5; 340/707; 364/520
 References Cited
U.S. PATENT DOCUMENTS
3,775,005 11/1973 Szabo 353/42
3,844,650 10/1974 Nicholson et al 353/DIG. 3
4,222,641 9/1980 Stolou 353/122
4,652,101 3/1987 Grunwald 353/DIG. 3
4,679,909 7/1987 Hamada et al 340/707
Apparatus for demonstrating the use of a computer terminal comprises a projection module supported on a standard overhead projector. The projection module includes a frame which is adapted to rest on an illumination window of the overhead projector. A transmissive liquid crystal display is mounted in the frame parallel to the illumination window such that an image on said liquid crystal display is projected by the projector. A transparent touch screen is also mounted in the frame overlaying the liquid crystal display. By means of a stylus, a user touches the touch screen and thereby designates desired text and/or images for subsequent display. Coupled to the decoder is a computer which retrieves the desired text and/or images which are then transmitted to a display driver. The aforesaid apparatus is most suited to demonstrate a computer terminal which has a touch screen for selecting text and/or images for display.
15 Claims, 8 Drawing Sheets