04688933 is referenced by 107 patents and cites 50 patents.

A position determining system for providing electrical signals representative of the positions of a light source movable within a defined area. The system may be implemented for purposes of data entry or for purposes of object location or surveying. When embodied in a data entry tablet, the invention provides signals representative of the positions of a stylus movable within the area of the tablet and comprising first and second photodetectors spaced along a base line by a predetermined distance, and means associated with each photodetector and operative to provide a movable narrow field of view for each photodetector. Means are provided for monitoring the angular position of each of the fields of view with respect to the base line and for providing a signal indication of the respective angular positions. A stylus having a light emitter at the tip thereof is movable within the area of the tablet and provides light detachable by each of the photodetectors. Each of the photodetectors provides a respective signal when the field of view of the corresponding photodetector receives light from the emitter. Means are provided which are operative in response to the signal indication of the angular position of each of the movable means at which light from the emitter is respectively detected to provide a signal representing the position of the emitter within the area of the tablet.

Title
Electro-optical position determining system
Application Number
6/732864
Publication Number
4688933
Application Date
May 10, 1985
Publication Date
August 25, 1987
Inventor
James M Lapeyre
New Orleans
LA, US
Agent
Weingarten Schurgin Gagnebin & Hayes
Assignee
The Laitram Corporation
LA, US
IPC
G06F 3/03
G06K 11/06
G01C 3/00
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