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Title:
Chalk screen image projector
United States Patent 3332317
Inventors:
Peckman, Eugene F.
Carlson, Arthur W.
Torrey, Frank R.
Publication Date:
07/25/1967
Assignee:
E H SHELDON & COMPANY
Primary Class:
Other Classes:
353/98, 434/408
International Classes:
G03B21/132
View Patent Images:
Foreign References:
GB572528A