[54] BAR CODE ACQUISITION UTILIZING MOIRE PATTERNS
[75] Inventors: Emanuel Marom; Joseph Katz, both of Stony Brook, N.Y.
[73] Assignee: Symbol Technologies, Inc., Bohemia, N.Y.
[21] Appl. No.: 681,601
[22] Filed: Apr. 8, 1991
[51] Int. CI.* G06K 9/00; G06K 7/10
[52] U.S. CI 235/462; 382/1
[58] Field of Search 235/462, 467; 382/1
[56] References Cited
U.S. PATENT DOCUMENTS
4,025,898 5/1977 Shaw 382/4
4,387,297 6/1983 Swartz et al 235/462
4,541,113 9/1985 Seufert et al 384/4
4,758,717 7/1988 Shepard et al 235/472
4,760,248 7/1988 Swartz et al 235/472
4,873,426 10/1989 Sarna et al 235/462
4,933,538 6/1990 Heiman et al 235/462
4,988,852 1/1991 Krishnan 235/462
5,086,215 2/1992 Carsner et al 235/462
5,120,940 6/1992 Willsie 235/462
FOREIGN PATENT DOCUMENTS
39162 2/1986 Japan 234/462
A bar code detector or acquisition arrangement for detecting the presence and location of a bar code pattern in a field of view. The bar code pattern detector is not designed to decode a bar code pattern, but merely to be sensitive to and detect the presence of a bar code pattern or patterns so that a conventional bar code scanner can then be activated to perform a decoding operation thereon. The present invention is based upon the generation of Moire patterns, and includes an electro-optic system for detecting and locating a bar code pattern in which an image of a field of view is projected onto a reference bar code pattern or an image thereof while producing relative rotation between the image of the field of view and the reference bar code pattern or image thereof. An optical detector detects the optical interaction of the image of the field of view with the reference bar code pattern or image thereof, including any Moire patterns generated thereby. A processor is coupled to the output of the optical detector for detecting the generation of any such Moire patterns, which are indicative of the presence and location of a bar code pattern or patterns in the field of view.
27 Claims, 4 Drawing Sheets
