Patent Number: 6,332,574

Title: Method of reading bar code

Abstract: A method of reading a bar code having guard bars at both sides thereof without fail even if the bar code image is highly distorted. An image region taken in by a CCD camera is scanned in horizontal and/or vertical directions to find out a first guard bar in the bar code. Then, a first scanning line for reading the bar code is set in a direction perpendicular to the first guard bar. The bar code is scanned along the first scanning line. If the first scanning line goes out of the bar code region, the first scanning line is traced back to a bar which is last read. Another scanning line starting from the last read bar and extending perpendicularly thereto is set to read the rest of the bar code. This process is repeated until the second guard bar is detected and a whole bar code is completely read. The first scanning line may be set, so that it only reads a predetermined number of bars and the rest of the bar code is read by new scanning lines starting from the last read bar. Alternatively, the bar code region is searched by preliminarily scanning the image region divided into plural rectangular sections. The bar code region is determined based on the number of brightness changes in each divided section. The first guard bar in the bar code can be easily found in this manner.

Inventors: Shigekusa; Hisashi (Okazaki, JP), Tanaka; Masami (Handa, JP), Oshima; Tadao (Nagoya, JP)

Assignee: Denso Corporation

International Classification: G06K 7/10 (20060101); G06K 7/14 (20060101); G06K 005/04 ()

Expiration Date: 12/25/2018