JPS6474688A - Reading method for crossed square-shaped code - Google Patents

Abstract

PURPOSE:To accurately read code information despite the tilt of the arraying direction of crossed square-shaped codes and the advancing direction of a scan line, by arraying the codes in the (x) direction together with the reference lines of prescribed size set before and after the code in the (y) direction and obtaining position information on the codes based on the position information on the reference lines. CONSTITUTION:A first reference line 3 is scanned and another line 3 is set after the continuous black picture elements of about 9mm. Thus the coordinates of points 3a and 3b are obtained. Then an area separated from the upper end of a mesh of a quadruple square-shaped ode 1 by 0.25-1.5mm is scanned on the scan lines preceding said points by 2.5mm and 4.5mm respectively. Then the black mesh is decided when the black picture elements equivalent to 0.8mm are continuous. In case both (x) and (y) directions are tilted, the position of the scan line for black/white decision of meshes satisfactorily responds to the position of the mesh as long as the degree of said tilt is kept within the tilt of the diagonal line of the line 3. Thus it is possible to accurately decided the position of the code 1 and the code information can be correctly read.