Method and apparatus for reading an optically two-dimensional code.

摘要

A two-dimensional code 1 consists of three positioning symbols 2, a data region 3, timing cells 4 and an apex detecting cell 5. The shape of the whole code 1 is a square having the same number of vertical and lateral cells. A scanning line passing through the center of each positioning symbols 2 always gives a constant frequency component ratio dark : light : dark : light : dark = 1 : 1 : 3 : 1 : 1, irrespective of the scanning direction. For this reason, even if a rotational angle of the two-dimensional code is not certain, the specific frequency component ratio of each positioning symbol 2 can be easily detected by executing only one scanning operation in a predetermined direction. Hence, the coordinates of the center of each positioning symbols 2 can be easily found. Thus, the position of the two-dimensional code 1 is quickly identified. <IMAGE>