| 摘要 |
PROBLEM TO BE SOLVED: To surely read a bar code by making a focal distance match with distance to the bar code face whether the scanning direction of a laser beam is on the side of a parallel face or the side of a vertical face to a joint face. SOLUTION: A laser beam from a semiconductor laser 81 is converted into scanning light for deflection-scanning by galvano-mirrors 86 and 87 through a variable focal point optical system 84 to scan a bar code face added to a product on a belt conveyer. In this case, depending on whether the direction of the canning light with respect to the joint surface of the semiconductor laser is on the side of a parallel face or on the side of a vertical face compared with 45 angular degree with respect to the angle 45 deg. between a parallel face and a vertical face to the joint surface, the moving quantity of a focus lens to the distance between with the bar code face, namely the automatic adjusting characteristic of the focal point, is differentiated to control the focal distance to always match with the distance to the bar code face. |
