| 摘要 |
A rotatable drum is arranged around a surface lying generally parallel to the axis of rotation, a plurality of bar code patterns, the individual bars making up each pattern extending normal to the rotational axis. A light beam in a plane is projected onto the surface, the plane lying generally parallel to the rotational axis such that light strikes the surface. A light beam also in a plane is reflected from the surface, the beam having relatively light and relatively dark regions corresponding to the particular bar code patterns upon which the projected beam is imaged. The reflected beam is passed through a cylindrical lens which fans the reflected beam into a wedge shaped beam projecting onto an object in the path of the beam successive bar patterns as the drum rotates.
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