METHOD AND APPARATUS FOR NON-CONTACT READING OF A RELIEF PATTERN

摘要

There is disclosed a non-contact apparatus and method for reading a surface (8) that has information encoded in a relief pattern thereon. The apparatus comprises an optical transmitted (2) for projecting a line of light (6) onto the relief pattern at a first angle to a normal of the surface; an optical receiver (3) that views the projected line of light at a second angle to the normal of the surface and produces a signal that is representative of an image of the reflection thereon. The image viewed by the receiver has parallactic displacements (20) of the line of illumination that occur at transitions between raised and recessed portions of the relief pattern (28). The displacements (20) are detected by a pattern detector (4) which is coupled to the optical receiver (3) and submitted to a decoder (5). The optical receiver (3) can be realized as a plurality of light sensors arranged in a linear, or a two dimensional array (22, 26) together with suitable focusing optics (21, 24). The optical transmitter (2) can produce either a fan beam of light or sweep a spot of light across the surface.