Method and apparatus for non-contact reading of a relief pattern

Abstract

An improved non-contact apparatus and method for reading a surface that has information encoded in a relief pattern thereon, includes an optical transmitter for projecting a line of light onto the relief pattern at a first angle to a normal of the surface; an optical receiver that views the projected line of light at a second angle to the normal of the surface and produces signal data that is representative of an image of the reflection thereon. The image viewed by the receiver has parallactic displacements of the line of illumination that occur at transitions between raised and recessed portions of the relief pattern. The signal data is culled such that only those pixels surrounding the line of light are selected. The culled signal data is then decoded into electrical signals which represent decoded information contained in the relief pattern. The optical receiver can be realized as a plurality of light sensors arranged in a linear, or a two dimensional array, together with suitable focusing optics. The optical transmitter can produce either a fan beam of light or sweep a spot of light across the surface. The optical transmitter, optical receiver, the culling, circuit and the decoding circuit contained within either a portable hand-held unit or a fixed mount unit.