Read head for bar codes - has several transmitters of different spectral colours to obtain good reflection of light from bar code contg. lines of several spectral colours

摘要

The read head (2) contains a pair of glass fibre optical conductors (3, 4) coupled to an optical receiver (7), and three optical transmitters (5). The three optical transmitters output light from several light sources of different spectral colours. The transmitted light outputs are directed onto the surface containing the bar code. Each line in the bar code comprising of several closely spaced lines of different spectral colours. This allows reflected signals to be generated that can be identified for different bar code backgrounds and conditions. ADVANTAGE - Allows bar codes to be read from different backgrounds.