Abstract: There are disclosed a system and method for decoding data read from a plurality of different types of bar code labels which includes circuit means for detecting the occurrence of two equal continuous characters in the data generated by an optical scanner in reading a bar code label and a filter for each of the different bar code labels receiving simultaneously the two equal characters for decoding the character data and inserting locating bits in the data delimiting a valid character in the data.

Abstract: The useful life of a laser, such as a laser diode, is extended by causing the laser to operate only intermittently when continuous operation is not required. When such a laser diode is used in a scanner for scanning coded symbols, such as bar codes, in merchandise check-out operations, continuous operation is required only when a coded symbol is present in a target area. A sensing device is provided for sensing the transitions in light reflected back from the target area, and a counter is provided for counting the number of such transitions. Since a much larger number of transitions are sensed and counted when a coded symbol is being read than when no such symbol is present in the target area, this difference in number of transitions is used to distinguish between the two conditions and to cause the laser diode to be turned on for continuous operation only when a coded symbol is present in the target area to be read.