Electronic seven segment display with checking system - uses seven double segments with parallel drive converters connected to comparator

摘要

A seven segment numerical display, suitable for liquid crystal elements, is designed to provide some indication of erroneous display conditions. Each segment (2) of the display element is composed of two elements side-by-side. Seven bit words for driving the display are generated by two BLO/7 segment code converters. Identical bit positions from each of the converters are coupled to a pair of display elementS. Inputs to the converters are provided by a 5 bit shift register, with the fifth bit being an odd parity checking bit. The system is completed by seven-two bit comparators coupled to each bit position of the converter output. A check on a individual comparator output as compared with the actual display enables the source of error to be located.