Monitoring of LED type displays to ensure they are operating correctly, e.g. for signal displays used with railway switching and control, by monitoring the current drawn by individual display units and the whole unit

摘要

An electronically protected power supply to a circuit assemblies (21-25) and sequential comparators (31-35) in which a supply current (IR) is monitored to determine if it falls below or above threshold values. An overall comparator (4) is provided to determine if the total current exceeds or falls below reference thresholds. Dependent on the individual and group comparisons corresponding result values ER and EG are generated. According to their valves power supply can be reduced or increased. The invention also relates to a corresponding display for display of time-varying information made up of an array of LEDs.