Control of electroluminescent displays

摘要

A controller 2 is provided for use with a multi-segment electroluminescent display 1 . Control signals C 1 -C 5 control a plurality of half H-bridges H 1 -H 5 , the terminals of the half H-bridges being connected respectively to ground 10 and to a high voltage DC supply 9 so that the half H-bridges each provide an AC voltage. One of said half H-bridges provides a common output Vcommon and the remaining H-bridges provide drive voltages V 1 -V 4 for the segments of the display. During each cycle, the controller 2 causes the drive outputs V 1 -V 4 to either be in phase or in anti-phase with the common output Vcommon. This selectively turns the segments on and off at a rate much higher than the human eye can perceive. The brightness of the segments is controlled by varying the proportion of the time that each segment is illuminated.