Abstract: A controller for use with a multi-segment electroluminescent display 1. Control signals C1–CN control a plurality of half H-bridges H and Hc, the terminals of the half H-bridges being connected respectively to ground and to a high voltage DC supply 9. One of said half H-bridges provides a common output Vcommon and the remaining H-bridges provide drive voltages V1–VN for the segments of the display. The H bridges are driven by an oscillator 14 so that an AC voltage is selectively applied to the segments of the display. A power supply 24 provides a predetermined amount of power per unit area of the display. This is controlled by an area summation engine 22 having a segment data input, a segment counter and a memory containing area data corresponding to the segment(s) of the display. Based on the input from the segment data input, the area(s) of the segment(s) that are to be lit are obtained from the memory and summed to provide the total area to be lit.

Abstract: A controller 2 is provided for use with a multi-segment electroluminescent display 1. Control signals C1–C5 control a plurality of half H-bridges H1–H5, 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 V1–V4 for the segments of the display. During each cycle, the controller 2 causes the drive outputs V1–V4 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.