Low current drive of light emitting device

摘要

Control circuitry for an array of light emitting devices (23,27) includes a first column line (20) connected to each light emitting device (23,27) in a column of light emitting devices (23,27). First column circuitry includes a first current source (15) and a second current source (20). The first current source (15) is connected to the first column line (20). The second current source (20) is connected to the first column line (20). When a first light emitting device (23,27) from the column of light emitting devices (23,27) is to be turned on, the first current source (15) is turned on until a voltage on the first column line (20) is equal to a predetermined voltage. Then the first current source (15) is turned off and the second current source (20) supplies current sufficient to cause the first light emitting device (23,27) to emit light to a first brightness level. <IMAGE>