PURPOSE: To eliminate the need of the memory of a look-up table system for obtaining mixed color components and to suppress the increase of memory capacity even when the increase of the bits of data or the like is advanced for high picture quality.

CONSTITUTION: So as to decide the respective color components of a mixed color C' (R', G' and B') from a certain foundamental color C (R, G and B), current values made to flow to the light emitting diode arrays 2R, 2G and 2B of the respective colors of red, green and blue are decided and the light emitting diode arrays of the three colors are simultaneously made to emit light by the respective current values. For the respective current values, resistor arrays 5R, 6G and 7B for the respective colors and a multiplexer MPX are provided and respective resistor groups 5, 6 and 7 are selected in the multiplexer by selection signals from a control part 4.