A plurality of pairs of switch parts and current source circuits are
disposed in each pixel. Switching of each of a plurality of the switch
parts is controlled by a digital video signal. When the switch part is
turned on, by a current supplied from the current source circuit making a
pair with the switch part, the light emitting element emits light. A
current which is supplied from one current source circuit to the light
emitting element is constant. A value of a current flowing through the
light emitting element is comparable to a value of added currents which
are supplied to the light emitting element from respective all current
source circuits making pairs with the switch parts which are in the
conductive states.