Patent ID: 7945179

Claim:
A light-emitting device comprising: a plurality of light-emitting elements that emit light in response to driving signals, a control unit that adjusts the timings at which the driving signals are supplied to a plurality of blocks, each block being composed of two or more light-emitting elements, each light-emitting element directly connected to a driving unit, wherein the control unit generates control signals for indicating the timings at which the driving signals are supplied for every block; and a plurality of driving units that are provided for the blocks and supply the driving signals to the light-emitting elements belonging to the corresponding blocks on the basis of the control signals, wherein the light-emitting elements composing a block simultaneously emit light at a first time, and do not emit light at a second time, wherein the control unit classifies the blocks into a plurality of groups, each group supplying the driving signals at the same timing, generates the control signals to be supplied to the plurality of groups at different timings, and regroups the blocks in response to a setting signal, wherein the control unit generates a single control signal for each driving unit, and wherein the setting signal designates a printing quality, and the control unit regroups the blocks such that the number of blocks belonging to each of the groups increases as the printing quality designated by the setting signal increases, thereby reducing the number of groups.