an increase of a value of the gradation data if the gradation data is u201c 63 u201d decimal number the h level duty ratio of the pwm signal is supposed to become 100 the switching circuit 82 is a circuit for changing a current from the current mirror 80 according to the h level duty ratio of the pwm signal and outputting it as the driving current idr 0 in this embodiment if the h level duty ratio of the pwm signal is zero a current value of the driving current idr 0 becomes the minimum value that is zero and the current value of the driving current idr 0 is supposed to be increased according to the increase of the h level duty ratio of the pwm signal also if the h level duty ratio of the pwm signal becomes 100 the driving current idr 0 becomes the maximum value that is imax the driving current generation circuits 61 to 67 generate similarly to the driving current generation circuit 60 the driving currents idr 1 to idr 7 according to the gradation data stored in the storage region of the gradation data storage unit 51 corresponding to each of the index data u201c 1 u201d to u201c 7 u201d decimal number and the reference current iref the selector control circuit 70 stores the index data sequentially outputted from the memory controller 36 in the order of output if one row of index data in the index data storage unit 50 that is 17 pieces of the.