Patent ID: 8314757

Claim:
An apparatus for driving light emitting elements, comprising: a constant-current driver arranged for each of one or more arrays of light emitting elements, connected to a first end of the array of light emitting elements, and including a constant-current drive element and a current regulator, the current regulator turning on/off the constant-current drive element with a control signal to regulate a current of the constant-current drive element; a first selector configured to select one having a highest signal level from among the control signals of the constant-current drivers and output the selected control signal; a second selector configured to select a lowest one from among output voltages of the constant-current drivers and output a signal representative of the selected output voltage; a differential amplifier configured to output an amplified differential signal that is obtained by amplifying a difference between the signals outputted from the first and second selectors; and a power source circuit configured to control a voltage supplied to a second end of each of the arrays of light emitting elements according to the amplified differential signal.