Patent ID: 7425728

Claim:
A surface light source control device comprising: a liquid crystal panel having a display area with a plurality of display pixels two-dimensionally arrayed therein; a plane light source section having a circuit board driving the panel and a plurality of diode arrays with a plurality of light emitting diodes LEDs serially arrayed thereon; a power supply circuit commonly applying a common power supply voltage to one terminal of the plurality of diode arrays; a constant current circuit connected to the other terminal of the plurality of diode arrays to hold currents respectively flowing to each of the diode arrays constant so that the currents have the same current value; a voltage selection circuit for detecting a notable array with the lowest minimum reference voltage, among reference voltages obtained after the common power supply voltage applied to the plurality of diode arrays are respectively dropped at the plurality of diode arrays, appearing thereon to select the lowest minimum reference voltage; and a power supply control loop for adjusting a voltage value of the common power supply voltage so that the reference voltage selected by the selection circuit becomes a prescribed value.