Patent ID: 8384629

Claim:
A pixel drive apparatus for driving pixels each having a light emitting device and a drive transistor whose current path has a first end connected to the light emitting device, the apparatus comprising: a power supply configured to be connectable to a second end of the current path of the drive transistor and to output a supply voltage; an offset voltage generating circuit that generates an offset voltage; a voltage controlling circuit that generates an output voltage which is a predetermined gradation voltage added with the offset voltage; and a current comparison circuit that compares a current value of a reference current corresponding to the gradation voltage with a current value of current flowing in the current path of the drive transistor when the supply voltage is applied to the second end of the current path of the drive transistor and a voltage based on the output voltage is applied to a control terminal of the drive transistor; wherein the offset voltage generating circuit sets a voltage value of the offset voltage through binary search based on a voltage value of an initial voltage, and acquires a specific offset voltage corresponding to a variation of a characteristic of the drive transistor based on a result of comparison performed by the current comparison circuit according to the offset voltage; and wherein the offset voltage generating circuit: generates the offset voltage based on a digital value of a predetermined number of bits; generates, as the digital value, a first value set through the binary search, and a second value obtained by increasing or decreasing one bit from the first value; repetitively performs re-setting of the voltage value of the offset voltage to a value changed through the binary search, and the comparison in the current comparison circuit according to the set offset voltage, until the current value of the reference current is judged to lie in a range of current values of two currents flowing in the current path of the drive transistor according to two offset voltages corresponding to the first value and the second value; and acquires the offset voltage corresponding to the first value as the specific offset voltage when the current value of the reference current is judged to lie in the range.