Patent ID: 8581808

Claim:
A pixel driving circuit of an electro-luminescent display device, including an OLED (organic light emitting diode) panel that displays an image, comprising: a drive current control unit that outputs a current control signal corresponding to a level of a detected drive current by detecting an amount of a current supplied to the OLED panel; and a drive current supply unit that supplies the current to the OLED panel through a power supply terminal according to the current control signal, wherein the current control signal is a pulse width modulation signal, wherein the drive current control unit comprises: a comparator that compares the current control signal with a power supply voltage and outputs a bias voltage; a transistor that receives the power supply voltage and that supplies a drive current to the OLED panel corresponding to the bias voltage; a signal generating unit that generates a pulse width modulation signal that varies according to a difference between a reference value and the detected drive current; a control signal generating unit that receives the pulse width modulation signal from the signal generating unit and produces a control signal on the basis of the pulse width modulation signal; and a current control unit that receives the control signal and produces the current control signal.