Organic light-emitting diode (OLED) pre-charge circuit for use in a common anode large-screen display

摘要

The present invention is a pre-charge circuit integrated within the drive circuitry of a common anode, passive matrix, large-screen organic light-emitting diode (OLED) display device for overcoming the inherent capacitance characteristics C_OLED of the OLED devices therein. More specifically, a first pre-charge circuit of the present invention includes a MOSFET device integrated within the normal drive circuitry for applying a pre-charge voltage to the cathode of a given OLED device just prior to the desired “on” time, thereby overcoming C_OLED rapidly. A second pre-charge circuit of the present invention integrates within the normal drive circuitry a method of connecting the anode of a given OLED device to a positive voltage while concurrently connecting the cathode to ground just prior to the desired on time, thereby overcoming C_OLED rapidly. A third pre-charge circuit of the present invention includes an additional current source for supplying current over and above the normal operating current, which is activated just prior to the desired on time, thereby overcoming C_OLED rapidly. Finally, in a fourth pre-charge circuit of the present invention, a single current source is used that supplies a high current value just prior to the desired on time. Once the capacitor is charged, the output of this current source rapidly drops to the normal constant operating current.