Pixel circuit, display device, and method of driving pixel circuit

Abstract

A pixel circuit, display device, and method of driving a pixel circuit enabling source-follower output with no deterioration of luminance even with a change of the current-voltage characteristic of the light emitting element along with elapse, enabling a source-follower circuit of n-channel transistors, and able to use an n-channel transistor as an EL drive transistor while using current anode-cathode electrodes. The circuit includes a source of a TFT used as a drive transistor that is connected to an anode of a light emitting element, and a drain of the TFT is connected to a power source potential. A capacitor is connected between a gate and source of the TFT, and a source potential of the TFT is connected to a fixed potential through a TFT used as a switching transistor.

1 . A display device comprising:
 a plurality of pixel circuits for driving electro-optic elements;   scanner circuitry configured to drive the pixel circuits;
 a first control line and a second control line, each connected to the scanner circuitry; and 
 first and second reference potential lines, 
 wherein at least one of the plurality of pixel circuits includes: 
   a data line through which a data signal in accordance with luminance information is supplied,   an n-type drive transistor including a first terminal, a second terminal and a control terminal, the drive transistor being configured to form a current supply line from the said first reference potential line to said second reference potential line, via the first terminal, the second terminal and one of the electro-optic elements,   a pixel capacitor connected between said control terminal and said second terminal, wherein the n-type drive transistor is configured to control a current flowing through said current supply line in accordance with a voltage stored in the pixel capacitor,   an n-type first thin film transistor (TFT) connected between said data line and the control terminal and controlled by said first control line,   an n-type second TFT connected to the second terminal so as to set a potential of the second terminal to a predetermined potential while said electro-optic element is not emitting light, the second TFT being controlled by at least the second control line, the second control line being connected only to the second TFT within said at least one of the pixel circuits, and the second TFT being configured to be, within one scanning period, (i) turned on before the first TFT is turned on, and (ii) turned off after the first TFT is turned on, and   the second terminal is connected to an anode electrode of said one of the electro-optic elements,   wherein the n-type first TFT, the n-type second TFT and the n-type third TFT are formed by an amorphous silicon process.