Display device employing current-driven type light-emitting elements and method of driving same

A display device comprising:

• a plurality of red pixels each provided with a current-driven type red-light-emitting element;
• a plurality of green pixels each provided with a current-driven type green-light-emitting element;
• a plurality of blue pixels each provided with a current-driven type blue-light-emitting element, each of said red, green and blue pixels being provided with an inverter circuit having an output terminal thereof coupled to a corresponding one of said current-driven type red-light-emitting, green-light-emitting, and blue-light-emitting elements, a switching transistor, a storage capacitance element coupled between said switching transistor and an input terminal of said inverter circuit;
• a first circuit for short-circuiting between said input and output terminals of said inverter circuit of each of said red, green and blue pixels during a first portion of one frame period at a beginning thereof;
• a second circuit for writing a video signal voltage into said storage capacitance element of a respective one of said red, green, and blue pixels by applying a scanning drive signal on a gate electrode of said switching transistor of said respective one of said red, green, and blue pixels, during a second portion of said one frame period succeeding said first portion;
• and a third circuit for supplying at least one ramp-shaped gray scale control voltage varying from a first voltage of a first level to a second voltage of a second level different from said first level to said first terminal of said storage capacitance element of a respective one of said red, green, and blue pixels during a third portion of said one frame period succeeding said second portion;
• wherein a waveform of each of said at least one ramp-shaped gray scale control voltage is determined by light emission characteristics associated with a corresponding one of said current-driven type red-light-emitting, green-light-emitting, and blue-light-emitting elements.

A display device comprising:

• a plurality of pixels, each of said pixels being provided with a current-driven type light-emitting element, a drive transistor for supplying a drive current to said current-driven type light-emitting element, a switching transistor, a storage capacitance element coupled to said switching transistor, a comparator with an output terminal thereof coupled to a gate electrode of said drive transistor, a first input terminal of said comparator supplied with a voltage stored in said storage capacitance element, and a second input terminal of said comparator supplied with a gray scale control voltage;
• a first circuit for writing a video signal voltage into said storage capacitance element of a respective one of said plurality of pixels during a first portion of one frame period at a beginning thereof by applying a scanning drive signal on a gate electrode of said switching transistor of said respective one of said plurality of pixels;
• and a second circuit for supplying, as said gray scale control voltage, a first voltage of a first level for turning off said drive transistor in said respective one of said plurality of pixels during said first portion of said one frame period, then at least one ramp voltage varying from said first voltage of said first level to a second voltage of a second level different from said first level during a second portion of said one frame period succeeding said first portion.