Computer graphics processing and selective visual display system – Display driving control circuitry – Display power source
Reexamination Certificate
2002-10-30
2008-09-30
Lefkowitz, Sumati (Department: 2629)
Computer graphics processing and selective visual display system
Display driving control circuitry
Display power source
Reexamination Certificate
active
07429985
ABSTRACT:
Brightness irregularities that develop in a light emitting device due to is persion among pixels in the threshold values of TFTs used for supplying electric current to light emitting devices become obstacles to improved image quality of the light emitting device. As an image signal input to a pixel from a source signal line, a desired electric potential is applied to a gate electrode of a TFT for supplying electric current to an EL device, through a TFT having its gate and drain connected to each other. A voltage equal to the TFT threshold value is produced between the source and the drain of the TFT105. An electric potential in which the image signal is offset by the amount of the threshold value is therefore applied to the gate electrode of the TFT. Further, TFTs are disposed in close proximity to each other within the pixel, so that dispersions in the TFT characteristics do not easily develop. A desired drain current can thus be supplied to the EL device even if there is dispersion in the threshold values of the TFTs among pixels, because this is offset by the threshold value of the TFT.
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Kimura Hajime
Tanada Yoshifumi
Boddie William L
Fish & Richardson P.C.
Lefkowitz Sumati
Semiconductor Energy Laboratory Co,. Ltd.
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