Patent ID: 6995520
Filing Date: 2006-02-07
Classification: G09G,H01L

Abstract:
1. A method of driving a light emitting device comprising: a source signal line driver circuit; a first gate signal line driver circuit; a second gate signal line driver circuit; a pixel portion; a plurality of source signal lines connected to the source signal line driver circuit; a plurality of first gate signal lines connected to the first gate signal line driver circuit; a plurality of second gate signal lines connected to the second gate signal line driver circuit; and a plurality of power source supply lines; wherein said pixel portion comprises a plurality of pixels; wherein each of said plurality of pixels comprises a switching TFT; a first EL driver TFT; a second EL driver TFT; an erasure TFT; and an EL element; wherein said first EL driver TFT and said second EL driver TFT are connected in parallel; wherein a gate electrode of said switching TFT is connected to one of said plurality of first gate signal lines; wherein one of a source region and a drain region of the switching TFT is connected to one of said plurality of source signal lines, and the other of said source region and said drain region is connected to a gate electrode of said first EL driver TFT and to a gate electrode of said second EL driver TFT; wherein a gate electrode of said erasure TFT is connected to one of said plurality of second gate signal lines; wherein one of a source region and a drain region of said erasure TFT is connected to one of said plurality of power source supply lines, and the other of said source region and said drain region is connected to said gate electrode of said first EL driver TFT and to said gate electrode of said second EL driver TFT; wherein a source region of said first EL driver TFT and a source region of said second EL driver TFT are connected to said power source supply line; wherein a drain region of said first EL driver TFT and a drain region of said second EL driver TFT are connected to said EL element; wherein n write in periods Ta wherein a digital video signal output from said source signal line driver circuit is input to a gate electrode of said first EL driver TFT and to a gate electrode of said second EL driver TFT in said write in periods Ta wherein said digital video signal input to said gate electrode of said first EL driver TFT and to said gate electrode of said second EL driver TFT is erased in said erasure periods Te wherein the write in periods Ta wherein periods which begin when said write in periods Ta wherein periods begin when said erasure periods Te wherein it is selected whether said plurality of EL elements emit light or do not emit light in said display periods Tr wherein the ratio of the lengths of said display periods Tr