Patent ID: 7106290

Claim:
A method of driving an EL display device including a plurality of pixels, each having a first TFT, a second TFT, a third TFT, and an organic EL element, the method comprising: dividing a frame period into n+m display periods with n and m being natural numbers of one or more, wherein the n+m display periods each correspond to one bit of a digital video signal among n bits of the digital video signal, a plurality of display periods, among the n+m display periods correspond to the same bit of the digital video signal, and other display periods corresponding to other bits of the digital video signal, among the n+m display periods, appear between the plurality of display periods; for each of the n+m display periods, inputting the corresponding bit of the digital video signal to a gate electrode of the second TFT by turning on the first TFT and beginning the respective display period by turning off the third TFT; and after each of the n+m display period begins completing the respective display period by turning on the third TFT; wherein the organic EL element emits light when the second TFT is turned on, and does not emit light when the second TFT is turned off, wherein the first TFT comprises a crystalline semiconductor film, a gate insulating film over the crystalline semiconductor film, first and second gate electrodes formed over the crystalline semiconductor film with the gate insulating film interposed therebetween, and first and second channel forming regions in the crystalline semiconductor film below the first and second gate electrodes, respectively, and a pair of first impurity regions in the crystalline semiconductor film between the first and second channel forming regions and a third impurity region between the pair of first impurity regions.