Patent ID: 7129917

Claim:
A driving method of a light-emitting device comprising: at least one frame period including at least one line period, the line period comprising: selecting a gate signal line connected to switching TFTs by inputting a selection signal from a gate signal line driving circuit, inputting a video signal to each of source signal lines from a source signal line driving circuit, and inputting the video signal inputted to each of the source signal lines to a gate electrode of each of current controlling TFTs through each of the switching TFTs, wherein an emission brightness of each of EL elements is controlled by the video signal inputted to the gate electrode of each of the current controlling TFTs, and wherein a drain current of each of the current controlling TFTs when the emission brightness of the EL element becomes maximum is Id, a mobility is μ, a gate capacitance per unit area is C 0 , a maximum gate voltage is Vgs (max) , a channel width is W, a channel length is L, an average value of a threshold voltage is Vth, a deviation from the average value of the threshold voltage is ΔVth, and a difference in the emission brightness of each of the EL elements is within a range of ±n %, A = 2 ⁢ ⁢ I ⁢ ⁢ d μ * C 0 A ( Vgs ( max ) - Vth ) 2 ≦ W L ≦ ( 1 + n 100 - 1 ) 2 * A Δ ⁢ ⁢ Vth 2 .