| 摘要 |
There is provided an EL light-emitting device with less uneven brightness. When a drain current of a plurality of current controlling TFTs is Id, a mobility is μ, a gate capacitance per unit area is Co, 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 &Dgr;Vth, and a difference in emission brightness of a plurality of EL elements is within a range of ±n %, a semiconductor display device is characterized in that A = 2  Id μ * C 0 A ( Vgs ( max ) - Vth ) 2 ≦̸ W L ≦̸ ( 1 + n 100 - 1 ) 2 * A &Dgr;   Vth 2  &Dgr;   Vth  ≦̸ ( 1 + n 100 - 1 ) * A * L / W
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