A novel driving method for conducting gradation display is provided. Also, a
signal
line driver circuit is provided which includes a current source circuit having
a small area. Further, miniaturization and reduction in size of a frame of a light-emitting
device can be attained. A gate selection period is divided into plural periods,
and a (writing) operation of writing a signal to a pixel having a transistor connected
with a scanning line that is selected and a (reading) operation of reading a signal
current into a current source circuit connected with a signal line connected with
a scanning line that is not selected are performed simultaneously in each of the
divided periods in the gate selection period. Therefore, the signal line driver
circuit that includes a current source circuit having a small area is provided.
Consequently, the miniaturization and reduction in size of the frame of the light-emitting
device can be attained.
