A display device able to hold a drain potential of an output transistor
functioning as a constant current source constant even in a sampling
period of another circuit, able to suppress a change due to leakage of a
gate potential of the output transistor, able to obtain a uniform current
source free from variation in current value of an output stage, and able
to display a high quality image without occurrence of uneven luminance
toward a scanning end part, wherein for example a current sample and hold
circuit finishing a sampling and holding operation during a period where
the sampling and holding operation of its own stage is ended and another
stage is performing a sampling and holding operation is configured so as
to carry a constant current corresponding to a sampled current by a thin
film transistor through a node by operating a leakage elimination
circuit.