The ripple component superimposed on the drive power source Va applied to
the source electrode of a light emission drive transistor Tr2 is
extracted by a ripple component extraction circuit 14, and the ripple
component is supplied to one input terminal of a voltage addition circuit
15. A data voltage Vdata transmitted via a data line is input to the
other input terminal of the voltage addition circuit 15. Accordingly, in
the voltage addition circuit 15, the ripple component extracted by the
ripple component extraction circuit 14 is added to the data voltage Vdata
treating the data voltage Vdata as the base. Its output is supplied to a
scan selection transistor designated by reference character SW1 as Vgate,
and the transistor Tr1 is turned on at an addressing time so that the
Vgate is supplied to the gate of the light emission drive transistor Tr2.
Thus, the gate-to-source voltage Vgs of the light emission drive
transistor Tr2 represents an approximately constant value all the time
regardless of timing of addressing. Therefore, a problem that intensity
change occurs for each scan line so that the display quality of an image
is considerably deteriorated can be avoided.