Title: Element substrate and light emitting device
Application Number: 200410060002 Application Date: 2004.06.18
Publication Number: 1574385 Publication Date: 2005.02.02
Approval Pub. Date: Granted Pub. Date:
International Classifi-cation: G09G3/00,H01L27/15,H01L51/30,H05B33/00
Applicant(s) Name: Semiconductor Energy Laboratory Co., Ltd. Address:
Inventor(s) Name: Fukumoto Ryota, Anazai Aya, Yamazaki Yu
Attorney & Agent: zhang xuemei liang yong
Abstract:
     No need of lowering off-current of a switching transistor, fewer luminance variations of a light emitting element between pixels due to characteristic variations of a driving transistor, and less risk of steps due to increase in the number of wirings. A video signal for light emission or non-emission of a pixel is input to a gate of a current controlling transistor operated in a linear region, which is connected in series with the driving transistor, through a switching transistor. Since a voltage Vds between a source and a drain of the current controlling transistor is small, small changes in a voltage Vgs between a gate and a source thereof do not affect a current flowing in a load. The current flowing in the light emitting element is determined by the driving transistor operated in a saturation region, and a fixed potential is input to the gate thereof during light emission.
Time: 5
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