Patent Number: 7,042,427

Title: Light emitting device

Abstract: A light emitting device with a simple and easy structure without waste is provided, in which a change of luminance of an OLED is suppressed and a desired color display can be stably performed even if an organic light emitting layer is somewhat deteriorated or an environmental temperature is varied. A driving current of the OLED of a pixel portion is measured, and a value of the voltage supplied to the pixel portion from a variable power supply is corrected such that the measured driving current has a reference value. When the driving current of the OLED is measured, a monitor video signal of a different system from that of a video signal for displaying an image is used to display a monitor image on the pixel portion. With the above-described structure, a reduction of the luminance accompanied with the deterioration of the organic light emitting layer can be suppressed. As a result, a clear image can be displayed.

Inventors: Inukai; Kazutaka (Kanagawa, JP)

Assignee: Semiconductor Energy Laboratory Co., Ltd.

International Classification: G09G 3/30 (20060101)

Expiration Date: 5/09/02018