	US 7,586,505 B2
	Light emitting device and electronic apparatus using the same
Shunpei Yamazaki, Tokyo (Japan); and Jun Koyama, Kanagawa (Japan)
Assigned to Semiconductor Energy Laboratory Co., Ltd., Kanagawa-Ken (Japan)
Filed on Dec. 22, 2005, as Appl. No. 11/313,854.
Application 11/313854 is a division of application No. 10/259283, filed on Sep. 27, 2002, granted, now 7,158,157.
Claims priority of application No. 2001-300539 (JP), filed on Sep. 28, 2001.
Prior Publication US 2006/0103684 A1, May 18, 2006
This patent is subject to a terminal disclaimer.
Int. Cl. G09G 5/10 (2006.01)

U.S. Cl. 345—691 [345/690]

12 Claims

1. A light emitting device comprising:

a plurality of light emitting elements;

a voltage source for supplying voltages to the plurality of light emitting elements;

means for calculating an accumulation of light emission periods of each of the plurality of light emitting elements based on video signals for controlling the light emission periods of the plurality of light emitting elements;

means for storing the calculated accumulation of the light emission periods of each of the plurality of light emitting elements;

means for storing data on a time-varying luminance characteristic of the plurality of light emitting elements;

means for determining an amount of luminance variation compared to an initial luminance of each of the plurality of light emitting elements based on the data on the time-varying luminance characteristic of the plurality of light emitting elements and the calculated accumulation of the light emission periods of the plurality of light emitting elements;

means for correcting the voltages supplied from the voltage source to the plurality of light emitting elements to return a luminance of one of the plurality of light emitting elements to the initial luminance; and

means for correcting the video signals in a manner to compensate for a difference between the amount of luminance variation compared to the initial luminance of the one of the plurality of light emitting elements and an amount of luminance variation compared to the initial luminance of each of the other light emitting elements than the one of the plurality of light emitting elements, thereby correcting a gradation level of each of the other light emitting elements than the one of the plurality of light emitting elements.