Patent ID: 9269725
Filing Date: 2016-02-23
CPC Classification: G02F,G09G,H01L

Claim Text:
1. A display device provided with a display panel comprising: a pixel portion comprising a pixel, wherein the pixel comprises a liquid crystal display element and a first transistor including an oxide semiconductor layer; a driver circuit portion configured to drive the pixel portion and display an image on a screen; and a switching element comprising a second transistor including the oxide semiconductor layer, wherein the oxide semiconductor layer comprises a crystal, wherein a c-axis of the crystal is aligned in a direction perpendicular to a surface of the oxide semiconductor layer, wherein the first transistor and the second transistor are connected to each other with the liquid crystal display element, wherein the driver circuit portion has a function to write a first image signal and a second image signal to the pixel successively so as to display an image on the screen, and a function to stop a writing operation of the second image signal and turn the first transistor off so as to maintain one image written to the screen when a difference is not detected between the first image signal and the second image signal, and wherein an off current of each of the first transistor and the second transistor is lower than 10 zA/μ m at room temperature and lower than 100 zA μ m at 85 ° C.