Liquid crystal display device
The liquid crystal display device includes a pixel portion including first and second regions and light sources. The first and second regions each include a liquid crystal element whose transmissivity is controlled in accordance with a voltage of an image signal and a transistor for controlling holding of the voltage, whose off-state current is extremely low. The light sources perform first and second drivings: lights whose hues are different from each other are sequentially supplied to the first region in a first rotating order and the lights are sequentially supplied to the second region in a second rotating order which is different from the first rotating order in the first driving; and a light having a single hue is supplied consecutively to one or both of the first and second regions in the second driving. The period for holding the voltage is different between the first and second drivings.
1. A liquid crystal display device comprising:
a pixel portion including a first region including a first pixel and a second pixel and a second region including a third pixel and a fourth pixel, wherein the second pixel is located closer to the second region than the first pixel and the third pixel is located closer to the first region than the fourth pixel; and
a plurality of light sources including first light sources emitting a first hue and second light sources emitting a second hue,
wherein each of the first pixel, the second pixel, the third pixel, and the fourth pixel includes a liquid crystal element whose transmissivity is controlled in accordance with a voltage of an image signal and a transistor for controlling holding of the voltage,
wherein a channel formation region of the transistor contains an oxide semiconductor film whose crystal is c-axis-aliqned in a direction substantially perpendicular to a surface of the oxide semiconductor film,
wherein the plurality of light sources are configured to perform a first driving and a second driving,
wherein after a first image signal is written to the first pixel, a first light with the first hue is supplied to the first pixel in the first driving,
wherein after a second image signal is written to the third pixel, a second light with the second hue is supplied to the third pixel in the first driving,
wherein after a third image signal is written to the second pixel while the first light with the first hue is supplied to the first pixel and the second light with the second hue is supplied to the third pixel, the first light with the first hue is supplied to the second pixel in the first driving,
wherein after a fourth image signal is written to the fourth pixel while the first light with the first hue is supplied to the first pixel and the second light with the second hue is supplied to the third pixel, the second light with the second hue is supplied to the fourth pixel in the first driving,
wherein a light having a single hue is supplied consecutively to one or both of the first region and the second region in the second driving,
wherein a period for holding the voltage is different between the first driving and the second driving, and
wherein an interval between writings of image signals is 1 minute or more in the second driving.
2. The liquid crystal display device according to claim 1 , wherein the oxide semiconductor is an In—Ga—Zn—O-base oxide semiconductor.
3. The liquid crystal display device according to claim 1 , wherein a hydrogen concentration of the channel formation region is less than or equal to 5×10 19 /cm 3 .
4. The liquid crystal display device according to claim 1 , wherein an off-state current density of the transistor is less than or equal to 100 yA/μm.
5. A liquid crystal display device comprising:
a pixel portion including a first region including a first pixel and a second pixel and a second region including a third pixel and a fourth pixel, wherein the second pixel is located closer to the second region than the first pixel and the third pixel is located closer to the first region than the fourth pixel; and
a plurality of light sources including first light sources emitting a first hue and second light sources emitting a second hue,
wherein each of the first pixel, the second pixel, the third pixel, and the fourth pixel includes a liquid crystal element whose transmissivity is controlled in accordance with a voltage of an image signal and a transistor for controlling holding of the voltage,
wherein a channel formation region of the transistor contains an oxide semiconductor film whose crystal is c-axis-aliqned in a direction substantially perpendicular to a surface of the oxide semiconductor film,
wherein the plurality of light sources are configured to perform a first driving and a second driving,
wherein after a first image signal is written to the first pixel, a first light with the first hue is supplied to the first pixel in the first driving,
wherein after a second image signal is written to the third pixel, a second light with the second hue is supplied to the third pixel in the first driving,
wherein after a third image signal is written to the second pixel while the first light with the first hue is supplied to the first pixel and the second light with the second hue is supplied to the third pixel, the first light with the first hue is supplied to the second pixel in the first driving,
wherein after a fourth image signal is written to the fourth pixel while the first light with the first hue is supplied to the first pixel and the second light with the second hue is supplied to the third pixel, the second light with the second hue is supplied to the fourth pixel in the first driving,
wherein a light having a single hue is supplied consecutively to one or both of the first region and the second region in the second driving,
wherein a period for holding the voltage is increased when a driving is switched from the first driving to the second driving, and
wherein an interval between writings of image signals is 1 minute or more in the second driving.
6. The liquid crystal display device according to claim 5 , wherein the oxide semiconductor is an In—Ga—Zn—O-base oxide semiconductor.
7. The liquid crystal display device according to claim 5 , wherein a hydrogen concentration of the channel formation region is less than or equal to 5×10 19 /cm 3 .
8. The liquid crystal display device according to claim 5 , wherein an off-state current density of the transistor is less than or equal to 100 yA/μm.
9. A liquid crystal display device comprising:
a pixel portion including a first region including a first pixel and a second pixel and a second region including a third pixel and a fourth pixel, wherein the second pixel is located closer to the second region than the first pixel and the third pixel is located closer to the first region than the fourth pixel;
a plurality of light sources including first light sources emitting a first hue and second light sources emitting a second hue; and
an input device,
wherein each of the first pixel, the second pixel, the third pixel, and the fourth pixel includes a liquid crystal element whose transmissivity is controlled in accordance with a voltage of an image signal and a transistor for controlling holding of the voltage,
wherein a channel formation region of the transistor contains an oxide semiconductor film whose crystal is c-axis-aliened in a direction substantially perpendicular to a surface of the oxide semiconductor film,
wherein the plurality of light sources are configured to perform a first driving and a second driving,
wherein after a first image signal is written to the first pixel, a first light with the first hue is supplied to the first pixel in the first driving,
wherein after a second image signal is written to the third pixel, a second light with the second hue is supplied to the third pixel in the first driving,
wherein after a third image signal is written to the second pixel while the first light with the first hue is supplied to the first pixel and the second light with the second hue is supplied to the third pixel, the first light with the first hue is supplied to the second pixel in the first driving,
wherein after a fourth image signal is written to the fourth pixel while the first light with the first hue is supplied to the first pixel and the second light with the second hue is supplied to the third pixel, the second light with the second hue is supplied to the fourth pixel in the first driving,
wherein a light having a single hue is supplied consecutively to one or both of the first region and the second region in the second driving,
wherein a driving is switched between the first driving and the second driving in accordance with a signal from the input device,
wherein a period for holding the voltage is different between the first driving and the second driving, and
wherein an interval between writings of image signals is 1 minute or more in the second driving.
10. The liquid crystal display device according to claim 9 , wherein the oxide semiconductor is an In—Ga—Zn—O-base oxide semiconductor.
11. The liquid crystal display device according to claim 9 , wherein a hydrogen concentration of the channel formation region is less than or equal to 5×10 19 /cm 3 .
12. The liquid crystal display device according to claim 9 , wherein an off-state current density of the transistor is less than or equal to 100 yA/μm.
13. A liquid crystal display device comprising:
a pixel portion including a first region including a first pixel and a second pixel and a second region including a third pixel and a fourth pixel, wherein the second pixel is located closer to the second region than the first pixel and the third pixel is located closer to the first region than the fourth pixel;
a plurality of light sources including first light sources emitting a first hue and second light sources emitting a second hue; and
an input device,
wherein each of the first pixel, the second pixel, the third pixel, and the fourth pixel includes a liquid crystal element whose transmissivity is controlled in accordance with a voltage of an image signal and a transistor for controlling holding of the voltage,
wherein a channel formation region of the transistor contains an oxide semiconductor film whose crystal is c-axis-aligned in a direction substantially perpendicular to a surface of the oxide semiconductor film,
wherein the plurality of light sources are configured to perform a first driving and a second driving,
wherein after a first image signal is written to the first pixel, a first light with the first hue is supplied to the first pixel in the first driving,
wherein after a second image signal is written to the third pixel, a second light with the second hue is supplied to the third pixel in the first driving,
wherein after a third image signal is written to the second pixel while the first light with the first hue is supplied to the first pixel and the second light with the second hue is supplied to the third pixel, the first light with the first hue is supplied to the second pixel in the first driving,
wherein after a fourth image signal is written to the fourth pixel while the first light with the first hue is supplied to the first pixel and the second light with the second hue is supplied to the third pixel, the second light with the second hue is supplied to the fourth pixel in the first driving,
wherein a light having a single hue is supplied consecutively to one or both of the first region and the second region in the second driving,
wherein a driving is switched between the first driving and the second driving in accordance with a signal from the input device,
wherein a period for holding the voltage is increased when the driving is switched from the first driving to the second driving, and
wherein an interval between writings of image signals is 1 minute or more in the second driving.
14. The liquid crystal display device according to claim 13 , wherein the oxide semiconductor is an In—Ga—Zn—O-base oxide semiconductor.
15. The liquid crystal display device according to claim 13 , wherein a hydrogen concentration of the channel formation region is less than or equal to 5×10 19 /cm 3 .
16. The liquid crystal display device according to claim 13 , wherein an off-state current density of the transistor is less than or equal to 100 yA/μm.