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When an electrical characteristic of the TFT varies, display unevenness such as brightness unevenness or gradation unevenness is occurred in a display image. According to the present invention, a display device in which variation of an electrical characteristic of a TFT is reduced, and display uneve

When an electrical characteristic of the TFT varies, display unevenness such as brightness unevenness or gradation unevenness is occurred in a display image. According to the present invention, a display device in which variation of an electrical characteristic of a TFT is reduced, and display unevenness is reduced is provided. To obtain the display device, the fluctuation ratio of ON current value in a saturation region of adjacent TFTs is set to be equal to or less than ±12% in a TFT array substrate in which a plurality of TFTs are arranged.

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What is claimed is: 1. A display device comprising plural pixels, at least one of the plural pixels comprising: a light emitting element; a first thin film transistor, a second thin film transistor, and a third thin film transistor; a first gate signal line, and a second gate signal line, a source

What is claimed is: 1. A display device comprising plural pixels, at least one of the plural pixels comprising: a light emitting element; a first thin film transistor, a second thin film transistor, and a third thin film transistor; a first gate signal line, and a second gate signal line, a source signal line, and a current supply line, wherein a gate of the first thin film transistor is electrically connected to the first gate signal line and a second terminal of the third thin film transistor, wherein a first terminal of the first thin film transistor is electrically connected to the source signal line, wherein a second terminal of the first thin film transistor is electrically connected to a gate of the second thin film transistor and a first terminal of the third thin film transistor, wherein a first terminal of the second thin film transistor is electrically connected to the current supply line, wherein a second terminal of the second thin film transistor is electrically connected to the light emitting element, wherein a second terminal of the third thin film transistor is electrically connected to the first gate signal line, wherein a gate of the third thin film transistor is electrically connected to the second gate signal line, and wherein a channel of the second thin film transistor is folded and orients in a plurality of directions. 2. A display device according to claim 1, wherein a channel length of the second thin film transistor is at least 5 times as long as a gate width of the second thin film transistor. 3. A display device according to claim 1, wherein the second thin film transistor comprises a semiconductor layer which is formed by irradiating with a pulsed laser beam. 4. An electronic device having the display device according to claim 1, wherein the electronic device is selected from the group consisting of a display device, a video camera, a notebook computer, a personal digital assistant, a digital still camera, and a mobile telephone. 5. The display device according to claim 1, wherein the first thin film transistor is an N-channel thin film transistor, wherein the second thin film transistor is a P-channel thin film transistor, and wherein the third thin film transistor is an N-channel thin film transistor. 6. A display device comprising plural pixels, at least one of the plural pixels comprising; a light emitting element a first thin film transistor, a second thin film transistor, and a third thin film transistor; a first gate signal line, and a second gate signal line, a source signal line, and a current supply line, wherein a gate of the first thin film transistor is electrically connected to the first gate signal line and a second terminal of the third thin film transistor, wherein a first terminal of the first thin film transistor is electrically connected to the source signal line, wherein a second terminal of the first thin film transistor is electrically connected to a gate of the second thin film transistor and a first terminal of the third thin film transistor, wherein a first terminal of the second thin film transistor is electrically connected to the current supply line, wherein a second terminal of the second thin film transistor is electrically connected to the light emitting element, wherein a second terminal of the third thin film transistor is electrically connected to the first gate signal line, wherein a gate of the third thin film transistor is electrically connected to the second gate signal line, and wherein a channel of the second thin film transistor is folded and orients in a plurality of directions, and wherein brightness of the light emitting element is arranged to be fluctuated depending on an ON current value in a saturation region of a drain-voltage-drain current characteristic of the second thin film transistor. 7. A display device according to claim 6, wherein a channel length of the second thin film transistor is at least 5 times as long as a gate width of the second thin film transistor. 8. A display device according to claim 6, wherein the second thin film transistor comprises a semiconductor layer which is formed by irradiating with a pulsed laser beam. 9. An electronic device having the display device according to claim 6, wherein the electronic device is selected from the group consisting of a display device, a video camera, a notebook computer, a personal digital assistant, a digital still camera, and a mobile telephone. 10. The display device according to claim 6, wherein the first thin film transistor is an N-channel thin film transistor, wherein the second thin film transistor is a P-channel thin film transistor, and wherein the third thin film transistor is an N-channel thin film transistor. 11. A display device comprising plural pixels including: a driving thin film transistor, a switching thin film transistor, an erasing thin film transistor, a light emitting element which is connected to a second terminal of the driving thin film transistor; and a first gate signal line, and a second gate signal line, a source signal line, and a current supply line, wherein a gate of the switching thin film transistor is electrically connected to the first gate signal line and a second terminal of the erasing thin film transistor, wherein a first terminal of the switching thin film transistor is electrically connected to the source signal line, wherein a second terminal of the switching thin film transistor is electrically connected to a gate of the driving thin film transistor and a first terminal of the erasing thin film transistor, wherein a first terminal of the driving thin film transistor is electrically connected to the current supply line, wherein a second terminal of the erasing thin film transistor is electrically connected to the first gate signal line, wherein a gate of the erasing thin film transistor is electrically connected to the second gate signal line, and wherein a channel of the driving thin film transistor is folded and orients in a plurality of directions. 12. A display device according to claim 11, wherein a channel length of the driving thin film transistor is at least 5 times as long as a gate width of the driving thin film transistor. 13. A display device according to claim 11, wherein the driving thin film transistor comprises a semiconductor layer formed by irradiating with a pulsed laser beam. 14. An electronic device having the display device according to claim 11, wherein the electronic device is selected from the group consisting of a display device, a video camera, a notebook computer, a personal digital assistant, a digital still camera, and a cellular phone. 15. The display device according to claim 11, wherein the switching thin film transistor is an N-channel thin film transistor, wherein the driving thin film transistor is a P-channel thin film transistor, and wherein the erasing thin film transistor is an N-channel thin film transistor. 16. A cellular phone comprising a main body, a display portion, a voice output portion, an operation switch, and an antenna, wherein the display portion comprises plural pixels, wherein at least one of the plural pixels includes a light emitting element, a first thin film transistor, a second thin film transistor, a third thin film transistor, a first gate signal line, a second gate signal line, a source signal line, and a current supply line, wherein a gate of the first thin film transistor is electrically connected to the first gate signal line and a second terminal of the third thin film transistor, wherein a first terminal of the first thin film transistor is electrically connected to the source signal line, wherein a second terminal of the first thin film transistor is electrically connected to a gate of the second thin film transistor and a first terminal of the third thin film transistor, wherein a first terminal of the second thin film transistor is electrically connected to the current supply line, wherein a second terminal of the second thin film transistor is electrically connected to the light emitting element, wherein a second terminal of the third thin film transistor is electrically connected to the first gate signal line, wherein a gate of the third thin film transistor is electrically connected to the second gate signal line, and wherein a channel of the second thin film transistor is folded and orients in a plurality of directions. 17. The cellular phone according to claim 16, wherein the first thin film transistor is an N-channel thin film transistor, wherein the second thin film transistor is a P-channel thin film transistor, and wherein the third thin film transistor is an N-channel thin film transistor. 18. A notebook computer comprising a main body, a case, a display portion, and a keyboard, wherein the display portion comprises plural pixels, wherein at least one of the plural pixels includes a light emitting element, a first thin film transistor, a second thin film transistor, a third thin film transistor, a first gate signal line, a second gate signal line, a source signal line, and a current supply line, wherein a gate of the first thin film transistor is electrically connected to the first gate signal line and a second terminal of the third thin film transistor, wherein a first terminal of the first thin film transistor is electrically connected to the source signal line, wherein a second terminal of the first thin film transistor is electrically connected to a gate of the second thin film transistor and a first terminal of the third thin film transistor, wherein a first terminal of the second thin film transistor is electrically connected to the current supply line, wherein a second terminal of the second thin film transistor is electrically connected to the light emitting element, wherein a second terminal of the third thin film transistor is electrically connected to the first gate signal line, wherein a gate of the third thin film transistor is electrically connected to the second gate signal line, and wherein a channel of the second thin film transistor is folded and orients in a plurality of directions. 19. The notebook computer according to claim 18, wherein the first thin film transistor is an N-channel thin film transistor, wherein the second thin film transistor is a P-channel thin film transistor, and wherein the third thin film transistor is an N-channel thin film transistor. 20. A semiconductor device comprising plural pixels, at least one of the plural pixels comprising: a light emitting element; a first thin film transistor, a second thin film transistor, and a third thin film transistor; a first gate signal line, and a second gate signal line, a source signal line, and a current supply line, wherein a gate of the first thin film transistor is electrically connected to the first gate signal line and a second terminal of the third thin film transistor, wherein a first terminal of the first thin film transistor is electrically connected to the source signal line, wherein a second terminal of the first thin film transistor is electrically connected to a gate of the second thin film transistor and a first terminal of the third thin film transistor, wherein a first terminal of the second thin film transistor is electrically connected to the current supply line, wherein a second terminal of the second thin film transistor is electrically connected to the light emitting element, wherein a second terminal of the third thin film transistor is electrically connected to the first gate signal line, wherein a gate of the third thin film transistor is electrically connected to the second gate signal line, and wherein a channel of the second thin film transistor is folded and orients in a plurality of directions. 21. An electronic device having the semiconductor device according to claim 20, wherein said electronic device is selected from the group consisting of a display device, a video camera, a notebook computer, a personal digital assistant, a digital still camera, and a cellular phone. 22. The semiconductor device according to claim 20, wherein the first thin film transistor is an N-channel thin film transistor, wherein the second thin film transistor is a P-channel thin film transistor, and wherein the third thin film transistor is an N-channel thin film transistor.