Electro-optical device

• US 20050162356A1
• Filed: 02/16/2005
• Published: 07/28/2005
• Est. Priority Date: 10/21/1999
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Koyama, Jun, Yamazaki, Shunpei, Osada, Mai, Inukai, Kazutaka
• Granted Patent: US 7,403,179 B2
• Time in Patent Office: Days
• US Class Current: 345/76
• CPC Class Codes: G09G 2300/0417 Special arrangements specific to the use of low carrier mobility technology
• CPC Class Codes: G09G 2300/0426 Layout of electrodes and connections
• CPC Class Codes: G09G 2300/0842 forming a memory circuit, e.g. a dynamic memory with one capacitor
• CPC Class Codes: G09G 2310/0254 Control of polarity reversal in general, other than for liquid crystal displays
• CPC Class Codes: G09G 2310/0256 with the purpose of reversing the voltage across a light emitting or modulating element within a pixel
• CPC Class Codes: G09G 2320/0247 Flicker reduction other than flicker reduction circuits used for single beam cathode-ray tubes
• CPC Class Codes: G09G 2320/0266 Reduction of sub-frame artefacts
• CPC Class Codes: G09G 3/2022 using sub-frames
• CPC Class Codes: G09G 3/30 using electroluminescent panels
• CPC Class Codes: G09G 3/3258 with pixel circuitry controlling the voltage across the light-emitting element
• CPC Class Codes: H01L 27/1214 comprising a plurality of TFTs formed on a non-semiconducting substrate, e.g. driving circuits for AMLCDs
• CPC Class Codes: H01L 27/156 two-dimensional arrays
• CPC Class Codes: H04N 5/44 Receiver circuitry for the reception of television signals according to analogue transmission standards H04N5/14 takes precedence

Abstract

An electro-optical device having a plurality of pixels including a plurality of EL elements, wherein the electro-optical device provides a gray scale display by controlling a period of time at which the plurality of the EL elements emit light in one frame period; the plurality of the EL elements have a first electrode and a second electrode; the first electrode is held at a constant potential; and a potential of the second electrode changes in such a manner that a polarity of an EL driving voltage, which is a difference between the potentials applied to the first and second electrodes, is inverted for each one frame period.

Claims

1. (canceled)

2. An electro-optical device comprising a plurality of pixels including a plurality of EL elements, characterized in that:

said electro-optical device provides a gray scale display by controlling a sum of lengths of sub-frame periods in which said plurality of EL elements emit light out of said plurality of sub-frame periods included in one frame period;

said plurality of EL elements comprise a first electrode and a second electrode; and

a potential of said first or said second electrode changes in such a manner that a polarity of an EL driving voltage is inverted for each one sub-frame period,

wherein said EL driving voltage is a difference between said potentials applied to said first and said second electrodes.

12. An electro-optical device according to claim 2, wherein said light emission of said plurality of EL elements is con digital data signal input to said switching TFT.

13. An electro-optical device according to claim 2, wherein said one frame period is {fraction (1/120)} s or less.

16. An electro-optical device according to claim 2, wherein said electro-optical device is one selected from the group consisting of a video camera, a digital camera, a head-mount display, a car navigation system, a personal computer, and a DVD player.

3. (canceled)

4. An electro-optical device comprising a plurality of pixels, said device including a plurality of EL elements, a plurality of EL driving TFTs for controlling light emission of said plurality of EL elements, a plurality of switching TFTs for controlling driving of said plurality of EL driving TFTs, characterized in that:

said electro-optical device provides a gray scale display by controlling a sum of lengths of sub-frame periods in which said plurality of EL elements emit light out of said plurality of sub-fame periods included in one frame period;

said plurality of EL elements comprise a first electrode and a second electrode; and

a potential of said first or said second electrode changes in such a manner that a polarity of an EL driving voltage is inverted for each one sub-frame period,

wherein said EL driving voltage is a difference between said potentials applied to said first and said second electrodes.

11. An electro-optical device according to claim 4, wherein said EL driving TFT and said switching TFT comprise an n-channel type TFT or a p-channel type TFT.

20. An electro-optical device according to claim 4, wherein said light emission of said plurality of EL elements is controlled with said digital data signal input to said switching TFT.

25. An electro-optical device according to claim 4, wherein said one frame period is {fraction (1/120)} s or less.

32. An electro-optical device according to claim 4, wherein said electro-optical device is one selected from the group consisting of a video camera, a digital camera, a head-mount display, a car navigation system, a personal computer, and a DVD player.

5. (canceled)

6. An electro-optical device comprising a plurality of pixels including a plurality of EL elements, characterized in that:

said electro-optical device provides a gray scale display by controlling a sum of lengths of sub-frame periods in which said plurality of EL elements emit light out of said plurality of sub-frame periods included in one frame period;

said plurality of EL elements comprise a first electrode and a second electrode; and

a potential of said first or said second electrode changes in such a manner that a polarity of an EL driving voltage is inverted for each one frame period ; and

adjacent pixels of said plurality of pixels share a power source supply line for supplying a voltage applied to said second electrode,

wherein said EL driving voltage is a difference between said potentials applied to said first and said second electrodes.

21. An electro-optical device according to claim 6, wherein said light emission of said plurality of EL elements is controlled with said digital data signal input to said switching TFT.

26. An electro-optical device according to claim 6, wherein said one frame period is {fraction (1/120)} s or less.

33. An electro-optical device according to claim 6, wherein said electro-optical device is one selected from the group consisting of a video camera, a digital camera, a head-mount display, a car navigation system, a personal computer, and a DVD player.

7. (canceled)

8. An electro-optical device comprising a plurality of pixels, said device including a plurality of EL elements, a plurality of EL driving TFTs for controlling light emission of said plurality of EL elements, a plurality of switching TFTs for controlling driving of said plurality of EL driving TFTs, characterized in that:

said electro-optical device provides a gray scale display by controlling a sum of lengths of sub-frame periods in which said plurality of EL elements emit light out of said plurality of sub-frame periods included in one frame period;

said plurality of EL elements comprise a first electrode and a second electrode; and

a potential of said first or said second electrode changes in such a manner that a polarity of an EL driving voltage is inverted for each one sub-frame period; and

adjacent pixels of said plurality of pixels share a power source supply line for supplying a voltage applied to said second electrode,

wherein said EL driving voltage is a difference between said potentials applied to said first and said second electrodes.

17. An electro-optical device according to claim 8, wherein said EL driving TFT and said switching TFT comprise an n-channel type TFT or a p-channel type TFT.

22. An electro-optical device according to claim 8, wherein said light emission of said plurality of EL elements is controlled with said digital data signal input to said switching TFT.

27. An electro-optical device according to claim 8, wherein said one frame period is {fraction (1/120)} s or less.

34. An electro-optical device according to claim 8, wherein said electro-optical device is one selected from the group consisting of a video camera, a digital camera, a head-mount display, a car navigation system, a personal computer, and a DVD player.

9. An electro-optical device comprising a plurality of pixels, said device including a plurality of EL elements, a plurality of EL driving TFTs for controlling light emission of said plurality of EL elements, a plurality of switching TFTs for controlling driving of said plurality of EL driving TFTs, characterized in that:

said electro-optical device provides a gray scale display;

said plurality of EL elements comprise a first electrode and a second electrode; and

a potential of said first or said second electrode changes in such a manner that a polarity of an EL driving voltage is inverted for each one frame period,

wherein said EL driving voltage is a difference between said potentials applied to said first and said second electrodes.

14. An electro-optical device according to claim 9, wherein said EL layer incorporated in said plurality of EL elements comprises a low molecular organic material selected from the group consisting of Alq₃ (tris-80quinolylite-aluminum), and TPD (triphenylamine derivative).

15. An electro-optical device according to claim 9, wherein said EL layer incorporated in said plurality of EL elements comprises a polymer organic material selected from the group consisting of PPV (polyphenylenevynilene), PVK (polyvynil-caracole), and polycarbonate.

18. An electro-optical device according to claim 9, wherein said EL driving TFT and said switching TFT comprise an n-channel type TFT or a p-channel type TFT.

23. An electro-optical device according to claim 9, wherein said light emission of said plurality of EL elements is controlled with said digital data signal input to said switching TFT.

28. An electro-optical device according to claim 9, wherein said one frame period is {fraction (1/120)} s or less.

35. An electro-optical device according to claim 9, wherein said electro-optical device is one selected from the group consisting of a video camera, a digital camera, a head-mount display, a car navigation system, a personal computer, and a DVD player.

10. An electro-optical device comprising a plurality of pixels, said device including a plurality of EL elements, a plurality of EL driving TFTs for controlling light emission of said plurality of EL elements, a plurality of switching TFTs for controlling driving of said plurality of EL driving TFTs, characterized in that:

said electro-optical device provides a gray scale display by inputting an analog video signal to a source region of said switching TFTs;

said plurality of EL elements comprise a first electrode and a second electrode; and

a potential of said first or said second electrode changes in such a manner that a polarity of an EL driving voltage is inverted for each one frame period; and

adjacent pixels of said plurality of pixels share a power source supply line for supplying a voltage applied to said second electrode;

wherein said EL driving voltage is a difference between said potentials applied to said first and said second electrodes.

19. An electro-optical device according to claim 10, wherein said EL driving TFT and said switching TFT comprise an n-channel type TFT or a p-channel type TFT.

24. An electro-optical device according to claim 10, wherein said light emission of said plurality of EL elements is controlled with said digital data signal input to said switching TFT.

29. An electro-optical device according to claim 10, wherein said one frame period is {fraction (1/120)} s or less.

30. An electro-optical device according to claim 10, wherein said EL layer incorporated in said plurality of EL elements comprises a low molecular organic material selected from the group consisting of Alq₃ (tris-80quinolylite-aluminum), and TPD (triphenylamine derivative).

31. An electro-optical device according to claim 10, wherein said EL layer incorporated in said plurality of EL elements comprises a polymer organic material selected from the group consisting of PPV (polyphenylenevynilene), PVK (polyvynil-caracole), and polycarbonate.

36. An electro-optical device according to claim 10, wherein said electro-optical device is one selected from the group consisting of a video camera, a digital camera, a head-mount display, a car navigation system, a personal computer, and a DVD player.

37. An active matrix-type display device comprising:

an EL driving thin film transistor over a substrate;

a switching thin film transistor over the substrate; and

an EL element comprising a first electrode, an organic EL material over the first electrode, and a second electrode over the organic EL material, wherein the EL element is electrically connected to the EL driving thin film transistor,

wherein a gray scale display is provided by inputting an analog video signal to the switching thin film transistor,

wherein a potential of the first or the second electrode changes in such a manner that a polarity of an EL driving voltage is inverted for each one frame period, and

wherein the EL driving voltage is a difference between the potentials applied to the first and the second electrodes.

38. An active matrix-type display device according to claim 37, wherein the one frame period is {fraction (1/120)} s or less.

39. An active matrix-type display device according to claim 37, wherein the organic EL material comprises a low molecular organic material selected from the group consisting of Alq₃ (tris-8-quinolylite-aluminum), and TPD (triphenylamine derivative).

40. An active matrix-type display device according to claim 37, wherein the organic EL material comprises a polymer organic material selected from the group consisting of PPV (polyphenylenevynilene), PVK (polyvynil-caracole), and polycarbonate.

41. An active matrix-type display device according to claim 37, wherein the first electrode is anode and the second electrode is cathode.

42. An active matrix-type display device according to claim 37, wherein the first electrode is cathode and the second electrode is anode.

43. An active matrix-type display device according to claim 37, wherein the active matrix type display device is incorporated in at least one selected from the group consisting of a personal computer, a video camera, a head mount display, a DVD player, a mobile computer, a digital camera, a mobile phone, and an electronic book.

44. An active matrix-type display device comprising:

an EL driving thin film transistor over a substrate;

a switching thin film transistor over the substrate;

an EL element comprising a first electrode, an organic EL material over the first electrode, and a second electrode over the organic EL material, wherein the EL element is electrically connected to the EL driving thin film transistor; and

a driver circuit comprising a plurality of first thin film transistors over the substrate for driving the switching thin film transistor;

a time division gray-scale data signal generating circuit comprising a plurality of second thin film transistors over the substrate for dividing one frame period into a plurality of sub-frame periods,

wherein a gray scale display is provided by controlling a sum of lengths of sub-frame periods in which the EL element emits light out of the plurality of sub-frame periods included in one frame period,

wherein a potential of the first or the second electrode changes in such a manner that a polarity of an EL driving voltage is inverted for each one sub-frame period, and

wherein the EL driving voltage is a difference between the potentials applied to the first and the second electrodes.

45. An active matrix-type display device according to claim 44, wherein the one frame period is {fraction (1/120)} s or less.

46. An active matrix-type display device according to claim 44, wherein the organic EL material comprises a low molecular organic material selected from the group consisting of Alq₃ (tris-8-quinolylite-aluminum), and TPD (triphenylamine derivative).

47. An active matrix-type display device according to claim 44, wherein the organic EL material comprises a polymer organic material selected from the group consisting of PPV (polyphenylenevynilene), PVK (polyvynil-caracole), and polycarbonate.

48. An active matrix-type display device according to claim 44, wherein the first insulating film comprises one selected from the group consisting of polyimide, polyamide, acrylic resin, and BCB (benzocyclobutene).

49. An active matrix-type display device according to claim 44, wherein the second insulating film comprises one selected from the group consisting of silicon oxide, silicon nitride oxide, and an organic resin.

50. An active matrix-type display device according to claim 44, wherein the first electrode is anode and the second electrode is cathode.

51. An active matrix-type display device according to claim 44, wherein the first electrode is cathode and the second electrode is anode.

52. An active matrix-type display device according to claim 44, wherein the active matrix type display device is incorporated in at least one selected from the group consisting of a personal computer, a video camera, a head mount display, a DVD player, a mobile computer, a digital camera, a mobile phone, and an electronic book.

53. An active matrix-type display device comprising:

an EL driving thin film transistor over a substrate;

a switching thin film transistor over the substrate; and

an EL element comprising a first electrode, an organic EL material over the first electrode, and a second electrode over the organic EL material, wherein the EL element is electrically connected to the EL driving thin film transistor,

wherein a gray scale display is provided by controlling a sum of lengths of sub-frame periods in which the EL element emits light out of the plurality of sub-frame periods included in one frame period,

wherein a potential of the second electrode is held constant and a potential of the first electrode changes in such a manner that a polarity of an EL driving voltage is inverted for each one sub-frame period, and

wherein the EL driving voltage is a difference between the potentials applied to the first and the second electrodes.

54. An active matrix-type display device according to claim 53, wherein the one frame period is {fraction (1/120)} s or less.

55. An active matrix-type display device according to claim 53, wherein the organic EL material comprises a low molecular organic material selected from the group consisting of Alq₃ (tris-8-quinolylite-aluminum), and TPD (triphenylamine derivative).

56. An active matrix-type display device according to claim 53, wherein the organic EL material comprises a polymer organic material selected from the group consisting of PPV (polyphenylenevynilene), PVK (polyvynil-caracole), and polycarbonate.

57. An active matrix-type display device according to claim 53, wherein the first insulating film comprises one selected from the group consisting of polyimide, polyamide, acrylic resin, and BCB (benzocyclobutene).

58. An active matrix-type display device according to claim 53, wherein the second insulating film comprises one selected from the group consisting of silicon oxide, silicon nitride oxide, and an organic resin.

59. An active matrix-type display device according to claim 53, wherein the first electrode is anode and the second electrode is cathode.

60. An active matrix-type display device according to claim 53, wherein the first electrode is cathode and the second electrode is anode.

61. An active matrix-type display device according to claim 53, wherein the active matrix type display device is incorporated in at least one selected from the group consisting of a personal computer, a video camera, a head mount display, a DVD player, a mobile computer, a digital camera, a mobile phone, and an electronic book.

62. An active matrix-type display device comprising:

an EL driving thin film transistor over a substrate;

a switching thin film transistor over the substrate;

a first insulating film comprising a resin material over the EL driving thin film transistor and the switching thin film transistor;

a second insulating film on a portion of the first insulating film; and

an EL element comprising a first electrode formed on the first insulating film, an organic EL material over the first electrode, and a second electrode over the organic EL material, wherein the EL element is electrically connected to the EL driving thin film transistor,

wherein a gray scale display is provided by controlling a sum of lengths of sub-frame periods in which the EL element emits light out of the plurality of sub-frame periods included in one frame period,

wherein a potential of the first or the second electrode changes in such a manner that a polarity of an EL driving voltage is inverted for each one sub-frame period, and

wherein the EL driving voltage is a difference between the potentials applied to the first and the second electrodes.

63. An active matrix-type display device according to claim 62, wherein the one frame period is {fraction (1/120)} s or less.

64. An active matrix-type display device according to claim 62, wherein the organic EL material comprises a low molecular organic material selected from the group consisting of Alq₃ (tris-8-quinolylite-aluminum), and TPD (triphenylamine derivative).

65. An active matrix-type display device according to claim 62, wherein the organic EL material comprises a polymer organic material selected from the group consisting of PPV (polyphenylenevynilene), PVK (polyvynil-caracole), and polycarbonate.

66. An active matrix-type display device according to claim 62, wherein the first insulating film comprises one selected from the group consisting of polyimide, polyamide, acrylic resin, and BCB (benzocyclobutene).

67. An active matrix-type display device according to claim 62, wherein the second insulating film comprises one selected from the group consisting of silicon oxide, silicon nitride oxide, and an organic resin.

68. An active matrix-type display device according to claim 62, wherein the first electrode is anode and the second electrode is cathode.

69. An active matrix-type display device according to claim 62, wherein the first electrode is cathode and the second electrode is anode.

70. An active matrix-type display device according to claim 62, wherein the active matrix type display device is incorporated in at least one selected from the group consisting of a personal computer, a video camera, a head mount display, a DVD player, a mobile computer, a digital camera, a mobile phone, and an electronic book.