Display panel, display panel inspection method, and display panel manufacturing method

• US 20020044124A1
• Filed: 06/05/2001
• Published: 04/18/2002
• Est. Priority Date: 06/05/2000
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Arai, Yasuyuki, Koyama, Jun, Yamazaki, Shunpei
• Granted Patent: US 7,189,585 B2
• Time in Patent Office: Days
• US Class Current: 345/92
• CPC Class Codes: G09G 2300/0842 forming a memory circuit, e.g. a dynamic memory with one capacitor
• CPC Class Codes: G09G 3/006 Electronic inspection or testing of displays and display drivers, e.g. of LED or LCD displays testing individual LED's G01R31/2635; testing lamps G01R31/44; testing of optical features of LCD displays G02F1/1309
• CPC Class Codes: G09G 3/3225 using an active matrix
• 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 27/1259 Multistep manufacturing methods
• CPC Class Codes: H10K 59/12 Active-matrix OLED [AMOLED] displays

Abstract

A method of inspecting a display panel, which is capable of distinguishing between whether an EL panel is a good product or a defective product before sealing of the display panel, is provided. In a first method of inspection, a conductive film is patterned to forming pixel electrodes after measuring the electric current flowing in the conductive film and detecting defective pixels in accordance with the measured values. In a second method of inspection, all of the pixel electrodes are connected by an inspection conductive film, a value of electric current flowing in the inspection conductive film is measured, and the inspection conductive film is removed after detecting defective pixels in accordance with the measured values.

Claims

1. A method of inspecting a display panel in a manufacturing process of said display panel comprising a plurality of pixels each comprising a thin film transistor and a pixel electrode electrically connected to said thin film transistor, said method comprising steps of:

making said thin film transistor in an on state before forming said pixel electrode by patterning a conductive film;

measuring a value of electric current flowing in said conductive film; and

judging whether or not said thin film transistor is defective from said value,

wherein said steps are performed to all of said plurality of pixels in order.

7. A method according to claim 1, wherein an EL layer and an opposing electrode are laminated in order on said pixel electrode after said pixel electrode is formed.

13. A method according to claim 1, wherein said value of electric current flowing in said conductive film is obtained by measuring a value of electric current flowing in a measurement wiring connected to said conductive film.

2. A method of inspecting a display panel in a manufacturing process of said display panel comprising a plurality of pixels each comprising a wiring, a thin film transistor, and a pixel electrode, said method comprising steps of:

making said thin film transistor in an on state by controlling an electric potential of said wiring before forming said pixel electrode by patterning a conductive film;

measuring a value of electric current flowing in said conductive film; and

judging whether or not said thin film transistor said wiring are defective from said value,

wherein said steps are performed to all of said plurality of pixels in order.

8. A method according to claim 2, wherein an EL layer and an opposing electrode are laminated in order on said pixel electrode after said pixel electrode is formed.

14. A method according to claim 2, wherein said value of electric current flowing in said conductive film is obtained by measuring a value of electric current flowing in a measurement wiring connected to said conductive film.

3. A method of inspecting a display panel in a manufacturing process of said display panel comprising a plurality of pixels each comprising a switching thin film transistor, an EL driver thin film transistor, a source signal line, a gate signal line, a power source supply line, and a pixel electrode electrically connected to said EL driver thin film transistor, said method comprising steps of:

making said switching thin film transistor in an on state by controlling an electric potential of said gate signal line, making said EL driver thin film transistor in an on state by controlling an electric potential of said source signal line, and controlling an electric potential of said power source supply line, before forming said pixel electrode by patterning a conductive film;

measuring a value of electric current flowing in said conductive film; and

judging whether or not said switching thin film transistor, said EL driver thin film transistor, said source signal line, said gate signal line, said power source supply line are defective from said value,

wherein said steps are performed to all of said plurality of pixels in order.

9. A method according to claim 3, wherein an EL layer and an opposing electrode are laminated in order on said pixel electrode after said pixel electrode is formed.

15. A method according to claim 3, wherein said value of electric current flowing in said conductive film is obtained by measuring a value of electric current flowing in a measurement wiring connected to said conductive film.

4. A method of inspecting a display panel in a manufacturing process of said display panel comprising a plurality of pixels each comprising a switching thin film transistor, an EL driver thin film transistor, a source signal line, a gate signal line, a power source supply line, and a pixel electrode connected to a drain region of said EL driver thin film transistor, said method comprising steps of:

making said switching thin film transistor in an on state by controlling an electric potential of said gate signal line, making said EL driver thin film transistor in an on state by controlling an electric potential of said source signal line, and controlling an electric potential of said power source supply line, before forming said pixel electrode by patterning a conductive film;

measuring a value of electric current flowing in said conductive film; and

judging whether or not said switching thin film transistor, said EL driver thin film transistor, said source signal line, said gate signal line, said power source supply line are defective from said value,

wherein said steps are performed to all of said plurality of pixels in order.

10. A method according to claim 4, wherein an EL layer and an opposing electrode are laminated in order on said pixel electrode after said pixel electrode is formed.

16. A method according to claim 4, wherein said value of electric current flowing in said conductive film is obtained by measuring a value of electric current flowing in a measurement wiring connected to said conductive film.

5. A method of inspecting a display panel in a manufacturing process of said display panel comprising a plurality of pixels each comprising a first switching thin film transistor, a second switching thin film transistor, an EL driver thin film transistor, a source signal line, a first gate signal line, a second gate signal line, a power source supply line, and a pixel electrode electrically connected to said EL driver thin film transistor, said method comprising steps of:

making said first switching thin film transistor in an on state by controlling an electric potential of said first gate signal line, making said EL driver thin film transistor in an on state by controlling an electric potential of said source signal line, and controlling an electric potential of said power source supply line, before forming said pixel electrode by patterning a conductive film;

measuring a first value of electric current flowing in said conductive film;

making said second switching thin film transistor in an on state by controlling an electric potential of said second gate signal line and making said EL driver thin film transistor in an off state, before forming said pixel electrode by patterning a conductive film;

measuring a second value of electric current flowing in said conductive film;

judging whether or not said first switching thin film transistor, said second switching thin film transistor, said EL driver thin film transistor, said source signal line, said first gate signal line, said second gate signal line, and said power source supply line are defective from said first value and said second value,

wherein said steps are performed to all of said plurality of pixels in order.

11. A method according to claim 5, wherein an EL layer and an opposing electrode are laminated in order on said pixel electrode after said pixel electrode is formed.

17. A method according to claim 5, wherein said first value and said second value of electric current flowing in said conductive film are obtained by measuring values of electric current flowing in a measurement wiring connected to said conductive film, respectively.

25. A method according to claim 19, wherein an EL layer and an opposing electrode are laminated in order on said pixel electrode after said inspection conductive film is removed.

31. A method according to claim 19, wherein said value of electric current flowing in said inspection conductive film is obtained by measuring a value of electric current flowing in a measurement wiring connected to said inspection conductive film.

37. A method according to claim 19, wherein said inspection conductive film is a fluid.

6. A method of inspecting a display panel in a manufacturing process of said display panel comprising a plurality of pixels each comprising a first switching thin film transistor, a second switching thin film transistor, an EL driver thin film transistor, a source signal line, a first gate signal line, a second gate signal line, a power source supply line, and a pixel electrode connected to a drain region said EL driver thin film transistor, said method comprising steps of:

making said first switching thin film transistor in an on state by controlling an electric potential of said first gate signal line, making said EL driver thin film transistor in an on state by controlling an electric potential of said source signal line, and controlling an electric potential of said power source supply line, before forming said pixel electrode by patterning a conductive film;

measuring a first value of electric current flowing in said conductive film;

making said second switching thin film transistor in an on state by controlling an electric potential of said second gate signal line and making said EL driver thin film transistor in an off state, before forming said pixel electrode by patterning a conductive film;

measuring a second value of electric current flowing in said conductive film;

judging whether or not said first switching thin film transistor, said second switching thin film transistor, said EL driver thin film transistor, said source signal line, said first gate signal line, said second gate signal line, and said power source supply line are defective from said first value and said second value,

wherein said steps are performed to all of said plurality of pixels in order.

12. A method according to claim 6, wherein an EL layer and an opposing electrode are laminated in order on said pixel electrode after said pixel electrode is formed.

18. A method according to claim 6, wherein said first value and said second value of electric current flowing in said conductive film are obtained by measuring values of electric current flowing in a measurement wiring connected to said conductive film, respectively.

19. A method of inspecting a display panel in a manufacturing process of said display panel comprising a plurality of pixels each comprising a thin film transistor and a pixel electrode electrically connected to said thin film transistor, said method comprising steps of:

connecting all the pixel electrodes of said plurality of pixels electrically by an inspection conductive layer;

making said thin film transistor in an on state;

measuring a value of electric current flowing in said inspection conductive film;

judging whether or not said thin film transistor is defective from said value; and

removing said inspection conductive film after said judging is performed to all of said plurality of pixels in order.

20. A method of inspecting a display panel in a manufacturing process of said display panel comprising a plurality of pixels each comprising a wiring. a thin film transistor and a pixel electrode electrically connected to said thin film transistor, said method comprising steps of:

connecting all the pixel electrodes of said plurality of pixels electrically by an inspection conductive layer;

making said thin film transistor in an on state by controlling an electric potential of said wiring;

measuring a value of electric current flowing in said inspection conductive film;

judging whether or not said wiring and said thin film transistor is defective from said value; and

removing said inspection conductive film after said judging is performed to all of said plurality of pixels in order.

26. A method according to claim 20, wherein an EL layer and an opposing electrode are laminated in order on said pixel electrode after said inspection conductive film is removed.

32. A method according to claim 20, wherein said value of electric current flowing in said inspection conductive film is obtained by measuring a value of electric current flowing in a measurement wiring connected to said inspection conductive film.

38. A method according to claim 20, wherein said inspection conductive film is a fluid.

21. A method of inspecting a display panel in a manufacturing process of said display panel comprising a plurality of pixels each comprising a switching thin film transistor, an EL driver thin film transistor, a source signal line, a gate signal line, a power source supply line, and a pixel electrode electrically connected to said EL driver thin film transistor, said method comprising steps of:

connecting all the pixel electrodes of said plurality of pixels electrically by an inspection conductive layer;

making said switching thin film transistor in an on state by controlling an electric potential of said gate signal line, making said EL driver thin film transistor in an on state by controlling an electric potential of said source signal line, and controlling an electric potential of said power source supply line;

measuring a value of electric current flowing in said inspection conductive film;

judging whether or not said switching thin film transistor, said EL driver thin film transistor, said source signal line, said gate signal line, said power source supply line are defective from said value; and

removing said inspection conductive film after said judging is performed to all of said plurality of pixels in order.

27. A method according to claim 21, wherein an EL layer and an opposing electrode are laminated in order on said pixel electrode after said inspection conductive film is removed.

33. A method according to claim 21, wherein said value of electric current flowing in said inspection conductive film is obtained by measuring a value of electric current flowing in a measurement wiring connected to said inspection conductive film.

39. A method according to claim 21, wherein said inspection conductive film is a fluid.

22. A method of inspecting a display panel in a manufacturing process of said display panel comprising a plurality of pixels each comprising a switching thin film transistor, an EL driver thin film transistor, a source signal line, a gate signal line, a power source supply line, and a pixel electrode connected to a drain region of said EL driver thin film transistor, said method comprising steps of:

connecting all the pixel electrodes of said plurality of pixels electrically by an inspection conductive layer;

making said switching thin film transistor in an on state by controlling an electric potential of said gate signal line, making said EL driver thin film transistor in an on state by controlling an electric potential of said source signal line, and controlling an electric potential of said power source supply line;

measuring a value of electric current flowing in said inspection conductive film;

judging whether or not said switching thin film transistor, said EL driver thin film transistor, said source signal line, said gate signal line, said power source supply line are defective from said value; and

removing said inspection conductive film after said judging is performed to all of said plurality of pixels in order.

28. A method according to claim 22, wherein an EL layer and an opposing electrode are laminated in order on said pixel electrode after said inspection conductive film is removed.

29. A method according to claim 23, wherein an EL layer and an opposing electrode are laminated in order on said pixel electrode after said inspection conductive film is removed.

30. A method according to claim 24, wherein an EL layer and an opposing electrode are laminated in order on said pixel electrode after said inspection conductive film is removed.

34. A method according to claim 22, wherein said value of electric current flowing in said inspection conductive film is obtained by measuring a value of electric current flowing in a measurement wiring connected to said inspection conductive film.

35. A method according to claim 23, wherein said first value and said second value of electric current flowing in said inspection conductive film are obtained by measuring values of electric current flowing in a measurement wiring connected to said inspection conductive film, respectively.

36. A method according to claim 24, wherein said first value said second value of electric current flowing in said inspection conductive film are obtained by measuring values of electric current flowing in a measurement wiring connected to said inspection conductive film, respectively.

40. A method according to claim 22, wherein said inspection conductive film is a fluid.

41. A method according to claim 23, wherein said inspection conductive film is a fluid.

42. A method according to claim 24, wherein said inspection conductive film is a fluid.

23. A method of inspecting a display panel in a manufacturing process of said display panel comprising a plurality of pixels each comprising a first switching thin film transistor, a second switching thin film transistor, an EL driver thin film transistor, a source signal line, a first gate signal line, a second gate signal line, a power source supply line, and a pixel electrode electrically connected to said EL driver thin film transistor, said method comprising steps of:

connecting all the pixel electrodes of said plurality of pixels electrically by an inspection conductive layer;

making said first switching thin film transistor in an on state by controlling an electric potential of said first gate signal line, making said EL driver thin film transistor in an on state by controlling an electric potential of said source signal line, and controlling an electric potential of said power source supply line;

measuring a first value of electric current flowing in said inspection conductive film;

making said second switching thin film transistor in an on state by controlling an electric potential of said second gate signal line and making said EL driver thin film transistor in an off state;

measuring a second value of electric current flowing in said inspection conductive film;

judging whether or not said first switching thin film transistor, said second switching thin film transistor, said EL driver thin film transistor, said source signal line, said first gate signal line, said second gate signal line, and said power source supply line are defective from said first value and said second value,

removing said inspection conductive film after said judging is performed to all of said plurality of pixels in order.

24. A method of inspecting a display panel in a manufacturing process of said display panel comprising a plurality of pixels each comprising a first switching thin film transistor, a second switching thin film transistor, an EL driver thin film transistor, a source signal line, a first gate signal line, a second gate signal line, a power source supply line, and a pixel electrode connected to a drain region of said EL driver thin film transistor, said method comprising steps of:

connecting all the pixel electrodes of said plurality of pixels electrically by an inspection conductive layer;

making said first switching thin film transistor in an on state by controlling an electric potential of said first gate signal line, making said EL driver thin film transistor in an on state by controlling an electric potential of said source signal line, and controlling an electric potential of said power source supply line;

measuring a first value of electric current flowing in said inspection conductive film;

making said second switching thin film transistor in an on state by controlling an electric potential of said second gate signal line and making said EL driver thin film transistor in an off state;

measuring a second value of electric current flowing in said inspection conductive film;

judging whether or not said first switching thin film transistor, said second switching thin film transistor, said EL driver thin film transistor, said source signal line, said first gate signal line, said second gate signal line, and said power source supply line are defective from said first value and said second value,

removing said inspection conductive film after said judging is performed to all of said plurality of pixels in order.

43. A method of manufacturing a display panel, comprising steps of:

forming a conductive film electrically connected to all of a plurality of thin film transistors and a measurement wiring which are provided on an insulating surface;

making said plurality of thin film transistors in an on state, measuring a value of electric current flowing in said measurement wiring, and judging whether or not said plurality of thin film transistors are defective from said value; and

forming a plurality of pixel electrodes by patterning said conductive film to be electrically connected to said plurality of thin film transistors, respectively.

45. A method of manufacturing a display panel according to claim 43, wherein EL layers and an opposing electrode are laminated in order on said plurality of pixel electrodes after said plurality of said pixel electrodes are formed.

53. A display panel formed by said method according to claim 43.

57. A display panel according to claim 53, wherein a source signal line driver circuit and a gate signal line driver circuit are attached to said display panel to be a display panel comprising an attached driver circuit.

61. A display panel according to claim 53, wherein a source signal line driver circuit, a gate signal line driver circuit, and a controller are attached to said display panel to be a display panel comprising an attached controller and driver circuit.

65. A display panel according to claim 53, wherein a source signal line driver circuit, a gate signal line driver circuit, a controller, and a microcomputer are attached to said display panel to be a display panel comprising an attached microcomputer, controller and driver circuit.

69. A display panel according to claim 53, wherein said display panel is used for one of electronic devices which are an EL display, a video camera, a digital camera, a goggle display device, a navigation system, a sound-reproducing system, a notebook type personal computer, a portable information terminal, and a DVD device.

44. A method of manufacturing a display panel, comprising steps of:

forming an interlayer insulating film to cover a plurality of thin film transistors provided on an insulating surface;

forming contact holes in said interlayer insulating film;

forming a plurality of connecting wirings respectively connected to source regions or drain region of said thin film transistors through said contact holes, and a measurement wiring in contact with said insulating surface;

forming a conductive film electrically connected to said plurality of connecting wirings and said measurement wiring;

making said plurality of thin film transistors in an on state, measuring a value of electric current flowing in said measurement wiring, and judging whether or not said plurality of thin film transistors are defective from said value; and

forming a plurality of pixel electrodes by patterning said conductive film to be electrically connected to said plurality of thin film transistors, respectively.

46. A method of manufacturing a display panel according to claim 44, wherein EL layers and an opposing electrode are laminated in order on said plurality of pixel electrodes after said plurality of said pixel electrodes are formed.

49. A method of manufacturing a display panel according to claim 47, wherein EL layers and an opposing electrode are laminated in order on said plurality of pixel electrode after said inspection conductive film is removed.

50. A method of manufacturing a display panel according to claim 48, wherein EL layers and an opposing electrode are laminated in order on said plurality of pixel electrode after said inspection conductive film is removed

51. A method of manufacturing a display panel according to claim 47, wherein said inspection conductive film is a fluid.

52. A method of manufacturing a display panel according to claim 48, wherein said inspection conductive film is a fluid

54. A display panel formed by said method according to claim 44.

55. A display panel formed by said method according to claim 47.

56. A display panel formed by said method according to claim 48.

58. A display panel according to claim 54, wherein a source signal line driver circuit and a gate signal line driver circuit are attached to said display panel to be a display panel comprising an attached driver circuit.

59. A display panel according to claim 55, wherein a source signal line driver circuit and a gate signal line driver circuit are attached to said display panel to be a display panel comprising an attached driver circuit.

60. A display panel according to claim 56, wherein a source signal line driver circuit and a gate signal line driver circuit are attached to said display panel to be a display panel comprising an attached driver circuit.

62. A display panel according to claim 54, wherein a source signal line driver circuit, a gate signal line driver circuit, and a controller are attached to said display panel to be a display panel comprising an attached controller and driver circuit.

63. A display panel according to claim 55, wherein a source signal line driver circuit, a gate signal line driver circuit, and a controller are attached to said display panel to be a display panel comprising an attached controller and driver circuit.

64. A display panel according to claim 56, wherein a source signal line driver circuit, a gate signal line driver circuit, and a controller are attached to said display panel to be a display panel comprising an attached controller and driver circuit.

66. A display panel according to claim 54, wherein a source signal line driver circuit, a gate signal line driver circuit, a controller, and a microcomputer are attached to said display panel to be a display panel comprising an attached microcomputer, controller and driver circuit.

67. A display panel according to claim 55, wherein a source signal line driver circuit, a gate signal line driver circuit, a controller, and a microcomputer are attached to said display panel to be a display panel comprising an attached microcomputer, controller and driver circuit.

68. A display panel according to claim 56, wherein a source signal line driver circuit, a gate signal line driver circuit, a controller, and a microcomputer are attached to said display panel to be a display panel comprising an attached microcomputer, controller and driver circuit.

70. A display panel according to claim 54, wherein said display panel is used for one of electronic devices which are an EL display, a video camera, a digital camera, a goggle display device, a navigation system, a sound-reproducing system, a notebook type personal computer, a portable information terminal, and a DVD device.

71. A display panel according to claim 55, wherein said display panel is used for one of electronic devices which are an EL display, a video camera, a digital camera, a goggle display device, a navigation system, a sound-reproducing system, a notebook type personal computer, a portable information terminal, and a DVD device.

72. A display panel according to claim 56 wherein said display panel is used for one of electronic devices which are an EL display, a video camera, a digital camera, a goggle display device, a navigation system, a sound-reproducing system, a notebook type personal computer, a portable information terminal, and a DVD device.

47. A method of manufacturing a display panel, comprising steps of:

forming an inspection conductive film electrically connected to all of a plurality of pixel electrodes electrically connected to a plurality of thin film transistors respectively, and a measurement wiring, which are provided on an insulating surface;

making said plurality of thin film transistors in an on state, measuring a value of electric current flowing in said measurement wiring, and judging whether or not said plurality of thin film transistors and said plurality of pixel electrodes are defective from said value; and

removing said inspection conductive film.

48. A method of manufacturing a display panel, comprising steps of:

forming an interlayer insulating film to cover a plurality of thin film transistors provided on an insulating surface;

forming contact holes in said interlayer insulating film;

forming a plurality of connecting wirings respectively connected to source regions or drain region of said thin film transistors through said contact holes, and a measurement wiring in contact with said insulating surface;

forming a conductive film electrically connected to said plurality of connecting wirings;

forming a plurality of pixel electrodes electrically connected to said plurality of thin film transistors respectively by patterning said conductive film;

forming an inspection conductive film electrically connected to all of a plurality of pixel electrodes and said measurement wiring;

making said plurality of thin film transistors in an on state, measuring a value of electric current flowing in said measurement wiring, and judging whether or not said plurality of thin film transistors and said plurality of pixel electrodes are defective from said value; and

removing said inspection conductive film.

73. A method of manufacturing of a display panel comprising a plurality of pixels each comprising a thin film transistor and a pixel electrode electrically connected to said thin film transistor, said method comprising steps of:

making said thin film transistor in an on state before forming said pixel electrode by patterning a conductive film;

measuring a value of electric current flowing in said conductive film; and

judging whether or not said thin film transistor is defective from said value,

wherein said steps are performed to all of said plurality of pixels in order.

76. A method according to claim 73, wherein an EL layer and an opposing electrode are laminated in order on said pixel electrode after said pixel electrode is formed.

79. A method according to claim 73, wherein said value of electric current flowing in said conductive film is obtained by measuring a value of electric current flowing in a measurement wiring connected to said conductive film.

74. A method manufacturing a display panel comprising a plurality of pixels each comprising a switching thin film transistor, an EL driver thin film transistor, a source signal line, a gate signal line, a power source supply line, and a pixel electrode electrically connected to said EL driver thin film transistor, said method comprising steps of:

making said switching thin film transistor in an on state by controlling an electric potential of said gate signal line, making said EL driver thin film transistor in an on state by controlling an electric potential of said source signal line, and controlling an electric potential of said power source supply line, before forming said pixel electrode by patterning a conductive film;

measuring a value of electric current flowing in said conductive film; and

judging whether or not said switching thin film transistor, said EL driver thin film transistor, said source signal line, said gate signal line, said power source supply line are defective from said value,

wherein said steps are performed to all of said plurality of pixels in order.

77. A method according to claim 74, wherein an EL layer and an opposing electrode are laminated in order on said pixel electrode after said pixel electrode is formed.

80. A method according to claim 74, wherein said value of electric current flowing in said conductive film is obtained by measuring a value of electric current flowing in a measurement wiring connected to said conductive film.

75. A method of manufacturing a display panel comprising a plurality of pixels each comprising a first switching thin film transistor, a second switching thin film transistor, an EL driver thin film transistor, a source signal line, a first gate signal line, a second gate signal line, a power source supply line, and a pixel electrode electrically connected to said EL driver thin film transistor, said method comprising steps of:

making said first switching thin film transistor in an on state by controlling an electric potential of said first gate signal line, making said EL driver thin film transistor in an on state by controlling an electric potential of said source signal line, and controlling an electric potential of said power source supply line, before forming said pixel electrode by patterning a conductive film;

measuring a first value of electric current flowing in said conductive film;

making said second switching thin film transistor in an on state by controlling an electric potential of said second gate signal line and making said EL driver thin film transistor in an off state, before forming said pixel electrode by patterning a conductive film;

measuring a second value of electric current flowing in said conductive film;

judging whether or not said first switching thin film transistor, said second switching thin film transistor, said EL driver thin film transistor, said source signal line, said first gate signal line, said second gate signal line, and said power source supply line are defective from said first value and said second value,

wherein said steps are performed to all of said plurality of pixels in order.

78. A method according to claim 75, wherein an EL layer and an opposing electrode are laminated in order on said pixel electrode after said pixel electrode is formed.

81. A method according to claim 75, wherein said first value and said second value of electric current flowing in said conductive film are obtained by measuring values of electric current flowing in a measurement wiring connected to said conductive film, respectively.

82. A method of a manufacturing a display panel comprising a plurality of pixels each comprising a thin film transistor and a pixel electrode electrically connected to said thin film transistor, said method comprising steps of:

connecting all the pixel electrodes of said plurality of pixels electrically by an inspection conductive layer;

making said thin film transistor in an on state;

measuring a value of electric current flowing in said inspection conductive film;

judging whether or not said thin film transistor is defective from said value; and

removing said inspection conductive film after said judging is performed to all of said plurality of pixels in order.

85. A method according to claim 82, wherein an EL layer and an opposing electrode are laminated in order on said pixel electrode after said inspection conductive film is removed.

88. A method according to claim 82, wherein said value of electric current flowing in said inspection conductive film is obtained by measuring a value of electric current flowing in a measurement wiring connected to said inspection conductive film.

91. A method according to claim 82, wherein said inspection conductive film is a fluid.

83. A method manufacturing a display panel comprising a plurality of pixels each comprising a switching thin film transistor, an EL driver thin film transistor, a source signal line, a gate signal line, a power source supply line, and a pixel electrode electrically connected to said EL driver thin film transistor, said method comprising steps of:

connecting all the pixel electrodes of said plurality of pixels electrically by an inspection conductive layer;

making said switching thin film transistor in an on state by controlling an electric potential of said gate signal line, making said EL driver thin film transistor in an on state by controlling an electric potential of said source signal line, and controlling an electric potential of said power source supply line;

measuring a value of electric current flowing in said inspection conductive film;

judging whether or not said switching thin film transistor, said EL driver thin film transistor, said source signal line, said gate signal line, said power source supply line are defective from said value; and

removing said inspection conductive film after said judging is performed to all of said plurality of pixels in order.

86. A method according to claim 83, wherein an EL layer and an opposing electrode are laminated in order on said pixel electrode after said inspection conductive film is removed.

89. A method according to claim 83, wherein said value of electric current flowing in said inspection conductive film is obtained by measuring a value of electric current flowing in a measurement wiring connected to said inspection conductive film.

92. A method according to claim 83, wherein said inspection conductive film is a fluid.

84. A method of manufacturing a display panel comprising a plurality of pixels each comprising a first switching thin film transistor, a second switching thin film transistor, an EL driver thin film transistor, a source signal line, a first gate signal line, a second gate signal line, a power source supply line, and a pixel electrode electrically connected to said EL driver thin film transistor, said method comprising steps of:

connecting all the pixel electrodes of said plurality of pixels electrically by an inspection conductive layer;

making said first switching thin film transistor in an on state by controlling an electric potential of said first gate signal line, making said EL driver thin film transistor in an on state by controlling an electric potential of said source signal line, and controlling an electric potential of said power source supply line;

measuring a first value of electric current flowing in said inspection conductive film;

making said second switching thin film transistor in an on state by controlling an electric potential of said second gate signal line and making said EL driver thin film transistor in an off state;

measuring a second value of electric current flowing in said inspection conductive film;

judging whether or not said first switching thin film transistor, said second switching thin film transistor, said EL driver thin film transistor, said source signal line, said first gate signal line, said second gate signal line, and said power source supply line are defective from said first value and said second value,

removing said inspection conductive film after said judging is performed to all of said plurality of pixels in order.

87. A method according to claim 84, wherein an EL layer and an opposing electrode are laminated in order on said pixel electrode after said inspection conductive film is removed.

90. A method according to claim 84, wherein said first value and second value of electric current flowing in said inspection conductive film is obtained by measuring values of electric current flowing in a measurement wiring connected to said inspection conductive film, respectively.

93. A method according to claim 84, wherein said inspection conductive film is a fluid.