Light emitting device and method of driving the same

• US 20050179628A1
• Filed: 04/07/2005
• Published: 08/18/2005
• Est. Priority Date: 09/07/2001
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Kimura, Hajime
• Granted Patent: US 8,947,328 B2
• Time in Patent Office: Days
• US Class Current: 345/77
• CPC Class Codes: G09G 2300/0842 forming a memory circuit, e.g. a dynamic memory with one capacitor
• CPC Class Codes: G09G 2310/0251 Precharge or discharge of pixel before applying new pixel voltage
• CPC Class Codes: G09G 2320/02 Improving the quality of display appearance
• CPC Class Codes: G09G 2320/0257 Reduction of after-image effects
• CPC Class Codes: G09G 2320/0285 using tables for spatial correction of display data
• CPC Class Codes: G09G 2320/029 by monitoring one or more pixels in the display panel, e.g. by monitoring a fixed reference pixel
• CPC Class Codes: G09G 2320/0295 by monitoring each display pixel
• CPC Class Codes: G09G 2320/043 Preventing or counteracting the effects of ageing
• CPC Class Codes: G09G 2340/14 Solving problems related to the presentation of information to be displayed
• CPC Class Codes: G09G 3/2059 using error diffusion
• CPC Class Codes: G09G 3/22 using controlled light sources
• CPC Class Codes: G09G 3/3233 with pixel circuitry controlling the current through the light-emitting element
• CPC Class Codes: G09G 3/3291 in which the data driver supplies a variable data voltage for setting the current through, or the voltage across, the light-emitting elements

Abstract

The present invention specifies the characteristic of a driving transistor provided in a pixel and corrects a video signal to be inputted to the pixel based on the specification. As a result, a light emitting device and its driving method in which influence of fluctuation in characteristic among transistors is removed to obtain clear multi-gray scale are provided. The present invention can also provide a light emitting device and its driving method in which a change with age in amount of current flowing between two electrodes of a light emitting element is reduced to obtain clear multi-gray scale display.

Claims

1-69. -69. (canceled)

70. A method of driving a light emitting device having a display panel, comprising:

measuring a current value I₀ when every pixel in the display panel is not lit;

measuring current values I₁, I₂, . . . , I_n when one pixel in the display panel is lit; and

correcting video signals to be inputted to pixels of the display panel using current values Q₁, Q₂, . . . , Q_n,

wherein the current values Q₁, Q₂, . . . , Q_n are calculated using the current value I₀ and the current values I₁, I₂, . . . , I_n.

74. The method of driving a light emitting device according to claim 70 further comprising:

controlling a current following between two electrodes of a light emitting element included in the pixels;

controlling input of video signals to the pixels; and

holding the video signals.

75. The method of driving a light emitting device according to claim 74,

wherein the video signals are held in a capacitor element;

and

wherein electric charges are discharged from the capacitor element.

76. The method of driving a light emitting device according to claim 70,

wherein current values I₁, I₂, . . . , I_n are measured when video signals are inputted to the pixels.

77. The method of driving a light emitting device according to claim 70,

wherein the current values I₁, I₂, . . . , I_n are measured before or after an images displayed on the display panel.

71. A method of driving a light emitting device having a display panel, comprising:

measuring a current value I₀ when every pixel in the display panel is not lit;

measuring current values I₁, I₂, . . . , I_n when one pixel in the display panel is lit; and

correcting video signals P₁, P₂, P_n to be inputted to pixels of the display panel using current values Q₁, Q₂, . . . , Q_n,

wherein the current values Q₁, Q₂, . . . , Q_n are calculated using the current value I₀, the current values I₁, I₂, . . . , I_n, and the video signals P₁, P₂, . . . , P_n.

78. The method of driving a light emitting device according to claim 71 further comprising:

controlling a current following between two electrodes of a light emitting element included in the pixels;

controlling input of video signals P₁, P₂, . . . , P_n to the pixels; and

holding the video signals P₁, P₂, . . . , P_n.

79. The method of driving a light emitting device according to claim 78,

wherein the video signals P₁, P₂, . . . , P_n are held in a capacitor element;

and

wherein electric charges are discharged from the capacitor element.

80. The method of driving a light emitting device according to claim 71,

wherein current values I₁, I₂, . . . , I_n are measured when video signals P₁, P₂, . . . , P_n are inputted to the pixels.

81. The method of driving a light emitting device according to claim 71,

wherein the current values I₁, I₂, . . . , I_n are measured before or after an images displayed on the display panel.

72. A method of driving a light emitting device having a display panel, comprising:

measuring a current value I₀ when every pixel in the display panel is not lit;

measuring current values I₁, I₂, . . . , I_n when one pixel in the display panel is lit;

calculating an interpolation function F; and

correcting video signals P₁, P₂, . . . , P_n to be inputted to pixels of the display panel using the interpolation function F,

wherein current values Q₁, Q₂, . . . , Q_n corresponding to the video signals P₁, P₂, . . . , P_n are calculated using the current value I₀ and the current values I₁, I₂, . . . , I_n; and

wherein the interpolation function F is obtained by substituting the video signals P₁, P₂, . . . , P_n and the current values Q₁, Q₂, . . . , Q_n in an expression of Q=F(P).

82. The method of driving a light emitting device according to claim 72 further comprising:

controlling a current following between two electrodes of a light emitting element included in the pixels;

controlling input of video signals P₁, P₂, . . . , P_n to the pixels; and

holding the video signals P₁, P₂, . . . , P_n.

83. The method of driving a light emitting device according to claim 82,

wherein the video signals P₁, P₂, . . . , P_n are held in a capacitor element;

and

wherein electric charges are discharged from the capacitor element.

84. The method of driving a light emitting device according to claim 72,

wherein current values I₁, I₂, . . . , I_n are measured when video signals P₁, P₂, . . . , P_n are inputted to the pixels.

85. The method of driving a light emitting device according to claim 72,

wherein the current values I₁, I₂, . . . , I_n are measured before or after an images displayed on the display panel.

86. The method driving a light emitting device according to claim 72,

wherein the expression of Q=F(P) is expressed as Q=A(P−

B)², Q=a*P+b, a spline function, a Bezier function, or a linear function.

73. A method of driving a light emitting device having a display panel, comprising:

measuring a current value I₀ when every pixel in the display panel is not lit;

measuring current values I₁, I₂, . . . , I_n when one pixel in the display panel is lit;

calculating an interpolation function F;

storing the interpolation function F; and

correcting video signals P₁, P₂, . . . , P_n to be inputted in the pixels of the display panel using the interpolation function F,

wherein current values Q₁, Q₂, . . . , Q_n corresponding to the video signals P₁, P₂, . . . , P_n are calculated using the current value I₀ and the current values I₁, I₂, . . . , I_n; and

wherein the interpolation function F is obtained by substituting the video signals P₁, P₂, . . . , P_n and the current values Q₁, Q₂, . . . , Q_n in an expression of Q=F(P).

87. The method of driving a light emitting device according to claim 73 further comprising:

controlling a current following between two electrodes of a light emitting element included in the pixels;

controlling input of video signals P₁, P₂, . . . , P_n to the pixels; and

holding the video signals P₁, P₂, . . . , P_n.

88. The method of driving a light emitting device according to claim 87,

wherein the video signals P₁, P₂, . . . , P_n are held in a capacitor element;

and

wherein electric charges are discharged from the capacitor element.

89. The method of driving a light emitting device according to claim 73,

wherein current values I₁, I₂, . . . , I_n are measured when video signals P₁, P₂, . . . , P_n are inputted to the pixels.

90. The method of driving a light emitting device according to claim 73,

wherein the current values I₁, I₂, . . . , I_n are measured before or after an images displayed on the display panel, or before the interpolation function is stored.

91. The method driving a light emitting device according to claim 73,

wherein the expression of Q=F(P) is expressed as Q=A(P−

B)², Q=a*P+b, a spline function, a Bezier function, or a linear function.

92. The method of driving a light emitting device according to claim 73,

wherein the interpolation function F is stored in a semiconductor memory or a magnetic memory.