Pixel circuit, display device, and driving method of pixel circuit
First Claim
1. A pixel circuit for driving an electro-optic element with a luminance changing according to a flowing current, comprising:
- a data line through which a data signal in accordance with luminance information is supplied;
a first control line;
first, second, and third nodes;
first and second reference potentials;
a reference current supplying means for supplying a predetermined reference current;
a drive transistor forming a current supply line between a first terminal and a second terminal connected to said first node and controlling a current flowing through said current supply line in accordance with the potential of the control terminal connected to said second node;
a first switch connected to said first node;
a second switch connected between said first node and said second node;
a third switch connected between said data line and said third node and controlled in conduction by said first control line;
a fourth switch connected between said first node and said reference current supplying means; and
a coupling capacitor connected between said second node and said third node, wherein the current supply line of said drive transistor, said first node, said first switch, and said electro-optic element are connected in series between said first reference potential and second reference potential.
1 Assignment
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Accused Products
Abstract
A pixel circuit able to stably and correctly supply a current having a desired value to a light emitting diode of each pixel without being influenced by variation of a threshold value of an active element inside the pixel or variation of mobility and able to display a high quality image as a result of this, wherein a TFT as a fourth switch is turned on together with a TFT as a second switch at the time of an auto-zero operation, a reference current line is connected to a drive transistor of the pixel through a first node, and the variation of the threshold value Vth is corrected, whereby variation of the on current due to the mobility at the time of a white display can be suppressed and the uniformity with respect to variation in the mobility can be greatly enhanced, and a display device and a driving method of the pixel circuit.
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Citations
19 Claims
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1. A pixel circuit for driving an electro-optic element with a luminance changing according to a flowing current, comprising:
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a data line through which a data signal in accordance with luminance information is supplied;
a first control line;
first, second, and third nodes;
first and second reference potentials;
a reference current supplying means for supplying a predetermined reference current;
a drive transistor forming a current supply line between a first terminal and a second terminal connected to said first node and controlling a current flowing through said current supply line in accordance with the potential of the control terminal connected to said second node;
a first switch connected to said first node;
a second switch connected between said first node and said second node;
a third switch connected between said data line and said third node and controlled in conduction by said first control line;
a fourth switch connected between said first node and said reference current supplying means; and
a coupling capacitor connected between said second node and said third node, wherein the current supply line of said drive transistor, said first node, said first switch, and said electro-optic element are connected in series between said first reference potential and second reference potential. - View Dependent Claims (2, 3, 4, 5)
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6. A display device comprising:
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a plurality of pixel circuits arranged in a matrix;
a data line laid for every column of the matrix array of said pixel circuits and supplied with a data signal in accordance with the luminance information;
a first control line laid for every row of the matrix array of said pixel circuit;
first and second reference potentials; and
a reference current supplying means for supplying a predetermined reference current, wherein each pixel circuit has;
first, second, and third nodes, a drive transistor for forming a current supply line between the first terminal and the second terminal connected to said first node and controlling the current flowing through said current supply line in accordance with the potential of the control terminal connected to said second node, a first switch connected to said first node, a second switch connected between said first node and said second node, a third switch connected between said data line and said third node and controlled in conduction by said first control line, a fourth switch connected between said first node and said reference current supplying means, and a coupling capacitor connected between said second node and said third node, and the current supply line of said drive transistor, said first node, said first switch, and said electro-optic element are connected in series between said first reference potential and second reference potential. - View Dependent Claims (7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A display device comprising:
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a plurality of pixel circuits arranged in a matrix;
a data line laid for every column of the matrix array of said pixel circuits and supplied with a data signal in accordance with luminance information;
a first control line laid for every row of the matrix array of said pixel circuits; and
first and second reference potentials, wherein each pixel circuit has;
a reference current supplying means for supplying a predetermined reference current, first, second, and third nodes, a drive transistor for forming a current supply line between the first terminal and the second terminal connected to said first node and controlling the current flowing through said current supply line in accordance with the potential of the control terminal connected to said second node, a first switch connected to said first node, a second switch connected between said first node and said second node, a third switch connected between said data line and said third node and controlled in conduction by said first control line, a fourth switch connected between said first node and said reference current supplying means, and a coupling capacitor connected between said second node and said third node, and the current supply line of said drive transistor, said first node, said first switch, and said electro-optic element are connected in series between said first reference potential and second reference potential.
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19. A driving method of a pixel circuit comprising:
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an electro-optic element with a luminance changing according to the flowing current, a data line supplied with the data signal in accordance with luminance information, first, second, and third nodes, a reference current supplying means for supplying a predetermined reference current, a drive transistor for forming a current supply line between the first terminal and the second terminal connected to said first node and controlling the current flowing through said current supply line in accordance with the potential of the control terminal connected to said second node, a first switch connected to said first node, a second switch connected between said first node and said second node, a third switch connected between said data line and said third node and controlled in conduction by said first control line, a fourth switch connected between said first node and said reference current supplying means, and a coupling capacitor connected between said second node and said third node, and the current supply line of said drive transistor, said first node, said first switch, and said electro-optic element are connected in series between said first reference potential and second reference potential, comprising;
making said second switch and said fourth switch conductive for a predetermined time to electrically connect said first node and said second node and supplying a reference current to the first node, holding said second switch and said third switch in the non-conductive state after the elapse of a predetermined time, making said third switch conductive, making said first switch conductive, and writing data propagated through said data line into said third node, then holding said third switch in the non-conductive state and supplying current in accordance with said data signal to said electro-optic element.
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Specification