US 8,264,434 B2Granted

Active matrix substrate and drive circuit thereof

AssigneeSharp Kabushiki Kaisha

InventorTakaharu Yamada

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Abstract

An active matrix substrate used in a display device or the like capable of making substantially uniform the level shift generated in the pixel potential caused by the distribution of resistance and capacity in each signal line is disclosed. On the TFT substrate which is an active matrix substrate including a common electrode line formed parallel to the scan signal line, in order to eliminate non-uniformity of the level shift of the pixel potential generated at the scan signal fall, each pixel circuit is formed so that the capacity between the scan signal line and the pixel electrode becomes greater as electrically going farther from the scan signal line drive circuit and going farther from the common electrode line drive circuit. Embodiments can be applied especially to an active matrix substrate used in a liquid crystal display device, an EL display device, and the like.

Claims18

Dependent claims

An active matrix substrate comprising:

data signal lines each for one of data signals;
scanning signal lines crossing with the data signal lines;
and
a matrix of pixel circuits each corresponding to one of intersections made by the data signal lines and the scanning signal lines;
wherein each pixel circuit includes
a field-effect transistor having a source electrode connected with one of the data signal lines that passes through a corresponding one of the intersections, directly or via a switching element and/or a capacity element;
and a gate electrode connected with one of the scanning signal lines that passes through the corresponding intersection;
the field-effect transistor assuming a conductive state upon application of an ON voltage while assuming a nonconductive state upon application of an OFF voltage, to the gate electrode based on the source electrode as a baseline;
and
a voltage holding electrode connected with a drain electrode of the field-effect transistor, providing a voltage holding capacitor;
and
wherein each pixel circuit is formed so that a value given by an equation below will be substantially equal among the pixel circuits
(Vgpp·Cgd+ΔQd)/Cpix
where Vgpp represents an amount of potential change at the gate electrode from a time when a gate signal, which is given to the gate electrode of the field-effect transistor via the scanning signal line, starts its transition from the ON voltage to the OFF voltage to a time when the transition is complete;
Cgd represents an electrostatic capacity between the gate electrode and the drain electrode in the field-effect transistor;
ΔQd represents an amount of charge which moves through the field-effect transistor to the voltage holding electrode from the time when the gate signal starts its transition from the ON voltage to the OFF voltage to the time when the transition is complete;
and Cpix represents a sum of electrostatic capacities formed between the drain electrode of the field-effect transistor or the voltage holding electrode and other electrodes in each pixel circuit.

14 more elements

An active matrix substrate comprising:

data signal lines each for one of data signals;
scanning signal lines crossing with the data signal lines;
a matrix of pixel circuits each corresponding to one of intersections made by the data signal lines and the scanning signal lines;
and
a common electrode line disposed to form an electrostatic capacity in each pixel circuit, an electric potential to be supplied to the common electrode line being applied to one end and another other end of the common electrode line;
wherein each pixel circuit includes
a field-effect transistor having a source electrode connected with one of the data signal lines that passes through a corresponding one of the intersections, directly or via a switching element and/or a capacity element;
a gate electrode connected with one of the scanning signal lines that passes through the corresponding intersection;
and
a voltage holding electrode connected with a drain electrode of the field-effect transistor, providing the electrostatic capacity between itself and the common electrode line;
wherein the pixel circuits include a first, a second and a third pixel circuits, the first pixel circuit being closer to an end of the common electrode line and farther from a center of the common electrode line than the second pixel circuit, the third pixel circuit being closer to another end of the common electrode line and farther from the center of the common electrode line than the second pixel circuit,
an area of overlap between the electrode constituting the scanning signal line that passes through the corresponding intersection and the voltage holding electrode or the drain electrode of the field-effect transistor in the second pixel circuit being greater
than an area of overlap between the electrode constituting the scanning signal line that passes through the corresponding intersection and the voltage holding electrode or the drain electrode of the field-effect transistor in the first pixel circuit, and greater than an area of overlap between the electrode constituting the scanning signal line that passes through the corresponding intersection and the voltage holding electrode or the drain electrode of the field-effect transistor in the third pixel circuit.

10 more elements

An active matrix substrate comprising:

data signal lines each for one of data signals;
scanning signal lines crossing with the data signal lines;
a matrix of pixel circuits each corresponding to one of intersections made by the data signal lines and the scanning signal lines;
and
a common electrode line disposed to form an electrostatic capacity in each pixel circuit, an electric potential to be supplied to the common electrode line being applied to one end and another other end of the common electrode line;
wherein each pixel circuit includes
a field-effect transistor having a source electrode connected with one of the data signal lines that passes through a corresponding one of the intersections, directly or via a switching element and/or a capacity element;
a gate electrode connected with one of the scanning signal lines that passes through the corresponding intersection;
and
a voltage holding electrode connected with a drain electrode of the field-effect transistor, providing the electrostatic capacity between itself and the common electrode line;
wherein the pixel circuits include a first, a second and a third pixel circuits, the first pixel circuit being closer to an end of the common electrode line and farther from a center of the common electrode line than the second pixel circuit, the third pixel circuit being closer to another end of the common electrode line and farther from the center of the common electrode line than the second pixel circuit,
wherein one of the electrostatic capacities which are formed between the drain electrode of the field-effect transistor or the voltage holding electrode and other electrodes in the second circuit other than an electrostatic capacity Cgd between the gate electrode and the drain electrode of the field-effect transistor in the second circuit being smaller than one of the electrostatic capacities which are formed between the drain electrode of the field-effect transistor or the voltage holding electrode and other electrodes in the first circuit other than the electrostatic capacity Cgd between the gate electrode and the drain electrode of the field-effect transistor in the first circuit, and smaller than one of electrostatic capacities which are formed between the drain electrode of the field-effect transistor or the voltage holding electrode and other electrodes in the third circuit other than the electrostatic capacity Cgd between the gate electrode and the drain electrode of the field-effect transistor in the third circuit.

9 more elements

Dependencies are inferred from the claim text.

Facts

Application: 11/631,652Filed 24 Jun 2005
Priority: JP P2004-20773814 Jul 2004
Published: US 2007/0273683 A129 Nov 2007
Granted: 11 Sep 2012
Term ends: Not estimatedThe source records don’t support an estimate.

Classification9 codes

G02F 1/136213
Active matrix addressed cells: storage capacitors associated with the pixel electrode
G09G 3/3655
Using an active matrix: details of drivers for counter electrodes, e.g. common electrodes for pixel capacitors or supplementary storage capacitors
G02F 1/13606
Liquid crystal cells structurally associated with a semi-conducting layer or substrate, e.g. cells forming part of an integrated circuit: having…
G09G 3/3677
Details of drivers for scan electrodes: suitable for active matrices only