US 8,477,085 B2Granted

Semiconductor device and driving method thereof

AssigneeSemiconductor Energy Laboratory Co., Ltd.

InventorHideaki Shishido

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Abstract

A display device which can compensate for variations of the threshold voltage of transistors and suppress variations in luminance, and a driving method thereof are provided. Current is supplied to a light emitting element and light is emitted from the light emitting element by following steps: in the first period initial voltage is stored in a storage capacitor; in the second period, voltage based on video signal voltage and the threshold voltage of the transistor is stored in the storage capacitor; and in the third period, the voltage stored in the storage capacitor in the second period is applied to a gate electrode of the transistor. By these operation processes, the current which compensates the effect of the variations of the threshold voltage of the transistor can be supplied to the light emitting element. Therefore, variations in luminance are suppressed.

Claims26

Dependent claims

A semiconductor device comprising:

a signal line;
a capacitor line;
a power supply line;
a first scan line;
a second scan line;
and
a first pixel and a second pixel, each of the first pixel and the second pixel comprising:
a load;
a first transistor;
a second transistor;
and
a capacitor comprising a third transistor comprising:
a semiconductor layer electrically connected to a first electrode of the capacitor,
a gate electrode electrically connected to a second electrode of the capacitor, and
a gate insulating film interposed between the semiconductor layer and the gate electrode,
wherein a first terminal of the first transistor of each of the first pixel and the second pixel is electrically connected to the signal line and the power supply line,
wherein a second terminal of the first transistor of each of the first pixel and the second pixel is electrically connected to the load of the corresponding one of the first pixel and the second pixel,
wherein a first terminal of the second transistor of each of the first pixel and the second pixel is electrically connected to a gate of the first transistor of the corresponding one of the first pixel and the second pixel,
wherein a second terminal of the second transistor of each of the first pixel and the second pixel is electrically connected to the second terminal of the first transistor of the corresponding one of the first pixel and the second pixel,
wherein a gate of the second transistor of the first pixel is electrically connected to the first scan line,
wherein a gate of the second transistor of the second pixel is electrically connected to the second scan line,
wherein the first electrode of the capacitor of each of the first pixel and the second pixel is electrically connected to the gate of the first transistor of the corresponding one of the first pixel and the second pixel,
wherein the second electrode of the capacitor of each of the first pixel and the second pixel is electrically connected to the capacitor line,
wherein each of the first transistor, the second transistor, and the third transistor of each of the first pixel and the second pixel is a p-channel transistor, and
wherein a potential of the first electrode of the capacitor of each of the first pixel and the second pixel is higher than a potential of the capacitor line.

22 more elements

A semiconductor device comprising:

a signal line;
a capacitor line;
a first power supply line;
a second power supply line;
a first scan line;
a second scan line;
and
a first pixel and a second pixel, each of the first pixel and the second pixel comprising:
a load;
a first transistor;
a second transistor;
a third transistor;
a fourth transistor;
a fifth transistor;
and
a capacitor comprising a sixth transistor comprising:
a semiconductor layer electrically connected to a first electrode of the capacitor,
a gate electrode electrically connected to a second electrode of the capacitor, and
a gate insulating film interposed between the semiconductor layer and the gate electrode,
wherein a first terminal of the first transistor of each of the first pixel and the second pixel is electrically connected to the signal line through the third transistor of the corresponding one of the first pixel and the second pixel, and to the first power supply line through the fourth transistor of the corresponding one of the first pixel and the second pixel,
wherein a second terminal of the first transistor of each of the first pixel and the second pixel is electrically connected to the load of the corresponding one of the first pixel and the second pixel through the fifth transistor of the corresponding one of the first pixel and the second pixel,
wherein a first terminal of the second transistor of each of the first pixel and the second pixel is electrically connected to a gate of the first transistor of the corresponding one of the first pixel and the second pixel,
wherein a second terminal of the second transistor of each of the first pixel and the second pixel is electrically connected to the second terminal of the first transistor of the corresponding one of the first pixel and the second pixel,
wherein a gate of the second transistor of the first pixel is electrically connected to the first scan line,
wherein a gate of the second transistor of the second pixel is electrically connected to the second scan line,
wherein the first electrode of the capacitor of each of the first pixel and the second pixel is electrically connected to the gate of the first transistor of the corresponding one of the first pixel and the second pixel,
wherein the second electrode of the capacitor of each of the first pixel and the second pixel is electrically connected to the capacitor line,
wherein each of the first transistor, the second transistor, the third transistor, the fourth transistor, the fifth transistor, and the sixth transistor of each of the first pixel and the second pixel is a p-channel transistor, and
wherein a potential of the first electrode of the capacitor of each of the first pixel and the second pixel is higher than a potential of the capacitor line.

26 more elements

A driving method of a semiconductor device comprising:

a signal line;
a capacitor line;
a power supply line;
a first scan line;
a second scan line;
and
a first pixel and a second pixel, each of the first pixel and the second pixel comprising:
a load;
a first transistor;
a second transistor;
and
a capacitor comprising a third transistor comprising:
a semiconductor layer electrically connected to a first electrode of the capacitor,
a gate electrode electrically connected to a second electrode of the capacitor, and
a gate insulating film interposed between the semiconductor layer and the gate electrode,
wherein a first terminal of the first transistor of each of the first pixel and the second pixel is electrically connected to the signal line and the power supply line,
wherein a second terminal of the first transistor of each of the first pixel and the second pixel is electrically connected to the load of the corresponding one of the first pixel and the second pixel,
wherein a first terminal of the second transistor of each of the first pixel and the second pixel is electrically connected to a gate of the first transistor of the corresponding one of the first pixel and the second pixel,
wherein a second terminal of the second transistor of each of the first pixel and the second pixel is electrically connected to the second terminal of the first transistor of the corresponding one of the first pixel and the second pixel,
wherein a gate of the second transistor of the first pixel is electrically connected to the first scan line,
wherein a gate of the second transistor of the second pixel is electrically connected to the second scan line,
wherein the first electrode of the capacitor of each of the first pixel and the second pixel is electrically connected to the gate of the first transistor of the corresponding one of the first pixel and the second pixel, and
wherein the second electrode of the capacitor of each of the first pixel and the second pixel is electrically connected to the capacitor line,
the method comprising the steps of:
supplying an initial potential from an initializing line which is electrically connected to the first terminal of the first transistor of each of the first pixel and the second pixel via an initial transistor of the corresponding one of the first pixel and the second pixel;
applying a first voltage to the first scan line;
supplying current corresponding to a first video signal from the signal line to the capacitor of the first pixel via the first transistor of the first pixel and the second transistor of the first pixel to charge a voltage corresponding to the first video signal;
applying the first voltage to the second scan line;
and
supplying current corresponding to a second video signal from the signal line to the capacitor of the second pixel via the first transistor of the second pixel and the second transistor of the second pixel to charge a voltage corresponding to the second video signal.

27 more elements

A driving method of a semiconductor device comprising:

a signal line;
a capacitor line;
a first power supply line;
a second power supply line;
a first scan line;
a second scan line;
and
a first pixel and a second pixel, each of the first pixel and the second pixel comprising:
a load;
a first transistor;
a second transistor;
a third transistor;
a fourth transistor;
a fifth transistor;
and
a capacitor comprising a sixth transistor comprising:
a semiconductor layer electrically connected to a first electrode of the capacitor,
a gate electrode electrically connected to a second electrode of the capacitor, and
a gate insulating film interposed between the semiconductor layer and the gate electrode,
wherein a first terminal of the first transistor of each of the first pixel and the second pixel is electrically connected to the signal line through the third transistor of the corresponding one of the first pixel and the second pixel, and to the first power supply line through the fourth transistor of the corresponding one of the first pixel and the second pixel,
wherein a second terminal of the first transistor of each of the first pixel and the second pixel is electrically connected to the load of the corresponding one of the first pixel and the second pixel through the fifth transistor of the corresponding one of the first pixel and the second pixel,
wherein a first terminal of the second transistor of each of the first pixel and the second pixel is electrically connected to a gate of the first transistor of the corresponding one of the first pixel and the second pixel,
wherein a second terminal of the second transistor of each of the first pixel and the second pixel is electrically connected to the second terminal of the first transistor of the corresponding one of the first pixel and the second pixel,
wherein a gate of the second transistor of the first pixel is electrically connected to the first scan line,
wherein a gate of the second transistor of the second pixel is electrically connected to the second scan line,
wherein the first electrode of the capacitor of each of the first pixel and the second pixel is electrically connected to the gate of the first transistor of the corresponding one of the first pixel and the second pixel, and
wherein the second electrode of the capacitor of each of the first pixel and the second pixel is electrically connected to the capacitor line,
the method comprising the steps of:
supplying an initial potential from an initializing line which is electrically connected to the first terminal of the first transistor of each of the first pixel and the second pixel via an initial transistor of the corresponding one of the first pixel and the second pixel;
applying a first voltage to the first scan line;
supplying current corresponding to a first video signal from the signal line to the capacitor of the first pixel via the first transistor of the first pixel and the second transistor of the first pixel to charge a voltage corresponding to the first video signal;
applying the first voltage to the second scan line;
and
supplying current corresponding to a second video signal from the signal line to the capacitor of the second pixel via the first transistor of the second pixel and the second transistor of the second pixel to charge a voltage corresponding to the second video signal.

31 more elements

Dependencies are inferred from the claim text.

Facts

Application: 11/951,817Filed 6 Dec 2007
Priority: JP 2006-33898915 Dec 2006
Published: US 2008/0143653 A119 Jun 2008
Granted: 2 Jul 2013
Term ends: Not estimatedThe source records don’t support an estimate.

Classification11 codes

G09G 3/3233
Using an active matrix: with pixel circuitry controlling the current through the light-emitting element
G09G 2300/0819
Several active elements per pixel in active matrix panels: used for counteracting undesired variations, e.g. feedback or autozeroing
G09G 2300/0842
Several active elements per pixel in active matrix panels: forming a memory circuit, e.g. a dynamic memory with one capacitor
G09G 2300/0861
Forming a memory circuit, e.g. a dynamic memory with one capacitor: with additional control of the display period without amending the charge…