Pixel circuit

Patent metadata

Field	Value
Publication number	US-2020243001-A1
Application number	US-202016734455-A
Country	US
Kind code	A1
Filing date	Jan 6, 2020
Priority date	Jan 29, 2019
Publication date	Jul 30, 2020
Grant date	—

Abstract

A pixel circuit is disclosed herein, which includes a first switch, a capacitor, a driving transistor, and a light-emitting diode (LED). The first switch outputs voltage data in response to a scan signal. A first terminal of the capacitor and the first switch are coupled to a node. A second terminal of the capacitor receives a reference signal. The driving transistor is coupled to the node, and configured to output current according to a voltage stored in the node. The LED is coupled to the driving transistor, and emits light according to the current. The reference voltage is different during different operation periods. The driving transistor outputs a first current according to the voltage data and the voltage difference, and outputs a second current according to the voltage data during different operation periods, such that the LED emits a first light and a second light during different operation periods.

First claim

What is claimed is:

1 . A pixel circuit, comprising:
a first switch, configured to output a data voltage in response to a scan signal; a capacitor, wherein the capacitor comprises:
a first terminal, wherein the first terminal and the first switch are coupled to a node; and
a second terminal, configured to receive a reference signal;
a driving transistor, coupled to the node, wherein the driving transistor outputs a current according to a voltage of the node; and a light emitting diode (LED), coupled to the driving transistor, wherein the LED emits light according to the current; wherein the data voltage is written to the node by the first switch, the reference signal is changed to different voltages during different operation periods, the capacitor couples a voltage difference between the different voltages to the node according to the reference signal, wherein the driving transistor outputs a first current respectively according to the data voltage and the voltage difference, and outputs a second current according to the data voltage during different operation periods, such that the LED emits a first brightness light according to the first current and emits a second brightness light according to the second current during different operation periods.

2 . The pixel circuit of claim 1 , wherein in a first period, the data voltage is written to the node by the first switch, and the reference voltage comprises a first voltage, wherein in a second period, the reference signal comprises a second voltage, the capacitor couples the voltage difference between the second voltage and the first voltage to the node, the driving transistor outputs the first current according to the data voltage and the voltage difference, such that the LED emits the first brightness light according to the first current.

3 . The pixel circuit of claim 2 , wherein in a third period, the reference signal comprises the first voltage, the driving transistor generates the second current according to the data voltage, such that the LED emits the second brightness light according to the second current.

4 . The pixel circuit of claim 3 , wherein the first voltage is greater the second voltage.

5 . The pixel circuit of claim 4 , wherein the first current is greater the second current.

6 . The pixel circuit of claim 4 , further comprising:
a second switch, coupled to the driving transistor, wherein the second switch outputs the first current to the LED in the second period and outputs the second current to the LED in the third period according to a control signal.

7 . The pixel circuit of claim 6 , wherein in the second period, a period during which the second switch is turned on partially overlaps a period during which the reference signal is the second voltage.

8 . The pixel circuit of claim 6 , further comprising:
a third switch, coupled to the LED, wherein the third switch resets a voltage of an anode terminal of the LED in the first period according to the scan signal.

9 . The pixel circuit of claim 6 , further comprising:
a third switch, coupled between the LED and the second terminal of the capacitor, wherein the third switch resets a voltage of an anode of the LED in the first period according to the scan signal and the reference voltage.

10 . The pixel circuit of claim 1 , wherein the scan signal comprises a present stage scan signal, and the reference signal comprises a next stage scan signal.

11 . A pixel circuit, comprising:
a first switch; a capacitor, wherein the capacitor comprises: a first terminal, wherein the first terminal and the first switch are coupled to a node; and a second terminal, configured to receive a reference signal; a driving transistor, coupled to the node, wherein the driving transistor outputs a current according to a voltage of the node; and a light emitting diode (LED), coupled to the driving transistor, wherein the LED emits light according to the current; wherein in a first period, the first switch outputs a data voltage to the node in response to a scan signal, and the reference voltage comprises a first voltage, wherein in a second period, the reference signal comprises a second voltage, the driving transistor outputs a first current to the LED according to the voltage of the node, wherein in a third period, the reference signal comprises the first voltage, the driving transistor outputs a second current to the LED according to the voltage of the node.

12 . The pixel circuit of claim 11 , further comprising:
a second switch, coupled to the driving transistor, wherein the second switch outputs the first current to the LED in the second period and outputs the second current to the LED in the third period according to a control signal.

13 . The pixel circuit of claim 11 , further comprising:
a third switch, coupled to the LED, wherein the third switch resets a voltage of an anode of the LED according to the scan signal.

14 . The pixel circuit of claim 11 , further comprising:
a third switch, coupled between the LED and the second terminal of capacitor, wherein the third switch resets a voltage of an anode of the LED in the first period according to the scan signal and the reference voltage.

15 . The pixel circuit of claim 11 , wherein the scan signal comprises a present stage scan signal, and the reference signal comprises a next stage scan signal.

Assignees

• Au Optronics Corp

Inventors

• Chen Yi-Chiung
• Cheng Mao-Hsun

Classifications

• G09G2320/045

  Compensation of drifts in the characteristics of light emitting or modulating elements · CPC title

• G09G2320/0257

  Reduction of after-image effects · CPC title

• G09G2320/0247

  Flicker reduction other than flicker reduction circuits used for single beam cathode-ray tubes · CPC title

• G09G2320/0233

  Improving the luminance or brightness uniformity across the screen · CPC title

• G09G2300/0861

  with additional control of the display period without amending the charge stored in a pixel memory, e.g. by means of additional select electrodes · CPC title