OLED Pixel Circuit Double-Gate Transistor Leakage Suppression

Solution Overview

Problem

Existing OLED display panels face issues with leakage current affecting the stability of the gate voltage of driving transistors, leading to unstable brightness and screen flickering, especially at low refresh rates.

Innovation Solution

Incorporating a double-gate transistor with a voltage regulation module in the pixel circuit, where the second scan signal has a phase opposite to the first scan signal, to reduce leakage current and stabilize the gate voltage of the driving transistor.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional pixel circuit with a single-gate transistor is used, then the device complexity is low, but the gate voltage stability deteriorates due to leakage current

Engineering Contradiction:

Improvegate voltage stabilityVSAvoidpixel circuit complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The pixel circuit is segmented by dividing the single-gate transistor into a double-gate transistor structure with separate first and second gates. The first gate receives a first scan signal while the second gate receives a second scan signal with opposite phase, allowing independent control of each gate to suppress leakage current and improve gate voltage stability without significantly increasing overall circuit complexity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention employs periodic alternating scan signals with opposite phases applied to the two gates of the double-gate transistor. During the first half-cycle, the first gate is activated while the second gate is deactivated, and during the second half-cycle, the roles are reversed. This periodic action continuously suppresses leakage current paths, maintaining stable gate voltage throughout the refresh cycle.

Inventive Principle:

Principle #19Periodic action

2Reliability

If a conventional pixel circuit is used, then the manufacturing process is simple, but the display quality deteriorates due to screen flickering at low refresh rates

Engineering Contradiction:

Improvedisplay qualityVSAvoidpixel circuit structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The pixel circuit is segmented by dividing the single-gate transistor into a double-gate transistor structure with separate first and second gates. The first gate receives a first scan signal while the second gate receives a second scan signal with opposite phase, allowing independent control of each gate to suppress leakage current and improve gate voltage stability without significantly increasing overall circuit complexity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention employs periodic alternating scan signals with opposite phases applied to the two gates of the double-gate transistor. During the first half-cycle, the first gate is activated while the second gate is deactivated, and during the second half-cycle, the roles are reversed. This periodic action continuously suppresses leakage current paths, maintaining stable gate voltage throughout the refresh cycle.

Inventive Principle:

Principle #19Periodic action

3Use of energy by moving object

If the refresh rate is reduced to save energy, then the energy consumption decreases, but the brightness stability deteriorates leading to screen flickering

Engineering Contradiction:

Improveenergy consumptionVSAvoidbrightness stability

Core Design Contradiction:

Use of energy by moving objectVSStability of the object's composition

Solution Approach 1:

The invention employs periodic alternating scan signals with opposite phases applied to the two gates of the double-gate transistor. During the first half-cycle, the first gate is activated while the second gate is deactivated, and during the second half-cycle, the roles are reversed. This periodic action continuously suppresses leakage current paths, maintaining stable gate voltage throughout the refresh cycle.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The double-gate transistor structure ensures continuous suppression of leakage current by maintaining at least one active gate control throughout the entire refresh cycle. The opposite-phase scan signals ensure that when one gate is deactivated, the other remains active to prevent leakage, providing continuous stabilization of the gate voltage and preventing brightness flickering even at low refresh rates.

Inventive Principle:

Principle #20Continuity of useful action

Data Source

PatentUS12094416B1Display panel and display device

Publication Date: 2024.09.17 WUHAN TIANMA MICRO ELECTRONICS CO LTD

AI summary

A display panel and a display device are provided. The display panel includes a plurality of sub-pixels. Each sub-pixel includes a pixel circuit and a light-emitting element. The pixel circuit includes a driving module, a compensation module, and a voltage regulation module. The compensation module includes a first double-gate transistor, and the first double-gate transistor includes a middle node. First and second electrodes of the first double-gate transistor are electrically connected to a control terminal and a second terminal of the driving module, respectively. A gate of the first double-gate transistor is connected to a first scan line providing a first scan signal. First and second terminals of the voltage regulation module are electrically connected to the middle node and a second scan line providing a second scan signal, respectively. A phase of the second scan signal is opposite to a phase of the first scan signal.