Pixel Circuit Voltage Compensation Without Sensing Line

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Solution Overview

Problem

Existing AMOLED display pixel circuits require a sensing line for voltage compensation, leading to excessive wiring and increased layout space, which is detrimental to high PPI displays and narrow bezel designs, and results in higher costs.

Innovation Solution

A pixel circuit design that eliminates the need for a sensing line by using a data line for voltage compensation, where the fourth transistor is only turned on during the sense period for voltage sensing, allowing for reduced layout space and cost-effective production.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a sensing line is used for voltage compensation in pixel circuits, then voltage compensation can be performed, but the layout space increases and wiring becomes excessive

Engineering Contradiction:

Improvevoltage compensationVSAvoidlayout space

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The patent combines the sensing function with the existing data line by using the fourth transistor to selectively connect the sensing node to the data line during the sense period. This merging eliminates the need for a separate sensing line while maintaining voltage compensation capability, thereby reducing layout space and wiring complexity.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The data line is given dual functionality: it serves both as a data transmission line and as a sensing line for voltage compensation. The fourth transistor enables the data line to perform the sensing function during specific time periods, making the circuit more space-efficient by eliminating dedicated sensing line infrastructure.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If a sensing line is used for voltage compensation, then compensation accuracy is maintained, but production cost increases

Engineering Contradiction:

Improvecompensation accuracyVSAvoidproduction cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

By merging the sensing function into the existing data line infrastructure, the patent reduces the number of required circuit elements and wiring connections. This simplification directly lowers production costs while maintaining compensation accuracy through the selective activation of the fourth transistor during the sense period.

Inventive Principle:

Principle #5Merging (Combining)

3Reliability

If the fourth transistor is activated continuously, then voltage sensing is always available, but power consumption increases

Engineering Contradiction:

Improvevoltage sensing availabilityVSAvoidpower consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The fourth transistor is activated periodically only during the sense period rather than continuously. This periodic activation is controlled by the timing signal, enabling voltage sensing to be performed at appropriate intervals while keeping the transistor off during other periods, thereby significantly reducing power consumption while maintaining sensing availability when needed.

Inventive Principle:

Principle #19Periodic action

Data Source

PatentUS11074868B2Pixel circuit, display panel and display device

Publication Date: 2021.07.27 HEFEI BOE ZHUOYIN TECH CO LTD

AI summary

Embodiments of the present disclosure provide a pixel circuit, a display panel, and a display device. The pixel circuit includes: a first transistor; a light emitting unit, a cathode being grounded; a second transistor; a third transistor; a fourth transistor; and a capacitor, a first terminal being coupled to the control electrode of the third transistor, and a second terminal being coupled to the second electrode of the third transistor.