PWM Pixel Circuit Layout for Threshold Compensation and Dense Integration

Solution Overview

Problem

Conventional pixel circuits for display apparatuses, driven by pulse width modulation and performing internal threshold voltage compensation, require a large number of transistors and capacitors, making them unsuitable for ultra-high-resolution displays due to integration limitations.

Innovation Solution

A pixel circuit design utilizing a reduced number of transistors and capacitors, including specific transistor types and configurations, such as P-type and N-type transistors, to enable internal threshold voltage compensation and pulse width modulation, allowing for high integration and application in ultra-high-resolution displays.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional pixel circuits with internal threshold voltage compensation are used, then threshold voltage compensation is achieved, but the number of transistors increases to 19 or more

Engineering Contradiction:

Improvethreshold voltage compensationVSAvoidnumber of transistors

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the threshold voltage compensation function with the pulse width modulation driving function into a single integrated circuit structure. By combining these previously separate functions, the design achieves threshold voltage compensation without requiring additional transistors beyond the 7 needed for PWM driving, thus resolving the contradiction between reliability (compensation) and device complexity (transistor count).

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The pixel circuit is designed with multi-functional transistors that perform multiple operations. Each transistor serves dual purposes: some transistors are involved in both PWM signal processing and threshold voltage compensation, eliminating the need for dedicated compensation transistors and reducing overall circuit complexity while maintaining compensation capability.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If conventional pixel circuits with internal threshold voltage compensation are used, then threshold voltage compensation is achieved, but integration becomes difficult for ultra-high-resolution displays

Engineering Contradiction:

Improvethreshold voltage compensationVSAvoidintegration

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent merges the threshold voltage compensation function with the pulse width modulation driving function into a single integrated circuit structure. By combining these previously separate functions, the design achieves threshold voltage compensation without requiring additional transistors beyond the 7 needed for PWM driving, thus resolving the contradiction between reliability (compensation) and device complexity (transistor count).

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent utilizes the inherent electrical parameters and timing characteristics of the PWM driving signals to perform threshold voltage compensation. By changing the approach from dedicated compensation circuitry to parameter-based compensation using existing driving waveforms, the design achieves compact integration suitable for ultra-high-resolution displays.

Inventive Principle:

Principle #35Parameter changes

3Ease of manufacture

If a reduced number of transistors is used in the pixel circuit, then integration is improved for ultra-high-resolution displays, but achieving internal threshold voltage compensation becomes more difficult

Engineering Contradiction:

ImproveintegrationVSAvoidthreshold voltage compensation

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The pixel circuit is designed with multi-functional transistors that perform multiple operations. Each transistor serves dual purposes: some transistors are involved in both PWM signal processing and threshold voltage compensation, eliminating the need for dedicated compensation transistors and reducing overall circuit complexity while maintaining compensation capability.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The pixel circuit performs threshold voltage compensation using its own internal PWM driving signals and existing transistor structures, without requiring external compensation circuitry or additional dedicated compensation components. The circuit serves its own compensation needs through self-contained operations during the PWM driving phases.

Inventive Principle:

Principle #25Self-service

Data Source

PatentUS20250342794A1Pixel circuit, display apparatus having the same, and an electronic device including the display device

Publication Date: 2025.11.06 SAMSUNG DISPLAY CO LTD

AI summary

A pixel circuit includes: a first transistor including a control electrode connected to a first node, a first electrode connected to a second node, and a second electrode connected to a third node; a second transistor configured apply a data voltage to the first transistor; a third transistor connected to the first node and the third node; a fourth transistor configured to apply a first power voltage to the second node in response to a first emission signal; a fifth transistor configured to apply a voltage of a fourth node to the third node in response to a second emission signal different from the first emission signal; a seventh transistor configured to apply a driving current to a light emitting element and connected to the fourth node; a ninth transistor configured to apply an initialization voltage to the fourth node.