Pixel Circuit Threshold-Voltage Correction for Uniform Luminance

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Solution Overview

Problem

Active matrix display devices face challenges in maintaining uniform luminance across pixels due to variations in threshold voltage of driving transistors, especially as the number of pixels increases, leading to reduced display quality.

Innovation Solution

A semiconductor device configuration that includes a first transistor, a capacitor, and multiple switches, allowing for independent control of conduction states and threshold voltage correction, which reduces luminance variation between pixels by charging and discharging the gate of the transistor to maintain consistent light emission.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the number of pixels is increased to achieve higher resolution, then display resolution is improved, but variation in threshold voltage of driving transistors increases leading to luminance non-uniformity

Engineering Contradiction:

Improvedisplay resolutionVSAvoidluminance uniformity

Core Design Contradiction:

Measurement precisionVSManufacturing precision

Solution Approach 1:

The patent applies parameter changes by dynamically adjusting the gate voltage of the driving transistor through a correction circuit. The circuit changes the electrical parameters (voltage levels) to compensate for threshold voltage variations, thereby maintaining uniform luminance across pixels even as pixel density increases

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent implements feedback through a correction circuit that monitors and adjusts the gate voltage based on threshold voltage variations. This feedback mechanism detects luminance deviations and applies corrective voltage adjustments to maintain uniform display quality across high-resolution pixel arrays

Inventive Principle:

Principle #23Feedback

2Manufacturing precision

If threshold voltage correction circuits are added to each pixel, then luminance uniformity is improved, but device complexity increases

Engineering Contradiction:

Improveluminance uniformityVSAvoidcircuit complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent merges the correction circuit functionality with the existing pixel circuit structure. By integrating the correction functions into the existing transistor and capacitor architecture, the patent reduces overall device complexity while still achieving threshold voltage correction and luminance uniformity

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS11916088B2Semiconductor device, and module and electronic appliance including the same

Publication Date: 2024.02.27 SEMICON ENERGY LAB CO LTD

AI summary

First to fourth switches are provided so that conduction states are able to be controlled independently of each other. The first switch, the third switch, and the second switch are electrically connected in series between a first wiring and a third wiring. The fourth switch has a function of controlling a conduction state between the light-emitting element and a fourth wiring. In a first transistor, a gate is electrically connected to a node to which the third switch and the second switch are electrically connected, one of a source and a drain is electrically connected to a second wiring, and the other is electrically connected to the light-emitting element. A capacitor includes first and second electrodes, the first electrode is electrically connected to a node to which the first switch and the third switch are electrically connected, and the second electrode is electrically connected to the light-emitting element.