Pixel Circuit Drive Transistor Luminance Uniformity Control
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Solution Overview
Problem
Display devices using pixel circuits experience luminance nonuniformity due to resistance components between the reference electric potential point and the display element, affecting both passive and active matrix systems.
Innovation Solution
A pixel circuit is designed with a drive transistor and a characteristics controlling portion to adjust the drive current by controlling the characteristics of the drive transistor, thereby managing luminance and suppressing luminance changes caused by resistance components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a passive matrix system is used to drive the display device, then the structure is simple, but it is difficult to realize large and fine-definition display device
Solution Approach 1:
An active element (transistor) is introduced as an intermediary component within each pixel to control the passive matrix addressing. This transistor acts as a switch that enables fine-definition display capability while maintaining the simpler passive matrix routing structure, resolving the contradiction between structural simplicity and fine-definition capability
2Manufacturing precision
If an active matrix system is used to control pixel signals, then fine-definition display is achieved, but luminance change due to resistance component between reference electric potential point and display element occurs
Solution Approach 1:
A characteristics controlling portion is introduced that provides feedback control of the drive transistor characteristics. This portion detects variations in drive current caused by resistance components and adjusts transistor characteristics (such as threshold voltage) to compensate for these variations, thereby suppressing luminance nonuniformity while maintaining fine-definition capability
3Reliability
If the characteristics of the drive transistor are controlled to adjust drive current, then luminance uniformity is improved, but device complexity increases
Solution Approach 1:
The characteristics controlling portion is designed to perform multiple functions: it controls drive transistor characteristics to compensate for resistance variations, adjusts drive current to maintain luminance uniformity, and integrates with the existing pixel circuit structure. This multi-functionality reduces the need for separate compensation circuits, thereby limiting the increase in device complexity
Data Source
AI summary
Disclosed herein is a pixel circuit, including: a display portion; a drive transistor driving the display portion; and a characteristics controlling portion configured to control characteristics of the drive transistor.