Pixel Circuit Sensing for Light-Emitting Element Count Detection
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Solution Overview
Problem
Current display devices face challenges in accurately determining the number of light emitting elements in each sub-light emitting unit, leading to inefficiencies in luminance uniformity and pixel performance.
Innovation Solution
A display device design that includes a pixel structure with multiple transistors and light emitting units connected to sensing lines, allowing for the determination of the number of light emitting elements by measuring currents through these units during a sensing period, using reference voltages to predict the number of elements and compensate for deterioration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional display device structures are used, then device complexity is reduced, but measurement precision of light emitting element count deteriorates
Solution Approach 1:
The light emitting unit is divided into multiple sub light emitting units (first sub light emitting unit, second sub light emitting unit, etc.), each containing a specific number of light emitting elements. This segmentation enables independent measurement of each sub unit's element count through dedicated sensing lines, improving measurement precision while maintaining manageable device complexity through systematic organization.
Solution Approach 2:
Sensing lines are introduced as intermediary components to measure currents flowing through each sub light emitting unit. These sensing lines act as mediators between the light emitting elements and the measurement system, enabling indirect but precise determination of element counts without requiring direct physical access to each element.
2Measurement precision
If multiple sensing lines are added to measure current in each sub light emitting unit, then measurement precision improves, but device complexity increases
Solution Approach 1:
The sensing lines and associated transistors serve multiple functions: they measure currents in different sub light emitting units at different times, enable determination of element counts, and support compensation for pixel deterioration. This multi-functionality reduces the need for separate dedicated components for each measurement task, balancing measurement precision with device complexity.
Solution Approach 2:
The measurement process operates periodically, with control lines enabling sequential activation of different sensing lines at different time periods. During a measurement period, specific sensing lines are activated to measure currents in corresponding sub light emitting units, while other lines remain inactive. This periodic operation allows multiple measurements to be performed using a limited set of components, reducing overall device complexity.
3Measurement precision
If reference voltages are applied during sensing period, then measurement precision improves, but use of energy increases
Solution Approach 1:
Reference voltages are applied only partially in time (during specific sensing periods) and only to specific sensing lines that are actively being used for measurement. Not all sensing lines are activated simultaneously, and reference voltages are applied only when measurements are being performed, rather than continuously. This partial application reduces energy consumption while maintaining measurement precision when needed.
Data Source
AI summary
A pixel includes a first transistor connected between a first power line and a first node, and including a gate electrode connected to a second node, a second transistor connected between a data line and the second node, and including a gate electrode connected to a scan line, a third transistor connected between a first sensing line and the first node, and including a gate electrode connected to a first control line, a fourth transistor connected between a second sensing line and a third node, and including gate electrode connected to a second control line, a first sub light emitting unit including light emitting elements connected in parallel in a forward direction between the first node and the third node, and a second sub light emitting unit including light emitting elements connected in parallel in the forward direction between the third node and a second power line.