EL Display Subpixel Compensation via Initial Characterization
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Electroluminescent displays, particularly OLEDs, suffer from initial nonuniformities due to variations in drive transistors and OLED emitters, leading to unacceptable display performance, with existing compensation methods being either slow, complex, or limited to passive-matrix displays.
Innovation Solution
A method that compensates for differences in electroluminescent subpixels by using a voltage measurement circuit to assess and correct for variations in drive transistors and OLED emitters, employing a simple and rapid process that doesn't require extensive circuitry or continuous measurement, allowing for unique characterization and compensation of each subpixel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If iterative measurement techniques are used to compensate for pixel performance, then measurement precision is improved, but productivity deteriorates due to slow compensation process
Solution Approach 1:
The patent applies preliminary action by measuring and compensating for initial nonuniformities during the manufacturing process before the display is delivered to customers. This is done through a one-time compensation process that characterizes each subpixel's properties and stores compensation values, eliminating the need for slow iterative measurements after product delivery while maintaining high measurement precision.
2Manufacturing precision
If linear scaling method is used to reduce brightness variations, then manufacturing precision is improved, but device complexity increases due to additional control circuitry
Solution Approach 1:
The patent applies local quality by implementing compensation at the individual subpixel level rather than using global scaling methods. Each subpixel is characterized separately and has its own compensation values stored in lookup tables, allowing precise local correction of nonuniformities without requiring complex real-time control circuitry for each pixel.
Solution Approach 2:
The patent uses copying by creating pre-computed lookup tables that store compensation values for each subpixel based on initial measurements. These lookup tables are copied into the display controller during manufacturing, replacing the need for complex real-time calculation circuitry while maintaining high brightness uniformity across all pixels.
3Measurement precision
If extensive computational circuitry is used to implement uniformity correction, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent applies preliminary action by performing all complex measurements and calculations during the manufacturing process to create lookup tables. The actual display operation then simply retrieves pre-computed compensation values from these tables, eliminating the need for extensive computational circuitry in the final product while maintaining high correction precision.
Solution Approach 2:
The patent uses copying by transferring pre-computed compensation data from manufacturing measurement equipment into lookup tables stored in the display controller. This copying approach replaces complex real-time computational circuitry with simple table lookup operations, reducing device complexity while preserving measurement precision.
Data Source
AI summary
A method of compensating for differences in characteristics of a plurality of electroluminescent (EL) subpixels having readout transistors, includes providing a first voltage source connected through a first switch to each subpixel's drive transistor and a second voltage source connected through a second switch to each subpixel's EL emitter; providing a current source connected through a third switch, and a current sink connected through a fourth switch, to the readout transistor; providing a test voltage to a subpixel; closing only the first and fourth switches and measuring the readout transistor voltage to provide a first signal representative of characteristics of the drive transistor; closing only the second and third switches and measuring the voltage to provide a second signal representative of characteristics of the EL emitter; repeating for each subpixel; and using the first and second signals for each subpixel to compensate for differences in characteristics of the EL subpixels.