OLED Driver IC Sensing Threshold Voltage via Data Lines
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Solution Overview
Problem
Existing OLED displays face challenges in accurately sensing the threshold voltage of organic light emitting diodes (OLEDs) without reducing the line design margin of the display panel, leading to luminance variations and image sticking phenomena due to varying degradation across pixels.
Innovation Solution
An electroluminescent display system that utilizes a driver integrated circuit connected to data lines to sense electrical characteristics of OLEDs through a data line, employing a method involving programming periods, degradation tracking, and sensing periods to read voltage changes, allowing for threshold voltage sensing without additional sensing lines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sensing lines are additionally provided for the display panel to sense the threshold voltage of the OLED, then the threshold voltage sensing capability is improved, but the line design margin of the display panel is reduced
Solution Approach 1:
The data line is designed to perform dual functions: supplying data voltages to pixels during normal operation and sensing threshold voltages of OLEDs during sensing periods. This eliminates the need for separate sensing lines, thereby preserving the line design margin while maintaining threshold voltage sensing capability.
Solution Approach 2:
The patent merges the data line and sensing line functions into a single data line. By combining these two functions, the patent reduces the total number of lines required in the display panel, thus improving the line design margin while maintaining both data transmission and threshold voltage sensing capabilities.
2Device complexity
If a sharing structure is adopted where a plurality of horizontally adjacent pixels shares one sensing line, then the number of sensing lines is reduced, but individual detection of shared pixels becomes impossible
Solution Approach 1:
The sensing operation is segmented into pixel-unit operations. By sequentially activating switching transistors in each pixel and applying specific voltage sequences, the patent enables individual threshold voltage measurement for each pixel even though they share the same data line. This segmentation approach maintains individual detection capability while reducing the number of physical sensing lines.
Solution Approach 2:
The patent employs periodic sensing operations where each pixel is sequentially selected and measured during specific sensing periods. Through periodic activation of pixel-specific switching transistors and application of voltage sequences, individual pixel characteristics can be detected over time using a shared data line, thus achieving individual detection without requiring dedicated sensing lines for each pixel.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables accurate sensing of OLED threshold voltage without reducing the line design margin, thereby preventing luminance variations and image sticking by using data lines for both data supply and sensing, ensuring consistent image quality.
Implementation Method 1
reading out a change in the voltage of the second node, which increases depending on the driving current, through the data line
Data Source
AI summary
An electroluminescent display and a method of sensing electrical characteristics of the electroluminescent display are disclosed. The electroluminescent display includes a display panel including a plurality of pixels, a plurality of gate lines, and a plurality of data lines and a driver integrated circuit connected to the data line through a channel terminal. The driver integrated circuit includes a data voltage generator configured to generate a data voltage to be supplied to the pixel, a first switch connected between the channel terminal and the data voltage generator, a sensor configured to sense electrical characteristics of the pixel, and a second switch connected between the channel terminal and the sensor.