OLED Pixel Current Measurement via Bidirectional Data Line
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Solution Overview
Problem
Existing OLED displays face challenges with non-uniform behavior across panels and over time due to degradation, requiring additional feedback lines and transistors for compensation, which increases cost and reduces pixel density.
Innovation Solution
A method to determine the current of a pixel circuit connected to a source driver by measuring the current and converting it into a digital code, allowing for compensation without additional feedback lines, using a readout circuit integrated with the source driver to process the data for uniformity and aging adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If additional feedback lines and transistors are added to monitor pixel circuits for degradation compensation, then measurement precision and reliability improve, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent combines the monitoring function with the existing data line by making the data line bidirectional. The same physical conductor is used for both writing data to the pixel circuit and reading back monitoring information, eliminating the need for separate feedback lines and reducing overall device complexity while maintaining measurement capability
Solution Approach 2:
The data line is given multiple functions: it serves as both a data input line for programming pixel circuits and a monitoring line for reading degradation information. This multi-functionality reduces the total number of conductors needed and simplifies the overall display structure
2Measurement precision
If additional feedback lines and transistors are added for pixel monitoring, then measurement precision improves, but pixel density decreases
Solution Approach 1:
By merging the monitoring function into the existing data line infrastructure, the patent eliminates the need for additional dedicated feedback lines and transistors at each pixel. This reduces the area consumed by monitoring components and allows for higher pixel density while maintaining degradation measurement capability
3Reliability
If additional feedback lines and transistors are added for compensation, then reliability improves, but manufacturing cost increases
Solution Approach 1:
The patent merges the monitoring and compensation functions into the existing data line and pixel circuit structure. By using the bidirectional data line for both data writing and degradation monitoring, the system achieves reliable compensation without adding expensive additional components, thereby reducing manufacturing cost while maintaining reliability
Solution Approach 2:
The pixel circuit monitors its own degradation characteristics through the bidirectional data line without requiring external monitoring components. The circuit uses its existing infrastructure to perform self-diagnostics, reducing the need for additional manufacturing steps and components
Data Source
AI summary
A system and method for determining the current of a pixel circuit and an organic light emitting diode (OLED). The pixel circuit is connected to a source driver by a data line. The voltage (or current) supplied to the pixel circuit by the source driver. The current of the pixel and the OLED can be measured by a readout circuit. A value of a voltage from the measured current can be extracted and provided to a processor for further processing.