Display Device Driving Transistor Compensation via Test Line
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Solution Overview
Problem
Conventional organic EL display technologies face challenges in accurately measuring and compensating for the uneven characteristics of driving transistors and organic EL elements, leading to luminance inconsistencies across pixels, especially due to initial variations and temporal changes, which are not effectively addressed by current compensation methods.
Innovation Solution
The implementation of a display device with a simple pixel circuit configuration that includes a first transistor, a switching element, and a luminescence element, along with a test current generation circuit and voltage detection unit, allowing for accurate voltage measurement and correction of data voltages to address uneven characteristics of both driving transistors and organic EL elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If complex pixel circuits are used for compensation, then luminance unevenness can be compensated, but manufacturing yield is reduced
Solution Approach 1:
The patent extracts the compensation function from complex pixel circuits and implements it through a separate test mode that measures transistor characteristics. The test line is used to measure the current through the driving transistor, and the measured data is stored and used for compensation calculations, eliminating the need for complex compensation circuits within each pixel.
Solution Approach 2:
The patent introduces a test line as an intermediary component to measure the characteristics of the driving transistor. This test line acts as a mediator between the data line and the driving transistor, allowing current measurement without requiring complex circuit modifications. The measured characteristics are then used to calculate compensation values for luminance uniformity.
2Manufacturing precision
If feedback compensation using representative pixels or sum of currents is used, then overall luminance can be compensated, but per-pixel uneven characteristic cannot be compensated
Solution Approach 1:
The patent segments the compensation approach by measuring the characteristics of each individual pixel's driving transistor separately through the test line. Instead of using overall feedback from representative pixels or sum of currents, the system performs localized measurements at each pixel, storing the measured data and using it for individual pixel compensation calculations.
3Productivity
If simple pixel circuits are used, then manufacturing yield is improved, but accurate detection of uneven characteristic for each pixel becomes difficult
Solution Approach 1:
The patent introduces a test line as an intermediary component that enables accurate measurement of driving transistor characteristics without adding complexity to the main pixel circuit. The test line allows current measurement through the driving transistor by providing a dedicated measurement path, thus maintaining simple pixel circuits while achieving precise per-pixel characteristic detection.
4Measurement precision
If voltage measurement method is used instead of current measurement, then measurement accuracy is improved, but additional measurement circuits are required
Solution Approach 1:
The patent uses the test line as an intermediary to enable voltage measurement of the driving transistor characteristics. By providing a dedicated measurement path through the test line, the system can measure voltage without requiring complex measurement circuits. The test line acts as a bridge that allows accurate voltage measurement while maintaining circuit simplicity.
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
This approach enables highly accurate detection and correction of luminance unevenness by measuring characteristic variations in both driving transistors and organic EL elements, improving the overall luminance consistency and extending the lifespan of the display device.
Implementation Method 1
a luminescence element which emits light in response to current flow from the first transistor
Data Source
AI summary
An electronic device is described. The device includes a substrate for a luminescence panel that includes data lines and pixels in which a luminescence element can be formed. Each pixel includes a driving transistor that converts a signal voltage from a data line into a signal current, and a first switch between the data line and the gate of the driving transistor. The device includes a first circuit to flow a test current from the data line through the driving transistor, a second circuit to generate a voltage on the data line corresponding to a gate voltage on the driving transistor generated by the test current, and a voltage detector to detect the voltage in the data line.