OLED Data Driver Sensing Circuit for Pixel Current Compensation
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Solution Overview
Problem
In OLED displays, variations in driving current due to fabrication process instability, device parameter drifting, and transistor aging lead to non-uniformity across subpixels, necessitating improved pixel compensation methods.
Innovation Solution
A data driving integrated circuit with digital-to-analog and analog-to-digital converters, sensing switches, and reference voltage lines, coupled with a pixel compensation method that includes stages like sensing voltage write-in, charging, and data write-back to stabilize the driving current across subpixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If pixel compensation is implemented to compensate for driving current variations, then display uniformity is improved, but device complexity increases due to additional sensing circuits and compensation mechanisms
Solution Approach 1:
The patent combines the sensing transistor and switching transistor into a single pixel electrode structure, allowing dual functionality within a compact design. The sensing transistor senses voltage at the pixel electrode while the switching transistor controls signal writing, both integrated within the same pixel structure to reduce overall device complexity while maintaining compensation capability
Solution Approach 2:
The pixel electrode serves multiple functions: it acts as both the sensing node for voltage measurement and the switching node for data signal writing. This multi-functional design eliminates the need for separate dedicated sensing and switching structures, reducing device complexity while achieving both sensing and compensation functions
2Device complexity
If sensing lines are shared among multiple columns of pixel driving circuits, then device complexity is reduced, but measurement precision deteriorates due to potential signal interference
Solution Approach 1:
The patent implements time-division multiplexing where sensing operations and data writing operations are performed in alternating time periods. During the sensing period, sensing transistors are activated to read voltage values, while during the data writing period, switching transistors are activated to write data signals. This periodic separation prevents signal interference on shared sensing lines while reducing the number of dedicated lines needed
Solution Approach 2:
The patent employs a feedback mechanism where sensed voltage values from the pixel electrodes are read through the shared sensing lines, converted to digital values, and used to generate compensated data signals. The sensing operation provides feedback information about the actual pixel electrode voltage, which is then used to correct for threshold voltage shifts and ensure accurate display uniformity
Data Source
AI summary
A data driving integrated circuit includes a digital-to-analog converter configured to receive a respective digital data signal from a timing controller and convert the respective digital data signal to a respective analog data signal, which is output to a display panel through a respective data line; an analog-to-digital converter configured to receive a respective analog sensing signal from a respective sensing line in the display panel and convert respective analog sensing signal to a respective digital sensing signal, which is output to the timing controller; a first sensing switch configured to control a connection between a first reference voltage line and the respective sensing line; a second sensing switch configured to control a connection between a second reference voltage line and the respective sensing line; and a third sensing switch configured to control the connection between the analog-to-digital converter and the respective sensing line.