Reference Pixel Sensing for Accurate Display Compensation Voltage
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Solution Overview
Problem
Display devices with uniformly manufactured pixels exhibit varying driving characteristics, leading to inconsistent luminance and low reliability of compensation voltages due to differences in mobility and threshold voltage.
Innovation Solution
A display device with a reference pixel measurer that calculates error functions based on threshold voltage differences to generate accurate compensation voltages, improving the accuracy of active pixel driving by using a reference driving transistor with a double-gate structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If pixels are manufactured by the same process, then manufacturing precision is improved, but driving characteristics (mobility and threshold voltage) vary due to process limitations
Solution Approach 1:
The patent implements a feedback mechanism by measuring the actual driving characteristics (threshold voltage and mobility) of each pixel through sensing operations, then using this measured data to calculate and apply compensation voltages. This closed-loop feedback approach corrects the variations in driving characteristics that arise from manufacturing process limitations, thereby improving luminance consistency across all pixels.
Solution Approach 2:
The patent changes the electrical parameters (threshold voltage and mobility) of individual pixels through compensation voltages applied during the driving process. By dynamically adjusting these parameters based on measured characteristics, the system compensates for manufacturing variations and achieves consistent luminance output across pixels that were manufactured with slight parameter deviations.
2Measurement precision
If conventional sensing operations are performed, then some compensation data is obtained, but the compensation voltage has low reliability due to insufficient accuracy
Solution Approach 1:
The patent performs preliminary sensing operations during blank periods before the actual display refresh, measuring threshold voltages and mobility values in advance. This preliminary measurement allows the system to pre-calculate compensation voltages that are then applied during the subsequent display period, improving the reliability of compensation by ensuring accurate measurements are obtained under controlled conditions before they are needed.
Solution Approach 2:
The patent performs multiple sensing operations at different data voltages (first, second, and third reference data voltages) rather than a single measurement. This excessive measurement approach provides multiple data points that can be used to calculate more accurate threshold voltages and mobility values, thereby improving the reliability of the compensation voltage beyond what a single conventional sensing operation could achieve.
3Measurement precision
If multiple sensing operations are performed at different data voltages, then measurement precision is improved, but loss of time increases due to additional operations
Solution Approach 1:
The patent performs multiple sensing operations at different reference data voltages during the blank period, which occurs periodically between display frames. By utilizing this periodic blank period for comprehensive measurements, the system achieves high measurement precision through multiple data points without interfering with the normal display refresh cycle, thus minimizing the time penalty for enhanced measurements.
Data Source
AI summary
A display device includes a display panel including an active pixel and a reference pixel, a reference pixel measurer which applies a reference data voltage and a gate voltage to the reference pixel, calculates a first threshold voltage and a second threshold voltage based on a driving current of the reference pixel and calculates a difference between the first threshold voltage and the second threshold voltage, and a driving controller which controls the reference pixel measurer and outputs a data signal based on the difference.