Electroluminescent Display Driving Device Threshold Voltage Sensing
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Solution Overview
Problem
In electroluminescent display apparatuses, the threshold voltage of driving elements shifts over time, leading to variations in driving current between pixels, which causes luminance non-uniformity and degrades image quality.
Innovation Solution
A driving device and method that selects a representative pixel line based on accumulation stress, performs pre-sensing on the representative pixel line, and uses over driving control (ODC) signals to shorten the sensing time of threshold voltage, enhancing compensation performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional threshold voltage sensing is performed on all pixel lines, then compensation accuracy is maintained, but sensing time becomes excessively long
Solution Approach 1:
The patent segments the sensing process into two distinct phases: (1) pre-sensing on a representative pixel line to determine ODC control signals, and (2) selective sensing on all pixel lines based on the ODC control signals. This segmentation allows the system to maintain compensation accuracy while significantly reducing overall sensing time by avoiding redundant sensing operations on all pixel lines.
Solution Approach 2:
The patent performs preliminary sensing on a representative pixel line before sensing all other pixel lines. The ODC control signals generated from this preliminary action are then used to optimize the subsequent sensing process, allowing the system to anticipate and prepare for the sensing requirements of all pixel lines, thereby reducing total sensing time while maintaining accuracy.
2Reliability
If threshold voltage sensing is performed frequently to improve compensation performance, then image quality improves, but driving time and power consumption increase
Solution Approach 1:
The patent divides the sensing operation into selective segments based on ODC control signals rather than uniformly sensing all pixel lines. This allows frequent compensation updates to be performed only where needed (on pixel lines with significant threshold voltage shifts), maintaining high compensation performance while reducing overall driving time and power consumption.
Solution Approach 2:
The patent applies different sensing strategies to different pixel lines based on local characteristics revealed by the representative pixel line sensing. The ODC control signals enable the system to apply high-frequency sensing only to pixel lines requiring compensation while using lower-frequency or no sensing on other lines, optimizing the balance between compensation performance and driving time.
Data Source
AI summary
A driving device of an electroluminescent display apparatus, including a display panel where a pixel line including a set of pixels is provided in plurality, includes a pixel line determiner configured to select a representative pixel line, disposed at a position at which an accumulation stress caused by repetitive display of an input image is largest, from among all pixel lines, an over driving control controller configured to select a sample pixel characteristic value from among pixel characteristic values of the representative pixel line and selectively output a first ODC control signal and a second ODC control signal, based on a magnitude of the sample pixel characteristic value, and a sensing and driving circuit configured to pre-sense pixel characteristic values of the representative pixel line in the first sensing period, perform ODC sensing on the pixel characteristic values of the all pixel lines once each according to the first ODC control signal in a second sensing period succeeding the first sensing period, and perform the ODC sensing on the pixel characteristic values of the all pixel lines a plurality of times each according to the second ODC control signal in the second sensing period, wherein a sensing data voltage supplied to each pixel of the all pixel lines has multi-voltage levels, in the second sensing period for the ODC sensing.