OLED Compensation Circuit Using Line Calibration Factors
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Solution Overview
Problem
Display devices with organic light emitting diodes (OLEDs) face image quality deterioration due to degraded driving transistors and threshold voltage deviations, which can lead to compensation errors caused by parasitic capacitance variations in receiving lines during external compensation.
Innovation Solution
A compensation circuit that includes sensing data generating circuits, a calibration factor generator, and a calibration operation portion to measure and compensate for the characteristics of driving transistors, using line calibration factors to adjust data voltages and remove noise, thereby preventing compensation errors from parasitic capacitance deviations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If external compensation is performed using measured values from receiving lines, then driving transistor degradation and threshold voltage deviations are compensated, but compensation errors occur due to parasitic capacitance deviations in the receiving lines
Solution Approach 1:
The patent introduces a calibration factor as an intermediary element that mediates between the raw measured values from receiving lines and the final compensation result. This calibration factor, derived from reference pixel measurements, corrects the measurements to eliminate parasitic capacitance errors without requiring changes to the fundamental measurement process
Solution Approach 2:
The patent changes the measurement parameters by introducing calibration factors that adjust the measured threshold voltage values. By applying these calibration factors, the system transforms inaccurate raw measurements into accurate compensated values, effectively changing the parameter space from which compensation is performed
2Reliability
If receiving lines are used to measure current for threshold voltage compensation, then driving transistor characteristics are compensated, but image quality deteriorates due to compensation errors from parasitic capacitance variations
Solution Approach 1:
The calibration factor serves as an intermediary that corrects the relationship between receiving line measurements and actual transistor characteristics. By introducing this mediator, the system maintains reliable transistor compensation while eliminating image quality deterioration caused by parasitic capacitance variations
Solution Approach 2:
The patent implements a feedback mechanism where reference pixels are measured to generate calibration factors, which are then applied to correct measurements from display pixels. This feedback loop ensures that compensation accurately reflects actual transistor characteristics rather than being distorted by parasitic capacitance
Data Source
AI summary
A display device according to an exemplary embodiment of the present inventive concept includes: pixels; scan lines extending in a row direction and connected to the pixels; a data lines extending in a column direction and connected to the pixels; a receiving lines extending in the column direction and connected to the pixels; and a compensation circuit portion that generates first sensing data by receiving a current flowing to the pixels through the receiving lines, and generates a compensation value that compensates a characteristic of a driving transistor included in each of the pixels by multiplying the first sensing data by a calibration factor that corresponds to a position of each of the pixels, wherein the calibration factor includes a line calibration factors that correspond to the receiving lines.