Charging Ratio Compensator for OLED Display Voltage Accuracy
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Solution Overview
Problem
As the resolution and driving frequency of OLED devices increase, the charging time of pixels decreases, leading to a decrease in the charging ratio of the actual charging voltage to the desired target voltage, which degrades display quality.
Innovation Solution
A display device and method that includes a charging ratio compensator to sense the target and charging voltages and generate correction data voltage to adjust the reference data voltage, ensuring the difference between the target and charging voltages is equal to or less than a reference value, thereby maintaining optimal charging ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the resolution and driving frequency of OLED devices are increased, then the display quality and performance are improved, but the charging time of pixels decreases leading to degraded display quality
Solution Approach 1:
The patent applies preliminary action by performing voltage compensation before the actual display operation. The charging ratio compensator pre-calculates and stores compensation values in a lookup table based on different grayscale levels and charging times. During operation, the appropriate compensation value is retrieved and applied to the data voltage before it reaches the pixel, ensuring the pixel achieves the target voltage even with reduced charging time at high resolutions and frequencies.
Solution Approach 2:
The patent implements parameter changes by dynamically adjusting the data voltage applied to pixels based on charging time conditions. When the charging time is insufficient (as occurs at high resolutions and frequencies), the charging ratio compensator modifies the data voltage parameter using compensation values from the lookup table. This parameter adjustment ensures that the pixel voltage reaches the desired target level despite the shortened charging period.
2Speed
If the charging time is reduced to accommodate higher resolution, then the response speed is improved, but the charging ratio of actual charging voltage to target voltage decreases
Solution Approach 1:
The patent implements feedback by measuring the actual charging voltage and comparing it with the target voltage to determine the charging ratio. Based on this feedback information, the system identifies when compensation is needed and retrieves appropriate compensation values from the lookup table. The compensated voltage is then applied to correct the charging deficiency, ensuring reliable voltage delivery even when charging time is reduced for faster response.
Solution Approach 2:
The patent applies preliminary action by pre-calculating compensation values for various charging time conditions and storing them in a lookup table during manufacturing or initialization. When operation begins, the system simply retrieves the pre-computed compensation value based on the current grayscale level and charging time, rather than calculating it in real-time. This approach maintains reliability while supporting fast response speeds.
3Manufacturing precision
If a charging ratio compensator is added to sense voltages and generate correction data, then the image quality is improved, but the device complexity increases
Solution Approach 1:
The patent introduces an intermediary component - the charging ratio compensator - that sits between the data driver and the pixel array. This compensator senses the actual charging voltage, compares it with the target voltage, and generates corrected data voltages using lookup tables. By placing this intermediary at the data driver level rather than within each pixel, the solution improves image quality while minimizing the increase in overall device complexity.
Solution Approach 2:
The patent applies copying by using a lookup table that stores pre-computed compensation values for different grayscale levels and charging time conditions. Instead of performing complex real-time calculations for each pixel, the system copies the appropriate pre-stored compensation value from the lookup table based on the current operating conditions. This approach maintains high image quality while keeping the computational complexity low.
Data Source
AI summary
A display device includes a display panel having a plurality of first and second scan lines, a plurality of data lines, a plurality of sensing lines, and a plurality of pixels, a data driver to apply a reference data voltage to the data lines and change the voltage level of the reference data voltage based on a compensating data, a scan driver to apply a first scan voltage to the first scan lines and a second scan voltage to the second scan lines, a timing controller to generate control signals that control the data driver and the scan driver, and a charging ratio compensator to sense a target voltage charged in a first pixel of the plurality of pixels to which the reference data voltage is provided during a predetermined target time, sense a charging voltage charged in the first pixel to which the reference data voltage is provided during a charging time, and output the compensating data that changes a voltage level of the reference data voltage applied to the pixel during the charging time until the difference between the target voltage and the charging voltage is substantially equal to or less than a predetermined reference value.