Display Device Voltage Compensation Across Variable Refresh Rates
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Solution Overview
Problem
Display devices operating in variable refresh rate (VRR) mode experience brightness variations due to frequency changes, leading to issues like image distortion and flicker when pixels are driven at low frequencies.
Innovation Solution
A display device with a frequency calculator to determine the driving frequency of previous frames, a compensation data calculator to adjust data based on frequency comparisons, and an image data output unit to provide compensation data to the data driver, stabilizing pixel brightness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If pixels are driven at low frequency to lower refresh rate, then power consumption is reduced and life is extended, but voltage discharge causes brightness difference and image quality degradation
Solution Approach 1:
The patent applies preliminary action by calculating compensation data in advance based on the previous frame's driving frequency before the actual display occurs. When low driving frequency is detected, compensation data is pre-calculated to counteract the voltage discharge effect, ensuring brightness uniformity is maintained even when pixels are driven at low frequencies for power saving.
2Reliability
If variable refresh rate mode is implemented to improve image quality, then image quality is improved, but brightness variation occurs due to frequency changes
Solution Approach 1:
The patent implements feedback by continuously monitoring the driving frequency of previous frames and using this information to calculate appropriate compensation data. The system feeds back the frequency information through the frequency calculator and uses it to adjust the pixel voltages via compensation data, creating a closed-loop control system that maintains brightness uniformity across varying refresh rates.
Data Source
AI summary
Discussed is a display device including a display panel on which pixels are arranged, a controller configured to control the pixels in a first driving frequency in a first frame and to control the pixels in a second driving frequency in a second frame, and a data driver configured to convert an image data output from the controller to generate a data voltage and to output the data voltage to the pixels through data lines. The first frame and the second frame each include an active period and a blank period, and the data driver configured to output a first gray data voltage determined in response to the first driving frequency and the second driving frequency to the data lines during the blank period.