Display Driver Flicker Suppression via Gamma Compensation
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Solution Overview
Problem
Current gaming monitors with variable refresh rate synchronization functions experience flicker due to changes in refresh rate, which are not effectively suppressed by existing methods that delay gamma value adjustments based on frame length measurements.
Innovation Solution
A display driver and device with a common voltage generation part, reference gamma voltage generation part, gamma compensation part, and gradation voltage generating circuit that quickly adjust gradation voltages based on feedback common voltage fluctuations, ensuring consistent luminance and reducing flicker occurrence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the refresh rate is dynamically changed to synchronize with variable frame rate video sources, then the display can show smooth motion and reduce display delay, but the gamma characteristic changes cause luminance variation visible as flicker
Solution Approach 1:
The patent dynamically adjusts the gamma characteristic parameter in response to refresh rate changes. When the refresh rate is changed to synchronize with variable frame rate video, the gamma characteristic is simultaneously modified to compensate for luminance variations, thereby eliminating flicker while maintaining smooth motion display
Solution Approach 2:
The patent implements a feedback mechanism where the system detects the actual refresh rate being applied and uses this information to adjust the gamma characteristic accordingly. This closed-loop control ensures that luminance remains stable even as the refresh rate dynamically changes to match variable frame rate content
2Measurement precision
If the gamma value is changed after measuring the refresh rate for each frame, then the refresh rate can be detected, but the timing of changing the gamma value delays by at least one frame length, failing to avoid flicker
Solution Approach 1:
The patent performs preliminary measurement of the frame period during vertical blanking periods without waiting for complete frame processing. By starting the refresh rate detection early and using the measured frame period to proactively adjust the gamma characteristic before the next refresh rate change occurs, the system eliminates the one-frame delay and prevents flicker in real-time
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively suppresses flicker by quickly compensating for common voltage fluctuations, maintaining consistent display luminance even with changes in refresh rate, thereby improving the viewing experience.
Implementation Method 1
a common voltage generation part receiving a reference common voltage, generating a common voltage by amplifying the reference common voltage, and applying the common voltage to the common electrode
Implementation Method 2
a gamma compensation part taking in a voltage of the common electrode as a feedback common voltage from the display panel, and generating first to k-th compensation reference gamma voltages in which voltage values of the respective first to k-th reference gamma voltages are adjusted on the basis of a difference between the feedback common voltage and the reference common voltage
Data Source
AI summary
The present invention includes a common voltage generation part, a reference gamma voltage generation part, a gamma compensation part, a gradation voltage generating circuit, and a DA conversion part. The common voltage generation part generates a common voltage by amplifying a reference common voltage and applies the common voltage to a common electrode of a display panel. The reference gamma voltage generation part generates reference gamma voltages. The gamma compensation part takes in a voltage of the common electrode as a feedback common voltage from the display panel and generates compensation reference gamma voltages in which voltage values of the respective reference gamma voltages are adjusted on the basis of a difference between the feedback common voltage and the reference common voltage. The gradation voltage generating circuit generates gradation voltages on the basis of the compensation reference gamma voltages. The DA conversion part selects a gradation voltage corresponding to a display data piece from the gradation voltages.