Sink Device Variable Frame Rate Flicker Control
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Solution Overview
Problem
Liquid crystal display devices experience flicker due to deviations in average luminance between panel driving frames when the frame rate of the panel driving frame is changed, leading to perceivable image quality issues.
Innovation Solution
A sink device adjusts the common voltage applied to the display panel during each frame, resetting it to a reference voltage level at the starting point of each panel driving frame and adjusting it over time to minimize luminance deviations, while keeping the active period of the panel driving frame constant and changing the vertical blank period to synchronize with the image frame rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the frame rate of the panel driving frame is changed to synchronize with the image frame rate, then image quality issues such as tearing and stuttering are prevented, but flicker occurs due to luminance deviation between frames
Solution Approach 1:
The patent changes the voltage parameter (common voltage level) in response to frame rate changes. When the frame rate is adjusted, the common voltage is dynamically modified to compensate for luminance deviations, thereby preventing flicker while maintaining synchronized frame rates
Solution Approach 2:
The system implements a feedback mechanism where luminance deviations detected during frame rate changes trigger automatic voltage adjustments. The common voltage is modified based on the actual luminance performance, creating a closed-loop control that eliminates flicker
2Speed
If the vertical blank period is adjusted to change the panel driving frame rate, then synchronization with image frame rate is achieved, but average luminance deviates between frames
Solution Approach 1:
The patent modifies the common voltage parameter in direct response to vertical blank period adjustments. When the vertical blank period is changed to achieve desired frame rates, the common voltage is simultaneously adjusted to maintain consistent average luminance across frames
3Use of energy by moving object
If the frame rate is reduced for slow moving scenes to conserve power, then energy consumption decreases, but image quality consistency may be compromised
Solution Approach 1:
The system dynamically adjusts the common voltage based on real-time frame rate conditions. During low frame rate operation for power savings, the voltage is modified to maintain proper luminance levels, ensuring image quality consistency across varying operating conditions
Solution Approach 2:
The common voltage parameter is dynamically changed in response to frame rate reductions. This parameter adjustment compensates for the effects of lower frame rates, maintaining image quality consistency while allowing power consumption to decrease during slow moving scenes
Data Source
AI summary
A liquid crystal display device includes a source device that outputs image data and a sink device that performs a displaying operation based on the image data. The source device changes a frame rate of an image frame composing the image data while the displaying operation is performed. The sink device changes a frame rate of a panel driving frame for the displaying operation by adjusting a vertical blank period of the panel driving frame as the frame rate of the image frame is changed. Here, the sink device adjusts a common voltage applied to a display panel included in the sink device during a display operation of an individual frame, in accordance with the frame rate of the panel driving frame.