Display Panel Controller Dynamic Refresh Rate Bias Voltage Flicker
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Solution Overview
Problem
Display devices using variable refresh rate (VRR) mode experience flicker when driven at low frequencies, causing unnatural screen switching due to luminance differences during gradation changes.
Innovation Solution
A display device with a display panel, gate driver, and controller that dynamically adjusts the refresh rate and supplies bias voltage during hold periods to minimize luminance deviations, incorporating a pixel circuit driven in sets of refresh and hold periods to reduce flicker.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by stationary object
If the display device is driven at a low refresh rate to reduce power consumption, then power consumption is reduced, but flicker and luminance differences occur during screen switching
Solution Approach 1:
The patent applies dynamics by making the refresh rate variable rather than fixed. The display device dynamically adjusts the refresh rate based on image characteristics - using low refresh rates for static images to save power, and automatically switching to high refresh rates when image changes are detected, thereby eliminating flicker while maintaining power efficiency.
Solution Approach 2:
The patent changes the refresh rate parameter from a constant value to a variable value that adapts to different operating conditions. By monitoring image change magnitude and adjusting the refresh rate accordingly, the system optimizes between power consumption and flicker prevention, using lower refresh rates when possible and higher rates when image quality is compromised.
2Reliability
If the refresh rate is increased to prevent flicker, then flicker is reduced, but power consumption increases
Solution Approach 1:
The system dynamically adjusts the refresh rate based on real-time image change detection. Instead of maintaining a constantly high refresh rate, the system uses low refresh rates during static display periods and only increases the rate when image changes occur, thereby preventing flicker during transitions while minimizing overall power consumption.
Solution Approach 2:
The patent implements periodic image change detection and refresh rate adjustment. The system periodically monitors whether the displayed image has changed significantly and only increases the refresh rate when necessary, creating a rhythm of low-power operation punctuated by high-refresh-rate periods only when image updates occur.
3Device complexity
If a constant refresh rate is used, then the display operation is simple, but screen switching appears unnatural due to luminance differences
Solution Approach 1:
The patent changes the refresh rate parameter from constant to variable based on image characteristics. By detecting image changes and adjusting the refresh rate accordingly, the system maintains natural screen switching without the unnatural luminance differences that occur with constant refresh rates, while keeping the control logic relatively simple through automated detection.
Solution Approach 2:
The system uses feedback by continuously monitoring image changes and using this information to adjust the refresh rate. The image change detection mechanism provides feedback about display content stability, which the controller uses to determine whether to maintain a low refresh rate or switch to a high refresh rate, thereby ensuring natural screen transitions.
Data Source
AI summary
A display device according to the embodiment of the present disclosure includes: a display panel that includes a display area where a plurality of pixels is disposed and a non-display area disposed around the display area; a gate driver that provides a scan signal and an emission control signal to the display panel; and a controller that drives the display panel in accordance with a refresh rate. The plurality of pixels includes a light emitting element and a pixel circuit that drives the light emitting element. The pixel circuit is driven in sets including at least one refresh period and at least one hold period in low frequency driving. The controller controls dynamically the refresh rate during the at least one set when a gradation of an image changes, and simultaneously, changes and supplies a bias voltage during the at least one hold period.