Partial Scanning Mode for High Refresh Rate Displays
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Solution Overview
Problem
Designing electronic displays that maintain high resolution and operate effectively at both normal and high refresh rates is challenging due to issues with display uniformity and visible artifacts caused by low scan time in high refresh rate modes.
Innovation Solution
The implementation of a display system that can operate in both normal and partial scanning modes, where every row is scanned in normal mode and only a subset of rows in partial mode, with gate driver circuitry including a shift register with multiple inputs to adjust scanning based on mode, allowing for higher refresh rates in partial mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the display operates at high refresh rate with every row scanned in each frame (normal scanning mode), then display uniformity and image quality are maintained, but the refresh rate is limited and cannot achieve high refresh rates
Solution Approach 1:
The display is divided into multiple sections (e.g., first section and second section) with different scanning strategies. During normal refresh rate operation, all sections are scanned; during high refresh rate operation, only selected sections are scanned. This segmentation allows the system to achieve high refresh rates for critical portions while maintaining acceptable overall display performance.
Solution Approach 2:
Different portions of the display are assigned different quality levels based on their importance. Critical display regions maintain full scanning for uniformity, while less critical regions can use partial scanning to enable higher refresh rates. This local differentiation resolves the contradiction by applying different scanning strategies to different spatial locations.
2Productivity
If the display scans only a subset of rows in each frame (partial scanning mode), then higher refresh rates are achieved, but display uniformity deteriorates and visible artifacts appear
Solution Approach 1:
The display dynamically switches between normal scanning mode and partial scanning mode based on operational requirements. The system can adaptively select the appropriate scanning strategy for different refresh rate demands, allowing high refresh rates when needed while maintaining uniformity when possible. This dynamic adaptation resolves the contradiction by making the scanning behavior flexible rather than fixed.
Solution Approach 2:
Instead of scanning all rows every frame (excessive action for high refresh rate), the system performs partial scanning of selected sections. This partial action achieves the necessary refresh rate improvement while minimizing the degradation of display uniformity by focusing scanning resources on critical display regions.
3Productivity
If the scan time per row is reduced to achieve high refresh rate, then refresh rate increases, but the low scan time causes poor display uniformity and visible artifacts
Solution Approach 1:
The display is segmented into multiple sections that can be scanned with different time allocations. By dividing the display into sections and selectively scanning them, the system can provide adequate scan time to critical sections while achieving high overall refresh rates. This segmentation prevents the uniformity degradation that would result from uniformly reducing scan time across the entire display.
Solution Approach 2:
The scanning parameters (which sections to scan, how many rows per section) are changed dynamically based on the desired refresh rate. When high refresh rate is needed, the system changes parameters to scan fewer sections with reduced scan time, accepting uniformity trade-offs in non-critical areas while maintaining performance in critical areas.
Data Source
AI summary
An electronic device may include a display such as a light-emitting diode display. The electronic device may be a head-mounted device that provides a virtual reality or augmented reality environment to a user. To reduce artifacts in the display, a display may be operable in both a normal scanning mode and a partial scanning mode. In the normal scanning mode, every row of the display may be scanned in each frame. In the partial scanning mode, only a subset of the rows of the display may be scanned in each frame. The display may have a higher refresh rate in the partial scanning mode than in the normal scanning mode. The gate driver circuitry may include a shift register that includes a plurality of register circuits. At least one register circuit may have a first input and a second input that is different than the first input.