Fluorescent Color Wheel Black Frame Insertion for Ghosting Reduction
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Solution Overview
Problem
The 'ghosting' phenomenon occurs in projection display products due to the response time of liquid crystal molecules and persistence of vision, causing image blur, which existing technologies have not effectively addressed despite the use of high-speed digital micromirror devices.
Innovation Solution
A fluorescent color wheel with a substrate featuring a light converting part, a light transmitting part, and a light absorbing part arranged along its circumference, integrated into a projector system with a dichroic mirror and color filter wheel to modulate light and insert a 'black' image between frames, reducing persistence of vision effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If liquid crystal molecules are used for image display, then the device can achieve image modulation, but the response time of liquid crystal molecules causes intermediate states between images, resulting in ghosting phenomenon
Solution Approach 1:
A black image insertion layer is introduced as an intermediary element between consecutive color frames. This layer temporarily blocks light transmission during the transition period, preventing the persistence of vision from blending adjacent frames and eliminating ghosting effects while maintaining the liquid crystal's image modulation capability.
2Speed
If digital micromirror device chip is used to improve response speed, then the pixel response time is reduced, but the persistence of vision in human eye still causes ghosting phenomenon
Solution Approach 1:
A black image insertion layer is placed in the optical path to preemptively counteract the persistence of vision effect. By inserting a black frame between color frames, the harmful overlapping of images perceived by the human eye is prevented, even when the DMD chip operates at high speeds.
3Illumination intensity
If the area of light converting part is increased to improve light emission, then more yellow light is generated, but the overall device complexity increases
Solution Approach 1:
The color wheel is designed with distinct regional zones: a light converting part with fluorescent material for yellow light generation, a light transmitting part for direct blue light passage, and a light absorbing part for black image insertion. Each region has optimized local properties to perform its specific function, allowing the largest area to be allocated to the light converting part for maximum yellow light emission while maintaining overall system simplicity through functional zonation.
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 reduces image blur by inserting a 'black' image between frames, minimizing the 'ghosting' phenomenon and enhancing image clarity by managing light emission and absorption efficiently.
Implementation Method 1
the light converting part comprises a fluorescent substance emitting yellow light
Data Source
AI summary
Disclosed are a fluorescent color wheel and a projector. The fluorescent color wheel includes a substrate; and a light converting part, a light transmitting part, and a light absorbing part, which are provided on one side of the substrate and arranged along the circumference of the substrate, wherein the light emitted from the light converting part can exit from said side of the substrate.