Phosphor Wheel Synchronization via Light Intensity Feedback
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Solution Overview
Problem
Conventional video display devices face challenges in synchronizing the rotation of a color wheel with the driving of a light valve with high accuracy, particularly when using a phosphor wheel, leading to potential color mixing and reduced video quality.
Innovation Solution
A video display device and method that includes a light source, a rotating substrate with a phosphor wheel having distinct regions for emitting different colors, a light detection unit to measure the intensity of emitted light, and a control section that synchronizes the rotation of the phosphor wheel and the light valve based on detected light intensity, ensuring accurate synchronization even when the index mark is displaced.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a sampling period spans two color regions of a color wheel to detect index mark displacement, then the detection method can be implemented, but synchronization accuracy deteriorates due to color mixing and light intensity variations
Solution Approach 1:
The first period is divided into a second period and a third period that do not overlap. By detecting light intensity in these separate periods and using their difference, the system avoids the color mixing problem that occurs when sampling spans two color regions, thereby maintaining high synchronization accuracy while implementing the detection method
Solution Approach 2:
The control section uses the detected light intensity difference between the second and third periods to calculate displacement amount, and then adjusts the wheel or light valve timing based on this feedback. This closed-loop feedback mechanism compensates for index mark displacement and maintains accurate synchronization
2Manufacturing precision
If the index mark position is displaced on the wheel, then manufacturing variations occur, but synchronization accuracy deteriorates due to mismatch between wheel rotation and light valve driving
Solution Approach 1:
The system detects the actual light intensity in the second and third periods, calculates the displacement amount based on the difference, and uses this feedback information to adjust the timing of the wheel or light valve. This compensates for index mark displacement caused by manufacturing variations and maintains accurate synchronization
Solution Approach 2:
The control section changes the timing parameters of the wheel rotation or light valve driving based on the detected displacement amount. By adjusting these parameters dynamically, the system compensates for fixed manufacturing errors in index mark position and achieves accurate synchronization
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
This approach allows for high-accuracy synchronization of the phosphor wheel and light valve, preventing color mixing and maintaining video quality by adjusting the index value to align the rotation and driving phases, thereby improving the overall performance of the video display device.
Implementation Method 1
a wheel having a first region which allows receiving light from the light source and emitting the light as first color light
Implementation Method 2
a light detection unit which detects intensity of the first color light emitted from the wheel
Data Source
AI summary
A video display device includes a light source, a rotating substrate, a light detection unit, a light valve, and a control section. The light detection unit detects intensity of first color light emitted from the wheel in a second period included in a first period and in a third period which is included in the first period and does not overlap with the second period, where the first period is a period equal to time during which light continuously enters a first region. The control section controls at least one of the wheel and the light valve based on the intensity of the first color light detected in the light detection unit.