Projector Flicker Prevention via PWM and Phosphor Rotation Synchronization
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Solution Overview
Problem
In projectors with solid-state light sources, flickers caused by PWM control and rotating phosphor plate interference degrade image display quality, leading to visible flicker issues.
Innovation Solution
A projector configuration where the PWM control frequency of the solid-state light source and the rotation frequency of the rotating phosphor plate are synchronized or related in specific ways to prevent low-frequency flicker visibility, using a rotating phosphor plate with a phosphor material that converts blue light into red and green light, and precise control of light emission and rotation speeds to minimize interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PWM control is applied to the solid-state light source to prevent visual flicker, then high-frequency flicker is eliminated, but interference with the rotating phosphor plate produces visible low-frequency flicker
Solution Approach 1:
The patent changes the PWM control frequency parameter to be an integer multiple of the phosphor plate rotation frequency. This parameter adjustment ensures that the high-frequency PWM flicker and the rotation-induced flicker are synchronized, preventing the generation of visible low-frequency interference patterns while maintaining effective flicker suppression.
2Duration of action of stationary object
If the phosphor plate rotation speed is increased to prevent damage from light emission, then material degradation is reduced, but flicker interference with the light modulating device increases
Solution Approach 1:
The patent optimizes the rotation frequency parameter of the phosphor plate to achieve a balance between material protection and flicker prevention. By setting the rotation frequency and its relationship with the light modulating device driving frequency, the system maintains adequate material durability while minimizing visible flicker interference.
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 configuration effectively prevents visible flicker, enhancing image display quality by ensuring that the flicker components are either synchronized or differ by a controlled amount, thus eliminating low-frequency flicker interference.
Implementation Method 1
a rotating phosphor plate 13 having a phosphor material 13b, converts blue light from the solid-state light source 11 into red light and green light
Data Source
Figure 1
Figure 2A~2B
Figure 3A~3B
AI summary
There is provided a projector that can prevent a flicker from being caused by rotation of a rotating phosphor plate. The projector includes a solid-state light source that emits excitation light, a rotating phosphor plate that converts the excitation light into phosphor light, a liquid-crystal light modulating device that modulates the light from the rotating phosphor plate, a projection optical system that projects the modulated light onto a screen, and a control device that controls the solid-state light source and the rotating phosphor plate so as to satisfy any one of a conditional expression A = B, a conditional expression A = 2B, and a conditional expression |A-B| is greater than or equal to 20 and |A-2B| is greater than or equal to 20, where A represents a pulse width modulation control frequency in hertz of the solid-state light source and B represents a rotation frequency in hertz of the rotating phosphor plate.