Projector Light Source Prism Scanning With Maintained Beam Parallelism
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Solution Overview
Problem
Existing light source devices for projectors using polygon mirrors suffer from degradation of image quality due to impaired light parallelism, leading to issues such as luminance loss, contrast reduction, and color unevenness.
Innovation Solution
A light source device utilizing two rotatable transmissive optical parts, each with a quadrangular prism shape, to maintain light parallelism by rotating these parts on perpendicular axes, ensuring the light beam remains parallel to the optical axis during scanning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a polygon mirror is used to scan light across the liquid crystal light valve, then the light can be directed to illuminate the entire area, but the parallelism of the light is impaired causing divergence
Solution Approach 1:
The patent replaces the polygon mirror (mechanical reflection system) with a transmissive optical system consisting of a lens and a rotating polygonal prism. This substitution allows light to pass through the optical elements rather than reflect off a rotating mirror surface, thereby maintaining light parallelism while achieving scanning coverage across the liquid crystal light valve.
Solution Approach 2:
The patent changes the optical parameters by using a transmissive lens system with specific focal lengths and a rotating prism with controlled angular velocity. By adjusting these parameters, the system achieves both full area illumination and maintains light parallelism, resolving the contradiction between coverage area and beam quality.
2Speed
If the incident angle of light with respect to the polygon mirror reflecting surface changes temporally, then scanning is achieved, but light parallelism deteriorates leading to luminance and contrast degradation
Solution Approach 1:
The patent replaces the reflecting polygon mirror system with a transmissive optical system using a lens and rotating prism. This substitution eliminates the incident angle variation problem inherent in reflection-based scanning, allowing high-speed scanning to be performed while maintaining constant light parallelism and thus preserving luminance and contrast quality.
3Area of stationary object
If a rotating polygon mirror is used for light scanning, then the liquid crystal light valve can be illuminated across the full area, but color unevenness occurs due to impaired light parallelism
Solution Approach 1:
The patent replaces the rotating polygon mirror with a transmissive optical system comprising a lens and a rotating polygonal prism. This substitution ensures that light maintains its parallelism throughout the scanning process, thereby achieving uniform color distribution across the entire illuminated area of the liquid crystal light valve without the color unevenness caused by beam divergence.
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 maintains light parallelism, preventing luminance and contrast degradation, and color unevenness, thereby enhancing image quality in projectors.
Implementation Method 1
a first transmissive optical part which is formed of a light transmissive member rotatably supported, and which has a first plane of incidence which the first light beam L1 emitted from the first light emitter 11 enters, and a first exit surface for emitting the first light beam L1 entering the first transmissive optical part 13 through the first plane of incidence; the first transmissive optical part 13 is made rotatable centering on a first rotational axis C1 extending along a second direction Y perpendicular to a first direction X in which the optical axis AX of the first light emitter 11 extends, the first plane of incidence and the first exit surface are parallel to each other
Data Source
Figure 1~2A
Figure 2B~2E
Figure 2F~3
AI summary
A light source device according to the present disclosure includes a first light emitter for emitting a first light beam, a first optical part having a first plane of incidence which the first light beam enters, and a first exit surface from which the first light beam is emitted, and a second optical part having a second plane of incidence which the first light beam emitted from the first optical part enters, and a second exit surface from which the first light beam is emitted. The first optical part rotates centering on a first rotational axis a. The second optical part rotates centering on a second rotational axis. The first plane of incidence and the first exit surface are parallel to each other, and the second plane of incidence and the second exit surface are parallel to each other.