Projector Illuminator Layout for Uniform Reflective Light Diffusion
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Solution Overview
Problem
Existing projectors using laser light sources face challenges with transmissive diffusion plates that struggle to achieve a wide diffusion angle, leading to increased backscattered light and decreased light utilization efficiency, while reflective diffusion plates result in uneven illuminance distribution and require larger downstream optical systems.
Innovation Solution
An illuminator design incorporating a light diffuser with a reflective diffusion plate that diffusively reflects combined light, rotated by a driver, and shifts the incidence position of the chief ray to align with the collimator, combined with a light collector and collimator to ensure balanced light distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a transmissive diffusion plate is used to diffuse light, then the light can be diffused, but the diffusion angle is limited and backscattered light increases, reducing light utilization efficiency
Solution Approach 1:
The patent inverts the conventional transmissive diffusion approach by using a reflective diffusion plate that diffusively reflects light rather than transmitting it. This inversion allows the diffusion plate to achieve a wider diffusion angle while maintaining high light utilization efficiency, as the reflective surface can redirect light in multiple directions without the backscattering losses associated with transmissive plates.
Solution Approach 2:
The patent changes the optical parameter of the diffusion plate from transmissive to reflective mode. By adjusting the surface properties and optical characteristics of the diffusion plate to operate in reflective mode, the system achieves both wide diffusion angle and high light utilization efficiency simultaneously.
2Loss of energy
If a reflective diffusion plate is used to achieve wide diffusion angle, then light utilization efficiency improves, but the illuminance distribution becomes uneven and downstream optical system size must increase
Solution Approach 1:
The patent introduces an asymmetric incident angle configuration where the chief ray of combined light is intentionally shifted to incident on the diffusion plate at a specific angle relative to the optical axis. This asymmetric incidence angle compensates for the uneven illuminance distribution caused by the reflective diffusion plate, creating a more uniform light distribution pattern while maintaining high light utilization efficiency.
3Illumination intensity
If the incidence position of chief ray is shifted to optimize diffusion, then illuminance distribution improves, but alignment precision requirements increase
Solution Approach 1:
The patent incorporates a light collector lens positioned between the light combining member and the diffusion plate to pre-concentrate and direct the combined light into a controlled beam path. This preliminary optical conditioning ensures that the chief ray incident on the diffusion plate is properly positioned and collimated, reducing the sensitivity to alignment variations and facilitating easier manufacturing and assembly.
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 design enhances light utilization efficiency by preventing uneven diffusion and reduces the need for larger optical components, maintaining balanced illuminance distribution and improving image quality.
Implementation Method 1
a diffusion plate having a diffusion surface that diffusively reflects the combined light
Implementation Method 2
a driver that rotates the diffusion plate around an axis of rotation that intersects with the diffusion surface
Implementation Method 3
a light collector that is provided between the light combining member and the light diffuser and directs the combined light in the form of a spot toward the light diffuser
Implementation Method 4
a collimator that parallelizes the combined light that exits out of the light diffuser
Data Source
AI summary
An illuminator includes a first light source that emits first light, a second light source that emits second light, a light combining member that combines the first light and the second light, a light diffuser that diffuses combined light, a light collector that is disposed between the light combining member and the light diffuser and directs the combined light toward the light diffuser, and a collimator that parallelizes the combined light emitted from the light diffuser. The light diffuser includes a diffusion plate having a diffusion surface that diffusively reflects the combined light, and a driver that rotates the diffusion plate. The diffusion surface inclines with respect to the optical axis of the light collector. An incidence position where the chief ray of the combined light is incident on the light collector is shifted with respect to the optical axis toward the side where the collimator is disposed.