Prism Adhesive Air Gap OFF Light Heat Management
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Solution Overview
Problem
In projection display apparatuses using digital micromirror devices (DMD), OFF light that is not used as image light can be reflected by dichroic mirror surfaces and cause heat generation, particularly when it returns to prisms in the color separator-combiner system.
Innovation Solution
An image generation unit is designed with a color separator-combiner prism system that includes an adhesive surface and an air gap between the second and third prisms. The adhesive surface is bonded over regions where image light is emitted and illumination light passes, while the air gap is formed over a region that receives OFF light reflected by a dichroic mirror surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If OFF light is directed away from image light using a color separator-combiner prism system, then image light quality is improved, but reflected OFF light causes heat generation in the prism bases
Solution Approach 1:
The interface between the second and third prisms is segmented into three distinct regions: a first region for image light emission, a second region for illumination light passage, and a third region for reflected OFF light reception. This segmentation allows each region to handle specific light types appropriately, directing reflected OFF light away from heat-generating prism bases while maintaining image light quality.
Solution Approach 2:
Different regions of the prism interface are assigned different optical properties and functions. The first region is optimized for image light emission, the second for illumination light transmission, and the third for capturing and redirecting reflected OFF light. This local differentiation enables precise control over light paths and heat management in specific areas of the prism system.
2Productivity
If dichroic mirror surfaces are used to separate colors, then color separation efficiency is improved, but OFF light reflection causes heat generation and light loss
Solution Approach 1:
The third prism is designed to receive and utilize reflected OFF light that would otherwise be wasted and cause heat generation. By capturing this reflected light in the third region and guiding it through the third prism, the system converts the harmful reflected OFF light into a controlled optical path, preventing heat generation in the prism bases while maintaining color separation efficiency.
Solution Approach 2:
The third prism acts as an intermediary element that captures reflected OFF light from the dichroic mirror surface and redirects it away from the heat-generating prism bases. This intermediary structure mediates between the color separation function of the dichroic mirrors and the heat management requirement, allowing efficient color separation while preventing energy loss as heat.
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 suppresses heat generation from reflected OFF light, even when a part of the OFF light is reflected by a dichroic mirror surface and returns to the second prism, by guiding the reflected OFF light away from the optical path and reducing unnecessary light interactions within the prism system.
Implementation Method 1
an adhesive surface and an air gap are provided between the second and third prisms, the adhesive layer being bonded over a range including a first region from which the image light is emitted and a second region through which the illumination light passes
Implementation Method 2
the air gap being formed over a range including a third region that receives, among OFF light generated by the third light modulation element, OFF light reflected by a dichroic mirror surface between the first prism and the second prism
Data Source
AI summary
An image generation unit includes: three light modulation elements of a first, a second, and a third light modulation element that modulate illumination light to generate image light; and a color separator-combiner prism that includes a first, a second, and a third prism guiding the illumination light to the first, the second, and the third light modulation element, respectively, in which between the second prism and the third prism, an adhesive surface and an air gap are provided, the adhesive surface being bonded over a range including a first region from which the image light is emitted and a second region through which the illumination light passes, the air gap being formed over a range including a third region that receives, among OFF light generated by the third light modulation element, OFF light reflected by a dichroic mirror surface between the first prism and the second prism.