Projection Prism Layout for Redirecting OFF Light Heat
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Solution Overview
Problem
Existing projection-type video display devices face issues with thermal influence and size increase due to OFF light emitted by the image display element, leading to heat generation and difficulty in arranging cooling members, especially in high-luminance devices.
Innovation Solution
A projection-type video display device design that guides OFF light in an opposite direction to the projection lens using a reflection surface within the reflection prism, reducing thermal influence and suppressing size increase by eliminating the need for additional prisms and air layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a light absorbing member and cooling member are arranged to cover the irradiation range of OFF light, then thermal influence is reduced, but device size increases and arrangement space becomes difficult to secure
Solution Approach 1:
The patent extracts the harmful OFF light from the main optical path by using a reflection prism to redirect it in an opposite direction to the projection lens. This separates the OFF light path from the ON light path, allowing the light absorbing member to be positioned away from the projection lens area, thus reducing the thermal influence on the projection lens while avoiding significant increase in device size.
Solution Approach 2:
The reflection prism acts as an intermediary element that redirects OFF light away from the projection lens. By introducing this intermediate optical component, the system manages the thermal issue without requiring large cooling members near the projection lens, thus resolving the contradiction between thermal management and device size.
2Measurement precision
If an air layer is provided between the image display element and total reflection prism, then OFF light is reflected and contrast is improved, but the size of the prism and projection lens increases
Solution Approach 1:
Instead of using an air layer to reflect OFF light (which increases prism size), the patent inverts the approach by using a reflection prism with a specific reflective surface orientation. The reflection surface is inclined to redirect OFF light in the opposite direction to the projection lens, achieving the same contrast improvement without increasing prism dimensions.
3Measurement precision
If a high refractive index prism is used to guide OFF light, then stray light is reduced and contrast is improved, but heat generation and thermal expansion occur due to internal absorption
Solution Approach 1:
The patent converts the harmful effect of OFF light into a beneficial arrangement by redirecting it through the reflection prism. The OFF light is guided in an opposite direction to the projection lens, where it can be absorbed by a light absorbing member positioned away from the projection lens. This converts the potential harm of heat generation near the projection lens into a manageable situation where heat is dissipated away from critical components.
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 design effectively reduces thermal impact on the projection lens area, allows for smaller cooling members, and prevents image flare, maintaining reliability and reducing device size while managing heat dissipation efficiently.
Implementation Method 1
a reflection surface that guides the OFF light in an opposite direction to the projection lens with respect to an ON light emitting surface to the projection lens included in the reflection prism
Data Source
AI summary
A projection-type video display device includes a light source, an image display element, a projection lens, a reflection prism, and a reflection surface. The image display element generates ON light modulated as video light by reflecting source light from the light source at a first angle and OFF light as unnecessary light by reflecting the source light at a second angle. The projection lens projects the ON light. The reflection prism guides the source light to the image display element and guides the ON light modulated by the image display element to the projection lens. The reflection surface guides the OFF light in an opposite direction to the projection lens with respect to an ON light emitting surface to the projection lens included in the reflection prism.