Concave Prism Air Gap Structure for Thermal-Stable Projection Optics
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Solution Overview
Problem
Conventional projection apparatuses using total internal reflection prisms suffer from thermal deformation of the air gap due to heat buildup, leading to color spots and dark spots in projected images, especially under high brightness conditions.
Innovation Solution
The optical assembly features concave optical regions on facing prism surfaces with a gradually decreasing vertical distance from the center to the edge, maintaining a consistent air gap thickness despite thermal expansion, thereby preventing interference and image defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the air gap between the two prisms is reduced to avoid interference, then the manufacturing precision is improved, but the thermal deformation causes the air gap to shrink and disappear, leading to color spots and dark spots in the projected image
Solution Approach 1:
The patent changes the geometric parameters of the prism optical regions from flat surfaces to concave surfaces with specific curvature radii. The first optical region has a first curvature radius and the second optical region has a second curvature radius, creating a controlled air gap that maintains stable spacing despite thermal expansion, thereby preventing interference patterns while ensuring manufacturing precision
Solution Approach 2:
The patent applies curvature to the optical regions of the prisms by designing concave surfaces with specific curvature radii. This spherical/curved geometry creates a controlled air gap structure that is more resistant to thermal deformation effects compared to flat surfaces, maintaining consistent spacing and preventing color spots and dark spots in the projected image
2Illumination intensity
If the brightness of the projection is increased, then the illumination intensity is improved, but the heat residue increases causing the total internal reflection prism to expand thermally and deform, leading to air gap deformation and interference
Solution Approach 1:
The patent modifies the geometric parameters of the prism surfaces by introducing concave shapes with specific curvature radii. This parameter change creates a more thermally stable air gap structure that maintains its spacing even when the prism temperature increases due to higher projection brightness, thereby preventing thermal deformation and interference patterns
Solution Approach 2:
The patent designs the concave optical regions with pre-calculated curvature radii that anticipate and compensate for thermal expansion. The curvature is designed beforehand to create sufficient air gap clearance that can accommodate thermal deformation without causing the air gap to disappear, thus cushioning against the harmful effects of temperature increase during high-brightness operation
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
Prevents color and dark spots in projected images by maintaining the air gap thickness, ensuring high-quality image projection even under increased brightness.
Implementation Method 1
the heat residue will cause a temperature difference between the inside and outside of the total internal reflection prism, which will cause the total internal reflection prism to begin to expand thermally
Implementation Method 2
the light will begin to be interfered during the process of passing through, and this phenomenon of the interference of the light will lead to color spots in the projected image
Data Source
AI summary
An optical assembly includes a first prism and a second prism. The first prism has a first surface. The first surface includes a first optical region. The second prism has a second surface. The first and the second surface are disposed facing each other. The second surface includes a second optical region, in which on a first reference plane, an orthographic projection of the first optical region overlaps an orthographic projection of the second optical region, and the first reference plane is substantially parallel to the first surface or the second surface. When the optical assembly is at a first temperature, at least one of the first optical region and the second optical region is concave, and a vertical distance between the first and the second optical region gradually decreases from a first center point of the first optical region to a first edge of the first optical region.