Projection Lens Layout for Uniform Upper-Edge Brightness
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Solution Overview
Problem
Existing projection-type image display apparatuses experience a decrease in brightness at the upper periphery of the final image due to the design of the optical system, which affects the overall image quality.
Innovation Solution
A lens design with a first transmissive surface, a reflective surface, and a second transmissive surface arranged coaxially, where the reflective surface is concave and the second transmissive surface is convex, forming a coaxial optical system with an inclined pupil relative to the vertical axis, ensuring that the light rays are distributed more evenly across the image plane.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a conventional optical system with a perpendicular aperture stop is used, then the optical system is simple and easy to manufacture, but the brightness at the upper periphery of the final image decreases
Solution Approach 1:
The aperture stop is designed with an inclined opening relative to the optical axis, creating an asymmetric light path configuration. This asymmetric design allows light rays from the upper periphery to pass through the aperture stop more effectively, increasing brightness at the upper periphery of the final image while maintaining a relatively simple optical system structure
Solution Approach 2:
The aperture stop opening is oriented in a direction inclined at a specific angle (e.g., 45 degrees) relative to the optical axis, introducing a dimensional change in the light path configuration. This dimensional adjustment allows light rays to reach the upper periphery of the image plane more effectively, improving brightness distribution without significantly increasing system complexity
2Quantity of substance
If the aperture stop opening is made larger to increase light throughput, then more light reaches the image plane, but the pupil becomes larger and causes aberrations
Solution Approach 1:
The aperture stop is designed with a specific inclination angle (e.g., 45 degrees) relative to the optical axis, changing the geometric parameters of the light path. This parameter change allows the aperture stop to effectively control light rays at different field angles, increasing light throughput to the upper periphery while maintaining acceptable aberration levels through optimized geometric configuration
Solution Approach 2:
The inclined aperture stop provides different light control characteristics for different regions of the image plane. The upper periphery receives enhanced light throughput due to the inclined configuration, while the center region maintains normal light control, creating localized quality improvement without compromising overall image quality
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 lens design effectively suppresses the decrease in brightness at the upper periphery of the image, maintaining consistent light distribution and improving image quality by ensuring that the divergence angle of light rays reaching different parts of the image is more uniform, thereby enhancing the overall brightness and resolution.
Implementation Method 1
a reflective surface (12) having a concave shape
Implementation Method 2
a first transmissive surface (11), a reflective surface (12), and a second transmissive surface (13) sequentially arranged
Data Source
Figure 1
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Figure 3
AI summary
A lens has a first transmissive surface, a reflective surface, and a second transmissive surface sequentially arranged from a demagnifying side toward a magnifying side. The first transmissive surface and the reflective surface are located at the lower side of an imaginary axis extending in an axis-Z direction, and the second transmissive surface is located at the upper side of the imaginary axis. The reflective surface has a concave shape, and the second transmissive surface has a convex shape protruding toward the magnifying side. An imaginary line that connects an upper intersection to a lower intersection inclines with respect to an imaginary vertical line perpendicular to the imaginary axis in a plane YZ.