Projection System with Telecentric Lens Group for Compact Wide-Angle Design
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Solution Overview
Problem
Existing projection systems face challenges in achieving a compact, wide-angle optical design with a large maximum half angle of view while maintaining a smaller radial dimension, as the lens closest to the enlargement side is often larger than the largest image height, leading to increased size and reduced image formation performance.
Innovation Solution
A projection system with a first lens group having positive power and a second lens group with a telecentric portion at the reduction side, arranged from the enlargement side to the reduction side, satisfying specific conditional expressions to optimize the optical design and reduce the size of the lens closest to the enlargement side.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If a wide-angle projection system is designed with a large maximum half angle of view (ω>40°), then the angle of view is improved, but the lens size closest to the enlargement side becomes larger than the largest image height, increasing the radial dimension
Solution Approach 1:
The patent applies parameter changes by modifying the optical configuration parameters: setting the first lens group with positive power and the second lens group with negative power, and positioning the aperture stop between them. This parameter change allows the lens size to be reduced while maintaining the wide angle of view requirement
Solution Approach 2:
The patent introduces a new dimensional constraint by specifying that the telecentric portion must be located at the reduction side of the projection system. This dimensional arrangement allows light rays to travel parallel to the optical axis in the telecentric region, enabling compact lens sizing while achieving wide-angle projection
2Area of stationary object
If the lens closest to the enlargement side is made smaller than the largest image height, then the radial dimension is reduced, but it becomes difficult to achieve both wide-angle projection and compact size simultaneously
Solution Approach 1:
The patent introduces the aperture stop as an intermediary element positioned between the first positive lens group and the second negative lens group. This intermediary component controls the light path and enables the system to achieve both compact lens sizing and wide-angle projection performance by limiting the cone angle of light rays
Solution Approach 2:
The patent segments the projection system into two distinct lens groups with opposite power signs: a first lens group with positive power and a second lens group with negative power. This segmentation allows each group to perform specialized functions, with the positive group providing convergence and the negative group providing divergence, enabling compact wide-angle design
3Manufacturing precision
If a telecentric portion is provided at the reduction side, then image formation performance is improved, but the optical system complexity increases
Solution Approach 1:
The patent merges the telecentric function into the existing second lens group configuration rather than adding a separate telecentric correction module. By designing the second negative lens group to inherently provide the telecentric portion at its reduction side, the patent achieves improved image formation performance while minimizing additional optical complexity
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 solution enables a wide-angle projection system with a smaller lens size closest to the enlargement side, enhancing image formation performance and suppressing aberrations, while maintaining a sufficient back focal length and correcting chromatic aberration.
Implementation Method 1
a first lens group (31) having positive power, and an aperture stop (41), and a second lens group (32) having positive power sequentially arranged from an enlargement side toward a reduction side
Implementation Method 2
A portion at the reduction side of a reduction-side lens that forms the second lens group and is located at a position closest to the reduction side is a telecentric portion
Data Source
AI summary
A projection system includes a first lens group having positive power, an aperture stop, and a second lens group having positive power sequentially arranged from the enlargement side toward the reduction side. The portion at the reduction side of a reduction-side lens that forms the second lens group and is located at a position closest to the reduction side is a telecentric portion. The projection system satisfies Conditional Expressions (1) and (2) below,ω>40° (1)YL1/YIM<6.0 (2)where ω represents a maximum half angle of view of the overall projection system, YIM represents the distance from an optical axis to the largest image height of the projection image formed at an image formation device, and YL1 is the distance from the optical axis to a chief beam corresponding to the maximum image height in an imaginary plane.