Projection Lens with Positive Lens Groups and Intermediate Image
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Solution Overview
Problem
Current wide-angle projectors face challenges in reducing lens length while maintaining optical quality due to excessive lens count and length, which affects price competitiveness and projector volume.
Innovation Solution
A projection lens design comprising a first, second, and third lens group with positive refractive powers, forming an intermediate image between the first and third groups, reducing the overall number of lenses and lens length, and incorporating aspheric lenses for improved optical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If an optical path is designed to form an intermediate image to reduce lens size, then the outer diameter of the lens is reduced, but the overall length of the optical system becomes larger
Solution Approach 1:
The patent transforms the optical path configuration from a linear arrangement to a folded path using reflective elements (mirrors or prisms). This allows the optical system to achieve intermediate image formation with reduced overall length by utilizing spatial folding in another dimension, effectively decoupling the optical path length from the physical device length.
Solution Approach 2:
The patent employs a compact lens group arrangement where multiple lens elements are nested or closely integrated within a reduced optical path. The first, second, and third lens groups are positioned to form intermediate images in a compact configuration, allowing the system to maintain high optical performance while minimizing the overall length of the projection lens.
2Ease of manufacture
If the number of lenses is reduced to decrease production cost, then the price competitiveness improves, but the optical quality may deteriorate
Solution Approach 1:
The patent optimizes the refractive powers and focal lengths of the remaining lens groups to compensate for the reduced number of elements. By carefully selecting and adjusting optical parameters (refractive indices, curvatures, spacing), the system maintains high optical quality with fewer lenses, thereby reducing manufacturing complexity and cost while preserving imaging performance.
Solution Approach 2:
The patent combines multiple optical functions into fewer lens groups. The first, second, and third lens groups are designed to perform both imaging and aberration correction functions that would traditionally require separate elements. This merging approach reduces the total lens count and production cost while maintaining optical quality through integrated design optimization.
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 achieves reduced lens length and maintains good optical quality under fixed focus and ultra short focus requirements, enhancing price competitiveness and projector compactness.
Implementation Method 1
The first lens group includes a plurality of lenses having refractive power. The second lens group includes at least one lens having refractive power. The third lens group includes a diaphragm, and a plurality of lenses having refractive power
Data Source
AI summary
The disclosure proposes a projection lens including a first lens group, a second lens group and a third lens group arranged in sequence along an optical axis from a magnification side to a reduction side. The first lens group includes a plurality of lenses having refractive power. The second lens group includes at least one lens having refractive power. The third lens group includes a diaphragm, and a plurality of lenses having refractive power, wherein an intermediate image is formed between the first and third lens groups, and the refractive powers of the first, second and third lens groups are positive, positive, and positive, respectively. A projection device including the above projection lens is also proposed.