Compact Projection Lens with Reflector and Split Groups
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Solution Overview
Problem
The challenge is to reduce the size of projection lenses in image display devices while maintaining optical performance, as existing designs struggle to achieve a compact form without compromising image quality.
Innovation Solution
The proposed solution involves a projection lens configuration with a first lens group having negative refractive power, a reflector to bend optical paths, and a second lens group with positive and negative refractive powers on either side of an aperture stop, satisfying specific conditional formulas to optimize size and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a reflector is disposed within the lens system to bend optical paths, then the size of the projection optical system is reduced, but the lens thickness and complexity increase
Solution Approach 1:
The lens system is divided into multiple lens groups (first, second, third, fourth, and fifth lens groups) with different refractive powers. Each group performs a specific function in the optical path, allowing the system to achieve compact size through strategic placement and bending of optical paths using a reflector while maintaining manageable complexity through functional segmentation.
Solution Approach 2:
A reflector is introduced to bend the optical paths within the lens system, effectively utilizing three-dimensional space to fold the optical path. This allows the projection optical system to achieve a reduced overall size by routing light through a more complex spatial arrangement rather than a simple linear configuration.
2Reliability
If multiple lens groups with different refractive powers are arranged in sequence, then optical performance is improved and aberrations are minimized, but the device complexity increases
Solution Approach 1:
Different lens groups are assigned specific refractive powers (positive or negative) based on their position in the optical path. The first lens group has negative refractive power, while the second, third, and fourth lens groups have positive refractive power, and the fifth lens group has negative refractive power. This localized optimization of optical properties at different positions enables effective aberration correction while maintaining a structured, manageable system architecture.
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
This configuration allows for a compact projection lens that maintains high optical performance, reduces lens thickness, and minimizes aberrations, enabling smaller image display devices without sacrificing image quality.
Implementation Method 1
a reflector to bend an optical path
Implementation Method 2
a first lens group having a negative refractive power, a second lens group having a positive refractive power
Data Source
AI summary
A projection lens includes, in order from a magnification side to a reduction side, a first lens group having a negative refractive power, a reflector to bend an optical path, a second lens group having a positive refractive power, and an aperture stop disposed within the second lens group. The second lens group has a positive refractive power on the magnification side of the aperture stop, and a negative refractive power on the reduction side of the aperture stop. Conditional formula (A) is satisfied: (A) Ot/Y′<6.1, where Ot is a distance along the optical axis between a maximum-magnification-side surface of the first lens group and a surface of a lens adjacent to a reduction-side surface of the reflector, and Y′ is a maximum height of the image displayed on the display surface of the image display element.