Zoom Lens Intermediate Image Compact Wide Angle View
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing zoom lenses for projection display devices have limitations in achieving a wide angle of view with a small size and simple configuration, as they often require a long back focal length and complex optical systems to correct aberrations and accommodate high zoom ratios.
Innovation Solution
A zoom lens design that forms an intermediate image, comprising a first optical system on the magnification side and a second optical system on the reduction side, with two movable and two stationary lens groups, where one stationary group has positive refractive power, allowing for adjustable spacings between adjacent groups to achieve a wide angle of view while maintaining a compact size and simplifying the optical configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a zoom lens uses a long back focal length to avoid thermal problems and accommodate a color synthesis prism, then thermal issues are resolved and color synthesis is enabled, but the overall lens size increases and the angle of view is limited
Solution Approach 1:
The zoom lens is divided into multiple lens groups (first through fourth lens groups) with different functions. The first lens group handles wide-angle imaging, the second lens group provides telecentricity for color synthesis, the third lens group corrects aberrations, and the fourth lens group fine-tunes the optical path. This segmentation allows each group to be optimized for its specific function, enabling a compact overall design while maintaining the required back focal length for thermal management and color synthesis prism accommodation.
2Manufacturing precision
If a zoom lens is designed to be telecentric on the reduction side to accommodate spectral characteristics of the color synthesizing prism, then color accuracy is improved, but the entrance pupil position must be at a sufficiently far distance, increasing lens complexity
Solution Approach 1:
The telecentric function is extracted and assigned to a specific lens group (the second lens group) rather than requiring the entire zoom lens system to be telecentric. This second lens group is positioned to create an exit pupil at infinity on the reduction side, which satisfies the color synthesis requirement while allowing other parts of the system to be optimized for compactness and ease of manufacturing.
3Adaptability or versatility
If a zoom lens increases the angle of view by shortening focal length, then the angle of view widens, but the magnification side lens diameter becomes excessively large
Solution Approach 1:
The patent uses an intermediate image formation approach where the first lens group forms an intermediate image, which is then relayed by subsequent lens groups to the final image plane. This intermediate imaging stage allows the wide-angle first lens group to have a smaller diameter, while the later lens groups can be positioned to efficiently relay the light without requiring excessively large diameters, effectively managing the dimensional constraints across different optical planes.
4Volume of moving object
If a relay system forms an intermediate image to shorten back focal length and decrease magnification side lens diameter, then compactness is improved, but the configuration becomes more complex compared to normal zoom lenses
Solution Approach 1:
Each lens group in the four-group system is designed to perform multiple functions simultaneously. For example, the first lens group provides both wide-angle imaging and begins the intermediate image formation, while the second lens group provides both telecentricity and relay functions. This multi-functionality reduces the need for additional specialized components, keeping the overall configuration relatively simple despite the intermediate image formation approach.
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 a wide angle of view with a small size and simple configuration, effectively correcting aberrations and reducing lens diameter, while maintaining telecentricity and minimizing fluctuations during zooming.
Implementation Method 1
The second optical system includes two movable lens groups, which move by changing spacings between the groups adjacent to each other in a direction of an optical axis during zooming, and two stationary lens groups which remain stationary with respect to the reduction side imaging plane during zooming. In addition, one stationary lens group of the two stationary lens groups is disposed to be closest to the reduction side, and has a positive refractive power.
Data Source
AI summary
Provided are a zoom lens, a projection display device including the zoom lens, and an imaging apparatus including the zoom lens. The zoom lens forms an intermediate image at a position conjugate to a reduction side imaging plane and forms the intermediate image again on a magnification side imaging plane. The zoom lens includes: a first optical system on the magnification side; and a second optical system on the reduction side. The intermediate image is formed between the magnification side and the reduction side. The second optical system includes two movable lens groups, which move by changing spacings between the groups adjacent to each other in a direction of an optical axis during zooming, and two stationary lens groups which remain stationary with respect to the reduction side imaging plane during zooming. One stationary lens group is disposed to be closest to the reduction side, and has a positive refractive power.