Spherical Segment Lens Assembly for Small-Diameter Optical Units
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Solution Overview
Problem
Existing optical units in endoscopes face challenges in maintaining optical performance with small diameters due to difficulties in manufacturing and assembly of plano-convex lenses, leading to increased costs and complexity.
Innovation Solution
The optical unit employs spherical segment lenses held by a frictional force in a holding member, with lenses formed as spherical segments and polished to maintain optical performance, reducing the diameter and simplifying manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If plano-convex lenses are used in the objective optical system, then the lens structure is simple, but processing becomes more difficult as the outer diameter of each lens is reduced and manufacturing precision deteriorates
Solution Approach 1:
The patent replaces plano-convex lenses with spherical lenses that have completely curved surfaces. This spheroidality principle resolves the technical contradiction by eliminating the flat surface that causes manufacturing difficulty in small-diameter lenses. The spherical shape maintains optical simplicity while being easier to manufacture with consistent precision at small scales, as spherical surfaces can be produced with uniform curvature without the alignment issues inherent in plano-convex designs.
2Volume of moving object
If the diameter of plano-convex lenses is reduced, then the device size is reduced, but it becomes difficult to distinguish between convex and flat surfaces and accurately fix the lens to a lens holder
Solution Approach 1:
The spherical lens design with completely curved surfaces eliminates the ambiguity of distinguishing between convex and flat surfaces in small-diameter lenses. The uniform spherical geometry provides clear visual and tactile identification features, making assembly straightforward even at reduced diameters. The spherical shape naturally indicates the correct orientation and positioning without requiring differentiation between flat and curved surfaces.
Solution Approach 2:
The spherical lens design is self-identifying and self-aligning due to its uniform curvature. The lens structure itself provides the necessary identification features without requiring additional markings or complex fixation mechanisms. This self-service characteristic simplifies the assembly process by allowing operators to correctly position and identify lenses through their inherent spherical geometry alone.
3Reliability
If a biconcave lens is used to form an image surface outside the lens group, then the optical performance is improved, but manufacturing and assembly become more difficult
Solution Approach 1:
The patent employs spherical lenses with single-sided curvature instead of biconcave lenses. This spheroidality approach achieves the necessary optical performance while significantly simplifying manufacturing. The single spherical surface is easier to fabricate with consistent precision compared to the two concave surfaces of a biconcave lens, particularly at small diameters where maintaining dual surface accuracy is challenging.
4Reliability
If a relay optical system is provided between the lens and the imaging element, then the optical performance is improved, but the parts cost increases
Solution Approach 1:
The spherical lens design achieves multi-functionality by simultaneously providing image formation and adequate optical performance without requiring additional relay optical systems. The single spherical lens performs the dual function of focusing light and forming images with sufficient quality, eliminating the need for separate relay lenses or additional optical components that would increase system complexity and cost.
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 design achieves excellent optical performance with a small diameter, reducing manufacturing costs and complexity while improving assembly accuracy.
Implementation Method 1
The holding member holds the first lens and the second lens with a frictional force
Data Source
AI summary
An optical unit includes a first lens, a second lens, and a holding member. The first lens is formed in a spherical segment having a first flat surface and a first convex spherical surface. The second lens is formed in a spherical segment having a second flat surface and a second convex spherical surface. A holding member has a first end portion that surrounds the first lens and a second end portion that surrounds the second lens. The holding member holds the first lens and the second lens with a frictional force such that the first convex spherical surface and the second convex spherical surface are adjacent to each other between the first end portion and the second end portion. The first end portion is located on the same surface as the first flat surface or closer to the second lens than the first flat surface. The second end portion is located on the same surface as the second flat surface or closer to the first lens than the second flat surface.