Endoscope Illumination Device Reducing Vignetting
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Solution Overview
Problem
Endoscopes for the large intestine often have limited rear field of view due to their design, making it cumbersome to observe areas behind folds, and existing illumination systems suffer from vignetting, which exacerbates the visibility of bright and dark areas.
Innovation Solution
An illumination device with a diffusion optical member and a reflective layer that diffuses and reflects light to reduce the angular range of the emission region as distance increases, alleviating vignetting and improving illumination uniformity, and an endoscope design with a wide-angle imaging system to enhance viewability without bending.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a conventional illumination system is used in the endoscope, then the structure is simple, but vignetting occurs causing noticeable difference between bright and dark parts
Solution Approach 1:
A diffusion optical member is introduced as an intermediary component between the light source and the observation target. This diffusion optical member includes a light-emitting section that receives light from the light source and a light-emitting surface that faces the observation target, with a reflective layer on its radial inner surface. The diffusion optical member diffuses the light in the radial direction while reducing emission angle in the axial direction, thereby achieving uniform illumination without causing vignetting, while maintaining relatively simple device structure.
Solution Approach 2:
The emission angle of light is changed as a parameter to resolve the contradiction. Specifically, the diffusion optical member is designed to reduce the emission angle in the axial direction while maintaining light diffusion in the radial direction. This parameter change allows the light to illuminate the observation target uniformly without being blocked by the insertion portion structure, thus achieving both good illumination uniformity and simple device structure.
2Area of stationary object
If the angle of view is limited to 180 degrees or less, then the imaging optical system is simple, but the rear field of view cannot be observed
Solution Approach 1:
The imaging function is segmented into multiple independent imaging optical systems. Instead of using a single complex optical system to achieve wide-angle viewing, the patent employs multiple imaging optical systems arranged around the insertion portion axis. Each imaging optical system captures light from a specific direction, and their combined fields of view cover 360 degrees or more, including both forward and rear fields of view. This segmentation approach achieves wide field of view while keeping each individual imaging optical system relatively simple.
Solution Approach 2:
The field of view is expanded from a single-direction linear arrangement to a three-dimensional circumferential arrangement. Multiple imaging optical systems are positioned at different angular positions around the insertion portion axis, creating a spatial distribution that captures light from all directions. This dimensional change from one-dimensional to three-dimensional arrangement enables observation of the entire circumference including rear areas without requiring a single complex wide-angle optical system.
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 allows for improved observation of rear fields without bending the endoscope and reduces the noticeable difference between bright and dark areas by optimizing light distribution, enhancing both the illumination efficiency and uniformity.
Implementation Method 1
a diffusion optical member that is disposed around a predetermined axis in the circumferential direction, that is provided with an incident end disposed so as to be opposed to the emission end, that guides the illumination light entering from the incident end while diffusing the illumination light
Implementation Method 2
a reflective layer that is disposed adjacent to a radially inward surface of the diffusion optical member and that reflects the illumination light radially outward
Data Source
AI summary
For the purpose of performing illumination with which vignetting of illumination light caused by a structure is alleviated, thus making the difference between a bright part and a dark part on an object less noticeable, an illumination device according to the present invention is provided with: a light-emitting part that has an emission end from which illumination light is emitted; a diffusion optical member that is disposed around a predetermined axis in the circumferential direction, that is provided with an incident end disposed so as to be opposed to the emission end, that guides the illumination light entering from the incident end while diffusing the illumination light, and that emits the illumination light from a surface thereof; and a reflective layer that is disposed adjacent to a radially inward surface of the diffusion optical member and that reflects the illumination light radially outward, wherein an angle, around the axis, of an emission region for the illumination light in the diffusion optical member is reduced as the distance from the incident end is increased in the axial direction.