Tapered Light Guide Rod for Endoscope Illumination

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Solution Overview

Problem

Existing light source optical systems for endoscopes face challenges in manufacturing a light guide with a conically shaped entrance end face, leading to low manufacturing yield and difficulty in achieving a larger entrance area compared to the exit area.

Innovation Solution

A light source optical system with a light guide rod configured such that the entrance port area is larger than the exit port area, with specific diameter and length ratios, and a taper shape that converges light efficiently, allowing for easy manufacturing and improved illumination.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If a light guide with a conically shaped entrance end face is manufactured to increase the entrance area, then the light intake capability is improved, but the manufacturing difficulty increases and manufacturing yield decreases

Engineering Contradiction:
Improveentrance area of light guideVSAvoidmanufacturing ease of light guide
Core Design Contradiction:
Area of stationary objectVSEase of manufacture

Solution Approach 1:

The patent applies parameter changes by specifying precise dimensional relationships (diameter ratios between 1.05-2.0, length-to-diameter ratios between 0.05-0.5) to optimize the tapered shape of the light guide. These parameter optimizations enable the conical entrance end face to be manufactured using conventional processes while maintaining the area enlargement benefit, thus resolving the contradiction between increased entrance area and manufacturing ease.

Inventive Principle:
Principle #35Parameter changes

2Illumination intensity

If the entrance area of the light guide is enlarged to take in more light, then the illumination brightness is improved, but the manufacturing precision requirements increase

Engineering Contradiction:
Improveillumination brightnessVSAvoidprecision of light guide diameter
Core Design Contradiction:
Illumination intensityVSManufacturing precision

Solution Approach 1:

The patent resolves this contradiction by establishing specific parameter ranges: the diameter ratio between entrance and exit ends is controlled within 1.05-2.0, and the length-to-diameter ratio is controlled within 0.05-0.5. These optimized parameters ensure that the light guide can be manufactured with conventional precision while achieving sufficient area enlargement for bright illumination.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent applies partial action by implementing a moderate taper ratio rather than an extreme conical shape. The diameter ratio is kept within 1.05-2.0, which provides sufficient area enlargement for improved illumination while remaining achievable with standard manufacturing capabilities, avoiding the need for excessive precision.

Inventive Principle:
Principle #16Partial or excessive action

3Productivity

If a tapered light guide structure is implemented to converge light, then the light distribution efficiency is improved, but the device complexity increases

Engineering Contradiction:
Improvelight distribution efficiencyVSAvoidstructural complexity of light guide
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent applies segmentation by dividing the light guide into distinct functional zones: a tapered section for light convergence and a cylindrical section for light transmission. This segmentation allows the complex light convergence function to be achieved in a localized tapered region while the majority of the light guide maintains a simple cylindrical structure, thus improving light distribution efficiency without excessively increasing overall device complexity.

Inventive Principle:
Principle #1Segmentation

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 system achieves efficient light convergence and uniform illumination, expanding the light distribution range while simplifying the manufacturing process and reducing manufacturing costs.

Implementation Method 1

a reflecting inner surface for guiding light in the light guide path

Methodology Applied
Scientific EffectTotal internal reflection: Total Internal Reflection

Implementation Method 2

a taper part having a tapered shape, in which the reflecting inner surface expands from a midway position toward an exit port side

Methodology Applied
Scientific EffectOptical convergence: Focusing

Data Source

PatentEP3273838B1Light source optical system and light source device
Publication Date: 2022.02.16 HOYA CORPORATION
  • EP3273838B1 patent drawingFigure 1
  • EP3273838B1 patent drawingFigure 2
  • EP3273838B1 patent drawingFigure 3

AI summary

A light source optical system, comprising: a collecting optical system that collects light incident thereon from a light source; and a light guide rod having an entrance port through which the collected light enters the light guide rod, an reflecting inner surface defining a light guide path, and an exit port through which the light guided in the light guide path by being totally reflected on the reflecting inner surface exits, wherein the reflecting inner surface includes a taper part formed in one of an entire region defined from the entrance port to the exit port and a part defined from a midway point between the entrance port and the exit port to the exit port, the taper part being inclined to gradually get closer to an axis line of the light guide path at a point closer to the exit port.