Endoscope Curved Window Thermal Expansion Management

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Solution Overview

Problem

Existing endoscopes with curved windows face challenges in maintaining hermetic insulation and mechanical integrity due to thermal expansion issues during autoclaving, leading to potential fissures or fractures, as conventional joining techniques fail to manage the stresses effectively.

Innovation Solution

The solution involves dividing the joining seam into two hermetically insulated seams, using a material with a closely matched thermal expansion coefficient for the interior body to the window, such as sapphire, and employing a mantle with a biocompatible material, along with a pivotable mechanism for varying the angle of vision, ensuring reliable moisture prevention and mechanical stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If conventional joining techniques are used to connect the window with the housing or mantle, then the window can be mechanically connected, but thermal expansion differences during autoclaving cause mechanical tensions that lead to fissures or fractures

Engineering Contradiction:

Improvemechanical connection strengthVSAvoidhermetic insulation reliability

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The joining seam is divided into two separate hermetically insulated seams: a first seam between the window and the interior body, and a second seam between the interior body and the mantle. This segmentation allows each seam to be optimized independently for its specific function, with the first seam focusing on thermal expansion compatibility and the second seam focusing on hermetic insulation.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

An interior body made of a material with thermal expansion characteristics intermediate between the window material and the mantle material is introduced as a mediator. This interior body acts as a buffer that accommodates thermal expansion differences, reducing mechanical tensions in both joining seams during autoclaving cycles.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If a curved window is used to achieve a wide angle of vision, then the viewing angle is improved, but the curvature and surface area increase thermal expansion stresses during joining and autoclaving

Engineering Contradiction:

Improveangle of visionVSAvoidwindow mechanical integrity

Core Design Contradiction:

Adaptability or versatilityVSStrength

Solution Approach 1:

The joining structure is segmented into multiple components (window, interior body, mantle) connected by separate seams, distributing the thermal stress across multiple junctions rather than concentrating it at a single curved interface.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The material selection for the interior body is based on matching thermal expansion parameters. By carefully selecting a material with thermal expansion characteristics intermediate between the window and mantle, the system accommodates the additional stresses introduced by the curved window geometry.

Inventive Principle:

Principle #35Parameter changes

3Manufacturing precision

If the window material is selected for optical properties, then the viewing quality is improved, but the thermal expansion coefficient mismatch with the housing or mantle causes joining and autoclaving problems

Engineering Contradiction:

Improveoptical qualityVSAvoidjoining process difficulty

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The interior body serves as an intermediary component between the optically optimized window and the housing or mantle. This mediator allows the window material to be selected purely for optical properties without compromise, while the interior body's material properties bridge the thermal expansion gap.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The system is segmented so that the window can be optimized for optical performance independently, while the interior body handles the thermal expansion compatibility requirements. This separation of concerns allows each component to be optimized for its primary function.

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

This approach allows for a variable view endoscope with a curved window to maintain hermetic insulation and mechanical integrity even after multiple autoclaving cycles, preventing damage and ensuring biocompatibility, thus enhancing the endoscope's reliability and longevity.

Implementation Method 1

the temperatures and temperature changes and resulting variable length-wise extension with conventional material pairings in a joining process as well as in a customary autoclaving process require mechanical tensions that, after a brief time, lead to fissures or fractures

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentUS9888834B2Endoscope with a window and process to manufacture an endoscope

Publication Date: 2018.02.13 KARL STORZ SE & CO KG

AI summary

An endoscope includes a window on a distal end of the endoscope, an interior body with a first material on the distal end, and a mantle with a second material on the distal end, such that the window and the interior body are joined.