Light Source Device Thermal Expansion Compensation

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Solution Overview

Problem

Conventional light source devices for image scanning devices face challenges in maintaining uniform illumination characteristics due to temperature-dependent changes, leading to variations in light output as components expand or contract, complicating the structure and affecting illumination quality.

Innovation Solution

A light source device design that incorporates a light guide with a reflective cover and heat transfer elements, where the light guide is held in place by end holders and a housing with specific grooves and pins to minimize thermal expansion effects, ensuring consistent illumination and heat dissipation across the lengthwise direction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional light source devices are used without thermal expansion countermeasures, then the structure remains simple, but illumination characteristics vary due to temperature-dependent changes

Engineering Contradiction:
Improveillumination characteristic stabilityVSAvoidstructure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies thermal expansion compensation by providing a groove in the housing that allows the light guide to expand and contract along its lengthwise direction in response to temperature changes. The light guide holder positioned within the groove moves accordingly, maintaining proper alignment and illumination characteristics without requiring complex active compensation mechanisms

Inventive Principle:
Principle #37Thermal expansion

Solution Approach 2:

The light guide holder acts as an intermediary component between the light guide and the housing. It is positioned in the groove and facilitates the thermal expansion movement while maintaining the light guide's positional relationship with other components, thereby compensating for thermal effects through a simple mechanical intermediary

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If thermal expansion countermeasures are added to maintain illumination stability, then illumination characteristic stability improves, but device complexity increases

Engineering Contradiction:
Improveillumination characteristic stabilityVSAvoidstructure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies thermal expansion compensation by providing a groove in the housing that allows the light guide to expand and contract along its lengthwise direction in response to temperature changes. The light guide holder positioned within the groove moves accordingly, maintaining proper alignment and illumination characteristics without requiring complex active compensation mechanisms

Inventive Principle:
Principle #37Thermal expansion

Solution Approach 2:

The light guide holder acts as an intermediary component between the light guide and the housing. It is positioned in the groove and facilitates the thermal expansion movement while maintaining the light guide's positional relationship with other components, thereby compensating for thermal effects through a simple mechanical intermediary

Inventive Principle:
Principle #24Intermediary (Mediator)

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 effectively minimizes temperature-dependent changes in illumination characteristics, maintaining consistent light output and heat dissipation, thereby improving the reliability and efficiency of the light source device.

Implementation Method 1

a light guide (4) whose ends are curved, into which light from the light-emitting element (91, 93) is input from the ends

Methodology Applied
Scientific EffectTotal internal reflection: Total Internal Reflection

Implementation Method 2

heat transfer bodies (18, 19) that transfer heat from the light-emitting elements (91, 93)

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 3

heat-sink fins (71, 72) that dissipate heat

Methodology Applied
Scientific EffectConvection: Convection

Implementation Method 4

heat-sink fins (71, 72) that dissipate heat

Methodology Applied
Scientific EffectThermal radiation: Thermal Radiation

Data Source

PatentEP2813754B1Light-source device
Publication Date: 2020.01.22 MITSUBISHI ELECTRIC CORP
  • EP2813754B1 patent drawingFigure 1~2
  • EP2813754B1 patent drawingFigure 3~4
  • EP2813754B1 patent drawingFigure 5A~5B

AI summary

In the present disclosure, temperature-dependent changes in the illumination characteristics of a light source device are minimized. The light source device is provided with the following: a light-emitting part (3); a light guide (4) having in the center a columnar part whose central axis direction is a lengthwise direction, that guides light input into an end face from the light-emitting part (3) in a lengthwise direction of the columnar part, and outputs light from a side face of the columnar part; a light guide holder (5) that covers an end of the light guide (4) except for at least part of the end face; and a support part (7), having a through-hole that penetrates from one face to another face formed therein, that holds an end of the light guide holder (5) on a side of a first opening on the one face of the through-hole so as to allow sliding in the lengthwise direction, or alternatively, the end of the light guide holder (5) stretches in the lengthwise direction inside the first opening or above the first opening, and light from the light-emitting part (3) is input into the light guide via a second opening on the other face of the through-hole, or alternatively, the light-emitting part (3) is disposed in the second opening, and the support part (7) supports an optical filter (6) between the first opening and the second opening while maintaining a designated spacing with the light-emitting part (3).