Light Guide Member Thermal Expansion Compensation
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Solution Overview
Problem
Existing light emitting devices face issues with the inclination of light-emitting elements due to temperature-induced changes in the length of light-guide members, leading to misalignment and reduced reading accuracy in image reading devices.
Innovation Solution
A light emitting device design that includes a light-guide member capable of expanding and contracting, a movable rigid board for mounting the light emitting element, and a pressing member that maintains contact with the light-guide member's end surface, ensuring consistent alignment and light emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the light-guide member is fixed rigidly to the housing, then the structural stability is improved, but the light-emitting element becomes misaligned with the light-guide member due to thermal expansion differences
Solution Approach 1:
The rigid board is designed to be movable in the longitudinal direction relative to the housing, allowing it to dynamically adjust its position as the light-guide member expands or contracts thermally. This dynamic adjustment maintains the alignment between the light-emitting element and the light-guide member throughout temperature variations, resolving the contradiction between structural stability and alignment precision.
2Object-affected harmful factors
If the light-guide member is allowed to expand and contract freely, then the thermal stress is reduced, but the alignment between the light-emitting element and the light-guide member deteriorates
Solution Approach 1:
The pressing member acts as an intermediary between the housing and the rigid board, applying a controlled pressing force that maintains contact between the light-emitting element and the light-guide member. This intermediary mechanism allows the light-guide member to expand and contract freely while preventing misalignment, thus reducing thermal stress without sacrificing alignment precision.
3Ease of manufacture
If the rigid board is fixed to the housing, then the ease of manufacture is improved, but the reading accuracy deteriorates due to misalignment from thermal expansion
Solution Approach 1:
The rigid board is designed with movability in the longitudinal direction, enabling it to automatically adjust its position in response to thermal expansion of the light-guide member. This dynamic design maintains accurate alignment for high reading accuracy while requiring only simple assembly operations, thus resolving the contradiction between ease of manufacture and measurement precision.
4Reliability
If the light-emitting element is pressed firmly against the light-guide member, then the light emission efficiency is improved, but the device complexity increases due to additional pressing mechanisms
Solution Approach 1:
The pressing member is designed to perform multiple functions: it applies pressing force to maintain good light emission contact, allows thermal expansion movement, and maintains alignment between components. This multi-functional design achieves reliable light emission stability without significantly increasing device complexity, as a single component accomplishes what would otherwise require multiple separate mechanisms.
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 configuration maintains the alignment of light emitting elements with the light-guide members across varying temperatures, ensuring stable light emission and improved reading accuracy in image reading devices.
Implementation Method 1
there is a case where the length of the light-guide member in one direction changes due to, for example, temperature changes
Data Source
AI summary
A light emitting device includes at least one light-guide member that extends in one direction and that is fixed to a housing in such a manner as to be capable of expanding and contracting in the one direction, at least one light emitting element that is disposed in such a manner as to face an end surface of the light-guide member and that radiates light onto the end surface of the light-guide member, a rigid board that is disposed such that the light emitting element is interposed between the rigid board and the light-guide member and on which the light emitting element is mounted, the rigid board being movable in the one direction with respect to the housing, and a pressing member that presses the light emitting element against the end surface of the light-guide member via the rigid board.