Light Guide Thermal Expansion Management in Original Reading Apparatus
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Original reading apparatuses experience issues with fogging and shininess due to heat-induced expansion of light guides, which affect image quality, especially when reading thick originals.
Innovation Solution
The apparatus includes a light guide with boss portions that engage with a base member, allowing for adjustment and fixation to prevent warping, using a metallic plate member for heat dissipation and a light-transmissive plastic guide to correct warping, ensuring consistent light distribution and reducing image defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the light guide is fixed rigidly to prevent warping, then image quality is improved, but thermal expansion is restricted causing stress and potential damage
Solution Approach 1:
The light guide is designed with flexible attachment mechanisms including elastic members and resilient portions that allow the light guide to expand and contract with thermal changes while maintaining optical performance. The elastic member compresses when the light guide expands due to heat, preventing stress concentration and potential damage while keeping the light guide stable during reading operations.
Solution Approach 2:
The patent employs materials and structures with different thermal expansion characteristics. The base member has lower thermal expansion than the light guide, and elastic members are selected with specific elasticity to accommodate expansion. This parameter differentiation allows the system to handle thermal expansion dynamically without compromising image quality or structural integrity.
2Reliability
If the light guide is allowed to expand freely with heat, then stress is reduced, but warping occurs causing fogging and shininess in images
Solution Approach 1:
The elastic member is pre-compressed or pre-positioned to counteract the expected thermal expansion of the light guide. When heat causes expansion, the elastic member's predetermined elasticity provides resistance that prevents warping and maintains the light guide's positional stability, thereby preventing fogging and shininess in the captured images.
Solution Approach 2:
The resilient portion of the light guide structure is designed to flex and deform elastically in response to thermal expansion, absorbing dimensional changes without causing warping. This flexibility allows the light guide to accommodate heat-induced expansion while maintaining optical alignment and preventing image defects.
3Ease of manufacture
If the attachment structure is simplified for ease of manufacture, then production cost is reduced, but stability of light guide position deteriorates
Solution Approach 1:
The attachment structure is divided into modular components: a base member with positioning holes, a light guide with corresponding positioning protrusions, and elastic members. This segmentation allows each component to be manufactured independently using simple processes, yet when assembled, they provide stable positioning and thermal expansion accommodation through the coordinated action of multiple simple elements.
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 effectively suppresses fogging and shininess by maintaining a stable light guide position, ensuring accurate image reproduction and reducing the occurrence of image defects during the reading process.
Implementation Method 1
A light guide has a first boss portion and second boss portions that engage with a base member, and is configured to guide light emitted from the plurality of light-emitting elements toward the original
Implementation Method 2
A photoelectric conversion element is configured to convert reflected light from the original illuminated by the illumination unit into an electrical signal
Implementation Method 3
using a metallic plate member for heat dissipation and a light-transmissive plastic guide to correct warping
Data Source
AI summary
A light guide includes a plurality of boss portions. A round hole portion is provided near the center of a base member for fixing the light guide, and slit portions are provided on both ends thereof. The round hole portion supports one boss portion in both the longitudinal direction and the lateral direction of the light guide. The slit portions support boss portions in the lateral direction of the light guide, but are free in the longitudinal direction of the light guide. That is, the center of the light guide is fixed from both directions, and thus both ends of the light guides can expand away in the longitudinal direction. This cuts the influence of expansion by half.