Image Sensor Light Guide Offset for Uniform Illumination
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Solution Overview
Problem
Existing image sensor units with multiple light guides experience nonuniform light intensity distribution due to supporting members, leading to broken similarity of output when the object distance changes, causing local light intensity changes and increased nonuniformity.
Innovation Solution
The image sensor unit design includes rod-like light guides with pressing portions that are offset in the longitudinal direction, allowing the centers of pressing portions on one light guide to be deviated from those on another, ensuring uniform light distribution and maintaining output similarity even when the object distance changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If supporting members are provided to assemble light guides to the housing, then the light guides are fixed and assembled properly, but the intensity of light emitted to the object becomes locally changed and the distribution in the longitudinal direction becomes nonuniform
Solution Approach 1:
The pressing portions that cause harmful light blocking are extracted and repositioned. Instead of being located at the same position on all light guides, they are positioned at different longitudinal locations on different light guides, thereby removing the harmful effect of synchronized light blocking while preserving the necessary light guide fixation function
Solution Approach 2:
The arrangement of pressing portions is made asymmetric across different light guides. While each light guide has pressing portions at regular intervals, the longitudinal positions of these pressing portions are staggered between different light guides, creating an asymmetric pattern that prevents simultaneous light blocking at any given longitudinal position
2Ease of manufacture
If the positions of pressing portions on all light guides are the same in the longitudinal direction, then the structure is simple and easy to manufacture, but the nonuniformity in light intensity distribution becomes large
Solution Approach 1:
The pressing portions are arranged in an asymmetric pattern where the longitudinal positions differ between light guides. This maintains manufacturing simplicity through regular spacing on each guide while achieving uniform light distribution through the staggered arrangement across guides
Solution Approach 2:
Each light guide has pressing portions at different longitudinal locations, creating local variations in the arrangement. This local differentiation ensures that at any given longitudinal position, not all light guides have pressing portions simultaneously, thereby maintaining light intensity uniformity
3Reliability
If supporting members cover the surfaces of light guides closer to the object, then the light guides are securely held, but the intensity of light is locally changed and output similarity is broken when distance changes
Solution Approach 1:
The harmful effect of pressing portions blocking light is extracted by positioning them at staggered longitudinal locations on different light guides. This removes the synchronized light blocking effect that would otherwise cause local intensity changes and output nonuniformity when the object distance changes
Solution Approach 2:
The pressing portions are pre-positioned at optimized longitudinal locations on each light guide before assembly. This preliminary positioning ensures that during operation, the pressing portions do not simultaneously block light from reaching the object, thereby pre-preventing output nonuniformity and maintaining similarity across different distances
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 reduces local light intensity changes and maintains uniform output distribution across the image sensor unit, preventing nonuniformity and breaking of output similarity when the object is displaced.
Implementation Method 1
light guides that shape light emitted by the light sources into a line and that emit the linear light elongated in a longitudinal direction to the object to be read
Implementation Method 2
an image sensor IC array photoelectrically converts the light
Data Source
AI summary
An image sensor unit includes: multiple first light guides that shape light emitted by light sources into a line and emit linear light elongated in longitudinal direction to an object to be read (P); multiple holding members that hold each of the first light guides on a frame; and an image sensor that detects light from the object to be read (P). The multiple first light guides are parallel, and in a range in which the image sensor detects the light from the object to be read (P) in the longitudinal direction of the first light guides, center positions in the main-scan direction of the multiple holding members that hold one first light guide of the multiple light guides and center positions in the main-scan direction of the multiple holding members that hold another light guide different from the one first light guide deviate from each other.