Zigzag Elliptic Arc Reflector for Uniform LED Illumination
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Solution Overview
Problem
Existing image reading apparatuses face challenges in achieving uniform illumination due to the non-uniform illumination distribution caused by light-emitting devices with high directivity and the limitations of increasing light-emitting device density, leading to uneven brightness in the read images.
Innovation Solution
The proposed solution involves an illumination apparatus with a light source module comprising LEDs arranged in a line and a reflection member with a zigzag-shaped mirror surface along an elliptic arc, which converges light beams to provide uniform illumination across the reading range, ensuring high illumination uniformity even with shifts in the sheet position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If light-emitting devices with high directivity (LEDs united with lenses) are used, then illumination intensity is improved, but illumination uniformity deteriorates due to wave-shaped distribution
Solution Approach 1:
The patent applies local quality by varying the interval between light-emitting devices according to their position. Specifically, devices at positions where illumination would naturally be stronger (closer to the optical axis) are spaced farther apart, while devices at positions where illumination would be weaker (near the edges) are spaced closer together. This compensates for the inherent non-uniformity caused by high-directivity LEDs and achieves uniform illumination distribution across the entire sheet surface.
Solution Approach 2:
The patent changes the parameter of light-emitting device interval (spacing) to optimize illumination uniformity. By adjusting the spacing parameter based on position - wider spacing near the center and narrower spacing near the edges - the system compensates for the bell-shaped illumination pattern of individual high-directivity LEDs, transforming the overall distribution from wave-shaped to uniform.
2Area of stationary object
If light-emitting devices with low directivity (LEDs without lenses) are used, then illumination area is improved, but illumination uniformity deteriorates with center-bright edge-dim pattern
Solution Approach 1:
The patent applies local quality by implementing position-dependent spacing of light-emitting devices. Devices positioned to illuminate the center region (where illumination would be excessive) are spaced farther apart, while devices positioned to illuminate the edge regions (where illumination would be insufficient) are spaced closer together. This creates a compensated distribution that achieves uniform illumination across the entire wide illumination area.
3Manufacturing precision
If density of light-emitting devices around the edge is increased to prevent illumination decrease, then illumination uniformity is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent changes the spacing parameter of light-emitting devices based on position, creating a non-uniform distribution pattern that is simpler to implement than increasing edge density. The interval between devices varies continuously or in steps from the optical axis outward, providing a graceful and manufacturable solution that achieves uniform illumination without requiring complex high-density edge arrangements.
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 achieves high illumination uniformity across the reading range, maintaining a brightness variation of less than 10% even with ±1.5 mm shifts, thereby stabilizing image quality and processing speed.
Implementation Method 1
a reflection member with a zigzag-shaped mirror surface along an elliptic arc, which converges light beams
Implementation Method 2
illumination modules which have a light source using light emitting diodes (hereinafter simply referred to as LEDs)
Data Source
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AI summary
According to one embodiment, an illumination apparatus including, a first light source module which includes a light-emitting module that emits light, the light-emitting module having a line shape, and a first reflection member which includes a first reflection surface that reflects the light emitted from the light-emitting module of the first light source module for a predetermined range, wherein the first reflection surface has a cross section that has a zigzag line shape including a plurality of line segments running along a standard oval, which has a major axis that forms a predetermined angle with a direction perpendicular to the predetermined range, in a direction perpendicular to a longitudinal direction of the light-emitting module of the first light source module.