Point Light Source Illumination Device With Cylindrical Lens
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Solution Overview
Problem
Conventional light sources for document reading devices, such as discharge tubes like fluorescent lamps and xenon lamps, suffer from inefficiencies in light distribution, leading to uneven illumination and re-reflection issues, which affect image reproduction and color balance, especially when switching between fixed and shifting document types.
Innovation Solution
A document reading device utilizing a point light source and a light-guiding member with a cylindrical lens structure that ensures a high illuminance distribution range coincident with the reading area, minimizing stray light and re-reflection, and using LEDs to provide uniform illumination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional discharge tube light sources (fluorescent lamps, xenon lamps) are used, then sufficient illumination intensity is provided, but uneven illuminance distribution and re-reflection occur causing poor image reproduction and color balance
Solution Approach 1:
The patent divides the illumination system into distinct functional components: a point light source, a light-guiding member with cylindrical lens structure, and positioning mechanisms. This segmentation allows each component to be optimized independently, with the cylindrical lens specifically designed to control light distribution in the sub-scanning direction while maintaining simplicity.
Solution Approach 2:
The cylindrical lens structure provides localized control over light distribution, creating a high illuminance distribution range that coincides substantially with the reading area. This local quality enhancement ensures uniform illumination precisely where needed on the document surface without affecting other areas.
2Illumination intensity
If discharge tube light sources are used, then illumination is provided, but light wastage occurs due to re-reflection and uneven distribution
Solution Approach 1:
The patent extracts and eliminates the problematic re-reflection phenomenon by using a point light source combined with a cylindrical lens structure. This configuration directs light efficiently onto the document surface without the tube wall reflections that cause energy loss in conventional discharge tube systems.
Solution Approach 2:
The invention changes the fundamental parameters of the light source from an extended discharge tube to a point source, and modifies the light distribution pattern through the cylindrical lens to create a substantially constant illuminance distribution. This parameter change transforms the illumination pattern from uneven with re-reflection to uniform and efficient.
3Adaptability or versatility
If conventional light sources are used, then illumination is provided, but color balance and image reproduction deteriorate when switching between fixed and shifting document types
Solution Approach 1:
The illumination device using a point light source and cylindrical lens structure provides universal illumination that works effectively for both fixed and shifting document types. The substantially constant illuminance distribution across the reading area ensures consistent image reproduction quality regardless of the document reading mode, eliminating the need for separate optimization for different document types.
4Manufacturing precision
If point light source with cylindrical lens is used, then uniform illuminance distribution is achieved, but device complexity increases
Solution Approach 1:
The patent employs a cylindrical lens structure that uses curvature in one dimension (the sub-scanning direction) to control light distribution. This curved optical element efficiently creates uniform illuminance distribution without requiring complex multi-element optical systems, maintaining relative simplicity while achieving the desired illumination uniformity.
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 achieves a more efficient and balanced illumination, reducing light wastage and improving image reproduction by maintaining consistent illuminance across the reading area, regardless of document type, thus enhancing the reading process.
Implementation Method 1
a light-guiding member having an incident surface opposed to a light-emitting surface of the point light source and a light-emitting surface opposed to the reading area
Data Source
AI summary
An illumination device for a reading device which irradiates light over a predetermined illumination width including a reading area having a predetermined reading width extending in a main scanning direction of a document and reads the light reflected from the document using a reading element has a point light source, and a light-guiding member having an incident surface opposed to a light-emitting surface of the point light source and a light-emitting surface opposed to the reading area. An illumination area generated by the light has a high distribution range of a substantially constant illuminance, and the high distribution range coincides substantially with the reading area.