Light Guide with Constricted Section for Image Reading Illumination
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Solution Overview
Problem
Existing image reading apparatuses face challenges in achieving high condensing efficiency in the sub-scanning direction due to insufficient illumination uniformity when using point light sources, as previous solutions do not effectively align and condense direct and reflected light beams.
Innovation Solution
A light guide system comprising a first part that guides light beams to a constricted section and a second part that bends and reflects them for enhanced condensing, using side parts for total reflection and a reflection condensing part to ensure efficient illumination across the sub-scanning direction, thereby improving light distribution and reducing shadows.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If point light sources are arranged along the main scanning direction, then the reading speed can be increased, but illumination unevenness occurs in the sub-scanning direction
Solution Approach 1:
The light guide is divided into multiple sections with different functions: a first light guide section for guiding light from the source, a second light guide section for bending the optical path, and a light exit section for condensing the light. This segmentation allows each section to optimize for its specific function, resolving the contradiction between speed and uniformity.
Solution Approach 2:
The invention addresses sub-scanning direction illumination issues by introducing a vertical optical path bend in the light guide. This dimensional change in light propagation allows condensing in the sub-scanning direction without affecting the main scanning direction arrangement of light sources.
2Device complexity
If light beams are directly delivered from multiple point light sources to the original surface, then the system structure is simple, but illumination unevenness and density unevenness occur in the read image
Solution Approach 1:
A light guide acts as an intermediary between the point light sources and the original surface. This mediator condenses and redistributes the light beams, transforming the direct but uneven illumination into uniform illumination while maintaining the simple point source configuration.
Solution Approach 2:
The light guide incorporates a bent optical path with curved surfaces that reflect and redirect light beams. This curvature allows the light to be condensed in the sub-scanning direction and distributed uniformly across the original surface.
3Ease of manufacture
If conventional light guides are used without condensing function, then the manufacturing is simple, but condensing efficiency in the sub-scanning direction is insufficient
Solution Approach 1:
Different sections of the light guide are assigned different optical properties: the first section has simple guiding surfaces for easy manufacture, while the second section incorporates bent surfaces with specific reflectivity for condensing, and the exit section has condensing surfaces. This local differentiation achieves high condensing efficiency while maintaining overall manufacturing simplicity.
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 proposed light guide system significantly enhances illumination uniformity and condensing efficiency in the sub-scanning direction, allowing for higher accuracy in reading glossy originals and reducing illuminance unevenness, thus supporting increased reading speeds and improved image quality.
Implementation Method 1
a first side part that totally reflects light beams traveling from the incident part in a first direction and a second side part that totally reflects light beams traveling from the incident part in a second direction
Implementation Method 2
a reflection condensing part that has a condensing function in the cross section perpendicular to the direction of arrangement of the light source, is located at a predetermined distance from the constricted part, and totally reflects light beams further diverging after passing through the constricted part
Data Source
AI summary
A light guide has first and second light guide parts (S, T) in front and rear of a constricted part (2). The first light guide has first and second side parts (1a, 1b). The second light guide part has a reflection condensing part (4) and third and fourth side parts extending from the constricted part to divert the first and second side parts more outward than imaginary surfaces (1c, 1d) as extensions of the first and second side parts beyond the constricted part.