Linear Light Source Lens for Uniform Illumination
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Solution Overview
Problem
Existing linear light source apparatuses for image reading have low light efficiency and uneven light distribution due to the knurling shape of light guiding plates, leading to increased heat output and size constraints, making it difficult to miniaturize the system.
Innovation Solution
A linear light source apparatus with a lens that diffuses light flux in a predetermined region at a specific angle, creating a sparse distribution on the optical axis and a denser distribution outside, allowing for controlled light quantity distribution and compact design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a light guiding plate with knurling shape is used to guide light from LED, then light can be distributed along the plate, but light efficiency is low and unevenness in light quantity occurs
Solution Approach 1:
The invention extracts the light guiding function from the traditional knurling-shaped light guiding plate and replaces it with a reflective plate having a specific reflective pattern. This separation allows the light source structure to be optimized independently from the light distribution function, eliminating the light loss inherent in light guiding plate materials while achieving uniform light distribution through controlled reflection.
Solution Approach 2:
The invention changes the fundamental parameter of light guidance from refractive/index-based (light guiding plate) to reflective angle-based (reflective plate with specific pattern). By controlling the reflection angles and positions of reflective portions, the system achieves precise light quantity distribution without the energy loss associated with light guiding plate materials.
2Illumination intensity
If high-power LED is used to illuminate source document, then illumination intensity is sufficient, but heat output increases temperature of mounting member and light guiding plate
Solution Approach 1:
The invention extracts the light distribution function from the light guiding plate structure, replacing it with a reflective plate system. This eliminates the heat accumulation problem in light guiding plates while maintaining sufficient illumination intensity through optimized reflective geometry that directs maximum light toward the document surface.
Solution Approach 2:
The invention replaces the light guiding plate's refractive light control mechanism with a reflective plate system using controlled reflection. This substitution allows for more efficient light direction with less heat generation, as reflective systems typically have lower thermal mass and better heat dissipation characteristics compared to light guiding plate materials.
3Illumination intensity
If light guiding plate width is made equivalent to or larger than source document width, then light coverage is sufficient, but size of light source apparatus cannot be reduced below document size
Solution Approach 1:
The invention transitions from a two-dimensional light guiding plate surface to a three-dimensional reflective plate structure with controlled reflection angles. By using angular control in the third dimension (reflection angle), the system achieves wide light coverage without requiring a proportionally large horizontal footprint, enabling compact apparatus design.
Solution Approach 2:
The reflective plate is divided into multiple reflective portions with different reflection angles and positions. This segmentation allows each portion to target specific areas of the document, achieving complete coverage through coordinated reflection from smaller, modular reflective elements rather than requiring a single large light guiding plate.
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 enhances light efficiency and uniformity, enabling a compact linear light source that can be used in image reading applications with improved light distribution and reduced size constraints.
Implementation Method 1
a lens allowing light emitted from the light emitting element to converge with respect to the first direction and outputting flat light flux that extends linearly in the second direction being orthogonal to the first direction. The lens diffuses light flux in a predetermined region including an optical axis of the light emitting element, out of the light incident from the light emitting element, in the second direction at a predetermined diffusion angle. And the lens diffuses light flux in the region outside the predetermined region including the optical axis, in the second direction at a diffusion angle smaller than the diffusion angle of the light flux in the predetermined region including the optical axis.
Data Source
AI summary
A linear light source apparatus is provided, being configured to convert light emitted from one light emitting element to light extended linearly, and output thus converted light. There is a lens that diffuses light flux within a predetermined region including the optical axis of the light emitting element, out of the light incident from the light emitting element, at a predetermined diffusion angle in the second direction (x-direction). The light is made to converge with respect to the first direction (y-direction). This converts the light from one light emitting element to light extended linearly and outputs the converted light. As for the second direction (x-direction), it is possible to make the light flux sparse in the predetermined region, and in the region outside thereof, the light flux is rendered to be dense. Therefore, a distribution of light quantity in the longitudinal direction (x-direction) is implemented by controlling the light flux density, upon employing the linear light source apparatus as a light source of the image reading apparatus.