Cylindrical Parabolic Mirror Lighting Unit for Uniform Illumination
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Solution Overview
Problem
Image scanning devices face challenges in achieving uniform illumination and large lighting depth when scanning documents with uneven surfaces, such as book manuscripts or wrinkled paper, due to fluctuations in brightness along the lighting depth direction, and existing solutions either compromise on compactness or lead to temperature-related performance deterioration.
Innovation Solution
A lighting unit comprising a light source array in the main scanning direction, a cylindrical parabolic mirror with a specific curvature, and a heat-radiating plate, which produces roughly parallel light rays for efficient illumination and effectively manages heat dissipation, ensuring uniform illumination and large lighting depth without increasing the size of the optical system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If multiple reflective surfaces are arranged to provide large lighting depth, then the lighting depth increases, but the illumination uniformity deteriorates due to multiple peaks in angular component
Solution Approach 1:
The patent applies a parabolic reflective surface with specific curvature to transform divergent light from LED sources into parallel light rays. The parabolic shape equation y = (x²)/(4f) is used to ensure that light rays reflecting from the surface become parallel to the optical axis, achieving both large lighting depth and uniform illumination without the multiple peaks problem caused by flat or multi-surface designs.
2Illumination intensity
If a parabolic reflective mirror and lenses with two types of curvature are used to achieve parallel light rays, then illumination uniformity improves, but the device size and complexity increase
Solution Approach 1:
The patent extracts and eliminates unnecessary optical components from the system. By using only a parabolic reflective surface without additional lenses or complex multi-curvature elements, the design achieves parallel light output while significantly reducing optical system size and complexity compared to conventional designs that require multiple optical elements.
Solution Approach 2:
The parabolic reflective surface serves multiple functions simultaneously: it acts as both the light redirecting element and the illumination uniformity control element. This single component replaces what would traditionally require separate lenses and reflective surfaces, simplifying the overall optical system while maintaining performance.
3Stability of the object's composition
If light-emitting diodes are mounted on a circuit substrate anchored to a metal support section, then structural stability improves, but heat dissipation deteriorates causing temperature rise
Solution Approach 1:
The patent introduces a heat-radiating plate as an intermediary component between the LED light source and the metal support structure. This plate serves as a thermal interface that efficiently conducts heat away from the LEDs while maintaining the structural stability provided by the metal support, thereby resolving the contradiction between structural integrity and heat dissipation.
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 provides efficient and uniform illumination across documents with varying distances, maintaining performance and preventing temperature-related issues, thus enabling clear imaging of documents with uneven surfaces while maintaining a compact device design.
Implementation Method 1
a cylindrical parabolic mirror which reflects light from the light source and forms roughly parallel light rays
Implementation Method 2
a heat-radiating plate extending in the main scanning direction and having a contact section in contact with a surface opposite to a surface on which the light-emitting elements of the light source substrate are mounted
Data Source
AI summary
A lighting unit includes LED chips positioned in an array form in a main scanning direction on LED substrates. Cylindrical parabolic mirrors each form a shape in which a cylindrical paraboloid having curvature with respect to an sub-scanning direction has been clipped by an axial plane that is perpendicular to the vertex of the cylindrical paraboloid in the main scanning direction, and project light emitted from the light source on an illumination area of an illuminated item. Each cylindrical parabolic mirror includes an anchoring section that is provided at the vertex of the cylindrical paraboloid, and extends from the vertex in an outside direction of the cylindrical paraboloid. Heat-radiating plates each have a contact section that is in contact with the LED substrate, and a non-contact section. Each LED substrate is interposed between the contact section of the heat-radiating plate and the anchoring section of the cylindrical parabolic mirror.