Micro-Cylindrical Fresnel Lens for Uniform Rectangular Illumination
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Solution Overview
Problem
Conventional Fresnel lenses in LED flashlights produce non-uniform illumination patterns due to their circular or oval shape, which affects the quality of photographs, especially with high-pixel cameras, as they fail to concentrate light effectively within the finite LED light sources.
Innovation Solution
A SMD type Fresnel LED micro flash light structure featuring a micro-cylindrical Fresnel lens with a cylindrical plano-convex lens and bar teeth-shaped sections, arranged in a rectangular configuration to provide a uniform rectangular illumination pattern, utilizing an array-type light source and housing design that enhances light concentration and distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a conventional Fresnel lens with circular or oval shape is used, then the structure is simple and thin, but the illumination pattern is non-uniform and affects photograph quality
Solution Approach 1:
The Fresnel lens is divided into multiple independent zones (first Fresnel zone plate, second Fresnel zone plate, and third Fresnel zone plate) with different shapes and functions. Each zone plate can be independently designed to control light distribution in specific directions, achieving uniform rectangular illumination through the superposition of multiple segmented optical paths
Solution Approach 2:
The patent introduces asymmetric design by using different shaped zone plates (circular, oval, and rectangular) arranged in specific configurations. The rectangular Fresnel zone plate in the center and oval/circular plates on sides create asymmetric light distribution that combines to form a uniform rectangular illumination pattern, breaking the limitation of traditional symmetric circular/oval lens designs
2Illumination intensity
If a single LED with single Fresnel zone plate is used, then the device is simple, but the illumination pattern is oval-shaped and not suitable for high-pixel cameras
Solution Approach 1:
Multiple LEDs (first LED and second LED) are combined with multiple Fresnel zone plates to create a unified optical system. The light from multiple LED sources is merged and redistributed through the composite Fresnel lens structure, achieving uniform rectangular illumination that matches high-pixel camera requirements while maintaining compact form factor
Solution Approach 2:
The patent transitions from traditional single-dimension (circular/oval) illumination to two-dimensional rectangular illumination control. By arranging Fresnel zone plates in a planar configuration with different shapes and orientations, the system controls light distribution in both horizontal and vertical dimensions simultaneously, creating a uniform rectangular illumination pattern suitable for modern camera sensors
3Illumination intensity
If conventional Fresnel lens with 8-shaped illumination pattern is used, then the lens structure is simple, but the minimum luminous intensity is much lower than peak intensity
Solution Approach 1:
Different regions of the Fresnel lens are assigned different optical properties through the use of multiple zone plates with varying shapes, sizes, and positions. The central rectangular zone plate provides strong central illumination, while the side oval/circular zone plates fill in the peripheral areas, creating local optimization of light distribution that raises the minimum luminous intensity across the entire illumination area
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 substantially rectangular-shaped illumination pattern with uniform luminance, significantly reducing the difference in luminous intensity across the illumination area, providing at least 30% greater minimum luminous intensity compared to peak values, thus improving photographic quality.
Implementation Method 1
The micro-cylindrical Fresnel lens covers a top end of the housing, which includes a cylindrical plano-convex lens, and two teeth-shaped lens sections respectively arranged at two sides of the cylindrical plano-convex lens
Implementation Method 2
A SMD type Fresnel LED micro flash light structure, having an improved Fresnel lens, and at least two LED lights for providing a brighter and uniform illumination pattern
Data Source
AI summary
A SMD type Fresnel LED micro flash light structure, which is adapted to a camera of a mobile phone, includes a housing, an array-type light source and a micro-cylindrical Fresnel lens. The housing has a bottom wall and a plurality of side walls, and defines a longitudinal direction and a width direction. The array-type light source is disposed on the bottom wall along the longitudinal direction. The micro-cylindrical Fresnel lens covers the housing, and includes a cylindrical plano-convex lens, and two teeth-shaped lens sections respectively arranged at two sides of the cylindrical plano-convex lens. Each teeth-shaped lens section has a plurality of bar teeth-shaped lenses. The cylindrical plano-convex lens and the bar teeth-shaped lenses are parallel to each other along the width direction. A central axis of the cylindrical plano-convex lens is corresponding to a central position of the array-type light source.