Ring-Shaped LED Flash Light Guide for Uniform Camera Illumination
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Solution Overview
Problem
Conventional camera flash units for compact devices, such as smartphones, suffer from low lighting quality due to design constraints, resulting in non-uniform and inefficient light distribution around the camera lens.
Innovation Solution
A ring-shaped LED flash system is implemented, where two LED assemblies are molded into a transparent light guide with optical features to achieve symmetrical light emission, utilizing total internal reflection and diffusive reflection to ensure uniform light distribution around the camera lens, with heat sinking mechanisms for prolonged use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If conventional LED flash units use tiny Fresnel lenses and small LED components to fit compact cameras, then the device size is reduced, but the lighting quality and uniformity of light distribution deteriorate
Solution Approach 1:
The patent transitions from conventional point-source LED placement to a ring-shaped light guide structure that surrounds the camera lens. This dimensional change from a compact point source to an extended环形 structure enables symmetric light distribution in all directions around the lens, improving lighting quality while maintaining compact form factor suitable for smartphones and action cameras.
Solution Approach 2:
The patent introduces a light guide as an intermediary component between the LED light sources and the camera lens. The light guide material (transparent acrylic or PMMA) with embedded optical features acts as a mediator that redistributes light uniformly around the lens, converting the directional light from LEDs into symmetric 360-degree illumination without requiring larger components.
2Ease of manufacture
If LED assemblies are positioned off-center to accommodate the camera lens, then the lens positioning is simplified, but the light distribution uniformity and symmetry deteriorate
Solution Approach 1:
The patent employs asymmetric LED assembly placement (180 degrees apart in the ring) combined with symmetric optical features in the light guide to achieve symmetric light distribution. The asymmetric positioning of light sources coupled with the symmetric ring structure and optical features creates balanced illumination around the central lens, simplifying lens integration while ensuring uniform light distribution.
Solution Approach 2:
The patent implements local optical features (prisms, roughened surfaces, extraction features) at specific locations within the light guide to control light distribution. These localized optical modifications enable precise control of light extraction and reflection patterns, ensuring uniform illumination while accommodating the camera lens in the center opening of the ring structure.
3Device complexity
If conventional flash designs use separate LED components and lenses, then component assembly is simplified, but the overall device complexity and manufacturing tolerance sensitivity increase
Solution Approach 1:
The patent merges multiple components into an integrated ring-shaped flash assembly where LED assemblies, light guide, and optical features are combined into a single molded structure. The light guide material directly encapsulates the LED assemblies and MCPCB, eliminating the need for separate mounting and alignment of multiple components, thereby reducing manufacturing complexity and tolerance sensitivity.
Solution Approach 2:
The ring-shaped light guide structure serves multiple functions simultaneously: it acts as the structural framework, the light distribution medium, the mounting substrate for LED assemblies, and the housing for the camera lens opening. This multi-functionality reduces the number of separate components needed and simplifies the overall assembly process while maintaining precise light distribution characteristics.
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 a symmetrical and uniform light emission profile aligned with the camera lens, reducing visible hot spots and enhancing lighting quality, while being easier to manufacture and less prone to manufacturing tolerances issues compared to traditional designs.
Implementation Method 1
The light emitted from the two LEDs is reflected off the smooth side and bottom surfaces of the light guide by total internal reflection ("TIR") until the light impinges on the top surface of the light guide, where the light exits.
Implementation Method 2
The top surface of the light guide has optical features for extracting the injected light, such as a roughened surface, prisms, and the like.
Implementation Method 3
The portions of the MCPCBs that protrude out from the light guide act as air-cooled heat sinks. Heat sinking is important where the LED is steadily turned on, such as for video or being used as a flash light.
Data Source
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AI summary
A flash system for an electronic device includes a ring-shaped light guide having a central opening. A camera lens is positioned in or behind the opening. A first light emitting diode ("LED") is mounted on a printed circuit board ("PCB"), and the LED and PCB are encapsulated by a molded light guide of the flash system. An identical LED and PCB are encapsulated at an opposite end of the molded light guide (i.e., 180 degrees away). The back surfaces of each PCB diffusively reflects light from the LED on the other PCB. Light extraction features on the light guide surface uniformly leak out light from the LEDs. The light emission profile of the light guide has a peak axially aligned with the central opening of the light guide and rolls off to the edge of the camera's field of view.