Ring-Shaped LED Flash Module for Uniform Camera Lighting
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Solution Overview
Problem
Conventional camera flash units in compact devices, such as smartphones, suffer from low lighting quality due to design challenges in directing light effectively around a small camera lens, resulting in non-uniform and inefficient light distribution.
Innovation Solution
A ring-shaped LED flash module is designed with two LED assemblies mounted on a Metal Core Printed Circuit Board (MCPCB) within a transparent light guide, utilizing total internal reflection and tailored optical features on the light guide's surface to achieve symmetrical light emission around the camera lens, with heat sinking capabilities for prolonged use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If conventional LED flash units are used in compact devices, then the device size is reduced, but the lighting quality deteriorates due to non-uniform light distribution
Solution Approach 1:
The flash unit is segmented into multiple LED assemblies (typically three) arranged around the camera lens, with each LED assembly containing multiple LEDs. This segmentation allows light to be emitted from multiple locations simultaneously, creating more uniform illumination across the scene while maintaining a compact form factor.
Solution Approach 2:
The LED assemblies are arranged in a circular pattern around the camera lens, transitioning from a single-point light source to a distributed three-dimensional light distribution. This dimensional change enables uniform light emission in all directions within the camera's field of view, significantly improving lighting quality without increasing device volume.
2Device complexity
If small flash units are designed for compact cameras, then the device complexity is reduced, but the lighting quality deteriorates due to difficulties in directing light effectively
Solution Approach 1:
The flash unit merges the LED light sources with the camera lens assembly by positioning the LED assemblies around the lens rather than separating them. This integration allows the light to be naturally directed toward the lens and subject, improving lighting quality while simplifying the overall device structure and reducing the number of separate components.
Solution Approach 2:
The circular light guide structure serves multiple functions simultaneously: it distributes light uniformly from the LED assemblies, directs light toward the camera lens, provides structural support, and defines the flash unit's compact form factor. This multi-functionality improves lighting quality without increasing device complexity.
3Illumination intensity
If LED assemblies are arranged around the camera lens, then uniform light emission is achieved, but the manufacturing precision requirements increase
Solution Approach 1:
The light guide structure incorporates localized optical features at specific positions around the circular path, including reflective surfaces positioned opposite each LED assembly and light extraction features at controlled intervals. These localized features compensate for variations in LED positioning and ensure uniform light emission, reducing the impact of manufacturing tolerances on overall performance.
Solution Approach 2:
The design allows for variations in LED assembly positioning and light extraction feature dimensions within specified tolerances while maintaining uniform light emission. By designing the optical system to be insensitive to parameter variations, the manufacturing precision requirements are effectively reduced without compromising lighting quality.
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 uniform and symmetrical light emission profile with peak intensity at the camera's axis, reducing visible hot spots and enhancing lighting quality, while simplifying manufacturing and reducing the visibility of the phosphor component.
Implementation Method 1
Since the light guide material (e.g., transparent acrylic, poly(methyl methacrylate) (''PMMA''), etc.) directly encapsulates the LEDs and MCPCB, there is very good optical coupling of the LEDs to the light guide material.
Implementation Method 2
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 3
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 4
The portions of the MCPCBs that protrude out from the light guide act as air-cooled heat sinks.
Data Source
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.