Ring Light Guide for Uniform Camera Flash Illumination
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Solution Overview
Problem
Ring flashes in camera devices, especially those using individual LEDs, often produce hot spots and non-uniform illumination due to their design, particularly in macrophotography where shadows can be problematic.
Innovation Solution
A ring-shaped light guide module incorporating LEDs with vertical light-emitting sides and a light guide featuring a reflector film, diffuser or collimating film, and a printed circuit board for uniform illumination, utilizing total internal reflection and strategic light extraction through a textured or ink-patterned surface to minimize shadows.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If individual LEDs are used in ring flash, then device complexity is reduced, but illumination uniformity deteriorates causing hot spots
Solution Approach 1:
A light guide is introduced as an intermediary component between the LED and the camera lens. The light guide receives light from the LED and redistributes it uniformly around the ring, converting the point-source illumination into distributed uniform illumination without adding complex optical systems
Solution Approach 2:
The light guide utilizes changes in refractive index parameters to control light propagation. By incorporating a reflector film with different refractive index than the light guide material, and using textured or ink-patterned surfaces, the light distribution parameters are optimized to eliminate hot spots while maintaining uniform illumination
2Ease of manufacture
If simple transmission optics are used, then manufacturing cost is reduced, but light distribution uniformity deteriorates
Solution Approach 1:
Different regions of the light guide are given different local properties: the inner sidewall has a reflector film for light redirection, the outer sidewall has textured or ink-patterned surfaces for light extraction, and the top surface has specific optical properties. This localized differentiation achieves uniform illumination without requiring complex optics throughout the entire structure
Solution Approach 2:
An ink pattern is applied to the outer sidewall of the light guide to control light extraction. The ink pattern creates specific optical absorption and scattering characteristics that enable uniform light distribution while using simple, cost-effective materials and manufacturing processes
3Object-affected harmful factors
If LEDs are positioned close to the lens, then shadow reduction is improved, but hot spots are generated due to concentrated light emission
Solution Approach 1:
The light emission is segmented and distributed around the entire ring rather than concentrated at a single point. The light guide divides the LED's light output into multiple extraction points around the outer circumference, creating uniform illumination that surrounds the lens and eliminates both shadows and hot spots
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 uniform and vectored light emission, reducing shadows and enhancing image quality in low-light conditions by ensuring consistent illumination around the camera lens.
Implementation Method 1
utilizing total internal reflection and strategic light extraction through a textured or ink-patterned surface
Data Source
AI summary
A device includes a light-emitting device (LED) having at least two vertical light-emitting sides, and a ring-shaped light guide having a bottom side, a top side comprising a light-emitting surface, an inner sidewall, and an outer sidewall defining an indentation having at least two vertical in-coupling surfaces mated to the at least two vertical light-emitting sides of the LED.