Ring COB LED Light Cover for Uniform Power Tool Illumination
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Solution Overview
Problem
The existing illumination systems for power tools, particularly those using chip-on-board light emitting diodes (COB LEDs), suffer from non-uniform illuminance distribution and light loss, which affects the effectiveness of work area illumination.
Innovation Solution
The integration of a light cover with a cover slope that totally reflects light from the LED chip forward, combined with an uneven light entrance surface to diffuse light, and an illuminance sensor with an LED control circuit to adjust light output based on reflected light levels, ensures appropriate illuminance and uniform distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a chip-on-board light emitting diode is used to illuminate the work target, then the light output amount increases and the work space is brightly illuminated, but the illuminance distribution becomes non-uniform and light loss occurs
Solution Approach 1:
The LED chip is divided into multiple segmentation regions (first, second, third, and fourth segmentation regions) corresponding to different radial distances from the central axis. Each region emits light with different intensities to compensate for the natural decay of light intensity with distance, achieving uniform illuminance distribution across the work target.
Solution Approach 2:
Different regions of the LED chip are assigned different light emission characteristics. Specifically, the light emission intensity varies by radial position, with inner regions emitting more light and outer regions emitting less light. This local differentiation of emission quality resolves the non-uniform illuminance distribution problem.
2Area of stationary object
If the LED chip emits light in all directions, then the light coverage is maximized, but light loss increases and forward illumination efficiency decreases
Solution Approach 1:
A light cover is introduced as an intermediary component between the LED chip and the work target. The light cover includes a light transmission portion that directs light forward and an inner cylindrical portion with a cover slope that totally reflects oblique light forward. This mediator converts omnidirectional light into directed forward light, improving illumination efficiency while maintaining coverage.
Solution Approach 2:
The cover slope in the inner cylindrical portion converts oblique light that would otherwise be lost into useful forward-directed light through total reflection. This transforms potential light loss into beneficial illumination, improving forward light output efficiency.
3Illumination intensity
If the light emission intensity is increased to improve illumination, then the work space is brighter, but glare is generated and comfort decreases
Solution Approach 1:
The light emission intensity is differentiated by region, with the central region providing primary illumination and peripheral regions providing supplementary illumination. This localized emission control delivers adequate brightness while reducing concentrated glare by distributing light more evenly across the field of view.
Solution Approach 2:
The light cover acts as a mediator that diffuses and redirects light, preventing direct concentrated beams from reaching the user's eyes. The light transmission portion and cover slope work together to soften the light output, maintaining brightness while eliminating glare.
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
This configuration enhances light output efficiency, providing uniform illuminance and preventing worker discomfort from excessive glare, thereby improving the irradiation state of the chip-on-board LED.
Implementation Method 1
The inner cylindrical portion may include a cover slope that totally reflects light from the LED chip forward
Data Source
AI summary
A power tool includes a motor, an output shaft, a chip-on-board light emitting diode, and a light cover. The output shaft is rotated by a rotational force of the motor. The chip-on-board light emitting diode is disposed around the output shaft. The chip-on-board light emitting diode includes: a substrate having a circular ring portion; and an LED chip disposed on a front surface of the circular ring portion. The light cover is fixed to the substrate. The light cover includes: an inner cylindrical portion disposed radially inside with respect to the circular ring portion; and a light transmission portion through which light emitted from the LED chip passes. The inner cylindrical portion includes a cover slope that totally reflects light from the LED chip forward.