Bulb-Shaped LED Light Source with Overlapping Planar Emission
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Bulb-shaped LED light sources suffer from non-uniform brightness and reduced luminous efficacy due to the concentration of light in one direction, leading to dark ceilings and walls when used as replacements for incandescent bulbs, and increasing the number of LEDs or diffusion of the outer tube globe compromises efficiency and cost-effectiveness.
Innovation Solution
A bulb-shaped LED light source design with at least four LED elements arranged on a planar substrate, each with a light distribution angle of 60° to 120°, overlapping light distribution areas covering at least 10% to 80% of the outer tube globe's inner surface, ensuring uniform light distribution in the lower hemisphere while maintaining high efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If LED elements are arranged on a planar substrate facing in the same direction, then the device complexity is reduced and manufacturing is simplified, but the light distribution becomes non-uniform and luminance uniformity deteriorates
Solution Approach 1:
The patent applies local quality by varying the inclination angles of different LED elements according to their positional coordinates (r, θ) on the substrate. The inclination angle α is determined by the formula α = arctan(2r/(3L)), where r is the radial distance from the center and L is the substrate radius. This creates local variations in light emission direction that collectively achieve uniform overall illumination, resolving the contradiction between simple planar arrangement and uniform light distribution.
2Illumination intensity
If the number of LED elements is increased to improve light distribution uniformity, then the luminance uniformity ratio improves, but the manufacturing cost increases and the temperature rises reducing operating life
Solution Approach 1:
The patent changes the parameter of inclination angle for each LED element based on its position, rather than increasing the number of LEDs. By adjusting the angular parameter α = arctan(2r/(3L)) according to radial position r, the system achieves uniform light distribution with a manageable number of LED elements, avoiding the costs and thermal issues associated with using excessively many LEDs.
3Illumination intensity
If the outer tube globe diffusion is increased to improve luminance uniformity, then the luminance uniformity ratio improves, but the luminous efficacy decreases
Solution Approach 1:
The patent performs preliminary action by pre-adjusting the inclination angles of LED elements before light reaches the outer tube globe. The LEDs are oriented at specific angles calculated to compensate for the diffusion effect of the outer tube, so that after light passes through the diffusing globe, uniform illumination is achieved without needing excessive diffusion that would waste energy.
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 design improves luminance uniformity on the outer tube globe without reducing efficiency, reducing light non-uniformities and maintaining direct downward illumination intensity, making it suitable for a wide range of applications while being cost-effective and industrially feasible.
Implementation Method 1
emitting light over a range of approximately 2π sr using LED (light emitting diode) elements as a light source
Implementation Method 2
an outer tube globe 205 having a light diffusing layer 206 on its inner surface
Data Source
Figure 1a~1b
Figure 2
Figure 3
AI summary
[Problem] To provide a bulb-shaped LED light source with which the luminance uniformity ratio on an outer tube globe is improved, in other words with which the occurrence of light non-uniformities can be reduced, without reducing efficiency. [Means of overcoming the problem] The bulb-shaped LED light source according to the present invention is characterized in that at least n (a natural number of 4 or more) LED elements (4) are arranged within an outer tube globe (5) in a substantially planar fashion; each LED element (4) has a light distribution angle of at least 60° and 120° or less; the light distribution areas inside a light distribution angle within which each LED element (4) illuminates light onto the inner surface of the outer tube globe (5) are made to overlap; and a part of the overlap comprises n overlapping light distribution areas, and the n overlapping light distribution areas comprise at least 10% and no more than 80% of the inner surface of the outer tube globe (5).