LED Horticultural Lighting Uniformity via Asymmetric Refraction
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Solution Overview
Problem
Current LED-based horticultural lighting systems fail to provide adequate light uniformity and spectral tuning for indoor applications, with light intensity decreasing as the emission angle increases relative to the optical axis, leading to uneven illuminance and 'hot spots' in grow beds.
Innovation Solution
The use of an array of LED fixtures with associated lenses that refract light to increase intensity with angle, providing a uniform or increasing illuminance across a larger surface area, and adjustable spectral output to simulate natural sunlight through combinations of broad-spectrum and fixed-color LEDs, controlled via wired or wireless protocols.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional LED fixtures with narrow beam angles are used, then light intensity is concentrated on the optical axis, but light uniformity deteriorates and hot spots are created
Solution Approach 1:
The patent segments the single LED light source into multiple LED elements arranged in an array, with each element having its own optical axis. This segmentation allows the light distribution to be divided into multiple overlapping beams, creating uniform illuminance across the grow bed surface while avoiding concentration of intensity in a single spot.
Solution Approach 2:
The patent employs asymmetric lens designs with different refractive indices for different angular ranges. The lens is configured to refract light at different angles for different portions of the LED array, creating a non-uniform refraction pattern that compensates for the natural beam spread and achieves uniform illuminance distribution across the target surface.
2Adaptability or versatility
If fixed-color LEDs are used, then spectral output is narrow-band, but adaptability to different plant growth phases deteriorates
Solution Approach 1:
The patent implements dynamic spectral tuning by controlling different LED color channels (e.g., blue, red, white) independently through PWM dimming or current control. The spectral composition can be adjusted in real-time to match different plant growth phases, transitioning from blue-heavy spectra during vegetative growth to red-heavy spectra during flowering, providing adaptability without permanent hardware changes.
Solution Approach 2:
The patent uses a multi-color LED array that can produce multiple spectral outputs from a single fixture. By combining different LED types (blue LEDs, red LEDs, white LEDs) in one array, the system achieves universal spectral coverage and can simulate different sunlight conditions (morning, noon, evening) or match different plant requirements, making one fixture serve multiple spectral functions.
3Use of energy by moving object
If high-power LEDs are used to increase light output, then energy efficiency improves, but heat generation increases causing plant stress
Solution Approach 1:
The patent segments the high-power LED array into multiple lower-power LED elements distributed across a larger surface area. This segmentation reduces the power density and heat generation at any single location, preventing localized overheating and plant stress while maintaining overall high light output through the combined emission of all LED elements.
Solution Approach 2:
The patent transitions from a single high-power LED source to a two-dimensional array of multiple LED elements. This spatial distribution across another dimension (surface area) disperses the heat generation, allowing better thermal management and reduced plant stress while maintaining total luminous output through the cumulative effect of all LED elements.
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 solution achieves uniform and increasing illuminance across grow beds, reducing the need for vertical distance and preventing plant burn, while simulating natural light conditions by adjusting intensity and spectral composition to match different phases of sunlight.
Implementation Method 1
utilizing an array of lenses to refract light emitted by an associated array of LEDs
Data Source
AI summary
An indoor horticultural system includes a grow bed and a lighting system arranged in proximity to the grow bed. The lighting system includes lighting fixtures having an optical axis and a light distribution whose intensity increases as the angle of the generated light increases in relation to the optical axis to increase cross-lighting. Alternately, the lighting system includes lighting fixtures mounted at varying angles and with varying beam widths so as to increase cross-lighting. Series connected light fixtures include a master light fixture that employs an intensity controller to control the intensity of light generated by each of the series-connected light fixtures, where the intensity controller derives operational power from an LED string contained within the master light fixture.