Lighting that influences mood is often confused with Human-Centric Lighting (HCL). However, lighting plays a broader role in biological functions, including both beneficial and potentially harmful effects, depending on how it's applied. Although the specific parts of the light spectrum may vary, its impact is significant for both plants and animals, leading to observable results.
The industry has invested considerable research into plant growth and animal farming, sometimes even more than what is done for human lighting. This article explores the various biological effects of different wavelengths on plants, livestock, and humans, comparing current knowledge across species to inspire advancements in HCL.
Current Status of Horticultural Lighting
Bioactive spectral control has become common in plant cultivation. Industrial applications are expanding, and further research is expected. Today’s basic research focuses on how plants behave under different wavelengths.
Plants respond to cryptochromes, phototropins, and phytochromes, showing stronger leaves and greater stress resistance under wavelengths below 400 nm (UV radiation). These effects are not only seen in isolated UV exposure but also when combined with other wavelengths. Additionally, small amounts of UV can help prevent fungal infections.
Between 400 nm and 500 nm, blue light helps reduce transpiration, which is useful in refrigerators to keep vegetables fresh. However, excessive blue light can slow growth and cause dwarfism in plants.
Green light (600–700 nm) counteracts this effect, helping maintain leaf structure. Red light (700–800 nm) promotes larger flowers and compact growth, especially affecting the aroma of edible plants.
Combining these wavelengths creates tailored lighting scenarios that enhance plant growth while optimizing energy use and quality. By adjusting the spectrum, lighting can be adapted to different growth stages, improving efficiency. Multi-channel systems can suppress unwanted growth factors at any time. For example, red light at the right moment helps tomatoes ripen efficiently without extending root length.
However, defining spectral exposure based solely on a single μmol value is ineffective. It only indicates output, not actual biological impact. For practical use, splitting light into wavelength ranges and assigning specific tasks is more effective.
Current Status of Animal Husbandry Lighting
In animal farming, tunable spectral sources are still developing. While some effects have been observed, the underlying biological mechanisms remain unclear. Artificial lighting is increasingly used in livestock facilities, especially as more farms operate indoors without natural sunlight. With rising meat demand, poultry has become the top choice globally, surpassing pork.
Poultry grows quickly—chickens reach 1.8 kg in seven weeks. Green light supports muscle development, while blue light increases hormone production. Yellow-white light improves food absorption. Red light reduces aggression and cannibalism, potentially reducing antibiotic use, though exact wavelength studies are limited. Chickens have a wider visual range than humans, making conventional lighting less effective.
Blue light at 480 nm keeps cows awake and boosts milk production by 8%. Cows cannot see beyond 640 nm.
Research on lighting’s impact on pigs is limited due to market conditions. In such applications, technology matters. Lighting must resist stroboscopic effects. Livestock and plants process visual stimuli faster than humans, so constant current operation is ideal for health benefits.
For dimming, simple PWM should be avoided. Instead, clean pulse control with synchronization is needed, especially in multi-channel systems. Poorly synchronized lighting can stress animals, affecting product quality.
Simple Comparison of Plants, Animals, and Humans
Comparing plant and livestock lighting shows similar dominant wavelengths. However, the exact composition remains unclear. Human biostimulation from single wavelengths is still under study. Blue light at 480 nm inhibits melatonin, marking an early step in HCL applications.
Plants, humans, and chickens show similar sensitivity to wavelengths. Sunlight forms the basis of all life, with environmental factors shaping its spectrum.
Research across plants, animals, and humans reveals common wavelength-dependent effects. For example, red light reduces cortisol levels in chickens.
Potential Consequences
Naming these processes and measuring their effects remains challenging. Lux and lumens don’t apply to infrared or ultraviolet. The V(λ) curve doesn’t effectively represent melatonin inhibition at 480 nm. Traditional lighting specs aren’t suitable for HCL, and HCL-compatible lights may lose efficiency.
For humans, HCL effects depend on exposure levels. For other organisms, μmol is the appropriate unit. Using species-specific sensitivity curves is common in chicken farming, but can “chicken lux†work for all birds?
Stroboscopic effects on livestock are well-known. Frequencies up to 1 kHz can harm animal health. Fast-reacting organisms like plankton and algae also require attention. Constant current-driven multi-channel drivers can improve outcomes by ensuring stable lighting.
In conclusion
Future standard lighting practices in livestock will influence general lighting, benefiting HCL through shared technical specifications. Ensuring safety requires clear product features.
TFT Display
TFT (Thin Film Transistor) is a thin film field effect transistor. The so-called thin film transistor means that each liquid crystal pixel on the Liquid Crystal Display is driven by a thin film transistor integrated behind it. This can Display Screen information at high speed, high brightness, and high contrast. TFT is an active matrix liquid crystal display.
The TFT-LCD liquid crystal display is a thin film transistor type liquid crystal display, also known as "true color" (TFT). TFT liquid crystal has a semiconductor switch for each pixel, and each pixel can be directly controlled by dot pulses, so each node is relatively independent and can be continuously controlled, which not only improves the response speed of the display, but also can be accurately controlled Display color gradation, so the color of TFT liquid crystal is more real.
In the fierce competition among many flat panel displays, why TFT-LCD can stand out and become the next-generation mainstream display is by no means accidental, it is the inevitable development of human technology and thinking mode. The liquid crystal has avoided the difficult light-emitting problem successively, and the light-emitting display device is decomposed into two parts by using the excellent characteristics of the liquid crystal as a light valve, namely the light source and the control of the light source. As a light source, brilliant results have been achieved in terms of luminous efficiency, full color, and life, and they are still being deepened. Since the invention of LCD, the backlight has been continuously improved, from monochrome to color, from thick to thin, from side fluorescent lamp type to flat fluorescent lamp type. The latest achievements in luminous light sources will provide new backlight sources for LCDs. With the advancement of light source technology, newer and better light sources will appear and be applied to LCDs. The rest is the control of the light source, the technology and process of the semiconductor large-scale integrated circuit are transplanted, the thin film transistor (TFT) production process has been successfully developed, the matrix addressing control of the liquid crystal light valve is realized, and the light of the liquid crystal display is solved. The cooperation of the valve and the controller enables the advantages of the liquid crystal display to be realized.
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