Study Of Highway Photobiological Lighting Mechanism And Cirtopic LED Phosphors

With the development of economy,the living standard of the people is improving observably,Especially in the increase in the number of motor vehicles,while the rapidly increasing in traffic flow has a more stringent demand for road traffic.Especially in a dark light environment,traffic light sources are not just so simple to illuminate.Among them,there are high requirements for the types of light sources,color temperature,color rendering index,and wavelength.The design of traffic lighting will also focus on the impact of visual effects.With the continuous exploration of science,it is found that the human eye cell contains a new visual cell—Cirtopic Vision,also called non-visual effect of photobiology.The human body will show different circadian rhythms under different lighting environments affected by it,this will be a new challenge to the design of traffic lighting.The photobiological effect is different from the well-known bright and dark vision.It is actually a non-visual effect that does not participate in visual imaging.The biological rhythm and intensity of humans are controlled by it,it also affects the pupil size of the eyes and the secretion of melatonin.The peak of its spectral sensitivity function is about 490 nm.During driving,if the driver is under different road lighting sources,it will produce different photobiological effects.Different photobiological effects mean different levels of physiological alertness,which will affect the driver’s reaction time to make a decision on obstacles and unexpected situations during driving,those things will affects driving safety ultimately.In this context,this study combines the research results of road lighting at domestic and overseas,launched research on photobiological effects in road lighting.Tested human reaction time under different light sources and introduced flash fusion frequency threshold as a reference standard.It is proposed to consider the influence of intermediate vision on road lighting safety when designing road lighting,and also consider the influence of non-visual effects on traffic lighting safety.Nowadays,in addition to high-pressure sodium lamps,low-pressure sodium lamps,and electrodeless lamps,the light sources we use for road traffic lighting,LED-Light Emitting Diode are gradually loved by people.Compared with traditional light sources,the biggest advantage of LEDs is their outstanding energy-saving effect.Their energy consumption is only one tenth of incandescent lamps and one-quarter of energy-saving lamps.In addition,it has the advantages of working in a high-speed switching state,environmental protection,and fast response speed.After investigation,it was found that traffic safety is closely related to road lighting,and the safety impact of its photobiological effect is much greater than that of indoor office lighting.Although in recent years,around the impact of different artificial light sources on Cirtopic Vision,scientific researchers in many countries have carried out some related research,but Cirtopic Vision research on traffic lighting is still rare at home and abroad.Therefore,studying the influence of LED light source on driver’s sobriety can provide relevant basis and technical support for the design and update of road lighting.For the luminescence of LEDs,based on the research of photobiological effects,we have prepared a series of adjustable special LED phosphors for highway traffic lighting that meet the human citropic vision.In order to realize the idea of a light-emitting diode near 490nm that matches the peak sensitivity of cirtopic visual spectrum,we prepared a continuous solid-solution LED phosphors with adjustable light emission based on the principle of the same crystal structure and different doping concentrations.Sr₂MgSi₂O₇and Ca₂MgSi₂O₇,which belong to the tetragonal yellow feldspar structure,have the same space group-P-42₁m（113）.The luminescence centers of Sr₂MgSi₂O₇:Eu²⁺and Ca₂MgSi₂O₇:Eu²⁺phosphors prepared by high-temperature solid-phase method at room temperature are located at 466 nm and 527 nm,respectively.Because of the similar ionic radii of Sr²⁺（0.127 nm）and Ca²⁺（0.112 nm）,we can obtain(Sr_1-xCa_x)₂MgSi₂O₇:Eu²⁺（0≤x≤1）continuous solid solution LED fluorescence by changing the concentration of the two powders,when adjusting the concentration of x to a certain value,we can get the LED phosphors with the luminescence center near 490 nm.The innovations of this article:1.The Cirtopic visual effect of monochromatic light is verified;2.A new special light source for driving safety is proposed;3.(Sr_1-xCa_x)₂MgSi₂O₇:Eu²⁺（0≤x≤1）Continuous solid solution LED phosphors are prepared successfully;4.Successfully modulated a single-peak phosphor with a luminescence center near 490 nm,and its FWHM（full width at half maximum）is narroww than Cirtopic’s visually sensitive spectrum.