LUGIHT-GUIDE-design-method-provided-by-speos演示课件

.,Overview,Line-shaped lit appearance is achieved by this optical element.If it has no prism, no light can be extracted and just keep propagating. ( Its just a rod )The effect of prism is to make incident angle smaller than critical angle. Then some part of light is extracted.Optimal shape of prism depends on styling and regulation.,.,Light path and direction of extracted light can be changed byprism angle.,Variation of extraction,1 reflection,2 reflection,2 ( or more ) refractionand 1 reflection,.,Generally, some part of light goes out from prism side. In order to make it back in lightguide, mirror or white material is located at prism side.,Loss,.,Light guide Design,Interactive simulation is very useful for light guide design.The most important thing in light guide design is to observe the rays carefully.You can understand to which direction the rays are extracted and uniformity ofyour light guide approximately. Of course you need to make direct simulationafter it for precise evaluation.Styling of the lamp is different every time, this means optimal shape of prism isalso different every time. But there are some basic rules can be used in light guide design. Were going to learn them in following exercises.,It is recommended to increase the number of rays for interactive simulationso that you can understand the situation correctly.( Default number is 100 ),.,Preparation,Optical Axis,Create light guide with input elements ( green lines ).,Be careful of direction of yellow arrows.,Set parameters like below as starting value.,.,40deg,Extract the ray into the direction of 40deg.,LED,.,This is the easiest situation because direction of extracted ray tends to be shifted to propagating direction.You need to change end angle of prism if you want to change the direction of ray.,Propagating direction,LED,Check the result with direct simulation.,creation15min,Change end angle and find the value which extract the rays into right direction.,.,0deg,Extract the ray into the direction of 0deg.,LED,.,You can choose two types of light path.,2 ( or more ) refraction and 1 reflection,2 reflection,High efficiencyCan be difficult for molding,Less efficiencyEasy for molding,When you increase the value of end angle from exercise 1,you will achieve figure “A”. This is no more the light path ofsingle reflection. Figure “B” is completely different idea whichuses double reflection. “A” is better in terms of efficiency but shapeof prism become high and pointed.These two types of prism shape can be said as the one whichcan extract rays normal to guide curve. Angle values can be changedaccording to styling and source location but its not so far fromthe ones in left figures. You can use these shapes as starting.Create both type. Then change the value slightly and check how itworks.,A,B,LED,Check the result with direct simulation.,creation15min,.,-20deg,Extract the ray into the direction of -20deg.,LED,.,High efficiencyCan be difficult for molding,A,B,Low efficiencyEasy for molding,Idea is the same as exercise 2. Increase the value of end angle.In case of “A”, start angle is decreased in order not to be too pointed shape.Star angle also has effect to the path of rays. Be careful when you change start angle.Observe the rays with interactive simulation.This situation is the most difficult for light guide. Less capability to control rays andmore rays wasted.Create both type. Then change the value slightly and check how it works.,LED,Check the result with direct simulation.,creation15min,.,Now you know the basis to control the direction of extracted rays.And you can also understand better location of LEDs.,inside,outside,You have to aim this direction for regulation.,Rearlamp,Which location of LEDs makes it easy to design your light guide?,.,Bright,Dark,Large number of rays,Small number of rays,VE Result,Interactive Simulation ( You can estimate the uniformity of your light guide. ),Make it uniform.,.,Major part of rays are extracted in near area from LED.,Get back to the basis Why are these rays extracted?,Answer : Due to prisms.,Question : How can you reduce the number of rays extracted in near arear from LED?,.,The most efficient way to reduce the amount of extracted rays is hiding prisms with “offset” parameter.,In order to make it uniform, you need to hide prisms at the beginning to keep rays inside light guide and use wholeshape of prism at the end to extract more rays. You have to use design table to achieve it.,If you change the value of offset in “Constant” mode, it makes just decrease of whole efficiency and uniformity is not improved.,.,1/3,1/3,1/3,According to VE result, the last 1/3 part of light guide is dark. The whole number of prisms is 240, so you canunderstand you have to begin to change parameters at around 160th prism.,If you change the parameter suddenly, the result would be changed suddenly as well.Its better to change this parameter gradually.,The place you start to change the parameter and the gradient of parameter depend on styling andhow you want it looks like. In this phase, you have to make some iterations.,iteration30min,.,This part became worse.,It seems well extracted in interactive simulation. In such case, rays from some prisms are not extracted into correct direction.Adding curvature on prisms is useful because you can make spread thanks to it. Part of rays in the spread would be into correct direction and make your light guide more uniform. And this curvature also helps the brightness of far area from LED. Of course you can modify each prism angle individually but its complicated so using curvature is easy way to make some “tuning” for lit appearance.,?,Convex / concave is defined by positive / negative value of curvature.Behavior is different according to convex / concave. You need to try both and choose appropriate one and thenmodify the value of curvature.,1/4,1/6,We want to make it even better if possible.,.,It became much better than beginning