Over the past two decades, channel letters have been the most common type of illuminated signage in North America. The vast majority of these signs are illuminated with LED lighting.
在过去的二十年中，发光字成为了北美地区最常见的一种发光标识，并且它们主要都是通过LED光源来发光的。
According to recent studies, channel letters represent one in about three signs manufactured.Typically channel letters come essentially in four flavors:face lit,reverse or halo lit,front & back lit,open face.
根据最新研究表明，发光字的形成可以分成三个步骤，其中最具代表性的发光字又有四种表现形式：表面发光,反面发光,前后发光,开放式发光.
The first and most common is face lit letters. These “standard” channel letters typically have aluminum returns （or sides) and backs and typically have a translucent white or colored plastic face and are illuminated with colored or white neon or LEDs. Reverse halo letters are illuminated in the same manner; however, they are somewhat the opposite of standard channel letters and typically have an aluminum face and sides and a clear back. The result is a “halo” effect around the letters at night by reflecting off of the surface of the structure.
第一种表面发光的是我们最常见的发光字。这种标准发光字的边和背面通常都是使用铝合金的，并且表面是半透白或彩色的塑料，里面装有彩色或白色的霓虹灯或者LED灯。反面发光字发光也是同样的原理，但是他们使用了相反的工艺，通常反面发光字也用同样的方式来照明。然而，正面和侧面有铝质材料的标准发光字，背面是聚碳酸酯材料的标识。发光字在晚上通过表面结构反射后呈现“光环”效果。
Front/Back lit letters are basically a combination of the previous two and are designed with a translucent front and back face and can emit the same or different color from the front and a halo on the back. Open face letters are the least common but are typically used when the customer wants to create a skeleton neon effect. In this case the light source is visible and typically has a clear plastic front or is completely “open.” In this article I will examine some of the materials that are used in channel letter faces and some new materials that are optimized for LED light sources.
在以前的设计中，正面、背面发光字是基本组合，它们被设计成半透明的，而且从正面和背面都可以发射相同或不同颜色的光环。当顾客想要创造一个框架霓虹灯效果，开放式发光字是最常见的选择。在这种情况下，光源都是清楚可见的，并且标识前面都会使用清晰的塑料，这就是完全开放式的发光字。在这篇文章中，我将详细讲解一下,用在发光字表面的材料和一些LED照明材料。
Historically, face lit channel letters are made from acrylic or polycarbonate. Both acrylics and polycarbonates are thermoplastic polymers, which means they can be heated and shaped, as opposed to thermosetting polymers, which cure to a hard material and remain so even as new heat is applied. This allows both of these materials to be readily used for formed faces, although acrylic softens at a lower temperature.
纵观实际生活中，发光字的表面材料一般是亚克力或者聚碳酸酯。它们是热塑性聚合物，这意味着它们在加热后会变形。随着技术的发展，与热塑料聚合物相反特性的材料已经出现，它可以在加工处理硬的材料时保持它原来的形状。这表示所有的材料表面都是易于成型的，亚克力也是如此，它会在低温下变软。
This is also why indoor signs typically require use of a polycarbonate face – as they typically considered “low flammability” materials. Both SABIC Innovative Plastics and Bayer Makrolon manufacture versions that are 5VA flame rated and useful for manufacturing indoor and enclosure rated signs. Polycarbonate is also much more impact resistant than standard acrylic (but more expensive), although modified or “impact resistant” sign-grade acrylics are readily available that have much improved impact strengths.
这也是为什么室内标识被要求用聚碳酸酯作为表面材质-因为它有良好的阻燃性。这也是沙伯基础创新塑料(中国)有限公司和拜耳聚碳酸酯有限公司的室内标识的材料。聚碳酸酯比起亚克力来说会有更大的耐冲击性，不过价格也会更昂贵，这也说明亚克力在冲击强度方面有很大的改进余地。
Both polycarbonate and acrylic can transmit light efficiently. However, over the past decade a slew of new specialized sign-optimized plastics have been released as sign makers transitioned from neon to LEDs for channel letter illumination. Fifteen years ago almost all channel letters were illuminated with neon. Neon glass has to be a certain distance from the face and had to “stand off” from the sign back with a tube support.Therefore, almost all standard neon channel letters were 5-8” deep depending upon the height of the sign. Neon was forgiving in the sense that it is a 360 degree emitter, throwing light all around the inside of the letter, allowing for even illumination at these depths in all four flavors of channel letters.
聚碳酸酯和亚克力都可以高效的传输光。然而，过去十年出现了大量的新型专业标识，发光字制造标志已经从从霓虹灯过度到LED灯。十五年前差不多所有的发光字都是用霓虹灯来发光的。不过霓虹灯在玻璃表面和背后的管支架之间要保持足够的距离。因此，几乎所有的标准霓虹灯标识的深度都是5-8，具体多少要取决于标识离地面的高度。霓虹灯之所以被广泛应用，就在于它能360度全方位的发光效果，发出的光都环绕在发光字内部。
As LEDs began to replace neon, these small, directional light sources could be placed on the back of the letters opening up the possibility of more shallow, thinner channel letters. However, traditional face material caused hot spots at lower depths, especially under 3” deep. Plaskolite’s Optix LD light-diffusing acrylic and Bayer Makrolon LD polycarbonate sheets are both examples of modified plastics that have been optimized to allow maximum light transmission with minimum hot spots. Understanding both the mechanical and optical properties of the face material is important to making sure the sign meets the customer’s expectations and helps minimize fabrication and total material cost.
后来LED替换了霓虹灯，它是可以被放置在发光字背后的小的定向光源，可以显示笔画更细、字体大小更小的发光字。然而，传统的灯箱深度一般低于3英寸，美国Plaskolite有限公司的Optix LD-用来传递光的亚力克，以及拜耳聚碳酸酯有限公司的LD板材都是最大限度缩小灯箱深度的最佳选择。了解所用到的原料和表面材质，以及光学特质是很重要的，既可以确保这个标识能达到大众所期盼的效果，又可以减少材料制造过程的总成本。
It is generally understood that standard white translucent acrylic typically does a better job of “diffusing” the light versus polycarbonate. This feature and its lower overall cost has made acrylic the most common material of choice for outdoor channel letter signs. Sign grade acrylic is available in a range of colors and different types of white.
通常人们认为标准白色的半透明亚克力比聚碳酸酯更适合传播光线。这种特性以及它更加低廉的成本，使得亚克力成为室外标识牌最常用的材料。用于标识牌的亚克力有许多颜色可选，还有不同种类的白色。
The two most popular white acrylics are “2447” and “7328”. 2447 acrylic lets about 50 percent of the light pass through, while 7328 blocks about two-thirds of the light. This means that a sign with a 2447 face will be about 50 percent brighter using the same LEDs. However, 2447 can show more hot spots and looks more “dull” during the day. Therefore, 2447 is ideal when a colored vinyl film is applied over all or part of the sign face and when maximum light transmission is desired.
两种最常用的白色亚克力分别是“2447”和“7328”。2447亚克力可以让二分之一的光线通过，而7328亚克力则挡住了三分之二的光线。这就意味着，使用了2447亚克力在表面的LED指示牌的亮度要高出50%。然而，2447亚克力在白天的时候能显示出更多的热点，并且看起来更柔和。因此，当标识牌的表面全部或部分涂上了彩色乙烯基薄膜，并且想要获得最大的光传导效果时，2447亚克力是最理想的选择。
This brings us to the subject of films. A number of manufacturers produce vinyl films that can be applied to channel letters for a variety of purposes. First and foremost, vinyl films are a flexible way to create a large array of color options and multiple color matching options versus colored acrylic. These translucent films can be applied to a clear or white translucent face, allowing for a large pallet of color options.
这会给我们引入薄膜这个主题。出于各种各样的原因，厂商生产的乙烯基薄膜被大量应用到发光字上。居于首位的原因是由于，乙烯基薄膜是一种可塑性极强的材料，且与彩色亚克力相反的是，它可以创造大多数颜色之间的组合与搭配。透明薄膜能够应用到透明表面上去。
One application example is when translucent vinyl is applied over a white plastic letter leaving a border. In this case, the sign will have a colored center with a white outline trim. This white border creates a more readable sign at night (especially with blue and certain other colored letters).
生活中有大量例子可以说明，透明的乙烯基薄膜应用在发光字上，并且位于白色板材的中心位置。在这种情况下，这个标识的中心是彩色的而周边轮廓是白色的。这种有着白色边缘的标识会在夜晚更具识别性（特别是蓝色或其他颜色的发光字）。
Opaque vinyl films can be placed over the channel letter face to create a certain color during the day and a skeleton outline at night. However, the most common use of opaque vinyl films are modified with small holes - called “day/night” films. Often the daytime color of the sign must be different from the night color. For instance, light colored buildings may need a darker face color during the day (like black) but a white illuminated color at night. This is accomplished by the use of a day/night vinyl which is an opaque vinyl film with transparent “holes” that let a portion of the light pass through the film. Using this approach, one can use white LEDs with a white plastic and a day/night film on the outside and a translucent vinyl on the inside to essentially create any two combinations of different colors during the day and at night.
不透明的乙烯基薄膜能在发光字的表面创造某一特定颜色，白天可以通过薄膜创造出颜色，而晚上就会在骨架轮廓上发光。然而，最普通的不透明乙烯基薄膜被我们制作成的日夜都可以发光的薄膜，它的表面有着小的孔，且在白天、夜晚呈现出的效果是不一样的。例如，表面浅色的建筑在白天的时候需要深色的照明颜色（例如黑色），但是在晚上最好用白色的照明颜色。日夜乙烯基的原理是，不透明的乙烯基薄膜有着透明的“孔”，允许一部分光通过薄膜。用外部是白色板材而内部是透明乙烯基的LED，可以在白天和夜晚，创造两个不同的颜色的组合。
For shallower letters, a number of manufacturers also make diffuser films. These films can be applied to the inside of the plastic face to spread the light more evenly and reduce hot spots in LED illuminated signs. These films work by having suspended particles that change refractive index and redirect or scatter the light. Diffuser films are particularly useful in low-profile channel letters that are less than 3” deep.
在利用浅色发光字时，许多厂商也使用散射薄膜。这些薄膜能够应用在LED发光标识内部，来更加均匀的散布光和减少热点。这些薄膜以悬浮微粒为动力，来改变光的折射率和折射方向，使其散布开来。薄膜扩散器用在深度低于3英寸较小的轮廓发光字上 。
To wrap it up, it is important to understand that the material choice of a given sign project depends on a number of factors, including illumination levels, durability, cost and appearance. The evolution of plastic faces and light management films has evolved alongside LED lighting to open up a broader range of colors, configurations, and new profiles that can give you and your customer new options for their next set of channel letters.
总之，你必须知道给一个标识选择材料是取决于多方面的，包括照明级数、耐久性、价格及外观。板材表面与浅色薄膜的发展脚步已与LED灯齐驱并进，以便在颜色、构造、外观方面获得进一步发展，而这也将为您及您的客户带来更宽泛的选择。
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