One key component in a channel letter is the return. The return is the letter’s metal side structure, as shown in the diagram below.
字边条是指发光字的金属边结构，是发光字的一个重要组成部分。如下图所示。
Returns are available in differing depths ranging from two to eight inches, with five inches being the most common. However, three-inch letter returns are becoming more popular and have several potential uses and benefits. This article briefly reviews some of the considerations involved with using three-inch returns on channel letter signage.
字边条的尺寸范围从2-8英寸不等，最常见的是5英寸。不过，3英寸由于其潜在优势变得越来越受欢迎。这篇文章主要介绍：在发光字标识领域，使用3英寸字边条时的注意事项。
WHAT ARE THE PURPOSES OF A LETTER RETURN? 不可小觑的小小字边条
A channel letter return has several purposes. First, it creates the actual enclosed “channel” from which this signage type is named. In addition, the return also provides the physical protrusion of a letter set. This projection provides channel letters with an additional level of visibility lacked by flat signage.Third, the return both provides the LED mounting area and encloses the light chamber that focuses the illumination on the letter face (or the back if the channel letters are reverse-lit.) .So the return is an important multi-purpose letter component.
字边条的重要性体现在三个方面。首先，它创立了封闭式引导标识类型----发光字。此外，使用字边条后可使发光字周边凸起变得显眼。第三，字边条部分可提供LED安装面积，且让内部灯光聚焦在发光字表面（或者发光字背面）。以上便是字边条不可小觑之处。
CHANNEL LETTER ILLUMINATION 3英寸字边条脱颖而出
One initial consideration with the use of a three-inch return is the illumination requirements. Successful illumination of a letter face on a three-inch return requires a different LED viewing angle than does a five-inch return.
最初选择3英寸字边条是出于照明效果考虑的，因为不同的发光角度呈现在发光字表面的照明效果也是不同的，结果显示字3英寸边条比5英寸效果要好。
Here is a diagram of the same LED viewing angle used in both a five-inch and a three-inch return – note the difference in the photo below.
这里有两张图片，是在发光角度相同的前提下，3英寸字边条和5英寸字边条的对比图---请注意下方这张图片的差异。
The three-inch return does not provide as broad an illumination area, so a wider LED viewing angle may be needed. A viewing angle that is too narrow may result in “hot spots.”
3英寸字边条照明范围不是很广，这可能会导致“易燃”，所以我们需要更宽的LED发光角度。
MATCHING COMPONENT PROJECTION 相得益彰的投影组件
A second consideration regarding three-inch returns is their ability to ensure that all components of a given sign structure have an equal projection from the building façade.
在字边条使用过程中，要确保所有的标识结构组件在建筑表面的投影是平行的，不要出现投影参差不齐的情况。
For example, a channel letter set may have one separate component (such as a logo box) that has an eight-inch protrusion. But suppose a second component of that same sign structure is a raceway mounted channel letter set.The raceway alone has a five-inch depth, so if the overall sign structural projection (8”) is to match the logo box projection it must protrude only three more inches from the wall. Using a standard five-inch return would mean these two sign elements would have differing mismatched protrusions (which has an unprofessional appearance.) Specifying a three-inch letter return may solve that issue.
举个例子，发光字标识牌凸出8英寸（比如LOGO框），假设其中一个组成部件用了管道安装发光字装置，管道深度有5英寸，要怎么做才能使投影相匹配呢？答案是：只要从墙上再凸出3英寸，就可以使整体的标识结构投影（8英寸）与LOGO框投影相匹配。不过使用5英寸的字边条就意味着，这两个标识投影不在一个平面上，至少从外观上看起来很不专业。但是3英寸的字边条就可以解决这些问题。
CHANNEL LETTER DESIGN 宽度选择中的大学问
The physical letter design is another consideration in your selection of a channel letter return depth. If your customer’s design calls for a serif font that has tight channel areas (or is an “artistic” font with curved letters), keep in mind that such an arrangement opens up the possibility of non-optimal letter illumination when using five-inch returns. That is because LED module installation and placement is more difficult as the return channel becomes smaller (as it sometimes does in serif or “artistic” font designs.)
关于发光字设计需要注意的是：字边条宽度的选择。如果你的客户要求使用衬线字体（或者是折弯发光字使用“艺术字”字体），不要选择5英寸字边条，这会增加LED模组安装的难度而且发光字会变小。
Specifying a three-inch return can be helpful. This return depth poses less of an impediment to LED module installation, even in tight letter areas. Corners and crevices inside a return are more easily reached when an installer is working with a three-inch return.
反而选择3英寸的字边条就会很完美的解决，它会连角落和缝隙也不会落下而且不会阻碍发光字内部LED组块照明。
EASE OF SERVICE 满意的服务
An additional consideration for three-inch returns is the potential ease of field service. Signage service on a mounted letter set with three-inch returns will typically be simpler than when servicing the same set with five-inch returns.
3英寸字边条有更专业的服务团队。
Just as it was with the initial LED installation, the letter set interior channels are more accessible. So easier channel letter service (and potentially lower service call costs) can be another benefit of using three-inch returns.
3英寸字边条发光字不仅在安装方面如同LED一样便捷，而且高性价比服务也使客户赞不绝口。
RETURN COLOR SELECTION 字边条因“涂一涂”而美好
Color availability is another potential concern with three-inch returns. Three inch is a less commonly specified return depth, so many letter producers do not stock the same selection of colors (this does not mean that a given pre-painted color is not available in three inch. It only means that a channel letter producer is less likely to carry an ongoing inventory of that specific color.)
我们需要考虑字边条颜色的实用性。3英寸字边条宽度不太常见，所以生产商只库存了几种颜色的产品，但这并不意味着只局限于这几种颜色。
For example, at Direct Sign Wholesale the standard three-inch return colors currently stocked are:
· Black
· White
· Bronze
例如，标识批发有限公司（Direct Sign Wholesale）3英寸字边条库存的颜色有：
l 黑色
l 白色
l 古铜色
That is a far smaller assortment than is typically inventoried for five-inch letter returns. “However, if a customer places a large order of letters (50 sets or more) with three-inch returns with a non-standard color, we can order five inch coil and have it trimmed,” says DSW production manager Chris Rogers.
比起5英寸字边条来说，3英寸字边条的颜色真的是少得可怜。标识批发有限公司（Direct Sign Wholesale）生产经理克里斯·罗杰斯说，“不过，如果客户订了大量3英寸字边条的订单（50套以上），我们可以修剪5英寸字边条顺便利用5英寸的丰富颜色。”
For smaller channel letter projects, however, it may be more economical to paint the three-inch return instead of ordering that specific color from the coil manufacturer. Either option will mean an additional cost to your customer, but painting may be less expensive choice than ordering a pre-painted custom three inch return color.
反之对于少量的订单来说，如果选择在字边条边缘涂色，成本会比订制特殊的颜色低很多。对于客户来说，订制会增加额外的费用，这么一来，涂色便是最合适的选择。
MINIMUM LETTER SPECIFICATIONS 标识世界的小矮人---迷你发光字
Another variable that may be impacted by the return specification is the minimum letter size (or the “minimum spec” – the smallest vertical letter size a producer is willing to fabricate.) For instance, at Direct Sign Wholesale the minimum letter height is eight inches.
迷你发光字有可能影响字边条规格（有生产者在制造超级迷你的立式发光字。）比如，标识批发有限公司（Direct Sign Wholesale）的迷你发光字高度只有8英寸。
However, a three-inch return specification may change the minimum permissible letter specification to a smaller vertical amount. So if your customer is requesting an unusually small channel letter size, specifying three-inch letter returns may assist in meeting their project requirement.
然而，对于小的立式发光字来说，3英寸的字边条就适合于迷你发光字规格。所以如果你的客户要求订制小的发光字，3英寸字边条就可以满足他们的项目要求。
LETTER SET WEIGHT 发光字重量中的奥秘
Letter set weight is another consideration with the three-inch return depth. A substantial part of a channel letter set’s bulk comes from the weight of the returns. Removing two inches from that component reduces the letter set weight.This can be helpful when the installation of a three-inch return letter set is planned. A lighter letter set means an easier sign placement and positioning on the wall. It may also mean that a one-person installation is possible instead of using two people.This weight difference also may mean a shipping cost decrease .
发光字装置重量问题也是必须要考虑的，字边条的重量占了很大比重，如果宽度减少便可减轻重量。所以3英寸字边条的发光字装置符合重量标准，一个人完全可以妥善安装，同时重量的减轻也意味着运输成本降低。
SPECIFIED RETURN 无规矩不成方圆
Permitting is another consideration when the depth of the channel letter return is specified. As mentioned before, a shallower return reduces the protrusion from the building facade. Some cities have ordinances specifying a maximum permissible sign projection distance. Five-inch returns may cause your customer’s sign to project further than is allowed under city permitting law (particularly when the letters are raceway mounted.)
最后需要注意的是，字边条宽度是有规格限定的。就像之前提到的，在管道安装发光字装置情况下，要减少建筑物表面的凸出。一些城市法令规定了标识投影的最大值，5英寸的字边条可能会导致投影远远超过城市法规所允许
