One key component in a channel letter is the return. The return is the letter’s metal side structure, as shown in Diagram 1, below.

槽形发光字的一个关键部分是字槽的宽度。字槽就是发光字的金属边结构，如图1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.

字槽宽度从2英寸到8英寸的都有，其中5英寸的是最常见的。然而，3英寸的字槽宽度越来越受欢迎，它有几个潜在的用途和优势。这篇文章简要介绍了制作3英寸字槽宽度的槽形发光字注意事项。

What Are the Purposes of a Letter Return?

字槽的作用是什么呢？

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.

槽形发光字字槽有几种不同的用途。首先，它形成了槽形发光字实际的封闭“槽”。此外，字槽也展示了发光字凸出的结构特点。这种设计为槽形发光字增添了平面标识所欠缺的视觉冲击力。

Third, the return both provides the LED mounting area and encloses the light chamber that focuses the illumination on the letter face (or back if the channel letters are reverse lit.) So the return is an important multi-purpose letter component.

第三，字槽为LED提供了安装位置，并将字槽封闭起来，使得光线聚集在发光字表面（或背面）。因此字槽是槽形发光字重要的多用途组件。

Channel Letter Illumination

槽形发光字照明

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.

最初想到用三英寸宽字槽是为了满足照明需求。要想在三英寸宽字槽中得到完美的照明，就需要将LED以不同于五英寸字槽中LED的视角进行安装。

Diagram 2, below, illustrates the same LED viewing angle used in both a five-inch and a three-inch return—note the difference. The three-inch return does not provide as broad an illumination area, so a higher LED viewing angle may be needed. A viewing angle that is too narrow may result in “hot spots.”

图2清晰明了地显示出五英寸字槽和三英寸字槽中，相同LED视角产生的不同照明效果。三英寸字槽提供的照明区域不够大，因此需要更宽的LED视角。太窄的视角可能会产生“潜在的危险区域”。

Matching Component Projection

组件投影匹配

A second consideration regarding three-inch returns is their ability to ensure all components of a given sign structure have an equal projection from the building façade.

第二个考虑使用三英寸字槽的原因是，它们能够保证所有的标识组件在建筑表面形成均匀的投影。

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.

例如，一个槽形发光字装置可能带有一个单独凸出8英寸的组件（譬如标识框）。假定相同标识结构的第二个组件是槽形发光字的电缆安装轨道。

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.

电缆安装轨道的深度为五英寸，因此整个标识结构要想和标识框八英寸投影相匹配的话，安装轨道只能从墙面凸出三英寸。采用标准五英寸字槽制作发光字意味着这两种方案会产生不协调的凸出效果（展现出一种不专业的外观）。而采用三英寸字槽或许就能解决这个问题。

Channel Letter Design

槽形发光字设计

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.)

在选择槽形发光字字槽宽度时，发光字的物理结构设计也是需要考虑的。如果你的客户要求将狭窄的字槽区域设计成有衬线字体的结构（或用弯曲的字母做成“艺术”字体），那么请记住，这样的设计使用五英寸字槽可能达不到最佳照明效果。因为在更狭小的字槽中安装布置LED模组是非常困难的（因为有时需要做成衬线字体或“艺术”字体设计）。

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 has only a three-inch return to work around.

使用三英寸字槽或许会产生不一样的效果。这种字槽深度使得在狭小区域安装LED模组变得更加容易，并且字槽角落和缝隙处也能很容易地进行安装工作。

Ease of Service

便于维护

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 is servicing the same set with five-inch returns.

另一个使用三英寸字槽的原因是潜在的服务便利性。为三英寸字槽的槽形发光字做维护服务通常会比五英寸字槽的更容易。

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.

因此，发光字维护的便利性（可能会降低维护成本）是使用三英寸字槽的另一个好处。

Open Face Channel Letters

开口槽形发光字应用

Open face channel letter sets offer another potential use of three-inch letter returns. Though the usage of neon illumination has decreased, neon-illuminated open face sets are still periodically specified. For that letter type, a three-inch return will result in a more effective letter set due to more exposure of the actual neon tubes.

开口槽形发光字是三英寸字槽另一种潜在应用渠道。尽管霓虹灯照明的使用率已经下降了，但是用霓虹灯照明的开口发光字仍然定期被指定使用。对于这种发光字类型，由于暴露了较多的霓虹灯灯管，因此三英寸字槽设计会形成更高效的发光字装置。

Return Color Selection

字槽颜色选择

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.)

颜色可选性是三英寸字槽的另一个潜在关注点。一般情况下没有特定颜色的三英寸字槽，因此许多发光字生产商没有相同颜色字槽的存货。（这并不意味着给定的喷涂颜色不适用于三英寸字槽。它只是说槽形发光字生产商不太可能一直都有特定颜色字槽的存货。）

For example, at Direct Sign Wholesale the standard three-inch return colors currently stocked are:

Black , White, Bronze.

例如，目前Direct Sign Wholesale公司的标准三英寸字槽存货的颜色有：黑色、白色和青铜色。

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.

DSW公司产品经理克里斯·罗杰斯说：“这个颜色分类比五英寸字槽存货的颜色分类少得多。然而，如果客户需要大量（50套或更多）非标准色三英寸字槽的发光字，我们可以订购五英寸的特定颜色线圈进行切割裁剪来完成。”

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.

然而，对于较小的槽形发光字制作项目，直接将三英寸字槽喷涂上色比订购特定颜色线圈更经济合算。无论哪种方式，对客户都是一笔额外的花费，但是直接喷涂比订购特定颜色线圈便宜得多。

Minimum Letter Specifications

发光字最小规格

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.

另一个影响字槽规格的可变因素是发光字的最小尺寸（或“最小规格”——生产商愿意制作的最小直立发光字）。例如，Direct Sign Wholesale公司制作的发光字最小为八英寸。

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，三英寸字槽可能会使得发光字最小制作规格变得更小。因此如果你的客户要求制作比正常情况下最小规格还小的发光字，那么特定三英寸字槽或许会满足他们的需求。

Letter Set Weight

发光字重量

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.

发光字重量是使用三英寸字槽又一个需要考虑的问题。字槽重量占据整个槽形发光字重量的很大一部分。减少两英寸的字槽会降低整个发光字的重量。

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.

这对安装三英寸字槽的发光字是有好处的。较轻便的发光字装置意味着易于将其安装到墙上，同时意味着一个人也可以完成安装工作。

This weight difference also may mean a shipping cost decrease (assuming the carrier partially bases their charge on weight.)

这种重量的变化还意味着运输成本的降低（假设送货员是根据重量收费的）。

Permit Issues

许可事项

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 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).

当指定了槽形发光字字槽深度后，就要考虑许可证的问题了。如前所述，较浅的字槽深度会减小与建筑表面之间的距离。一些城市对标识投影最大距离有限制。五英寸字槽标识的投影距离可能会超出城市法律所规定的距离。

Summary

结论

So the return specification has multiple considerations for the successful completion and installation of a channel letter project. The usage of a three-inch return may allow you to meet permitting requirements, specify smaller letter sizes from the manufacturer and make easier field service calls.

因此，字槽规格对槽形发光字的完美制作和安装是很重要的。采用三英寸字槽可能会符合法律许可要求，从而制作出更小规格的发光字，并且使得维护服务更加容易。