邦纳BANNER测量过量增益实操

什么是过量增益?

过量增益是传感器可靠检测所需最小光通量的估计方法。

The light signal that your sensor emits is factory-calibrated to a certain level of performance. However, contaminants in the sensing environment such as dirt, dust, smoke, and moisture, can cause signal attenuation.  Excess gain may be seen as the extra sensing energy available to overcome this attenuation.

测量过量增益
过量增益能够用如下公式来表达。

过量增益 =接收器接收到的光能量 /使传感器动作的阈值。

这个阈值是传感器的放大器所需求的光能量，使得传感器的输出发作改变，比如从Off切换到On，或许反之。 
过量增益为什么对光电传感器很重要
An excess gain curve, an important part of every photoelectric sensor specification, is plotted on an x/y axis. It shows the excess gain available for a particular sensor or sensing system, as a function of distance.  Excess gain curves are plotted for conditions of perfectly clean air and maximum receiver gain. 

重要的假定
关于凭借过量增量值优化检测的可靠性，有几个假定。

Use as high an excess gain setting as possible, without compromising target detection. In most sensing situations, excess gain correlates directly to sensing reliability.
挑选一款适宜的传感器，使得其过量增益适合使用需求。
 
excess-gain-charts-polarized-vs-non
曲线: 过量增益曲线，举例 QS18 光电传感器 反射板式。 

怎么凭借过量增益挑选最适合的传感器
过量增益 (EG) 一般情况下
1.5x 洁净的环境: 镜头、反射板上没有尘埃 
5x 轻微尘埃: 轻微 堆积 尘埃等，在镜头或许反射板上。
10x 中等尘埃的环境 在镜头上有显着的尘埃等污染，或许 反射板上
50x Very dirty: Heavy contamination on lenses. Heavy fog, mist, dust, smoke, or oil film.  Minimal cleaning of lenses,
假如大体了解检测的环境，能够把过量增益作为参阅，以确保传感器的光通量不会衰减至无。

这些参阅要素包含，纤细的检测变化，例如传感器没有对准，检测环境的纤细变化。

洁净的环境 - 1.5X 过量增益 (EG)
For a perfectly clean operating environment, an excess gain of 1.5x (50% more energy than the minimum needed for operation) is suggested. Some environments that have "clean air" are those found in the semiconductor or pharmaceutical industries. In these environments, no dirt builds up on the sensor lenses or retroreflectors.

轻微尘埃的环境 - 5X 过量增量
An office or a clean factory might be characterized as a "slightly dirty" environment. This means sensor lenses or retroreflectors may experience a slight build-up of dust, dirt, oil, or moisture. Lenses are cleaned on a regular schedule. In a "slightly dirty" environment, the excess gain should be 5 times more than what is minimally required for sensor operation.

一般尘埃的工作环境 – 10X 过量增益
In a "moderately dirty" environment, obvious contamination can be seen on lenses or retroreflectors. These environments are also likely to have periodic washdowns. "Moderately dirty" environments can be found in heavy industry, food processing, or the automotive industry. For such environments, Banner recommends an excess gain 10 times more than what is minimally required. 
重度尘埃– 50X过量增益
Some environments like those found in foundries, mining operations, tile ovens, and outdoors are considered "very dirty." This is because lenses and retroreflectors become heavily contaminated, and are subject to minimal cleaning. There may be heavy fog, mist, dust, smoke, or oil film in the environment.

然而有一点需求注意，假如过量增益超过50倍，则传感器可能会穿透纸张或许类似密度的原料。
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