Color Mark Sensor is frequently used to identify a spot on a given color or item, and then a comparison is done with a non-color standard area to accomplish color standard detection rather than direct measurement of color. This is a top class product, which is also known as a reverse device. The important point is that in this color mark sensor, the installation of the light source is done in a perpendicular direction to the target object and the receiver which is installed at an acute angle to the object.