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October 25, 2011 / charliestrobelpewa

Why Sensing Ranges Vary Depending on their Make-up When Using Diffuse Sensing

A diffuse/reflective sensor shines its light onto the sensing object, and detects the object by how strong the light (intensity) is reflected back.

The intensity of the reflected light varies depending on the material, color, and surface condition (evenness, gloss) and such of the sensing object. In other words, detection depends on the object itself.

Correlation between sensing object size and sensing range. – CX-424

 Correlation between sensing object size and sensing range - CX-424

The bigger the sensing object, the bigger the reflection becomes.  However, if the sensing object is exceeding the spread of light and the broad of light receiving field, the sensing range does not get longer.

Correlation between sensing object and sensing range.
This graph shows relative sensing range for different sensing objects has been given taking the sensing range for white non-glossy paper as 100. The values are given for reference.

“Black is 40% of white, aluminum is 3.5 times white, mirror is 8.5 times white.”
This is how I memorized, as a guide. It is advisable to memorize this.

Here are some other material with its relative reflectivity and excess gain.

The sensing range noted in the catalog is the value specified for standard sensing object (mainly white non-glossy paper of standard size). It is necessary to confirm detection with the actual sensing object!


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