Technical Guide for Displacement Sensors

1. Requirements to Be Confirmed


Category Item Description
Measurement Purposes  
Object Color Reflection rate, Transparency, Opaque, etc.
Dimensions To fit within a measurement range
Tilt Measurement on a tilted surface could be unstable.
Surface Condition Measurement on a rough surface could be fluctuated.
Accuracy Repeat Accuracy, Resolution  
Linearity  
Environment Temperature  
Ambient Light Caution is needed under direct sunlight or strong light.
Production Line Transfer Speed  
Tact Time  
Interface Input for Trigger
Output Control, Analog and Communication

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2. Selection Flow

❶ Select a model for a measurement distance.

  • Select a model for an installation distance, measurement range and object dimensions.

❷ Select a model for object conditions.

  • Select a specular reflective model for transparent or specular object or a diffuse reflective model for others.

❸ Consider a required sampling period.

  • For measurement on a high-speed transfer line select a model that supports a short sampling period.

❹ Consider a required measurement accuracy.

  • Select a model to meet required measurement accuracy.
    Compared with a required accuracy, 10 times of a sum of linearity and repeat accuracy is a guideline for selection.
    As the moving resolution varies among objects, testing with actual samples is highly recommended.

    〈Calculation of Linearity〉
    Linearity = +/- percentage x full scale

    〈Calculation Example〉
    A Model with Linearity of +/- 0.1% and Full scale of +/- 20mm
    = +/- 0.1% x +/- 20mm
    = +/- 0.1% x 40mm
    = +/- 0.04mm = 40μm

    Shorter the distance between a laser displacement sensor and measurement object is, higher accuracy the measurement results will be.
    If the required accuracy cannot be obtained, consider again a model in the same series with a shorter measurement range or a model in the higher series with a higher accuracy.


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