	Displacement Sensors

Glossary

Resolution

Even when detecting a stationary target, analog output voltage fluctuates slightly due to internal noise. The amount of fluctuation is called resolution; the smaller the fluctuation, the better or higher, the resolution.

Example: 0.1% of F.S.
The minimum readable measurement is 1/1000th of the measuring range.

Linearity

Analog voltage output from a displacement sensor increases in proportion to the distance. The relationship of analog output voltage to distance is ideally represented by a straight line. However, actual measurements deviate from this line. Linearity is the tolerance range in relation to the ideal line, and is indicated as a percentage of F.S. (Full Scale)

Measurements obtained by digital signal processing are slightly different from actual displacement. In this case, linearity refers to the ratio of this difference to the measurement range.

Response frequency for analog output

When measuring a revolving or oscillating target, the displacement sensor fails to respond to the actual displacement speed (or frequency), causing a decrease in analog output level. The response frequency is defined as the frequency when the analog output level is 3 dB lower (at approximately 70%) than the stable level.

The response time for analog output denotes the time required to obtain 90% of the final stable output for quickly-displacing targets.

Temperature drift of analog voltage output

The analog output voltage fluctuates according to ambient temperature. This fluctuation range is called temperature drift and it is determined based on voltage fluctuations per 1°C.
(Example) ±0.03% of F.S./ °C（F.S.＝1V）
0.03% of F.S. per 1°C. In other words, fluctuation per 1°C was 0.3mV.

Reference distance

The distance from the light-emitting surface of the sensor head to the center of the measurement range. At the reference distance, the analog output voltage and the display or measurement value are 0 V.

Operating distance

Displacement meter sensor heads (LC Series) have a stepped reference face. For these meters, the reference distance is the distance from the reference face to the point at which the display or measurement value is 0 V. The distance from the light-emitting surface of the sensor head to the center of the measurement area is called the operating distance.

Zero adjustment (range)

Zero adjustment shifts the actual output voltage (shown as a solid line) in either the positive or negative direction. It is called zero adjustment because it is mainly used for applications where measurement is displayed relative to 0 V preset with a reference target. The range where zero adjustment is possible is called the zero adjustment range.

Configuration of Zero adjustment (range)

Span adjustment (range)

Span adjustment changes the ratio of the output voltage (displacement) to the distance. As shown, the actual voltage-distance relationship (shown as a solid line) can be shifted to either a higher output voltage at the same distance (A) or a lower output voltage at the same distance (B). Span adjustment is used to adjust the level of the output voltage if the above-mentioned ratio is not 1:1 due to a change in target color or material. The span adjustment range is the ratio of the measurement indication to the original output voltage.

Configuration of Span adjustment (range)

	Page Top

Copyright(c) 2010 KEYENCE CORPORATION. All rights reserved.	\| Privacy \| Terms of Use \| Contact \| Produced by