Topic: Presence Sensing

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Microscan's QX Hawk Code Reader Simplifies Track-and-Trace Implementation
High-Performance Reader Has Flexibility to Read Any Mark at Any Distance

Seeing the Learning Curve in Color
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Simplicity Is the Aim in First Color-Sensor Installation

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White Papers: In Depth Research

Laser Displacement Sensor Technology Book
Author: KEYENCE
Posted: 02/08/2010
Innovative Measurement Accuracy and Stability

A laser beam emitted from the semiconductor laser is applied to the target. The light reflected from the target is collected by the receiver lens and focused on the light-receiving element. When the distance to the target changes, the angle of the reflected light passing through the receiver lens changes, and the light is focused at a different position on the light-receiving element.

The measurement accuracy of the laser sensor utilizing triangulation is greatly affected by the following two factors:
Optical design and Stability of received light intensity and waveform.

With a single receiver lens, the spot diameter formed on the light-receiving element becomes larger when the measuring distance is shorter or longer than the reference distance, due to the lens aberration. When the spot diameter on the light-receiving element becomes larger, the measurement accuracy factors, such as "resolution", "linearity", and "scan resolution", become poorer than those obtained at the reference distance. Consequently, it is necessary to develop an optical design which ensures a constant spot size regardless of the measuring distance.

As described in "1. Basic principle of triangulation", a laser displacement sensor calculates the distance to a target by focusing the light reflected from the target on the light-receiving element. If the light reflected from the target changes due to the color, gloss, surface condition (roughness, tilt) of the target surface, the condition of the beam spot formed on the light-receiving element (received light waveform) also changes. Such a change in the beam spot condition (received light waveform) affects the measurement accuracy of laser displacement sensors.

Membrane Potentiometers Simplify Position Sensing
Author: Guido Woska
Posted: 10/20/2009
Ultra-flat design enables smart engineering and cost-saving applications.

Membrane potentiometers have c hanged the way engineers think about sensing. With some measuring only 0.5mm [.05cm]thick, ultra-flat membrane potentiometers feature comparable product characteristics to conventional potentiometers, but are liberal with design freedom at significantly lower costs.

Today's membrane potentiometers can be used in the same applications as conventional potentiometers, but can also fit into space-constrained areas. In this case, function can follow form an uncommon feature of mechanical potentiometers.

Because most producers of membrane potentiometers offer customized products with only small tooling efforts, costs are very competitive, even for small prototype quantities. Three additional advantages are found in the basic construction of the membrane potentiometer: its ability to be fully sealed; the possibility of a hollow shaft design; and numerous wiper options, including operation by hand.

Most membrane potentiometers, like the Sensofoil products, c an be sealed at up to an IP65 (NEMA4x) rating and beyond. Conventional potentiometers require a difficult assembly of the wiper, particularly in a hollow shaft assembly. The hollow shaft design of membrane potentiometers, as with Sensofoil , is more reliable and cost efficient. Because of the simple nature of the membrane potentiometer, such technical adjustments are not required. The wiper for the membrane potentiometer c an be as simple as a small plastic knob sliding across the surface; it requires no external electric al contact. Most membrane potentiometers c an also be operated by sliding a finger over its surface, and Sensofoil is even available in a contactless magnetic version.

Color Contrast and Luminescence Sensors
Author: EMX Industries, Inc.
Posted: 02/06/2008
Taking the mystery out of selecting the right photoelectric sensor for your application

Proximity sensors in harsh-duty environments
Author: Turck
Posted: 07/14/2006
Taking the time to investigate which sensors and corresponding components are best suited for particular environmental conditions can save time and money in the long run, as well as ease troubleshooting and maintenance issues. So how do you find the right sensor?

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