Short- or long-range photoelectric sensors for precise distance measurement

Contrinex 6/21/2017

Photoelectric Sensors For Distance MeasurementAs contactless measurement devices, photoelectric distance sensors are suitable for numerous areas of application. Different operating principles are available, depending on the distance to be measured. The specialists at Contrinex use a laser triangulation method for highly accurate distance measurement at short ranges, while at long ranges they prefer the optical time-of-flight (TOF) method. These measuring technologies are used by two new high-precision sensors: DTL-C23 for short range distance measurement and DTL-C55 for longer distances. With both sensor types, distance measurement is largely independent of target color or surface characteristics and repeatability is high. Detected distances can be output via an adjustable analog output and, for a digital output, a switching window of acceptance may be configured by teach-in. The sensors operate at ambient temperatures from -20 to +60°C (-4 to +140°F) and are extremely water-resistant with an IP67/IP69K enclosure rating. DTL-C55 sensors also have Ecolab certification, being highly resistant to industrial cleaning agents and therefore ideal for hygienic areas.

Precise short-range measurement

The DTL-C23 distance sensor operates according to the principle of laser triangulation and, depending on the type, measures distances of 20 to 100 mm at a resolution of 0.12 mm and linearity of +/- 0.25 mm. With a measuring point diameter of only 1.5 mm, repeatability is <0.25 mm at a distance of 80 mm. A typical application is measuring the thickness of material on winding rolls. By setting the range of the 1 to 10 V analog output to the start and end thicknesses, optimum resolution can easily be obtained. This compact sensor is also suitable for small-part detection and checking of position, height or thickness.

Longer distances measured and transmitted directly in digital form

The new DTL-C55 distance sensor uses the optical TOF method to measure distances up to 5000 mm. In the IO-Link version, measurements are passed directly to the control system as millimeter values in digital form, with no need for an additional analog-to-digital converter and no signal drop for long lines. The IO-Link Smart Sensor Profile simplifies handling and minimizes integration cost. This profile also supports initial setup of sensors with user-friendly standard parameters and teach functions. Existing control system parameters are transferred to each newly installed sensor via the bus. In addition, IO-Link provides comprehensive diagnostic options and additional information such as operating hours, signal quality or the number of switching operations. With two virtual switching points settable either via teach-in or direct parameter write-in, the sensor is particularly suitable for use in mobile logistics. For example, on forklift trucks its long measurement range will reliably detect goods already on shelves and measure any free space for more items, ensuring full utilization of storage.