A recent market study by Venture Development Corp. reveals the North American market for linear displacement sensors including encoders, linear variable differential transformers (LVDTs), laser systems, magnetostrictive, potentiometers, capacitive, inductive and ultrasonic products totaled $339 million in 2006. VDC says the largest market for LVDTs is for military/aerospace applications. These devices do well in harsh environments; they have only one moving part and little friction between the moving ferromagnetic core and the cylinder in which it moves.
LVDTs are used in automation machinery, civil/structural engineering, power generation, manufacturing, metal stamping/forming, OEM, pulp and paper, industrial valves, R&D and test and automotive.
National Instruments says be mindful that LVDTs might operate at excitation amplitudes and frequencies other than those listed by the manufacturer. Also, stay within the recommended travel specification of your LVDT, and beware of excitation-signal cross-talk between channels.
A tutorial from Macro Sensors lists several other reasons why you should consider LVDTs. They include infinite resolution, over-travel damage-resistance, single-axis sensitivity, separable coil and core, null-point repeatability, fast dynamic response and absolute output.
These sensors find extensive use with pneumatic and hydraulic cylinders and are particularly useful for long strokes. Growth of these sensors is expected to be at an above-average rate over the next five years, with the highest growth-rate expectations for use in metalworking, assembly/robotics equipment and valve applications.
The highest growth rates in the VDC study are for laser systems at 10% and capacitive linear displacement sensors at 8%. The markets for both are small, but each is expected to grow since users are seeking higher accuracies, which these provide. This is particularly the case in the semiconductor and electronics industries, where more precise measurement capabilities enable shrinking the size of electronics.
Tru-Vue photoelectric background-suppression sensors have a 50-mm sensing range and deliver target detection regardless of target color and reflectivity, with detection unaffected by shiny background objects, and eliminate the expense and installation of reflectors or through-beam alignment. They have a 4-in-1 output that automatically detects the connected load and sinks or sources.
|Cylinder Position Sensor|
BIM-UNT universal magnetic-field sensor detects the position of a piston on standard pneumatic cylinders via magnetoresistive, board-level technology and has a sensing face in the front of the sensor to help detect short-stroke cylinders. The sensor comes with a quick mount tab that helps seat the sensor in the cylinders groove
E3X-DAC white LED fiberoptic sensor detects true colors in marks and workpieces independent of light intensity and sensing distance variations. The 10-mm-wide amplifier unit processes color detection through an RGB light-receiving element. One-touch teaching simplifies setup for high-speed packaging and sorting, and electronics packaging including small parts and fine wires.
SA1-RTD surface-mount temperature sensor mounts on flat or curved surfaces and provides Class A accuracy. Based on a 2x2x0.8-mm thin-film platinum RTD and supplied in PFA-insulated 3 or 4-wire configurations in 1, or 3 m lengths or custom lengths with self-adhesive backing or permanent mounting, the RTDs can be used for monitoring motor and transformer core heat and test insulation capabilities.
ACT current transducers, in split and fixed-core models, have jumper-selectable current inputs and 4-20 mA or 0-10 Vdc outputs. Split-core models make using portable data loggers easier, and simple connection enables power consumption or other motor status display. For safety and to eliminate voltage drop, the output is magnetically isolated. The devices are UL, cUL and CE approved.
S51 18-mm sensors in through-beam, retro-reflective, polarized retro-reflective and diffuse modes have a flat, cylindrical housing that offers mounting choices using traditional 18-mm locking nuts or by direct-mounting with two-through holes. The mounting-hole configuration makes it possible to replace many non-threaded sensors. S51 sensors have a sensitivity adjustment and a variety of output configurations.