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Capacitive and Inductive Sensors
Capacitive sensors will detect both metallic and none metallic objects.
None contact capacitive sensors work by measuring changes in an electrical property called capacitance. Capacitance describes how two conductive objects with a space between them respond to a voltage difference applied to them.
One of the major advantages of the capacitive sensors is the ability to detect all material types from metal to plastic to wood, and in some cases it gives the ability to sense through the 'walls' of containers, or to ignore small amounts of product on the sensor face its self.
Inductive sensors will detect on metallic targets.
For non-contact detection of metallic targets at ranges generally under 50mm (2 inches). Inductive proximity sensors emit an alternating electro-magnetic sensing field. When a metal target enters the sensing field, eddy currents are induced in the target, reducing the signal amplitude and triggering a change of state at the sensor output.
Advantages of inductive proximity sensors include insensitivity to water, oil, dirt, non-metallic particles, target colour, or target surface finish, and the ability to withstand high shock and vibration environments.
Inductive sensors are available in sizes from 3mm dia upto 30mm dia, with sensing ranges from O.6mm upto 40mm. The larger the sensor the larger the field and hence the increase in sensing distance. | |
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