
Proximity Sensors

Proximity sensors are non-contact devices that detect the presence or absence of an object using light, sound or electromagnetic fields and transmit that information into an electrical signal. They can be used in industrial and manufacturing industries for inventory management and safety applications. In automated production lines, proximity sensors can be used for object detecting, inspecting, counting and positioning. Four commonly used types of proximity sensors are: ultrasonic, inductive, capacitive and photoelectric.
Ultrasonic proximity sensors consist of an ultrasonic transmitter and an ultrasonic receiver. The transmitter emits a high-frequency sound wave which, when it strikes the object, reflects back to the receiver. The distance of the object is calculated based on how long it took for the sound wave to travel back to the receiver. Ultrasonic proximity sensors can detect solid, liquid and granular objects.
Inductive proximity sensors utilize an electromagnetic field to detect the presence of metallic objects. When a metallic object enters the electromagnetic field, the inductive characteristics of the metal changes the field’s properties, alerting the sensor of the object’s presence. Inductive proximity sensors can only detect metallic objects.
Capacitive proximity sensors utilize the electrical property of capacitance and the change of capacitance in the electrical field around the face of the sensor to detect the presence of an object. They can detect solid, liquid or granular objects.
Photoelectric sensors are devices that use visible or infrared light to detect the presence of an object or its distance from the sensor. Photoelectric sensors consist of an emitter that sends the light and a receiver that receives the light. When the emitted light is interrupted or reflected by an object, it alters the amount of light that arrives at the receiver.
Products
Limit switches are electromechanical switches that operate based on the movement or presence of an object. They are designed to detect the presence of an object using an actuator connected to a series of contacts to detect the presence and proximity or absence of a material or object. When the switch’s actuator is moved by an object it will change the state of an electronic contact set. This movement signals that some preset limit has been reached. There are many different ways a switch can be actuated depending on the type of switch that is being used. Some use a roller and lever, some use a button or plunger, while others might use a rotating arm and rod attached to the main body of a switch. The type of switch that is used will largely be dictated by the specific application.
Where are limit switches used? Limit switches can be used to tally or count items, so that when a limit is reached, the switch will open or close. This open and closing action can be counted by a controller allowing the action to be totalized. Limit switches can be used as safety interlocks to prevent machine parts from moving any further when specific point is reached. Limit switches are also commonly used in larger control systems. For example, when a certain limit is reached, the actuator can deactivate or activate a device to prevent it from malfunctioning.