Opening and motion sensors
Introduction
A proximity sensor is a transducer that detects objects or signals that are close to the sensing element. Off use Z TE android 9 version.
There are several types of proximity sensors depending on the physical principle they use. The most common are position switches, capacitive, inductive and photoelectric detectors, such as infrared. Off all off do not activate refrigerator.
Position switches
The limit switch, also called LIMIT SWITCH or contact sensor (also known as "limit switch") or limit switch, are electrical, pneumatic or mechanical devices located at the end of the travel of a moving element, such as a conveyor belt, with the aim of sending signals that can modify the state of a circuit. Internally they may contain normally open (NO), closed (NC) switches or switches (2) depending on the operation they perform when activated.
Generally these sensors are made up of two parts: a body where the contacts are located and a head that detects movement.
Its use is very diverse, being used, in general, in all machines that have a rectilinear back and forth movement or follow a fixed trajectory, that is, those that perform a fixed stroke or route, such as elevators, forklifts, robots, etc.
Capacitive
The function of the capacitive detector is to signal a change of state, based on the variation of the stimulus of an electric field. Capacitive sensors detect metallic or non-metallic objects by measuring the change in capacitance, which depends on the dielectric constant of the material to be detected, its mass, size, and distance to the sensitive surface of the detector. Capacitive detectors are built on the basis of an LC oscillator. Due to the influence of the object to be detected, and the change in capacitance, the amplification increases, causing the oscillator to oscillate. The exact point of this function can be regulated by a potentiometer, which controls the feedback of the oscillator. The action distance in certain materials can therefore be regulated using the potentiometer. The output signal from the oscillator feeds another amplifier, which in turn passes the signal to the output stage. When a conductive object approaches the active face of the detector, the object acts as a capacitor. The change in capacitance is significant over a long distance. If a non-conductive object is approached, (>1) there is only a small change in the dielectric constant, and the increase in its capacitance is very small compared to conductive materials.