Photoelectric Switch Reliable And Appropriate Use
Photoelectric Switch (photoelectric sensor) is the abbreviation of the photoelectric proximity switch, it is the use of objects to detect the beam or reflection, by the synchronous loop gating circuit, thus detecting the presence of objects. Objects are not limited to metal, and all objects that reflect light can be detected. The Photoelectric Switch converts the input current into the optical signal on the transmitter, and the receiver detects the intensity of the received light or the presence or absence of the target object. Security system commonly used in the Photoelectric Switch smoke alarm, the industry often use it to count the number of arm movement.
Photoelectric Switches have been used for level detection, level control, product counting, width discrimination, speed detection, fixed length cutting, hole identification, signal delay, automatic door sensing, color detection, punch and shears Security and many other areas. In addition, the use of infrared hidden, but also in the banks, warehouses, shops, offices and other needs of the occasion as an anti-theft alert.
3 working principle
The diagram on the right shows the working principle of the reflective Photoelectric Switch. In the figure, the modulation pulse generated by the oscillation circuit is reflected by the circuit, and then use the digital integral Photoelectric Switch or RC integral way to remove the interference, and finally by delay (or no delay) to trigger the driver output Photoelectric Switch control signal.
The use of optical components in the middle of the media to make changes in the beam; the use of light to reflect the object; the light beam after a long distance after the instant return. Photoelectric Switch is composed of transmitter, receiver and detection circuit composed of three parts. The transmitter is aimed at the target beam, and the emitted beam is typically derived from a light emitting diode (LED) and a laser diode. The beam is emitted continuously, or the pulse width is changed. The radiation intensity of the pulsed modulated beam is selected several times during the launch and runs unobstructed towards the target. The receiver consists of a photodiode or a phototransistor. In front of the receiver, there are optical elements such as lenses and iris. Behind it is the detection circuit, which filters out the effective signal and applies the signal.
An optocoupler is an electro-optical-electrical conversion device that transmits electrical signals in the form of light. It consists of two parts: the light source and the receiver. The light source and the light receiver are assembled in the same enclosed case and are separated from each other by a transparent insulator. The source of the light source is the input terminal, the pin of the receiver is the output terminal. The common light source is the light emitting diode, the photodiode is the photodiode, the phototransistor and so on. There are many types of optocouplers, common photodiode type, photoelectric transistor type, photoresistor type, light control thyristor type, photoelectric Darlington type, integrated circuit type. The principle of working at the input of the optocoupler power supply signal to make the light source light, the intensity of light depends on the size of the excitation current, the light irradiated to the receiver on the receiver, the photoelectric effect produced by the photocurrent, by the light The output of the device leads, so that the realization of a power-to-electrical conversion.
The diffuse reflection type is when the switch emits a light beam, the target produces diffuse reflection, the transmitter and the receiver form a single standard part. When there is enough combined light to return to the receiver, the switching state changes, the typical value of the acting distance is until 3 Meter. Features: the effective role of the distance is determined by the target's ability to reflect, by the target surface properties and color decisions; smaller assembly costs, when the switch from a single component, usually can be achieved coarse positioning; using background suppression function to adjust the measurement distance ; Sensitive to dust on the target and to reflective performance that has changed the target.
The specular reflection consists of a transmitter and a receiver that is a standard configuration in which the light beam emitted from the transmitter is reflected at the opposite mirror, that is, it returns to the receiver and a change in the switching signal when the beam is interrupted. The passage of light is twice the duration of the signal, the effective range of the distance from 0.1 to 20 meters. Features: Identify opaque objects; with a mirror component, the formation of a high range of effective distance; not susceptible to interference, can be reliable and appropriate use in the wild or dusty environment.
The slotted Photoelectric Switch is usually a standard U-shaped structure in which the transmitter and receiver are located on both sides of the U-slot and form
An optical axis, when the object is detected through the U-shaped groove and block the optical axis, the Photoelectric Switch to produce the detected switch signal. Slot-type Photoelectric Switch is relatively safe and reliable for high-speed detection, resolution of transparent and translucent objects.
Fiber optic Photoelectric Switch using plastic or glass fiber optic sensors to guide the light, in order to achieve the detection of objects in the vicinity of the detection area. Optical fiber sensors are usually divided into radio and diffuse reflection.