Photoelectric Switch Application Of Photoelectric Effect
Photoelectric switch definition: This product to light source for the media, the application of photoelectric effect, when the light source by the object shield or reflection, radiation and shading lead to changes in the amount of light to detect the object's presence, size and brightness, and to produce contact and no Contact output signal of the switching element. The photoelectric switch includes several types, which do not have the light source itself, and is detected by the change amount of the light emitted by the measured object. The illumination of the photoelectric switch by the natural light shields the amount of the change of the natural light from the object; the photoelectric switch itself has the light source, Of the light source to be detected by the object reflection, absorption, and transmission of light to detect the amount of change. Commonly used light source for the ultraviolet light, visible light, infrared light band, light source type bulb, LED, laser tube; output signal switch or analog and communication data information.
Photoelectric switch called, mainly for the switch output switch components.
Photoelectric sensor called, covering the output switch, analog, communication data.
At present, the name of the market photoelectric switch is divided into light source, detection form, use, structure, etc. named.
First, the principle and classification of photoelectric switch
1: Classification by test form
(1) on the radio
The emitter is arranged by a transmitter opposite to a receiver. The light emitted by the emitter is directed to the receiver, and a closed optical path is formed between the transmitter and the receiver. The light is blocked by light or the light is attenuated Detection of a form of detection. This type of test takes a long distance, but requires a transmitter and requires power distribution; in some applications such as space is small, improper distribution of the use of more trouble.
② transmitter and receiver integration, optical transmission for the DC mode of non-modulated signal, the main small gap photoelectric switch, such as U-type, C-type slot photoelectric switch.
(2) direct reflex
In this way, the transmitter and receiver are integrated, and the light emitted by the emitter is directly irradiated to the object to be detected and detected according to the change of the reflected light. Can be said to be similar to the eyes of a detector. And the role of the radio compared to the relatively short distance, only a single line can be distributed, are common detectors.
(3) mirror reflection type
In this way, the transmitter and receiver are integrated, the photoelectric switch is opposed to the anti-angle matrix mirror, the emitter light is reflected back to the receiver, the photoelectric switch and the angle matrix mirror (polygon mirror) Optical path, through the light path of the light is blocked or light attenuation to detect a form of detection, the detection of the role of the distance than the shooting short, longer than the direct reflex. Only need to single-line distribution can be, because the use of reflective mirror optical axis adjustment than the radio-type easy; mirror by the multi-prism angle matrix plate or glass-ceramic particles reflective film.
(2) a reflector-type photoelectric switch with MSR function, if the object is flat and shiny, it will produce a malfunction, to solve this problem, you can use MSR function, its main working principle is based on angular matrix reflector can make The direction of the polarized light is changed by 90 °, and the polarized light diaphragm is placed in front of the double lens, so the angle matrix reflector is used and the optical path is closed. If the object of a plane mirror or reflector ratio (such as a glass bottle, etc.) can not change the direction of polarization, the reflected light from which it is blocked can not enter the receiver, so it can be easily detected, thereby solving the problem And it causes a malfunction.
(4) Radiation detection form
By detecting the light emitted by the object to be detected. Such as the use of the iron and steel industry for the heating of the infrared radiation emitted by the detection of the photoelectric switch.
(5) limited reflection type
This is the transmitter and receiver are integrated, the transmitter and receiver to form an angle, the optical axis of the optical axis and the receiving optical axis of the best cross-regional sensitivity.
In this way the transmitter and receiver are integrated, the transmitter and receiver form an angle, the emission of light focus and receive light focus cross-area detection object for fine detection, such as marking detection.
(7) coaxial detection (single lens)
In this way the transmitter and receiver are integrated, the emission of light through the coated translucent lens 45 ° refraction after the launch through the lens focus, the received light through the focus lens into the receiver, mainly for marking detection. At present the mainstream of the color sensor, logo sensors are mostly used in this way.
(8) Optical fiber type
Fiber optic fiber referred to as fiber, the current fiber optic photoelectric switch fiber is basically two, a plastic fiber, the price is relatively low, the general use of testing; another glass fiber, the price is relatively high, some high precision detection occasions.