I. Photoelectric Switch
1. Working principle
A photoelectric switch is a sensor that detects the presence or passage of an object by detecting changes in a light beam. It typically consists of three parts: a transmitter, a receiver, and a detection circuit. The transmitter aims a light beam at the target; this beam can originate from a light-emitting diode (LED) or a laser diode. When an object passes through the beam, the beam is reflected or blocked. The receiver detects this change and generates a corresponding switching signal.
2. Type
There are several types of photoelectric switches, including diffuse reflection, specular reflection, through-beam, slotted, and fiber optic. Diffuse reflection photoelectric switches reflect enough light to the receiver to generate a signal when an object passes by. Specular reflection switches rely on an object completely blocking the light to generate a signal. Through-beam photoelectric switches consist of a separate transmitter and receiver, which block the light when an object passes between them. Slotted photoelectric switches are suitable for detecting high-speed changes, while fiber optic photoelectric switches can detect objects when they are not in close proximity.
3. Features
(1) Longer testing distance. Compared with inductive proximity switches, photoelectric switches can achieve a longer testing distance.
(2) Unaffected by magnetic fields and vibrations. Test switches are often installed in places with strong magnetic fields and vibrations, but photoelectric switches are rarely affected by them and can be used reliably.
(3) High resolution. Light travels in a straight line and has a short wavelength, resulting in high resolution, making it suitable for testing small objects and high-precision positions.
(4) Wide range of test objects. Almost all materials, including metals, glass, rubber, wood, liquids, and gases, can be tested.
(5) Easy to obtain a regular test area. The photoelectric switch adopts optical systems such as lenses, which can easily focus, diffuse and refract light. Depending on different test objects and usage environments, products with a certain test area can be appropriately selected.
(6) Fast response speed. Photoelectric switches contain almost no mechanical movement, thus enabling very high testing speeds.
(7) It can utilize the properties of light for testing, and can perform tests such as color mark and shape feature selection.
The MGK series photoelectric switches are a product of modern microelectronics technology and an upgraded replacement for the HGK series infrared photoelectric switches. They possess significant advantages over previous photoelectric switches:
● It has a self-diagnostic stable operating area indicator function, which can promptly inform you whether the working status is reliable;
●Through-beam, reflective, and specular reflective photoelectric switches all have anti-interference functions and are easy to install;
●Configuring the ES external synchronization (external diagnostic) control terminal allows for pre-checking of the photoelectric switch's proper functioning before operation. It can also accept interrupt or detection commands from a computer or programmable controller at any time. Appropriate combinations of external and self-diagnostic capabilities can make the photoelectric switch intelligent.
●Fast response speed: The high-speed photoelectric switch can achieve a response speed of 0.1ms and perform 300,000 detection operations per minute, enabling it to detect tiny objects moving at high speeds;
● Employing application-specific integrated circuits and advanced surface mount technology (SMT), it boasts high reliability;
● It is small in size (only 20×31×12mm), lightweight, easy to install and debug, and has short circuit protection function.
II. Photoelectric Relay
1. Working principle
An optoelectronic relay is a type of solid-state relay that uses optical coupling technology to achieve electrical isolation between the input and output. It mainly consists of a light-emitting diode (LED) and a photosensitive element (such as a phototransistor or MOSFET). When the LED at the input terminal emits light, the photosensitive element converts the light intensity into a corresponding electrical signal, thereby controlling the conduction or cutoff of the output terminal.
2. Features
Compared to traditional mechanical relays, photoelectric relays offer advantages such as longer lifespan, lower current operation, and faster response. Because they have no physical contacts, photoelectric relays reduce wear and noise, improving reliability. Furthermore, photoelectric relays can provide high insulation resistance between input and output, typically a minimum of 1000 MΩ.
III. Application Scenarios
1. Photoelectric switch
Photoelectric switches are widely used in level detection, liquid level control, product counting, width discrimination, speed detection, fixed-length shearing, hole identification, signal delay, automatic door sensing, color mark detection, punching and shearing machines, and safety protection. They are also commonly used in smoke detectors in security systems and in counting the number of movements of robotic arms in industry.
2. Photoelectric relay
Optical relays are commonly used in applications requiring electrical isolation, such as signal switching, circuit control, and power management. Due to their high insulation properties, optical relays are suitable for high-voltage or high-current applications, such as power control systems and industrial automation equipment.
