A text to understand the application of the sensor
Proximity sensors have long service life, reliable operation, high repeatability, no mechanical wear, no spark, no noise, strong anti-vibration ability. It can be used as a limit, counting, positioning control and automatic protection in the automatic control system. It is widely used in machine tools, metallurgy, chemical, textile and printing industries.
Before we talk about the proximity sensor application, let's take a look at some of the main features it has:
1, inspection distance
Detecting the stop, start and pass position of the elevator and lifting equipment; detecting the position of the vehicle to prevent collision of two objects; detecting the set position of the working machine, moving the limit position of the machine or component; detecting the stop position of the rotary body, the valve Open or close position; detect the position of the piston in the cylinder or hydraulic cylinder.
2, size control
The size control device for metal plate punching; automatically selects and identifies the length of the metal piece; detects the height of the pile during automatic loading and unloading; and detects the length, width, height and volume of the article.
3. Is there any presence of the detected object?
Detect whether there is a product packaging box on the production packaging line; check for product parts.
4, speed and speed control
Control the speed of the conveyor; control the speed of the rotating machine; control the speed and number of revolutions with various pulse generators.
5, counting and control
Detect the number of products flowing through the production line; the number of revolutions of the rotating shaft or disk at high speed; the count of parts.
6, detection abnormalities
Check the presence or absence of the bottle cap; judge the product's pass and fail; test the lack of metal products in the package; distinguish metal and non-metal parts; product with or without signage detection; crane danger zone alarm; safety escalator automatically start and stop.
7, measurement control
Automatic metering of products or parts; detecting the range of pointers of gauges and meters and controlling the number or flow; detecting buoys to control the height of the measuring surface, flow rate; detecting iron buoys in stainless steel barrels; controlling the upper or lower limit of meter range; flow control, horizontal control.
8, identifying objects
Identify the right and wrong according to the code on the carrier.
9, information transmission
The ASI (bus) connects the sensors at various locations on the device to and from the data line in the production line (50-100 meters).
At present, proximity sensors are widely used in aerospace, industrial production, transportation, consumer electronics and other fields. Here are some typical application scenarios to open up for your proximity sensor application design. Some ideas.
Application of human proximity sensor in ATM cash machine monitoring
The human proximity sensor is a control device for detecting the proximity of the human body. It can accurately detect the proximity of nearby people and is currently the best choice for alarm and state detection. Its sensing part has high detection sensitivity for nearby people's movement, and it suppresses the sound signal of the surrounding environment, and has strong anti-interference ability. The internal use of micro-circuit chip for program control processing, with high detection sensitivity and trigger reliability, detection and control two parts into one, low standby power consumption, switching signal output, directly trigger alarm recording.
Since the sensitivity to human body sensing is continuously adjustable, this allows the human proximity sensor to be used in many different applications. In terms of security and theft, such as data files, accounting, finance, museums, treasury, etc., it is usually equipped with anti-theft devices composed of various proximity sensors.
Application of proximity sensor in aircraft landing gear system
Aerodynamics, landing gear systems, and navigation systems are among the top three systems reported by airlines for reporting difficulties in aircraft use. Among them, the failure of the landing gear system is likely to cause abnormal events such as aircraft returning and standby, which will bring economic losses to the company and bring hidden dangers to aviation safety.
In a typical Airbus landing gear control system, a digital telex control system is typically employed. The basic principle is to send the sensor signal to the control box (control computer), and after the comprehensive operation comparison, the instruction is sent to the actuator, and the control link is the margin control.
Modern civil aircraft landing gear retracting includes two systems of normal retraction and emergency release. The landing gear control system uses fly-by-wire manipulation in the handling mode and cross-links with other systems. Inductive proximity sensors are widely used to detect the position of the landing gear.
There are two main sensors for each landing gear, namely the lock sensor and the drop lock sensor, which are used to close the transmission position signal when the lock is closed and put down. This type of sensor is a reluctance type proximity sensor and is mainly composed of two parts: a sensor body and a sensor excitation piece.
The sensor body converts electrical energy into a magnetic field, and the excitation sheet mainly serves to increase the magnetic permeability. The permeability increases as the landing gear and the actuator approach a certain distance, and the sensor signals the warning component to indicate the landing gear position. The distance between them directly affects the accuracy of the indication, and the general adjustment requirements are also strict. In addition, different models are slightly different, you need to refer to the AMM manual of this model when adjusting.
Inductive proximity sensors detect the position of the landing gear and increase sensor life. In addition, information transmission and information sharing with the avionics system are conveniently realized by the control computer.
Application of proximity sensor in monitoring of iron track mouth
In all railway accidents, train collisions account for a large part and often have serious consequences. The use of proximity sensors to monitor passing trains at intersections has become a very important part of improving railway safety measures.
In practical applications, the proximity sensor non-contact position measurement features can be used to symmetrically mount the two ends of the intersection rail. When a train passes, the proximity sensors at both ends of the rail can detect changes caused by the passage of the respective end wheels. Through the crossing monitoring micro-processing system to analyze each sensor signal, it can determine the direction in which the vehicle travels and the state when it passes (pass or not, whether it stays or not). Finally, the information is sent to the traffic control center by cable or wireless communication to transfer the train.
Application of proximity sensor in automatic packaging machinery
Mechanized manufacturing has created a demand for automatic packaging technology, and the method of manual packaging is far from satisfactory for mass production operations. The automatic packaging machine can complete the packaging process of a series of articles under the guidance of the control system, improve the packaging efficiency of the product, and reduce the packaging cost, but it will inevitably lead to leakage. To this end, automatic packaging testing has become an important part of ensuring the quality of packaging. Among them, in the case of a ferromagnetic substance in the packaging process, non-contact detection using a proximity sensor is a commonly used method.
A coil that is close to the inside of the sensor that generates an alternating magnetic field, when the detected ferromagnetic material is in the environment, forms an eddy current internally due to the electromagnetic induction principle. When the magnetic field generated by the eddy current is large enough, the original circuit parameters of the proximity sensor are reversed to generate a signal output. Therefore, the proximity sensor can be used to identify whether a magnetic or easily magnetized substance exists in a certain range in the vicinity. In some automatic packaging processes, such as chocolate foil packaging, the proximity sensor can detect the presence of magnetic substances, and it can be judged whether there are packaging errors or defective products that are missing in the process, thereby improving the packaging quality.
Application of proximity sensor in robot hand gripper
The robotic hand gripper is a mechanical structural component that has multiple degrees of freedom and is capable of gripping objects with dexterity. It can be used in various industrial automation production, assembly and operation, and can perform tasks such as information detection, item collection and detection, and detonation in a high-risk environment. Robot hand grippers generally use a pincer structure to pick up objects in an open and closed manner. Therefore, the accurate measurement and control of the "nip" opening degree is a key factor that directly affects the success of the gripping process.
Since the proximity sensor can sense the change of the distance and the position, it is also a common sensor device for measuring the opening and closing of the robot hand gripper, which uses the relative positional relationship between the change of the magnetic field and the metal component to be measured. Usually the sensor is mounted on one of the clamps of the holder. When the object is gripped, the proximity sensor can determine the distance between the two (clamp) by sensing the magnitude of the magnetic field. Therefore, it can be compared with the set value to adjust the opening degree of the hand gripper to avoid catching or damaging the object.
Application of capacitive proximity sensor in automotive electronics
The demand for proximity sensors in automotive electronics applications has steadily increased, and the potential applications for proximity detection in the automotive electronics industry are limitless, such as:
Car access control: the detection hand is close to the door handle, and then the unlocking process is started.
Illuminates and wakes up the touch screen when the palm is close to the surface of the screen
Turns the interior lights on/off when the palm is close to the sensor
Turn the device on/off by detecting the simple action of the palm in the air
Detecting large obstacles around the car during parking
For a variety of automotive electronics applications, there are a variety of proximity detection methods, such as capacitive sensing, infrared, ultrasonic, optical and so on. For proximity detection from 5mm to 300mm, capacitive sensing technology has many advantages over other technologies: excellent reliability, simple mechanical design, low power consumption and low cost.
An example of capacitive proximity detection is in automotive access systems (see figure below). A proximity sensor that detects the proximity of a human hand is located in the door handle (1). Upon detecting the proximity of an object, the main control unit (2) sends a wake-up signal via the low frequency antenna (3); this signal activates the car key transmitter (4). The car key transmitter then exchanges information with the RFID receiver (5); if the coded information matches the main control unit (2), the car door lock is opened. The entire process of proximity detection and ID identification is about a fraction of a second. This means that when the door handle is pulled, the door lock is already open.
Compared to touch detection, the advantage of using proximity detection in a car access system is that it can preempt the time of identifying the owner, with the result that the door lock is already open before the door is pulled.
Detecting space gestures for turning devices on or off is also a common application in automotive electronics. Using two or more capacitive proximity sensors simultaneously, you can turn the device on or off by detecting simple movements of the palm in the air, such as waving in front of the device being inspected. The following figure shows a simple example of using such a system to turn on/off the interior lighting of a car. Turning the light in one direction against the light is turning the light on, and waving in the opposite direction turns off the light. The system is capable of analyzing the signal of the proximity sensor, determining whether the gesture indicates to turn the light on or off.
There are many different ways to design a sensing electrode in an electric lamp, from the use of thin copper wire to the use of conductive polymers that can be directly attached to plastic.
Application of proximity switch sensor on screen door
For safety, subway screen doors are increasingly being used by subway stations. Proximity switch sensors will be heavily invested in the technical application of screen doors, and subway accidents will be minimized in sensor applications.
At present, the screen door system is used to detect the common scheme of opening and closing the door, and generally the door is opened and closed by two proximity switches. Since the proximity sensor can be detected in a non-contact manner, it does not wear and damage the object to be detected. This is also one of the main reasons why it is suitable for installation on the subway. As the performance of the proximity sensor is further improved, it will be applied to more occasions. In the future, it will not only be a subway gate, but also have a wide range of applications on other screen doors such as buses.
Application of proximity sensor in touch screen mobile phone
Proximity sensors use MEMS technology and are popular in smartphones.
At the beginning of the popularity of touch-screen phones, users found a flaw in the touch screen: when we pick up the phone in the most common position, the face will often touch the touch screen, inadvertently clicked on the hook button or hands-free button, resulting in Unnecessary embarrassment. Therefore, mobile phone manufacturers use MEMS technology to design MEMS proximity sensors into touch-screen mobile phones, and automatically lock screens when answering calls to avoid false triggering. In addition, the lock screen can also turn off the backlight, which can effectively save energy and extend standby time.
The smart phone uses a MEMS ambient light sensor and a proximity sensor: ambient light detection (determination of ambient light and darkness based on the amount of light detected by the light receiving portion of the sensor) and proximity detection (light from the light source with the sensor) On the measurement object, the distance from the distance measuring object is determined based on the amount of light that is reflected to the proximity of the sensor.
The ambient light sensor optimizes the illumination of the LED backlight so that our mobile phone can adjust itself to the right brightness in any environment, whether it's in a dimly lit movie theater or in a well-lit outdoor environment. The proximity sensor can turn off the touch screen when answering the call, so that we won't touch the buttons on the screen and suddenly hang up or click on other functions.
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