Eight classic applications of proximity sensors, how many do you know

Keywords: photoelectric switch photoelectric switch manufacturer photoelectric switch model photoelectric switch price photoelectric switch wiring diagram photoelectric switch principle photoelectric switch type photoelectric switch application

Photoelectric switch:

The photoelectric switch is the abbreviation of the photoelectric proximity switch. It utilizes the shielding or reflection of the light beam by the detected object, and the circuit is connected by the synchronization loop to detect the presence or absence of the object. Objects are not limited to metal, all objects that can reflect light (or block light) can be detected. The photoelectric switch converts the input current into a light signal on the transmitter, and then the receiver detects the target object according to the intensity or presence of the received light. The common photoelectric switch smoke alarm in the security system is often used in the industry to count the number of movements of the robotic arm.

Photoelectric switch model:

The photoelectric switch is a kind of sensor, which converts the change of the intensity of light between the transmitting end and the receiving end into the change of current to achieve the purpose of detection. Since the output circuit and input circuit of the photoelectric switch are electrically isolated (ie, electrically insulated), it can be used in many occasions. A new generation of photoelectric switch devices manufactured using integrated circuit technology and SMT surface mounting technology has intelligent functions such as delay, widening, external synchronization, anti-interference, high reliability, stable working area and self-diagnosis. This novel photoelectric switch is an active photoelectric detection system electronic switch that adopts pulse modulation. The cold light sources it uses include infrared light, red light, green light and blue light, etc., which can be non-contact and rapid without damage. And control the state and action of various solids, liquids, transparent bodies, black bodies, soft bodies and smoke. It has the advantages of small size, multiple functions, long life, high accuracy, fast response speed, long detection distance and strong resistance to optical, electrical, and magnetic interference.

Photoelectric switch manufacturers:

Use optical elements to change the light beam in the middle of the propagation medium; use the light beam to reflect the object; make the light beam return instantly after a long distance. The photoelectric switch is composed of three parts: transmitter, receiver and detection circuit. The transmitter is aimed at the target to emit a beam, and the emitted beam generally comes 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 beam has been selected many times in the launch, and it runs towards the target without indirectly. The receiver is composed of a photodiode or phototransistor. In front of the receiver, optical components such as lens and aperture are installed. Behind it is the detection circuit, which can filter out the effective signal and apply the signal.

Working principle of photoelectric switch:

After the modulated pulse generated by the oscillation circuit passes through the reflection circuit, the light pulse is radiated from the light emitting tube GL. When the measured object enters the range of the light receiver, the reflected light pulse enters the photosensitive transistor DU. The photoelectric switch demodulates the optical pulse into an electric pulse signal in the receiving circuit, and then is amplified by the amplifier and synchronized gating and shaping, and then the interference is eliminated by digital integration or RC integration, and finally the driver is triggered by a delay (or no delay) Output photoelectric switch control signal. Photoelectric switches generally have good hysteresis characteristics, so even if the detected object shakes in a small range, it will not affect the output state of the driver, so that it can be kept in a stable working area. At the same time, the self-diagnostic system can also display the light receiving status and stable working area to monitor the work of the photoelectric switch at any time.

Types of photoelectric switches:

The amplifier separation type is to separate the amplifier and the sensor, and is made with a dedicated integrated circuit and a mixed installation process. Because the sensor has the characteristics of ultra-small and multi-variety, the amplifier has more functions. Therefore, this type adopts the terminal block connection method and can be used for both AC and DC power supplies. With on and off delay function, you can set the light and sound switch, can control 6 kinds of output states, and have two output modes of contact and level.

The built-in type of amplifier integrates the amplifier and the sensor. It is made by ASIC and surface mounting technology, and it works with DC power supply. Its response speed situation (there are two kinds of 0.1ms and 1ms), can detect small and high-speed moving objects. Changing the polarity of the power supply can switch between bright and dark movement, and can set a self-diagnostic stable work area indicator. Both voltage and current output modes can prevent mutual interference, which is very convenient in system installation.

The built-in power supply unit integrates the amplifier, sensor and power supply device, and is made with a dedicated integrated circuit and surface mount technology. It generally uses AC power and is suitable for replacing contact type limit switches at the production site, and can be directly used for strong current control circuits. You can also set self-diagnostic stable working area indicator lights by yourself. The output is equipped with SSR solid state relay or relay normally open and normally closed contacts, which can prevent mutual interference and can be installed tightly in the system.

Photoelectric switch price:

Strong light source: The photoelectric switch can generally work stably when the ambient illuminance is high. However, it should be avoided that the optical axis of the sensor faces strong light sources such as sunlight and incandescent lamps. When the angle between the optical axis of the sensor (receiver) and the strong light source cannot be changed, a light-shielding plate or a long light-shielding tube can be installed around the sensor.

Mutual interference: MGK series of new photoelectric switches usually have the function of automatically preventing mutual interference, so there is no need to worry about mutual interference. However, when several groups of HGK series through-beam infrared photoelectric switches are installed in parallel and close to each other, the adjacent groups and mutual interference should be prevented. The most effective way to prevent this kind of interference is to set the emitter and the receiver crosswise, and open the group distance when more than 2 groups. Different frequency models can also be used.

The effective way of HGK series reflective photoelectric switch to prevent mutual interference is to open the interval. And the farther the detection distance is, the larger the interval should be, and the specific interval should be determined according to the debugging situation. Of course, models with different operating frequencies can also be used.

Photoelectric switch wiring diagram:

The slot photoelectric switch is usually a standard U-shaped structure. The transmitter and receiver are located on both sides of the U-shaped groove and form an optical axis. When the detected object passes through the U-shaped groove and blocks the optical axis, the photoelectric switch The detected switch signal is generated. The slot photoelectric switch is safer and more suitable for detecting high-speed changes and distinguishing transparent and semi-transparent objects.

Optical fiber photoelectric switches use plastic or glass optical fiber sensors to guide light, so as to realize the detection of objects not in the vicinity. Generally, fiber optic sensors are divided into through-beam type and diffuse reflection type.

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At present, proximity sensors are widely used in various industries such as aerospace, industrial production, transportation, consumer electronics, etc. Here are some typical application scenarios, so that you can open them in the application design of proximity sensors. Some ideas. Application of proximity sensor in touch screen mobile phone

Proximity sensors use MEMS technology and have been popularized in smart phones.

At the beginning of the popularity of touch screen phones, users discovered a flaw in the touch screen: when we pick up the phone in the most common gesture, our face often touches the touch screen and accidentally clicks on the on-hook button or the hands-free button, causing Unnecessarily embarrassing. Therefore, mobile phone manufacturers use MEMS technology to design MEMS proximity sensors into touch screen mobile phones, which automatically lock the screen when receiving a call to avoid false triggers. In addition, the backlight can be turned off while the screen is locked, which can effectively save energy and extend the standby time.

Smartphones use MEMS ambient light sensors and proximity sensors: that is, ambient light detection (using the amount of light detected by the light-receiving part to determine the surrounding brightness based on the illuminance of the sensor) and proximity detection (lighting from a light-emitting source equipped with a sensor) On the measurement object, the distance to the measurement object is judged based on the amount of light reflected on the proximity light-receiving part of the sensor). The ambient light sensor can optimize the lighting of the LED backlight, so that our mobile phone can self-adjust to the appropriate brightness in any environment, whether it is in a dim movie theater or a well-lit outdoor. The proximity sensor can turn off the touch screen when answering a call, so that we will not touch the buttons on the screen to suddenly hang up the phone or click on other functions.

Application of Capacitive Proximity Sensor in Automotive Electronics

The demand for proximity detection sensors in the automotive electronics application field has been steadily rising. The possible applications of proximity detection in the automotive electronics industry are limitless, such as:

Car access control: detect the hand close to the door handle, and then start the unlocking procedure. When the palm is close to the surface of the screen, it can illuminate and wake up the touch screen. When the palm is close to the sensor, you can turn on/off the interior lights. Simple detection of the palm in the air Action to turn on/off the device to detect large obstacles around the car during parking

There are a variety of proximity detection methods for various automotive electronic application requirements, such as capacitive sensing, infrared, ultrasonic, optical, etc. For proximity detection ranging from 5mm to 300mm, capacitive sensing technology has many advantages over other technologies: excellent reliability, simple mechanical design, low power consumption and low cost.

Application of Proximity Switch Sensor on Screen Door

For safety, subway screen doors are increasingly used by subway platforms. Proximity switch sensors will be heavily invested in the technical application of screen doors, and subway accidents will be minimized in the application of sensors.

At present, the common scheme used by the screen door system to detect the opening and closing of the door is to detect the opening and closing of the door through two proximity switches. Since the proximity sensor can detect in a non-contact manner, it will not wear and damage the detection object. 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 be widely used not only on subway doors, but also on other screen doors such as buses.

Application of Human Proximity Sensor in the Monitoring of ATM Cash Machine

The human proximity sensor is a control device used to detect the proximity of the human body. It can accurately detect the proximity of nearby people and is currently the best choice for alarm and status detection. Its sensing part has a high detection sensitivity to nearby people's movement, and it suppresses the sound signal of the surrounding environment, and has a strong anti-interference ability. The internal microcircuit chip is used for program control processing, which has high detection sensitivity and trigger reliability. The detection and control parts are combined into one, the waiting power consumption is low, and the switch signal output directly triggers the alarm recording.

Since the sensitivity of human body induction is continuously adjustable, this makes the human body proximity sensor suitable for many different occasions. In terms of security and anti-theft, such important places as data files, accounting, finance, museums, and vaults are usually equipped with anti-theft devices composed of various proximity sensors.