Proximity sensors are gaining popularity in a variety of commercial and industrial applications. These devices are common for applications, from your mobile device’s mic and camera to an automatic cash register. But what about when you’re writing? What good do proximity sensors do for writers? Read further to learn how these devices can help wordsmiths.
With the constant evolution of technology, the world is growing smaller. Through technology and devices, we can connect with people all over the globe. So, it’s now possible to find a writing partner on the other side of the world without you even having to leave your home. This is where proximity sensors play their part in helping writers find writing partners for their work.
What is a proximity sensor?
A proximity sensor is a physical device often integrated into switches and doors. The sensor monitors the surrounding environment to detect when an object has encounter them. As a result, the proximity sensor triggers a response based on that detected object’s presence in its environment.
Proximity sensors come in a variety of formats and designs. But, they all work on the same basic principle of contact. These devices are small but very powerful in helping people connect.
How does a proximity sensor work?
Proximity sensors detect objects that encounter them. These devices use a metallic sheet or paper to detect those objects. In newer designs, capacitive proximity sensors pick up the metallic sheet or paper signal. We can use it for more accurate proximity detection.
To trigger proximity sensors, you’ll need to insert a piece of metal into the device’s field of view. When it detects that object in its field of view, it sends an electrical signal out over an electrical conductor. This signal directs the device to respond somehow, such as powering on a switch.
In some cases, the proximity sensor is self-powered. Others, such as those in your cell phone, need an external signal to power them. Once powered on, they pick up varying signal levels from the conductor. As a result, they can detect objects within different fields of view and send a signal based on the presence of that object in those areas.
Proximity sensors can have different responses equipped for each sensor. It depends on the application for which it’s intended. Proximity sensors will detect a wide variety of items. Some can detect metals, while others can only sense plastic, wood, or cloth. The type and amount of metal used in proximity sensors are dependent on the desired application.
Most proximity sensor devices will have a range of approximately 10-20 feet from their object. In some cases, RayMing PCB & Assembly is developing products to have longer detection distances. The distance approximates to 30-40 feet from their object.
Types of proximity sensors
We classify these sensors by their field of view, impacting how many objects they can detect in each area. There are six widely-used types of proximity sensors and some variations on those. These include:
1. Inductive Proximity Sensor
Inductive proximity sensors detect objects by their unique magnetic fields. These sensors can only detect metal objects. There are two types of inductive proximity sensors, which include:
a. Unshielded: These sensors can detect all metals. But they cannot distinguish between different metals. This means that it may not detect the desired objects.
b. Shielded: These sensors can distinguish between various types of metal. But they are still less accurate in detecting certain metals such as aluminum. These sensors may also pick up other objects from within that range and activate the proximity sensor.
Working Principle of Inductive Proximity Sensor
The operation of inductive proximity sensors depends on the principle of electromagnetic induction. The sensor uses a radio-frequency signal to transmit a magnetic field. They transmit it into the detection area. When an object interrupts this field, the sensor detects variations in the transmission frequency. It also generates an output signal to control the load.
These sensors are often used in energy control applications. They are reliable when you install them. These features make inductive proximity sensors the most used proximity sensor technology today.
2. Capacitive Sensor
A proximity sensor uses a capacitive sensing element instead of a metallic detection element. They are often helpful when you need a more accurate detection of specific metals like gold, silver, or copper. Capacitive sensors also have better resolution and detect more moldings than inductive sensors. This makes them the winner for some applications. It works best in medical settings where you need high accuracy and reliability in detection.
However, they are not that good at detecting non-metal objects such as glass and wood. It consists of an oscillator and a Schmitt trigger. Manufacturers couple it with a variable impedance and capacitance circuit. The oscillator generates an alternating electromagnetic field. When an object interrupts the field, this causes the oscillator’s signal changes. We detect this by a Schmitt trigger, which generates an output voltage to control the load.
Capacitive Proximity Sensor Working Principle
The capacitive perimeter sensor working principle is similar to that of inductive sensors. But it uses two coils (or resonant circuits) instead of one. One of the coils is a transmitter, which generates an electromagnetic field. The other is a receiver, whose function is to detect changes in the signal of the transmitter coil.
We install capacitive sensors differently from inductive ones. So, you can connect the transmitter coil directly to the supply voltage. We connect the receiver coil or coils to a capacitive sensing capacitor. The capacitor’s purpose is to store energy to maintain high-level voltage temporarily. It does this at its output terminals when no objects are present.
3. Photoelectric Sensor
Photoelectric sensors can detect objects that consist of non-metallic materials. This type of sensor is often used in the medical field to detect whether an object is a glass or metal. Other uses include detecting window breakage and even weld defects.
The operation of photoelectric sensors depends on a photo-emissive material. It produces or absorbs light when exposed to an electromagnetic field.
It has a laser diode, a photodiode receiver, and a light filter. The laser diode generates an electromagnetic field. It passes through the filter and the receiver. When an object interrupts the field, this causes the reflection of the electromagnetic energy in the receiver. The receiver detects this and triggers an output signal to control any load.
Electrical Properties of Photoelectric Sensors
Photoelectric sensors respond mainly to visible light (wavelengths between 400-700 nm). They are more sensitive to shorter wavelengths of light (400-500 nm) than to longer ones (700-800 nm).
The electrical characteristics of photoelectric sensors depend on the photo-emissive material used. It depends on how much light a sensor can detect and its wavelength. For example, glass or plastic can emit or absorb light at wavelengths between 350-450 nm. Many metals emit light in the range of 400-500 nm.
4. Ultrasonic Sensor
Ultrasonic sensors are virtually unaffected by non-metallic objects. These sensors are also less prone to interference from electrical and magnetic fields. It is suitable for use in noisy environments. They can recognize up to seven objects in the detection zone at a time. But they have a narrower field of view than inductive sensors.
Ultrasonic Sensors Working Principle
Ultrasonic sensors work by emitting ultrasonic pulses. It then measures the time taken for these signals to reflect off objects. To detect an object, we must interrupt the ultrasonic sensor’s pulses. When an object interrupts the pulses, it sends a signal to the control circuit that initiates output action.
We can find Ultrasonic sensors in industrial environments. They detect objects buried deep within a large volume of material.
Ultrasonic Sensors Applications
Ultrasonic sensors have the following applications:
Pulse Ultrasonic Sensor
A pulse ultrasonic sensor can transmit and receive a series of pulses through an object. This returns information about the object’s position. The time for this signal to return is then measured. We then indicate whether an object is present in a predetermined region. One can use this type of sensor for applications as diverse as identifying objects. You can also use it to determine if a material is ready.
Ultra-sonic sensors are available in different types, single-channel and multi-channel. Single-channel sensors transmit a single pulse. Then wait for the return echo before transmitting the next pulse.
Ultrasonic sensors are available in different sizes, from small disks to large strips. We may use them singly or grouped to form an array.
5. Retro-Reflective
Retro-reflective sensors are essential for safety and security purposes. When an object interrupts the laser beams, this causes a change in the beam’s polarization. The receiver detects it.
The light reflected off objects and surfaces does not affect them. So, they are ideal for use in applications with multiple reflection sources.
Retro-Reflective Sensor Working Principle
Retro-reflective sensors work by transmitting light from a laser source in a specific direction. When an object interrupts the light beam, there is change in the beam’s polarization. A receiver detects this interruption and triggers an output signal to control any load.
Retro-Reflective Sensor Applications
We use Retro-reflective sensors for industrial applications. They can detect objects buried deep in many materials, such as containers or pipelines.
Retro-Reflective Sensors also help in safety and security applications in the following areas:
6. Proximity Switch
The proximity switch is a common device that detects an object’s presence within a predetermined region. It generates an output signal when it detects that object. It consists of a transmitter coil and a receiver coil. The function of the transmitter is to generate an electromagnetic field. It then passes through a glass lens cover and receiver. The receiver can detect the interruption of this field. It then sends a signal to the control circuit that initiates output action.
The transmitter coil consists of an electric wire wrapped around a ferrite core and attached to a printed circuit board. The receiver operates by transmitting electromagnetic waves in a predetermined direction. It is then reflected through the glass cover back to the receiver. This causes a change in the signal’s voltage and frequency. The preamplifier then detects it. Then, we amplify this change with a low-noise amplifier, rectified, and directed to the control circuit.
Benefits of Proximity Sensors
Proximity sensors are helpful to detect the presence of an object within a predetermined region. We also use them for applications such as detecting if an object is approaching an edge. Proximity sensors can be beneficial in applications where an object needs protection from damage.
1. Contactless sensing
We can embed the sensor in an object, such as a vehicle. It is then driven into the vicinity of the object to detect any interference. We can measure the time taken for the system to respond with a timer. Also, we can use it to indicate whether an object is present in a predetermined region.
2. Unaffected by surface conditions
Proximity sensors do not need the object to contact the target directly. Surface conditions do not affect it. The sensor will still detect if an object’s surface is further from the transmitter coil than its height.
3. Suitability for a wide range of applications
Proximity sensors are helpful in a wide variety of applications. They include sensing the presence of an object or surface. Examples include detecting an approaching vehicle before it collides with a person or object. They can also trigger other devices when an object is present, such as starting a machine.
4. Longer service life
Proximity sensors can sustain the long-term operation. This is due to their self-diagnostics and automatic repair capabilities. They have a longer service life than most switch types. Compared to switches where we contact an object and then break, proximity sensors do not need the breaking of a switch.
5. Environmental sensibility
Proximity sensors are completely resistant to environmental conditions. We can use them in applications where parts of a machine. One can bury these objects deep within a volume of material, such as containers or pipelines. The sensor does not need protection from moisture or corrosion. A robust design ensures higher reliability and long life for industrial applications.
6. Low cost
Proximity sensors are not as expensive as other inertial sensing systems. This is due to their simplicity and ease of manufacture. Proximity sensors are also easier to install and cheaper to maintain.
7. Accurate detection
Proximity sensors can be more accurate than other objects because they cannot move around or change position. The sensor can detect very small changes in the distance caused by atmospheric conditions. They are not detectable by optical systems.
The common application for proximity sensors
A proximity sensor is helpful in industrial applications where an object or surface needs detection. We use them for applications such as detecting if an object is approaching an edge of a machine or if someone is standing too close to a machine. Proximity sensors can also trigger other devices when an object is present, such as starting a machine.
We can classify proximity Sensors into two major types:
Passive sensors
Passive proximity sensors require no power to operate. They detect the presence of an object by reflecting its electromagnetic field. The transmitter coil is stationary and attached to a printed circuit board. We then turn on the receiver with an output signal when an object passes into its range.
Active (Power-requiring) proximity sensors
Active proximity sensors need the power to operate. They use the power to transmit an electric field from the transmitter coil to the receiver through a glass lens cover. The receiver detects the interruption of this field. It then sends a signal to the control circuit that initiates output action.
Key applications include:
1. Use in Mobile phones
Proximity Sensors are helpful in mobile phones to detect if the phone is on the user’s hand or falls from a height. Mobile phones may also use a proximity sensor to determine if the phone is lying on a surface, such as the back of a car seat. The Android operating system uses proximity sensors, such as the Browser and YouTube. iOS uses proximity sensors to turn on/off the display of iPhones. The Google Play store also includes applications that use proximity sensors. For example, alarm clocks, LEGO Mindstorms, and interactive toys for children. Use in Robots
2. Use in parking
Automobile parking assist systems are also known as park-assist or parking sensors. When reversing, they use an infrared beam to detect objects within the car’s path. We usually install the sensor within the bumper of a vehicle. When the driver intends to reverse, the car transmits an infrared beam to a receiver unit attached to the rear bumper. It will detect any object that interrupts this beam. A warning light will illuminate for the driver to stop. We often use the proximity sensor with the vehicle’s transmission and engine control unit.
3. Use in conveyor applications
A proximity sensor is a small device used along with a conveyor to ensure the transported product doesn’t fall or get lost. The sensor works like a switch. It closes the circuit when we place something on it and opens it when no object is present. We use this type of sensor in food processing, recycling, and waste sorting industries. We also use them in many other applications to monitor human or machine presence.
4. Use in medical
Proximity sensing is helpful in various medical applications. We use prescription drugs, refill bottle labels, adjunct to glucometers, and insulin pens. We also use the sensors for locating breathing and heart rates. Proximity sensing can also be helpful for safety purposes. They include preventing hand-to-electrode contact during EKG application. We use proximity sensors in hospitals to detect the removal of equipment or supplies from a general storage area.
5. Use in automatic faucet
An automatic faucet uses a proximity sensor to monitor the water flow rate of a stream of water. The sensor receives an electrical signal from the faucet that shows the stream’s amount of water currently in use. The sensor usually connects to a water service valve. It will close the circuit when we need more water. It stops the flow and resets back to normal once it receives no longer than three pulses within 10 seconds to allow water flow again.
6. Use in Security
Electronic locks, such as the PIN pad, on the control panel, will not open until a person activates the keypad with a PIN code. If no one enters a code within three seconds, the circuit will open. We achieve this by using passive proximity sensors in each keypad with an electronic lock.
7. Use in fire detection
Door and window sensors help detect if a door or window is open. These sensors are commonly helpful in places of business, for instance, stores and offices. They can protect against burglary and fire damage to property. These sensors have a transmitter and receiver. We attach a transmitter to the door or window frame and connect the receiver to a control panel. The receiver will not allow the circuit to open unless it receives a signal from the transmitter. This prevents a thief from breaking into the building through a window or door and prevents damage to property by fire.
8. Use in collision detection systems
Proximity sensors can help collision detection systems. They can detect when a vehicle is moving at high speed or suddenly coming to a stop. Proximity sensors are also helpful in industrial applications such as machine control.
How to turn off proximity sensor
Proximity sensors are present in smartphones, tablets, and laptops. A small sensor is usually present at the bottom of the device between the display and the home button. The proximity sensor detects when you hold your phone to your ear and turn off the screen. Sometimes proximity sensor does not respond properly. It does not turn off the screen on time after taking your phone away from your ear. In this case, you can manually turn off the proximity sensor on Android or iPhone.
iPhone Proximity Sensor
Go to your iPhone settings, go to general and then head over to accessibility. Under the accessibility option, select magnifier gestures to turn off the proximity sensor. Alternatively, you can turn off the proximity sensor on an iPhone manually. First, press the Settings button and then touch “General.” Choose the Accessibility option and tap on “Display Accommodations” on your screen. Now tap on “Auto-Brightness.” To turn off the proximity sensor, tap on “Auto-Brightness” in the “Display Accommodations” section. A new panel will appear to choose to show or hide the proximity sensor. Choose “On” to turn off the proximity sensor. Next time you put your phone near your ear or rest it on your ear, the screen will turn off automatically by default.
Android Proximity Sensor
Go to Settings > Display > Auto-Brightness > Auto-Brightness. To turn off the proximity sensor, you need to turn “Mirroring.” Next, select the circle on the left-hand side labeled as Screen Calibration. This will allow you to choose your brightness level. Choose a level where the display is not too bright or dark for a comfortable view. To turn off the proximity sensor, tap on it and select on-off. Now your screen will turn off automatically when you place your phone on your ear or rest it near you.
Proximity Sensor Android that turns off the screen is present in most smartphones. But if it does not appear in your phone, you can turn it off by installing the Xposed module and enabling the proximity sensor of the module.
Conclusion
The proximity sensor is a kind of switch that senses an object’s presence or absence in its proximity. These sensors are widely helpful in many industries. They detect the presence of objects and secure them from falling, theft, and unauthorized use.
We can find different proximity sensors in many electronic devices like phones, laptops, and tablets. The most common use of proximity sensors is to turn off the screen when you hold your phone to your ear.
