Proximity Sensor
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The document discusses various types of proximity sensors including inductive, capacitive, photoelectric, magnetic, infrared, and ultrasonic sensors. It provides definitions and descriptions of how each sensor works, including common components, detection ranges, and applications. For example, it explains that inductive sensors detect metallic objects using magnetic fields while capacitive sensors detect non-metallic objects by measuring changes in capacitance. Common applications mentioned include parking sensors, engine sensors, and conveyor systems.
Proximity Sensor
- 2. Definition Types of Proximity Sensor Inductive Sensor Capacitive Sensor Photoelectric Sensor Magnetic Sensor Infrared Sensor (IR Sensor) Ultrasonic Sensor
- 3. A proximity sensor is a sensor able to detect the presence of nearby objects without any physical contact. Detects an object when the object approaches within the detection range or detects when an object enters the sensor’s field without any physical contact.
- 4. A proximity sensor often emits an electromagnetic field or a beam of electromagnetic radiation (infrared, for instance), and looks for changes in the field or return signal. Symbol
- 5. Inductive Sensor (Definition, Components, Range, Construction & Application) Capacitive Sensor (Definition, Components, Range, Construction & Application) Photoelectric Sensor (Definition, Components, Types, its definition & application) Magnetic Sensor (Definition, Types & Application) Infrared Sensor (Definition & Types & Application) Ultrasonic Sensor (Definition, Working Principle & Application)
- 6. An Inductive proximity sensor is an electronic proximity sensor , which detect metallic (Ferrous) object without touching them. The operating principle is based on a coil and high frequency oscillator that creates a field in the close surrounding of the sensing surface . Symbol
- 7. The Main components of the Inductive Proximity sensor are: ◦ Coil ◦ Oscillator ◦ Detector ◦ Output Circuit. The coil generates the high frequency magnetic field in front of the face. when the metallic target comes in this magnetic field it absorbs some of the energy. Hence the oscillator field is affected. The rise or fall of such oscillation is identified by a threshold circuit..that changes the output of the sensor.
- 8. The operating distance of the sensor depends on the coil’s size as well as the target’s shape, size and material. Sensing Range ◦ Only detects Ferrous materials ( Iron, Aluminum, Steel Copper) ◦ Approx 2mm to 40 mm.
- 10. i. Parking sensors, systems mounted on car bumpers that sense distance to nearby cars for parking. ii. Ground proximity warning system for aviation safety. iii. Vibration measurements of rotating shafts in machinery. iv. Camshaft sensor in reciprocating engines. v. Sheet break sensing in paper machine. vi. Roller coasters. vii. Conveyor systems. viii. Beverage and food can making lines. ix. Mobile devices (Touch screens).
- 11. An capacitive proximity sensor is an electronic proximity sensor , which detect non-metallic (Non-Ferrous) object without touching them. e.g. Liquids, Wood, Granulates, Plastic, Glass etc. In capacitive sensors, the two conduction plates (at different potentials) are housed in the sensing head and positioned to operate like an open capacitor. Air acts as an insulator; at rest there is little capacitance between the two plates. Symbol
- 12. The Main components of the Capacitive Proximity sensor are: i. Schmitt Trigger ii. Oscillator Circuit iii.Dielectric Materials iv. Output Circuit. As a target enters the sensing zone the capacitance of the two plates increases, causing oscillator amplitude change, in turn changing the Schmitt trigger state, and creating an output signal.
- 13. The internal plate is connected to an oscillator circuit that generates an electric field. The air gap between the internal plate and the external object serves as the insulator or dielectric material. When an object is present, that changes the capacitance value and registers as the presences of the object. Sensing Range ◦ Only detects Non-Ferrous materials (Liquids, Wood, Granulates, Plastic, Glass etc) ◦ Approx 3mm to 60 mm.
- 15. Flow: Many types of flow meters convert flow to pressure or displacement, using an orifice for volume flow. Capacitive sensors can then measure the displacement. Pressure: A diaphragm with stable deflection properties can measure pressure with a spacing- sensitive detector. Liquid Level Scanned multi-plate sensor Thickness measurement. Ice detector. Shaft angle or linear position in machinery circuitry. Limit switch.
- 16. A photoelectric sensor is a device used to determine the distance, absence, or presence of an object by using a light transmitter, often infrared, and a photoelectric receiver. The sensor is made up of a light source, an amplifier, signal converter, and an output. The output signal can be analog or digital and is often internally modified with timing logic, scaling, or other signal processing prior to output.
- 18. 1) Thru-Beam 2) Retro-reflective 3) Diffused
- 19. Thru-beam sensing, also known as opposed mode, two separate devices are used to make or break a beam. One sensor houses the light emitter while the other houses the receiver. A thru-beam sensor detects objects when an object interrupts the light beam between the two sensors.
- 20. The transmitter and receiver are separated. When the target is between the transmitter and receiver, the light is interrupted.
- 21. Detect very small objects. Detect the fill levels inside containers. Detect spliced or overlapped materials. Detect the contents of a container. Detect opaque objects. Detect the precise location of a specific object.
- 22. In retro-reflective sensing, both the light source and the receiving device are found in the same housing. The sensor works in tandem with a reflector. The light emitted from the sensor is aimed at the reflector, which is then sent back to the light receiving element. The sensor detects the presence of an object when the light path is interrupted.
- 23. Detect large objects. Detect objects moving at high speeds. Detect reflective tape at high speeds. Sense a transparent (clear) glass or plastic product.
- 24. In Diffuse, the light source and the receiver are housed in the same device. Diffused sensors detect objects when the light beam, emitted towards the target, is reflected back to the sensor by the target. What makes diffused sensors a great automation option is that they are more compact than typical units, as all components are in a single housing.
- 25. Detect multiple objects on a common conveyor system. Detect translucent objects. Detect the fill level inside containers. Detect the presence of parts, boxes, and web materials. Detect specific identifying features to determine an object’s orientation. Detect unwanted conditions for product inspection tasks.
- 26. Magnetic proximity sensors are non-contact proximity devices that are used to detect magnetic objects (e.g. permanent magnets). Magnetic sensor is a sensor which is used to notice disturbances as well as changes within a magnetic field such as strength, direction, and flux. Symbol
- 27. They sense the presence of a magnetic object, commonly referred to as the target. The target, characterized by its magnetic field, triggers the switching process when it enters the detection range of the sensor. The switch may be a reed switch or the device could operate due to inductive, variable reluctance, magneto resistive or hall effect operating principles. Used to measure the currents, speed, position and displacement.
- 28. 1) Low Field Sensors 2) Earth Field Sensors 3) Bias Magnet Field Sensors
- 29. It can sense very low values of magnetic fields, less then 1µG 1 Gauss = 10-4 Tesla ◦ e.g. SQUID, Fiber-Optic , Nuclear Procession Uses: In medical and nuclear application.
- 30. The magnetic range for the medium field sensors lends 1µGauss to 10 Gauss. Uses the Earth’s magnetic field in many of applications. e.g. ◦ Navigation ◦ Vehicle Detection
- 31. It can sense the large magnetic fields more then 10 Gauss. Most industrial sensors use permanent magnets as a source of the detected magnetic field. These permanent magnets magnetize, or bias, ferromagnetic objects close to the sensor. Sensors in this category include reed switches, Hall devices, and GMR sensors.
- 32. An infrared (IR) sensor is an electronic device that measures and detects infrared radiation in its surrounding environment. An IR sensor can measure the heat of an object as well as detects the motion. Symbol
- 33. 1) Active IR Sensor 2) Passive IR Sensor i. Thermal Infrared Sensor ii. Quantum Infrared Sensor Active IR Sensor ◦ Active infrared sensors both emit and detect IR radiation. ◦ Active IR sensors have two parts: a light emitting diode (LED) and a receiver. When an object comes close to the sensor, the infrared light from the LED reflects off of the object and is detected by the receiver. ◦ Examples: Break Beam Sensor, Reflectance Sensor.
- 34. Passive IR (PIR) Sensor ◦ Passive IR (PIR) sensors only detect infrared radiation and do not emit it from an LED. ◦ Examples: Thermocouple-Thermopile, Bolometer, Pyro-Electric Detector, etc.
- 35. Night Vision Devices Infrared Astronomy Human Body Detection Infrared Tracking (Infrared Homing) Art History and Restoration Gas detectors Water analysis Anesthesiology testing Petroleum exploration Rail safety Climatology
- 36. An ultrasonic sensor is an instrument that measures the distance to an object using ultrasonic sound waves. An ultrasonic sensor uses a transducer to send and receive ultrasonic pulses that relay back information about an object’s proximity. Symbol
- 37. An ultrasonic sensor can convert electrical energy into acoustic waves and vice versa. Ultrasonic waves travel faster than the speed of audible sound (i.e. the sound that humans can hear). Humans can detect sounds in a frequency range from about 20Hz to 20 KHz. The frequency range normally in ultrasonic detection is 100 KHz to 50MHz.
- 38. When an electrical pulse of high voltage is applied to the ultrasonic transducer it vibrates across a specific spectrum of frequencies and generates a burst of sound waves. Whenever any obstacle comes ahead of the ultrasonic sensor the sound waves will reflect back in the form of echo and generates an electric pulse. It calculates the time taken between sending sound waves and receiving echo. The echo patterns will be compared with the patterns of sound waves to determine detected signal’s condition.
- 40. Ultrasonic sensors can measure the following parameters, without even getting in contact with the medium which is to be measured : ◦ Distance ◦ Level ◦ Presence ◦ Diameter ◦ Position