HackMDThere are five main types of proximity sensors, each based on different physical principles and suitable for various applications. Here's a breakdown:
1. Inductive Proximity Sensor
- Detects: Metal objects only
- How it works: Uses an electromagnetic field to detect eddy currents induced in metal targets
- Range: Short (typically < 10 mm)
- Advantages: Fast, reliable, resistant to dirt and moisture
- Common use: Industrial automation, CNC machines
2. Capacitive Proximity Sensor
- Detects: Both metal and non-metal (plastics, liquids, wood, etc.)
- How it works: Senses changes in capacitance when a target enters the electric field
- Range: Short to medium (a few mm to ~25 mm)
- Advantages: Versatile material detection
- Common use: Level sensing (e.g., for liquids or powders), presence detection
3. Optical (Photoelectric) Proximity Sensor
Detects: Any object that reflects or interrupts a light beam
How it works: Uses an IR LED and photodetector; detects object by reflection or beam interruption
Types:
- Reflective (diffuse)
- Retroreflective
- Through-beam
Range: Medium to long (up to several meters)
Common use: Object counting, packaging lines, automation
4. Ultrasonic Proximity Sensor
- Detects: Most objects (solid or liquid)
- How it works: Emits ultrasonic waves and measures the time of flight of the reflected signal
- Range: Medium to long (up to several meters)
- Advantages: Works in low visibility, detects transparent and reflective objects
- Common use: Distance measurement, obstacle detection in robotics, parking sensors
5. Magnetic Proximity Sensor (Reed or Hall Effect)
Detects: Magnetic fields (typically from a magnet)
How it works:
- Reed switch: Opens/closes in response to a nearby magnet
- Hall effect sensor: Measures magnetic field strength
Range: Short (a few mm to cm)
Common use: Door position detection, speed sensing, robotics
📘 Summary Table
