What Are Area Sensors: Detailed Look at Types, Materials, and Key Capabilities
Area sensors are multi-beam photoelectric sensors designed to monitor and detect objects within a defined area by creating a light screen composed of multiple beams. They are widely used in industrial automation and safety applications where the detection of objects' presence, movement, or position across a broad area is necessary, beyond what single-point sensors can achieve. This article provides a detailed look at the types, materials, and key capabilities of area sensors.
What Are Area Sensors?
Area sensors, also called array sensors or light screens, consist of a series of photocells or emitters and receivers arranged to cover an entire area with multiple beams of light. These sensors detect objects that interrupt these beams, allowing for precise detection across the full monitored zone without dead spots. They are typically installed orthogonally to the movement direction of objects, making them ideal for counting, measuring, and safety applications.
Types of Area Sensors
Area sensors come mainly in two configurations:
- Through-Beam Area Sensors: These sensors have separate emitter and receiver units aligned facing each other. Infrared light beams are emitted and detected across the sensing area, ideal for large coverage distances. They achieve high accuracy and resolution even with wide openings.
- Retroreflective Area Sensors: These use a single sensor unit with the emitted light reflected back from a reflector. They are simpler to install and cost-effective but mostly suited for small to medium range sensing applications. They often employ visible red light to ease alignment.
Within these categories, special models are available for demanding environments with features like air cooling for hot machine installation, IP69K rating for washdown environments, and ATEX certifications for explosive atmospheres. Beam pitch, which is the distance between light beams, can range from 10 mm for detecting objects as small as 5 mm to 6 mm pitch for detecting down to 2 mm objects.
Materials Used in Area Sensors
Area sensors are made from materials that ensure durability, precision, and sensitivity to light. Common materials include:
- Semiconductors: Silicon or polysilicon are commonly used as sensing materials for photodiodes and phototransistors within the sensors.
- Ceramics: Employed in sensors requiring piezoelectric or other advanced properties.
- Glass: Used in lenses and protective covers for optical components.
- Metals: For sensor housing to provide mechanical protection.
- Polymers: Materials such as SU-8 or PDMS are used for simpler and cost-effective manufacturing processes.
Emerging materials like graphene, nanowires, and advanced polymers are under research to enhance sensor performance, including sensitivity and robustness.
Key Capabilities of Area Sensors
- Wide Area Coverage: By emitting multiple beams, area sensors monitor large zones, unlike point sensors that scan only a single line or spot.
- High Detection Precision: With fine beam pitches and multiple detection modes (parallel and crossed-beam), these sensors detect objects, even very thin or small parts.
- Versatile Output Options: They can provide digital, analog, and communication interface outputs (such as Ethernet) for easy integration with PLCs and automation systems.
- Environmental Robustness: Many models are built to withstand harsh industrial environments with high IP ratings, temperature resistance, and suitability for hazardous areas.
- Non-Contact Sensing: Suitable for detecting objects without physical contact, eliminating wear and tear issues.
- Privacy and Security Features: Advanced computer vision-based area sensors offer data privacy by processing visual data locally and only transmitting positional coordinates rather than images.
- Adaptability and Integration: Their compact designs and varied beam arrangements allow easy installation in different settings, from conveyor belts to robotic cells.
Applications
Area sensors are widely used in industrial automation for detecting and measuring packages, parts, or pallets on conveyors, ensuring safety by creating protective light curtains, and performing position monitoring in logistics and end-of-line applications. Their high accuracy and reliability make them essential components in modern manufacturing and logistics processes.
Conclusion
In conclusion, area sensors are sophisticated multi-beam devices built from durable materials like semiconductors, ceramics, and polymers. Their key capabilities include precise area detection, wide coverage, environmental resilience, and easy integration with automation systems, making them indispensable for industrial object detection and safety applications.
