What is A Safety Light Curtain? Principles of Operation and Industrial Applications
- Share
- publisher
- Zoe
- Issue Time
- Dec 2,2024
Summary
Safety light curtains, as highly effective safety protection devices, are widely used in industrial automation, logistics, and elevators. Through proper selection, precise installation, and timely maintenance, they can effectively reduce accidents, ensure personnel safety, and enhance production efficiency.
What Is a Safety Light Curtain and What Does It Do?
A safety light curtain consists of an emitter and a receiver. The emitter emits modulated infrared light, forming a light curtain within the protected area. The receiver is responsible for detecting the emitted light. When an object (such as a human body or other opaque object) enters the light curtain area and blocks the light beam, the receiver detects the change in the light signal and triggers an output signal. This causes the connected equipment (such as a machine control system) to respond with a safety action, typically by stopping the machine's operation to prevent injuries.
Applications of Safety Light Curtains
Industrial Machinery
Safety light curtains are widely used in press brake machines and other equipment. For example, by installing a safety light curtain in front of a press brake die, if a worker's hand or other body part enters the pressing area, the light curtain will immediately detect the interruption of the light beam and stop the press brake's operation, preventing injury to the worker. Safety light curtains can also be used in the clamping area of injection molding machines to prevent operators from being pinched when the mold closes.
Automated Logistics
In automated storage systems, safety light curtains can be installed on both sides of the conveyor belt. If an item falls or a person approaches the danger zone, the light curtain will detect it in time and stop the conveyor belt, ensuring the safety of both goods and personnel.
Elevator Industry
Small safety light curtains can be installed at the edges of elevator doors. If an object (such as a passenger's hand or foot) blocks the light beam during the elevator door closing process, the light curtain will immediately stop the door from closing and reopen it to prevent the passenger from being trapped.
Selection of Light Curtains
🚩 Safety Level of Light Curtains
Safety light curtains are classified into different safety levels based on the potential risk posed by the equipment to personnel. The two most common safety levels are:
✅ Type 2 Safety Light Curtains: Typically used for applications with lower risks, where the potential for severe injury is minimal. These are often chosen for environments where only minor injuries could occur.
✅ Type 4 Safety Light Curtains: Designed for high-risk environments where the consequences of a failure could result in severe injury or fatality. These are required in applications where machinery poses a significant hazard to workers, such as in press machines or other heavy industrial equipment.
When selecting a safety light curtain, it is essential to assess the risk level of your specific application. For high-risk machines, a Type 4 safety light curtain should be selected to ensure the highest level of protection.
🚩 Importance of Beam Spacing
The beam spacing of a light curtain determines the minimum size of the object that can be detected. According to ergonomic data, the diameter of an adult's finger is at least 14mm, the thickness of the palm is 30mm, and the diameter of the wrist is 40mm. Different manufacturers may use different terms, such as resolution or beam spacing. Specific data can be found in the manufacturer's instructions. For example, DADISICK's QZ series safety light curtains offer beam spacings of 10mm, 14mm, 20mm, 30mm, 40mm, 80mm, and 200mm.
🚩 Difference between Safety Light Curtains and Safety Grids
Safety grids consist of an emitter and a receiver, but the beam spacing is larger, typically 300mm to 500mm. They are designed for larger-scale peripheral protection and are suitable for long-distance protection, but cannot replace the more closely spaced light curtains for short-range protection. DADISICK's QSA series safety grids have a maximum detection distance of 45 meters.
Working Principle of Light Curtains
Each safety light curtain consists of an emitter and a receiver and needs to be paired and aligned. The emitter sends infrared beams to the receiver, and the receiver only recognizes these specific beams to reduce interference from ambient light. DADISICK's safety light curtain series are usually sold as a complete set, including emitters, receivers, cables, and standard mounting accessories. Additional mounting accessories can be selected based on the application environment of the light curtain.
Equipment Response after Light Curtain Beam Interruption
1️⃣Equipment Shutdown:
When the safety light curtain beam is interrupted, the connected equipment will stop operating. For example, in an industrial press brake, when the beam is blocked, the control system receives an interruption signal, triggers the safety braking mechanism, and cuts off the power system. This mechanism effectively prevents personnel from being injured by mechanical parts such as the press brake ram during equipment operation.
2️⃣ Alarm:
After the safety light curtain beam is interrupted, the alarm device will be activated, usually manifested as an audible and visual alarm. The buzzer or alarm sound attracts the operator's attention, and the indicator light of the light curtain may also flash to indicate the occurrence of a fault, helping maintenance personnel locate the problem.
3️⃣ Data Recording and Feedback:
Modern safety light curtain systems have data recording functions, recording information such as the time, location, and duration of beam interruptions. This data can be stored in the light curtain itself or uploaded to a central monitoring system to help safety managers analyze the trends of fault occurrences and optimize production environments or safety management measures.
4️⃣ Recovery Process:
When the object moves away from the safety light curtain beam, the system will automatically detect the restoration of the beam. Some systems may automatically restart the equipment, while others require manual confirmation before resuming. This operation aims to avoid safety hazards when restarting the equipment. DADISICK's safety light curtain series have polarity, short-circuit, overload protection, and self-checking functions to ensure that no erroneous signals are sent to the equipment in case of a fault.
Advantages of Safety Light Curtains
✅ Non-contact Detection: Safety light curtains use photoelectric principles for non-contact detection, avoiding damage to the detected object and reducing equipment wear and tear and failures.
✅ Fast Response: Safety light curtains can detect objects entering the light curtain area within milliseconds, especially suitable for high-speed operating equipment, effectively preventing accidents.
✅ Flexible Installation: Safety light curtains can be flexibly installed according to the shape of different equipment and the size of the danger zone, supporting various installation methods such as bracket installation and suspension.
✅ High Customizability: It can be customized according to protection height, protection distance, and number of beams to meet the safety requirements of different production lines and equipment.
Related Safety Light Curtains
Disclaimer: The brands and specifications shown on this page are for product comparison and selection purposes only. Our safety light curtains are manufactured by DADISICK and are not official products of the listed brands. DADISICK offers replacements compatible with these brands' products. We do not own the rights to any of the mentioned brands. If you need to purchase official brand products, please contact the brand official representative.