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Quantifying the resolution of safety light curtains
In various types of safety light curtain products on the market, an important selection parameter is the resolution. The resolution is typically quantified in millimeters (mm), such as common values like 14mm, 20mm, 30mm, and so on. These quantified indicators represent the gap between the sensing functions of the safety light curtain sensors.
Is it an intuitive classification or a misconception?
According to different resolutions, safety light curtains are usually classified as finger, hand, and body protection types, which are used to indicate the most suitable application scenarios. However, this intuitive classification method is often misunderstood. Many designers believe that they can directly select the type of light curtain based on the body parts that can be injured by the hazard source. However, such a matching method often does not meet the requirements of standards
The correct selection method for safety light curtains.
According to the European standard EN ISO 13855, the minimum distance of safety light curtains from the hazard source should be calculated by taking parameters such as the resolution of the light curtain, installation method, and system's stopping response time into consideration. Different formulas apply for vertical, horizontal, and angled installations. Only by considering the resolution of the light curtain, positioning method, stopping response time, and distance from the hazard source in a comprehensive manner can we adhere to the standard and choose the correct method.
For example, if the light curtain selection for a certain device is based on a matching method and a hand protection type is chosen. However, if the positioning of the light curtain in relation to the hazard source is restricted or if the system's stopping response time is too long, it is necessary to consider increasing the resolution of the light curtain to meet the requirements of EN ISO 13855.
