Panachrome+<\/a>\u2019s design was to enhance safety for the visually, or mobility impaired. The visibility of the lit door edge enhances elevator safety by making it easier for passengers to determine its status. The visual cues can also be enhanced with audible voice cues. \u201cTalking doors\u201d that warn of closing doors are powered by built-in devices called voice annunciators.<\/p>\n\n\n\nVisual and audible cues, combined with 3D detection, reduce the chances of door damage, which is critically important where slow, heavy, or large objects are frequently entering lift cars.<\/p>\n\n\n\n
Examples include beds being pushed into hospital lifts, shopping carts in mall elevators, and baggage carts in airports or hotel lifts. In these circumstances obvious indications of door-edge movement give advance warnings of lift doors closing and may increase the time a passenger has to react and avoid an impact from closing elevator doors.<\/p>\n\n\n\n
Which light curtain is the best for your needs?<\/h2>\n\n\n\n When selecting a suitable light curtain for your lift door safety application it is important to consider several factors before making your decision. Diode count, number of beams and response time all play a part in determining the relative performance of a particular detector, and no feature should be judged in isolation. Let\u2019s look a little further into how each of these features work.<\/p>\n\n\n\n
Diode count<\/h3>\n\n\n\n The most important feature of a light curtain is the number of diodes it contains. This number is related to the smallest target that can be detected, particularly at the detector\u2019s edges. The mor diodes, the better the coverage.<\/p>\n\n\n\n
Number of beams<\/h3>\n\n\n\n When implemented correctly, diagonal beams will improve detection capability for smaller objects. Using a criss-cross pattern with four or five scans per diode will easily provide detection of 12mm (a child\u2019s finger) virtually anywhere between the detectors, except at the detector\u2019s edges.<\/p>\n\n\n\n
However, the stated number of beams is only available at wide separations and beams sometimes have such poor sensitivity that they are effectively redundant. Increasing beam counts further (three up and three down) will not improve performance. Beware: the number of beams can be used as a marketing ploy to demonstrate higher performance.<\/p>\n\n\n\n
Scanning speed<\/h3>\n\n\n\n Some light curtain manufacturers claim that offset diagonal beam systems and faster scanning provide performance benefits over rival technology. This is not actually the case.<\/p>\n\n\n\n
Imagine two detectors that use the same diagonal scanning method, right up to when the doors close. Detector A has 32 diodes while Detector B features 24 diodes.<\/p>\n\n\n\n
When the doors are approximately 600mm or more apart, detector A switches to an up-and-down two-beam pattern, giving four scans per diode. This dramatically increases the beam pattern density.<\/p>\n\n\n\n
The 50mm target is used as the benchmark for detector testing. The scans below compare performance with a 50mm target for Detectors A and B. A continuous red line indicates complete detection, while a broken line shows areas where targets are missed. As can be seen, there are many gaps for Detector B, but none at all for Detector A.<\/p>\n\n\n\n <\/figure>\n\n\n\nDetector B is particularly weak when the doors are near to closing \u2013 it has very poor close-in sensitivity with a relatively large target.<\/p>\n\n\n\n <\/figure>\n\n\n\nThe impact of these large gaps can indirectly extend the response time of the detector to several seconds. The doors will have to move quite a distance before an object, such as a hand, is detected. Detector B may scan very quickly, but that is pointless if it can\u2019t detect a person\u2019s hand for several seconds.<\/p>\n\n\n\n <\/figure>\n\n\n\nResponse time<\/h3>\n\n\n\n A detector\u2019s response time is a secondary factor. It has never been considered important to reduce response time in either the design or specification stages, as it is not critical to the detector\u2019s performance.<\/p>\n\n\n\n
Lift doors travel at slow speeds to avoid physical damage to passengers or equipment. Detectors are mounted between the inner and outer doors. The depth of the doors (front to back) means that there are several centimetres of unguarded space.<\/p>\n\n\n\n
Doors that close relatively quickly have a higher risk of hitting people or equipment (prams, wheelchairs, trolleys, etc.). A typical closing speed of a lift door is 0.5m\/s. This means in 100ms the door will only travel 5cm until the detectors are triggered. The doors themselves have inertia, so they will continue to travel a short distance even after a trigger.<\/p>\n\n\n\n
Detectors with improved scan or response times have very little perceived benefit to the end user. It is unlikely anyone would notice the door travel difference between a detector which can respond in 50ms and one which has a response time of 100ms.<\/p>\n\n\n\n
MEMCO detector products typically scan at around 1.5ms per diode, plus some overhead at the end of the scan for processing. This means that a standard 32 diode detector will have a scan rate of approximately 70ms. This is a worst-case time though. As soon as any beam is obstructed, the hardware output is triggered within a few milliseconds. The average response time will therefore be much less, in the order of 40ms.<\/p>\n\n\n\n
The Panachrome+ offers the added controller option which can be connected via CANBus<\/a> for remote monitoring<\/a>, offering an additional layer of safety and control.<\/p>\n\n\n\nSummary<\/h2>\n\n\n\n As mentioned above, having light curtains means you will most likely have a compliant setup. However, given the many alternatives in the market of lift door edges, it is important to remember what each feature really means and how it works, to ensure you are investing in safety measures which will suit your requirements.<\/p>\n\n\n\n
The main things to consider when deciding what technology to select for door edges for your lift setup are:<\/p>\n\n\n\n
\nThe number of diodes is a detector\u2019s most important feature. A 32-diode detector will detect smaller objects than a 24-diode model, and quicker.<\/li>\n\n\n\n The number of beams in a pattern determines the smallest sized object which can be detected anywhere in the field.<\/li>\n\n\n\n A detector\u2019s response time is a secondary factor. Door closing speeds mean the difference between response times of 45ms and 70ms has a negligible effect.<\/li>\n<\/ol>\n\n\n\nTo find out more about our market leading light curtain solution for optimal lift safety, please visit our Panachrome+ page<\/a>.<\/p>\n","protected":false},"excerpt":{"rendered":"Light curtains are critical to lift door safety, protecting passengers from door impacts. How do you choose the right light curtain for your lift setup?<\/p>\n","protected":false},"author":3,"featured_media":2999,"menu_order":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_eb_attr":"","inline_featured_image":false,"footnotes":""},"product_cat":[27],"_links":{"self":[{"href":"https:\/\/www.avire-global.com\/wp-json\/wp\/v2\/posts\/2990"}],"collection":[{"href":"https:\/\/www.avire-global.com\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.avire-global.com\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.avire-global.com\/wp-json\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/www.avire-global.com\/wp-json\/wp\/v2\/comments?post=2990"}],"version-history":[{"count":2,"href":"https:\/\/www.avire-global.com\/wp-json\/wp\/v2\/posts\/2990\/revisions"}],"predecessor-version":[{"id":3750,"href":"https:\/\/www.avire-global.com\/wp-json\/wp\/v2\/posts\/2990\/revisions\/3750"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.avire-global.com\/wp-json\/wp\/v2\/media\/2999"}],"wp:attachment":[{"href":"https:\/\/www.avire-global.com\/wp-json\/wp\/v2\/media?parent=2990"}],"wp:term":[{"taxonomy":"product_cat","embeddable":true,"href":"https:\/\/www.avire-global.com\/wp-json\/wp\/v2\/product_cat?post=2990"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}