Elevators and the Photoelectric Effect

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  • on 01.07.09
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  • I've read that elevator doors operate according to the photoelectric effect--the electric eye opens the doors if something interrupts its light beam. I'm writing a story in which a character uses his knowledge of this effect to rig an elevator to open on certain floors and remain shut on others. I'm looking for some practical elevator science--and maybe a link or two detailing MacGyver-like scenarios--to justify that plot point. So, basically: What's the connection between the photoelectric effect and the operation of an elevator? If the occupant of an elevator knew of this connection, how could he apply that knowledge to affect an elevator's route?


  • Greetings Pempek: Would you looks at the page at http://www.simplexgrinnell.com/news_events/ia/fire/03c1g.jsp and let me know if this is the type of information you are seeking? It will help me determine where to focus. Best regards, journalist-ga SEARCH STRATEGY: "photoelectric detector" technology research "photoelectric detector" elevator problem "photoelectric sensor" technology research "photoelectric sensor" elevator problem


  • Journalist, The article on that page mentions the photoelectric effect, but only in passing, and within the context of the history of fire detection, which doesn't really help me. I guess I'm looking for two things: First, how exactly is the photoelectric effect applied in elevator technology? In my basic searches I've found a few sites that state briefly that "Einstein's theories made elevators and automatic doors at supermarkets possible," but none that really lay it out: "Here's how the photoelectric effect works, as illustrated by the electric eye in a common elevator." Second, are there any stories, anecdotal or hypothetical, of people re-routing an elevator car by adjusting the electric eye? The absolute ideal, and I'm doubtful I'll find this exact thing, would be step-by-step instructions--like those Worst-Case Scenario books that enumerate the steps to fending off an alligator or hot-wiring a car--that take me through how a person could scramble or disable an elevator car by tooling with the light beam. This is all in the interests of a fictional story: A physics student being chased through a building needs to make sure the elevator car containing his pursuers never arrives at the ground floor (or the doors never open once it does). It's a weird question, I know, but any leads would be great. Thanks.


  • I located a magazine called "Elevator World" at http://www.elevator-world.com/ that offers a one month subscription to their reseach center for $15.00 - see http://research.elevator-world.com/ See https://www.elevator-world.com/research_sub.htm#subscribe for the details. Their main subscription page reads in part ""The ELEVATOR WORLD Research Center is a self-service research database offered free of charge to current ELEVATOR WORLD subscribers." I don't know that it would help you but it might be worth the investment. There's also an information request form at http://www.elevator-world.com/findpart/door_equipment.htm that might be helpful. ********* A college prank concerning an elevator master key is located at http://www.ae.utexas.edu/~london/humor/CollegePracticalJokes.html - don't know if it might help... "The father of my dorm roommate worked as a repairman for the Otis Elevator Company. One weekend, I stayed with my roommate at his parent's home. While talking with his father, we learned an _amazing_ fact: almost all escalators are reversible for use in breakdowns or emergencies; there is usually a key-operated reversing switch located under the handrail at each end of the escalator. We also learned a second _amazing_ fact: most all Otis elevators and escalators use the _same_ key." ********* The specs for a photoelectronic switch at http://www.hokuyo-aut.jp/pdf/PE2.pdf may be of assistance. I found it at http://www.hokuyo-aut.jp/products/p_sensor.htm where there are a few photoelectronic switches. ********* Fiberoptics regarding an elevator "The fibre optic control unit has two connections whose function can be set e.g. for antivalent or additional warning output signal. Moreover, one of them can also be used as an input. As a result, the switching signal of the input can be connected with the optical input. Such features allow the unit to take over simple tasks of an open loop control: With the so-called latch the electric output signal follows the optical input for a start. When applying the electric latch signal one can freeze the last status and process it at any later time. "In addition, the sensor can operate like an edge triggered D flip-flop. With the active pulse edge the currently valid switching status is transferred to the output and maintained through to the next active edge. This function can be used when objects are to be detected at a defined time only. Logic operations can be carried out as well: The output switching signal is high when the input is activated AND the sensor detects an object simultaneously. This feature can be used if events are to be detected in a given time window. However, it also allows to link the signals of two photoelectric sensors, e.g. for monitoring an elevator. Its doors will only close if the light path of both sensors is free." From http://www.leuze.de/english/presse/pm/p12.htm ********* From http://www.amperite.com/examples.htm "ELEVATOR DOOR CONTROL - It is necessary that an elevator door's closing be delayed for a specified time after the last passenger has entered or left the elevator. The triggered delay on release timer can be used, in conjunction with a photoelectric sensor, to delay the closing of the door." ********* LAMBDA 3D protection system (a diagram is shown with brief explanation) http://www.unitecparts.com/portfolio/udoorpro.html According to http://www.scanelecsz.com/photosen.html there are four types of photoelectric sensors: "Photoelectric switches can be divided into four groups according to their functions. These four groups are through-beam switches, retro-reflective switches, diffuse switches, and fiber-optics with amplifiers. Photoelectric switches are used to detect various material at long ranges by non-contact sensing and are manufactured to the highest specifications and quality." There are diagrams of each on that page. If you were not aware that there was more than one type, is there a particular one you would like researched? I hesitate to post an answer until you are satisfied with the results. Best regards, journalist-ga SEARCH STRATEGY: "photoelectric sensor" elevator door "photoelectric sensor" failure "photoelectric sensor" elevator -fire "photoelectric technology" elevator -fire "elevator research" photoelectric "photoelectric research" elevator -fire "elevator technology" photoelectric elevator photosensor technology "elevator photosensor" "photoelectric elevator"


  • Those links are helpful, thanks. The description of the different switches is good. I think that's as much background as I need on electric eye functionality. I'll probably subscribe to Elevator World's research center, as well. If you came across any other anecdotal sites--along the lines of the college prank--those would be the most useful. If not, don't sweat it. I appreciate your help.


  • Greetings again Pempek: I'm delighted you found my research of assistance. I apologize for posting my last comments in the Clarification section as the more appropriate place would have been in the Comments section. I did find a reference to an elevator prank regarding Krazy gluing the floor buttons. I don't know how this might work for your story but...http://www.prank.org/archive_cat.php4?catID=39 I also found a wonderful story attributed to Peter Bogdanovich at http://www.scripting.com/mail/mail970717.html "When the first person got on with them, Hitch [Alfred Hitchcock] would spontaneously act like they were continuing a conversation by saying something along the lines of, "..and it was the most disgusting thing I have ever seen!" As people got on at each floor, Hitch would raise the odds: "... and blood was spurting out of his mouth! Blood! Gushes of it!" Finally, when they were nearing the bottom, Hitch would say "... and you know what he said to me? He raised his head up and his last dying words were..." *ding!* and everyone would have to get out of the elevator." ;) Tamarac Plaza "Elevator Malfunction" page - what to do http://www.propertysitesonline.com/tamarac/procedures/elevator.asp I located a parody page of "elevator tips" and it mentioned (don't know if true) "Sometimes, photoelectric sensors are only located near the center of the elevator door." That got me to thinking that the placement of the sensors in your story might be helpful with the action. The parody site is at http://www.monzy.com/elevator/ ********* On a search of "electronic eye" malfunction, I did locate a few interesting links: http://home.wlu.edu/~wendelb/Torts/1999final2b.htm There is mentioned "The servicing procedures require inspection of the eye mechanism and the bumpers; these were inspected and found to be working normally. Nick Shay, the director of safety for the Fix-It Company suggested that the problem might be with elevator's internal diagnostic computers. He said many elevator manufacturers used computer chips manufactured in the 1960's, which used two-digit dates to represent the year (using "65" for "1965," for example). Unfortunately, this engineering technique, which was necessary at the time to conserve expensive processing power and memory resources, led to what became known as the "Y2K" bug. As the date changed from December 31, 1999, to January 1, 2000, the two-digit date changed from 99 to 00, confusing the chips into thinking the date was January 1, 1900. In some cases, Shay said, it is conceivable that the date function could cause the elevator to malfunction. Shay thought that the electronic eye and the bumper pad sensors may have turned off at midnight, thinking it was January 1900." From an article about fuzzy logic at http://www.simplecodeworks.com/KSCO/book/chapter7.htm "Even elevators are becoming fuzzy. Companies such as Otis are working on the development of smart elevators -- devices that employ fuzzy logic to adjust to the level of traffic. By knowing how many passengers are currently in each elevator, which floors have passengers waiting to board, and the locations of all of the elevators currently in use, an optimum strategy of operation can be dynamically achieved." From another law case at http://lawlibrary.rutgers.edu/courts/appellate/a6425-98.opn.html "The doors had two safety devices: (1) a rubber safety edge running along the side of the doors, which was designed to retract upon contact, and (2) electric eyes in the top and bottom sides of the doors which would reopen them if the beam was broken by an object in its path. The evidence indicated that these safety devices were not foolproof. Both safety devices were functional only if an individual or object was located between the elevator doors. The hard edge of the exterior portion of the door could come in contact with an object or person without activating either the electronic eye or the safety edge." Then this from the same report as above: "In testing the elevators, Farrell would exert pressure on the safety edge to ensure that the doors would retract. In addition, he would periodically check the electric beams by using a voltage meter. The elevator in question was checked shortly before and shortly after the accident and was found to be in proper working order." You may consider the plot device of substituting a "seemingly functioning" voltage meter for use by a minor character - the worker thinks the beam is okay because the "sabotaged" voltage meter shows it's okay. Then your main character could rig all he wanted without the photoelectric beam being in use. ******* Here follows the sum of my previous research: I located a magazine called "Elevator World" at http://www.elevator-world.com/ that offers a one month subscription to their reseach center for $15.00 - see http://research.elevator-world.com/ See https://www.elevator-world.com/research_sub.htm#subscribe for the details. Their main subscription page reads in part ""The ELEVATOR WORLD Research Center is a self-service research database offered free of charge to current ELEVATOR WORLD subscribers." I don't know that it would help you but it might be worth the investment. There's also an information request form at http://www.elevator-world.com/findpart/door_equipment.htm that might be helpful. ********* A college prank concerning an elevator master key is located at http://www.ae.utexas.edu/~london/humor/CollegePracticalJokes.html - don't know if it might help... "The father of my dorm roommate worked as a repairman for the Otis Elevator Company. One weekend, I stayed with my roommate at his parent's home. While talking with his father, we learned an _amazing_ fact: almost all escalators are reversible for use in breakdowns or emergencies; there is usually a key-operated reversing switch located under the handrail at each end of the escalator. We also learned a second _amazing_ fact: most all Otis elevators and escalators use the _same_ key." ********* The specs for a photoelectronic switch at http://www.hokuyo-aut.jp/pdf/PE2.pdf may be of assistance. I found it at http://www.hokuyo-aut.jp/products/p_sensor.htm where there are a few photoelectronic switches. ********* Fiberoptics regarding an elevator "The fibre optic control unit has two connections whose function can be set e.g. for antivalent or additional warning output signal. Moreover, one of them can also be used as an input. As a result, the switching signal of the input can be connected with the optical input. Such features allow the unit to take over simple tasks of an open loop control: With the so-called latch the electric output signal follows the optical input for a start. When applying the electric latch signal one can freeze the last status and process it at any later time. "In addition, the sensor can operate like an edge triggered D flip-flop. With the active pulse edge the currently valid switching status is transferred to the output and maintained through to the next active edge. This function can be used when objects are to be detected at a defined time only. Logic operations can be carried out as well: The output switching signal is high when the input is activated AND the sensor detects an object simultaneously. This feature can be used if events are to be detected in a given time window. However, it also allows to link the signals of two photoelectric sensors, e.g. for monitoring an elevator. Its doors will only close if the light path of both sensors is free." From http://www.leuze.de/english/presse/pm/p12.htm ********* From http://www.amperite.com/examples.htm "ELEVATOR DOOR CONTROL - It is necessary that an elevator door's closing be delayed for a specified time after the last passenger has entered or left the elevator. The triggered delay on release timer can be used, in conjunction with a photoelectric sensor, to delay the closing of the door." ********* LAMBDA 3D protection system (a diagram is shown with brief explanation) http://www.unitecparts.com/portfolio/udoorpro.html According to http://www.scanelecsz.com/photosen.html there are four types of photoelectric sensors: "Photoelectric switches can be divided into four groups according to their functions. These four groups are through-beam switches, retro-reflective switches, diffuse switches, and fiber-optics with amplifiers. Photoelectric switches are used to detect various material at long ranges by non-contact sensing and are manufactured to the highest specifications and quality." There are diagrams of each on that page. If you were not aware that there was more than one type, is there a particular one you would like researched? SEARCH STRATEGY: "photoelectric sensor" elevator door "photoelectric sensor" failure "photoelectric sensor" elevator -fire "photoelectric technology" elevator -fire "elevator research" photoelectric "photoelectric research" elevator -fire "elevator technology" photoelectric elevator photosensor technology "elevator photosensor" "photoelectric elevator" "photoelectric detector" technology research "photoelectric detector" elevator problem "photoelectric sensor" technology research "photoelectric sensor" elevator problem elevator pranks "elevator door" malfunction "electronic eye" malfunction elevator "electric beam" malfunction elevator







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