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Elevator knowledge: elevator light curtain repair

May 21, 2018

The elevator light curtain is a light-type elevator door safety protection device that is suitable for passenger elevators and freight elevators to protect the safety of passengers. The infrared transmitter and receiver installed on both sides of the elevator car door, the power box installed on the car top and a special flexible elevator are four major components.

    There are 32 (16) infrared emission tubes in the transmitter. Under the control of the MCU, the emission receiver tube is opened accordingly, continuously scanning the car door area from top to bottom to form a dense infrared protection light curtain. When any one of the beams is blocked, the control system immediately outputs the door opening signal, and the car door stops closing and reverses and opens until the passenger or the obstacle leaves the guard area and the elevator door can be closed normally, thereby achieving the purpose of security protection. It can avoid the elevator accident.

    The light curtain is always lit and does not close. After the replacement of the new light curtain, it is still lit. Door panel replacement, failure still exists.

    A. The elevator light curtain is always on how to solve the problem

    The light curtain will be bright, blocked or powered. If there is no problem with the output door machine, receiving light curtains is also a problem. That is the middle problem. The light curtain can be tested on the ground. Line interference can be ruled out and errors can be blocked in the middle. It is no longer possible to measure the black line that the light curtain outputs. Notice that the line has to be removed and the output is low. That is 0 volts. Black line, the output of the board is 24 volts. In the past few days I have just finished this kind of door light curtain. Prepare to write a new one.

    II. How to solve the problem of elevator light curtain

    1. Check if the light curtain has any object blocking. (Car light too bright will also affect the light curtain work)

    2. Judging the damage of the light curtain, removing the light curtain of the faulty elevator, and replacing it with the normal elevator, the light curtain has no problem. Then, after the replacement of the new light curtain on the problem elevator, the light curtain was still on. It was proved that the problem with this light curtain is not the cause of the light curtain.

    3. Determine the cause of the door panel, replace the door panel, the fault still exists.

    4. Check the input voltage of the light curtain plug. X16 is the power line and X15 is the signal line. The elevator is 24V and the voltage is normal.

    5. The problem of signal interference. The KONE light curtain was removed and tested on the ground. The use of micro-column light curtains can be used normally.

    Third, the fault solution:

    Reconnect the grounding cable of the door machine into the transformer and tighten the fault.

    Elevator light curtain maintenance tips

    In order to prevent the passenger elevator doors from catching passengers during the closing process, safety touch panels (or photoelectric or light curtains) are generally installed on the elevator car doors. Safety contact plate: It is a mechanical anti-clamping device. When the elevator is in the closing process, when the person touches the safety touch plate, the safety contact plate is retracted inwards to drive a micro switch in the lower part, and the safety contact plate switch action is controlled. The door turns in the direction of opening the door.


    Some elevators installed door optics (at least two points), one for the transmitter and the other for the receiver. When the elevator door is closed, if there is an object blocking the light, the receiving end can not receive the light source of the transmitting end, immediately drive the optoelectronic relay action, and the photoelectric relay controls the door to open in the opposite direction.

    Elevator light curtain:

    The same principle as electro-optics, but there are many launch and reception points.

    Fault status:

    Elevator door does not close phenomenon:

    The elevator cannot be turned off when it is in automatic position, or reversed when it is not turned off. It can be closed during inspections. Cause: The safety touch panel switch is broken, or it is stuck, or the switch is improperly adjusted. The safety switch touches the switch slightly when it is actuated. The door optoelectronic (or light curtain) is offset or blocked. Or door photoelectric no (elevator light curtain) power supply, or photoelectric (elevator light curtain) has been broken.

    The elevator light curtain is broken how to repair?

    The elevator light curtain is a kind of elevator door safety protection device made by using photoelectric induction principle. It is applicable to all elevators and protect the safety of passengers entering and leaving the elevator. The elevator light curtain is composed of three parts: an infrared transmitter and receiver mounted on both sides of the elevator car door and a dedicated flexible elevator. For environmental protection and energy saving needs, more and more elevators have saved the power box. Some brands of light curtains have to use power boxes because of their poor resistance to electromagnetic interference. However, with the popularization of the concept of green elevators, the power box-free light curtain is a trend. Because 220V to 24V is in the process of losing a lot of energy.

    There are several infrared emission tubes in the emission end of the light curtain. Under the control of the MCU, the emission and reception tubes are sequentially opened, and the light emitted by one of the emission heads is received by a plurality of receiving heads to form a multiplexed scanning. By continuously scanning the car door area from top to bottom, a dense infrared protection light curtain is formed. When any one of the lights is blocked, since the photoelectric conversion cannot be realized, the light curtain judges that there is an occlusion, so an interrupt signal is output. This interrupt signal can be either a digital signal or a high or low signal.

    After the control system receives the signal given by the light curtain, it immediately outputs the door opening signal, and the car door will stop closing and open in reverse until the passengers or the obstacles leave the guard area and the elevator door can be closed normally to achieve the purpose of security protection. Avoid elevator accidents.

The failure of elevator light curtains generally manifests itself in the following aspects:

    One, elevator light curtain closing is wrong - not closed

    The elevator light curtain is a closed-loop protection system. When the infrared beam detection circuit is interrupted, the elevator door will not close. The abnormal interruption of the infrared beam detection loop may be due to the following hardware failures:

    1. The light spot is blocked by foreign matter – Foreign objects (such as luggage tags, paint stains, chewing gum, etc.) on the infrared light path of the light curtain should be inspected and removed. In such cases, it is only necessary to clear the foreign matter on the light path of the light curtain to resume operation.

    2. When the light curtain is used for a long time, or when it is used in dusty and humid environments (especially during the interior decoration of the building), there will be dust on the infrared transmitter/receiver light pipe. The dust needs to be cleaned and the elevator door can be restored to normal.

    3. Damage to the light spot – Due to the continuous scanning of the infrared light curtain, the infrared light emitting tube is repeatedly subjected to current excitation, which is a relatively easy to damage device. Infrared emitting light pipe is damaged and should be replaced.

    Second, the elevator light curtain is closed by mistake - shut down

    1. During the elevator door closing process, a certain beam scan of the infrared light curtain is not received, or the received intensity does not reach the set value, and the system will trigger and cause the elevator door to open in reverse. If this is not caused by the obstruction of the object, it is the malfunction of the infrared light curtain. Damage to the core of the elevator will cause the system to malfunction in a certain position.

    2. The infrared light curtain launch/receive condition is the main reason for the malfunction of the infrared light curtain closing process. A certain intensity of the infrared light emitting tube is low, or the quality is unstable, or due to dust accumulation, etc., can cause malfunction in the closing process.

    Third, the elevator light curtain does not move

    During the closing process of the elevator, the infrared light curtain is blocked, but it does not trigger, causing danger. This is usually caused by the following reasons:

    1, infrared light curtain scanning harness density is not enough, or scan mode caused scan blind

    2, infrared sensitivity is not enough. When the infrared light curtain is fully open at the elevator door, the emission intensity should be the maximum. With the elevator door closed, the infrared emission intensity should be reduced step by step (each level is reduced to just be received by the receiver, does not cause the infrared light curtain to malfunction as the lower limit), to the door is completely closed when the lowest. Otherwise, in the close distance, the infrared intensity is too large, and the tiny objects cannot be blocked, but there will be a blockage but no action.

    3. Infrared light with similar wavelengths in daylight or elevator background stray light is radiated to the infrared receiver, causing the infrared light curtain to still emit a normal receiving signal despite the object being blocked. This is especially common in sightseeing elevators and outdoor lift applications.

This article label: elevator elevator light curtain elevator light curtain repair