An elevator light curtain is a kind of light-type elevator door safety protection device, applicable to passenger elevators, and freight elevators, to protect the safety of passengers. It consists of four main parts: the infrared transmitter and receiver installed on both sides of the elevator car door, the power box installed on the top of the car, and the special flexible elevator.

 
In the transmitter there are 32 infrared transmitter tubes, under the control of the MCU, the transmitter-receiver tubes are opened accordingly, scanning the car door area continuously from top to bottom, forming a dense infrared protection light curtain. When any of the light is blocked, the control system immediately outputs the open signal, and the car door stops closing and reverses to open, until the passengers or blocking objects out of the warning area before the elevator door can be closed normally, to achieve the purpose of safety protection, so that the elevator can be avoided to clip the occurrence of accidents

How to repair the elevator light curtain when it is broken?
An elevator light curtain uses a use of photoelectric induction principle and is made of an elevator door safety protection device, applicable to all elevators, to protect the safety of passengers in and out of the elevator. An elevator light curtain is installed in the elevator car door on both sides of the infrared transmitter and receiver and a special flexible elevator has three major components. For environmental protection and energy-saving needs, more and more elevators have omitted the power box. Some brands of light curtains also have to be sure to use the power box due to poor resistance to electromagnetic interference. But with the popularization of the concept of green elevator, power box-free light curtain is a trend. Because the 220V to 24V process is bound to lose a lot of energy.

 
Light curtain transmitter inside several infrared transmitter tubes, under the control of the MCU, the transmitter-receiver tube is opened in turn, a transmitter head emitted light is received by several receiver heads, forming a multi-channel scanning. Through this top-down continuous scanning of the car door area, a dense infrared protective light curtain. When any of these beams of light is blocked, the light curtain determines that there is an obstruction due to the inability to realize photoelectric conversion, and therefore outputs an interrupt signal. This interrupt signal can be a switching signal or a high and low-level signal.

 
The control system receives the signal given by the light curtain and immediately outputs the open signal, the car door stops closing and reversing open until the passengers or blocking objects out of the warning area after the elevator door can be closed normally, to achieve the purpose of safety and protection, to avoid elevator clamping accidents.
Elevator light curtain failure is generally manifested in the following areas:

 First, the elevator light curtain closing the door is a false action - not closing the door

 
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 circuit may be due to the following hardware failures:

1, the point of light is blocked by foreign objects - should check and remove the light curtain infrared light on the foreign body (such as luggage tags, paint stains, chewing gum, etc.), In such cases, just clear the light curtain light on the foreign body can resume operation.

 
2, light curtain for long-term use, or in the dusty, humid environment (especially during the renovation of the building), infrared transmitter/receiver light pipe will have dust, the need to clean up the dust, the elevator door can return to normal.

 
3, point of light damage - infrared light curtain due to continuous scanning, its infrared emission tube repeatedly undergoes current excitation, is more likely to damage the device. The infrared emitting light tube is damaged and should be replaced.

Second, the elevator light curtain closes the door is a false action-closing interruption

 
1, the elevator door closing process, infrared light curtain a beam of scanning is not received, or receiving intensity does not reach the set value, the system will trigger, and make the elevator door reversed open. If this is not caused by object obstruction, that is, the infrared light curtain malfunction. Elevator core damage will be in a certain position to cause the system to malfunction.

 
2, infrared light curtain transmitter/receiver conditions, are the main reason for infrared light curtain door closing process malfunction. An infrared light-emitting tube strength is low, or quality instability strength reduction, or due to the accumulation of dust, etc., will lead to false action in the closing process.

 
Third, the elevator light curtain does not move

 
Infrared light curtain in the elevator door closing process, although there is a block, but not triggered, resulting in danger. This is usually caused by the following reasons:
1, infrared light curtain scanning harness density is not enough, or scanning mode caused by the scanning blind spot

 
2, infrared sensitivity is not enough. The infrared light curtain in the elevator door is fully open, and the emission intensity should be the maximum. With the elevator door closed, infrared emission intensity should be reduced step by step (each level down to just received by the receiver, does not cause infrared light curtain malfunction for the lower limit), to the door all closed for the lowest. Otherwise, near the location, the infrared intensity is too large, and tiny objects can not be blocked, it will occur although there is blocking, but not action.

 
3, daylight or elevator background stray light in similar wavelengths of infrared light irradiation to the infrared receiver, resulting in although there are objects blocking, the infrared light curtain still sending a normal receive signal. This is particularly common in sightseeing elevators and outdoor elevator applications.