Elevator light curtain is a kind of elevator door safety protection device made of photoelectric induction principle. It is suitable for passenger elevator, freight elevator and other elevator types to protect the safety of passengers entering and leaving the elevator. Elevator light curtain is composed of four parts: infrared transmitter and receiver installed on both sides of elevator door, power box installed on car roof and special flexible cable. Considering the need of environmental protection and energy saving, more and more elevators have already saved the power box. Some brands of elevator light curtain because of the poor anti electromagnetic interference ability, which must use power box. But with the national advocacy, development and popularization of the concept of green elevator, light curtain without power box will also be a trend. Because a lot of energy must be lost in the process of converting 220V to 24V. It’s hard to imagine the loss of electric energy in a month.
There are several infrared transmitting tubes in the light curtain transmitting end. Under the control of MCU, the transmitting and receiving tubes are opened in batches, and the light emitted by each transmitting hair is absorbed by multiple receiving heads to form multi-channel scanning. Through this kind of top-down continuous scanning car door area, forming a dense infrared protection light curtain area. When any beam of light is blocked, because photoelectric conversion cannot be realized, the light curtain is judged to be blocked, so an interrupt signal will be output. This interrupt signal can be either a switching value signal or a high and low level signal. When the control system receives the signal from the light curtain, it immediately outputs the door opening signal, and the elevator door stops closing and reversely opens, until the passenger or the barrier leaves the warning area, the elevator door can be closed normally, so as to achieve the purpose of safety protection, so as to avoid the occurrence of the elevator clamping accident.
Here is a detailed description of the operation of elevator light curtain in three states:
1. When there is no intruder in the protection area, the receiver of the sensor is in the light receiving state. At this time, the communication light (red light) of the receiver is off, and the emission indicator light (yellow light) is on. At this time, if the protected switch of the device is pressed, the device can operate normally.
2. When an object (which can be detected or scanned) intrudes into the protection area, the communication light (red light) of the receiver is on (it may be that the receiver is in the blackout state or the optical communication is blocked), then the protected equipment is under control and in the forced stop state.
3. When the object is not in the protection area or exits the protection area, the safety light curtain of the elevator will return to 1 state, and the equipment will continue to work normally.