What is the important role of the light curtain (Car Door Detector/Sensor) in the elevator?

The elevator light curtain consists of three parts: the infrared transmitter and receiver installed on both sides of the elevator car door and the special flexible cable. It is a door system safety protection device.

The operating principle of elevator curtain is as follows:

There are several infrared transmitting tubes inside the transmitting end of the optical screen. Under the control of the micro-control unit, the transmitting receiving tube is opened successively, and the light emitted by one hair color is received successively by multiple receiving heads, forming a multipath scan. It will be formed a dense infrared protection screen through this top-down continuous scanning car door area. When any beam of light is blocked, because the circuit at the back end of the receiving head cannot realize photoelectric conversion, the light curtain is judged to be blocked, so an interrupt signal is output to the portal machine. This interrupt signal can be a switch or a high or low level signal. After receiving the signal given by the light curtain, the elevator door machine will immediately output the opening signal, and the car door will stop closing and reverse open, and the elevator door will not close normally until the passenger or barrier leaves the warning area, so as to achieve the purpose of safety protection and avoid the occurrence of the elevator sandwiching accident.


The above mentioned principles of the elevator screen work have several basic concepts:

First of all is the quantum efficiency of photoelectric. There are two technologies to choose from, CMOS and CCD. Anyone who has ever played with a camera knows these two terms. Generally, the camera in a mobile phone is CMOS, while the camera in a digital camera is CCD. The CCD technology is complex, so the cost is definitely higher than that in the case of the same resolution. CMOS has a feature. Under good light, the quantum efficiency of photoelectric conversion is high, but if the light is bad, the conversion rate is low, and the imaging quality is sharply reduced. So phones that use CMOS cameras lose image quality dramatically at night. Limited to the cost relationship, infrared screen receiver head is used in CMOS technology. The direct result of low efficiency of photoelectric conversion is that the screen is easy to misjudge. In order to improve the efficiency of photoelectric conversion, the common solution is to increase the transmission power. The transmitter head is easy to damage under high power condition.


Another concept is the number of eyes and the number of beams. Many people now judge the quality of the screen simply by the number of beams, and many tender documents simply say “require more than 150 beams”. This is actually a wrong idea. Light eyes, usually in pairs, one launch, one reception. The light curtain USES the scattering principle to realize multipath scanning. Due to the scattering property of light, the light emitted by one emitter can cover up to five receiving heads at a distance, scanning one by one. Of course, the top end and the bottom end of the hair receiving head, there will be three beams of light because of the scattering Angle of the physical reasons can’t receive. So 16 of the first 5 scans minus 3 of the top and the bottom 3 of the top is 16*5-6=7


What is the important role of the light curtain (Car Door Detector/Sensor) in the elevator?

What is the important role of the light curtain (Car Door Detector/Sensor) in the elevator?

As the protective device of the door system, the most important evaluation factor is reliability.

  1. The IP rate
  2. Anti-interference ability
  3. Light resistance


Light curtain as an electronic product, the reliability of optical screen also depends on its electromagnetic compatibility, and its strong electromagnetic tolerance (EMS) is a key index to measure its reliability. Faulty elevator doors account for a large proportion of casualties. “A protective device should automatically re-open the door when a passenger is struck or will be struck by a door leaf as he/she passes through the entrance of the car while the door is closed,” according to both international and regulatory requirements. Therefore, all the lift out of the factory will always have a door protection product – light curtain.

OTIS Elevator BS34A Braille Push Button (Titanium Black/Titanium Golden) Be Sold To United Arab Emirates

In elevator industry, the push buttons are generally divided into floor numbers button, door open/close button, door hold button, alarm button

Floor Numbers Button: As the name implies, it is used to select the destination floor. When the passenger enters the elevator car, the floor should be selected by pressing the button of the destination floor, if the light of button is on, which proves that the floor has been registered and the floor selection is successful. The elevator car will stop in order in the same direction after door closing.

Door Open Button: At present the door of elevators are driven by the power automatically in general configuration, the door open button is used to execute the elevator door opening operation. When the passenger is inside the elevator car, the elevator door is closing automatically, but if other passenger is still moving into the car, at the moment, the door can be opened automatically if pressing the door open button. In other situation, when the door is fully closed and the elevator is not in running, pressing the door button can make the door open again automatically.

Door Close Button: The Button is used to control elevator door closing automatically. When all passengers are ready in the elevator car completely, and the elevator light curtain or safety touch sensor is not screened, the elevator door will be closed automatically after a preset time. In order to improve the efficiency, the passengers could press the door close button to close automatically ahead of time.

Alarm Button: When passengers are stuck in the elevator car, they can ask helps from the duty room or monitoring room by pressing the alarm button and get timely rescue.

Intercom Button: When passengers are stuck in the elevator car, they can communicate by telephone with the duty room or monitoring room by pressing the alarm button. Just one time pressing, after the other member is connected to the interphone device, the two members can have a long conversation. If the conversation is interrupted, you can press this button again to continue to request a call.

Door Hold Button: Some freight elevators are also equipped with a door hold button, which is generally marked with ‘delay’ or ‘Hold’ words. The elevator doors open and remain open for a while for loading and unloading after the button is pressed.

The United Arab Emirates (UAE), sometimes simply called the Emirates, is a country in Western Asia at the southeast end of the Arabian Peninsula on the Persian Gulf, bordering Oman to the east and Saudi Arabia to the south, as well as sharing maritime borders with Qatar to the west and Iran to the north. The sovereign absolute monarchy is a federation of seven emirates consisting of Abu Dhabi (which serves as the capital), Ajman, Dubai, Fujairah, Ras al-Khaimah, Sharjah and Umm al-Quwain. Each emirate is governed by a ruler; together, they jointly form the Federal Supreme Council. One of the rulers serves as the President of the United Arab Emirates. In 2013, the UAE’s population was 9.2 million, of which 1.4 million are Emirati citizens and 7.8 million are expatriates.

Our customer is from UAE requirements are the push button surface styles are black finishing & golden finishing, and background light is white, yellow, or blue.

Video of Real BS34A Push Button


Pictures of Real BS34A Push Button

OTIS BS34A Braille Push Button with Titanium Black / Titanium Golden (Front Side), OTIS BS34A Push Button Manufacturer

OTIS BS34A Braille Push Button with Titanium Black / Titanium Golden (Front Side)

OTIS BS34A Braille Push Button with Titanium Black / Titanium Golden (Back Side), OTIS BS34A Push Button Factory Price

OTIS BS34A Braille Push Button with Titanium Black / Titanium Golden (Back Side)

How to avoid elevator car door failure?

The failure of elevator door system accounts for a large proportion of the total failure of elevator, among which the door mechanism is the most frequently running system in the work of elevator, which is directly related to the safe and reliable operation of elevator. The failure rate of car door system also accounts for a considerable proportion in the failure rate of door system. The main reason is that the installation technology of door system is not up to the design requirement. The interpretation of the car door below is shared.

  1. The door opener, car door, safety security sensor, and the installation of the door knife have been completed by the installation team at the time of maintenance.
  2. The adjustment of car door is the premise of door system adjustment. Only after the door is adjusted, will the door be calibrated.
  3. First remove dust from the door with a pair of fan, and then grind the track of the door with more than 300# sandpaper to ensure the flexible operation of the door.
  4. The door must be adjusted to:
  • The distance between the door plate and the floor sill is 4mm;
  • The distance between the door and the front wall of the car is 4-6mm (not too small). Check method is to use just ruler on two pieces of door plank up and down side, whether it is balance.
  • The front and side of the door must be vertical to ensure that the door is properly sewn when it closed, meanwhile when opened; it joined to the front of the car. After adjusting the car door, you can open and close the door manually. The whole switch process should be easy and smooth.
  1. Adjust the security sensor and light curtain. When the contact plate is extended, the contact plate’s protrusion is suitable for 30mm to 50mm, and the same amount of two contacts is used. The light curtain should be even, and no abnormal trigger should occur during the rapid opening and closing process, especially for the rear light curtain to keep clean.
  2. Adjust the opening knife: step 1: make sure the distance between the door knife and the floor sill of the hall door is 7mm, and ensure the vertical direction; Step 2: determine the distance between the blade of the door knife and the decoupling roller of the door lock of the hall door is about 7mm. Check running elevator to observe all the way, depends on the clearance of most hall door, can be in a small range on the left, right, right amount translation car door assembly (this method is not applicable to double synchronous door knife of double folding door such as TD3200 car elevator door machine); Step 3: the two surfaces of the door knife blade, namely the one of the rollers, must be vertical. Step 4: check that when driving the door, the blade should not make abnormal sound.
  3. The speed of opening and closing shall be adjusted when the door of the sedan chair drives the door of the hall. The speed shall be controlled at about.070m/s. The speed of opening and closing doors should be gentle according to the elevator’s different acceleration and deceleration.

What are the elevator safety circuit switch parts?

In order to ensure the elevator running safely, there are many safety parts on the elevator. The elevator run based on each safety component in normal condition, otherwise it will be stopped. The so-called safety circuit is to install a safety switch in each safety elevator part, all safety switches are connected in series, controlling a safety relay. Only when all the safety switches are on, the safety relay is closed, and the elevator can run electrically.

Safety component switch of common elevator safety circuit:

  1. Speed limit switch (including speed limiter cut rope switch) – when the elevator at a faster rate than the rated speed value must be at least equal to the rated speed (115%), its action can lead to safety clamp work safety device.
  2. Maintenance switch — divided into control cabinet maintenance switch, car maintenance switch and car top maintenance switch. The three repair switches lock each other to prevent wrong operation and ensure the safety of maintenance personnel.
  3. Bottom pit buffer switch — this device is located at the bottom of the well path and is set at the bottom limit position of the car and the counterweight stroke. In the buffer (an elastic buffer safety device used to absorb the car and against heavy kinetic energy). After the action, the elevator cannot operate normally until it returns to its normal elongation position.
  4. Upper and lower limit of interlock switch, when the car running beyond magnetic induction device, flat layer in capsules or have not contact with buffer before the weighing device, forced to cut off the main power supply and control power of the safety device of automatic reset. The device is located as close as possible to the end of the station when working without error in the dangerous position of movement. It shall operate in the cage or before heavy (if any) contact with the buffer and maintain its action status during compression of the buffer. For the forced drive elevator, the limit switch is used to cut off the power supply circuit of the motor and brake. The elevator cannot resume operation automatically after the limit switch action.
  5. Safety clamp switch — check whether the speed limiter is operating. When the speed limiter moves, then a mechanical safety device that keeps the car or the car in a static state and can clamp the guide rail.
  6. Safety window switch — means that the car safety window is equipped with a safety device for manual locking. If the lock fails, the device can stop the elevator. The elevator will not be able to resume operation until it is re-locked.
  7. Door and door interlock switch — door and door of the hall are locked after closing, and the control loop is connected at the same time. The safety device of mechanical & electrical interlock safety device can only operate the car. Its function is that when the elevator car stops at a certain floor station, the door of the other floor station is effectively locked, and if the elevator is opened, it cannot start or keep running normally.