Views:0 Author:Site Editor Publish Time: 2021-05-14 Origin:Site
Visible light refers to the visible light wave domain from 400nm (purple light) to 700nm (red light), and the wavelength between 760nm and 1mm is called infrared, which is a kind of light invisible to the naked eye. With the help of some optical equipment, we can feel the infrared. Usually, the infrared camera will convert it into visible green light after receiving the infrared. Our naked eye will never see the real infrared. The glasses that can see infrared rays often appear in movies are also nonexistent.
⭐The difference between 850nm and 940nm
1. 850nm or 940nm is about the wavelength emitted by the LED chip. The unit is nm, belongs to infrared light. First of all, the wavelength is different;
2. Normally the higher the wavelength value, the lower the VF value of forward voltage drop under the same current. Under the condition of 20mA current, the VF value of 850nm is about 1.35-1.55v; The VF value of 940nm is about 1.10-1.25v, of course, the VF value will be different with different current;
3. There is a red explosion in 850nm, but there is no red explosion in 940nm. The so-called red explosion refers to the visible red spots on the chip when the infrared lamp is working. So if you need invisible one, 940nm is a good choice. However, some customers will use the black colloid 850nm to cover up the red explosion, but if you pay more attention, the red explosion is still visible;
4. The radiation intensity of 850nm is about 2-3 times higher than that of 940nm. If the radiation intensity is higher, the brightness will be higher;
5. In the incoming test, 850nm can be judged by lighting up with 1.5V battery directly, but 940nm can be judged by using mobile phone or camera;
6. Under the same current condition, because the voltage of 940nm is lower, the power consumption of 940nm is smaller than that of 850nm, so the current of 940nm with the same size can be larger than that of 850nm;
7. The service life of 850nm is longer than that of 940nm.
⭐Application of 850nm and 940nm
1. Band 850nm (security, infrared night vision monitoring, infrared camera, infrared supplementary light)
When using 850nm emission tube, it is necessary to pay attention to anti-static. The soldering iron should not exceed 30W, the time should not exceed three seconds, the temperature should not exceed 260 ℃ and the time should not exceed three seconds.
2. Band 940nm (remote control, face recognition, detection sensor)
Infrared wavelength commonly used are: 820nm, medical. 850nm, in terms of security, 870nm is used in highway detection, 940nm in remote control.
⭐How to know if the IR light work normally
1. With digital multimeter on both feet, there should be a change of zero or a few volts in the sun and in the dark;
2. The positive pole is connected to the forward power supply of 3V. Turn on the power supply to the radio. The sound of the radio indicates that the infrared diode is good;
3. Connect a 1K resistor in series with the infrared transmitting tube, connect it with 3V power, and use the camera function of mobile phone to see if there is white light;
4.Check directly with the mobile phone camera, normal work is in the mobile phone camera is able to see the red light.