Conventional infrared LED lamp beads are similar in appearance to general visible light LED lamp beads, but they emit infrared rays. The voltage is generally about 1.4v, and the working current is generally less than 20mA. In order to adapt to different operating voltages, current-limiting resistors are often connected in the loop.
When using infrared LED lamp beads to control the corresponding controlled device, the distance controlled by it is proportional to the transmitting power. In order to increase the control distance of infrared rays, the infrared emission tube works in a pulsed state, because the effective transmission distance of pulsating light is proportional to the pulsed wind-induced current, and the emission distance of infrared light can be increased by increasing the peak value Ip as much as possible. The method to increase Ip is to reduce the pulse duty ratio, that is, compress the pulse width T, reducing the pulse duty ratio can also greatly increase the emission distance of the low-power infrared light-emitting diode. The power of ordinary infrared light-emitting diodes is divided into three categories: low power, medium power and high power. To make infrared light-emitting diodes produce modulated light, only a certain frequency pulse voltage is applied to the drive tube.
When the infrared light-emitting diode emits infrared rays to control the controlled device, there are corresponding infrared photoelectric conversion elements in the controlled device, such as infrared receiving diode, infrared receiving head, photosensitive triode, etc.
There are two ways to transmit and receive infrared rays: direct and reflective. Direct type means that the luminous tube and the receiving tube are placed at the opposite ends of the transmitter and the controlled object, with a certain distance between the middle; the reflective type means that the luminous tube and the receiving tube are arranged side by side, the receiving tube is always without light, and only the infrared light emitted by the luminous tube When the light meets the reflector, the receiving tube will only work after receiving the reflected infrared light. The dual-tube infrared emission circuit can increase the emission power and increase the range of infrared emission.
According to the characteristics of infrared LED lamp beads, it can be more widely used according to different wavelengths:
1. Wavelength: 808nm, suitable for pump light sources of medical appliances, space optical communications, infrared lighting, and solid-state lasers;
2. Wavelength: 830nm, suitable for automatic card swiping system on highways (night vision system is best, you can see a little red light on the die, the effect is better than 850nm);
3, Wavelength: 840nm, suitable for cameras, color zoom infrared waterproof;
4. Wavelength: 850nm, suitable for cameras, digital photography, monitoring, building intercom, anti-theft alarm, infrared waterproof;
5. Wavelength: 870nm, suitable for cameras in shopping malls and intersections;
6. Wavelength: 940nm, suitable for remote control, such as remote control for household appliances.
