Infrared remote control (IR Remote Control) is a remote control device that uses near-infrared rays with a wavelength between 0.76 and 1.5 μm to transmit control signals.
Commonly used infrared remote control systems are generally divided into two parts: transmitting and receiving.
(1) The main components of the emitting part are infrared light-emitting diodes. It is actually a special light-emitting diode. Because its internal material is different from ordinary light-emitting diodes, when a certain voltage is applied to its two ends, it emits infrared rays instead of visible light.
Infrared light emitting diodes that are widely used have an infrared wavelength of about 940nm, and the shape is the same as ordinary light emitting diodes, but the color is different.
(2) The main component of the receiving part is an infrared receiving diode, which is generally round and square. In practical applications, the infrared receiving diode needs to be reverse biased so that it can work normally, that is, the infrared receiving diode is used in the reverse direction when used in the circuit, so that higher sensitivity can be obtained.
Since the emission power of infrared light-emitting diodes is generally small (about 100mW), the signal received by the infrared receiving diode is relatively weak, so a high-gain amplifier circuit must be added. In recent years, most of the finished infrared receiving heads have been used.
There are roughly two types of packages for the finished infrared receiver: one is shielded by iron sheet; the other is plastic package. There are three pins, namely power supply positive (VDD), power supply negative (GND) and data output (VOUT). The pin arrangement of the infrared receiver varies from model to model, please refer to the manufacturer's instructions. The advantage of the finished infrared receiver is that it does not require complicated debugging and shell shielding, and it is very convenient to use like a triode. But pay attention to the carrier frequency of the finished infrared receiver when using it.
The commonly used carrier frequency for infrared remote control is 38kHz, which is determined by the 455kHz crystal oscillator used by the transmitter. At the transmitting end, the crystal oscillator should be divided by integer frequency, and the frequency division coefficient is generally 12, so 455kHz÷12≈37.9kHz≈38kHz. There are also some remote control systems that use 36kHz, 40kHz, 56kHz, etc., which are generally determined by the oscillation frequency of the crystal oscillator at the transmitter.
The characteristic of infrared remote control is that it does not affect the surrounding environment or interfere with other electrical equipment. Because it cannot penetrate the wall, household appliances in different rooms can use a universal remote control without mutual interference; circuit debugging is simple, as long as the given circuit is connected correctly, generally it can be put into operation without any debugging; codec Easy, multi-channel remote control is possible. Therefore, infrared remote control has been widely used in household appliances and indoor remote (less than 10 meters) remote control.
