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Remote control works
2015-04-02 15:15:53 From:Localhost Font-size:TTT
[Description]Many appliances are using an infrared remote control, infrared remote control works then what is it? First, we l
Many appliances are using an infrared remote control, infrared remote control works then what is it? First, we look at what is infrared.The human eye can see by the wavelength of visible light from long to short order, followed by red, orange, yellow, green, cyan, blue, purple. Wherein the red light wavelength range of 0.62 ~ 0.76μm; violet wavelength range of 0.38 ~ 0.46μm. Shorter wavelength than violet is called ultraviolet light, longer wavelength than red light called infrared.
Infrared remote control signal is transmitted using a wavelength of near infrared between 0.76 ~ 1.5μm.
Commonly used infrared remote control transmitter and receiver system is generally divided into two parts.
The main element is an infrared-emitting portion of a light emitting diode. It is actually a special light emitting diode, because of its internal material different from the ordinary light emitting diodes, so when a certain voltage is applied to both ends thereof, it will be issued instead of visible light is infrared.
Infrared wavelengths of infrared light-emitting diode emits currently widely used is about 940nm, shape and general five-emitting diode same, just different colors.
Infrared light-emitting diodes are generally black, dark blue, transparent three colors.
Infrared light-emitting diode is good or bad judgment and judgment ordinary diode same way: with a multimeter power block look at the amount of infrared light-emitting diodes, the reverse resistor.
Luminous efficiency of infrared light-emitting diodes use special equipment to accurately determine, but can only be used under the conditions to pull away from an amateur to a rough determination method. Infrared receiving portion receiving tube is a photodiode.
Give infrared receiver diode is reverse biased, it can work in practice normal, i.e. infrared receiver diode in the circuit when the application is to use the reverse, in order to get higher sensitivity.
Infrared receiver diodes are generally circular and square.
Since the transmission power of the infrared light emitting diode generally small (about 100mW), so the infrared receiving diode of the received signal is relatively weak, and therefore necessary to increase the high-gain amplifier circuit.
A few years ago used μPC1373H, CX20106A and other special infrared receiver amplifier. In recent years, whether formal or amateur production of products, most of them are finished using infrared receiver.
Finished infrared receiver packages are basically two types: one using metal shield; a plastic package. Have three pins, power supply positive (VDD), the power of negative (GND) and data output (VO or OUT). Infrared receiver pinout vary due to different models, refer to the manufacturer's instructions. Advantages finished infrared receiver is that no complex debugging and shielded enclosure, to use as a transistor, very convenient. But pay attention to the finished product when using infrared receiver carrier frequency.
Infrared remote control commonly used carrier frequency 38kHz, 455kHz oscillator which is used by the transmitter to decide.
On the transmit side want to make crystal integer division, the division factor 12 general admission, so 455kHz ÷ 12≈37.9 kHz≈38kHz. There are also some remote system using 36kHz, 40kHz, 56kHz, etc., usually by the oscillation frequency of the transmitter oscillator to decide.
Features infrared remote control does not affect the surrounding environment, do not interfere with other electrical equipment. Because it can not penetrate walls, it can be used in different rooms of household appliances universal remote control without causing mutual interference; circuit debugging as simple as pressing a given circuit connection is correct, usually without any debugging can be put to work; codecs easy, multi-channel remote control.
As a result of the production of a large number of manufacturers of infrared remote control ASIC, you need to find what you want. Accordingly, infrared remote control is now in household appliances, indoor short distance (less than 10 m) of the remote control has been widely applied.
Infrared-emitting portion of the infrared remote control multiplexer multiplexing control system typically has many buttons, representing different control functions. When the transmitter is pressed a button, respectively at the receiving end have different output states.
The output state of the receiver can be divided into pulses, level, self-locking, interlocking, five forms of data. "Pulse" output when you press the transmitter button, the corresponding output of the receiver outputs an "effective pulse", width is generally around 100ms. "Level" refers to the output of the transmitter button is pressed, the receiver output terminals corresponding "effective level", release the button when the transmitter, the receiver "effective level" disappear. By "effective pulse" and the "effective level" may be high, it may be low, depending on the status of the corresponding output pin is static, such as static low, the "high" is effective; static high as , the "low" as valid. In most cases, "high" as valid. "Self-locking" refers to the transmitter output every time you press a key, the receiver corresponds to the output changes state, ie the original high to low, the original low to high. Such output is suitable as a power switch, mute control. This is sometimes known as the output format as "inverted." "Interlock" output refers to multiple output clear each other at the same time there is only one output is active. TV channel selection in the case of such a case, other issues such as dimming, speed, audio input selection.
"Data" refers to the number of transmit output key is assigned a number, use the receiving end of several output form a binary number to represent different key input.
Under normal circumstances, the receiving end in addition to several output data, there should be a "data valid" output to the subsequent stage in a timely manner to take data. This output format is generally used with a microcontroller or computer interface. In addition to the above output format, as well as "latch" and "Scratch" two forms. The so-called "latch" signal output means for transmitting end of each hair, the corresponding output of the receiver to be "stored" until it receives a signal so far; "Scratch" outputs "level" the introduction of similar output.