1, mechanical keyboard.

Advantages: durable, good feel.

Disadvantages: Not waterproof.

Mechanical keyboard, generally similar to the principle of metal contact switch, makes the contacts on or off. In practical application, there are many structural forms of mechanical heads, and the most commonly used one is cross contact. Striking is laborious, typing is fast and it is easy to miss words. But now better mechanical keyboards have added the click function. In fact, the click function is improved from the mechanical structure, and the cache is added to prevent missing words when typing quickly. Its service life is about 50 million to 1 100 million times, and the average user hits the keyboard about 200,000 times in 10 years.

2, plastic film keyboard.

Advantages: cheap and waterproof;

Disadvantages: poor feel and short life.

The plastic film keyboard has four layers. One layer of plastic film has raised conductive rubber, one of which is an isolation layer, and the upper and lower layers have contacts. Press the rubber bump through the key to make the upper and lower layers of contacts contact and output the code. This keyboard has no mechanical wear and high reliability.

3. Conductive rubber keyboard.

The contact of conductive rubber keyboard contacts is made of conductive rubber. Its structure is a layer of conductive rubber with bumps, the bumps are conductive, this part is for each key, and the interconnected plane parts are non-conductive. When the key cap is pressed, the lower contact is pressed because the bump is conductive. If it is not timely, the bump will bounce. At present, it is also used more. ,

4. Capacitive keyboard.

Capacitive keyboard, similar to the principle of capacitive switch, changes the capacitance by pressing the key to change the distance between electrodes, and temporarily forms the condition that allows the impact pulse to pass. As we know, the capacitance of a capacitor is determined by the medium, the distance between the two poles and the area of the two poles. Therefore, when the key cap is pressed, the distance between the two poles changes, resulting in a change in capacitance. The parameters are designed properly, and there is output when the key is pressed, and there is no output when the key is not pressed. The output is shaped and amplified to drive the encoder. Because the capacitor has no contact, there are no problems such as wear and poor contact in the working process, and the durability, sensitivity and stability are good. In order to prevent dust from entering between the electrodes, the capacitive key switch is sealed and assembled. 100000 to 30 million lives. But at present, there are not many real capacitive keyboards on the market, most of them are the first two kinds of keyboards, and a real capacitive keyboard is more expensive.

5. Wireless keyboard.

Advantages: no need for cable connection;

Disadvantages: batteries are needed and consumed, and the cost is very high.

There is no direct physical connection between the keyboard and the computer, and the input information is transmitted to a special receiver by infrared rays or radio waves. The connection of the receiver is basically the same as that of the ordinary keyboard, just connect PS/2 or COM port, USB port, etc. And be sure to pay attention to the difference when buying. Wireless keyboards generally have the suffix "RF" after the logo, indicating that they support radio wave transmission. At present, the frequencies of most products are around 900 MHz, 455 MHz and 330MHz.