Keyboard PCB

Keyboard PCB is a circuit board in a computer or device keyboard, which is designed to sense when a key is pressed, determine what key is pressed, and send information to a computer or other device connected to the keyboard. The keyboard circuit board consists of two main parts. When the key is pressed, the keyboard circuit is either completed or disconnected, telling the keyboard PCB controller the position of the key. There is also a microprocessor on the keyboard PCB, called the keyboard controller, Some read-only memory (ROM) is used to store information about which key positions are equivalent to which characters and some hardware interfaces are used to send key data to another device, such as universal serial bus (USB) or serial port connector. The material for making keyboard PCB is FR4 PCB material or FPC Flexible PCB.

There are two main methods to capture keys on the keyboard printed circuit board.

The first method is to place a small PCB conductive board at the bottom of the key. When the key is pressed, the keyboard printed circuit board connects the circuit on the circuit board and sends a signal to the controller to inform the keyboard controller of the position of the key. Then, the keyboard controller can use a table stored in the keyboard ROM to determine the characters of the position

The second is the keyboard circuit board covered in the active and complete circuit. Sometimes called a capacitive keyboard, electrical signals constantly pass-through this keyboard PCB. There is a small board at the bottom of each key. When the key is pressed, it is close enough to the circuit array to change the charge through the following circuit. This current change is detected by the keyboard controller to determine which key was pressed.

Keyboard Classification by code

Full coding keyboard

Because the keyboard is arranged by the key matrix switch, each key will be generated by the single-chip microcomputer inside the keyboard through the decoder. The whole process of coding information depends on the keyboard's own hardware and only transmits the coding information to the computer.

Non-coding keyboard

The keyboard circuit hardware is driven by corresponding software, and the corresponding keyboard processing programs (query program, transmission program, and decoding program) are used for scanning, coding, and transmission.

Keyboard handler procedure:

1.The main program calls the query program, scans the key position matrix line by line through the query interface, detects the output of rows and columns, determines the coordinates of a closed key from the intersection signal of rows and columns, and obtains the scanning code corresponding to the key.

2.The main program calls the transfer program to transfer the obtained scanning code to the keyboard interface circuit located in the host.

3.The main program calls the decoding program to translate the scanning code in the keyboard interface into the coding information of the corresponding key.

4.When necessary, the keyboard interface circuit transmits the above encoded information to the host.

Full code keyboard has fast response speed and no key position conflict, but it costs a complex hardware structure, and its complexity increases with the increase of key function. Now it has been rarely used.

The response speed of noncoding keyboard is not as fast as that of the full coding keyboard, and there is a problem of key position conflict, but it can redefine some keys of the keyboard through software, which provides great convenience for expanding the keyboard function. Therefore, it is widely used.

Classification according to interface connection mode, PS2 (round head), USB, Wireless (receiver or Bluetooth).

Keyboard

What kind of keyboard do you know? Which keyboard would you prefer?

I don't know that there are many kinds of keyboards. Think about how many people haven't touched their desktops after they have a laptop. Of course, gamers are another matter. The keyboard is divided into the mechanical keyboard, membrane keyboard, and capacitive keyboard. It seems that there is no need to listen to the name alone.

We can't understand the difference. Here's a simple popularization.

Each key of the mechanical keyboard is a separate switch, also known as the mechanical axis, so some game players will choose the mechanical keyboard by selecting the axis body; Mechanical keyboard adopts a metal contact switch, and its working principle is to make the contact on or off. It is characterized by a simple process, high noise, easy maintenance, strong rhythm during typing, and the hand feeling will not change after long-term use. A mechanical keyboard is the best choice for playing games.

Mechanical keyboard

The essential difference in architecture between the membrane keyboard and the mechanical keyboard leads to different trigger principles. In short, the mechanical keyboard is knocked down and the membrane keyboard is pressed down, so the natural feel is different. The two are also very different in price. The knot of a mechanical keyboard. The structure is precise and the process is difficult, so it is more expensive than the film keyboard. The plastic film keyboard is divided into four layers without mechanical wear. It is characterized by low noise and low cost, but its long-term use will change the feel due to material problems. Change. However, it still occupies most of the market share due to its durability and low price. The difference between it and the mechanical keyboard is that the trigger principle and pressing feel are different. The trigger unit of the mechanical keyboard is the shaft, and the membrane keyboard depends on the membrane.

Membrane keyboard

Capacitive keyboards are even more rare and expensive. The keyboard uses the change of capacitance to open and close the keys, which can be knocked without physical contact points. Therefore, it has a very light hand feeling, sensitive response, no wear, and good sealing. At present, there are only the Japanese is doing it. The contact structure of the conductive rubber keyboard is connected through conductive rubber. There is a layer of convex charged conductive rubber inside the keyboard, and each key corresponds to a convex when pressed. Will connect the following contacts. This kind of keyboard is a transitional product from mechanical keyboard to membrane keyboard, which is rarely seen in the market.

Contactless electrostatic capacitance keyboard is nicknamed "the emperor of the keyboard". It uses the principle of the capacitive switch and uses the key to change the distance between electrodes to cause the change of capacitance, so as to drive the encoder to open and close the key, which can be realized without physical contact points. Now knock. It is characterized by a very light hand feel, sensitive response, no wear, and good sealing. Capacitive keyboards are less common and more expensive than other types.

Mechanical keyboard means that the key trigger is metal and metal, and there is a separate microswitch and printed circuit board under each key of the mechanical keyboard, which makes typing feel better. A good mechanical keyboard and partition pressure design are very suitable for people who input text for a long time, which can reduce fatigue, and it is not easy to have key position conflict in the game.

Compared with membrane keyboard, the mechanical keyboard has the following advantages:

1. The service life of a mechanical keyboard is higher than that of an ordinary membrane keyboard. A good mechanical keyboard has a service life of more than 10 years or even 20 years, and the single key can be hit twice. Up to 50 million times.

2. After the mechanical keyboard has been used for a long time, the feel of the keys will not change, but the film can not be achieved.

3. The key feel of different axes of the mechanical keyboard is different, and the touch of the film is single.

4. Mechanical keyboard can achieve 6 keys without conflict, good machinery can have full keys without conflict, while the film is generally 3 keys without conflict.

5. You can change the keycap yourself, which is convenient for personalized DIY.

Keyboard PCB needs a professional PCB manufacturer, and iPCB provides prototype production of printed circuit board.