E-Field Touch Keyboard

Keyboard is one of the most important input devices of the personal computer (PC). It consists of set of keys arranged in matrix form interfaced with microcontroller to transmit proper key-press signal to the PC. Mechanical type of keyboards are most popular and in use since the inception of computers. Among mechanical type keyboards, rubber dome, metal contact and foam element types are most common. An alternate of mechanical types, which is in use, are capacitive type non-mechanical.

E-Field Touch Keyboard is an effort to replace present keyboard having mechanical type switches with a "Touch keyboard". It reduces the strain on finger muscles and chances of related diseases. The probability of a key not working is also very less as by no means dust and dirt can enter into it to interrupt the key's function. The Basic idea regarding hardware design is to place two thin and small electrodes of triangular shape below the sheet marked with keyboard letters. The electrodes connected together to form a matrix of 9 columns and 4 rows. It will sense the presence of finger near it and send the signal to the E-Field sensor board, the MCU on which will further decode and identify the key and send it to PC either as PS/2 compatible signal or Serial signal. As there are only 9 electrodes available on the E-Field sensor so the keyboard is divided into group of nine keys and signal to/from electrodes are multiplexed using Analog multiplexer with very low capacitance and very high speed. Freely available COM File Software is used in this project to read the keypress. Later it can be implemented for PS/2 or serial keyboard interface to PC and will be used in replacement of Mechanical type keyboards. For the sake of simplicity and at the same time demonstrating the project idea, touch keyboard with 36 keys is implemented. As a future implementation this can be extended to replace the complete 104 key windows keyboard with E-Field touch keyboard.