Patent ID: 8248276

Claim:
A scanning circuit for a keyboard with a plurality of keys, the scanning circuit comprising: n rows L 1 ˜Ln, wherein n is a natural number not less than two; and 2n columns P 1 - 1 ˜P 1 - n and P 2 - 1 ˜P 2 - n; wherein the n rows L 1 ˜Ln and the n columns P 1 - 1 ˜P 1 - n cooperatively form a switch matrix comprising n*n switches S 1 - 1 ˜Sn-n, all ends of the switches in the same row electrically connected to one of n I/O ports K 1 ˜Kn, respectively, the ends of the switches in the same column electrically connected to ground via one resistor R 1 - 1 ˜R 1 - n , respectively, each of resistors R 2 - 1 ˜R 2 - n is electronically connected in one column of the columns P 2 - 1 ˜P 2 - n , and connected between one of the I/O ports K 1 ˜Kn and ground via one of the resistors R 1 - 1 ˜R 1 - n , respectively.