Patent ID: 7495657

Claim:
A keyboard comprising: a key module comprising a plurality of key cells each having an output end being selectively connected to one of a first voltage while being pressed and a second voltage while not being pressed; a detect circuit electrically connected to the outputs end of the key cells for generating a control signal whenever one of the output end of the key cell becomes connected to the other of the second voltage and the first voltage, wherein the detect circuit comprises an amplifying circuit and a plurality of capacitors each having a first end being coupled to the output end of each of the key cells, respectively, and having a second end; a parallel-to-serial register electrically connected to the output end of the key module; and a processor electrically connected to the parallel-to-serial register and the detect circuit for controlling the parallel-to-serial register according to the control signal without polling for a status of the key cells during a time period between any key cell being connected to the first voltage and then connected to the second voltage; wherein the second ends of the capacitors are connected together and coupled to the amplifying circuit, and the amplifying circuit is configured for amplifying a voltage in one of the capacitors and has an output end for outputting the amplified voltage; and wherein the control signal is generated according to the amplified voltage.