KEYBOARD CIRCUIT, AND DETECTING METHOD FOR THE SAME

PROBLEM TO BE SOLVED: To enable the number of wires for a substrate for keyboard switches to be so significantly reduced that only one face of the substrate would be sufficient for the wiring.SOLUTION: A Key block 71 detects the on/off states of a plurality of contacts in a format conforming to input/output signals of a two-dimensional switch matrix. A Keyplus block 72 detects the on/off states of a plurality of contacts in a format conforming to input/output signals of a three-dimensional switch matrix, converts result of detection into the format conforming to input/output signals of the two-dimensional switch matrix, and inputs or outputs to or from the Key block 71. Selectors S0 to S4, when the two-dimensional switch matrix is used, so changes over the wiring as to connect the two-dimensional switch matrix and the Key block 71 or, when the three-dimensional switch matrix is used, so changes over the wiring as to connect the three-dimensional switch matrix, the Keyplus block 72 and the Key block 71.