Patent ID: 8564460

Claim:
A keyboard device including a keyboard comprising: multiple key switches respectively disposed at junctions between multiple scan lines and multiple detection lines; a scan memory to temporarily store a result obtained by scanning the keyboard as scan data; a confirmed data memory to store a confirmed key input; and a control unit configured to read out scan data from the scan memory and, for each particular key switch indicated by the scan data read out from the scan memory to be in an on-state, determine whether or not at least one other key switch disposed on a particular scan line on which the particular key switch is disposed is also indicated by the scan data to be in an on-state, wherein in a case that the control unit determines that no other key on the particular scan line on which the particular key switch is disposed is in an on-state, the control unit outputs a key code corresponding to the particular key switch, and wherein the control unit compares the scan data of the particular scan line and scan data of a preceding scan line immediately preceding the particular scan line and determines whether or not an adjacent key switch, disposed on the preceding scan line that is immediately preceding the particular scan line and disposed on a same detection line on which the particular switch is disposed is in an on state and in a case that the control unit determines that at least one other key on the particular scan line on which the particular key switch is disposed is in an on-state and the control unit determines that the adjacent key switch on the preceding scan line and on the same detection line on which the particular key switch is disposed is not in an on state, the control unit outputs code corresponding to the particular key switch, wherein in a case that the control unit determines that at least one other key on the particular scan line on which the particular key switch is disposed is in an on-state and the control unit determines that the adjacent key switch on the preceding scan line and on the same detection line on which the particular key switch is disposed is in an on-state, the control unit determines that the on-state of the particular key switch is dummy input caused by sneak current, and the control unit outputs an error code, and deletes the data for the particular scan line from the confirmed data memory, and wherein when the control unit determines that three key switches, constituted by (i) the particular key switch, (ii) the one other key on the particular scan line on which the particular key switch is disposed, and (iii) the adjacent key switch on the preceding scan line and on the same detection line on which the particular key switch is disposed, are in the on-state at the same time, the control unit outputs the error code and without outputting a key code for any of said three key switches.