PURPOSE: To shorten a processing time required for a key scan processing by preventing the key scan from being successively operated to entire SCAN lines when the ON/OFF state of each key contact is not changed even when a key being always in the ON state such as a dummy key is present thereon.
CONSTITUTION: This method is constituted of a first scan processing 81 which detects in a batch the presence or absence of the key contact ON only of the SCAN line whose key contact ON is not detected at the previous time, a second scan processing 83 which successively detects the presence or absence of the key contact ON of each SCAN line which is not the object of the detection of the presence or absence of the key contact ON by the first scan processing 81, when the key contact ON of any SENSE line is not detected as the result of the first scan processing 81, and a third scan processing 84 which successively detects the presence or absence of the key contact of the entire SCAN lines when the key contact ON of any SENSE line is detected as the result of the first scan processing 81.
IKEGAMI YASUO
NOMURA YOSHIAKI
HITACHI VIDEO & INF SYST