| 摘要 |
PROBLEM TO BE SOLVED: To realize preventive maintenance of a keyboard by determining in advance a condition unable to transmit key code data caused by a key switch trouble. SOLUTION: Key switch conditions on a key matrix (3) are detected for every scanning output signal (2) transmitted from a microprocessor (1). A sense signal (4) is reversed and transmitted to the microprocessor (1) at the key input. The key code data is transmitted to a host computer (8). In this case, after amplifying decreased voltage caused by contact resistance of the key switch generating on the sense signal (4) by an amplifier (5), the output to the microprocessor (1) is reversed when comparing with reference voltage set up with a comparator (6) by assuming a replacement period and detecting a value exceeding the reference voltage, and the microprocessor (1) reports it to the host computer (8). COPYRIGHT: (C)2007,JPO&INPIT
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