KEY DEPRESS DETECTING CIRCUIT AND RADIO TERMINAL

摘要

PROBLEM TO BE SOLVED: To provide a key depress detecting circuit that radiation noises caused by key depress detection can be remarkably reduced, keying can be immediately detected without deteriorating sensitivities and the detection is enabled with low power consumption. SOLUTION: This detecting circuit is provided with potential setting means 1, 2 and 3 for applying a prescribed potential level to all the column contacts of a key contact 4, keying detecting means 5, 6 and 1 for detecting keying, when the potential of any column contact becomes a pressing level based on the said potential level and deciding means 1, 2, 3, 5 and 7 for deciding the closed key contact by successively applying the prescribed potential level for each column unit of the column contacts and detecting the pressing level corresponding to the potential level for each row unit of row contacts, when the depressing of key contact is detected by the key depress detecting means.