| 摘要 |
PROBLEM TO BE SOLVED: To always monitor appropriate off-set voltage, with a simple configuration without mounting a timer function.SOLUTION: An off-set determination unit 120A determines a threshold Von the basis of a volume specification value VLS transmitted from a volume specification unit 400. A detection unit 110A performs detection of detection voltage values VD, VDof output signals S, Sfrom a power amplifier 320, detection of magnitude relation between the detection voltage values VD, VDand a reference value, and detection of the detection voltage values VD, VDhaving exceeded the threshold V. Subsequently, a counting unit of the off-set determination unit 120A individually counts, in periods until the detection voltage values VD, VDhave been equal to or lower than the reference value after the detection voltage values have exceeded the reference value, the number of times when the detection voltage value VDhas exceeded the threshold Vand the number of times when the detection voltage value VDhas exceeded the threshold V. A determination unit of the off-set determination unit 120A determines, on the basis of a result of the counting by the counting unit, whether or not an off-set voltage abnormality has occurred.SELECTED DRAWING: Figure 1 |
