| 摘要 |
PROBLEM TO BE SOLVED: To provide a load drive circuit capable of elongating life of a mechanical relay, in the load drive circuit using both the mechanical relay and a semiconductor element.SOLUTION: In a load drive device, a relay contact point 3a of a mechanical relay 3 is arranged in series to an evaporation heater 1, and a semiconductor element 4 performing switching operation is arranged in parallel to the relay contact point 3a. In the load drive device, at an opening/closing operation of the mechanical relay 3, a microcomputer 5 makes the semiconductor element 4 perform an on operation for a predetermined time period including at the operation time. When outputting an operation command instructing of opening/closing switching of the mechanical relay 3, the microcomputer 5 performs control so that an output timing of the operation command is distributed to a positive side time period and a negative side time period in an AC waveform of an AC power supply 2 by using a zero-cross monitoring signal having a cycle equivalent to that of a zero-cross of the AC power supply 2 as a reference. |
