Safety device including safety circuit that resumes supply of relay operation voltage, when predetermined cancellation is executed, and image forming apparatus

A safety device comprising:

• a load that operates with power supplied thereto;
• a relay circuit that turns on power to the load, when a predetermined relay operation voltage is supplied, and turns off the power to the load, when the relay operation voltage is not supplied;
• a first operation voltage line for supplying the relay operation voltage to the relay circuit;
• an emergency stop switch;
• a safety circuit connected to the relay circuit via the first operation voltage line, to control supply status of the relay operation voltage to the relay circuit, and configured to shut off the power supply when a stop signal is inputted from the emergency stop switch, thereby disconnecting the supply of the relay operation voltage to the relay circuit through the first operation voltage line;
• an abnormality detector that outputs an abnormality signal indicating abnormality of the load, upon detecting the abnormality of the load;
• a second operation voltage line for supplying the relay operation voltage to the safety circuit;
• a drive power line connected to the second operation voltage line, to supply drive power to the safety circuit;
• a disconnection circuit connected to a power source that supplies the relay operation voltage and the drive power, and to the second operation voltage line, and configured to control electrical continuity of the second operation voltage line;
• and
• a controller that includes a processor, and controls operation of the disconnection circuit, when the processor executes a control program,
• wherein the disconnection circuit is configured to:
• disconnect the second operation voltage line, thereby disconnecting the supply of the drive power and the relay operation voltage from the power source, when the abnormality signal is inputted from the abnormality detector, with the relay operation voltage and the drive power being supplied to the safety circuit through the second operation voltage line and the drive power line;
• and
• resume the supply of the drive power and the relay operation voltage to the safety circuit, by making the second operation voltage line electrically continuous, when the abnormality signal ceases to be inputted from the abnormality detector, with the supply of the relay operation voltage and the drive power being suspended, and
• the safety circuit resumes, upon executing a predetermined cancelling operation, with the supply of the drive power and the relay operation voltage to the safety circuit having been resumed, the supply of the relay operation voltage to the relay circuit through the first operation voltage line.