Foot controller connection error detection device for sewing machines

A foot controller contact failure detection device of a sewing machine comprising:

• a foot controller to output a start/stop instruction and rotation speed instruct to a control unit to control a sewing machine motor;
• a plug to disconnectably connect the foot controller to the control unit having a microcomputer;
• a variable resistor connected in between a power line and an earth line inside the foot controller, in which a resistance value changes in correspondence with an amount of depression of the foot controller;
• a diode connected in between the power line and the earth line in a reverse direction to a power applying direction and connected in parallel with the variable resistor;
• and
• a constant voltage applier to apply constant voltage to the earth line via a resistance having a resistance value smaller than the resistance value of electricity paths including the variable resistor and the microcomputer is arranged so that a scale of potential between the power line and the earth line can be set so that the contact failure of the connector in between the plug and the control unit is detected based on the voltage of the earth line set such that the voltage applied by the constant voltage applier becomes a forward voltage to the diode.

A foot controller connection error detection device of a sewing machine comprising:

• a foot controller to output a start/stop instruction and rotation speed instruction to a control unit to control a sewing machine motor;
• a plug to disconnectably connect the foot controller to the control unit having a microcomputer;
• a variable resistor connected in between a power line and an earth line inside the foot controller, in which the resistance value changes in correspondence with the amount of depression of the foot controller;
• a diode connected in between the power line and the earth line in a reverse direction to a power applying direction and connected in parallel with the variable resistor;
• wherein the power line is connected to a first output port and a second output port of the microcomputer;
• and
• the microcomputer switches between a normal operation mode to apply a constant voltage to the power line from the first output port via a first resistance having a predetermined resistance value, and a connection error detection mode to apply constant voltage to the power line from the second output port via a second resistance having a smaller resistance value than the resistance value of electricity paths including the variable resistor,
• in which the connection error detection mode detects the contact failure in a connector of the plug based on the voltage of the connection point of the second resistance and the power line.