Non-contact power supply device

A non-contact power supply device in which a primary unit and a secondary unit of a coupling transformer are separated for use and transfers electric power from the primary unit to the secondary unit through electromagnetic induction in a non-contact fashion, wherein:

• said secondary unit of the coupling transformer comprising:
• a second rectifying smoothing circuit for rectifying and smoothing a high frequency alternating current flowing through a secondary winding based on a high frequency alternating current flowing through a primary winding of the primary unit in order to produce a DC (direct current) output voltage;
• a voltage hold circuit for maintaining the DC output voltage from the second rectifying smoothing circuit for a predetermined time length;
• a constant voltage output circuit for producing a constant voltage based on the DC output voltage from the voltage hold circuit;
• a control circuit provided with the constant voltage from the constant voltage output circuit as a power source for controlling an operation of a load connected to said secondary unit;
• and
• a drive signal generation circuit for supplying a drive signal to the control circuit when the output voltage from the second rectifying smoothing circuit becomes smaller than a predetermined voltage;
• and said primary unit of the coupling transformer comprising:
• an operation circuit for either stopping the high frequency alternating current flowing through the primary winding or changing the frequency of the high frequency alternating current flowing through the primary winding to decrease the DC output voltage of the second rectifying smoothing circuit smaller than said predetermined voltage for generating said drive signal by said drive signal generation circuit.