Power supply apparatus for the reduction of power consumption

Abstract

A power supply apparatus having an AC power supply, a transformer, a switching element and a control circuit for controlling an operation of the switching element: where an electrical current is supplied to the primary side of the transformer intermittently when a main unit of an electrical appliance to which the power supply apparatus is applied is in a standby mode so that unnecessary power consumption is reduced. Further, a capacitance is provided between the AC power supply and the control circuit instead of the conventional initializing resistance and the control circuit is driven using an electrical current going through a reactance component of the capacitor, so that the energy loss is not caused any more by the initializing resistance.

What is claimed is:  
     
         1 . A power supply apparatus comprising an AC power supply a transformer, a switching element for relaying an electrical current supplied into said transformer, and a control circuit for controlling an operation of said switching means, wherein said control circuit is provided at a primary side of the transformer and said control circuit controls an operation of said switching element so that the electrical current is supplied into a primary coil of said transformer intermittently.  
     
     
         2 . A power supply apparatus according to  claim 1 , wherein a capacitor is provided between said AC power supply and said control circuit and said control circuit is driven by using an electrical current going through a reactance component of said capacitor.  
     
     
         3 . A power supply apparatus according to  claim 1  or  2 , wherein said control circuit is driven in response to a signal give from an outside to conduct said operation of the switching element intermittently.  
     
     
         4 . A power supply apparatus according to  claim 1  or  2  further comprising a load current detecting means for detecting a load current of said power supply apparatus, wherein said control circuit is driven in response to the load current detected by the load current detecting means.  
     
     
         5 . A power supply apparatus according to  claim 1  or  2  further comprising a duty cycle detecting means for detecting a duty cycle of said switching element, wherein said control circuit is driven in response to the duty cycle of the switching element detected by the duty cycle detecting means.  
     
     
         6 . A power supply apparatus according to  claim 1  or  2  further comprising a monitoring means for detecting a oscillating frequency of an oscillator for driving said switching element, wherein said switching operation of said switching element is conducted intermittently by stopping said oscillation in said oscillator in response to an output of said detecting means.  
     
     
         7 . A power supply apparatus according to any one of  claims 4  to  6 , wherein said load current, said duty cycle, or said oscillating frequency is detected with the aid of a comparator.  
     
     
         8 . A power supply apparatus according to any one of  claims 4  to  6 , wherein said load current, said duty cycle, or said oscillating frequency is detected with the aid of a comparator having a hysteresis characteristic.  
     
     
         9 . A power supply apparatus according to any one of  claims 4  to  6 , wherein said load current, said duty cycle, or said oscillating frequency is detected with the aid of a comparator and a time delay element.  
     
     
         10 . A power supply apparatus according to any one of  claims 1  to  9 , wherein a forward circuit and a flyback circuit are provided at a secondary side of said transformer in parallel.  
     
     
         11 . A power supply apparatus according to any one of  claims 3  to  10 , wherein said signal detecting means for detecting a signal given from an outside, said load current detecting means, said duty cycle detecting means or said oscillating frequency monitoring means is arranged at a secondary side of said transformer, and the signal detected by these means is transferred to a primary side of said transformer by using a third coil provided on said transformer or by another transformer, or a photo coupler.  
     
     
         12 . A power supply apparatus comprising an AC power supply, a transformer, a switching means for switching an electrical current supply line for supplying electrical current to said transformer, a control circuit for controlling an operation of said switching means, wherein said control circuit is provided at a primary side of the transformer and said control circuit controls an operation of said switching means so that the electrical current is supplied into a primary coil of said transformer intermittently.  
     
     
         13 . A power supply apparatus according to  claim 12 , wherein a capacitor is provided between said AC power supply and said control circuit; wherein said control circuit is driven by using an electrical current going through a reactance component of said capacitor.  
     
     
         14 . A power supply apparatus according to  claim 12  or  13 , wherein said control circuit is driven in response to a signal given from an outside source to conduct said operation of the switching element intermittently.  
     
     
         15 . A power supply apparatus according to  claim 12  or  13  further comprising a load current detecting means for detecting a load current of said power supply apparatus, wherein said control circuit is driven in response to the load current detected by the load current detecting means.  
     
     
         16 . A power supply apparatus according to  claim 15 , wherein said load current, said duty cycle, or said oscillating frequency is detected with the aid of a comparator.  
     
     
         17 . A power supply apparatus according to any one of claims  15 , wherein said load current is detected with the aid of a comparator having a hysteresis characteristic.  
     
     
         18 . A power supply apparatus according to any one of claims  15 , wherein said load current is detected with the aid of a comparator and a time delay element.  
     
     
         19 . A power supply apparatus according to any one of  claims 12  to  18 , wherein said switching means comprises a zero cross switch and said switching means is operated at a zero cross point.  
     
     
         20 . A power supply apparatus according to claims  19 , wherein a zero cross point having a certain directivity is selected and said switching means is operated at the selected zero cross point.  
     
     
         21 . A power supply apparatus according to any one of  claims 14  to  20 , wherein said signal detecting means for detecting a signal given from an outside or said load current detecting means is arranged at a secondary side of said transformer, and the signal detected by these means is transferred to a primary side of said transformer by using another transformer, or a third coil or a photo coupler.  
     
     
         22 . A power supply apparatus comprising an AC power supply and a transformer, wherein an input voltage is supplied to a primary side of said transformer in a divided condition.  
     
     
         23 . A power supply apparatus according to  claim 22 , wherein said voltage divided condition is obtained in response to a signal given from the outside.  
     
     
         24 . A power supply apparatus according to  claim 22 , further comprising a load current detecting means for detecting a load current of said power supply apparatus, wherein said voltage divided condition is obtained in response to the load current detected by the load current detecting means.  
     
     
         25 . A power supply apparatus according to  claim 23  or  24 , wherein said signal detecting means for detecting a signal given from the outside or said load current detecting means is arranged at a secondary side of said transformer, and the signal detected by these means is transferred to a primary side of said transformer by using another transformer, a third coil or a photo coupler.  
     
     
         26 . A power supply apparatus comprising an AC power supply, an active filter or an inverter, a control circuit for controlling an operation of said active filter or an inverter and a power supply for driving said control circuit, wherein a capacitor is provided between said AC power supply and said power supply for driving said control circuit so that said power supply for driving said control circuit is operated by using an electrical current going through a reactance component of said capacitor.  
     
     
         27 . A power supply apparatus according to  claim 26 , wherein a choke coil of said active filter or said inverter comprises a tap or a second coil, so that when a main unit to which said power supply apparatus is applied is in a driving condition an electrical power is also supplied to a drive means for driving said active filter or said inverter from said tap or said second coil.  
     
     
         28 . A power supply apparatus according to  claim 26 , wherein said active filter or said inverter comprises at least one capacitor on its output circuit, so that when a main unit to which said power supply apparatus is applied is in a driving condition an electrical power is also supplied to a drive means for driving said active filter or said inverter through said capacitor.