Power supplying circuit and method

Details Power supplying circuit and method Power supplying circuit and method

1999-12-13

2001-10-23

Han, Jessica (Department: 2838)

Electric power conversion systems

Current conversion

Having plural converters for single conversion

C307S086000

Reexamination Certificate

active

06307762

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a power supplying circuit and method that are used for audio equipment also forth. In particular, the invention relates to a power supplying circuit and method for supplying standby power.
BACKGROUND OF THE INVENTION
In recent years, uses of electric products such as audio equipment and a television receiver incorporating a remote control using a remote controller and automatic time control using a timer, have increased. Such electric products commonly have a function that the operation power can be turned on/off by such remote control or automatic time control.
Where the operation power is turned on/off by the remote control or the automatic time control, a supply of standby power is needed to enable the remote control or the automatic time control, even when the operation power is in the off state. Examples of locations to which standby power need to be supplied are a remote controller light receiving section and a control microcomputer.
A power supplying circuit for supplying such standby power has a standby transformer for standby power and a main transformer for operation power. The supply of power to the remote controller light receiving section, the control microcomputer, and so forth is performed by the standby transformer, and the supply of power to a primary power relay during supply of operation power is also performed by the standby transformer. In this type of power supplying circuit, during supply of operation power only the standby transformer supplies power to the remote controller light receiving section, the control microcomputer, and so forth and the primary power relay. The standby transformer is required to have a capacity large enough to supply such power.
For example, a power supplying circuit for remote controller control of audio equipment is required to supply a current of 20 mA to the remote controller light receiving section, the control microcomputer, and so forth. After turning-on of the operation power, a current of 40 mA needs to be supplied to the primary power relay. Therefore, after turning-on of the operation power, a total current of 60 mA flows through the standby transformer. The standby transformer is required to have a rated current of more than 60 mA.
However, there is a problem that, in general, in a transformer having a large rated current, the standby current cannot be made small because of large loss including iron loss and copper loss.
The present invention has been made in view of the above circumstances in the art, and an object of the invention is therefore to provide a power supplying circuit and method that make it possible to use a transformer having a small rated current as a standby transformer.
SUMMARY OF THE INVENTION
To attain the above object, the invention provides a power supplying circuit comprising a primary power relay for opening and closing a main transformer; a standby transformer having a smaller power capacity than a power consumption capacity of the primary power relay; and power supply control means for causing the primary power relay to turn on the main transformer, and for causing supply of power from an output of the main transformer to the primary power relay after turning-on of the main transformer.
Only the standby transformer supplies a control current to a remote controller light receiving section, a control microcomputer, and so forth while the operation power is off, and supplies a drive current to the primary power relay at an instant when the primary power relay is activated. After activation of the primary power supply, both of the standby transformer and the main transformer supply a control current and a drive current for the primary power relay.


REFERENCES:
patent: 4751580 (1988-06-01), Fitzgerald et al.
patent: 5353215 (1994-10-01), Dinwiddie et al.

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