Electricity: power supply or regulation systems – Output level responsive – Using a three or more terminal semiconductive device as the...
Reexamination Certificate
2002-03-06
2004-01-06
Patel, Rajnikant B. (Department: 2838)
Electricity: power supply or regulation systems
Output level responsive
Using a three or more terminal semiconductive device as the...
C363S021160
Reexamination Certificate
active
06674271
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims the benefit of Korean No. 2001-12241, filed Mar. 9, 2001, in the Korean Industrial Property office, the disclosure of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a system to which power is supplied using a switching mode power supply (SMPS), and more particularly, to a power supply control apparatus, which is capable of reducing power consumption by a SMPS in the system, such as a facsimile machine, for transmitting, receiving, and outputting data, and a method thereof.
2. Description of the Related Art
A switching mode power supply (SMPS) provides electric power to electric loads with a switching operation. A conventional SMPS, which is included in a system, such as a facsimile machine, for outputting data, is shown in FIG.
1
.
FIG. 1
illustrates an example in which power is supplied to a system controller (CPU) included in a system and peripherals from the SMPS included in the system.
Referring to
FIG. 1
, in the conventional SMPS, an alternating current (AC) voltage is changed into a direct current (DC) voltage by a rectifier circuit
101
, and the DC voltage is transmitted to a driving voltage-applying portion
105
and a primary winding Np when an AC switch SW
1
is turned on. In this case, a driving voltage Vcc is not applied to a pulse width modulation-integrated circuit PWM-IC
110
, and thus power is induced in a primary winding Np. The driving voltage-applying portion
105
includes start up resistors R
1
and R
2
, a capacitor C
1
, a resistor R
3
, and a diode D
1
and supplies the driving voltage Vcc to the PWM-IC
110
. That is, when the DC voltage is applied to the driving voltage-applying portion
105
, the capacitor C
1
is charged through the start up resistors R
1
and R
2
. Due to the voltage in the capacitor C
1
, the driving voltage Vcc is supplied to a terminal P
1
of the PWM-IC
110
. As a result, the PWM-IC
110
outputs a signal for controlling a switching operation of a field-effect transistor (FET) through a terminal P
3
. An output switching control signal is applied to a gate terminal of the FET through a resistor R
4
. A resistor R
5
is connected between the FET and a ground. When the FET is turned on, the primary winding Np in a transformer
115
allows the power to be induced in secondary windings Ns
1
and Ns
2
and in an auxiliary winding Na.
When the power is induced in the auxiliary winding Na of a transformer
115
, the driving voltage Vcc is supplied to the PWM-IC
110
through the diode D
1
and the resistor R
3
in the driving voltage-applying portion
105
. In a case where the FET is turned off and thus power is not induced in the auxiliary winding Na, the driving voltage Vcc is supplied to the PWM-IC
110
by the voltage charged in the capacitor C
1
.
As above, the power, which is induced in the auxiliary winding Na and the secondary windings Ns
1
and Ns
2
, is determined in accordance with the switching operation of the FET. The switching operation of the FET is performed in accordance with a duty cycle, which is determined in the PWM-IC
110
according to a feedback signal provided from a feedback portion
120
through a terminal P
4
. The feedback portion
120
senses a voltage Vo
1
output to the system controller (not shown) and provides a feedback signal to the terminal P
4
of the PWM-IC
110
so that the output voltage Vo
1
is maintained at a constant level. The PWM-IC
110
measures the peak value of current flowing into the FET through a terminal P
2
and thereby prevents over-current from flowing into the FET. That is, in a case where it is recognized that the over-current flows into the FET in accordance with the measured peak value of the current, the PWM-IC
110
shuts down the FET.
Meanwhile, AC power induced in the secondary windings Ns
1
and Ns
2
is smoothed into a DC voltage by diodes D
2
and D
3
and capacitors C
2
, C
3
, C
4
, and C
5
, respectively, and thus is supplied to peripherals (not shown) and to the system controller.
However, when an AC switch SW
1
is turned off, the SMPS shown in
FIG. 1
stops working to supply the power to the peripherals and the system controller, as described above.
Likewise, the conventional SMPS continuously supplies power to the system controller and the peripherals in a case where the AC switch SW
1
is not turned off. Thus, in order to reduce power consumption, the AC switch SW
1
must be turned off when the system is not used. However, it is unknown when the output of data is required in the system, such as a fax machine, and thus the system always turns on the AC switch SW
1
. Thus, the power is continuously applied to the system controller and to the peripherals even when the system is not used, thereby unnecessarily consuming power.
To solve the problem, in the related art, a sleep mode has been suggested for cutting off power supplied from the SMPS to all of the peripherals of the system except the system controller in a case where it is recognized by the system controller that the system has not performed an operation for a predetermined period of time, has been suggested. However, even in a case where the sleep mode is set, the SMPS continuously supplies power to the controller, and the work for supplying power from the SMPS to the peripherals is continuously performed even though the power supply of the SMPS to the peripherals is cut off. Thus, even in a case where the sleep mode is set, power continues to be consumed in the SMPS.
SUMMARY OF THE INVENTION
To solve the above problems, it is a first object of the present invention to provide a power supply control apparatus, which controls the operation of a switching mode power supply (SMPS) so that power consumption in a system including the SMPS is reduced, and a method thereof.
It is a second object of the present invention to provide a power supply control apparatus, which controls to operate a SMPS only when power to a system is required, without a need for an alternating current (AC) switch, and a method thereof.
It is a third object of the present invention to provide a power supply control apparatus so that a system, such as a fax machine, is automatically turned on only when the output of data is required, and a method thereof.
Additional objects and advantageous of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
Accordingly, to achieve the above and other objects, according to the present invention, there is provided an apparatus for controlling power supply to each part in a system including a system controller and a data output device. The apparatus includes a switch that is set to an ON state by a user's contact, a detection portion which is connected in parallel with the switch and for detecting whether a signal for requiring a predetermined operation is applied to the system from outside, and a power supply portion for supplying power to each part of the system when the switch is temporarily set to the ON state or a second signal for indicating the detection of the signal is input from the detection portion, and for terminating the power supply to each part in the system including the system controller when a power off signal is applied from the system controller when the switch is set to an OFF state or when the second signal for indicating the detection of the signal is not input from the detection portion.
In order to achieve the above and other objects, according to the present invention, there is provided an apparatus for controlling power supply to a system having a system controller and peripherals requiring the power supply. The apparatus includes a switch that is controlled to turn on/off by a user, a first switching unit, a pulse width modulation (PWM) portion that supplies a pulse signal for controlling the switching operation of the first switching unit when a driving voltage is applied, a transformer that
Cho Jong-hwa
Choo Jong-yang
Kwon Joong-gi
Ryu Han-chung
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