Abstract:
A power supply device is provided. The power supply device includes: an AC power output unit storing and outputting an AC power; a rectifier unit rectifying an output of the AC power output unit; a DC output unit outputting an output from the rectifier unit as a DC power; and a standby power reduction unit detecting a signal regarding whether the AC power is inputted or not and discharging a standby power stored in the AC power output unit in response to the detected signal.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims priority under 35 U.S.C. 119 to Korean Patent Application No. 10-2010-0136066, filed on Dec. 27, 2010, which is hereby incorporated by reference in its entirety. 
     BACKGROUND 
     The present disclosure relates to a power supply device. 
     In general, in order to use an electrical appliance such as a copying machine, a video recorder, a microwave oven, a dish washer, a cell phone charger, a computer, a monitor, a printer, a facsimile, and a washing machine in a home or an office, commercial power is supplied via connecting a plug, wired to the electrical appliance, to a wall outlet installed at the wall of a building or a multi tap extending from the wall outlet. 
     Moreover, while the electrical appliance is installed, the plug of an electrical appliance connected to a wall outlet installed at the wall of a building or a multi tap typically maintains a constant state of being connected to each other, so that commercial power is continuously supplied regardless of its use. When commercial power is constantly supplied through the plug of an electrical appliance connected to a wall outlet, the time required for standing by a certain function in a power off state takes a larger part of a total usage time than the time required for performing an original function of the electrical appliance. Therefore, the consumption of power vampire, which plays an important role in determining an energy efficiency rating of an electrical appliance, is excessively high. 
     In order to completely prevent the consumption of power vampire in an electrical appliance, a user may directly separate the plug of an electrical appliance from a wall outlet or a multi tap or may turn off a power switch in each power outlet of a multi tap. As a result, a commercial power (i.e., a main power) supplied to the electrical appliance is completely cut off. However, this is very cumbersome. Due to this reason, the complete standby power off is not widely used. 
     Additionally, as a commercial power (i.e., a main power) is constantly supplied to an electrical appliance through a plug connected to a wall outlet, components of the electrical appliance become deteriorated thereby reducing its lifecycle. Also, when an over current occurs due to a bolt of lightning, it occasionally flows into the electrical appliance along its power line to damage the electrical appliance. 
     Furthermore, various devices, which cut off Power Vampire when it is determined by recognizing power consumption that power is off, have been developed and mounted on an electrical appliance. However, in such a case, the electrical appliance is not turned on when a remote controller is used for a certain operation. Thus, a user may personally turn on a power switch mounted on the electrical appliance and this causes inconvenience. 
     Moreover, if a commercial power (i.e., a main power) supplied to an electrical appliance is cut off, its timer mode becomes useless. 
     SUMMARY 
     Embodiments provide a power supply device having a power vampire reduction circuit. 
     Embodiments also provide a power supply device having improved reliability by detecting an input state of power and reducing standby power automatically. 
     In one embodiment, a power supply device includes: an AC power output unit storing and outputting an AC power; a rectifier unit rectifying an output of the AC power output unit; a DC output unit outputting an output from the rectifier unit as a DC power; and a standby power reduction unit detecting a signal regarding whether the AC power is inputted or not and discharging a standby power stored in the AC power output unit in response to the detected signal. 
     The details of one or more embodiments are set forth in the accompanying drawings and the description below. Other features will be apparent from the description and drawings, and from the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a circuit diagram illustrating a power supply device according to a first embodiment. 
         FIG. 2  is a view of the standby power reduction unit of  FIG. 1 . 
         FIG. 3  is a circuit diagram of the standby power reduction unit of  FIG. 1 . 
         FIG. 4  is a circuit diagram of a power supply device according to a second embodiment. 
         FIG. 5  is a circuit diagram of the standby power reduction unit of  FIG. 4 . 
         FIG. 6  is a circuit diagram of a standby power reduction unit according to a third embodiment. 
         FIG. 7  is a circuit diagram of a standby power reduction unit according to a fourth embodiment. 
         FIG. 8  is a circuit: diagram of a standby power reduction unit according to a fifth embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Reference will now be made in detail to the embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings. 
       FIG. 1  is a circuit diagram illustrating a power supply device according to a first embodiment. 
     Referring to  FIG. 1 , the power supply device  100  includes a power unit  101 , an AC power output unit  102 , a rectifier unit  103 , a Power Factor Correction (PFC) unit  104 , a DC power output unit  105 , a standby unit  106 , and a standby power reduction unit  110 . 
     The AC power output unit  102  stores and outputs an AC power inputted from the power unit  101 . The AC power includes commercial power. The AC power input unit  102  includes a capacitor Cx, for example. The capacitor Cx is connected in parallel to the both terminals of the power unit  101  and charges and discharges an AC power. As another example, the AC power output unit  102  may include a filter but is not limited thereto. 
     The rectifier unit  103  rectifies and outputs an AC power outputted from the AC power output unit  102 . The rectifier unit  103  may include a bridge diode and wave-rectifies and outputs an AC power. 
     An input capacitor Cin is connected to the both output terminals of the rectifier unit  103  and removes a ripple of a DC power outputted from the rectifier unit  103  and outputs the DC power to the PFC unit  104 . The PFC unit  104  may include a line filter and a capacitor device but is not limited thereto. 
     The PFC unit  104  improves a power factor of the voltage rectified by the rectifier unit  103 , converts the rectified voltage into a DC voltage, and outputs the DC voltage. The DC output unit  105  converts an output voltage of the PFC unit  104  into a DC voltage necessary for a load and outputs the DC voltage. The DC output unit  105  may include a DC converter or a transformer. 
     The standby unit  106  receives an input power of the PFC unit  104 , outputs the input power as a standby power, and controls an operation status of a system in response to an external control signal. 
     The standby power reduction unit  110  is connected to at least one of the both terminals of the power unit  101 , detects whether an inputted power V AC     —     L  and V AC     —     N  is supplied, is turned off (i.e., a n operating mode) when it is detected that the AC power is more than a predetermined level (i.e., an operating voltage), and is turned on (i.e., a standby mode) when it is detected that the AC power is not more than the predetermined level (i.e., an operating voltage). 
     If an AC power of the standby power reduction unit  110  is not supplied, power is not supplied to the power unit  101 . At this point, the standby power reduction unit  110  provides a discharge path for lowering a power (hereinafter, referred as a standby power) stored in the AC power output unit  102  to be lower than a predetermined voltage within a predetermined time. 
     The standby power reduction unit  110  is connected to the both terminals of the AC power output  102  and discharges a standby power of the AC power output unit  102  to a ground terminal. 
     The standby power reduction unit  110  operates by receiving a bias voltage from the standby unit  106  or the external and the bias voltage may be supplied while the standby power is reduced even if the power of the power unit  101  is off. 
     The standby power reduction unit  110  is turned on when the AC power is not supplied and provides a discharge path of the stored standby power, thereby reducing the standby power stored in the AC power output unit  102  for a predetermined time. Accordingly, the standby power stored in the AC power output unit  102  may be lowered than a predetermined voltage for a predetermined time, so that damages to a device or a user due to a high AC voltage may be prevented. The standby power reduction unit  110  may satisfy a safety standard that energy stored in the AC power output unit  102  should be lower than about 60 V within 2 seconds. 
     Referring to  FIG. 2 , the standby power reduction unit  110  includes an AC power detection unit  111 , a bias power supply unit  113 , a standby power rectifier unit  114 , and a discharge unit  115 . 
     The AC power detection unit  111  is connected to a second line V AC     —     N  among the both terminals of the power unit  101  and detects a power S 1  applied to the second line V AC     —     N  of the power unit  101 . As another example, the AC power detection unit  111  may be connected to a first line V AC     —     L  but is not limited thereto. The first line V AC     —     L  may be a positive polarity terminal and the first line V AC     —     N  may be a negative polarity terminal. 
     The AC power detection unit  111  turns off an operation of the bias voltage supply unit  113  in a power mode and turns on an operation of the bias voltage supply unit  113  in a standby mode. That is, the AC power detection unit  111  controls an operating voltage of the bias voltage supply unit  113  according to whether power is supplied or not. 
     The bias voltage supply unit  113  controls an output of a bias voltage according to an operation status of the AC power detection unit  111  and outputs a bias voltage to the standby unit  106  in a standby mode. 
     The discharge unit  115  is turned on by a voltage of the standby unit  106  and the standby power rectifier unit  114  rectifies a standby power stored in the AC power output unit  102 . The standby power rectifier unit  114  is connected to the both terminals of the AC power output unit  102  and rectifies and outputs the standby powers P 1  and P 2  applied to one of the both terminals of the AC power output unit  102 . 
     The discharge unit  115  outputs the standby power S 3  rectified by the standby power rectifier unit  114  to the ground terminal through conduction. Accordingly, the discharge unit  115  provides a discharge path of a standby power in a standby mode. 
       FIG. 3  is a circuit diagram of the standby power reduction unit of  FIG. 1 . 
     Referring to  FIGS. 2 and 3 , the AC power detection unit  111  is connected to a first line V AC     —     N  to which an AC power is applied and receives an AC power through the first line V AC     —     N . The first line V AC     —     N  may be a negative polarity terminal 
     The AC power detection unit  111  includes an operating voltage detection circuit  111 A and a comparison device  111 B. The operating voltage detection circuit  111 A detects a level of the AC power and then, outputs it as an operating voltage of the comparison device  111 B. The comparison device  111 B is conducted or outputs a reference voltage according to an operating voltage level of the operating voltage detection circuit  111 A. 
     The operating voltage detection circuit  111 A includes a first capacitor C 1 , a third diode D 3 , a fourth diode D 4 , first to third resistors R 1 , R 2 , and R 3 , second and third capacitors C 2  and C 3 , and a fourth capacitor C 4 . Here, the first capacitor C 1  and the third resistor R 3  constitute a charge/discharge circuit. The third diode D 3  is used for protection. The second and third capacitors C 2  and C 3  are a ripple removing circuit and are connected to the first and second resistors R 1  and R 2  to constitute a differential circuit or a low pass filter. The first and second resistors R 1  and R 2  constitute a voltage divider circuit and the fourth diode D 4  is connected to a reverse current path. 
     The first capacitor C 1  is connected to a second line V AC     —     N . An anode of the third diode D 3  and a cathode of the fourth diode D 4  are connected to the first capacitor. C 1 . An anode of the third diode D 4  is connected to a ground terminal. 
     The first resistor R 1  and the second resistor R 2  are connected in series to the third diode D 3 . The second capacitor C 2  is connected in parallel to between the first resistor R 1  and the second resistor R 2 . The other terminal of the second capacitor C 3  is grounded. 
     The third resistor R 3  is connected in parallel to the second resistor R 2 . The third capacitor C 3  is connected in parallel to between the third resistor R 3  and the second resistor R 2 . The other terminal of the third capacitor C 3  is grounded. A reference terminal Vref of the comparison device  111 B is connected to a connection node between the second resistor R 2  and the third resistor R 3 . In the comparison device  111 B, a second terminal (−) is connected to the ground terminal and the first terminal (+) is connected to the bias voltage supply unit  113 . The fourth capacitor C 4  is connected to between the reference terminal and the first polarity terminal of the comparison device  111 B. 
     The operating voltage detection circuit  111 A charges an inputted current IAC on the first capacitor C 1  and discharges the current I AC  through the resistor RI, the second capacitor C 2 , the second resistor R 2 , and the third capacitor C 3 . The operating voltage detection circuit  111 A detects an operating voltage of the comparison terminal  111 B. 
     An operating voltage divided by the second resistor R 2  and the third resistor R 3  is applied to the reference terminal of the comparison device  111 B. The comparison device  111 B outputs a low output VKA to the second terminal (+) when the operating voltage higher than an internal reference voltage is applied and an output VKA of the second terminal (+) is raised when the operating voltage lower than the internal reference voltage is applied. 
     The comparison device  111 B as an integrated device includes a shunt regulator or a comparator. The comparison device  111 B compares an input operating voltage with an internal reference voltage. The comparison device  111 B outputs a high signal if the input operating voltage is lower than the internal reference voltage and outputs a low signal if not. Here, the comparison device  111 B outputs a low signal in a power mode and outputs a high signal in a standby mode. 
     If the comparison device  111 B is a shunt regulator, the reference terminal is connected to the resistors R 2  and R 3 , an anode terminal is connected to the ground terminal, and a cathode terminal is connected to the bias power supply unit  113 . 
     The bias voltage supply unit  113  includes a first switching device Q 1 . A bias voltage VCC inputted from a standby unit is applied to a gate terminal and a drain terminal of the first switching device Q 1 . The first switching device Q 1  is turned on and outputs the bias voltage VCC when a high signal is outputted from the AC power output unit  111 . The first switching device Q 1  is turned off and may not output the bias voltage VCC when a low signal is outputted from the AC power output unit  111 . 
     The first switching device Q 1  is a MOS transistor, for example, a Metal oxide Semiconductor Field-Effect Transistor (MOSFET). As another example, the first switching device Q 1  may be a bipolar junction transistor. 
     An output signal S 2  of the bias voltage supply unit  113  is inputted to the discharge unit  115 . The discharge unit  115  includes a second switching device Q 2 , which is turned on/off according to an output signal S 2  of the bias voltage supply unit  113 . In the second switching device Q 2 , voltage divider resistors R 7  and R 8  are connected to a gate terminal and an output S 2  of the bias voltage supply unit  113  is inputted to the gate terminal; a discharge resistor RX is connected to a drain terminal and an output S 3  of the standby power rectifier unit  114  is inputted to the discharge resistor RX; and a source terminal is grounded. The second switching device Q 2  may be a MOS transistor, for example, a MOSFET. As another example, the second switching device Q 2  may be a bipolar junction transistor. 
     Since the standby power rectify unit  114  includes diodes D 1  and D 2 , it operates when a standby power has a positive or negative polarity. 
     When the first switching device Q 1  of the bias voltage supply unit  113  is turned on, the second switching device Q 2  is turned on. When the second switching device Q 2  is turned on, an output S 3  of the standby power rectify unit  114  is discharged to the ground terminal. 
     Here, each device of the standby power reduction unit  110  affects a time from the start of a standby mode to the start of an operation of the discharge resistor RX. A resistance value of the discharge resistor RX determines a time from the start of an operation of the second switching device Q 2  to the start of a voltage drop below a predetermined value. Accordingly, a resistance value of the discharge resistor RX is reduced to make a discharge time of a standby power faster. 
       FIGS. 4 and 5  are detailed configuration of a power supply device and a standby power reduction unit according to a second embodiment. 
     Referring to  FIG. 4 , the standby power reduction unit  110  receives a standby power through an output terminal of the rectifier unit  103 , i.e., a positive polarity terminal, and then discharges it. Without the additional standby power rectifier unit of  FIG. 2 , the rectified power Vin of the rectifier unit  103  is discharged. 
     The standby power reduction  110  operates in a standby mode and the standby power stored in the AC power output unit is applied to the standby power reduction unit  110  through the rectifier unit  103  and then is discharged. Additionally, the power stored in the input capacitor Cin connected to the output terminal of the rectifier unit  103  may be applied to the standby power reduction unit  110  and then may be discharged. 
     The standby power reduction unit  110  may discharge a voltage of the capacitor Cx of the AC power output unit  102  and a voltage of the input capacitor Cin connected to the output terminal of the rectifier unit  103  to be less than a predetermined level and may provide a discharge path in a standby mode. 
       FIG. 5  is a circuit diagram of the standby power reduction unit of  FIG. 4 . Like  FIGS. 4 and 5 , since a standby power is discharged through a path of the rectifier unit  103 , the first and second diodes of the standby power rectifier unit shown in  FIG. 3  may not be required. 
       FIG. 6  is a circuit diagram of a standby power reduction unit according to a third embodiment. 
     Referring to  FIG. 6 , the standby power reduction unit connects the resistor R 10  instead of the diode D 4  of  FIG. 3  to a reverse current path connected to the first capacitor C 1 , thereby allowing a reverse current of the first capacitor C 1  to flow through resistance. 
       FIG. 7  is a circuit diagram of a standby power reduction unit according to a fourth embodiment. 
     Referring to  FIG. 7 , the AC power detection unit  111  of the standby power reduction unit includes an operating voltage detection circuit  11 A and a switching device Q 3 . The third switching device Q 3  may be a MOSFET and, as another example, may be a bipolar junction transistor. 
     When the third switching device Q 3  is in a standby mode, a low signal is applied to a gate terminal and a bias voltage Vcc is applied to a base terminal of the first switching device Q 1 , so that the third switching device Q 3  operates. Accordingly, the first switching device Q 1  operates through conduction. Due to an operation of the first switching device Q 1 , the second switching device Q 2  is conducted, thereby discharging a standby power to a ground terminal through the discharge resistor Rx connected to a drain terminal. 
       FIG. 8  is a circuit diagram of a standby power reduction unit according to a fifth embodiment. 
     Referring to  FIG. 8 , the AC power detection unit  111  of the standby power reduction unit is connected to the AC power V AC     —     L  of a positive polarity. That is, the AC power detection unit  111  may be selectively connected to a positive polarity or a negative polarity of the power unit but is not limited thereto. 
     The standby power reduction unit according to embodiments may be applied to image devices such as a plasma display panel (PDP) TV, a liquid crystal display (LCD) TV, a light emitting diode (LED) TV, and a monitor and also various lighting devices. 
     According to embodiments, a relay may not be required. 
     According to embodiments, a relay having a large size is not required, so that electronic products such as TVs or monitors may have a thin thickness. 
     According to embodiments, a reliable standby power reduction device may be provided. 
     Although embodiments have been described with reference to a number of illustrative embodiments thereof, it should be understood that numerous other modifications and embodiments can be devised by those skilled in the art that will fall within the spirit and scope of the principles of this disclosure. More particularly, various variations and modifications are possible in the component parts and/or arrangements of the subject combination arrangement within the scope of the disclosure, the drawings and the appended claims. In addition to variations and modifications in the component parts and/or arrangements, alternative uses will also be apparent to those skilled in the art.