KR20100119065A - Power supply for plasma display pannel - Google Patents

Abstract

PURPOSE: A power supply for a plasma display panel is provided to prevent a fire and a shock accident due to a short circuit by blocking current flowing into an output terminal. CONSTITUTION: A power supply device comprises a rectifier(20) and an inverter(60). The inverter includes a switch(61), a transformer(63), and a current transformer. An AC current conversion unit changes the DC current passing through the switch into DC current. The transformer boosts the AC current. The current transformer reduces the AC current by a certain ratio. A protection circuit(70) blocks the DC current flowing into an inverter.

Description

Power supply of plasma display panel {POWER SUPPLY FOR PLASMA DISPLAY PANNEL}

The present invention relates to a power supply device for a plasma display panel. Specifically, when an abnormal state is detected by detecting an abnormal state from a current of an output terminal, the current of the output terminal is blocked to prevent a fire or human electric shock due to a short circuit. The present invention relates to a power supply of a plasma display panel.

The plasma display panel is a display device using light emitted from an inert gas. Plasma display panels can be manufactured in large, thin shapes, which makes them suitable as display devices for large commercials.

When power is applied to the discharge electrodes provided on the upper and lower surfaces of the plasma display panel, ultraviolet rays are emitted from an inert gas in the discharge space inside the plasma display panel, and when the emitted ultraviolet rays excite the fluorescent substance, visible light is emitted from the fluorescent substance and is visible. The advertisement is displayed by the rays.

1 illustrates a configuration of a power supply device 100 of a conventional plasma display panel.

As shown in FIG. 1, the conventional power supply device 100 receives a rectifier 20 to receive alternating current from a commercial AC power source 10 and converts the current into a direct current, and inputs the rectifier 20 while maintaining a constant power factor. The power factor correction unit 30 outputs the received direct current, and the inverter 40 converts the direct current output from the power factor correction unit 30 into alternating current of high voltage and high frequency. The alternating current output from the inverter 40 is applied to the discharge electrodes (anode and cathode) of the plasma display panel 50 so that light is emitted from the plasma display panel 50.

However, since the power supply of the conventional plasma display panel does not detect an abnormal state in which the output terminal is shorted to the outside or in contact with the human body, there is a problem that a fire and an electric shock accident may occur due to a short circuit current. In addition, since the power used in the plasma display panel is a high-voltage alternating current, a large short-circuit current may lead to a large fire accident and increase the probability of death due to electric shock.

The present invention was devised to solve the above problems, and by detecting an abnormal state such as a short circuit or human body contact and blocking the current flowing to the output terminal, a plasma display panel which can prevent a fire and human electric shock caused by a short circuit current. An object of the present invention is to provide a power supply.

To this end, the power supply device of the plasma display panel according to the present invention, the AC output from the inverter including a rectifier for receiving AC from the AC power source and converts into DC and an inverter for converting the DC output from the rectifier into AC. A power supply for a plasma display panel for supplying a plasma to a plasma display panel, the inverter comprising: a switch for passing a direct current output from the rectifying unit, an alternating current conversion unit for converting a direct current passing through the switch into an alternating current, and the alternating current A transformer for boosting and outputting the alternating current output from the converter, and a current transformer for reducing the alternating current output from the transformer at a predetermined ratio, and determining whether it is an abnormal state or a normal state from the current cut down by the current transformer, On state of the switch if If maintained, and the abnormal state is characterized in that it further comprises a protection circuit for blocking a direct current to switch off the input to the inverter.

As described above, according to the present invention, since the power supply of the plasma display panel detects an abnormal state such as a short circuit or a human contact from the current at the output terminal and cuts off the current at the output terminal when an abnormal state is detected, a fire and a human body caused by a short circuit current It is effective to prevent electric shock.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2 shows a power supply device 200 of a plasma display panel according to the present invention.

As shown in Figure 2, the power supply device 200 of the present invention is a protection circuit unit 70 is added to the conventional power supply device 100 of FIG. The protection circuit unit 70 stops the operation of the inverter 40 when the abnormal state is detected by checking the abnormal state from the current output from the inverter 40. When the operation of the inverter 40 is stopped, the alternating current of the high voltage output from the inverter 40 is cut off.

The inverter 40 includes a switch 61 for passing a direct current output from the power factor correction unit 30, an alternating current conversion unit 62 for converting a direct current passed through the switch 61 into alternating current, and an alternating current conversion unit 62. It includes a transformer (63) for boosting and outputting the alternating current output from the. The current output from the transformer 63 is applied to the plasma display panel 50 and input to the protection circuit unit 70. The switch 61 may be a transistor such as a FET as the semiconductor switch.

The protection circuit unit 70 determines whether it is an abnormal state or a normal state from the current output from the inverter 60. When detecting the abnormal state, the protection circuit unit 70 turns off the switch 61 to cut off the DC input to the inverter 60. When the direct current input to the inverter 60 is cut off, the output of the inverter 40 is also cut off. In the normal state, the on state of the switch 61 is maintained.

3 shows an internal configuration of the inverter 60 and the protection circuit unit 70.

As shown in FIG. 3, the inverter 60 further includes a current transformer 64 for reducing the alternating current output from the transformer 60 at a predetermined ratio. Since the alternating current output from the transformer 63 has a large current value so as to drive the plasma display panel 50, it is difficult to directly use it as an input of the protection circuit unit 70. Therefore, the current transformer 64 is installed at the output terminal of the transformer 60 to convert the current into a small value that can be used in the protection circuit unit 70.

The protection circuit unit 70 determines whether it is an abnormal state or a normal state from the photocoupler 72 for turning on or off the switch 61 of the inverter 60 and the current cut down from the current transformer 64. In this case, the photocoupler 72 is maintained in an on state, and in an abnormal state, the photocoupler 72 is turned off. When the check circuit 71 detects an abnormal state, the switch 61 is turned off while the photocoupler 72 is turned off. In the normal state, the switch 61 is turned on while the photo coupler 72 is kept turned on. State is maintained.

4 shows the internal structure of the check circuit 71 in detail.

As shown in FIG. 4, the check circuit 71 includes a direct current converter 711 for converting the alternating current output from the current transformer 64 into direct current, and a current (voltage) output from the direct current converter 711. If is greater than or equal to a certain value outputs a low and if less than the current detection unit 712 and, if the current comes from the DC converter 711 is input high and if the current does not come from the DC converter 711 to low A NAND gate 713 having a first input terminal A and a second input terminal B for receiving the output of the current detector 712, and turned on in accordance with the output of the NAND gate 713. Or a transistor 714 that is turned off, and a relay 715 that turns the photocoupler 715 on or off in response to the transistor 714 being turned on or off.

In the exemplary embodiment of the present invention, the normal state refers to a state in which a load is connected to the output terminal of the power supply device 200, that is, a state in which the plasma display panel 50 is connected and operated, and the abnormal state refers to the power supply device 200. The plasma display panel 50 is not connected to the output terminal of the (open state), or the human body is in contact with the output terminal.

In the steady state, the alternating current reduced by the constant ratio in the current transformer 64 is converted into direct current by the DC converter 711. The current of the DC converter 711 is input to the first input terminal A as a high signal (logic value 1). The current detector 712 outputs a high signal when the current (voltage) of the DC converter 711 is smaller than a predetermined value, and outputs a low signal (logic value 0) when larger than the predetermined value. In the normal state, since the current (voltage) of the DC converter 711 is smaller than a predetermined value, the current detector 712 outputs a high signal.

Since the NAND gate 713 receives a high signal through the first input terminal A and a high signal through the second input terminal B, the output of the NAND gate 713 becomes low. When the output of the NAND gate 713 is low, the transistor 714 and the relay 715 are turned off. When the relay 715 is turned off, the photocoupler 72 is turned on. When the photocoupler 72 is on, the switch 61 is also turned on, and a normal output is made by the inverter 60.

Next, the case of an abnormal state is demonstrated. First, when the output terminal of the inverter 60 is open, since no current flows through the output terminal, a low signal is input to the first input terminal A. FIG. No current (voltage) is detected in the current detector 712, which means that the current (voltage) of the DC detector 712 is smaller than a predetermined value, so the current detector 712 outputs a high signal.

Since the NAND gate 713 receives a low signal through the first input terminal and a high signal through the second input terminal, the output of the NAND gate 713 becomes high. When the output of the NAND gate 713 becomes high, the transistor 714 and the relay 715 are turned on, and when the relay 715 is turned on, the photocoupler 72 is turned off. When the photocoupler 72 is turned off, the switch 61 is also turned off to cut off the output of the inverter 60.

When the output terminal of the inverter 60 is shorted or contacts the human body, a large current flows through the output terminal. The alternating current sensed through the current transformer 64 is converted into direct current by the DC converter 711 and input to the first input terminal A as a high signal. Since the current (voltage) of the DC converter 711 input to the current detector 712 is greater than a predetermined value, the current detector 712 outputs a low signal. Since the NAND gate 713 receives a high signal through the first input terminal and a low signal through the second input terminal, the output of the NAND gate 713 becomes high.

When the output of the NAND gate 713 becomes high, the transistor 714 and the relay 715 are turned on, and when the relay 715 is turned on, the photocoupler 72 is turned off. When the photocoupler 72 is turned off, the switch 61 is also turned off to cut off the output of the inverter 60.

Table 1 below shows the state (operation) of each element of the protection circuit unit 70 according to a normal or abnormal state.

NAND gate
input NAND gate output
transistor

relay

Photocoupler

switch

Output
A B Y Steady state One One 0 off off On On Print Open 0 One One On On off off block Short circuit One 0 One On On off off block Human contact One 0 One On On off off block

In Table 1, in the normal state, the output of the NAND gate goes low, and in turn, the transistor is turned off, the relay is turned off, the photocoupler is turned on, and the switch is turned on. Is output.

On the other hand, in an abnormal state (open, short circuit, human body contact), the output of the NAND gate goes high, and in turn, the transistor on, relay on, photocoupler off, switch off, switch off, the output terminal of the inverter 60, that is, power supply The current is cut off at the output of the device 200.

Those skilled in the art can improve or change the technical idea of the present invention in various forms. Therefore, it should be understood that the embodiments of the present invention described with reference to the drawings should not be construed as limiting the technical spirit of the present invention, and the protection scope of the present invention is limited only by the matters described in the claims.

1 is a configuration diagram of a power supply apparatus of a conventional plasma display panel.

2 is a configuration diagram of a power supply device of a plasma display panel according to the present invention;

3 is a view showing the internal configuration of the inverter and the protection circuit according to the present invention.

4 is a diagram showing details of an internal configuration of a check circuit according to the present invention;

<Description of the symbols for the main parts of the drawings>

10: AC power source 20: rectifier

30: power factor correction unit 40, 60: inverter

50: plasma display panel 61: switch

62: AC converter 63: transformer

64: current transformer 70: protection circuit

71: check circuit 72: photocoupler

100, 200: power supply device 711: DC converter

712: current detector 713: NAND gate

714 transistor 715 relay

Claims (6)

In the power supply of the plasma display panel for supplying the alternating current output from the inverter to the plasma display panel including a rectifying unit for receiving the alternating current from the alternating current to the direct current and the inverter for converting the direct current output from the rectifying unit into alternating current , The inverter includes a switch for passing a direct current output from the rectifying unit, an AC conversion unit for converting the direct current passed through the switch to AC, a transformer for boosting and outputting the AC output from the AC conversion unit, and in the transformer It includes a current transformer for reducing the output flow at a constant rate, It is determined whether the abnormal state or the normal state from the current cut down by the current transformer, and maintains the on state of the switch in the normal state, and in the abnormal state to turn off the switch to cut off the direct current input to the inverter The power supply of the plasma display panel further comprises a circuit. The method of claim 1, The protective circuit unit and the photo coupler for turning on or off the switch; And a check circuit for determining whether the photocoupler is in an abnormal state or a normal state from the current cut down by the current transformer and maintaining the on state of the photocoupler in a normal state, and turning off the photocoupler in an abnormal state. Power supply of plasma display panel. The method of claim 2, The check circuit includes a direct current converter for converting the alternating current output from the current transformer into direct current; A current detector for outputting a low when the current output from the DC converter is greater than or equal to a predetermined value and a high when less than a predetermined value; A NAND gate having a first input terminal input high when the current is input from the DC converter and a second input terminal input low when the current is not input from the DC converter; A transistor turned on or off according to the output of the NAND gate; And a relay for turning on or off the photocoupler according to the on or off of the transistor. The method of claim 3, The NAND gate outputs a low state in a normal state and a high state in an abnormal state, When the NAND gate outputs high, the photocoupler is turned off while the transistor and the relay are turned on, and the switch is turned off. And when the NAND gate outputs a low, the photocoupler is turned on while the transistor and the relay are turned off so that the switch is turned on. The method of claim 4, wherein The abnormal state is a state in which the output terminal of the inverter is open or shorted. When the output terminal of the inverter is open, a low is input to the first input terminal and a high is input to the second input terminal so that the output of the NAND gate becomes high. And a high input to the first input terminal and a low input to the second input terminal when the output terminal of the inverter is short-circuited so that the output of the NAND gate becomes high. The method of claim 4, wherein The normal state is a state in which a load is connected to the output terminal of the inverter, And a high input to the first input terminal and a high input to the second input terminal when the load is connected to the output terminal of the inverter, so that the output of the NAND gate is low.

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