KR20180073318A - Apparatus for supplying power and display device comprising the same - Google Patents

Abstract

The present invention provides a power supply device capable of shutting off a path through which an overcurrent flows by determining whether an output terminal is short-circuited and controlling a plurality of switches. According to the present invention, the power supply device comprises: a power generating unit for converting an input voltage, inputted to an input terminal, into a drive voltage and outputting the drive voltage to an output terminal using the plurality of switches; a short circuit detection unit for determining whether the output terminal is short-circuited to generate a short circuit signal; and a switch control unit for controlling the plurality of switches in accordance with the short circuit signal.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a power supply device,

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a power supply device, and more particularly, to a power supply device capable of shutting off a path of an overcurrent and a display device including the power supply device.

Currently, various flat panel display devices capable of reducing weight and volume, which are disadvantages of cathode ray tubes (CRTs), are being developed. The flat panel display device includes a liquid crystal display, a field emission display, a plasma display panel, and a light emitting diode display.

Among flat panel display devices, a light emitting diode display device displays a desired image by supplying a current according to image information to a light emitting element formed in pixels arranged in a matrix using at least two thin film transistors.

The light emitting diode display device includes a power supply device for supplying a driving voltage for driving each pixel.

1 is a view showing an equivalent circuit of a conventional power supply device.

Referring to FIG. 1, a conventional power supply apparatus 10 includes an inductor L, a diode D, a capacitor C, and a switching transistor Tr. The inductor L is connected between the input terminal to which the input voltage Vin is applied and the first node N1, the diode D is connected between the first node N1 and the output terminal N2, and the capacitor C Is connected between the output terminal N2 and the ground terminal. The switching transistor Tr is connected between the first node N1 and the ground terminal.

The switching transistor Tr is switched according to the switching signal SW of the control unit so that energy is stored in the inductor L or energy stored in the inductor L is outputted. The capacitor C is connected in parallel with a load connected to the output terminal N2 to stably output the driving voltage. Here, the load may be a display panel of the flat panel display.

The conventional power supply device 10 having such a configuration has an input voltage Vin input by outputting the energy stored in the inductor L through the diode D to the output terminal N2 in accordance with the switching of the switching transistor Tr, To the driving voltage (VDD).

Meanwhile, in the conventional power supply apparatus 10, a short test must be performed in case the both ends of the capacitor C are short-circuited for safety reasons.

When a short test is conducted in this manner, both ends of the capacitor C are electrically connected to each other, which leads to the input terminal to which the input voltage Vin is applied, the inductor L, the diode D and the capacitor C A path through which the current along the line A flows can be generated. Thus, an overcurrent due to the input voltage Vin is generated according to the current path. The overcurrent flows through the diode D to generate a high temperature, and further, the generated high temperature is not discharged according to the heat dissipation structure of the power supply device 10. Therefore, there arises a problem that the diode is damaged due to overheating of the diode (D).

The present invention provides a power supply device capable of shutting off a path through which an overcurrent flows by controlling a plurality of switches by judging whether an output terminal is short-circuited.

The power supply apparatus according to the present invention includes a power generation unit, a short-circuit detection unit, and a switch control unit.

The power generator uses a plurality of switches to convert an input voltage input to an input terminal into a driving voltage and output the converted voltage to an output terminal.

The short-circuit detection unit determines whether the output terminal is short-circuited and generates a short-circuit signal.

The switch control unit controls the plurality of switches according to the short-circuit signal.

A plurality of switches are controlled by judging whether or not the output terminal of the power supply unit is short-circuited, so that a potential difference is generated in the power supply unit so that a path through which an overcurrent flows can be prevented. Therefore, even if the capacitor is short-circuited, the power supply device does not flow an overcurrent so that the power supply device does not overheat. That is, even if an internal element of the power supply apparatus is short-circuited for a long time, the power supply apparatus is not damaged.

1 is a view showing an equivalent circuit of a conventional power supply device.
2 is a view illustrating a power supply apparatus according to an embodiment of the present invention.
3 is a diagram illustrating a short-circuit detection unit of a power supply apparatus according to an embodiment of the present invention.
FIG. 4 is a diagram showing an internal signal of the power supply in a normal state, and FIGS. 5 and 6 are diagrams showing a power supply and its internal signal in a short-circuited state.
FIG. 7 is a view showing a display device including a power supply device according to an embodiment of the present invention, and FIG. 8 is a view showing pixels shown in FIG.

Hereinafter, a power supply apparatus according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

2 is a view illustrating a power supply apparatus according to an embodiment of the present invention.

2, the power supply 400 according to the embodiment of the present invention includes a power generator 430, a short-circuit detector 410, and a switch controller 420.

The power generating unit 430 may include an inductor L, a capacitor C, and a plurality of switches Tr1 and Tr2.

The inductor L is connected between an input terminal to which the input voltage Vin is applied and the first node N1 and stores a voltage corresponding to a change amount of the current input from the input voltage Vin.

The first switch Tr1 has a source electrode connected to the ground terminal, a drain electrode connected to the first node N1, a gate electrode connected to the switch control unit 420 and receiving the first control signal G1 Transistor. The arrangement relationship of the transistors is described as an NMOS in which channels are formed by electrons, but the present invention is not limited thereto.

The first switch Tr1 receives the first control signal G1 of the square wave applied from the switch control unit 420 and electrically short-circuits and opens the first node N1 to the ground terminal. The operation of the first switch Tr1 changes the intensity of the current applied to the inductor L and increases or decreases the voltage applied to the inductor L according to the change in the amount of current.

The second switch Tr2 has a source electrode connected to the first node N1 and a drain electrode connected to the output terminal N2 and a gate electrode connected to the switch control unit 420 to apply the second control signal G2 Lt; / RTI > The arrangement relationship of the transistors is described as a PMOS in which a channel is formed by holes, but the present invention is not limited thereto.

The second switch Tr2 receives the second control signal G2 of the square wave applied from the switch control unit 420 and rectifies the voltage supplied from the inductor L and outputs the rectified voltage. That is, the second switch Tr2 is a backflow preventing switch that prevents current from flowing from the output terminal N2 to the first node N1, and allows the voltage supplied from the inductor L to be supplied to the output terminal N2. Here, the second control signal G2 may be a square wave signal having a phase opposite to that of the first control signal G1.

The operation of the first switch Tr1 and the second switch Tr2 will be described later in more detail.

The capacitor C charges the voltage supplied from the inductor L due to the operation of the first switch Tr1 and the second switch Tr2 or charges the charged voltage to the output terminal N2 with the drive voltage VDD Output.

3 is a diagram illustrating a short-circuit detection unit of a power supply apparatus according to an embodiment of the present invention.

The short-circuit detection unit 410 determines whether the capacitor C is short-circuited, and outputs a short-circuit signal S to the switch control unit 420 according to whether the capacitor C is short-circuited.

The short-circuit detection unit 410 determines whether the capacitor C is short-circuited by comparing the voltage at the output terminal N2 with the short-circuit reference voltage Vref. 3, the short-circuit detection unit 410 receives the short-circuit reference voltage Vref and the driving voltage VDD applied to the output terminal N2 at its input terminal and outputs a short-circuit signal S at its output terminal. And a comparator 411 that compares the output of the comparator 411 with the reference voltage. Here, the driving voltage VDD applied to the input terminal is divided by the first resistor R1 and the second resistor R2 so that a voltage lower than the driving voltage VDD may be applied.

For example, when the driving voltage VDD is higher than the short-circuit reference voltage Vref, that is, when the capacitor C is not short-circuited, the short-circuit detection unit 410 outputs a short- And outputs a short-circuiting signal S of a high level when the driving voltage VDD is lower than the short-circuit reference voltage Vref, that is, when the capacitor C is short-circuited.

The switch control unit 420 outputs the first control signal G1 and the second control signal G2 for controlling the first switch Tr1 and the second switch Tr2 and outputs the first control signal G1 and the second control signal G2 to the operation of the power generating unit 430 So as to output the driving voltage VDD. Here, the switch control unit 420 operates differently according to the short-circuit signal S outputted at a different level depending on whether the capacitor C is short-circuited.

More specifically, the switch control unit 420 receives the low-level short-circuit signal S in a normal state in which the capacitor C is not short-circuited, outputs the low-level first control signal G1 to the first switch Tr1 and turns off the second switch Tr2 by outputting the second control signal G2 of high level. After a predetermined period of time, the switch controller 420 outputs a square-wave-shaped first control signal G1 to repeatedly switch the first switch Tr1, and outputs a square wave signal having a phase opposite to that of the first control signal G1. 2 control signal G2 to switch the second switch Tr2 repeatedly.

On the other hand, when the capacitor C is short-circuited, the switch control unit 420 receives the short-circuiting signal S of high level and outputs the low-level first control signal G1 to the first switch Tr1, And turns off the second switch Tr2 by outputting the second control signal G2 of low level. The detailed operation will be described later.

Hereinafter, an operation method of the power supply apparatus according to the embodiment of the present invention will be described.

FIG. 4 is a diagram showing an internal signal of the power supply in a normal state, and FIGS. 5 and 6 are diagrams showing the power supply and its internal signal in a short-circuited state.

2, in a normal state in which the capacitor C is not short-circuited, the driving voltage VDD of the output stage N2 is higher than the short-circuit reference voltage Vref. Therefore, as shown in FIG. 4, the short-circuit detection unit 410 outputs the low-level short-circuit signal S to the switch control unit 410.

The switch control unit 410 receiving the short-circuit signal S outputs the first control signal G1 and the second control signal G2 in a first period T1 and a second period T2, , Thereby controlling the first switch Tr1 and the second switch Tr2.

More specifically, the first section T1 is a section for pre-charging the driving voltage VDD. The first control signal G1 is applied to turn off the first switch Tr1 the second switch Tr2 is turned on by applying the second control signal G2 at the high level and the input voltage Vin at the input terminal is output as the drive voltage VDD at the output terminal N2 . Here, the input voltage Vin at the input terminal may be raised to a certain level to approach the level of the driving voltage VDD. Accordingly, the driving voltage VDD can also be raised to a certain level according to the input voltage Vin.

Then, in the second section T2, the first control signal G1 and the second control signal G2 in the form of a square wave having phases that are opposite to each other and having a constant frequency are outputted. In such a case, the operation of the first switch Tr1 and the operation of the second switch Tr2 are opposite to each other. Due to this, the output terminal N2 can not be connected to the ground terminal through the first switch Tr1 and the second switch Tr2. Therefore, it is possible to prevent the reverse current from flowing at the output terminal N2, so that the driving voltage VDD can be output at a desired level. Therefore, the drive voltage VDD can reach a desired level by the current change of the inductor L due to the switching operation of the first switch Tr1.

On the other hand, as shown in FIG. 5, the driving voltage VDD of the output terminal N2 is lower than the short circuit reference voltage Vref in a short-circuited state in which both ends of the capacitor C are short-circuited. Therefore, as shown in FIG. 6, the short-circuit detection unit 410 outputs the high-level short-circuit signal S to the switch control unit 410 from the short-circuit detection time ts.

The switch control unit 410 receiving the high level shorting signal S outputs the low level first control signal G1 and the low level second control signal G2 from the short detection time ts , The first switch Tr1 and the second switch Tr2 are all turned off. Thus, the output terminal N2 is directly connected to the ground terminal, and the driving voltage VDD is converged to the ground voltage. Therefore, a potential difference is generated in the power supply device 400, and a path through which an overcurrent flows can be prevented. Therefore, even if the capacitor C is short-circuited, the power supply device 400 does not overcurrent and the internal elements of the power supply device 400 are not overheated. That is, even if the internal elements of the power supply apparatus 400 are short-circuited for a long time, the power supply apparatus 400 is not damaged.

FIG. 7 is a view showing a display device including a power supply device according to an embodiment of the present invention, and FIG. 8 is a view showing pixels shown in FIG.

Referring to FIG. 7, a display device according to an exemplary embodiment of the present invention includes a display panel 200, a panel driver 300, and a power supply 400.

The display panel 200 includes a plurality of pixels P formed in regions defined by intersections of a plurality of data lines DL1 to DLj and a plurality of gate lines GL1 to GLk.

Each pixel P includes a light emitting element OLED and a pixel circuit 210, as shown in Fig.

The light emitting device OLED is formed between the pixel circuit 210 and the driving voltage line PL to which the driving voltage VDD is supplied from the power supply device 400 and is driven by the driving voltage line PL).

The light emitting device OLED includes an anode terminal connected to the driving voltage line PL, a cathode terminal connected to the pixel circuit 210, and a light emitting cell formed between the anode terminal and the cathode terminal to include a fluorescent material . The light emitting device OLED emits light by electrically exciting the fluorescent material according to the current (i) flowing from the anode terminal to the cathode terminal.

The pixel circuit 210 outputs a current i flowing from the driving voltage line PL to the ground power line VL via the light emitting device OLED in response to the gate voltage supplied from the panel driver 300 . To this end, the pixel circuit 210 includes a switching transistor ST, a driving transistor DT, and a storage capacitor Cst.

The switching transistor ST is switched in accordance with the gate voltage supplied to the gate line GL to supply the data voltage VData supplied to the data line DL to the driving transistor DT. Here, the switching transistor ST includes a gate electrode connected to the gate line GL, a source electrode connected to the data line DL, and a drain electrode commonly connected to the driving transistor DT and the storage capacitor Cst Film transistors.

The driving transistor DT is switched in accordance with the data voltage VData supplied from the switching transistor ST and supplies a current i flowing from the driving voltage line PL to the ground power line VL through the light emitting element OLED . Here, the driving transistor DT includes a gate electrode connected to the drain electrode of the switching transistor ST, a drain electrode connected to the cathode terminal of the light emitting element OLED, and a source electrode connected to the ground power line VL May be a thin film transistor.

The storage capacitor Cst is connected between the gate electrode of the driving transistor DT and the ground power supply line VL to store a voltage corresponding to the data voltage VData supplied to the gate electrode of the driving transistor DT, The ON state of the driving transistor DT is maintained constant for one frame.

Although the pixel circuit 210 described above is composed of two transistors ST and DT and one storage capacitor Cst, the present invention is not limited thereto. (Not shown) and at least one compensating capacitor (not shown), and may be connected between the driving transistor DT and the light emitting device OLED, And a light emission control transistor (not shown) which is switched according to a light emission control signal supplied from a light emission control signal line (not shown).

The light emitting element OLED of each pixel P is switched according to the data voltage supplied from the data line DL through the switching transistor ST switched by the gate voltage supplied to the gate line GL A predetermined image is displayed by emitting light corresponding to the intensity of the current (i) output by the driving transistor DT. At this time, the current i flowing in the light emitting element OLED is changed according to the voltage Vgs between the gate and source of the driving transistor DT, the threshold voltage Vth of the driving transistor DT, and the data voltage VData .

7, the panel driver 300 includes a timing controller 310, a data driver 320, and a gate driver 330.

The timing controller 310 aligns the input data signals RGB to be displayed on the display panel 200 and supplies the data signals R, G, and B to the data driver 320. The timing control unit 310 generates a timing control signal for controlling the driving timing of the data driving unit 320 and the gate driving unit 330 using the input timing synchronization signal TSS and supplies the timing control signal to the data driving unit 320 and the gate Driving unit 330, respectively. Here, the timing synchronization signal TSS is a vertical synchronization signal Vsync; A horizontal synchronizing signal Hsync; A data enable signal (Data Enable); And a dot clock (DCLK). The timing control signals include a data control signal DCS for supplying a data voltage to the data line DL of the display panel 200; And a gate control signal GCS for truncating the gate line GL of the display panel 200. [

The data driver 320 receives a data voltage for one horizontal line corresponding to the data signals R, G, and B supplied from the timing controller 310 according to a data control signal DCS supplied from the timing controller 310 And supplies the generated data voltages for one horizontal line to each pixel P through each of the data lines DL1 to DLj.

The gate driver 330 generates a gate voltage according to the scan control signal SCS supplied from the timing controller 310 and sequentially outputs the generated gate voltage to the gate lines GL1 to GLk.

 The power supply device 400 generates a driving voltage VDD and supplies the generated driving voltage VDD to the driving voltage line PL formed on the display panel 200 to be supplied to each pixel P. For this, the power supply device 400 is configured in the same manner as the power supply device 400 shown in FIGS. 2 to 6, and a detailed description thereof will be given below with reference to FIG. 2 to FIG. 400) will be described instead.

Meanwhile, in the display device according to the embodiment of the present invention, a light emitting diode display device including a display panel 200 having a light emitting element that emits light by current is described as an example. However, the present invention is not limited to this, A flat panel display device configured to include a display panel 400.

While a number of embodiments have been described in detail above, it should be construed as being illustrative of preferred embodiments rather than limiting the scope of the invention. Therefore, the invention should not be construed as limited to the embodiments described, but should be determined by equivalents to the appended claims and the claims.

100: display device 200: display panel
300: panel driver 400: power supply
410: short detection unit 420: switch control unit
430: Power generator

Claims (9)

A power generating unit converting a voltage input to an input terminal into a driving voltage and outputting the input voltage to an output terminal using a plurality of switches;
A short-circuit detection unit for determining whether the output terminal is short-circuited and generating a short-circuit signal; And
And a switch control unit for controlling the plurality of switches according to the short-circuit signal. The method according to claim 1,
The power generating unit
An inductor connected between the input terminal and the first node;
A first switch connected between the first node and a ground terminal;
A second switch connected between the first node and the output terminal; And
And a capacitor connected between the output terminal and the ground terminal. 3. The method of claim 2,
Wherein the first switch is a transistor controlled according to a first control signal output from the switch control unit,
And the second switch is a transistor controlled according to a second control signal output from the switch control unit. 3. The method of claim 2,
The short-
And compares the driving voltage outputted to the output terminal with a short circuit reference voltage to judge whether the short circuit is short-circuited. 5. The method of claim 4,
The short-
When the short-circuit reference voltage is higher than the driving voltage, a short-
And outputs a low-level short-circuit signal when the short-circuit reference voltage is lower than the driving voltage. 6. The method of claim 5,
The switch control unit
When the high-level short-circuit signal is applied,
And outputs a first control signal of a low level and a second control signal of a low level to turn off both the first switch and the second switch. 6. The method of claim 5,
The switch control unit
When the low-level short-circuit signal is applied,
And outputs a first control signal of a low level and a second control signal of a high level in a first section to turn off the first switch and turn on the second switch. 8. The method of claim 7,
The switch control unit
When the low-level short-circuit signal is applied,
And outputs a first control signal and a second control signal in the form of a rectangular wave whose phases are opposite to each other in a second section continuous to the first section to alternately turn on and off the first switch and the second switch Power supply. A display panel including a plurality of pixels;
And a power supply for outputting a driving voltage applied to the display panel,
The power supply
A power generating unit converting a voltage input to an input terminal into a driving voltage and outputting the input voltage to an output terminal using a plurality of switches;
A short-circuit detection unit for determining whether the output terminal is short-circuited and generating a short-circuit signal; And
And a switch controller for controlling the plurality of switches according to the short-circuit signal,
Wherein the pixel includes a light emitting element that is connected between the driving voltage and the ground power supply and emits light by a current flowing therethrough.

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