KR20120023252A - Apparatus for supplying power, back light unit and display apparatus using the same - Google Patents

Abstract

PURPOSE: A power supply device, a backlight unit using the same, and a display device are provided to improve efficiency by reducing a switching loss of a switching device. CONSTITUTION: A boost inductor(Lb) is connected to an input power source and a first node. A first diode is connected between the first node and an output node. A switching device(S) is connected between a second node and a base power source. A second diode is connected between the second node and a third node. A capacitor is connected between the third node and the base power source. A transformer includes a primary coil and a secondary coil. The primary coil is connected between the first node and the second node. The secondary coil is connected between the output node and the third node.

Description

Power supply unit, backlight unit and display device using the same {APPARATUS FOR SUPPLYING POWER, BACK LIGHT UNIT AND DISPLAY APPARATUS USING THE SAME}

The present invention relates to a power supply device, and more particularly, to a power supply device, a backlight unit, and a display device using the same to reduce the switching loss of the switching element to improve the efficiency.

In general, a power supply device rectifies and converts a DC voltage into an AC voltage, boosts or steps down a DC voltage to a required voltage, and provides the same to various devices (eg, display devices).

1 is a view schematically showing a conventional power supply device.

Referring to FIG. 1, a conventional power supply device is a step-up converter, and includes a booster inductor Lb, a diode D, a capacitor C, and a switching device S. The boost converter boosts the input voltage Vin by outputting energy stored in the booster inductor Lb through the diode D according to the switching of the switching element S. FIG.

However, in the conventional boost converter, as shown in FIG. 2, when the switching element S is turned on, since the switching element S performs hard switching, the switch voltage V Switching loss SL due to a region where _S ) and the switch current I _S cross each other may cause a problem in that efficiency may be lowered. In addition, since the switching loss is proportional to the switching frequency of the switching device S, when the switching frequency is increased, the switching loss also increases.

In addition, the conventional boost converter has a problem that the switching loss is generated by the transient current and the input current due to the reverse recovery characteristic of the diode D, and the efficiency is lowered.

As a result, the conventional boost converter has a problem in that the efficiency is lowered due to the switching loss SL due to the hard switching of the switching element S and the switching loss due to the reverse recovery characteristic of the diode D.

Recently, in order to meet the trend toward higher density and miniaturization of power supply devices, the switching frequency must be increased, and a method for solving the problem of efficiency degradation due to the switching loss is necessary.

Disclosure of Invention The present invention has been made in view of the above-described problems, and it is an object of the present invention to provide a power supply device, a backlight unit, and a display device using the same, capable of reducing the switching loss of a switching element to improve efficiency.

According to an aspect of the present invention, there is provided a power supply apparatus including: an input power source; A booster inductor connected between the input power source and a first node; A first diode connected between the first node and an output node; A switching element connected between the second node and the base power supply; A second diode connected between the second node and a third node; A capacitor connected between the third node and the base power source; And a transformer having a primary coil connected between the first node and the second node, and a secondary coil connected between the output node and the third node.

According to an aspect of the present invention, there is provided a power supply apparatus including: an input power source; A booster inductor connected between the input power source and a first node; A switching element connected between said first node and said base power source; A first diode connected between the second node and the output node; A second diode connected between the first node and a third node; A capacitor connected between the third node and the base power source; And a transformer having a primary coil connected between the first node and the second node, and a secondary coil connected between the output node and the third node.

According to an aspect of the present invention, there is provided a power supply device including: a booster inductor through which a current is supplied from an input power source; A switching element controlling a current flowing through the booster inductor according to switching; And forming first and second current paths between the booster inductor and the output node, and linearly increasing a current flowing through the switching device when the switching device is turned on using a transformer. And a current path forming unit configured to form at least one current path among the first and second current paths according to the switching of the switching element.

The current path forming unit includes: a first diode forming the first current path between the booster inductor and the output node; A second diode for outputting a current supplied from the primary coil of the transformer; The transformer having a primary coil linearly increasing a current supplied from the booster inductor to the switching element, and a secondary coil connected to the output node; And a capacitor charged by a current output from the second diode, wherein the secondary coil of the transformer forms the second current path between the second diode and the output node according to the voltage of the capacitor or Form a third current path between the capacitor and the output node.

The current path forming unit includes: a transformer having a primary coil linearly increasing a current supplied from the booster inductor to the switching element, and a secondary coil connected to the output node; A first diode forming the first current path between the primary coil of the transformer and the output node; A second diode outputting a current output from the booster inductor; And a capacitor charged by a current output from the second diode, wherein the secondary coil of the transformer forms the second current path between the second diode and the output node according to the voltage of the capacitor or Form a third current path between the capacitor and the output node.

According to an aspect of the present invention, there is provided a backlight unit including a driving voltage supply unit including the power supply device; At least one light emitting diode array connected in parallel to an output node of the power supply; And a duty controller configured to generate a switching control signal having a predetermined duty to control switching of the switching element configured in the power supply device.

According to an aspect of the present invention, there is provided a display apparatus including: a liquid crystal display panel configured to display a predetermined image by adjusting a light transmittance of a liquid crystal; And the backlight unit for irradiating light to the display panel.

According to an aspect of the present invention, there is provided a display apparatus including: a display panel displaying a predetermined image; And the power supply device for generating power for driving the display panel.

According to the above solution, the present invention provides the following effects.

First, by soft switching the switching element at the time of turn-on of the switching element, it is possible to reduce the switching loss caused by the region where the switch voltage and the switch current intersect, thereby improving the efficiency of the power supply.

Second, it can cope with the trend of higher density and smaller size of power supply.

1 is a view schematically showing a conventional power supply device.
2 is a waveform diagram illustrating a switching loss generated in a conventional power supply.
3 is a diagram schematically illustrating a power supply device according to a first embodiment of the present invention.
4 is a waveform diagram illustrating a switching loss of the power supply apparatus according to the first embodiment of the present invention.
5A through 5D are diagrams illustrating a driving mode of a power supply apparatus according to a first exemplary embodiment of the present invention, in stages.
6 is a waveform diagram illustrating voltage and current waveforms according to the driving modes illustrated in FIGS. 5A to 5D.
7 is a graph measuring the efficiency of the power supply apparatus according to the first embodiment of the present invention.
8 is a diagram schematically illustrating a power supply device according to a second embodiment of the present invention.
9 is a waveform diagram illustrating a switching loss of a power supply device according to a second embodiment of the present invention.
10A through 10D are diagrams illustrating a driving mode of a power supply apparatus according to a second exemplary embodiment of the present invention, in stages.
FIG. 11 is a waveform diagram illustrating voltage and current waveforms according to the driving modes illustrated in FIGS. 10A to 10D.
12 is a graph measuring the efficiency of the power supply apparatus according to the second embodiment of the present invention.
FIG. 13 is a diagram schematically illustrating a backlight unit according to an exemplary embodiment of the present invention.
14 is a diagram schematically illustrating a display device according to a first embodiment of the present invention.
FIG. 15 is a diagram schematically illustrating a display apparatus according to a second exemplary embodiment of the present invention.

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

3 is a diagram schematically illustrating a power supply device according to a first embodiment of the present invention.

Referring to FIG. 3, the power supply device 100 according to the first embodiment of the present disclosure includes an input power source Vin, a booster inductor Lb, a switching element S, and a current path forming unit 110. It is configured by.

The input power Vin generates a predetermined level of DC power and supplies it to the booster inductor Lb.

The booster inductor Lb is connected between the input power source Vin and the first node N1 and has a first terminal connected to the input power source Vin and a second terminal connected to the first node N1. do. The booster inductor Lb stores the current supplied from the input power Vin according to the switching of the switching element S, or supplies the stored current to the current path forming unit 110.

The switching element S is connected between the first node N1 and the base power source and switched according to a switching control signal having a predetermined duty from a switching controller (not shown). The switching element S is switched according to the switching control signal to control the current flowing in the booster inductor Lb. In this case, the switching element S may be a field effect transistor (FET), an insulated gate bipolar transistor (IGBT), or an integrated gate commutated thyristor (IGCT).

The current path forming unit 110 forms first and second current paths between the booster inductor Lb and the output node No, and the switching element (Turn-On) when the switching element S is turned on ( The current flowing in S) is linearly increased, and at least one current path of the first and second current paths is formed according to the switching of the switching element S.

To this end, the current path forming unit 110 is configured to include a first diode (D1), a transformer (TF), a second diode (D2), and a capacitor (C).

The first diode D1 is connected between the first node N1 and the output node No, and has an anode terminal connected to the first node N1 and a cathode terminal connected to the output node No. . The first diode D1 conducts when the voltage of the first node N1 is higher than the output node No to form a first current path between the booster inductor Lb and the output node No. When the voltage at one node N1 is lower than the output node No, it is opened to block the reverse current flowing from the output node No to the booster inductor Lb.

The transformer TF includes a primary coil connected to the first node N1 and the switch element S, and a secondary coil connected to the output node No and the third node N3.

When the switching element S is turned on from the off state to the on state, the transformer TF receives a current flowing from the booster inductor Lb to the switching element S through the primary coil. While increasing linearly, the current flowing to the first diode D1 is linearly decreased. That is, the transformer TF switches by using the inductance of the primary coil to adjust the slope of the current flowing through the switching element S at turn-on of the switching element S, as shown in FIG. 4. Allow device S to be soft switched. Accordingly, the switching element S is soft-switched at the time of turn-on of the switching element S, thereby minimizing the area where the switch voltage V _S intersects the switch current I _S , thereby switching loss SL. In addition to this reduction, the switching loss generated in the switching element S is reduced by the reverse recovery characterist of the first diode D1.

On the other hand, the secondary coil of the transformer TF is connected between the output node No and the third node N3, that is, the cathode terminals of the first and second diodes D1 and D2. The secondary coil of may form a second current path between the second diode D2 and the output node No, depending on the charge charged in the capacitor C, or the second coil between the capacitor C and the output node No. 3 Form a current path.

The second diode D2 is connected between the second node N2 and the third node N3. The second diode D2 connects an anode terminal connected to the second node N2 and a cathode terminal connected to the third node N3. Equipped. The second diode D2 outputs a current supplied from the primary coil of the transformer TF to the third node N3 when the switching element S is turned off. At this time, when the switching element S is turned off, the current output from the second diode D2 to the third node N3 gradually decreases according to the voltage of the third node N3, and the voltage of the third node N3 is reduced. It is opened when it is equal to or higher than the voltage applied to the switching element S.

The capacitor C is connected between the third node N3 and the base power supply. The capacitor C is charged by the current output from the second diode D2, and discharges the charged charge to the third node N3. In addition, the capacitor C suppresses an increase in the voltage applied to the switching element S by resonating the primary coil of the transformer TF and the parasitic capacitor of the switching element S when the switching element S is turned off.

Meanwhile, the power supply device according to the embodiment of the present invention described above may further include a smoothing capacitor Cd connected between the output node No and the base power source.

The smoothing capacitor Cd makes the power output from the current path forming unit 110 to the output node No constant. The smoothing capacitor Cd may be embedded in a load circuit connected to the output node No. Here, the load may be a light emitting diode (LED), various information devices, a display device, or the like.

5A through 5D are diagrams illustrating a driving mode of a power supply apparatus according to a first exemplary embodiment of the present invention. FIG. 6 is a waveform illustrating voltage and current waveforms according to the driving modes illustrated in FIGS. 5A through 5D. It is also.

5A to 5D will be described with reference to FIG. 6 to describe a driving method of a power supply apparatus according to a first embodiment of the present invention.

First, in the first driving mode M1, as shown in FIGS. 5A and 6, when the switching element S is turned on from an off state to an on state, the booster inductor Lb The current I _D1 flowing from the first diode D1) decreases linearly, and the current I _S flowing into the switching element S is input by the primary coil of the transformer TF. It increases linearly until it reaches the input current I _In that comes from. That is, when the switching element S starts to be turned on in the off state, the current I _D1 of the first diode D1 and the current I S of the switching element _S (or the primary coil of the transformer TF) _In the input current I _In formed by the sum of the currents I _pre flowing in the current, the current I _D1 of the first diode D1 decreases linearly and the current I of the switching element S _S ) is linearly increased by the inductance of the primary coil of the transformer TF. Accordingly, at turn-on of the switching element S, the switching element S is soft switched in accordance with the switch current I _S which increases linearly by the primary coil of the transformer TF, thereby being shown in FIG. 4. As described above, the switching loss SL generated during the switching of the switching element S is minimized.

Next, in the second driving mode M2, as shown in FIGS. 5B and 6, when the switching element S is in an on state, the first and second nodes N1 and N2 may be turned on. Since the voltage becomes the base power source, the first and second diodes D1 and D2 are opened, and the charge I _C charged in the capacitor C is transferred to the output node No through the secondary coil of the transformer TF. Is output.

Next, in the third driving mode M3, as shown in FIGS. 5C and 6, when the switching element S is hard switched quickly from the on state to the off state, the input power Vin ), A second current path leading to the booster inductor Lb, the primary coil of the transformer TF, the second diode D2, the secondary coil of the transformer TF, and the output node No is formed, and A part of the current output from the two diodes D2 is charged in the capacitor C. That is, when the switching element S is turned off, the input current I _In and the current I _Lb stored in the booster inductor Lb flow through the second diode D2 to the output node No. In this case, the current I _D2 flowing in the second diode D2 is the current I _sec flowing through the secondary coil of the third node N3 and the transformer TF to the output node No and the third node ( It is divided into the current I _C which charges the capacitor C through N3).

In addition, since the switching element S is in an off state, the voltage of the first node N1 increases to the voltage of the output node No.

Next, in the fourth driving mode M4, as shown in FIGS. 5D and 6, when the off state of the switching element S is maintained, the charge charged in the capacitor C is maintained in the third node N3. And is outputted to the output node No through the secondary coil of the transformer TF, and as the current flowing in the second diode D2 decreases due to the discharge of the capacitor C, the first diode D1 is turned on. A first current path is formed that leads to the booster inductor Lb, the first diode D1, and the output node No. That is, when the switching element S maintains the off state, when the voltage of the capacitor C charged by the current I _D2 flowing in the second diode D2 becomes higher than the voltage of the output node No, the capacitor (C) discharges the charged charge (I _C ) to the output node (No) through the secondary coil of the third node (N3) and transformer (TF), so that the voltage of the third node (N3) is the capacitor (C) It rises by the current I _C discharged from and becomes equal to the switch voltage V _S applied to the switching element S. FIG. Accordingly, as the voltage of the third node N3 increases and the current I _D2 flowing in the second diode D2 gradually decreases, the current I _pre flowing in the primary coil of the transformer TF also decreases gradually. Done. On the other hand, when the voltage of the first node N1 gradually increases and becomes higher than the voltage of the output node No, the first diode D1 is conducted, so that the booster inductor Lb, the first diode D1, and the output node are conducted. A first current path leading to (No) is formed.

The first to fourth driving modes M1 to M4 have been described by dividing the operation of one cycle of the switching control signal. The power supply device 100 according to the first embodiment of the present invention may include the above-described first operation. By repeatedly performing the operations corresponding to the fourth to fourth driving modes M1 to M4, constant power is output to the output node No.

7 is a graph measuring the efficiency of the power supply apparatus according to the first embodiment of the present invention.

As shown in FIG. 7, it can be seen that the efficiency (○) of the power supply device 100 according to the first embodiment of the present invention represents an improved 93.1 to 94.7% compared to the conventional (□). As can be seen from the experimental results, the power supply device 100 according to the first embodiment of the present invention, as shown in Figure 4, the current path forming unit 110 during the turn-on of the switching element (S) That is, the switch voltage V _S and the switch current I _S intersect by linearly increasing the current flowing through the primary coil of the transformer TF and switching the switching element S so as to soft switch the switching element S. Minimize the area. Therefore, the power supply device 100 according to the first embodiment of the present invention reduces the switching loss of the switching element S at turn-on of the switching element S, thereby minimizing the reduction in efficiency due to the switching loss. It can provide improved efficiency.

8 is a diagram schematically illustrating a power supply device according to a second embodiment of the present invention.

Referring to FIG. 8, the power supply device 200 according to the second embodiment of the present invention includes an input power source Vin, a booster inductor Lb, a switching element S, and a current path forming unit 210. It is configured by.

The input power Vin generates a predetermined level of DC power and supplies it to the booster inductor Lb.

The booster inductor Lb is connected between the input power source Vin and the first node N1 and has a first terminal connected to the input power source Vin and a second terminal connected to the first node N1. do. The booster inductor Lb stores the current supplied from the input power Vin according to the switching of the switching element S, or supplies the stored current to the current path forming unit 210.

The switching element S is connected between the first node N1 and the base power source and switched according to a switching control signal having a predetermined duty from a switching controller (not shown). The switching element S is switched according to the switching control signal to control the current flowing in the booster inductor Lb. In this case, the switching element S may be a field effect transistor (FET), an insulated gate bipolar transistor (IGBT), or an integrated gate rectifier thyristor (IGCT).

The current path forming unit 210 forms first and second current paths between the booster inductor Lb and the output node No, and switches the switching element at turn-on of the switching element S. The current flowing in S) is linearly increased, and at least one current path of the first and second current paths is formed according to the switching of the switching element S.

To this end, the current path forming unit 210 includes a transformer (TF), a first diode (D1), a second diode (D2), and a capacitor (C).

The transformer TF is composed of a primary coil connected to the anode of the first node N1 and the first diode D1, and a secondary coil connected to the output node No and the third node N3.

The transformer TF linearly increases the current flowing from the booster inductor Lb to the switching element S when the switching element S is turned on from the off state to the on state. On the other hand, the current flowing to the first diode D1 through the primary coil is linearly reduced. That is, the transformer TF adjusts the slope of the current flowing through the switching element S at the time of turn-on of the switching element S by using the inductance of the primary coil, as shown in FIG. 9, the switching element S ) Is soft switched. Accordingly, when the switching element S is turned on, the switching element S is soft switched, thereby minimizing an area where the switch voltage V _S intersects the switch current I _S , thereby reducing the switching loss SL. In addition, the switching loss generated in the switching element S is reduced by the reverse recovery characteristic of the first diode D1.

Meanwhile, the secondary coil of the transformer TF is connected between the output node No and the third node N3, that is, the cathode terminals of the first and second diodes D1 and D2. The secondary coil of may form a second current path between the second diode D2 and the output node No or, depending on the charge charged in the capacitor C, or between the capacitor C and the output node No. 3 Form a current path.

The first diode D1 is connected between the output node No and the second node N2 connected to one side of the primary coil of the transformer TF, and the output of the anode terminal connected to the second node N2 A cathode terminal connected to the node No is provided. The first diode D1 is turned on when the voltage of the second node N2 is higher than the output node No to form a first current path between the booster inductor Lb and the output node No. When the voltage at the two nodes N2 is lower than the output node No, the voltage is opened to block the reverse current flowing from the output node No to the booster inductor Lb.

The second diode D2 is connected between the first node N1 and the third node N3. The second diode D2 connects an anode terminal connected to the first node N1 and a cathode terminal connected to the third node N3. Equipped. The second diode D2 outputs a current supplied from the booster inductor Lb to the third node N3 when the switching element S is turned off. At this time, when the switching element S is turned off, the current output from the second diode D2 to the third node N3 gradually decreases according to the voltage of the third node N3, and the voltage of the third node N3 is reduced. It is opened when it is equal to or higher than the voltage applied to the switching element S.

The capacitor C is connected between the third node N3 and the base power supply. The capacitor C is charged by the current output from the second diode D2, and discharges the charged charge to the third node N3. In addition, the capacitor C suppresses an increase in the voltage applied to the switching element S by resonating the primary coil of the transformer TF and the parasitic capacitor of the switching element S when the switching element S is turned off.

Meanwhile, the power supply device according to the embodiment of the present invention described above may further include a smoothing capacitor Cd connected between the output node No and the base power source.

The smoothing capacitor Cd makes the power output from the current path forming unit 210 to the output node No constant. The smoothing capacitor Cd may be embedded in a load circuit connected to the output node No.

10A to 10D are diagrams illustrating a driving mode of a power supply device according to a second embodiment of the present invention, and FIG. 11 is a waveform illustrating voltage and current waveforms according to the driving modes shown in FIGS. 10A to 10D. It is also.

A driving method of the power supply apparatus according to the second embodiment of the present invention will be described with reference to FIGS. 10A to 10D as follows.

First, in the first driving mode M1, as shown in FIGS. 10A and 11, when the switching element S is turned on from an off state to an on state, the booster inductor Lb The current I _D1 flowing from) to the first diode D1 is linearly reduced by the primary coil of the transformer TF, and the current I _S flowing into the switching element _S is input power Vin. It increases linearly until it reaches the input current I _In that comes from. That is, when the switching element S starts to be turned on in the off state, the current I _D1 of the first diode _D1 (or the current I _pre flowing through the primary coil of the transformer TF) and the switching element ( _In the input current I _In formed by the sum of the current I _S of _S ), the current I _D1 of the first diode D1 decreases linearly by the inductance of the primary coil. In turn, the current I _S of the switching element S increases linearly. Accordingly, the slope of the current I _S flowing in the switching element S at the time of turn-on of the switching element S is adjusted to increase linearly by the primary coil of the transformer TF, thereby as shown in FIG. 9. As described above, the switching loss SL generated during the switching of the switching element S is minimized.

Next, in the second driving mode M2, as shown in FIGS. 10B and 11, when the switching element S is in an on state, the voltage of the first node N1 may be reduced. Therefore, the first and second diodes D1 and D2 are opened, and the charge charged in the capacitor C is output to the output node No through the secondary coil of the transformer TF.

Next, in the third driving mode M3, as shown in FIGS. 10C and 11, when the switching element S is hard switched quickly from the on state to the off state, the input power Vin and the booster inductor A second current path is formed which leads to Lb, the second diode D2, the secondary coil of the transformer TF, and the output node No, and a part of the current output from the second diode D2 is a capacitor. (C) is charged. That is, when the switching element S is turned off, the input current I _In and the current I _Lb stored in the booster inductor Lb flow through the second diode D2 to the output node No. In this case, the current I _D2 flowing in the second diode D2 is the current I _sec flowing through the secondary coil of the third node N3 and the transformer TF to the output node No and the third node ( It is divided into the current I _C which charges the capacitor C through N3).

In addition, since the switching element S is in an off state, the voltage of the second node N2 increases to the voltage of the output node No.

Next, in the fourth driving mode M4, as shown in FIGS. 10D and 11, when the off state of the switching element S is maintained, the charge charged in the capacitor C is transferred to the third node N3. And is outputted to the output node No through the secondary coil of the transformer TF, and as the current flowing in the second diode D2 decreases due to the discharge of the capacitor C, the first diode D1 is turned on. A first current path is formed that leads to the booster inductor Lb, the primary coil of the transformer TF, the first diode D1, and the output node No. That is, when the switching element S maintains the off state, when the charging voltage of the capacitor C due to the current I _D2 flowing in the second diode D2 becomes higher than the output node No, the capacitor C Is discharged to the output node No through the secondary coil of the third node N3 and the transformer TF, so that the voltage of the third node N3 is discharged from the capacitor _C. To rise. Accordingly, as the voltage of the third node N3 is increased and the current I _D2 flowing in the second diode D2 gradually decreases, the current I _pre flowing in the primary coil of the transformer TF gradually increases. Done. Accordingly, when the voltage of the second node N2 gradually increases and becomes higher than the voltage of the output node No, the first diode D1 is turned on so that the booster inductor Lb, the primary coil of the transformer TF, A first current path is formed which leads to one diode D1 and an output node No.

The above-described first to fourth driving modes M1 to M4 are divided and described for one cycle of the switching control signal, and according to the second embodiment of the present invention, the power supply device 200 according to the first embodiment is described above. By repeatedly performing the operations corresponding to the fourth to fourth driving modes M1 to M4, constant power is output to the output node No.

12 is a graph measuring the efficiency of the power supply apparatus according to the second embodiment of the present invention.

As shown in FIG. 12, it can be seen that the efficiency (●) of the power supply device 200 according to the second embodiment of the present invention represents 94.6 to 95% improved compared to the conventional (■). As can be seen from the experimental results, the power supply device 200 according to the second embodiment of the present invention, as shown in FIG. 9, the current path forming unit 210 at the turn-on of the switching element (S) That is, a region in which the switch voltage V _S and the switch current I _S cross each other by softly switching the switching element S by linearly increasing the current flowing through the switching element S through the inductance of the transformer TF. Minimize. Therefore, the power supply device 200 according to the second embodiment of the present invention reduces the switching loss of the switching element S when the switching element S is turned on, thereby minimizing the reduction in efficiency due to the switching loss. It can provide improved efficiency.

FIG. 13 is a diagram schematically illustrating a backlight unit according to an exemplary embodiment of the present invention.

Referring to FIG. 13, the backlight unit 300 according to an embodiment of the present invention includes a driving voltage supply unit 310, a plurality of light emitting diode arrays LA1 to LAn, and a duty controller 320.

The driving voltage supply unit 310 generates driving voltages required for driving the plurality of light emitting diode arrays LA1 to LAn under the control of the duty controller 320 using the input power Vin supplied from the outside, and generated. The driving voltage is supplied to the plurality of light emitting diode arrays LA1 to LAn. To this end, the driving voltage supply unit 310 is a power supply device 100 according to the first embodiment of the present invention shown in FIG. 3 or a power supply device 200 according to the second embodiment of the present invention shown in FIG. It is configured to include). Hereinafter, the description of the power supply apparatuses 100 and 200 will be replaced with the above description of FIGS. 3 to 12.

Each of the plurality of light emitting diode arrays LA1 to LAn is electrically connected in parallel to a driving voltage supply unit 310, that is, an output node No (see FIG. 3 or FIG. 8) of the power supply devices 100 and 200. Each of the plurality of light emitting diode arrays LA1 to LAn includes a plurality of light emitting diodes LED electrically connected in series between an output node No of the power supply devices 100 and 200 and a base power source.

The duty controller 320 generates a switching control signal SCS having a predetermined duty to control switching of the switching elements S (see FIG. 3 or FIG. 8) of the power supplies 100 and 200.

On the other hand, the duty controller 320 detects the current flowing through the plurality of light emitting diode arrays LA1 to LAn and controls the duty of the switching control signal SCS to set a current flowing through the plurality of light emitting diode arrays LA1 to LAn. Control.

As such, the backlight unit 300 according to the exemplary embodiment of the present invention controls the switching of the switching element S provided in the driving voltage supply unit 310 to provide a constant driving voltage to the plurality of light emitting diode arrays LA1 to LAn. By supplying Vd, each light emitting diode LED of the plurality of light emitting diode arrays LA1 to LAn emits light to generate light having a predetermined brightness.

14 is a diagram schematically illustrating a display device according to a first embodiment of the present invention.

Referring to FIG. 14, the display device according to the first embodiment of the present invention includes a display panel 400, a panel driver 500, and a power supply 600.

The display panel 400 displays an image corresponding to the input data R, G, and B supplied according to the driving of the panel driver 500. In this case, the display panel 400 may be a liquid crystal display panel, an organic light emitting display panel, a field emission display panel, or a plasma display panel. It may be a display panel of a digital display device including the.

The panel driver 500 displays an image corresponding to the input data RGB input from the outside on the display panel 400. To this end, the panel driver 500 includes a timing controller 510, a data driver circuit 520, and a scan driver circuit 530.

The timing controller 510 arranges the input data RGB input from the outside to be suitable for driving the display panel 200 and supplies the input data RGB to the data driver circuit 520.

In addition, the timing controller 510 may include a vertical synchronization signal Vsync; Horizontal synchronization signal (Hsync); A data enable signal; And a data control signal DDS and a scan control signal for controlling the operation timing of the data driving circuit unit 520 and the scan driving circuit unit 530 using the timing synchronization signal TSS including the dot clock DCLK and the like. SDS).

The data driving circuit unit 520 latches the data signals R, G, and B input from the timing controller 510 according to the data control signal DDS supplied from the timing controller 510, and converts the latched data signals into analog. The pixel voltage is converted to the pixel voltage and supplied to the data lines DL.

The scan driving circuit unit 530 generates scan pulses according to the scan control signal SDS supplied from the timing controller 510 and sequentially supplies the scan pulses to the scan lines SL.

The power supply unit 600 generates a driving voltage for driving the display panel 400 and the panel driver 500 by using input power supplied from the outside. To this end, the power supply unit 600 is a power supply device 100 according to the first embodiment of the present invention shown in FIG. 3 or a power supply device 200 according to the second embodiment of the present invention shown in FIG. It is configured to include. Hereinafter, the description of the power supply apparatuses 100 and 200 will be replaced with the above description of FIGS. 3 to 12.

FIG. 15 is a diagram schematically illustrating a display apparatus according to a second exemplary embodiment of the present invention.

Referring to FIG. 15, the display device according to the second embodiment of the present invention includes a liquid crystal display panel 700, a panel driver 800, a backlight unit 300, and a power supply 900.

The liquid crystal display panel 700 includes a plurality of pixels P formed for each region defined by the plurality of gate lines GL and the plurality of data lines DL.

Each of the plurality of pixels P includes a thin film transistor (not shown) connected to the gate line GL and the data line DL, and a liquid crystal cell connected to the thin film transistor.

The liquid crystal display panel 700 displays a predetermined image by forming an electric field in the liquid crystal cell according to the pixel voltage supplied to each pixel P to adjust the transmittance of light emitted from the backlight unit 300.

The panel driver 800 displays an image corresponding to the input data RGB input from the outside on the liquid crystal display panel 700. To this end, the panel driver 800 includes a timing controller 810, a data driver circuit 820, and a gate driver circuit 830.

The timing controller 810 arranges the input data RGB input from the outside to be suitable for driving the liquid crystal display panel 700 and supplies the input data RGB to the data driver circuit 820.

In addition, the timing controller 810 controls the operation timing of the data driver circuit 820 and the gate driver circuit 830 by using the input timing synchronization signal TSS. GCS).

The timing synchronization signal TSS is a vertical synchronization signal Vsync; Horizontal synchronization signal (Hsync); A data enable signal; And a dot clock DCLK.

The data control signal DCS includes a source start pulse; A source sampling clock; Source Output Enable; And a polarity control signal POL.

The gate control signal GCS may include a gate start pulse; Gate Shift Clock; And a gate output enable.

The data driving circuit unit 820 latches the data signals R, G, and B input from the timing control unit 810 according to the data control signal DCS supplied from the timing control unit 810, and performs analog positive / negative polarity. After the latched data signal is converted to the positive / negative analog pixel voltage using the gamma voltage, a pixel voltage having a polarity corresponding to the polarity control signal is generated and supplied to the data lines DL.

The gate driving circuit unit 830 generates gate pulses according to the gate control signal GCS supplied from the timing controller 810 and sequentially supplies the gate pulses to the gate lines GL.

The backlight unit 300 irradiates light to the liquid crystal display panel 700 using a light emitting diode (LED). To this end, since the backlight unit 300 is configured to include a backlight unit according to an embodiment of the present invention shown in FIG. 13, a description thereof will be replaced with the above description.

Meanwhile, the backlight unit 300 may further include a plurality of optical members for improving luminance characteristics of light emitted from the plurality of light emitting diode arrays described above.

The power supply unit 900 generates driving voltages required to drive the liquid crystal display panel 700 and the panel driver 800 using input power supplied from the outside. To this end, the power supply unit 900 is a power supply device 100 according to the first embodiment of the present invention shown in FIG. 3 or a power supply device 200 according to the second embodiment of the present invention shown in FIG. It is configured to include. Hereinafter, the description of the power supply apparatuses 100 and 200 will be replaced with the above description of FIGS. 3 to 12.

Those skilled in the art to which the present invention pertains will understand that the present invention can be implemented in other specific forms without changing the technical spirit or essential features. Therefore, it is to be understood that the embodiments described above are exemplary in all respects and not restrictive. The scope of the present invention is shown by the following claims rather than the detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalent concepts should be construed as being included in the scope of the present invention. do.

100, 200: power supply unit 110, 210: current path forming unit
300: backlight unit 310: driving voltage supply unit
320: duty controller 400: display panel
500, 800: panel driver 700: liquid crystal display panel

Claims (17)

Input power;
A booster inductor connected between the input power source and a first node;
A first diode connected between the first node and an output node;
A switching element connected between the second node and the base power supply;
A second diode connected between the second node and a third node;
A capacitor connected between the third node and the base power source; And
And a transformer having a primary coil connected between the first node and the second node, and a secondary coil connected between the output node and the third node. Input power;
A booster inductor connected between the input power source and a first node;
A switching element connected between said first node and said base power source;
A first diode connected between the second node and the output node;
A second diode connected between the first node and a third node;
A capacitor connected between the third node and the base power source; And
And a transformer having a primary coil connected between the first node and the second node, and a secondary coil connected between the output node and the third node. A booster inductor through which current is supplied from an input power source;
A switching element controlling a current flowing through the booster inductor according to switching; And
Forming first and second current paths between the booster inductor and the output node, linearly increasing a current flowing through the switching element when the switching element is turned on using a transformer, and And a current path forming unit for forming at least one current path among the first and second current paths according to the switching of the switching element. The method of claim 3, wherein
The transformer is a power supply characterized in that it comprises a primary coil and a secondary coil having a turns ratio of 1: 1. The method of claim 3, wherein
The current path forming unit,
A first diode forming the first current path between the booster inductor and the output node;
A second diode for outputting a current supplied from the primary coil of the transformer;
The transformer having a primary coil linearly increasing a current supplied from the booster inductor to the switching element, and a secondary coil connected to the output node; And
A capacitor charged by a current output from the second diode,
The secondary coil of the transformer forms the second current path between the second diode and the output node or a third current path between the capacitor and the output node according to the voltage of the capacitor. Power supply. The method of claim 5, wherein
In a first driving mode in which the switching element is turned on from an off state to an on state,
The current flowing from the booster inductor to the first diode decreases linearly, and the current flowing from the booster inductor through the primary coil of the transformer to the switching element is input from the input power by the primary coil. A power supply, which increases linearly until it is current. The method of claim 5, wherein
In a second driving mode in which the switching element is kept on,
And the first and second diodes are open, and the charge charged in the capacitor is output to the output node through the secondary coil of the transformer. The method of claim 5, wherein
In a third driving mode in which the switching element is off in the on state to maintain the off state,
A second current path is formed that leads to the input power source, the booster inductor, the primary coil of the transformer, the second diode, the secondary coil of the transformer, and the output node, and the current output from the second diode. A portion of which is charged in the capacitor. The method of claim 8,
In a fourth driving mode after the third driving mode in which the switching element maintains an off state,
Charge charged in the capacitor is output to the output node through the secondary coil of the transformer, and the first diode is conducted as the current flowing through the second diode decreases due to the discharge of the capacitor, so that the booster inductor and the And a first current path leading to a first diode and the output node is formed. The method of claim 3, wherein
The current path forming unit,
The transformer having a primary coil linearly increasing a current supplied from the booster inductor to the switching element, and a secondary coil connected to the output node;
A first diode forming the first current path between the primary coil of the transformer and the output node;
A second diode outputting a current output from the booster inductor; And
A capacitor charged by a current output from the second diode,
The secondary coil of the transformer forms the second current path between the second diode and the output node or a third current path between the capacitor and the output node according to the voltage of the capacitor. Power supply. The method of claim 10,
In a first driving mode in which the switching element is turned on from an off state to an on state,
Current flowing from the booster inductor through the primary coil of the transformer to the first diode is linearly reduced by the primary coil of the transformer, and current flowing from the booster inductor to the switching element is input from the input power source. And a linear increase until the input current becomes. The method of claim 10,
In a second driving mode in which the switching element is kept on,
And the first and second diodes are open, and the charge charged in the capacitor is output to the output node through the secondary coil of the transformer. The method of claim 10,
In a third driving mode in which the switching element is off in the on state to maintain the off state,
And the second current path leading to the input power source, the second diode, the secondary coil of the transformer, and the output node is formed, and a portion of the current output from the second diode is charged in the capacitor. Power supply. The method of claim 13,
In a fourth driving mode after the third driving mode in which the switching element maintains an off state,
Charge charged in the capacitor is output to the output node through the secondary coil of the transformer, and the first diode is conducted as the current flowing through the second diode decreases due to the discharge of the capacitor, so that the booster inductor and the And a first current path leading to the primary coil of the transformer and the first diode and the output node. A driving voltage supply unit including the power supply device according to any one of claims 1 to 14;
At least one light emitting diode array connected in parallel to an output node of the power supply; And
And a duty controller configured to generate a switching control signal having a predetermined duty to control switching of the switching elements configured in the power supply device.
And said light emitting diode array comprises a plurality of light emitting diodes electrically connected in series. A liquid crystal display panel which displays a predetermined image by adjusting the light transmittance of the liquid crystal; And
A display device comprising the backlight unit of claim 15 for irradiating light to the display panel. A display panel displaying a predetermined image; And
A display device comprising the power supply device according to any one of claims 1 to 14 for generating power required for driving the display panel.

Images