KR20120048154A - Apparatus for supplying power, back light unit and display apparatus using the same - Google Patents

Abstract

PURPOSE: A power supply device, a display unit, and a back light unit using the same are provided to improve power conversion efficiency by reducing power loss of a main switch device. CONSTITUTION: A first inductor(L1) is connected between a first node and a second node. A main switch(S1) is connected between the second node and a ground power source. The main switch is switched according to a first switching signal. A separation capacitor(Cs) is connected between the second node and a third node. A second inductor(L2) is connected between the third node and the ground power source. A first diode(D1) is connected between the third node and an output node. An anode electrode of a second diode(D2) is connected to the second node. One end of a third inductor(L3) is connected to a cathode terminal of the second diode. An auxiliary switch is switched according to a second switching device.

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 improve power efficiency by reducing power loss of a main switch element.

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). Such power supplies can be buck converters, boost converters, and single-ended primary inductance converters (SEPICs).

1 is a view schematically showing a conventional SEPIC converter.

Referring to FIG. 1, a conventional SEPIC converter includes an input capacitor Cin, an output capacitor Cout, first and second inductors L1 and L2, an isolation capacitor Cs, a diode D, and a main switch element. It consists of S1.

Referring to the driving method of the conventional SEPIC converter as follows.

First, when the main switch element S1 is turned on, input energy is stored in the first inductor L1 and energy stored in the isolation capacitor Cs when the main switch element S1 is turned off. Is discharged to charge the second inductor (L2). At this time, energy charged in the output capacitor Cout is supplied to the load.

On the other hand, when the main switch element S1 is turned off, the energy stored in the first inductor L1 is output to the load and charges the isolation capacitor Cs. At the same time, the energy charged in the second inductor L2 is supplied to the load through the diode D.

As such, the voltage and current conversion ratio of the conventional SEPIC converter may be defined as in Equation 1 below.

In Equation 1, D _S1 represents an on duty of the main switch element S1.

In the case of the conventional SEPIC converter described above, most of the power loss is generated by the switching losses of the main switch element S1 and the heat in the winding resistances of the inductors L1 and L2. The switching loss and the heat loss of the inductor are caused by the current flowing in the converter. The more current flows in the converter, the larger the loss. Accordingly, in the conventional SEPIC converter, since the input / output voltage switching ratio is low, the input current does not go down by that much, and a considerable amount of current flows inside the converter. Thus, a large current circulating inside the converter causes a loss in efficiency by causing switching losses and heat losses in the winding resistance of the inductor.

On the other hand, as a result of experiments with the switch voltage and current waveform of the conventional SEPIC converter designed to have a driving condition of 24V input voltage, 26.5V output voltage, and 2.8A output current, as shown in FIG. SEPIC converter has the following problems.

First, the switch current flows up to 9A and the switch voltage rises up to 108V under the output current of 2.8A.

Second, when the main switch device is turned off, oscillation occurs in both voltage and current, and thus, electromagnetic interference (EMI) may occur.

Third, there is a problem in that the current flowing through the inductor inside the converter also increases, causing winding loss of the inductor.

As a result, the conventional SEPIC converter has a problem that the efficiency is further lowered because the current flowing through the main switch element continues to increase as the level of the output current increases.

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, which can improve power efficiency by reducing power loss of a main switch element.

According to an aspect of the present invention, there is provided a power supply apparatus comprising: a first inductor connected between a first node and a second node connected to an input power source; A main switch connected between the second node and a base power source and switched according to a first switching signal; A separation capacitor connected between the second node and a third node; A second inductor connected between the third node and the base power supply; A first diode connected between the third node and an output node; A second diode having an anode electrode and a cathode electrode, the anode diode being connected to the second node; A third inductor, one end of which is connected to the cathode terminal of the second diode; And an auxiliary switch connected between the other end of the third inductor and the output node and switched according to a second switching signal.

The power supply includes an input capacitor connected between the first node and the base power source; And an output capacitor connected between the output node and the base power supply.

The falling time point of the second switching signal is delayed by a first period from the rising time point of the first switching signal, and the rising time point of the second switching signal is changed from the falling time point of the first switching signal. It is characterized by a delay by two periods.

The first period is a period in which the main switch element and the auxiliary switch element are simultaneously in an on state, and the second period is a conduction period of the first diode.

According to an aspect of the present invention, there is provided a power supply apparatus including: an input power source; A power converter configured to store energy supplied from the input power according to switching of the main switch element according to a first switching signal, and selectively output the stored energy to an output node; And a direct power path unit for selectively forming a power path between the input power source and the output node according to the switching of the auxiliary switch element according to the second switching signal.

The power converter includes a first inductor connected between a first node and a second node connected to the input power source; A connection between the second node and a base power source and switched according to the first switching signal to store energy supplied from the input power source in the first inductor and output energy stored in the first inductor to an output node. The main switch element; Connected between the second node and a third node to store energy output from the first inductor to the output node when the main switch element is OFF, and stored energy when the main switch element is ON A separation capacitor to discharge; A second inductor storing energy discharged by the separation capacitor when the main switch element is turned on and outputting the stored energy to the output node when the main switch element is turned off; And a first diode configured to transfer energy output by the first and second inductors to the output node when the main switch element is turned off.

The direct power path unit includes a second diode having an anode electrode and a cathode electrode, the anode electrode being connected to the second node; And a third inductor connected between the cathode electrode of the second diode and the auxiliary switch element, wherein the auxiliary switch element is connected between the third inductor and the output node and switched according to the second switching signal. And form a current path between the third inductor and the output node.

The third inductor may linearly control a current flowing through the main switch element to soft switch the main switch element.

The third inductor may linearly control a current flowing through the first diode by linearly controlling a current flowing through the auxiliary switch element when the first diode is turned off.

The falling time point of the second switching signal is delayed by a first period from the rising time point of the first switching signal, and the rising time point of the second switching signal is changed from the falling time point of the first switching signal. It is characterized by a delay by two periods.

The first period is a period in which the main switch element and the auxiliary switch element are simultaneously in an on state, and the second period is a conduction period of the first diode.

The first diode is conductive only when the main switch element and the auxiliary switch element are in an OFF state at the same time.

The ON Duty time of the main switch element is longer or shorter than the conduction period of the first diode.

The power supply device outputs an output voltage higher than the input voltage to the output node when the on duty time of the main switch element is longer than the conduction period of the first diode, and the on duty of the main switch element. When the (ON Duty) time is shorter than the conduction period of the first diode, an output voltage lower than the input voltage is output to the output node.

The power converter includes an input capacitor connected between the first node and the base power source; And an output capacitor connected between the output node and the base power supply.

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 the first and second switching signals to control the power supply device, wherein the LED array includes a plurality of LEDs electrically connected in series. .

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 generating power required for driving the display panel.

As described above, the present invention increases the amount of power delivered directly with high efficiency by directly forming a power path between an input and an output through a direct power path unit, and reduces power loss due to switching of the main switch, thereby reducing power conversion efficiency. There is an effect that can be improved.

In addition, the present invention can reduce the switching loss of the main switch element by soft switching the main switch element through the direct power path, and reduces the current level flowing through the main switch element, the main switch element during turn-off of the main switch element There is an effect that the voltage across both sides can be reduced.

1 is a view schematically showing a conventional SEPIC converter.
2 is a waveform diagram illustrating a switching loss generated in a conventional power supply.
3 is a view schematically illustrating a power supply device according to an embodiment of the present invention.
FIG. 4 is a waveform diagram illustrating first and second switching signals according to the first exemplary embodiment for switching each of the main switch element and the auxiliary switch element shown in FIG. 3.
FIG. 5 is a waveform diagram illustrating first and second switching signals according to a second exemplary embodiment for switching each of the main switch element and the auxiliary switch element shown in FIG. 3.
6A through 6C are diagrams illustrating a method of driving a step-up mode step by step in a power supply according to an exemplary embodiment of the present invention.
FIG. 7 is a waveform diagram illustrating voltage and current waveforms according to the driving method of the step-up mode illustrated in FIGS. 6A to 6C.
FIG. 8 is a waveform diagram illustrating voltage and current waveforms according to a driving method of a step-down mode of the power supply device illustrated in FIGS. 6A to 6C.
9A and 9B are waveform diagrams illustrating simulation results of current and voltage waveforms of a main switch element and an auxiliary switch element of a power supply device according to an exemplary embodiment of the present invention.
10 is a diagram schematically illustrating a backlight unit according to an exemplary embodiment of the present invention.
FIG. 11 is a diagram schematically illustrating a display apparatus according to a first exemplary embodiment of the present invention.
12 is a diagram schematically illustrating a display device 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 view schematically illustrating a power supply device according to an embodiment of the present invention.

Referring to FIG. 3, a power supply device 100 according to an embodiment of the present invention includes an input power source Vin, a power converter 110, and a direct power pass unit 120. It is composed.

The input power source Vin is connected between the first node N1 of the first power converter 110 and the base power source. The input power Vin supplies an input voltage of a predetermined level to the first power converter 110 and may be a wall power source or a battery.

The power converter 110 includes an input capacitor Cin, a first inductor L1, a main switch element S1, a separation capacitor Cs, a second inductor L2, a first diode D1, and an output capacitor. (Cout) is configured.

The input capacitor Cin is connected between the first node N1 and the base power supply. The input capacitor Cin stores the voltage supplied from the input power Vin according to the switching of the main switch element S1, and outputs the stored energy.

The first inductor L1 is connected between the first node N1 and the second node N2. That is, one end of the first inductor L1 is connected to the first node N1, and the other end is connected to one end of the separation capacitor Cs through the second node N2. The first inductor L1 stores the energy supplied from the input power Vin and / or the input capacitor Cin according to the switching of the main switch element S1, and outputs the stored energy.

As shown in FIG. 4, the main switch element S1 has a first switching signal SS1 having a predetermined ON duty t _S1 supplied from an external duty controller (not shown). Switched accordingly to control the current flow in the power converter 110. For this purpose, the main switch element S1 includes a gate terminal to which the first switching signal SS1 is supplied, a drain terminal connected to the second node N2, and a source terminal connected to the base power source. The main switch element S1 may be a field effect transistor (FET), an insulated gate bipolar transistor (IGBT), or an integrated gate commutated thyristor (IGCT). .

The main switch element S1 may further include an internal diode formed to be forward biased from the source terminal to the drain terminal.

The separation capacitor Cs is connected between the second node N2 and the third node N3. That is, one end of the separation capacitor Cs is connected to the second node N2 and the other end is connected to the third node N3. The separation capacitor Cs stores energy according to the switching of the main switch element S1 and outputs the stored energy to the load.

The second inductor L2 is connected between the third node N3 and the base power supply. That is, one end of the second inductor L2 is connected to the third node N3 and the other end is connected to the base power source. The second inductor L2 stores energy supplied according to the switching of the main switch element S1 and outputs the stored energy to a load or outputs the separated capacitor Cs to the separated capacitor Cs. Charge it.

The first diode D1 is connected between the third node N3 and the output node No. That is, the anode terminal of the first diode D1 is connected to the third node N3, and the cathode terminal is connected to the output node No. The first diode D1 is conducted according to the voltage level of the third node N3 and the output node No to output energy stored in the first and second inductors L1 and L2 to the output node No. do. In addition, the first diode D1 blocks the reverse current flowing from the output node No toward the third node N3.

The output capacitor Cout is connected between the output node No and the base power supply. That is, one end of the output capacitor Cout is connected to the output node No, and the other end is connected to the base power supply. The output capacitor Cout smoothly and simultaneously stores the voltage output to the load through the output node No when the main switch element S1 is ON, and the main switch element S1. In the OFF state, the stored voltage is output to the load through the output node No. Here, the load may be a light emitting diode (LED), a light emitting diode array (LED array), a backlight unit, various information devices, a display device, or the like.

The output capacitor Cout may be embedded in a load circuit connected to the output node No.

The power converter 110 charges the first inductor L1 at the time of turning on the main switch element S1 according to the first switching signal SS1 and simultaneously stores the energy stored in the separation capacitor Cs. Energy stored in the first and second inductors L1 and L2 is charged when the second inductor L2 is charged and the main switch element S1 is turned off according to the first switching signal SS1. Outputs to the output node (No) and charges the output capacitor (Cout).

The direct power path unit 120 includes a second diode D2, a third inductor L3, and an auxiliary switch element S2.

The second diode D2 is connected between the second node N2 and the third inductor L3. That is, the anode terminal of the second diode D2 is connected to the second node N2, and the cathode terminal is connected to one end of the third inductor L3. The second diode D2 is turned on in accordance with the switching of the auxiliary switch element S2 to supply the current supplied through the second node N2 to the third inductor L3, and the main switch element S1 On turns off the reverse current flowing from the output node No toward the main switch element S1.

The third inductor L3 is connected between the second diode D2 and the auxiliary switching S2. That is, one end of the third inductor L3 is connected to the cathode terminal of the second diode D2, and the other end thereof is connected to the auxiliary switch element S2. The third inductor L3 stores the energy supplied through the second diode D2 according to the switching of the auxiliary switch element S2 to reduce the current level and switching loss flowing through the main switch element S1, thereby reducing the main voltage. Soft switching of the switch element S1.

As shown in FIG. 4, the auxiliary switch element S2 is turned on and off in accordance with the second switching signal SS1 having a predetermined on duty t _S2 supplied from an external pulse width controller (not shown). The energy supplied through the third inductor L3 is supplied to the output node No. To this end, the auxiliary switch element S2 includes a gate terminal to which the second switching signal SS2 is supplied, a drain terminal connected to the other end of the third inductor L3, and a source terminal connected to the output node No. It is configured by. The auxiliary switch element S2 linearly and slowly increases the current supplied from the third inductor L3 according to the second switching signal SS1 due to the continuous current characteristic of the third inductor L3. Therefore, soft switching is performed. The auxiliary switch element S2 may be the same field effect transistor, insulated gate bipolar transistor, or integrated gate rectifier thyristor as the main switch element S1.

Meanwhile, the auxiliary switch element S2 may further include an internal diode formed to be forward biased from the source terminal to the drain terminal.

The falling time of the second switching signal SS2 is delayed by a first period t _RL from the rising time of the first switching signal SS1 and the rising time of the second switching signal SS2. Is delayed by the second period t _D1 from the polling time point of the first switching signal SS1. Here, the first period t _RL is a period in which the main switch element S1 and the auxiliary switch element S2 are on at the same time, and the second period t _D1 is the conduction of the first diode D1. It can be a period of time.

The first period t _RL reduces the inductive turn-off loss of the auxiliary switch element S2 due to the third inductor L3 and at the same time, turns the main switch element S1 on. -Reduces Turn-ON Loss.

The direct power path unit 120 turns off the third inductor L3 by soft switching the auxiliary switch element S2 according to the second switching signal SS2 after the main switching element S1 is turned off. Through the direct formation of the power path of the first inductor (L1) and the output node (No) directly outputs a considerable amount of power directly transmitted to the output node (No) with high efficiency without switching loss.

In addition, the direct power path unit 120 linearly slowly increases the current flowing through the main switch element S1 by using the current characteristic of the third inductor L3 when the main switch element S1 is turned on. Soft switching of the element S1 eliminates the turn-on loss of the main switch element S1 and the turn-off loss of the auxiliary switch element S2.

Further, the direct power path unit 120 linearly and slowly increases the current flowing through the auxiliary switch element S2 when the first diode D1 is turned off by using the current characteristic of the third inductor L3. By linearly and slowly decreasing the current flowing through the first diode D1, the turn-off loss of the first diode D1 and the turn-on loss of the auxiliary switch element S2 are eliminated.

As such, the power supply device 100 according to the embodiment of the present invention has an on time t _S1 of the main switch element S1, an on time t S2 of the auxiliary switch element _S2 , and a first diode ( The conversion ratio of the input / output voltage is determined according to the on time t _{D1 of D1} ).

As described above, in the power supply apparatus 100 according to the embodiment of the present disclosure, the on duty t _S1 time of the first switching signal SS1 may be set to be longer or shorter than the second period t _D1 . In this case, as shown in FIG. 4, when the on duty t _S1 time of the first switching signal SS1 is longer than the second period t _D1 , the power supply device 100 according to the embodiment of the present invention is provided. Is driven in a step-up mode, that is, a boost mode. On the other hand, as shown in FIG. 5, when the on duty t _S1 time of the first switching signal SS1 is shorter than the second period t _D1 , the power supply device 100 according to the embodiment of the present invention. ) Is driven in a step-down mode, that is, a step-down mode.

6A to 6C are diagrams illustrating a method of driving a step-up mode step by step in a power supply device according to an exemplary embodiment of the present invention, and FIG. 7 is a step- diagram shown in FIGS. 6A to 6C. A waveform diagram showing voltage and current waveforms according to a driving method of a step up mode.

6A to 6C will be described step by step driving method in the power supply device according to an embodiment of the present invention in conjunction with FIG. 7 as follows.

First, as shown in FIGS. 6A and 7, the main switch element S1 is turned on using the first switching signal SS1 and the main switch element S1 is used by using the second switching signal SS2. Turns off the auxiliary switch element S2 after the first period t _RL from the turn-on time. Accordingly, due to the continuous current characteristic of the third inductor L3 of the direct power path unit 120 in the section t _{RL in} which the main switch element S1 and the auxiliary switch element S2 are ON at the same time. As the current I _S2 flowing in the auxiliary switch element S2 decreases linearly and slowly, the current I _S1 flowing in the main switch element _S1 also increases linearly and slowly, so that the main switch element S1 soft-switches. Done. Accordingly, the turn-on loss of the main switch element S1 and the turn-off loss of the auxiliary switch element S2 are eliminated when the main switch element S1 is turned on.

During the on time t _S1 of the main switch element S1 in which the auxiliary switch element S2 is turned off and the main switch element S1 is turned on, the input power source Vin and / or the input capacitor ( Energy from Cin is stored in the first inductor L1 and at the same time the second inductor L2 is charged through the discharge of energy stored in the separation capacitor Cs, and the energy stored in the output capacitor Cout is output node No. It is supplied to Load through). At this time, the first diode D1 is open to the voltage difference between the third node N3 and the output node No.

6B and 7, the main switch element S1 is turned off using the first switching signal SS1, and the auxiliary switch element S2 is generated according to the second switching signal SS2. ) To OFF. Accordingly, in the period t _{D1 in} which the main switch element S1 and the auxiliary switch element S2 are turned off at the same time, the first diode D1 is formed by energy stored in the first and second inductors L1 and L2. ) Conducts energy stored in the first inductor L1 to the output node No through the separation capacitor Cs and the first diode D1 and simultaneously charges the separation capacitor Cs, and the second inductor (L1). Energy stored in L2) is also output to the output node No through the first diode D1. At this time, the output capacitor Cout smoothes and stores the voltage output to the output node No.

The first diode D1 is turned on for a second period t _D1 during which the auxiliary switch element S2 is turned on after the main switch element S1 is turned off.

6C and 7, the main switch element S1 is maintained in the OFF state using the first switching signal SS1, while the second switching signal SS2 is maintained according to the second switching signal SS2. The auxiliary switch element S2 is turned on. Accordingly, the energy stored in the first inductor L1 is directly output to the output node No through the second diode D2, the third inductor L3, and the auxiliary switch element S2. At this time, the current I _D1 flowing in the first diode _D1 also linearly increases as the current I _S2 flowing in the auxiliary switch element S2 slowly increases linearly due to the current characteristic of the third inductor L3. By slowly decreasing, the turn-on loss of the auxiliary switch element S2 and the turn-off loss of the first diode D1 are eliminated.

Then, the driving method of the step-up mode is performed by repeatedly performing the operation as shown in FIGS. 6A to 6C according to the first and second switching signals SS1 and SS2. Vin is boosted to a predetermined voltage level and output to the load.

8 is a waveform diagram illustrating voltage and current waveforms according to the driving method of the step-down mode illustrated in FIGS. 6A to 6C.

6A to 6C and FIG. 8, in the power supply apparatus according to the exemplary embodiment of the present disclosure, in the step-down mode, the on-duty t _S1 of the first switching signal SS1 is determined to be the first. Except for less than two periods t _D1 , the operation is performed in the same manner as the above-described driving method of the step-up mode, and thus a detailed description thereof will be replaced with the above description.

According to the driving method of the step-down mode, the input power Vin is repeatedly generated by repeatedly performing the operations shown in FIGS. 6A to 6C according to the first and second switching signals SS1 and SS2. The voltage is reduced to a predetermined voltage level and output to the load.

On the other hand, the results of experimenting with the switch voltage and the current waveform of the power supply device 100 according to the embodiment of the present invention designed to have a driving condition of the input voltage of 24V, the output voltage of 26.5V, and the output current of 2.8A 9A and 9B, the power supply device 100 according to the embodiment of the present invention may be confirmed to have the following effects compared to the conventional power supply device.

First, since the current to be applied by the main switch element S1 is about 5.5A, it can be confirmed that the current reduction is about 2.5A compared to the conventional 8A.

Secondly, the direct power path portion 120 the third inductor due to (L3) main switching element (S1) turns of the the-Main, as turns on the auxiliary switching element (S2) switch current (I _S2) is linearly slowly decrease in It can be seen that the turn-on loss of the main switch element S1 and the turn-off loss of the auxiliary switch element S2 are controlled by slowly increasing the switch current I _S1 of the switch element S1 linearly.

Third, as the switch current I _S2 of the auxiliary switch element S2 increases linearly and slowly when the first diode D1 is turned off, the turn-off loss of the first diode D1 and the auxiliary switch element ( It can be seen that the turn-on loss of S2) is removed.

Fourth, as the level of the switch current I _S1 flowing through the main switch element S1 decreases, the energy stored in the output capacitor Cout decreases so that the main switch element S1 when the main switch element S1 is turned off. It can be seen that the maximum value of the voltage Vds1 at both ends also decreases.

Therefore, the power supply device 100 according to the embodiment of the present invention may include a first power path unit 120 formed of a second diode D2, a third inductor L3, and an auxiliary switch element S2. By directly forming a current path between the inductor L1 and the output node No, a significant amount of power is output directly through the third inductor L3 to the load without switching loss and the remaining voltage and current conversions. Output the required amount of power to the load (Load) through the power converter 110.

As a result, the power supply device 100 according to the embodiment of the present invention reduces the power loss of the main switch element S1 and the first diode D1 through the direct power path unit 120, thereby reducing the DC-DC conversion efficiency. Can improve.

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

Referring to FIG. 10, 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 by using an 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 configured to include a power supply device 100 according to an embodiment of the present invention shown in FIG. Hereinafter, the description of the power supply device 100 will be replaced with the above description of FIGS. 3 to 8.

Each of the plurality of light emitting diode arrays LA1 to LAn corresponds to a load of the driving voltage supply unit 310, that is, the power supply device 100 (see FIG. 3), and the output node of the power supply device 100 ( No) is electrically connected in parallel. 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 device 100 and a base power source.

The duty controller 320 generates the aforementioned first and second switching signals SS1 and SS2 to control switching of each of the main switch element S1 and the auxiliary switch element S2 of the power supply device 100.

The duty controller 320 detects a current flowing in each of the plurality of light emitting diode arrays LA1 to LAn and controls the duty of the first and second switching signals SS1 and SS2 to control the duty of the plurality of light emitting diode arrays LA1 to LAn. The current flowing through LAn is controlled constantly. That is, the duty controller 320 controls the duty of the first and second switching signals SS1 and SS2 to put the power supply 100 in a step-up mode or a step-down mode. By driving, the current flowing through the plurality of light emitting diode arrays LA1 to LAn is constantly controlled.

As described above, the backlight unit 300 according to the embodiment of the present invention controls the switching of each of the main switch element S1 and the auxiliary switch element S2 included in the driving voltage supply unit 310 to control the plurality of light emitting diode arrays. By supplying a constant driving voltage Vd to LA1 to LAn, 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.

FIG. 11 is a diagram schematically illustrating a display apparatus according to a first exemplary embodiment of the present invention.

Referring to FIG. 11, the display device according to the first embodiment of the present invention includes a flat panel display panel 400, a panel driver 500, and a power supply unit 600.

The flat panel 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 flat panel 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. ) May be a display panel of a digital display device.

The panel driver 500 displays an image corresponding to the input data RGB input from the outside on the flat panel 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 necessary for driving the flat panel display panel 400 and the panel driver 500 using input power supplied from the outside. To this end, the power supply unit 600 is configured to include a power supply device 100 according to an embodiment of the present invention shown in FIG. Hereinafter, the description of the power supply device 100 will be replaced with the above description of FIGS. 3 to 8.

12 is a diagram schematically illustrating a display device according to a second exemplary embodiment of the present invention.

Referring to FIG. 12, 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 900, and a power supply 1000.

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 900.

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 may be a source start pulse, a source sampling clock, a source output enable, a polarity control signal POL, or the like.

The gate control signal GCS may be a gate start pulse, a gate shift clock, a gate output enable, or the like.

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 900 irradiates light to the liquid crystal display panel 700 using a light emitting diode (LED). To this end, since the backlight unit 900 is configured to include the backlight unit 300 according to the embodiment of the present invention shown in FIG. 10, a description thereof will be replaced with the above description.

Meanwhile, the backlight unit 900 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 1000 generates driving voltages required to drive each of the liquid crystal display panel 700, the panel driver 800, and the backlight unit 900 by using input power supplied from the outside. To this end, the power supply unit 1000 is configured to include a power supply device 100 according to the first embodiment of the present invention shown in FIG. Hereinafter, the description of the power supply device 100 will be replaced with the above description of FIGS. 3 to 8.

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, 600, 1000: power supply unit 110: power conversion unit
120: direct power pass section 300: backlight unit
310: driving voltage supply unit 320: duty control unit
400: flat panel display panel 500, 800: panel driver

Claims (18)

A first inductor connected between a first node and a second node connected to the input power source;
A main switch connected between the second node and a base power source and switched according to a first switching signal;
A separation capacitor connected between the second node and a third node;
A second inductor connected between the third node and the base power supply;
A first diode connected between the third node and an output node;
A second diode having an anode electrode and a cathode electrode, the anode diode being connected to the second node;
A third inductor, one end of which is connected to the cathode terminal of the second diode; And
And an auxiliary switch connected between the other end of the third inductor and the output node and switched according to a second switching signal. The method of claim 1,
An input capacitor connected between the first node and the base power supply; And
And an output capacitor connected between said output node and said base power supply. The method of claim 1,
The falling time point of the second switching signal is delayed by a first period from the rising time point of the first switching signal,
The rising time point of the second switching signal is delayed by a second period from the polling time point of the first switching signal. The method of claim 3, wherein
The first period is a period in which the main switch element and the auxiliary switch element are on simultaneously.
And said second period is a conduction period of said first diode. Input power;
A power converter configured to store energy supplied from the input power according to switching of the main switch element according to a first switching signal, and selectively output the stored energy to an output node; And
And a direct power path section for selectively forming a power path between the input power source and the output node according to the switching of the auxiliary switch element according to the second switching signal. The method of claim 5, wherein
The power converter,
A first inductor connected between a first node and a second node connected to the input power source;
A connection between the second node and a base power source and switched according to the first switching signal to store energy supplied from the input power source in the first inductor and output energy stored in the first inductor to an output node. The main switch element;
Connected between the second node and a third node to store energy output from the first inductor to the output node when the main switch element is OFF, and stored energy when the main switch element is ON A separation capacitor to discharge;
A second inductor storing energy discharged by the separation capacitor when the main switch element is turned on and outputting the stored energy to the output node when the main switch element is turned off; And
And a first diode transferring energy output by the first and second inductors to the output node when the main switch element is turned off. The method according to claim 6,
The direct power pass unit,
A second diode having an anode electrode and a cathode electrode, the anode diode being connected to the second node; And
A third inductor connected between the cathode electrode of the second diode and the auxiliary switch element,
And the auxiliary switch element is connected between the third inductor and the output node and is switched in accordance with the second switching signal to form a current path between the third inductor and the output node. The method of claim 7, wherein
And the third inductor linearly controls a current flowing through the main switch element to soft switch the main switch element. The method of claim 7, wherein
Wherein the third inductor linearly controls a current flowing through the auxiliary switch element during turn-off of the first diode to linearly control a current flowing through the first diode. Feeding device. The method of claim 7, wherein
The falling time point of the second switching signal is delayed by a first period from the rising time point of the first switching signal,
The rising time point of the second switching signal is delayed by a second period from the polling time point of the first switching signal. The method of claim 10,
The first period is a period in which the main switch element and the auxiliary switch element are on simultaneously.
And said second period is a conduction period of said first diode. The method of claim 7, wherein
And the first diode is conductive only when the main switch element and the auxiliary switch element are in an OFF state at the same time. The method according to claim 6,
ON duty time of the main switch element is longer or shorter than the conduction period of the first diode. The method of claim 13,
The power supply device,
When the ON Duty time of the main switch element is longer than the conduction period of the first diode, an output voltage higher than the input voltage is output to the output node,
And an output voltage lower than the input voltage to the output node when an ON duty time of the main switch element is shorter than a conduction period of the first diode. The method according to claim 6,
The power converter,
An input capacitor connected between the first node and the base power supply; And
And an output capacitor connected between said output node and said base power supply. A driving voltage supply unit including the power supply device according to any one of claims 1 to 15;
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 the first and second switching signals to control 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 16 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 15 for generating power required for driving the display panel.

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