KR102301401B1 - Display apparatus, and control method for the same - Google Patents

Abstract

Provided are a display device for supplying different driving voltages to each of a plurality of LEDs by varying the ground potential of a plurality of LEDs included in an LED module, and a method for controlling the same.
A display device according to an embodiment includes: an LED module including a first LED having a first driving voltage and a second LED having a second driving voltage smaller than the first driving voltage; a common anode node connecting an anode of each of the first LED and the second LED; and a power control unit supplying different driving voltages to the first LED and the second LED through a common anode node. may include.

Description

Display device, and control method thereof

It relates to a display device in which an LED module including a plurality of LEDs is arranged, and a control method therefor.

The display device may refer to a device capable of displaying a broadcast signal or an image signal/image data of various formats.

Such a display device may include a display panel that displays an image using light. In this case, the display panel may be divided into a light-emitting display panel that emits light by itself and a non-emission display panel that does not emit light by itself.

An example of the light emitting display panel is a light emitting diode (LED) panel. The LED panel may be provided such that a plurality of LED modules are arranged in a predetermined direction. Since each of the plurality of LED modules corresponds to each pixel of an image to be displayed, each of the plurality of LED modules may emit light to realize the color of the corresponding pixel.

The light emitted by the plurality of LED modules may include visible light, and in general, the plurality of LED modules may be provided to include a plurality of LEDs that emit light of different wavelengths.

According to an embodiment of the disclosed invention, there is provided a display device and a control method thereof for supplying different driving voltages to each of a plurality of LEDs by varying the ground potential of a plurality of LEDs included in an LED module.

A display device according to an embodiment includes: an LED module including a first LED having a first driving voltage and a second LED having a second driving voltage smaller than the first driving voltage; a common anode node connecting an anode of each of the first LED and the second LED; and a power control unit supplying different driving voltages to the first LED and the second LED through a common anode node. may include.

In addition, the power control unit may apply a first driving voltage to the common anode node and the cathode of the first LED, and apply a second driving voltage to the common anode node and the cathode of the second LED.

Also, the power control unit may apply a common anode potential to the common anode node.

In addition, the power control unit applies a first ground potential determined according to a difference between the magnitude of the common anode potential and the magnitude of the first driving voltage to the cathode of the first LED, and the magnitude of the common anode potential and the magnitude of the second driving voltage. A second ground potential determined according to the difference between , may be applied to the cathode of the second LED.

In addition, the power control unit may apply a higher potential than the cathode of the first LED to the cathode of the second LED.

Also, the power control unit may determine a driving voltage of the second LED based on a change in current applied to the second LED according to a change in the output voltage.

Also, the power control unit may determine the driving voltage of the second LED by checking a change in current applied to the second LED while decreasing the voltage applied to the second LED from the driving voltage of the first LED.

Also, the power control unit may determine the voltage applied to the second LED as the driving voltage of the second LED when the current applied to the second LED decreases.

In addition, the power control unit may distribute the current received from the power source, and respectively output the first driving voltage and the second driving voltage based on the divided current.

In addition, the power control unit may output a first driving voltage based on a current received from the power source and output a second driving voltage based on the outputted first driving voltage.

In addition, the power control unit, a switch for controlling the flow of the input current received from the power source so as to output the driving voltage supplied to the LED module; may include.

A method of controlling a display device according to an embodiment comprises a display device in which an LED module including a first LED having a first driving voltage and a second LED having a second driving voltage smaller than the first driving voltage is arranged, applying a common anode potential to a common anode node connecting an anode of each of the first LED and the second LED; applying a first ground potential to a cathode of the first LED so that a first driving voltage is applied to the first LED; and applying a second ground potential to the cathode of the second LED so that a second driving voltage is applied to the second LED. may include.

In addition, the step of applying the first ground potential includes determining the first ground potential according to a difference between the magnitude of the common anode potential and the magnitude of the first driving voltage, and the applying of the second ground potential includes the magnitude of the common anode potential. The second ground potential may be determined according to a difference between the and second driving voltages.

In addition, the applying of the second ground potential may include applying a second ground potential higher than the first ground potential.

In addition, determining a second driving voltage by changing the voltage supplied to the second LED; may further include.

In addition, the determining of the second driving voltage may include changing a voltage supplied to the second LED; checking the current flowing through the second LED according to the changed supply voltage; and determining a second driving voltage based on the identified current. may include.

In addition, changing the voltage supplied to the second LED may reduce the voltage supplied to the second LED from the first driving voltage.

Also, in the determining of the second driving voltage based on the identified current, a voltage at a time when the current applied to the second LED is reduced may be determined as the driving voltage of the second LED.

According to an embodiment of the display device and the control method thereof, different driving voltages may be applied to each of a plurality of LEDs included in the LED module. As a result, the energy efficiency of the display device may increase. In addition, since heat generation inside the display device is reduced, durability of the display device may be increased, and thus reliability of performance may be increased.

In addition, since it includes a conventional LED module in which the anodes of the plurality of LEDs are connected and the cathodes are separated, compatibility can be increased when manufacturing a display device.

1A and 1B are external views of display devices according to various embodiments.
2 is a cross-sectional view of a display device according to an exemplary embodiment.
3A and 3B are circuit diagrams of an LED module according to various embodiments.
4 is a control block diagram of a display apparatus according to an exemplary embodiment.
FIG. 5 is a control block diagram specifically showing an LED module of one of the display panels in FIG. 4 . 6 is a circuit diagram for explaining a conventional voltage supply method to the LED module.
7A and 7B are circuit diagrams for explaining a voltage supply method to an LED module according to various embodiments.
8A and 8B are circuit diagrams of a display device for explaining a power supply unit according to various embodiments.
9 is a flowchart of a method for controlling a display apparatus according to an exemplary embodiment.

Hereinafter, a display device and a control method thereof will be described in detail with reference to the accompanying drawings.

1A and 1B are external views of display devices according to various embodiments.

The display device 2 may refer to a device that displays an image received from the outside or an image generated by itself so that a user can visually recognize it.

As shown in FIG. 1A , the display device 2 may include a display panel 1 for displaying an image and a bezel 2a provided to protect the outside of the display panel 1 .

The display panel 1 is implemented with a plurality of pixels, and each of the plurality of pixels may emit light in a visible ray region. Since the light emitted from the plurality of pixels is transmitted into the user's volume, the user can recognize an image through the display panel 1 .

The bezel 2a may help to stably provide an image to a user by fixing the position of the display panel 1 , and may serve to block damage to the display panel 1 from the outside.

To this end, the bezel 2a may be embodied as a highly durable metal, or alternatively may be embodied as a synthetic resin.

1A illustrates a case in which the display device 2 includes one display panel 1 . An embodiment of the display device 2 including one display panel 1 may include a television.

On the other hand, the display device 3 may include a plurality of display panels 1 . In FIG. 1B, the display apparatus 3 in which the display apparatus 2 of FIG. 1A is provided in multiple adjoins is disclosed.

When a plurality of display panels are connected as shown in FIG. 1B , a larger image may be provided to the user. Accordingly, the display device 3 of FIG. 1B may be used to provide images through a large screen to a plurality of users.

An embodiment of the display device 3 including the plurality of display panels 1 may include a large format display (LDF) and a signage.

The display panel 1 of FIGS. 1A and 1B may be implemented as an LED panel 200 in which a plurality of LED modules 210 are arranged. Hereinafter, the display device 2 including the LED panel 200 will be described in detail.

2 is a cross-sectional view of the display device 2 according to an embodiment, and FIGS. 3A and 3B are circuit diagrams of the LED module 210 according to various embodiments.

Referring to FIG. 2 , the display device 2 includes a display panel 200 receiving power to display an image; a driving circuit 300 provided on the rear surface of the display panel 200 to control the current supplied to the display panel 200; and a transparent panel 100 provided on the front of the display panel 200 to block the display panel 200 from the outside; may include.

The transparent panel 100 may be installed on the front surface of the display panel 200 to protect the front surface of the display panel 200 from the outside. To this end, the transparent panel 100 may be implemented with a material having excellent durability. In addition, since the transparent panel 100 is provided on the front surface of the display panel 200 , it may be provided to transmit light emitted from the front surface of the display panel 200 .

The driving circuit 300 may control an electrical signal flowing into the display panel 200 . Specifically, the driving circuit 300 transmits an image signal including image information to be displayed to the display panel 200, and the display panel 200 emits light according to the image signal so that the user can visually recognize the image. have.

In FIG. 2 , the driving circuit 300 is installed on the rear side of the display panel 200 , but the driving circuit 300 can be freely installed within the technical idea that does not interfere with the path of light generated from the display panel 200 . can

The bezel 2a is installed on the outside of the transparent panel 100 , the display panel 200 , and the driving circuit 300 to fix their positions. In addition, a chassis 2b may be installed on the rear surface of the driving circuit 300 to be connected to the bezel 2a. Through this, the transparent panel 100 , the display panel 200 , and the driving circuit 300 may be positioned in the internal space formed by the chassis 2b .

The display panel 200 may provide an image to the user by emitting light when an image signal, which is an electrical signal, is applied. The display panel 200 may be classified into a light-receiving panel structure and a self-luminous panel structure according to a light generation method. In the light-receiving panel structure, since the panel does not emit light by itself, the display apparatus 100 must include a separate backlight unit that generates and supplies light to the display panel 200 . However, the self-luminous panel structure does not require a separate backlight configuration since the display panel 200 emits light by itself. It is assumed that the display panel 200 to be described below adopts a self-luminous panel structure.

In order to represent each pixel of the image, the display panel 200 may include a plurality of LED modules 210 that generate light by itself. At this time, the plurality of LED modules 210 may be arranged in a predetermined direction. For example, the plurality of LED modules 210 may be arranged in a first direction and at the same time arranged in a second direction perpendicular to the first direction. As a result, the display panel 200 may display a two-dimensional image.

When the plurality of LED modules 210 are arranged in two dimensions, the driving circuit 300 may individually provide an image signal to each of the plurality of LED modules 210 . To this end, the driving circuit 300 may include a number of driving circuits 300 corresponding to the number of LED modules 210 arranged on the display panel 200 . Each of the plurality of driving circuits 300 may individually transmit an image signal to the corresponding LED module 210 to control the light generated by each of the plurality of LED modules 210 .

Alternatively, the driving circuit 300 may control the plurality of LED modules 210 arranged in two dimensions for each row or column. If the driving circuit 300 controls the plurality of LED modules 210 in units of columns, the LED modules 210 belonging to the same column may be sequentially activated with a time difference. This will be described in detail with reference to FIG. 4 .

The plurality of LED modules 210 may generate light including visible light, and through this, an image formed by a plurality of pixels may be realized. To this end, the plurality of LED modules 210 may include a red LED 211 , a green LED 212G, and a blue LED 212B.

Referring to Figure 3a, the LED module 210 is a red LED (211); Green LED (212G); and blue LED 212B; including, a common anode node 213 connecting an anode through which a current flows to each LED; may further include.

Such an LED module 210 is called a common anode type.

In addition, the LED module 210 may include a plurality of green LEDs 212G. Referring to FIG. 3B , the case in which the LED module 210 includes two green LEDs 212G1 and 212G2 is exemplified. Even in this case, the LED module 210 may provide a common anode node 213 connecting the anodes of the red LED 211 , the plurality of green LEDs 212G1 and 212G2 , and the blue LED 212B.

As such, since the LED module 210 can generate red, green, blue, or a combination thereof, the LED module 210 can visually implement each pixel of an image.

Meanwhile, the red LED has a different driving voltage than the green or blue LED 212B. Specifically, the red LED 211 emits light when a voltage of about 2.0V is applied, but the green or blue LEDs 212G and 212B emit light when a voltage of about 3.5V is applied. In this case, it is necessary to apply a voltage by distinguishing the red LED 211 from the other LEDs 212G and 212B.

Hereinafter, the display device 2 for supplying different driving voltages by varying the grounding of LEDs having different driving voltages will be described.

4 is a control block diagram of a display device according to an embodiment, FIG. 5 is a control block diagram specifically showing one LED module among the display panels in FIG. 4 , and FIG. 6 is a conventional voltage for the LED module It is a circuit diagram for explaining a supply method, and FIGS. 7A and 7B are circuit diagrams for explaining a voltage supply method for an LED module according to various embodiments.

Referring to FIG. 4 , the display device 2 includes a power supply unit 400 for supplying voltage and current input from an external power source P; a display panel 200 receiving a driving voltage and a driving current from the power supply unit 400 and emitting light; and a driving circuit 300 for controlling a driving voltage and a driving current supplied to the display panel; may include.

The power supply unit 400 includes a power control unit 410 that receives power supplied from the outside and provides it to the display panel; And a scan switch 490 for connecting any one row or column of the plurality of LED modules of the display panel to the power control unit; may include.

The power control unit 410 may provide driving power for the LED module 210 of the display panel 200 to emit light. In particular, the power control unit 410 may provide different voltages to each of the plurality of LEDs having different driving voltages among the LED modules 210 . Details on this will be described later.

The scan switch 490 is any one of the plurality of LED modules 210 so that the power provided from the power supply unit 400 is transferred to any one row or column of the plurality of LED modules 210 of the display panel 200 . A row or column may be connected to the power control unit 410 .

In FIG. 4 , the scan switch 490 exemplifies a case in which any one row of the plurality of LED modules 210 and the power control unit 410 are connected. As a result, power can be supplied to the entire plurality of LED modules 210 belonging to any one row.

The scan switch 490 may change the row or column of the plurality of LED modules 210 connected to the power control unit 410 at predetermined time intervals. For example, the scan switch 490 may be connected to the power control unit 410 by sequentially changing the rows of the plurality of LED modules 210 at predetermined time intervals. Hereinafter, this operation of the scan switch 490 is referred to as scanning.

In FIG. 4 , the scan switch 490 may perform a scan on the plurality of LED modules 210 according to a predetermined scanning period. That is, the scan switch 490 may sequentially change the rows of the plurality of LED modules 210 for each scan time. For example, after the scan switch 490 of FIG. 4 connects the first row of the plurality of LED modules 210 and the power control unit 410, the second row of the plurality of LED modules 210 and the power after the scan time A control unit 410 may be connected. In this way, the scan switch 490 may sequentially scan rows 1 to m of the plurality of LED modules 210 .

Since the image provided to the user through the display device 2 typically has a frame rate of 15 fps to 30 fps, the scan switch 490 selects a scan time shorter than the frame period of the provided image. Injections can be performed with Specifically, the scan time of the scan switch 490 may be determined as a value obtained by dividing the frame period by the number of rows of the plurality of LED modules 210 or less.

The driving circuit 300 may be connected to a row or column of the plurality of LED modules 210 to control power supplied to the row or column of the LED module 210 . Specifically, when the power supply unit 400 is connected to each row of the plurality of LED modules 210 , the driving circuit 300 may be connected to each column of the plurality of LED modules 210 . Conversely, when the power supply 200 is connected to each column of the plurality of LED modules 210 , the driving circuit 300 may be connected to each row of the plurality of LED modules 210 .

4 exemplifies a case in which the driving circuit 300 is connected to each column of the plurality of LED modules 210 . According to the scan of the scan switch 490, power is sequentially supplied to each of the plurality of LED modules 210 belonging to each row, so that the driving circuit 300 includes the plurality of LED modules 210 belonging to the row to which power is supplied. ) You can control the amount of power supplied according to the column in which each is located.

For example, when the scan switch 490 is connected to the first row of the plurality of LED modules 210, the first column driving circuit 300-1 controls the power supplied to the LED module of the first row among the LED modules of the first row. You can control the size. At the same time, the second column driving circuit 300 - 2 may control the amount of power supplied to the LED modules in the second column among the LED modules in the first row. In the same way, the n-th column driving circuit 300-n may control the amount of power supplied to the n-th column of the LED modules of the first row.

In addition, when the scan switch 490 is connected to the m row of the plurality of LED modules 210 , the driving circuit may control the size of power of each of the plurality of LED modules belonging to the m row in the same manner as in the above-described method.

As a result, the size of the power supplied to each of the plurality of LED modules 210 is controlled, so that the display panel 200 can provide one image through the light generated by the plurality of LED modules 210 .

As described above, the power control unit 410 may provide different voltages to each of the plurality of LEDs having different driving voltages among the LED modules 210 . This will be described with reference to FIG. 5 .

The control block diagram of FIG. 5 shows only one LED module 210 in the display panel 200 of FIG. 4 , and the illustrated LED module 210 is connected to the power control unit 410 by the scan switch 490 . case is exemplified. For convenience of description, the scan switch 490 is omitted in FIG. 5 .

The LED module 210 may include a first LED 212 having a first driving voltage and a second LED 211 having a second driving voltage smaller than the first driving voltage. The first LED 212 may include a green LED 212G and a blue LED 212B as an embodiment, and the second LED 211 may include a red LED 212R as an embodiment.

Also, as described above, the anode of each of the first LED 212 and the second LED 211 may be connected by a common anode node 213 . As such, the LED module 210 may be implemented in a common anode method.

Referring to FIG. 6 , in the LED module 210 implemented in the common anode method, each LED may be connected in parallel to the common anode node 213 . In this case, in the prior art, the same voltage was supplied to each of the plurality of LEDs. Specifically, when the voltage Vcc is supplied through the common anode node 213 , the voltage VL is equally applied to each of the plurality of LEDs.

If VL is 3.5V, which is the driving voltage of the green LED 212G and the blue LED 212B, a voltage greater than the driving voltage of 2.0V may be applied to the red LED 211 . As a result, the red LED 211 emits power corresponding to the voltage supplied above the driving voltage as thermal energy. Since the LED module 210 and the driving circuit 300 are vulnerable to heat, when heat is generated, the performance of the display device 2 may be deteriorated.

Accordingly, different driving voltages need to be supplied to the first LED 212 and the second LED 211 . To this end, the voltage applied to the common anode node 213 and the cathodes 212Ga and 212Ba of the first LED may be different from the voltage applied to the common anode node 213 and the cathode 211a of the second LED.

Referring to FIG. 7A , two supply voltages, Vcc1 and Vcc2 , may be supplied to the LED module 210 and the driving circuit 300 . The supply voltage Vcc1 forms a loop with the green LED 212G and the blue LED 212B that are the first LED 212 and the first driving circuit 320 connected thereto, and the supply voltage Vcc2 is the red LED that is the second LED 211 . A loop may be formed with the LED 211 and the second driving circuit 320 connected thereto.

In this case, the common anode potential Vcc1 is supplied to the common anode node 213 , and the first driving circuit 320 connected to the cathodes 212Ga and 212Ba of the first LED may be grounded with the earth (0V). In addition, the second driving circuit 320 connected to the cathode 211a of the second LED may be grounded at a potential Vcc1-Vcc2 . That is, the same common anode potential is applied to the anode 213 of the first LED 212 and the second LED 211 , but different potentials may be applied to the cathodes 211a, 212Ga, and 212Ba.

As a result, a driving voltage VL1 may be supplied to the first LED 212 , and a driving voltage VL2 different from VL1 may be supplied to the second LED 211 . In particular, if the potential applied to the cathode 211a of the second LED is an anode, VL2 may be smaller than VL1.

As such, the driving voltage applied to the first LED 212 and the second LED 211 is applied to the cathodes 212Ga and 212Ba of the first LED 212 and the cathode 211a of the second LED 211 in particular. When the ground potential is changed, there is no unnecessary and excessively applied voltage, so that heat generated in the LED module 210 or the driving circuit can be reduced.

As such, if the potentials applied to the cathodes 212Ga and 212Ba of the first LED and the cathode 211a of the second LED are different, the LED module 210 may be implemented as shown in FIG. 3B . That is, the first LED 212 may include two green LEDs 212G1 and 212G2 and one blue LED 212B.

Referring to FIG. 7B , it can be seen that the driving voltage VL1 is applied to the first green LED 212G1 , the second green LED 212G2 , and the blue LED 212B, while VL2 is applied to the red LED 211 . . This is because the ground potential to which the cathode 211a of the second LED and the cathodes 212Ga and 212Ba of the first LED are connected is different.

Specifically, two supply voltages Vcc1 and Vcc2 may be supplied to the LED module 210 and the driving circuit 300 . The supply voltage Vcc1 forms a loop with the first green LED 212G1, the second green LED 212G1 and the blue LED 212B, which are the first LEDs 212, and the first driving circuit 320 connected thereto, and the supply voltage Vcc2 may form a loop with the red LED 211 as the second LED 211 and the second driving circuit 320 connected thereto.

In this case, the common anode potential Vcc1 is supplied to the common anode node 213 , and the first driving circuit 320 connected to the cathodes 212Ga and 212Ba of the first LED may be grounded with the earth (0V). In addition, the second driving circuit 320 connected to the cathode 211a of the second LED may be grounded at a potential Vcc1-Vcc2 .

As a result, a common anode potential Vcc1 is equally applied to the anodes of the first LED 212 and the second LED 211, but the cathodes 212Ga. 212Ba of the first LED and the cathode 211a of the second LED are each other. Different ground potentials can be applied. Specifically, the ground potential applied to the cathode 212Ga. 212Ba of the first LED is the first ground potential Vcc-VL1, and the ground potential applied to the cathode 211a of the second LED is the second ground potential Vcc1-VL2. can

Through this, a driving voltage VL1 may be supplied to the first LED 212 , and a driving voltage VL2 different from VL1 may be supplied to the second LED 211 .

If the circuit is configured so that the ground potential applied to the ground electrode of each LED is different as described above, different driving voltages can be applied to each LED.

7A and 7B, it may be possible to apply different driving voltages by applying different ground potentials to cathodes of LEDs having different driving voltages. As such, in order to apply different ground potentials to the cathodes of the plurality of LEDs, the power control unit 410 may be implemented as a switching mode power supply (SMPS). Hereinafter, the power control unit 410 will be described in detail with reference to FIGS. 7A and 7B .

8A and 8B are circuit diagrams of a display device for explaining a power control unit according to various embodiments.

The switched mode power supply may refer to a device that converts a voltage using a switch implemented with a semiconductor device such as a MOSFET. Specifically, the switching mode power supply outputs an output voltage using a switch when an input voltage is input, and information on the output voltage is used to control the switch.

The switching mode power supply has higher efficiency and stronger durability than the linear type power supply, and may be advantageous for small size and light weight.

The switching mode power supply is divided into a non-isolation type switching mode power supply that does not use a transformer and an isolation type switching mode power supply that uses a transformer.

Hereinafter, an isolated switching mode power supply, in particular, a switching mode power supply implemented in a flyback method will be described on the assumption. However, since this is only an embodiment of the switched mode power supply, the present invention is not limited thereto.

When the circuit is configured as shown in FIG. 7A , Vcc1 should be supplied to the loop including the first LED 212 and Vcc2 should be supplied to the loop including the second LED 211 . Accordingly, the power control unit 410 may include a first power control unit 401 supplying Vcc1 and a second power control unit 402 supplying Vcc2.

Referring to FIG. 8A , the power control unit 410 includes a rectifier 411 for rectifying an AC voltage input from the outside into a DC voltage; a first power control unit 401 receiving the rectified voltage and outputting a first output voltage; and a second power control unit 402 receiving the rectified voltage and outputting a second output voltage; may include.

The rectifier 411 may be connected to an external power source P to receive power. Also, the rectifier 411 may rectify an input voltage among the received power to a predetermined DC voltage. In this case, the rectified DC voltage may be determined by the element value of the internal circuit of the rectifier 411 .

As shown in FIG. 8A , the rectifier 411 may be implemented as a bridge rectifier. However, the rectifier 411 is not limited thereto, and may be implemented in various ways within the technical idea of generating a constant DC output according to an AC input.

The first power control unit 401 and the second power control unit 402 may be installed in parallel at the output terminal of the rectifier 411 .

The first power control unit 401 includes a first transformer implemented with a 1-1 inductor 440a and a 2-1 inductor 450a; a 1-1th capacitor 420a connected in parallel with the 1-1th inductor 440a; a first switch 430a for controlling the current applied to the 1-1 inductor 440a; a first diode 460a connected to the 2-1 inductor 450a; and a 2-1 th capacitor 470a connected in parallel with the 2-1 th inductor 450a.

When the first switch 430a is turned on, the voltage rectified by the rectifier 411 is applied to the 1-1 inductor 440a so that a current flows. Correspondingly, a voltage in a direction opposite to that of the 1-1 inductor 440a may be applied to the 2-1 th inductor 450a. At this time, since the reverse bias is applied to the first diode 460a connected to the 2-1 th inductor 450a and cut off, no current flows.

Accordingly, energy may be charged in the 1-1 capacitor 420a by the current flowing in the 1-1 inductor 440a, but no current flows in the 2-1 inductor 450a, so that the 2-1th capacitor ( 470a) is not charged with energy.

On the other hand, when the first switch 430a is turned off, a voltage opposite to that when the first switch 430a is turned on may be applied to the 2-1 th inductor 450a. As a result, a forward bias may be applied to the first diode 460a so that energy may be charged in the 2-1 th capacitor 470a.

Accordingly, the output voltage of Vcc1 may be finally output from the output terminal of the first power control unit 401 .

As shown in FIG. 8A , the output Vcc1 may be connected to the first LED 212 of the LED module 210 to supply the first driving voltage VL1 to the first LED 212 .

In the same manner as the first power control unit 401, the second power control unit 402 also includes a second transformer implemented by the 1-2 inductor 440b and the 2-2 inductor 450b; a 1-2-th capacitor 420b connected in parallel with the 1-2-th inductor 440b; a second switch 430b for controlling the current applied to the 1-2 inductor 440b; a second diode 460b connected to the 2-2 second inductor 450b; and a 2-2nd capacitor 470b connected in parallel with the 2-2nd inductor 450b.

A method in which the second power control unit 402 outputs a voltage may be the same as that of the first power control unit 401 .

In this case, the second power control unit 402 may output a voltage Vcc2 different from the output voltage of the first power control unit 401 . Referring to FIG. 7A , the output Vcc2 may be connected to the second LED 211 of the LED module 210 to supply the second driving voltage VL2 to the second LED 211 .

As such, in order to output different voltages, the first power control unit 401 and the second power control unit 402 may be grounded with different voltages. Specifically, the ground potential applied to the ground terminal among the output terminals of the first power control unit 401 and the ground potential applied to the ground terminal among the output terminals of the second power control unit 402 may be different.

For example, the first power control unit 401 may be grounded to the ground (0V), while the second power control unit 402 may be grounded to Vcc1-Vcc2 of a higher voltage than the ground. As a result, Vcc1 may be supplied to the first loop to which the first LED 212 is connected, and Vcc2 may be supplied to the second loop to which the second LED 211 is connected.

8A illustrates a case in which the power supply unit outputs a first output voltage for applying a first driving voltage and a second output voltage for applying a second driving voltage, respectively. Alternatively, it may be possible for the power control unit 410 to output the first output voltage and convert the first output voltage to output the second output voltage.

Referring to FIG. 8B , the power control unit 410 includes a rectifier 411 for rectifying an AC voltage input from the outside into a DC voltage; a transformer implemented with a first inductor 440 and a second inductor 450; a first capacitor 420 connected in parallel with the first inductor 440; a switch 430 controlling the current applied to the first inductor 440; a diode 460 coupled to the second inductor 450; and a 2-1-th capacitor 470a connected in parallel with the second inductor 450; a DC/DC converter 480 for converting the voltage output through the 2-1th capacitor 470a; and a 2-2 second capacitor 470b connected in parallel to the DC/DC converter 480; may include.

When the switch 430 is turned on, the voltage rectified by the rectifier 411 is applied to the first inductor 440 so that a current flows. Correspondingly, a voltage in a direction opposite to that of the first inductor 440 may be applied to the second inductor 450 . At this time, since a reverse bias is applied to the diode 460 connected to the second inductor 450 and cut off, no current flows.

Accordingly, energy may be charged in the first capacitor 420 by the current flowing in the first inductor 440 , but no current flows in the second inductor 450 , so energy is charged in the 2-1 th capacitor 470a doesn't happen

On the other hand, when the switch 430 is turned off, a voltage opposite to that when the switch 430 is turned on may be applied to the second inductor 450 . As a result, a forward bias may be applied to the diode 460 so that energy may be charged in the 2-1 th capacitor 470a.

Accordingly, the first output voltage of Vcc1 may be output from the 2-1 th capacitor 470a. As a result, the output Vcc1 may be connected to the first LED 212 of the LED module 210 to supply the first driving voltage VL1 to the first LED 212 .

Meanwhile, the DC/DC converter 480 may convert the output first output voltage Vcc1 into the second output voltage Vcc2 . In this case, the DC/DC converter 480 may be implemented in various ways within the technical idea of outputting an input DC voltage as a converted DC voltage.

The second output voltage thus output may be charged in the 2-2 th capacitor 470b, and may be stably supplied to the second node. As a result, Vcc2 may be connected to the second LED 211 of the LED module 210 to supply the second driving voltage VL2 to the second LED 211 .

As such, in order to output different voltages, the terminal from which the first output voltage is output and the terminal from which the second output voltage is output may be grounded with different voltages. Specifically, the ground potential applied to the ground terminal among the output terminals from which the first output voltage is output and the ground potential applied to the ground terminal among the output terminals from which the second output voltage is output may be different.

For example, when the first output voltage is connected to the first loop, the first loop is grounded to ground (0V), while the second loop to which the second output voltage is connected is grounded to Vcc1-Vcc2 of a higher voltage than ground. can be As a result, Vcc1 may be supplied to the first loop to which the first LED 212 is connected, and Vcc2 may be supplied to the second loop to which the second LED 211 is connected.

Since the above-described circuit is only an embodiment of the power control unit 410, the power control unit 410 can be implemented in various ways within the technical idea of supplying voltages by varying the ground potential of each LED having different driving voltages.

Meanwhile, the power control unit 410 may find the driving voltage of the second LED 211 by changing the second output voltage supplied to the second loop.

Specifically, the power control unit 410 sets the output voltage for applying the first driving voltage to the second LED 211 as the second output voltage, and checks the current flowing through the second LED 211 at this time. Then, while decreasing the second output voltage, a change in the current flowing through the second LED 211 is checked.

For example, the output voltage Vcc1 for applying the first driving voltage VL1 is output from the second output terminal, and the current flowing through the second LED 211 at this time is checked. That is, the current when the first driving voltage VL1 is applied to the second LED 211 is checked. Then, while decreasing the second output voltage from Vcc1, a change in current flowing through the second LED 211 is checked.

If the voltage applied to the second LED 211 is equal to or greater than the second driving voltage, the current flowing through the second LED 211 has a constant value. However, if the voltage applied to the second LED 211 is less than the second driving voltage, the current flowing through the second LED 211 may change.

Accordingly, the voltage applied to the second LED 211 at a time when the current flowing through the second LED 211 changes may be determined as the second driving voltage. When the second driving voltage is determined in this way, a second ground potential corresponding to the second driving voltage may be applied to the cathode 211a of the second LED.

As such, by applying an optimal driving voltage to an LED having a small driving voltage among a plurality of LEDs included in the LED module 210, power efficiency can be increased.

8 is a flowchart of a method for controlling a display apparatus according to an exemplary embodiment.

First, power may be supplied from the outside. (800) The power supplied from the outside may be direct current or alternating current, and in the case of receiving AC power, a step of rectifying to direct current power may be added.

A driving current may be applied to the common anode node 213 based on the power supplied in this way. (810) At this time, the common anode node 213 is the first LED 212 and the second LED 212 having different driving voltages. It may mean a node connecting the anodes of the LED 211 .

The driving current applied to the common anode node 213 may be supplied to the first LED 212 as the first driving current i1 , so that the first driving voltage VL1 may be applied to the first LED 212 ( 820 ). For this, a first ground potential may be applied to the cathodes 212Ga and 212Ba of the first LED.

As a result, the first driving current i1 may be discharged through the cathodes 212Ga and 212Ba of the first LED ( 830 ). Through this process, the first LED 212 emits light of a corresponding wavelength. can For example, when the first LED 212 is the green LED 212G, the first LED 212 may emit green light by applying a first driving voltage.

Also, among the driving currents applied to the common anode node 213 , i2 , which is the second driving current of the second LED 211 , may be applied to the second LED 211 . As a result, the second driving voltage VL2 may be applied to the second LED 211 ( 840 ). To this end, a second ground potential may be applied to the cathode 211a of the second LED.

As a result, the second driving current i2 may be discharged through the cathode 211a of the second LED ( 850 ). Finally, the second LED 211 may emit light having a corresponding wavelength. For example, when the second LED 211 is the red LED 211 , the second LED 211 may emit red light.

1, 200: display panel
2, 3: display device
210: LED module
211: second LED
212: first LED
300: drive circuit
400: power supply
410: power control unit

Claims (18)

an LED module including a first LED having a first driving voltage and a second LED having a second driving voltage smaller than the first driving voltage;
a common anode node connecting an anode of each of the first LED and the second LED; and
a power control unit supplying the different driving voltages to the first LED and the second LED through the common anode node; including,
The power control unit
applying a common anode potential to the common anode node;
A display device for applying a first ground potential to a cathode of the first LED and a second ground potential different from the first ground potential to a cathode of the second LED. The method of claim 1,
The power control unit,
A first driving voltage is applied to the common anode node and a cathode of the first LED, and a second driving voltage is applied to the common anode node and a cathode of the second LED. delete According to claim 1,
the first ground potential is determined according to a difference between a magnitude of the common anode potential and a magnitude of the first driving voltage;
The second ground potential is determined according to a difference between a magnitude of the common anode potential and a magnitude of the second driving voltage. According to claim 1,
The first ground potential is higher than the second ground potential. The method of claim 1,
The power control unit,
A display device for determining a driving voltage of the second LED based on a change in current applied to the second LED according to a change in an output voltage. 7. The method of claim 6,
The power control unit,
A display device for determining a driving voltage of the second LED by checking a change in current applied to the second LED while decreasing the voltage applied to the second LED from the first driving voltage. 8. The method of claim 7,
The power control unit,
A display device for determining a voltage applied to the second LED as a driving voltage of the second LED when the current applied to the second LED decreases. 3. The method of claim 2,
The power control unit,
A display device that divides a current received from a power source and outputs a first output voltage for supplying the first driving voltage and a second output voltage for supplying the second driving voltage, respectively, based on the divided current. 3. The method of claim 2,
The power control unit,
output a first output voltage for applying the first driving voltage based on the current received from the power source, and a second output voltage for applying the second driving voltage based on the outputted first output voltage output display device. The method of claim 1,
The power control unit,
a switch for controlling the flow of input current received from a power source to output the driving voltage supplied to the LED module; A display device comprising a. In the display device in which an LED module is arranged including a first LED having a first driving voltage and a second LED having a second driving voltage smaller than the first driving voltage,
applying a common anode potential to a common anode node connecting an anode of each of the first LED and the second LED;
applying a first ground potential to a cathode of the first LED so that the first driving voltage is applied to the first LED; and
applying a second ground potential to the cathode of the second LED so that the second driving voltage is applied to the second LED; including,
The first ground potential is different from the second ground potential. 13. The method of claim 12,
Applying the first ground potential comprises:
determining the first ground potential according to a difference between the magnitude of the common anode potential and the magnitude of the first driving voltage;
Applying the second ground potential comprises:
A control method of a display device for determining the second ground potential according to a difference between the magnitude of the common anode potential and the magnitude of the second driving voltage. 13. The method of claim 12,
Applying the second ground potential comprises:
A control method of a display device for applying the second ground potential higher than the first ground potential. 13. The method of claim 12,
determining the second driving voltage by changing the voltage supplied to the second LED; Control method of a display device further comprising a. 16. The method of claim 15,
The step of determining the second driving voltage comprises:
changing the voltage applied to the second LED;
checking a current flowing through the second LED according to the changed applied voltage; and
determining the second driving voltage based on the identified current; A control method of a display device comprising a. 17. The method of claim 16,
Changing the voltage applied to the second LED comprises:
A method of controlling a display device for reducing a voltage applied to the second LED from the first driving voltage. 18. The method of claim 17,
Determining the second driving voltage based on the identified current comprises:
A control method of a display device for determining an applied voltage at a time when the current applied to the second LED decreases as a driving voltage of the second LED.

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