KR100790715B1 - Backlight unit using light emitting diode - Google Patents

Abstract

By connecting a plurality of LEDs used in the surface light source with an appropriately mixed electrical connection structure in series and parallel, and driving a plurality of LEDs emitting the same color by using a single drive circuit to improve the efficiency of driving LED Disclosed is a backlight unit using an LED. The backlight unit includes: a plurality of LED modules including a plurality of red LEDs electrically connected to each other, a plurality of green LEDs electrically connected to each other, and a plurality of blue LEDs electrically connected to each other; A red LED driving circuit which drives a plurality of red LEDs included in the plurality of LED modules in common, a green LED driving circuit which drives a plurality of green LEDs included in the plurality of LED modules in common, and the plurality of LED modules An LED driver including a blue LED driving circuit for driving a plurality of blue LEDs included in common, wherein a plurality of red LED, green LED and blue LED included in each LED module is electrically connected to each other between the LED of the same color Characterized in that formed.

Liquid Crystal Display (LCD), Light Emitting Diode (LED), Backlight

Description

Backlight unit using LED {BACKLIGHT UNIT USING LIGHT EMITTING DIODE}

1 is a configuration diagram showing an example of a conventional direct type backlight unit.

2 to 7 are diagrams illustrating a backlight unit according to various embodiments of the present invention.

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

200, 300, 400, 500, 600, 700: Backlight unit

210, 310, 410, 510, 610, 710: LED module

211, 311a, 311b, 411, 511a, 511b, 611, 711a, 711b: red LED array

212, 312a, 312b, 412, 512a, 512b, 612, 712a, 712b: green LED array

213, 313a, 313b, 413, 513a, 513b, 613, 713a, 713b: blue LED array

311, 511, 711: Red LED Array Group

312, 512, 712 green LED array

313, 513, 713: Blue LED Array Group

631, 632: LED Array Serial Connection

731, 732: LED array group series connection structure

220, 320, 420, 520, 620, 720: LED driver

221, 321, 421, 521, 621, 721: red LED driving circuit

222, 322, 422, 522, 622, 722: green LED driving circuit

223, 323, 423, 523, 623, 723: blue LED driving circuit

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a backlight unit used in a liquid crystal display (LCD) using a light emitting diode (LED), and more particularly, to a plurality of LEDs used for a surface light source in an electrical connection structure in which a series and a parallel are appropriately mixed. The present invention relates to a backlight unit using an LED that improves the efficiency of driving the LED by connecting and driving a plurality of LEDs emitting the same color by using one driving circuit.

Cold Cathode Fluorescent Lamp (CCFL) used as a light source of the existing LCD backlight unit uses mercury gas, which can cause environmental pollution, slow response speed, low color reproducibility, and light and thin edge of LCD panel. It has disadvantages that are not appropriate for digestion. In contrast, LEDs are environmentally friendly and have fast response times of several nanoseconds, making them effective for video signal streams and enabling impulsive driving. In addition, the color reproducibility is 100% or more, and the brightness, color temperature, and the like can be arbitrarily changed by adjusting the light amounts of the red, green, and blue LEDs. In addition, the LED light source is suitable for thin and light reduction of the LCD panel. Due to these advantages, LED has been actively adopted as a light source for backlights such as LCD panels.

In general, a backlight unit employing an LED may be classified into an edge type backlight unit and a direct type backlight unit according to a position of a light source. The edge type backlight unit adopts a method in which a bar-shaped light source having a long horizontal length is disposed on the side of the light guide plate and irradiates light to the front of the LCD panel through the light guide plate. The direct backlight unit is disposed directly under the LCD panel and adopts a method of irradiating light directly to the front of the LCD panel from a surface light source having almost the same area as the LCD panel.

1 is a configuration diagram showing an example of a conventional direct type LCD backlight unit.

Referring to FIG. 1, the conventional direct backlight unit 100 includes a plurality of LED modules 110 having a plurality of red, blue, and green LEDs. In the present specification, the term 'red LED' refers to an LED emitting red light, the term 'green LED' refers to an LED emitting green light, and the term 'blue LED' refers to an LED emitting blue light.

LEDs emitting the same color in one LED module 110 are connected to each other in series connection structure (111, 112, 113), each of the LEDs connected in series with each other of the corresponding color LED driving circuit of the LED driver 120 ( 121, 122, and 123 receive driving current and emit light.

In the conventional backlight unit as described above, three driving circuits for driving red, green, and blue LEDs are required for each LED module. Therefore, as the number of LED modules increases, the number of driving circuits for driving LEDs also increases. For example, when the number of LED modules is n, as many as 3 x n LED driving circuits were required.

The LCD backlight unit 100 using such a conventional LED requires a large number of driving circuits because the LED driving unit 120 should be provided for each LED module 110. As a result, the number of electrical and electronic components constituting the driving circuit increases, which causes a problem of increasing the production cost of the backlight unit. In addition, since the driving current for driving the LED of the LED module is individually generated in each driving circuit, the size of the driving current provided to the LED is different for each LED module, and thus the light generated in each LED module is uneven. This may cause a problem of deteriorating the image quality of the LCD panel.

The present invention is to solve the above-described problems of the prior art, by reducing the number of electrical and electronic components and the size of the drive board is implemented by the common use of the drive circuit that the LED in the plurality of LED modules provide a drive current. The purpose of the present invention is to provide a backlight unit using an LED that can provide uniform driving current to a plurality of LED modules, thereby achieving uniform light emission between the LED modules and thereby improving the image quality of the LCD screen.

In order to achieve the above technical problem, the present invention,

A plurality of LED modules including a plurality of red LEDs electrically connected to each other, a plurality of green LEDs electrically connected to each other, and a plurality of blue LEDs electrically connected to each other; A red LED driving circuit which drives a plurality of red LEDs included in the plurality of LED modules in common, a green LED driving circuit which drives a plurality of green LEDs included in the plurality of LED modules in common, and the plurality of LED modules An LED driver including a blue LED driving circuit for driving a plurality of blue LEDs included in common, wherein a plurality of red LED, green LED and blue LED included in each LED module is electrically connected to each other between the LED of the same color It provides a backlight unit using an LED, characterized in that formed.

Preferably, the LED module may include a red LED array in which the plurality of red LEDs are connected in series to each other, a green LED array in which the plurality of green LEDs are connected in series with each other, and a blue LED array in which the plurality of blue LEDs are connected in series with each other. have.

In one embodiment of the invention, the red, green and blue LED arrays in the LED module may be connected in parallel with each other with the red, green and blue LED arrays in the other LED module. In addition, the red, green and blue LED arrays in the LED module may be connected in series with each other with the red, green and blue LED arrays in the other LED modules. In addition, the red, green and blue LED arrays in at least two or more LED modules of the plurality of LED modules are connected to each other in series to form a plurality of red, green and blue LED array series connection structure, respectively, the red, green and blue LED The array serial connection structure may be connected in parallel with each other with the other red, green and blue LED array serial connection structures.

In another embodiment of the present invention, the LED module is a red LED array group in which the red LED array is connected in parallel to each other, a green LED array group in which the green LED array is connected in parallel to each other and a blue LED array in which the blue LED array is connected in parallel to each other. It can include a group. In addition, the red, green, and blue LED array groups in the LED module may be connected to each other in parallel with the red, green, and blue LED array groups in the other LED modules. In addition, the red, green, and blue LED array groups in the LED module may be connected to each other in series with the red, green, and blue LED array groups in the other LED modules. In addition, the red, green and blue LED array group in at least two or more LED modules of the plurality of LED modules are connected in series with each other to form a plurality of red, green and blue LED array group series connection structure, respectively, the red, green and The blue LED array group series connection structure may be connected in parallel with each other with the other red, green and blue LED array group series structures.

Hereinafter, various embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, embodiments of the present invention may be modified in various other forms, and the scope of the present invention is not limited to the embodiments described below. Embodiments of the present invention are provided to more completely explain the present invention to those skilled in the art. Therefore, the shape and size of the components shown in the drawings may be exaggerated for more clear description, components having substantially the same configuration and function in the drawings will use the same reference numerals.

2 to 7 are diagrams illustrating a backlight unit using an LED according to various embodiments of the present disclosure.

First, the backlight unit 200 using the LED according to the embodiment illustrated in FIG. 2 includes a plurality of LED modules 210 including a plurality of red, green, and blue LEDs, and a plurality of LED modules included in the plurality of LED modules. It consists of one LED driver 220 for driving the red, green, blue LED.

The LED module 210 is a unit that can be employed as a surface light source having a certain area by itself by generating a white light including a plurality of red, green and blue LEDs, and a submount such as a substrate It may include a plurality of red, green and blue LEDs disposed. The red, green, and blue LEDs disposed in the LED module may be connected to each other by various electrical connection structures between LEDs of the same color.

In addition, in this embodiment, the plurality of red, green, and blue LEDs included in each of the LED modules 210 may include the red LED array 211, the green LED array 212, and the blue LED in which LEDs of the same color are connected in series. The array 213 is formed. In the present specification, the term 'LED array' will be defined as a structure in which LEDs of the same color are connected in series with each other.

The arrangement of the LEDs shown in the LED module 210 of FIG. 2 is for explaining the electrical connection structure, and the LEDs arranged on the submount of the actual LED module 210 have various forms of arrangement for forming uniform white light. It may have a structure.

In this embodiment, the red, green, and blue LED arrays 211, 212, 213 in the LED module 210 are combined with the red, green, and blue LED arrays 211, 212, 213 in the other LED module 210. Each can be connected in parallel to each other. That is, in this embodiment, the red, green, and blue LEDs in each LED module 210 form an LED array in which the LEDs of the same color are connected in series, and the LED arrays included in the different LED modules display the LEDs of the same color. Included LED arrays have an overall connection structure connected in parallel with each other.

The LED driver 220 includes one red LED driving circuit 221 for driving all red LED arrays 211 included in the plurality of LED modules 210 and all greens included in the plurality of LED modules 210. One green LED driving circuit 222 for driving the LED array 212 and one blue LED driving circuit 223 for driving the entire blue LED array 213 included in the plurality of LED modules 210. It is configured to include. That is, the red, green, and blue LED arrays 211, 212, and 213 included in each LED module 210 may be driven by one red, green, and blue LED driving circuit in common.

As in the present exemplary embodiment, the red, green, and blue LED arrays 211, 212, and 213 included in each of the plurality of LED modules 210 have one connection structure as a whole, and each of the red, green, and Since the red, green, and blue LEDs have one connection structure in the blue LED arrays 211, 212, and 213, all the red, green, and blue colors included in the backlight unit 200 by one LED driver 210 are included. The LED can be driven.

Therefore, according to the present embodiment, the total number of driving circuits can be reduced as compared with the conventional backlight unit for driving LEDs having respective driving units for each LED module, thereby reducing the complexity of the design of the overall backlight unit. In addition, the number of electrical and electronic components required for the backlight unit can be reduced.

Next, the backlight unit 300 using the LED according to the embodiment shown in FIG. 3 includes a plurality of LED modules 310 and an LED driver for driving the LEDs included in the plurality of LED modules 310 in common. 320).

In this embodiment, each of the plurality of LED modules 310 includes a plurality of red LED arrays 311a and 311b having a plurality of red LEDs connected in series with each other, and a plurality of green LED arrays 312a having a plurality of green LEDs connected with each other in series. 312b) and a plurality of blue LED arrays 313a and 313b connected in series with each other. Within each LED module 310, the plurality of red LED arrays 311a and 311b are connected in parallel to each other to form a red LED array group 311, and the plurality of green LED arrays 312a and 312b are parallel to each other. Are connected to form a green LED array group 312, and the plurality of blue LED arrays 313a and 313b are connected in parallel to each other to form a blue LED array group 313. In FIG. 3, the two LED arrays of each color are connected in parallel to each other to form an LED array group. However, all structures in which two or more LED arrays are connected in parallel to each other are considered to be included in the scope of the LED array group of the present invention. Could be.

In this embodiment, the red, green, and blue LED array groups 311, 312, 313 in the LED module 310 are the red, green, and blue LED array groups 311, 312, 313 in the other LED modules 310. ) Can be connected in parallel with each other. That is, in the present embodiment, the red, green, and blue LEDs in each LED module 310 form a plurality of LED arrays in which LEDs of the same color are connected in series with each other, and the plurality of LED arrays are again connected in parallel with each other. To form. In addition, the LED array groups included in different LED modules have an overall connection structure connected in parallel with the LED array groups including the LED of the same color.

The LED driver 320 includes one red LED driving circuit 321 for driving all of the red LED array groups 311 included in the plurality of LED modules 310 and all of the plurality of LED modules 310. One green LED driving circuit 322 for driving the green LED array group 312 and one blue LED driving circuit for driving the entire blue LED array 313 included in the plurality of LED modules 310 ( 323). That is, the red, green, and blue LED array groups 311, 312, and 313 included in each LED module 310 may be driven by one red, green, and blue LED driving circuit in common. As a result, as in the embodiment shown in FIG. 2, the size of the driving circuit and the number of electronic components used therein can be reduced.

In general, an LED may emit light when an appropriate voltage is applied to both electrodes of the LED. When a plurality of LEDs are connected in series, the LEDs are multiplied by the number of LEDs connected in series by an appropriate voltage required for an individual LED. The voltage must be applied to the entire series of LEDs to emit light. Therefore, when the number of LED modules used in the backlight unit and the number of LEDs for each color in each LED module are the same, the embodiment shown in FIG. 3 (an embodiment in which two LED arrays form one LED array group) is shown in FIG. Since the number of LEDs connected in series is reduced by half compared to the embodiment shown in Fig. 2, the backlight unit of the embodiment shown in Fig. 3 drives 0.5 times the driving voltage to drive each color LED as compared to the backlight unit shown in Fig. The LED drive circuit can be designed to supply only. Instead of reducing the driving voltage by 0.5 times, the same power must be supplied to obtain the same brightness, so the backlight unit shown in FIG. 3 should be designed to supply twice the driving current as compared to the backlight unit shown in FIG. .

Next, the backlight unit 400 using the LED according to the embodiment shown in FIG. 4 includes an LED module 410 and an LED driver 420 having the same LED connection structure as shown in FIG. 2.

The backlight unit 400 according to this embodiment includes a red LED array 411, a green LED array 412, and a blue LED array 413 in the LED module 410. 411, green LED array 412, and blue LED array 413 are each connected in series with each other. The red, green, and blue LED arrays in each LED module connected in series with each other are driven by the red, green, and blue LED driving circuits 421, 422, and 423 of the LED driver 420, respectively.

In this embodiment, the LED arrays in each LED module are connected in series by the number of LED modules. Therefore, when the number of LED modules used in the backlight unit and the number of LEDs for each color in each LED module are the same, assuming that the number of LED modules used in the backlight unit is n, the LED driving circuit of the backlight unit shown in FIG. 421, 422, and 423 form a structure in which n times as many LEDs are connected in series as the LED driving circuit shown in FIG. Therefore, the LED driving circuit of the backlight unit shown in FIG. 4 may be designed to supply n times the driving voltage compared to the LED driving circuit of the backlight unit shown in FIG. 2, and in order to obtain the same amount of light, It must be designed to supply the drive current.

Next, the backlight unit 500 using the LED according to the exemplary embodiment illustrated in FIG. 5 includes an LED module 510 and an LED driver 520 having the same LED connection structure as illustrated in FIG. 3.

In the backlight unit 500 according to this embodiment, the LED module 510 includes a plurality of red LED arrays 511a and 511b having red LEDs connected in series with each other, and a plurality of green LED arrays 512a with green LEDs connected in series with each other. 512b and a plurality of blue LED arrays 513a and 513b in which blue LEDs are connected to each other in series. In addition, the plurality of red LED arrays 511a and 511b are connected in parallel to each other to form a red LED array group 511, and the green LED arrays 512a and 512b are connected to each other in parallel to the green LED array group 512. ) And the blue LED arrays 513a and 513b are connected in parallel to each other to form a blue LED array group 513.

The red LED array group 511, the green LED array group 512, and the blue LED array group 513 are a red LED array group 511, a green LED array group 512, and a blue LED in another LED module 410. The array group 513 is connected in series with each other. The red, green, and blue LED array groups in each LED module connected in series with each other are driven by the red, green, and blue LED driving circuits 421, 422, and 423 of the LED driver 420, respectively.

In the backlight unit according to this embodiment, the LED array group is connected in series by the number of LED modules, and the LEDs connected in series to one LED array when the number of LED modules used in the backlight unit and the number of LEDs for each color in each LED module are the same. The number of times is 1/2 of the number of red LEDs connected in series to one LED array shown in FIG. 2. Therefore, if the number of LED modules is n, one LED driving circuit in the embodiment shown in FIG. 5 can be designed to supply n / 2 times the driving voltage than one LED driving circuit shown in FIG. In order to provide the same power, it may be designed to supply 2 / n times the driving current compared to the one LED driving circuit shown in FIG.

Next, the backlight unit 600 using the LED according to the embodiment shown in FIG. 6 includes an LED module 610 and an LED driver 620 having the same LED connection structure as that shown in FIG. 2. . FIG. 6 shows only one color LED array (for example, red LED array 611) for convenience of description, and omits other color LED arrays. However, the LED module 610 should be considered to include a green LED array and a blue LED array, and the connection will be understood to have the same connection as described below.

In this embodiment, the LEDs of each color included in each LED module 610 form an LED array 611 in which the same colors are connected in series with each other. The LED array 611 is connected to each other in series with the LED array of the same color included in at least one other LED module to form the LED array serial connection structure (631, 632). At least two of the LED array series connection structures 631 and 632 are formed, and the plurality of LED array series connection structures 631 and 632 are connected in parallel to each other to the corresponding color LED driving circuit 621 of the LED driver 620. Driven by.

As shown in FIG. 6, when the present embodiment includes two LED array series connection structures 631 and 632, the embodiment shown in FIG. 2 is compared with the embodiment shown in FIG. 6 as follows. . First, assuming that the number of LED modules in the LED module of the embodiment shown in FIG. 2 and the embodiment shown in FIG. 6 is the same, the number of LEDs connected in series to the LED array of the embodiment shown in FIG. If the number of LEDs connected in series in the LED array of the embodiment shown in FIG. 2 is the same, and in the embodiment of FIG. 6, the LED arrays are connected to each other in series by half, the number of the LED modules is n. The LED driving circuit of the illustrated embodiment can be designed to supply n / 2 times the driving voltage than the LED driving circuit shown in FIG. 2, and to supply 2 / n times the driving current to supply the same power. Can be designed.

Next, the backlight unit 700 using the LED according to the embodiment shown in FIG. 7 includes an LED module 710 and an LED driver 720 having the same LED connection structure as shown in FIG. 3. As in FIG. 6, FIG. 7 illustrates only one color LED array group (for example, a red LED array group 711) for convenience of description, and omits another color LED array group. However, the LED module 710 should be regarded as including the green LED array group and the blue LED array group, and the connection relationship will be understood to have the same connection relationship as described below.

In this embodiment, the LEDs of each color included in each LED module 710 form LED arrays 711a and 711b of the same color connected in series with each other, and the LED arrays 711a and 711b are connected to each other in parallel to the LED array. Group 711 is formed. The LED array group 711 is connected in series with the LED array group of the same color included in at least one other LED module to form the LED array group serial connection structure (731, 732). At least two LED array group serial connection structures 731 and 732 are formed, and a plurality of LED array group serial connection structures 731 and 732 are connected in parallel to each other so that a corresponding color LED driving circuit 721 of the LED driver 720 is provided. Driven by).

As shown in FIG. 7, the embodiment shown in FIG. 2 has an LED array group having two LED arrays, and includes two LED array group series connection structures 731 and 732. Comparing the embodiment shown in Figure 6 as follows. First, assuming that the number of LEDs in the LED module and the LED module of the embodiment shown in FIG. 2 and the embodiment shown in FIG. 7 is the same, the number of LEDs connected in series to the LED array of the embodiment shown in FIG. If the number of LEDs connected in series in the LED array of the embodiment shown in FIG. 2 is 1/2, and in the embodiment of FIG. 7, the LED array groups are connected to each other in series by half, the number of LED modules is n. The LED driving circuit of the embodiment shown in FIG. 7 may be designed to supply n / 4 times the driving voltage than the LED driving circuit shown in FIG. 2, and 4 / n times the driving current to provide the same power. It can be designed to supply.

As described above, according to the present invention, by driving the LED using one driving circuit for each color, the driving circuit is simplified to simplify the design and reduce the number of parts to provide a more economical LCD backlight unit using the LED It works.

In addition, since the number of driving circuits is reduced to three, the size of the driving board provided with the driving circuit is reduced, thereby reducing the overall size of the product, thereby contributing to the slimming of the product.

In addition, since the driving circuit is simplified and the LEDs of the same color are driven by one driving circuit, the LEDs of the same color are simultaneously controlled to improve the image quality.

Claims (9)

A plurality of LED modules including a plurality of red LEDs electrically connected to each other, a plurality of green LEDs electrically connected to each other, and a plurality of blue LEDs electrically connected to each other; A red LED driving circuit which drives a plurality of red LEDs included in the plurality of LED modules in common, a green LED driving circuit which drives a plurality of green LEDs included in the plurality of LED modules in common, and the plurality of LED modules An LED driver including a blue LED driving circuit for driving a plurality of blue LEDs included in common, And a plurality of red LEDs, green LEDs, and blue LEDs included in each of the LED modules form an electrical connection between the LEDs of the same color. The method of claim 1, wherein the LED module, And a red LED array in which the plurality of red LEDs are connected in series, a green LED array in which the plurality of green LEDs are connected in series, and a blue LED array in which the plurality of blue LEDs are connected in series. . The method of claim 2, The red, green and blue LED array in the LED module, the backlight unit using an LED, characterized in that connected to each other in parallel with the red, green and blue LED array in another LED module. The method of claim 2, The red, green and blue LED array in the LED module, the backlight unit using an LED, characterized in that each connected in series with the red, green and blue LED array in another LED module. The method of claim 2, The red, green and blue LED arrays in at least two or more LED modules of the plurality of LED modules are connected in series to each other to form a plurality of red, green and blue LED array series connection structures, and the red, green and blue LED array series Connection structure is a backlight unit using the LED, characterized in that connected in parallel with each other, red, green and blue LED array series connection structure. The method of claim 2, wherein the LED module, And a red LED array group in which the red LED arrays are connected in parallel to each other, a green LED array group in which the green LED arrays are connected in parallel to each other, and a blue LED array group in which the blue LED arrays are connected in parallel to each other. . The method of claim 6, The red, green and blue LED array group in the LED module, the backlight unit using an LED, characterized in that connected to each other in parallel with the red, green and blue LED array group in the other LED module. The method of claim 6, And a red, green, and blue LED array group in the LED module is connected to each other in series with the red, green, and blue LED array group in another LED module. The method of claim 6, The red, green, and blue LED array groups in at least two or more LED modules of the plurality of LED modules are connected in series to each other to form a plurality of red, green, and blue LED array group series connection structures, and the red, green, and blue LEDs The array group series connection structure is a backlight unit using the LED, characterized in that connected to each other in parallel with each other, red, green and blue LED array group series connection structure.

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