KR102124905B1 - Backlight unit and liquid crystal display device including the same - Google Patents

Abstract

The present invention relates to a backlight unit and a liquid crystal display device including the same.
The liquid crystal display according to the present invention includes a liquid crystal panel, a plurality of LEDs, a backlight including a LED assembly disposed under the liquid crystal panel and a reflector reflecting light emitted from each of the plurality of LEDs toward the liquid crystal panel. It includes a unit, the reflecting plate is characterized in that it has a light pattern that protrudes from the inner surface and the center portion thereof is gradually narrowed.
Through this, the total number of LEDs is reduced, and a liquid crystal display device having light weight and competitive price can be realized.

Description

Backlight unit and liquid crystal display device including the same{BACKLIGHT UNIT AND LIQUID CRYSTAL DISPLAY DEVICE INCLUDING THE SAME}

The present invention relates to a backlight unit and a liquid crystal display device including the same, and more particularly, to a backlight unit capable of reducing the number of LEDs and a liquid crystal display device including the same.

The liquid crystal display device (LCD), which is actively used in TVs, monitors, etc. because it is advantageous for moving picture display and has a large contrast ratio, is an optical anisotropy and polarization of liquid crystal. It shows the principle of image implementation.

This liquid crystal display device is a liquid crystal panel (liquid crystal panel) interposed between the two substrates (substrate) interposed between the liquid crystal panel (liquid crystal panel) as an essential component, the electric field in the liquid crystal panel to change the arrangement direction of the liquid crystal molecules to realize the difference in transmittance do.

However, since the liquid crystal panel does not have a light emitting element, a separate light source is required to display a difference in transmittance as an image. To this end, a backlight unit having a light source is disposed on the rear surface of the liquid crystal panel.

Here, as a light source of the backlight unit, a cold cathode fluorescent lamp (Cold Cathode Fluorescent Lamp: CCFL) or an external electrode fluorescent lamp (External Electrode Fluorescent Lamp: EEFL) has been used a lot of fluorescent lamps, but recently, the thinning of the liquid crystal display device, Light emitting diodes (LEDs), which have advantages in power consumption, weight, and luminance, are replacing fluorescent lamps in accordance with the trend of weight reduction.

According to the position of the light source, the backlight unit can be divided into a direct type and an edge type. In the direct type backlight unit, the light emitted from the light source is directly disposed by placing the light source under the liquid crystal panel. A method of supplying to a liquid crystal panel, and a backlight unit of a side type method indirectly injects light emitted from a light source by using refraction and reflection in the light guide plate by arranging the light guide plate under the liquid crystal panel and placing the light source on at least one side of the light guide plate. It is a method of supplying to a liquid crystal panel.

At this time, the direct-type backlight unit requires a larger number of light sources than the side-type backlight unit as the light source is disposed under the liquid crystal panel.

On the other hand, recently, the liquid crystal display device has a wide display area as the use area of the portable computer as well as the desktop computer monitor and the wall-mounted TV is diversified, and at the same time, a study to implement a liquid crystal display device that is lightweight, thin and relatively inexpensive. In the case of the direct type liquid crystal display device, the number of LEDs included increases as the display area increases, and thus, there is a problem in light weight and difficulty in terms of price.

An object of the present invention for solving the above problems is to provide a backlight unit capable of reducing the total number of LEDs and a liquid crystal display device including the same.

A liquid crystal display device according to the present invention for achieving the above object, a liquid crystal panel; And a backlight unit including a plurality of LEDs and an LED assembly disposed under the liquid crystal panel and a reflector reflecting light emitted from each of the plurality of LEDs toward the liquid crystal panel, the reflector protruding from an inner surface. It is characterized in that the central portion is provided with an optical pattern that gradually becomes narrower.

The light pattern is characterized in that it is located in the center of the LED through hole located in all directions.

The light pattern is characterized in that it has a conical shape or a pyramid shape with side surfaces made of polyhedra.

The side surface of the paramid shape is characterized in that it is a curved surface having a curvature.

It characterized in that the coupling hole is provided at the end of the optical pattern.

The backlight unit further includes a support pin coupled to the coupling hole and a diffusion plate positioned above the reflection plate, wherein the diffusion plate maintains a constant optical gap with the reflection plate through the support pin. It is characterized by.

Further comprising a diffusion plate positioned on top of the reflector, the diffusion plate is characterized in that to maintain a constant optical gap with the reflector through the light pattern.

On the other hand, the backlight unit according to the present invention includes an LED assembly including a plurality of LEDs; It reflects the light emitted from each of the plurality of LEDs toward the front direction, and includes a reflector having a light pattern protruding from the inner surface, wherein the light pattern is characterized in that the center portion becomes narrower toward the end.

The light pattern is characterized in that it is located in the center of the LED through hole located in all directions.

The light pattern is characterized in that it has a conical shape or a pyramid shape with side surfaces made of polyhedra.

The side surface of the paramid shape is characterized in that it is a curved surface having a curvature.

It characterized in that the coupling hole is provided at the end of the optical pattern.

It further comprises a support pin coupled to the coupling hole, and a diffusion plate positioned above the reflection plate, wherein the diffusion plate maintains a constant optical gap with the reflection plate through the support pin.

Further comprising a diffusion plate positioned on top of the reflector, the diffusion plate is characterized in that to maintain a constant optical gap with the reflector through the light pattern.

As described above, according to the backlight unit and the liquid crystal display device including the same according to the present invention, the light pattern of the reflector is located between the plurality of LED through holes, so that the luminance of the overlapping regions where the light overlaps by the adjacent LEDs is overlapped As it increases, the overlapping area can be widened.

Through this, it is possible to reduce the total number of LEDs by not only increasing the separation distance between multiple LEDs, but also increasing the separation distance between multiple LED assemblies.

Furthermore, it is possible to reduce the manufacturing cost of the entire liquid crystal display device by reducing the cost of the LED component, and to realize a lightweight liquid crystal display device.

In addition, there is an advantage that it is possible to omit the support pin capable of maintaining a constant optical gap between the reflector and the diffusion plate.

1 is an exploded perspective view showing a liquid crystal display device according to a preferred embodiment of the present invention.
2 is a cross-sectional view showing a liquid crystal display device according to a preferred embodiment of the present invention.
3 is a perspective view showing a reflector according to a preferred embodiment of the present invention.
4 is a view for explaining a light path in the backlight unit according to a preferred embodiment of the present invention.
5 is a cross-sectional view showing a liquid crystal display device according to another embodiment of the present invention.
6 is a view showing another example of a light pattern formed on a reflector according to an embodiment of the present invention.

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

1 is an exploded perspective view showing a liquid crystal display device according to a preferred embodiment of the present invention, and FIG. 2 is a cross-sectional view showing a liquid crystal display device according to a preferred embodiment of the present invention.

As illustrated, the liquid crystal display device 100 according to the present invention includes a liquid crystal panel 110, a backlight unit 120, and a support main 130 for modularizing the liquid crystal panel 110 and the backlight unit 120. And a top cover 140 and a cover bottom 150.

The liquid crystal panel 110 is a part that plays a key role in image expression, and is composed of first and second substrates 112 and 114 bonded to each other with a liquid crystal layer interposed therebetween.

Here, although not shown in the drawing, a plurality of gate lines and data lines are intersected and pixels are defined on the inner surface of the first substrate 112 commonly referred to as a lower substrate or an array substrate under the premise of an active matrix method, and each intersection point A thin film transistor (TFT) is provided to be connected one-to-one to a transparent pixel electrode formed in each pixel.

In addition, as an example corresponding to each pixel on the inner surface of the second substrate 114 called an upper substrate or a color substrate, color filters of red (R), green (G), and blue (B) colors, and these A black matrix is provided to cover non-display elements such as a gate line, a data line, and a thin film transistor.

In addition, a transparent common electrode corresponding to the pixel electrode may be provided on the first substrate 112 or the second substrate 114.

In addition, first and second polarizing plates 119a and 119b selectively transmitting only specific light are attached to the outer surfaces of the first and second substrates 112 and 114, respectively.

In addition, the driving printed circuit board 117 is connected and modularized through a connecting member 116 such as a flexible circuit board or a tape carrier package (TCP) along at least one edge of the liquid crystal panel 110. In the process, the side of the support main 130 or the back surface of the cover bottom 150 can be properly flipped to close.

Accordingly, when the thin film transistor selected for each gate line is turned on by the on or off signal of the gate driving circuit transmitted through the driving printed circuit board 117, the liquid crystal panel 110 having the above-described structure is turned on. The signal voltage is transmitted to the corresponding pixel electrode through the data line, and accordingly, the arrangement direction of the liquid crystal molecules is changed by the electric field between the pixel electrode and the common electrode, thereby indicating a difference in transmittance.

On the rear surface of the liquid crystal panel 110, a backlight unit 120 is provided to supply light to display a difference in transmittance as an image.

The backlight unit 120 includes a plurality of LED assemblies 129, a reflector plate 127 positioned on the plurality of LED assemblies 129, a diffuser plate 124 positioned above the reflector plate 127, and a reflector plate ( 127) and a support pin 128 positioned between the diffuser plate 124 and an optical sheet 121 positioned above the diffuser plate 124.

Each of the plurality of LED assemblies 129 is made by being mounted on the LED Printed Circuit Board (PCB) 129b with a plurality of LEDs 129a spaced apart at regular intervals.

Each of the plurality of LEDs 129a includes an LED lens for refracting and reflecting light generated from an LED chip that emits light.

At this time, the LED lens may be a refractive LED lens that double-refracts the light generated from the LED chip so that all light is directed to the liquid crystal panel 110.

Alternatively, the LED lens may be a reflective LED lens that refracts and totally reflects light generated from the LED chip so that some light is directed toward the liquid crystal panel 110 and some light is directed toward the cover bottom 150.

At this time, since the LED 129a to which the reflective LED lens is applied has a wider light directing angle than the LED to which the refractive LED lens to which all of the light is directed toward the liquid crystal panel 110 is applied, the spacing between the plurality of LEDs 129a is increased. It is wider and allows fewer LEDs 129a to be used. In addition, it is possible to use a smaller number of LEDs 129a by widening the spacing between the LED assemblies 129 as well as the spacing between the LEDs 129a.

The plurality of LED assemblies 129 may be arranged side by side along the long direction of the cover bottom 150, or may be arranged side by side along a unidirectional direction perpendicular to the long direction.

Meanwhile, the LED printed circuit board 129b in which a plurality of LEDs 129a are mounted may correspond to a metal core printed circuit board having a heat dissipation function, and the rear surface of the metal core printed circuit board. The heat sink (not shown) is provided to allow heat generated from each of the plurality of LEDs 129a to be discharged to the outside.

The upper portion of the LED printed circuit board 129b is a reflector 127 that reflects some of the light emitted from each of the plurality of LEDs 129a toward the cover bottom 150 toward the liquid crystal panel 110.

The reflector 127 is a first part 125 including a plurality of LED through-holes 125a and a plurality of light patterns 125b, and a first part 125 that is inclined in an outward direction along the edge of the first part 125 It consists of two parts 126.

Here, the plurality of LED through holes 125a corresponds to each of the plurality of LEDs 129a included in the plurality of LED assemblies 129, and is a hole through which each of the plurality of LEDs 129a can pass.

Each of the plurality of LEDs 129a is passed through and exposed through the plurality of LED through holes 125a, so that the reflector 127 is seated on the top of the LED printed circuit board 129b.

The plurality of light patterns 125b is a pattern that serves to further increase the light emitted from each of the plurality of LEDs 129a.

Each of the plurality of light patterns 125b for this purpose protrudes from the inner surface of the first portion 125 of the reflector 127 and has a shape in which its central portion becomes narrower and includes a coupling hole 128a at its end. At this time, the coupling hole 128a may be formed on at least one of the plurality of light patterns 125b, for example, may be formed by skipping one or two.

The plurality of light patterns 125b are positioned between the LEDs 129a adjacent to each other, thereby increasing the luminance of the overlapping regions where light emitted from the adjacent LEDs 129a overlaps (overlaps) and enlarges the overlapping region. . Therefore, the spacing between the plurality of LEDs is widened and the number of LEDs can be reduced. This will be described in detail later.

A diffusion plate 124 for diffusing light is positioned on the upper portion of the reflective plate 127 having the above-described structure with the optical gap G interposed therebetween.

The optical gap G is an interval required to diffuse light emitted from each of the plurality of LEDs 129a to form light uniformity.

In order to keep the optical gap G constant, a plurality of support pins 128 are provided between the reflection plate 127 and the diffusion plate 124, and the plurality of support pins 128 are optical patterns on the reflection plate 127. It is positioned between the reflector 127 and the diffuser plate 124 in a state coupled through the end coupling hole 128a of the 125b.

On the other hand, when the above-described plurality of LEDs 129a are applied as reflective LEDs, there is an advantage of reducing the optical gap G between the reflector 127 and the diffuser plate 124 because the light directing angle is wide. Through this, it is possible to reduce the overall thickness of the liquid crystal display device 100.

An optical sheet 121 is positioned above the diffusion plate 124.

Here, the optical sheet 121 may include at least a diffusion sheet, at least one condensing sheet, and a protective sheet, and various functional sheets such as a dual brightness enhancement film called DBEF (dual brightness enhancement film) capable of increasing luminance. It can be included to increase the luminance of the light emitted from the plurality of LEDs (129a).

Accordingly, light emitted from each of the plurality of LEDs 129a is incident on the liquid crystal panel 110 by the reflector 127, the diffuser plate 124, and the optical sheet 121, and uses the liquid crystal panel 110 using the light. ) Displays a high-brightness image to the outside.

The liquid crystal panel 110 and the backlight unit 120 are modularized through the top cover 140, the support main 130, and the cover bottom 150.

Here, the top cover 140 is a rectangular frame shape in which a cross-section is bent in a shape to cover the top and side edges of the liquid crystal panel 110, and is implemented in the liquid crystal panel 110 by opening the front surface of the top cover 140. It is configured to display the image.

In addition, the cover bottom 150 on which the liquid crystal panel 110 and the backlight unit 120 are settled and which is the basis for assembling the entire apparatus of the liquid crystal display device 100 is a square plate shape of the cover bottom 150. It may include a pair of bar-shaped side support (not shown) coupled to the edge of both ends facing each other.

In addition, the other two edges of the cover bottom 150, except for the side support (not shown), are bent upward at an angle so as to have the same height as these, thereby forming a predetermined space in which the backlight unit 120 can be seated. .

Modularized by being mounted on the cover bottom 150 and supporting the main frame 130 having a rectangular frame shape surrounding the edges of the liquid crystal panel 110 and the backlight unit 120 with the top cover 140 and the cover bottom 150. Is made.

Meanwhile, the top cover 140 may be referred to as a case top or top case, the support main 130 may be referred to as a guide panel or main support, or a mold frame, and the cover bottom 150 may also be referred to as a bottom cover.

3 is a perspective view showing a reflector according to a preferred embodiment of the present invention, and FIG. 4 is a view for explaining a light traveling path in a backlight unit according to a preferred embodiment of the present invention, see FIGS. 1 and 2 do.

As illustrated, the reflector 127 includes a first portion 125 including a plurality of LED through holes 125a for exposing each of the plurality of LEDs 129a and an edge of the first portion 125. It is composed of a second portion 126 connected obliquely in the outward direction.

Here, a plurality of LEDs 129a exposed through the plurality of LED through holes 125a are positioned in the first portion 125, and an optical pattern 125b is further provided between the adjacent LED through holes 125a. .

The light pattern 125b is formed to protrude from the inner surface of the first portion 125, and is located in the center of four LED through holes 125a formed in all directions.

In this way, each of the plurality of LEDs 129a is affected by the four light patterns 125b formed in all directions by positioning the light patterns 125b.

In more detail, four light patterns 125b are positioned around each LED 129a. At this time, the light patterns 125b may be positioned at each corner of the rectangular area around the LED 129a.

For example, when the side of the light pattern 125b is made of a tetrahedron, the light emitted from the LED 129a is reflected through the side facing each other in each of the four light patterns 125b surrounding it.

Meanwhile, the present invention is not limited to the above, and the light pattern 125b is formed between the plurality of LED through holes 125a formed along the long direction of the first portion 125, that is, between the adjacent LED through holes 125a. It may be located, or may be located between a plurality of LED through holes 125a formed along one direction, that is, between adjacent LED through holes 125a.

The light pattern 125b may have various shapes, such as a conical shape protruding from the inner surface of the first portion 125 and gradually narrowing its central portion, or a pyramid shape having a polyhedron.

By providing the optical pattern 125b, the reach area of light emitted from each of the plurality of LEDs 129a is widened, and the overlapping areas where light generated from adjacent LEDs 129a are overlapped are widened.

Through this, since the separation distance between the plurality of LEDs 129a and the assembly between the plurality of LEDs 129a can be widened, the total number of LEDs 129a can be reduced. In this way, by reducing the number of parts of the LED, it is possible to reduce the cost and realize a lightweight liquid crystal display device.

The end of the optical pattern 125b includes a coupling hole 128a into which a support plate 128 for keeping the optical gap between the reflector 127 and the diffusion plate 124 constant can be inserted.

On the other hand, in the drawing, the end of the light pattern 125b is shown as being in a position higher than the upper surface of each of the plurality of LEDs 129a, but is not limited thereto, and may be configured not to protrude from the upper surface of each of the plurality of LEDs 129a. have. This may be advantageous for an LED having a reflective lens that emits some light in the rear direction toward the reflector 127.

The reflective plate 127 having such a structure is formed of a white or silver plate, for example, polyethylene terephthalate (PET), polyethylene naphthalate, polymethyl methacrylate (PMMA), It may be formed of one of polycarbonate (polycarbonate), polystyrene (polystyrene), polyolefin (polyolefine), cellulose acetate (cellulose acetate) and polyvinyl chloride (polyvinyl chloride).

The reflector 127 may be completed through a first process of forming a plurality of LED through holes 125a and a second process of forming a light pattern 125b by applying heat or pressure.

The light propagation path in the backlight unit 120 to which the reflector 127 as described above is applied will be described with reference to FIG. 4. Here, the configuration of the support pin is omitted in order to describe the light traveling direction in more detail.

As illustrated, light emitted from each of the plurality of LEDs 129a is emitted toward the first light L11 emitted toward the liquid crystal panel (110 of FIG. 2) and toward the light pattern 125b of the reflector 127. It can be divided into a second light (L21).

Accordingly, some light L12 of the first light L11 emitted from each of the plurality of LEDs 129a passes through the diffusion plate 124 and the optical sheet 121 and is provided to the liquid crystal panel (110 of FIG. 2 ). Some of the light L13 is re-reflected in the direction toward the liquid crystal panel (110 of FIG. 2) by the diffuse reflection plate 124 or the rear reflection plate 127 refracted (reflected) by the optical sheet 121.

In addition, the second light L21 emitted from each of the plurality of LEDs 129a is reflected L22 in the direction toward the liquid crystal panel (110 of FIG. 2) by the light pattern 125b of the reflector 127. Some light L23 of the reflected light L22 passes through the diffuser plate 124 and the optical sheet 121 and is provided to the liquid crystal panel (110 of FIG. 2), and some light L24 is diffuser plate 124 ) Or it is refracted (reflected) by the optical sheet 121 to face the reflector 127.

As described above, light emitted from each of the plurality of LEDs 129a is reflected by the light pattern 125b and emitted to the overlapping regions between the LEDs 129a, thereby increasing the luminance of the overlapping regions and making the overlapping regions wider. You can see that Through this, the spacing between the plurality of LEDs 129a and the separation between the plurality of LED assemblies 129 can be widened, and the total number of LEDs can be reduced.

Furthermore, by reducing the cost of LED components, it is possible to reduce the manufacturing cost of the entire liquid crystal display device and realize a lightweight liquid crystal display device.

On the other hand, in the case of an LED to which a reflective LED lens is applied, the light emitted from each of the plurality of LEDs 129a is the first light emitted toward the liquid crystal panel (110 of FIG. 2) and the light pattern 125b of the reflector 127 ) And the third light emitted toward the first portion 125 of the reflector 127. Here, some of the third light is reflected in the direction toward the light pattern 125b by the first portion 125 of the reflector 127, and some of the light is reflected in the direction toward the liquid crystal panel (110 in FIG. 2). Can be.

Also in this case, the light emitted from each of the plurality of LEDs 129a is reflected by the light pattern 125b and emitted to the overlapping region between the LEDs 129a, so that the luminance of the overlapping region increases and the overlapping region becomes wider. You can see that you can. Through this, the spacing between the plurality of LEDs 129a and the separation between the plurality of LED assemblies 129 can be widened, and the total number of LEDs can be reduced.

5 is a cross-sectional view showing a liquid crystal display device according to another exemplary embodiment of the present invention. Here, since the configuration except the configuration of the reflector and the support plate is the same as in FIGS. 2 and 3, detailed description of the same configuration will be omitted.

As illustrated, the reflector 227 includes a first portion 225 and a first portion 225 including a plurality of LED through holes 225a and a light pattern 225b exposing each of the plurality of LEDs 229a. It consists of a second portion 226 connected to have an obtuse angle along the edge of ).

Here, the light pattern 225b serves to increase the luminance of the overlapping regions where light emitted from the LEDs 229a adjacent to each other overlaps, and to expand the overlapping regions. In addition, the light pattern 225b serves to support the diffusion plate 224 by being formed to contact the diffusion plate 224 positioned on the upper portion.

Through this light pattern 225b, there is an advantage in that a plurality of support plates (128 of FIG. 2), which serve to maintain the optical gap G between the reflector 227 and the diffuser plate 224, can be omitted. .

6 is a view showing another example of a light pattern formed on a reflector according to an embodiment of the present invention.

As illustrated in FIG. 6, the light pattern 325b may have a pyramid shape composed of polyhedrons, wherein the side surface 310 composed of polyhedrons may be formed as a curved surface having a curvature.

Thus, by forming the side surface 30 of the light pattern 325b as a curved surface, light emitted from each of the plurality of LEDs (129a in FIG. 1) is more liquid crystal panel (Fig. 1) through the curved surface 310 of the light pattern 325b It can be bent in the direction toward 110).

For example, by making the curved surface 310 have a variable curvature, the direction of refraction of the incident light can be adjusted, and through this, the light distribution can be controlled.

The embodiments of the present invention as described above are only exemplary, and a person having ordinary skill in the art to which the present invention pertains can freely deform without departing from the spirit of the present invention. Accordingly, the protection scope of the present invention includes the appended claims and modifications of the present invention within the scope equivalent thereto.

100: liquid crystal display 110: liquid crystal panel
120: backlight unit 129: LED assembly
127, 227: reflector 125, 225: first part
125a, 225a: LED through hole 125b, 225b: light pattern
126, 226: Part 2 124: Diffusion plate
121: Optical sheet

Claims (15)

A liquid crystal panel;
A backlight unit including a LED assembly including a plurality of LEDs and disposed on a lower portion of the liquid crystal panel, a reflector reflecting light emitted from each of the plurality of LEDs toward the liquid crystal panel, and a diffuser disposed on the reflector. and;
An optical pattern formed on the reflector, protruding from the inner surface, the center portion thereof becoming narrower, and a coupling hole formed at an end;
And a support pin inserted into a coupling hole of the optical pattern and coupled with the optical pattern, and supporting the diffusion plate to maintain a constant optical gap between the reflection plate and the diffusion plate.
According to claim 1,
The light pattern is a liquid crystal display device, characterized in that located in the center of the LED through hole located in all directions.
According to claim 1,
The light pattern is a liquid crystal display device, characterized in that the pyramid shape of a conical shape or a side surface of a polyhedron. According to claim 3,
The side surface of the paramid shape is a liquid crystal display device, characterized in that the curved surface having a curvature.
delete delete delete An LED assembly including a plurality of LEDs;
A reflector reflecting light emitted from each of the plurality of LEDs toward the front direction and having a light pattern protruding from an inner surface;
A diffusion plate disposed on the reflective plate;
An optical pattern formed on the reflector, protruding from the inner surface, the center portion thereof becoming narrower, and a coupling hole formed at an end;
And a support pin inserted into a coupling hole of the optical pattern and coupled with the optical pattern, and supporting the diffusion plate to maintain a constant optical gap between the reflection plate and the diffusion plate.
The method of claim 8,
The light pattern is a backlight unit, characterized in that located in the center of the LED through hole located in all directions.
The method of claim 8,
The light pattern is a backlight unit, characterized in that the pyramid shape of a conical shape or a side surface of a polyhedron.
The method of claim 10,
The side surface of the paramid shape is a backlight unit characterized in that the curved surface having a curvature.
The method of claim 10,
A backlight unit, characterized in that a coupling hole is provided at an end of the light pattern.
delete delete According to claim 1,
The optical pattern is a liquid crystal display device, characterized in that located between a plurality of LED through-holes arranged along one direction.

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