KR20080106719A - Optical film having a plurality of structures, backlight unit including the same and method of manufacturing thereof - Google Patents

Abstract

An optical film is provided to increase the collection efficiency and improve luminance by forming the structure of the lens shape between the structures. An optical film including a plurality of structures includes a face on which is formed by a plurality of structures(420) and a smooth direction facing the structured side. A structure includes a plurality of a first structure(422) having the cross section of the triangle form and the second structure of the plurality having the cross section of the lens shape(424). A plurality of a second structure having the cross section of the lens shape while being installed in longitudinal direction of the first structure and between first structures.

Description

TECHNICAL FILM HAVING A PLURALITY OF STRUCTURES, BACKLIGHT UNIT INCLUDING THE SAME AND METHOD OF MANUFACTURING THEREOF

1 is a cross-sectional view showing the structure of a conventional prism sheet.

FIG. 2 is a diagram illustrating a distribution of light passing through the prism sheet of FIG. 1.

3 is a perspective view illustrating a liquid crystal display device using an edge-light backlight unit according to an exemplary embodiment of the present invention.

4 is a cross-sectional view illustrating the liquid crystal display panel of FIG. 3.

5 is a cross-sectional view illustrating a backlight unit of a direct type according to another embodiment of the present invention.

6a and 6b are a perspective view and a cross-sectional view schematically showing the structure of an optical film according to an embodiment of the present invention.

7 to 9 are perspective views schematically showing the structure of an optical film according to another embodiment of the present invention.

10 is a cross-sectional view schematically showing the structure of an optical film according to another embodiment of the present invention.

11A to 11E are views illustrating a method of manufacturing an optical film according to an exemplary embodiment of the present invention.

12A to 12E are views illustrating a method of manufacturing an optical film according to another embodiment of the present invention.

The present invention relates to an optical film including a plurality of structures, a backlight unit including the same, and a method of manufacturing the optical film.

In general, a liquid crystal display device (hereinafter referred to as an "LCD device") is an electronic device that transmits various electrical information generated by various devices to visual information by using a change in liquid crystal transmittance according to an applied voltage. Element.

Since the LCD element is a display element of various information and does not have its own light emitting source, a separate device is required to lightly illuminate the entire screen of the LCD element by placing a light source on the rear thereof, wherein the device providing the light is a backlight. Unit (Back Light Unit).

The backlight unit includes a light source unit, a reflective sheet and an optical film.

The light source generates light having a predetermined wavelength.

The reflective sheet reflects the light that is not incident on the optical film among the light generated from the light source to proceed toward the liquid crystal panel.

The optical film includes a diffusion sheet, a prism sheet, and a protective sheet.

The light emitted from the light source and exited toward the liquid crystal panel passes through the diffusion sheet, which diffuses the incident light to prevent the light from being partially concentrated and makes the luminance uniform.

The light passing through the diffusion sheet is sharply lowered in brightness, and a prism sheet is used to prevent this.

1 is a cross-sectional view showing the structure of a conventional prism sheet, Figure 2 is a view showing the distribution of light passing through the prism sheet of FIG.

Referring to FIG. 1, the prism sheet 100 includes a prism support 110 and a plurality of prism shapes 120 formed side by side over the entire surface of the prism support 110.

The prism shape portion 120 forms a substantially isosceles triangle shape when viewed from the front.

A plurality of prismatic features 120 are formed in succession to the prism support 110 to alternately form valleys and mountains. The prism sheet 100 configured as described above refracts the light incident on the prism support part 110 while passing through the prism shape part 120. As a result, light incident at a low angle is concentrated toward the front, thereby increasing luminance in the effective viewing angle range.

However, in the conventional prism sheet 100, some (① or ②) of the light incident on the prism shape part 120 is incident at an effective angle and is collected while passing through the prism shape part 120 to move toward the liquid crystal panel. However, some (③ or ④) could not enter the liquid crystal panel direction because they could not be incident at an effective angle.

That is, as shown in FIG. 2, the amount of light (b area) that is lost to the outside in addition to the light (a area) incident at an effective angle among the light incident on the prism sheet 100 has a problem of decreasing luminance. .

An object of the present invention is to provide an optical film that can improve the brightness by increasing the light condensing efficiency of the incident light by further forming a lens-like structure between the structures, a backlight unit and a method for manufacturing the optical film comprising the same. .

It is also an object of the present invention to provide an optical film having a light condensing and diffusing function, thereby not using a diffusion sheet or a protective sheet, and to provide a backlight unit having a thin thickness.

In order to achieve the above object, the optical film according to an embodiment of the present invention is a surface structured with a plurality of structures; And a smooth surface opposite the structured surface, the structure comprising: a plurality of first structures having a triangular cross section; And a plurality of second structures disposed between the first structures along the longitudinal direction of the first structure and having a lens-shaped cross section.

In addition, the optical film according to another embodiment of the present invention is a surface structured with a plurality of structures; And a smooth surface opposite the structured surface, the structure comprising: a plurality of first structures having a triangular cross section; And a plurality of second structures in which a plurality of lens-shaped protrusions are randomly formed between the first structures.

In one embodiment, a backlight unit includes a light source; And an optical film on which light emitted from the light source is incident, wherein the optical film comprises: a surface structured by a plurality of structures; And a smooth surface opposite the structured surface, the structure comprising: a plurality of first structures having a triangular cross section; And a plurality of second structures disposed between the first structures along the longitudinal direction of the first structure and having a lens-shaped cross section.

According to another embodiment of the present invention, a backlight unit includes a light source; And an optical film on which light emitted from the light source is incident, wherein the optical film comprises: a surface structured by a plurality of structures; And a smooth surface opposite the structured surface, the structure comprising: a plurality of first structures having a triangular cross section; And a plurality of second structures in which a plurality of lens-shaped protrusions are randomly formed between the first structures.

According to an embodiment of the present invention, a method of manufacturing an optical film includes pressing a prism-shaped film with a lens-shaped mold to form a transfer body having grooves corresponding to the lens shape on the prism-shaped peaks; And patterning by applying resin to the transfer member.

The optical film, a backlight unit including the same, and a method of manufacturing the optical film may configure an optical film having a light condensing and diffusing function, thereby not using a diffusion sheet or a protective sheet.

Hereinafter, exemplary embodiments of an optical film including a plurality of structures, a backlight unit including the same, and a method of manufacturing the optical film will be described in detail with reference to the accompanying drawings.

3 is a perspective view illustrating a liquid crystal display device using an edge-light backlight unit according to an exemplary embodiment of the present invention, and FIG. 4 is a cross-sectional view of the liquid crystal display panel of FIG. 3.

3 and 4, a liquid crystal display device (hereinafter, referred to as a “LCD device”) 200 may include a liquid crystal panel 210 displaying an image according to a driving signal and a data signal applied from the outside; The backlight unit 220 is disposed on the rear surface of the liquid crystal panel 210 to illuminate the liquid crystal panel 210.

The liquid crystal panel 210 includes an upper substrate 211b and a lower substrate 211a, a color filter 212, a black matrix 217, a pixel electrode 214, a common electrode 215, a liquid crystal layer 216, and a TFT array. 213, and a pair of polarizing films 218a and 218b are disposed on both surfaces of the liquid crystal panel 210.

The color filter 212 includes a plurality of pixels including red (R), green (G), and blue (B) subpixels, and generates an image corresponding to the color of red, green, or blue when light is applied. .

On the other hand, the pixels are generally composed of red, green, and blue subpixels, but the red, green, blue, and white (W) subpixels constitute one pixel, but are not necessarily limited thereto. Can be.

The TFT array 213 switches the pixel electrode 214 as a switching element.

The common electrode 215 and the pixel electrode 214 convert an array of molecules of the liquid crystal layer 216 according to a predetermined voltage applied from the outside.

The liquid crystal layer 216 is composed of a plurality of liquid crystal molecules, and the liquid crystal molecules change an arrangement in accordance with a voltage difference generated between the pixel electrode 214 and the common electrode 215, whereby the backlight unit ( Light provided from 220 is incident on the color filter 212 in response to a change in the molecular arrangement of the liquid crystal layer 216.

The backlight unit 220 is positioned at the rear of the liquid crystal panel 210 and provides light, for example, white light, to the liquid crystal panel 210.

The backlight unit 220 is a direct light source and a lamp positioned below the liquid crystal panel according to a method of installing a light source, for example, a cold cathode fluorescent lamp (hereinafter referred to as “CCFL”). There is an edge-light method located on the side.

Referring back to FIG. 3, the backlight unit 220 is driven by an edge-light method, and includes a light source unit 222, a light guide plate 224, a reflective sheet 226, and an optical film 228. ).

The light source unit 222 is positioned at the side of the backlight unit 220 and includes a light source 222a and a light source reflector 222b.

As the light source 222a, a cold cathode fluorescent lamp (CCFL) is used. The CCFL is a lamp that provides very bright white light.

In addition to the CCFL, the light source 222a may be a light emitting diode (LED) or an external electrode fluorescent lamp (EEFL).

The LED can be composed of red, green and blue or a single color of white light. In the case of the backlight unit 220 using the LED as a light source, it is possible to maintain the uniformity of the light while miniaturizing the backlight unit 220 and improving the light efficiency.

The EEFL has a higher luminance than the CCFL and is advantageous in that the electrode is external to operate in parallel. In particular, the EEFL can reduce the number of inverters required by the conventional light source, thereby reducing the cost of components and the weight of the LCD module.

The light source reflector 222b mounts the light source 222a and is intended to improve light efficiency by allowing light from the light source 222a to enter the side of the light guide plate 224. To this end, the light source reflector 222b is made of a highly reflective material, and may coat silver (Ag) on its surface.

The reflective sheet 226 is disposed under the light guide plate 224 to reflect light from the light source 222a to the front surface of the light guide plate 224.

The light guide plate 224 is designed such that continuous total reflection occurs below a critical angle after light is incident on the side surface. Since the light source 222a is located at the side of the backlight unit 220, the light generated from the light source 222a is concentrated at the edge of the backlight unit 220 without being uniformly transmitted. Accordingly, the light guide plate 224 is required to uniformly transmit light to the front surface. The light guide plate 224 is generally made of a transparent acrylic resin such as polymethyl methacrylate (hereinafter referred to as "PMMA"). The PMMA is characterized by high strength, low cracking, low deformation, and high visible light transmittance.

In addition, the light guide plate 224 propagates light toward the liquid crystal panel 210.

The optical film 228 may be composed of, for example, a prism sheet.

Light emitted from the light guide plate 224 toward the liquid crystal panel 210 passes through the optical film 228. The optical film 228 condenses or diffuses some of the incident light light toward the liquid crystal panel 210. The remaining light is reflected in the light guide plate 228a. The detailed structure of the optical film 228 is mentioned later.

On the other hand, the optical film 228 of the present invention may not only be composed of one sheet as described above, but may further include a diffusion sheet or a protective sheet (not shown).

Meanwhile, the light may be provided to the liquid crystal panel 210 using the backlight unit of the direct type in addition to the above-described edge-light backlight unit 220.

5 is a cross-sectional view illustrating a backlight unit of a direct type according to another embodiment of the present invention.

Referring to FIG. 5, the backlight unit 320 is driven in a direct light method and includes a light source 322, a diffuser plate 324, a reflective sheet 326, and an optical film 328. do.

The light source 322 is formed by forming a plurality of cold cathode fluorescent lamps (CCFL). The CCFL is a lamp that provides very bright white light.

In addition to the CCFL, the light source 322 may be a light emitting diode (LED) or an external electrode fluorescent lamp (EEFL).

The reflective sheet 326 is positioned below the diffuser plate 324 to reflect light from the light source 322 to the front surface of the diffuser plate 324.

On the other hand, the light source 322 is mounted by placing a light source reflector (not shown) below the light source 322 instead of the reflective sheet 326, and the light emitted from the light source 322 is incident on the diffusion sheet 328a to provide light efficiency. It can also be configured to improve. The light source reflector is made of a highly reflective material, and may be coated with silver (Ag) on the surface.

The diffusion plate 324 passes light incident from the light source 322. The diffusion plate 324 preferably uses polymethyl methacrylate (PMMA).

The optical film 328 may be composed of, for example, a prism sheet.

Light emitted from the diffuser plate 324 toward the liquid crystal panel 210 passes through the optical film 328. The optical film 328 condenses or diffuses part of the incident light toward the liquid crystal panel 210, and the rest The light is reflected toward the diffuser plate 328a. The detailed structure of the optical film 328 is mentioned later.

On the other hand, the optical film 328 of the present invention may not only be composed of one sheet as described above, but may further include a diffusion sheet or a protective sheet (not shown).

Hereinafter, the light emission operation of the LCD element 200 will be described in detail.

Referring back to FIG. 4, the backlight units 220 and 320 provide planar light, which is white light, to the liquid crystal panel 210.

Subsequently, the TFT array 213 switches the pixel electrode 214.

Subsequently, a predetermined voltage difference is applied between the pixel electrode 214 and the common electrode 215, and as a result, the liquid crystal layer 216 is arranged corresponding to the red sub pixel, the green sub pixel, and the blue sub pixel, respectively.

In this case, light provided from the backlight units 220 and 320 passes through the liquid crystal layer 216, and the light amount is adjusted, and the light with the adjusted light amount is provided to the color filter 212.

As a result, the color filter 212 implements an image with a predetermined gray scale.

In detail, a pixel composed of the red subpixel, the green subpixel, and the blue subpixel implements a predetermined image by a combination of light passing through the red subpixel, the green subpixel, and the blue subpixel.

Hereinafter, the structure of the optical films 228 and 328 of this invention is explained in full detail.

6a and 6b are a perspective view and a cross-sectional view schematically showing the structure of an optical film according to an embodiment of the present invention.

6A and 6B, the optical film 400a of the present invention includes a base film 410 and a plurality of structures 420 formed on the front surface of the base film 410.

As such, one surface of the optical film 400a is structured by the plurality of structures 420, and a surface opposite thereto is smoothly formed of the base film 410.

The base film 410 is preferably made of a thermoplastic polymer film that is transparent, flexible, and excellent in processability.

The plurality of structures 420 are disposed side by side over the entire surface of the base film 410. The structure 420 is positioned between the plurality of first structures 422 having a triangular cross section and the first structures 422, and the second structure 424 having a lenticular cross section.

As such, the plurality of first structures 422 and the second structures 424 are alternately formed in succession. The structure 420 configured as described above refracts light incident through the base film 410.

That is, as shown in FIG. 6B, not only the light (① or ②) incident on the first structure 422 is collected at an effective angle, but also the light (③ or ④) incident at a low angle is also the second structure ( Since light is incident on 424, light is concentrated toward the front, so that luminance is increased in the effective viewing angle range.

As such, the optical film 400a of the present invention forms a lens-shaped second structure 424 between the triangular first structures 422 to improve the light condensing efficiency of light incident on the optical film 400a. It is possible to increase the brightness, thereby improving the brightness. Accordingly, since the diffusion sheet or the protection sheet does not need to be provided separately, the thickness of the backlight units 220 and 320 is reduced and manufacturing cost is reduced.

7 to 9 are perspective views schematically showing the structure of an optical film according to another embodiment of the present invention.

First, referring to FIG. 7, the optical film 400b of the present invention includes a base film 410, a plurality of structures 420 and a protective layer 430 formed on the entire surface of the base film 410.

The protective layer 430 is formed on the lower surface of the base film 410 to improve heat resistance of the optical film 400b and to diffuse light incident on the optical film 400b.

In detail, the protective layer 430 is formed by mixing a plurality of beads 434 in a resin 432.

The resin 432 uses acrylic resin having good heat resistance and strong scratch resistance.

The protective layer 430 configured as described above prevents the optical film 400b from being deformed by the heat generated from the light sources 222a and 322. That is, wrinkles do not occur in the optical film 400b due to the resin 432 having high heat resistance, and even when the optical film 400b is deformed at a high temperature, the restoring force of returning the optical film 400b to its original state from normal temperature is good. .

In addition, the protective layer 430 prevents scratches on the optical film 400b due to external impact or other physical force.

Since the structure of the other optical film 400b is the same as the structure of the optical film 400a mentioned above, description is abbreviate | omitted below.

Hereinafter, an optical film according to another embodiment of the present invention will be described in detail.

Referring to FIG. 8, the optical film 500a of the present invention includes a base film 510 and a plurality of structures 520 formed on the front surface of the base film 510.

As described above, one surface of the optical film 500a is structured by the plurality of structures 520, and the surface opposite thereto is smoothly formed of the base film 510.

The base film 510 is preferably made of a thermoplastic polymer film that is transparent, flexible, and excellent in processability.

The plurality of structures 520 are disposed side by side over the entire surface of the base film 510. The structure 520 includes a plurality of first structures 522 having a triangular cross section and a second structure 524 having a plurality of lens-shaped protrusions randomly formed between the first structures 522. do.

As described above, the second structure 524 is randomly positioned between the first structures 522 to refract light incident through the base film 510.

Next, referring to FIG. 9, the optical film 500b according to another embodiment of the present invention includes a base film 510, a plurality of structures 520 and a protective layer 530 formed on the entire surface of the base film 510. ).

The protective layer 530 is formed on the lower surface of the base film 510 to improve heat resistance of the optical film 500b and to diffuse light incident on the optical film 500b.

In detail, the protective layer 530 is formed by mixing a plurality of beads 534 in a resin 532.

Resin 532 uses acrylic resin that is heat resistant and resistant to scratches.

The protective layer 530 configured as described above prevents the optical film 500b from being deformed by the heat generated from the light sources 222a and 322. That is, wrinkles do not occur in the optical film 500b by the resin 532 having high heat resistance, and even when the optical film 500b is deformed at a high temperature, the restoring force of returning the optical film 500b to its original state at a normal temperature is good. .

In addition, the protective layer 530 prevents scratches on the optical film 500b by external impact or other physical force.

Since the structure of the other optical film 500b is the same as that of the optical film 500a of FIG. 8, it abbreviate | omits description below.

10 is a cross-sectional view schematically showing the structure of an optical film according to another embodiment of the present invention.

Referring to FIG. 10, the optical film 600 of the present invention includes a base film 610 and a plurality of structures 620 formed on the front surface of the base film 610.

As such, one surface of the optical film 600 is structured by the plurality of structures 620, and a surface opposite thereto is smoothly formed of the base film 610.

The base film 610 is preferably made of a thermoplastic polymer film that is transparent, flexible, and excellent in processability.

The plurality of structures 620 are disposed side by side over the entire surface of the base film 610.

The structure 620 is characterized by including a plurality of beads 626 therein. As such, since the beads 626 are included in the structure, light incident on the structure 620 is scattered while passing through the beads 626 to increase the light diffusion efficiency and increase haze. . This prevents the light from partially condensing, makes the luminance uniform, and improves the viewing angle.

In addition, the structure 620 includes a plurality of first structures 622 having a triangular cross section and a second structure 624 having a land cross section of the optical film 400 or 500 of the above-described embodiments. Of course, the same as.

Hereinafter, a method of manufacturing an optical film according to embodiments of the present invention will be described in detail.

First, the manufacturing method of the optical film 400 according to an embodiment of the present invention will be described in detail.

11A to 11E are views illustrating a method of manufacturing an optical film according to an exemplary embodiment of the present invention.

Referring to FIG. 11A, first, an upper portion of a prism-shaped film 710 is pressed by a lens-shaped mold 700. As shown in FIG. 11B, the mold 700 has a lens-shaped structure 702 along the longitudinal direction of the mold 700.

Accordingly, as illustrated in FIG. 11C, the transfer body 720 having the groove 722 corresponding to the lens shape along the length direction is formed in the entire prism-shaped peak.

Subsequently, as shown in FIG. 11D, when the resin 730 is applied and patterned on the transfer body 720, an optical film 730 (400) having a shape as shown in FIG. 11E is formed.

The optical film 400 corresponds to the shape of the transfer member 720, and a plurality of structures 420 are formed in the base film 410, and the structures 420 have first structures 422 having a triangular cross section. ) And a first structure 422 forms a second structure 424 having a lens-shaped cross section.

Next, a method of manufacturing the optical film 500 according to another embodiment of the present invention will be described in detail.

12A to 12E are views illustrating a method of manufacturing an optical film according to another embodiment of the present invention.

Referring to FIG. 12A, first, an upper portion of a prism-shaped film 810 is pressed by a lens-shaped mold 800. As shown in FIG. 12B, the mold 800 is characterized in that the plurality of lens-shaped protrusions 802 are randomly formed on the surface of the mold 800.

Accordingly, as illustrated in FIG. 12C, a transfer member 820 is formed on a part of the prism-shaped mountain, in which a protrusion 822 corresponding to the lens shape 802 is randomly formed.

Subsequently, as illustrated in FIG. 12D, when the resin 830 is applied and patterned on the transfer member 820, an optical film 830 (500) having a shape as illustrated in FIG. 12E is formed.

The optical film 500 corresponds to the shape of the transfer member 820, and a plurality of structures 520 are formed in the base film 510, and the structures 520 have first structures 522 having a triangular cross section. ) And a plurality of lens-shaped protrusions randomly form a second structure 524 between the first structures 522.

Preferred embodiments of the present invention described above are merely for purposes of illustration, and those skilled in the art will be able to make various modifications, changes, and additions within the spirit and scope of the present invention. Modifications and additions should be considered to be within the scope of the following claims.

The optical film, the backlight unit including the same, and a method of manufacturing the optical film according to the present invention have an advantage of improving luminance by increasing a light collecting efficiency of incident light by further forming a lens-shaped structure between the structures.

The backlight unit according to the present invention may not use a diffusion sheet or a protective sheet by configuring an optical film having a light condensing and diffusing function, and has a thin thickness.

Claims (19)

A face structured into a plurality of structures; And Including a smooth side opposite the structured side, The structure includes a plurality of first structures having a triangular cross section; And a plurality of second structures disposed along the longitudinal direction of the first structure between the first structures and having a lens-shaped cross section. The method of claim 1, And the structure comprises a plurality of beads. The method of claim 1, Located below the smooth surface, the optical film further comprises a protective layer formed of a resin and a plurality of beads. A face structured into a plurality of structures; And Including a smooth side opposite the structured side, The structure includes a plurality of first structures having a triangular cross section; And a plurality of second structures in which a plurality of lens-shaped protrusions are randomly formed between the first structures. The method of claim 4, wherein And the structure comprises a plurality of beads. The method of claim 4, wherein Located below the smooth surface, the optical film further comprises a protective layer formed of a resin and a plurality of beads. Light source; And It includes an optical film to which the light emitted from the light source is incident, wherein the optical film, A face structured into a plurality of structures; And Including a smooth side opposite the structured side, The structure includes a plurality of first structures having a triangular cross section; And a plurality of second structures disposed between the first structures along a length direction of the first structure and having a lens-shaped cross section. The method of claim 7, wherein And the structure comprises a plurality of beads. The method of claim 7, wherein Located at the bottom of the smooth surface, the backlight unit further comprises a protective layer formed of a resin and a plurality of beads. Light source; And It includes an optical film to which the light emitted from the light source is incident, wherein the optical film, A face structured into a plurality of structures; And Including a smooth side opposite the structured side, The structure includes a plurality of first structures having a triangular cross section; And a plurality of second structures in which a plurality of lens-shaped protrusions are randomly formed between the first structures. The method of claim 10, And the structure comprises a plurality of beads. The method of claim 10, Located at the bottom of the smooth surface, the backlight unit further comprises a protective layer formed of a resin and a plurality of beads. (a) pressing the prism-shaped film with a lens-shaped mold to form a transfer body having grooves corresponding to the lens shape in the prism-shaped peaks; And (b) applying the resin to the transfer member to pattern the method of manufacturing an optical film. The method of claim 13, wherein in step (a), The lens shape is a manufacturing method of an optical film, characterized in that formed along the longitudinal direction of the mold. The method of claim 13, wherein in step (a), The lens shape is a method of manufacturing an optical film, characterized in that a plurality of protrusions are formed randomly on the surface of the mold. The method of claim 14, wherein in step (a), The said transfer body is a manufacturing method of the optical film characterized by the groove | channel corresponding to the said lens shape being formed in the whole longitudinal direction of the said prism shape along the longitudinal direction. The method of claim 15, wherein in step (a), The said transfer body is a manufacturing method of the optical film characterized by the above-mentioned. The method of claim 16, wherein the optical film formed in the step (b), A face structured into a plurality of structures; And Including a smooth side opposite the structured side, The structure includes a plurality of first structures having a triangular cross section; And a plurality of second structures positioned along the length direction of the first structure between the first structures and having a lens-shaped cross section. The method of claim 17, wherein the optical film formed in the step (b), A face structured into a plurality of structures; And Including a smooth side opposite the structured side, The structure includes a plurality of first structures having a triangular cross section; And a plurality of second structures in which a plurality of lens-shaped protrusions are randomly formed between the first structures.

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