KR20120109132A - Backlight unit and method for manufacturing the same - Google Patents

Abstract

PURPOSE: A backlight unit and a manufacturing method thereof are provided to automatically form reflection films on the other sides of a light guide plate except for a light incident surface of the light guide plate, thereby increasing production. CONSTITUTION: Ink is transferred on a printing pad(s15). The printing pad moves to a printing location where the printing pad faces one side of a fixed light guide plate to make one side of the printing pad faces upward(s17). The ink of the printing pad is transferred onto one side of the light guide plate(s19). A reflection film is formed. The printing pad moves to an initial position(s21). [Reference numerals] (S11) Fixing light guide plate; (S13) Filling engraved part of image plate with ink; (S15) Ink is transferred on a printing pad; (S17) Printing pad ascends and moves to a printing location; (S19) Printing pad descends and applies ink to the lateral side of the light guide plate; (S21) Printing pad moves to an initial position

Description

BACKLIGHT UNIT AND METHOD FOR MANUFACTURING THE SAME}

The present invention relates to a backlight unit and a manufacturing method thereof, and more particularly, to a backlight unit capable of minimizing light loss of a backlight unit by reflecting a side surface of the light guide plate.

A liquid crystal display device (LCD), which is advantageous for moving picture display and has a large contrast ratio and is actively used in TVs and monitors, exhibits optical anisotropy and polarization properties of a liquid crystal, And the like.

Such a liquid crystal display is an essential component of a liquid crystal panel bonded through a liquid crystal layer between two side-by-side substrates, and realizes a difference in transmittance by changing an arrangement direction of liquid crystal molecules with an electric field in the liquid crystal panel. do.

However, since the liquid crystal panel does not have its own light emitting element, a separate light source is required in order to display the difference in transmittance as an image. To this end, a backlight unit in which a light source is embedded is disposed on the back of the liquid crystal panel.

The backlight unit includes a light source and is classified into a direct type and an edge type according to the position of the light source. The backlight unit of the direct type emits light from the light source by arranging the light source under the liquid crystal panel. It is a method of directly supplying the light to the liquid crystal panel, the backlight unit of the side-type method is disposed from the light source by using the refraction and reflection in the light guide plate by arranging the light guide plate under the liquid crystal panel, and by placing the light source on at least one side of the light guide plate Indirect light is supplied to the liquid crystal panel.

In this case, the side type backlight unit is easier to manufacture than the direct type backlight unit, and has a thin shape, light weight, and low power consumption.

1 is an exploded perspective view of a backlight unit of a conventional side view type.

As shown in FIG. 1, the conventional side type backlight unit 20 includes a light source, a light guide plate 23 disposed on the same plane as the light source, and having at least one side surface facing the light source, and a lower portion of the light guide plate 23. The reflective plate 25 is positioned and a plurality of optical sheets 21 mounted on the light guide plate 23.

As a light source, fluorescent lamps such as Cold Cathode Fluorescent Lamps (CCFLs) and External Electrode Fluorescent Lamps (EEFLs) have been widely used. Light Emitting Diodes (LEDs, hereinafter called LEDs) 29a, which have advantages in terms of weight, brightness, and the like, are replacing fluorescent lamps.

The light guide plate 23 is positioned so that light emitted from each of the plurality of LEDs 29a faces the light incident surface of the light guide plate 23.

The light guide plate 23 allows the light incident from each of the plurality of LEDs 29a to totally reflect, and evenly spreads to a wide area of the light guide plate 23 while traveling inside the light guide plate 23 so that the surface light source can be emitted.

On the other hand, the lower portion of the light guide plate 23 is provided with a reflecting plate 25 for reflecting the light exiting to the lower surface of the light guide plate 23, the upper portion of the light guide plate 23 a plurality of optical sheets for realizing high brightness ( 21).

Accordingly, the light emitted from each of the plurality of LEDs 29a is incident on the light incident surface of the light guide plate 23 and then emitted in the form of a more uniform surface light source.

Here, a reflective tape 70 capable of reflecting light is attached to the light incident surface of the light guide plate 23 facing the plurality of LEDs 29a serving as the light source, at least one side thereof.

The reflective tape 70 prevents light incident by the light incident surface of the light guide plate 23 from being refracted from leaking to the outside through the side surface of the light guide plate 23 to minimize light loss of the backlight unit.

This, the reflective tape 70 is attached by the operator's manual work, as it depends on the handling of the operator in this way causes a poor handleability due to handling, resulting in a high defective rate resulting in a low product completion rate, The reattachment work has a problem in that workability and productivity are significantly reduced.

Accordingly, the present invention, the reflective film that can reflect the light in an automated manner except the light incident surface of the light guide plate is formed to increase the workability and productivity, and minimize the defective rate and its manufacturing method The purpose is to provide.

In order to achieve the above object, a method of manufacturing a backlight unit according to the present invention includes a first step of transferring ink to a printing pad; A second step of moving the printing pad, to which the ink is transferred, to a printing position facing the one side of the light guide plate fixed with one side facing upward; A third step of forming a reflective film by transferring the ink of the printing pad to one side of the light guide plate; And a fourth step of moving the print pad to an initial position.

One side of the light guide plate may be one of the remaining side surfaces except for at least one light incident surface of the light guide plate.

And repeating the first step to the fourth step to retransmit the ink to the one side of the light guide plate.

The second step may include moving the printing pad, on which the ink is transferred, to a printing position facing a portion of the one side of the light guide plate fixed to one side thereof.

And repeating the first to fourth steps, transferring the ink of the printing pad to the remaining part of the one side of the light guide plate to form the reflective film.

Repeating the first to fourth steps to transfer the ink to at least one light incident surface of the light guide plate and one or more remaining sides except for the one side of the light guide plate and forming the reflective film. It is characterized by.

And rotating the light guide plate 90 degrees clockwise or counterclockwise.

It is characterized in that it further comprises the step of filling ink in the intaglio portion of the image plate.

Drying the ink transferred to one side of the light guide plate is characterized in that it further comprises.

The thickness of the ink transferred to one side of the light guide plate is characterized in that it is formed in the range of 20㎛ to 35㎛,

The thickness of the ink transferred to one side of the light guide plate is characterized in that the intaglio depth of the negative plate of the image plate to adjust.

The ink is characterized in that the pigment ink.

The ink is characterized in that corresponding to one of white and silver.

Meanwhile, according to the present invention, a backlight unit including a reflector, a light guide plate formed on the reflective plate, a plurality of optical sheets formed on the light guide plate, and a light source positioned on at least one side of the light guide plate may include: It includes a reflective film formed by transferring the ink of the printing pad on at least the other side of the light guide plate except for one side.

According to the backlight unit and a manufacturing method thereof according to the present invention, it is possible to increase the workability and productivity by allowing the side reflection treatment process of the light guide plate, which was dependent on the manual operation of the operator, to be processed in an automated manner.

In particular, it is not necessary to reattach the reflective tape due to the poor handling of the operator according to the automated process, so that the production cost can be reduced, the handling failure rate can be eliminated, and the processing time can be shortened.

In addition, it is possible to reduce the labor cost according to the automated process, which helps to reduce the production and processing costs of the liquid crystal display.

In addition, it is possible to double the effects described above by applying the present invention to the light guide plate including the projection, which is difficult to attach the reflective tape.

1 is an exploded perspective view of a conventional side-by-side backlight unit.
2 is an exploded perspective view schematically illustrating a liquid crystal display module according to an exemplary embodiment of the present invention.
3 is a view illustrating the light guide plate of FIG. 2;
4 schematically shows a pad printer according to an embodiment of the present invention.
5A to 5D are diagrams showing a pad printing process of the pad printer according to the embodiment of the present invention.
6 is a flow chart showing a pad printing process according to an embodiment of the invention.
FIG. 7A illustrates a luminance measurement point measured by the luminance meter in the backlight unit. FIG.
FIG. 7B is a table illustrating results of experiments of a conventional backlight unit and a backlight unit to which the present invention is applied through the luminance meter of FIG. 7A. FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 2 is an exploded perspective view schematically illustrating a liquid crystal display module according to an exemplary embodiment of the present invention, and FIG. 3 is a view illustrating the light guide plate of FIG. 2.

As shown in FIG. 2, the liquid crystal display device module 100 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 the cover bottom 150, the top cover 140.

The liquid crystal panel 110 plays a key role in image expression. The liquid crystal panel 110 includes first and second substrates 112 and 114 bonded to each other with a liquid crystal layer interposed therebetween.

Although not shown in the drawings, a plurality of gate lines and data lines intersect on the inner surface of the first substrate 112, which is commonly referred to as a lower substrate or an array substrate, under the premise of an active matrix scheme, and pixels are defined at each intersection. A thin film transistor (TFT) is provided to correspond one-to-one with a transparent pixel electrode formed in each pixel.

In addition, the inner surface of the second substrate 114 called the upper substrate or the color substrate may correspond to each pixel, for example, a color filter of red (R), green (G), and blue (B) color and each of them. A black matrix covering the non-display elements such as gate lines, data lines, and thin film transistors is provided. In addition, a transparent common electrode covering them is provided.

In addition, polarizing plates (not shown) for selectively transmitting only specific light are attached to the outer surfaces of the first and second substrates 112 and 114, respectively.

In addition, the printed circuit board 117 is connected through at least one edge of the liquid crystal panel 110 through a connection member 116 such as a flexible circuit board or a tape carrier package (TCP). In the support main 130 side or cover cover 150 may be properly folded to be in close contact with the back.

Accordingly, the liquid crystal panel 110 having the above-described structure may be configured to have a data driving circuit when the thin film transistor selected for each gate line is turned on by an on or off signal of a gate driver circuit transmitted through the printed circuit board 117. The signal voltage is transmitted to the corresponding pixel electrode through the data line, and 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 so that the difference in transmittance can be displayed as an image.

The backlight unit 120 includes a light source arranged along an edge of the support main 130, a reflector 125, a light guide plate 123 seated on the reflector 125, and a plurality of optical sheets interposed thereon. (121).

As a light source, an LED 129a is used. Each of the plurality of LEDs 129a is spaced at a predetermined interval and mounted on a printed circuit board (PCB) 129b to form an LED assembly 129.

Although not shown in the drawings, a fluorescent lamp may be used instead of the LED assembly 129, and when the fluorescent lamp is used, a lamp guide for protecting and guiding the outside of the fluorescent lamp and concentrating light toward the light guide plate 123 is further provided. May be included.

The LED assembly 129 is fixed by a method such as adhesion so that light emitted from the plurality of LEDs 129a faces the light incident surface of the light guide plate 123.

Although the LED assembly 129 is illustrated to be arranged only on one side of the light guide plate 123 in the drawing, it may be arranged on one or more sides of the light guide plate 123, for example, but is not limited thereto. Can be.

Light emitted from the plurality of LEDs 129a of the LED assembly 129 is indirectly supplied to the liquid crystal panel 110 by using the refraction and reflection of the light guide plate 123.

Then, an LED driver integrated circuit (IC) (not shown) for driving each block of the LED assembly 129 is mounted.

The reflection plate 125 is positioned on the rear surface of the light guide plate 123 to reflect the light passing through the rear surface of the light guide plate 123 toward the liquid crystal panel 110 to improve the brightness of the light.

The light guide plate 123 evenly spreads the light incident from each of the plurality of LEDs 129a to a wide area of the light guide plate 123 while propagating through the light guide plate 123 by a plurality of total reflections to provide a surface light source to the liquid crystal panel 110. Be sure to

The light guide plate 123 may include a pattern of a specific pattern on the back surface to supply a uniform surface light source. The pattern may be configured in various ways, such as an elliptical pattern, a polygon pattern, a hologram pattern, and the like to guide the light incident to the light guide plate 123. The lower surface of the 123 may be formed by a printing method or an injection method.

Meanwhile, a reflective film 170 capable of reflecting light is formed on the light incident surface of the light guide plate 123, that is, the side surface of the light guide plate 129 except for the side where the LED assembly 129 is positioned. It is formed by applying ink through. The reflective film 170 is formed by applying ink to all of the remaining side surfaces of the light guide plate 123 except for the light incident surface, but is shown by hatching in the drawings for convenience of description.

The reflective film 170 serves to minimize light loss of the backlight unit 120 by preventing light from leaking to the outside through the side of the light guide plate 123. Particularly, in the case of the side type, the light incident surface of the light guide plate 123 is used. The incident light reflects the light so that it is not emitted through the other side except the light incident surface of the light guide plate 123, it plays a more important role.

Referring to FIG. 3, the second to fourth side surfaces 123-2 and 123-except for the first side surface 123-1 where the LED assembly 129 is positioned to become a light incident surface of the light guide plate 123. 3 and 123-4 are formed with a reflective film 170 capable of reflecting light so that light incident through the first side 123-1 is not emitted, and light is guided through the reflective film 170. The second to fourth sides 123-2, 123-3, and 123-4 of 123 are prevented from exiting to the outside.

Although not shown in the drawings, at least one side surface of the light guide plate 123 except for the light incident surface may include a protrusion, and the protrusion may help to stably couple the light guide plate 123 to the support main 130. Play a role.

As such, when the protrusion is included in the light guide plate 123, the reflective film 170 is similarly formed on the side of the protrusion to prevent light from being emitted through the side of the protrusion.

Meanwhile, the reflective film 170 formed on the second to fourth side surfaces 123-2, 123-3, and 123-4 except for the first side surface 123-1, which is the light incident surface of the light guide plate 123, may use pad printing. The printing pad of the pad printing press fills ink on the intaglio of the engraved image plate, and transfers the ink to the printing pad through the intaglio, thereby printing the transferred ink on the second to fourth side surfaces of the light guide plate. 2, 123-3 and 123-4, the reflective film 170 is formed. A detailed description thereof will be given later.

The thickness of the reflective film 170 is preferably in the range of 20 μm to 35 μm, but the thickness may be changed in various ways if the total light characteristic indicating the average luminance and the uniformity of luminance satisfies a predetermined standard.

The all-optical characteristic represents the average luminance and the uniformity of the luminance. The average luminance and the luminance uniformity (the highest luminance at the measured n points) are obtained by using the luminance values measured at each of a plurality of preset points on the front of the backlight unit 120. A ratio calculated by dividing the value by the lowest luminance value and multiplying by 100), where the average luminance value indicating the brightness of the light is high and the luminance indicating the luminance deviation at each of the plurality of points in front of the backlight unit 120. The lower the uniformity, the better the total light characteristics.

Accordingly, good all-optical characteristic means that the screen of the backlight unit 120 is bright and light is evenly emitted from the screen.

The all-optical characteristic may be determined by the reflective film 170. The reflective film 170 may satisfy the preset all-optical properties by adjusting the type of ink (including ink color) and the thickness of the ink. Here, the thickness of the ink can be adjusted to the intaglio depth of the image plate of the pad printer.

The plurality of optical sheets 121 mounted on the light guide plate 123 include a diffusion sheet, one or more prism sheets, a protective sheet, and the like, and diffuse or condense the light passing through the light guide plate 123 to form the liquid crystal panel 110. The more uniform surface light source is incident.

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

More specifically, the liquid crystal panel 110 and the backlight unit 120 are covered with a top cover 140 that covers the top edge of the liquid crystal panel 110 in a state where the liquid crystal panel 110 and the backlight unit 120 are surrounded by a support main body 130 having a rectangular- The cover bottoms 150 covering the back surface of the main body 120 are coupled to each other at the front and rear sides,

As it is modularized, light emitted from each of the plurality of LEDs 129a of the backlight unit 120 is incident on the first side surface 123-1, which is the light incident surface of the light guide plate 123, and then the liquid crystal panel therein. It is refracted toward 110 and processed into a more uniform surface light source of high quality while being passed through the plurality of optical sheets 121 together with the light reflected by the reflector 125 to be supplied to the liquid crystal panel 110. .

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

Meanwhile, although the side type (Edge Type) method of arranging the LED assembly 129 on one side of the light guide plate 123 has been described in the drawing, more LEDs 129a than the side type method have a lower portion of the liquid crystal panel 110. It is also possible to apply a direct type method of supplying light directly to the liquid crystal panel 110 by disposing in the.

This is an exceptional case when the light guide plate is included in the direct type backlight unit, and the light guide plate included in the direct type backlight unit includes a reflective film that can reflect light on all four sides thereof, It is desirable to prevent light from being emitted to the outside.

4 is a view schematically showing a pad printing machine according to an embodiment of the present invention.

Here, the light guide plate is the same as the light guide plate of FIGS. 2 and 3, and the first side surface 123-1 and the third side surface 123-3 of the light guide plate correspond to the long edge, and the second side surface 123-2 of the light guide plate The fourth side 123-4 corresponds to a short edge, and the LED assembly (129 of FIG. 2) is positioned on the first side 123-1 of the light guide plate when the backlight unit is assembled.

As shown in FIG. 4, the pad printer 200 includes an image plate 202, an ink spraying unit 206, and a printing pad 208, which are not shown in the drawing to support and fix the light guide plate 123. The light guide plate fixing part may further include a rotating means for rotating the light guide plate.

The image plate 202 includes an intaglio 204 for filling ink, wherein the intaglio 204 is formed at least once on the second to fourth sides 123-2, 123-3, and 123-4 of the light guide plate. It can be formed to a size that can apply the ink.

The depth of the intaglio portion 204 may be determined according to the thickness of the ink applied to the second to fourth side surfaces 123-2, 123-3, and 123-4 of the light guide plate.

The ink injection part 206 includes a first moving means (not shown) capable of moving the ink injection part 206 from side to side, and through the first moving means to the intaglio portion 204 of the image plate 202. It moves and ejects ink to fill the engraved portion 204 with ink, and returns to the initial position.

The printing pad 208 is made of silicon which can prevent static electricity, and the second to fourth sides 123-2 and 123-3 of the light guide plate are transferred to the ink transferred through the intaglio 204 of the image plate 202. 123-4) to form a reflective film (170 in FIG. 2).

The printing pad 208 includes a second moving means (not shown) for moving the printing pad 208 up, down, left, and right, and thus the injection position or the light guide plate 123 in which the intaglio portion of the image plate 202 is located. Move to the printing position.

The light guide plate fixing part (not shown) serves to fix and support the light guide plate 123.

The rotating means (not shown) rotates the light guide plate 123 by 90 degrees in a clockwise or counterclockwise direction so as to reflect the reflective film (2) on the second, third or fourth side surfaces 123-2, 123-3, and 123-4 of the light guide plate. 170 of FIG. 2 may be formed. For example, the third light guide plate 123 may be rotated 90 degrees counterclockwise so that the second side surface 123-2 faces upward. The side 123-3 may face upward.

5A to 5D are diagrams illustrating a pad printing process of a pad printer according to an embodiment of the present invention, and FIG. 6 is a flowchart illustrating a pad printing process according to an embodiment of the present invention. Referring to FIG. The pad printing process will be described from the second aspect.

First, when the second side surface 123-2 of the light guide plate to be printed is fixed to the upper side (s11), the pad printer 200 loads the fixed light guide plate 123 to the printing position. Here, the light guide plate 123 may be directly fixed to the printing position without loading.

In addition, the pad printer 200 moves the ink injection unit 206 to the injection position to fill the intaglio 204 of the image plate 202 (s13), and as shown in FIG. 5A, the image plate 202. The printing pad 208 located on the upper part of the bottom) is lowered from the initial position to transfer the ink to the printing pad 208 (S15).

The ink is preferably white or silver with good reflection characteristics, but is not limited thereto and other colors may be applied.

On the other hand, ink can be largely classified into pigment type and dye type. Of these, the pigment type contains a coagulant or a fixing agent, and when applied to a predetermined surface, the ink particles cause chemical reactions and are deposited on the surface. It is preferable to use among these pigment types because the total light property is higher than the dye type. Such inks may comprise one or more of pigments, such as coagulants or fixing agents, resins and solvents.

Thereafter, as shown in FIGS. 5B and 5C, the pad printer 200 raises the printing pad 208 to which the ink is transferred and moves it to the printing position where the light guide plate 123 is located (S17).

Finally, as illustrated in FIG. 5D, the printing pad 208 is lowered to apply ink to the second side surface 123-2 of the light guide plate to form a reflective film (170 of FIG. 2) (S19).

In addition, the pad printer 200 may apply the ink through the above-described pad printing process to form a reflective film (170 of FIG. 2), and then raise and move the printing pad 208 again to return to the initial position (s21). ).

In this case, the pad printing process as described above may be performed by dividing the long side into one or more at the short side and the long side corresponding to the second side surface 123-2 of the light guide plate.

In addition, the above-described pad printing process may be repeated at least once to adjust the thickness of the reflective film (170 of FIG. 2) applied to the second side surface 123-2 of the light guide plate, and change the ink color to another color. You can also reapply.

The thickness of the reflective film 170 is preferably in the range of 20 to 35 μm, but the thickness may be changed in various ways if the total light characteristic indicating the average luminance and the uniformity of luminance satisfies a predetermined standard.

After the pad printing process is completed with respect to the second side surface 123-2 of the light guide plate as described above, the third side surface 123-3 of the light guide plate is rotated by 90 degrees counterclockwise. The pad printing process is repeated, and the pad printing process is repeated. Similarly, the fourth side surface 123-4 of the light guide plate is repeated in the same manner.

On the other hand, although not shown in the drawings, it is preferable to form the reflective film by applying ink to the second to fourth side surfaces of the light guide plate and drying the applied ink.

In detail, the ink may be applied to the second, third or fourth side of the light guide plate and dried through the dryer, or the ink may be applied to all of the second to fourth sides of the light guide plate. The applied ink can be dried through a dryer. The dryer may be a NIR (Near Infra-Red) dryer.

As described above, the pad printer on the second to fourth sides 123-2, 123-3, and 123-4 except for the first side 123-1 corresponding to the light incident surface of the light guide plate 123. Since the reflective film can be automatically formed, the reflection processing process can be simplified, productivity can be improved, and the handling defects caused by the operator can be eliminated. In addition, by reducing labor costs and minimizing defect rate by automation, it is possible to reduce the production and processing costs of the liquid crystal display module, and to shorten the process time. In particular, in the case of the light guide plate 123 including the protrusion, which is more difficult to attach the reflective tape, the effect is greater.

FIG. 7A is a view illustrating luminance measurement points measured by a luminance meter in a backlight unit, and FIG. 7B is a table illustrating results of experiments of a conventional backlight unit and a backlight unit to which the present invention is applied through the luminance meter of FIG. 7A.

Referring to FIG. 7A, 17 luminance measurement points designated on a front surface of a backlight unit are shown. The backlight unit includes a reflecting plate, a light guide plate, and a plurality of optical sheets sequentially mounted on the first side of the light guide plate included in the backlight unit. The LED assembly is positioned to face the light incident surface of the light guide plate, and ink is applied to the remaining second to fourth surfaces through a pad printing process according to the present invention to form a reflective film.

A luminance meter (not shown) divides the front surface of the backlight unit to specify 17 luminance measurement points and measures luminance values at each of the 17 luminance measurement points, which are emitted vertically from each of the 17 luminance measurement points. Detect light and measure luminance value.

The average luminance value is calculated using the measured luminance values, the highest luminance value among the luminance values measured at each of the 17 luminance measurement points is divided by the lowest luminance value, and the luminance uniformity is calculated by multiplying by 100.

7B shows an average luminance value and luminance uniformity of each of the first backlight unit and the second to seventh backlight units to which the present invention is applied.

At this time, in Table 1, the first backlight unit (corresponding to 'conventional' in Table 1) includes a light guide plate with a reflective tape, and the second backlight unit (corresponding to 'W2' in Table 1) uses white ink as the second ink. A light guide plate that has been repeatedly coated, and the third backlight unit (corresponding to 'W3' in Table 1) includes a light guide plate that has been repeatedly coated with white ink, and the fourth backlight unit ('W4' in Table 1). Corresponding) includes a light guide plate repeatedly coated with white ink a fourth time, and the fifth backlight unit (corresponding to 'S2' in Table 1) includes a light guide plate repeatedly coated with silver ink a second time, and a sixth backlight unit. (Corresponding to 'S3' in Table 1) includes a light guide plate having a third repeated coating of silver ink, and the seventh backlight unit (corresponding to 'S4' in Table 1) has a light guide plate having repeatedly applied silver ink four times. It includes.

In this case, the average luminance represents the average value of the luminance values measured at the first luminance measurement point 1P and the luminance values measured at the five luminance measurement points, and the luminance value at the first luminance measurement point is min. 6340 cd / m² or above, Typ 7200 cd / m² or above, average luminance value at 5 luminance measuring points must be at least 5840 cd / m² and above 6630 cd / m² The criteria are met.

In the table, the luminance uniformity is calculated by dividing the highest luminance value among the luminance values from the first luminance measurement point to the ninth luminance measurement point by the lowest luminance value and multiplying by 100 (hereinafter, referred to as 9P uniformity). And the highest luminance value among the luminance values from the first luminance measurement point to the seventeenth luminance measurement point divided by the lowest luminance value and then multiplied by 100 to express a value (hereinafter, referred to as 17P uniformity). Typ should be less than 1.15, Max should be less than 1.25, and 17P uniformity should be less than 1.4 (Typ) and less than 1.5 (Max).

Referring to the table, the average luminance value (7249cd / m, 6665cd / m) of the fourth backlight unit W4 satisfies the preset criteria (standard 7200cd / m, 6630cd / m² or more), and the conventional first backlight unit (conventional) It can be seen that the average luminance value (7432cd / m, 6849 cd / m) of almost close to, the uniformity of the luminance (1.14) of the sixth and seventh backlight unit (S3, S4) satisfies the preset criteria (1.15 or less) It can be seen that the brightness uniformity (1.13) of the conventional first backlight unit (conventional) is similar.

Accordingly, by forming a reflective film by adjusting the color and type of the ink and the coating thickness of the ink, a backlight unit having an all-optical characteristic equivalent to or superior to that of a conventional reflective tape (reflective tape attached to the light guide plate of the first backlight unit) is obtained. I can produce it.

As described above, according to the backlight unit and the manufacturing method thereof according to the present invention, the reflective tape, which has been conventionally attached by hand, can be applied to pad printing in an automated manner to facilitate the reflection processing of the light guide plate even if the light guide plate becomes slim. Will be.

The present invention is not limited to the above embodiments, and various modifications can be made without departing from the spirit of the present invention.

110: liquid crystal panel 120: backlight unit
121: multiple optical sheets 123: light guide plate
125: reflector 129: LED assembly
130: support main 140: top cover
150: cover bottom

Claims (14)

A first step of transferring ink to a printing pad;
A second step of moving the printing pad, to which the ink is transferred, to a printing position facing the one side of the light guide plate fixed with one side facing upward;
A third step of forming a reflective film by transferring the ink of the printing pad to one side of the light guide plate;
Fourth step of moving the printing pad to the initial position
Method of manufacturing a backlight unit comprising a.
The method of claim 1,
One side of the light guide plate
Method of manufacturing a backlight unit, characterized in that one of the remaining side except for at least one light incident surface of the light guide plate.
The method of claim 1,
By repeating the first step to the fourth step
And retransmitting the ink to the one side of the light guide plate.
The method of claim 1,
The second step comprises:
And moving the printing pad, to which the ink is transferred, to a printing position facing a portion of the one side of the light guide plate fixed with one side facing upward.
The method of claim 4, wherein
Repeating the first to fourth steps to transfer the ink of the printing pad to the remaining part of the one side of the light guide plate to form the reflective film. .
The method of claim 1,
By repeating the first step to the fourth step
And transferring the ink to at least one light incident surface of the light guide plate and at least one remaining side surface except for the one side of the light guide plate, and forming the reflective film.
The method of claim 1,
And rotating the light guide plate 90 degrees in the clockwise or counterclockwise direction.
The method of claim 1,
The method of manufacturing a backlight unit, characterized in that it further comprises the step of filling ink in the negative portion of the image plate.
The method of claim 1,
And drying the ink transferred to one side of the light guide plate.
The method of claim 1,
The thickness of the ink transferred to one side of the light guide plate is
Method for producing a backlight unit, characterized in that formed in the range of 20㎛ to 35㎛.
The method of claim 10,
The thickness of the ink transferred to one side of the light guide plate is
The manufacturing method of the backlight unit, characterized in that for adjusting the intaglio depth of the negative plate of the image plate.
The method of claim 1.
The ink is
Method for producing a backlight unit, characterized in that the pigment ink.
13. The method of claim 12,
The ink is
Method for manufacturing a backlight unit, characterized in that corresponding to one of white and silver.
A backlight unit comprising a reflector, a light guide plate formed on an upper portion of the reflector, a plurality of optical sheets formed on the light guide plate, and a light source positioned on at least one side of the light guide plate.
And a reflective film formed by transferring the ink of the printing pad to at least one side of the light guide plate except for one side.

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