KR20160013627A - Soft mold for optical film and method of fabricating the same - Google Patents

Abstract

A soft mold for manufacturing an optical sheet and a method of manufacturing the same are provided. A method of manufacturing a soft mold for optical sheet production comprises the steps of preparing a soft mold for manufacturing a sheet-like optical sheet having a mold pattern layer formed on one side of a mold base material, arranging the mold base material so as to face both ends of the mold base material with the mold pattern layer facing outward A step of asking a bonding tape to the other side of the mold base material at the interviewed site, and a step of fusing both ends of the mold base material by irradiating a laser beam to the interviewed region at the top of the interviewed site.

Description

Technical Field [0001] The present invention relates to a soft mold for manufacturing an optical sheet and a manufacturing method thereof,

The present invention relates to a soft mold for manufacturing an optical sheet and a method of manufacturing the same.

A liquid crystal display (LCD) is a device for displaying an image by injecting liquid crystal between two glass plates and applying power to the upper and lower glass plate electrodes to change the arrangement of liquid crystal molecules in each pixel. Unlike a cathode ray tube (CRT), a plasma display panel (PDP) or the like, a display using a liquid crystal display device is not usable in a place where there is no light because the display itself is non-luminous. In order to compensate for these drawbacks, a backlight assembly that is uniformly irradiated on the information display surface is mounted for the purpose of enabling use in a dark place.

BACKGROUND ART [0002] As a low-power, high-brightness liquid crystal display device is required, a backlight assembly has optical sheets of various optical patterns such as a prism sheet.

Such an optical sheet is usually formed by a transfer method using a mold. Conventionally, a hard mold has been widely used as a mold for manufacturing an optical sheet. The hard mold forms an engraved pattern on the surface of the cylindrical drum and transfers it to the film.

However, hard molds are not only costly, but also difficult to implement the engraved pattern in the width direction. Recently, a method of using a soft mold of a closed curve loop shape has attracted much attention.

The soft mold performs a continuous process by forming a closed curve loop. Both ends of the soft mold should be connected to form a closed curve loop, and an adhesive tape is usually used for the connection.

However, since the adhesive tape has insufficient tensile strength, there is a possibility that the joint is broken during the manufacturing process. In addition, it is possible that a seam step occurs in the optical sheet roll produced as the adhesive tape has a predetermined thickness, and thus the optical sheet is partially deflected. Further, defects that are demonstrated in a stain-like shape may be generated by pressing due to the step of the seam

SUMMARY OF THE INVENTION It is an object of the present invention to provide a soft mold for manufacturing an optical sheet capable of improving a stepped joint of an optical sheet produced with high strength.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method of manufacturing a soft mold for manufacturing an optical sheet capable of improving a stepped joint of an optical sheet produced with high strength.

The problems of the present invention are not limited to the above-mentioned problems, and other problems not mentioned can be clearly understood by those skilled in the art from the following description.

According to an aspect of the present invention, there is provided a soft mold for manufacturing an optical sheet, comprising: a mold base material including a mold base material having one end and the other end fused to each other to form a joint, and a mold pattern layer formed on one side of the mold base material, .

According to another aspect of the present invention, there is provided a method of manufacturing a soft mold for manufacturing an optical sheet, the method comprising: preparing a soft mold for manufacturing a plate-shaped optical sheet having a mold pattern layer formed on one side of the mold substrate; Placing a bonding tape on the other side of the mold base material at the contacted area, and attaching a bonding tape to the other side of the mold base substrate from the upper side of one side of the contacted area, And fusing both ends of the mold base material.

The details of other embodiments are included in the detailed description and drawings.

The embodiments of the present invention have at least the following effects.

That is, according to the soft mold for manufacturing an optical sheet according to the embodiments of the present invention, the strength of the joint portion can be improved, defective deflection of the sheet and defective stain due to seam step can be improved.

The effects according to the present invention are not limited by the contents exemplified above, and more various effects are included in the specification.

1 is a perspective view of a soft mold for manufacturing an optical sheet according to an embodiment of the present invention.
2 is a cross-sectional view taken along line II-II 'of FIG.
3 is a cross-sectional view taken along line III-III 'of FIG.
4 is a plane photograph of a joint portion of a soft mold for producing an optical sheet.
5 is a cross-sectional view for explaining a method of joining both ends of a soft mold for manufacturing an optical sheet of Fig.
6 is a schematic view of an optical sheet manufacturing apparatus employing the above-described soft mold for manufacturing an optical sheet.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention, and the manner of achieving them, will be apparent from and elucidated with reference to the embodiments described hereinafter in conjunction with the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Is provided to fully convey the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims.

It is to be understood that elements or layers are referred to as being "on " other elements or layers, including both intervening layers or other elements directly on or in between. On the other hand, a device being referred to as "directly on" refers to not intervening another device or layer in the middle. Like reference numerals refer to like elements throughout the specification. "And / or" include each and any combination of one or more of the mentioned items.

Although the first, second, etc. are used to describe various components, it goes without saying that these components are not limited by these terms. These terms are used only to distinguish one component from another. Therefore, it goes without saying that the first component mentioned below may be the second component within the technical scope of the present invention.

The terminology used herein is for the purpose of illustrating embodiments and is not intended to be limiting of the present invention. In the present specification, the singular form includes plural forms unless otherwise specified in the specification. The terms " comprises "and / or" comprising "used in the specification do not exclude the presence or addition of one or more other elements in addition to the stated element.

Unless defined otherwise, all terms (including technical and scientific terms) used herein may be used in a sense commonly understood by one of ordinary skill in the art to which this invention belongs. Also, commonly used predefined terms are not ideally or excessively interpreted unless explicitly defined otherwise.

The terms spatially relative, "below", "beneath", "lower", "above", "upper" And can be used to easily describe a correlation between an element and other elements. Spatially relative terms should be understood in terms of the directions shown in the drawings, including the different directions of components at the time of use or operation. For example, when inverting an element shown in the figures, an element described as "below" or "beneath" of another element may be placed "above" another element . Thus, the exemplary term "below" can include both downward and upward directions. The components can also be oriented in different directions, so that spatially relative terms can be interpreted according to orientation.

As used herein, the term "sheet" can be used in the sense of " film "

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

1 is a perspective view of a soft mold for manufacturing an optical sheet according to an embodiment of the present invention. 2 is a cross-sectional view taken along line II-II 'of FIG.

1 and 2, a soft mold 100 for manufacturing an optical sheet includes a mold base 110 and a mold pattern layer 120 formed on one side of the mold base 110. [

The mold substrate 110 may be made of a material having a bending property. For example, the mold substrate 110 may be made of polyethylene terephthalate (PET) having a thickness of 125 to 300 mu m. The mold pattern layer 120 may be made of a thermosetting resin such as an acrylic resin, a urethane resin, a polyester resin or the like, an ultraviolet curing resin such as an epoxy acrylate resin, a urethane acrylate resin, a silicone acrylate resin or the like. The pattern shape of the mold pattern layer 120 is in a complementary relation to the pattern of the optical sheet to be produced. The pattern of the optical sheet is formed by transferring the pattern of the mold pattern layer 120.

When the soft mold 100 for producing an optical sheet is intended to form a prism pattern, the mold pattern layer 120 of the soft mold 100 for manufacturing an optical sheet includes an engraved pattern of a prism pattern. The extending direction of the prism pattern may be the longitudinal direction of the mold base material 110, but may be the width direction.

Both ends of the mold base material 110 are bonded by mutual fusion so that the soft mold 100 for producing an optical sheet forms a closed curve as a whole.

3 is a cross-sectional view taken along line III-III 'of FIG. 4 is a plane photograph of a joint portion of a soft mold for producing an optical sheet.

Referring to FIGS. 3 and 4, both ends of the mold base 110 in the soft mold 100 for optical sheet manufacturing are joined together by fusing to form a joint 150. The welding process width (width of the joint 150) may be about 1 to 2 mm. A bonding tape 130 is attached to the other side of the mold base 110 at the joint 150. The other side surface of the mold substrate 110 is opposite to the side where the mold pattern layer 120 is formed. The bonding tape 130 may comprise a laser absorbing material. The bonding tape 130 may be omitted.

The mold pattern layer 120 may be formed on the entire surface of one side of the mold substrate 110 but may be omitted or removed from the fused portion and may be formed of the same material as the mold pattern layer 120, (125) may be disposed at least partially. The mold pattern residual layer 125 may remain after the mold pattern layer 120 is melted and re-cured. The height of the mold pattern residual layer 125 becomes smaller than the height of the mold pattern layer 120.

5 is a cross-sectional view for explaining a method of joining both ends of the soft mold 100 for manufacturing an optical sheet of FIG.

First, a soft mold 100 for manufacturing a sheet-shaped optical sheet is prepared. Usually, the raw material of the soft mold 100 for optical sheet production is continuously formed with the mold pattern layer 120, and can be stored in the form of a roll. The soft mold 100 for manufacturing an optical sheet can be cut to an appropriate length to prepare a soft mold 100 for producing a sheet-shaped optical sheet.

Thereafter, one end and the other end of the soft mold 100 for optical sheet production are arranged so as to face the mold pattern layer 120 in the closed curve loop in a state where the mold pattern layer 120 faces outward, and a bonding tape 130 to attach one end of the mold base 110 to the other end. The bonding tape 130 uses a material containing a laser absorbing material. Then, suction or the like is placed on the other side of the mold base 110, and the mold base 110 is fixed by applying a negative pressure.

Next, a pressing member 90 made of a transparent material such as polymethyl methacrylate (PMMA) is pressed on one side of the mold base 110. Next, laser welding is performed. Specifically, a laser is irradiated from the upper portion of the pressing portion 90 to cause the laser to pass through the pressing portion 90 and the mold pattern layer 120 of the soft mold 100 for optical sheet production and the mold base 110, 130). As the bonding tape 130 absorbs the laser, heat is generated, and both ends of the mold base material 110 are mutually fused by the heat. In this process, the mold pattern layer 120 immediately above the fused portion may be melted and partially re-cured to remain the mold pattern residual layer 125. The bonding tape 130 may be removed during or after the process.

Examples of usable laser welding include an Alexandrite laser (wavelength: about 770 nm), a diode laser (wavelength: 800 nm to 1000 nm), and an Nd: YAG laser (Nd: YAG laser; However, in the Alexandrite laser system, the mold base material 110 may not be sufficiently fused due to its short wavelength. In the ND: YAG laser system, energy is concentrated in a cone shape in the center portion, Lt; / RTI > On the other hand, since the diode laser system has a cap-shaped energy distribution, it can be preferably applied to the fusion of the mold base material 110.

6 is a schematic view of an optical sheet manufacturing apparatus employing the above-described soft mold for manufacturing an optical sheet.

6, the optical sheet manufacturing apparatus includes a winding roll 10, a winding roll 20, a drum roll 30, a plurality of guide rolls 80, a first resin supply portion 40, a second resin supply portion 50, a first resin curing portion 61, and a second resin curing portion 62. Further, it may further include a soft mold 100 for manufacturing an optical sheet provided so as to extend over the drum roll 30 and the guide roll 80.

The unwinding roll 10 supplies the target film 70 (substrate). The winding roll 20 winds the patterned film 72 (optical sheet) into a roll shape. The guide roll 80 guides movement or rotation of the films 71 and 72 and the soft mold 100 for optical sheet production.

The soft mold 100 for manufacturing an optical sheet surrounds the outer side of the drum roll 30 and spreads on the guide roll 80 or the like. The drum roll 80 is made of a rubber material, and the soft mold 100 for manufacturing an optical sheet rotates along a closed curve loop as the drum roll 80 rotates. The mold base material 110 of the soft mold 100 for optical sheet production is directed to the inside of the closed curve loop and the mold pattern layer 120 is directed to the outside. Although the pattern of the mold pattern layer 120 is formed in the width direction of the closed curve loop for illustrative purposes, it is also possible to form the pattern in the longitudinal direction.

The first resin supply unit 40 includes a transfer roll 41 and a first full dam 42. The first full dam 42 is supplied with resin. The transfer roll 41 is disposed on the upper side of the first liquid dam 42 and the resin of the first liquid dam 42 is buried on the surface and then the soft mold 100 for manufacturing an optical sheet for moving the resin, Lt; / RTI > The resin may fill the recessed portion of the mold pattern layer 120 of the soft mold 100 for optical sheet production. A plurality of pairs of the transfer rolls 41 and the first full dam 42 may be disposed to more completely fill the engraved portions.

The second resin supply portion 50 is disposed in the vicinity of the drum roll 30. The second resin supply part 50 may include a nozzle 51 and a second liquid dam 52. The nozzle 51 ejects the resin to the second liquid dam 52. The second full dam (52) has a width equal to or similar to the width of the object film (71). The second liquid dam 52 has a jetting port on the lower surface thereof, and can uniformly supply the resin supplied from the nozzle 51 to the soft mold 100 for optical sheet production passing through the lower portion. The resin of a predetermined thickness is uniformly supplied to the soft mold 100 for optical sheet production in which the resin is supplied into the engraved pattern by the first resin supply portion 40,

Thereafter, the soft mold 100 for producing an optical sheet and the target film 71 are brought into contact with each other on the drum roll 30. A guide roll 80 is disposed at a portion where the soft mold 100 for optical sheet production and the target film 71 are in contact with each other to define a gap between the guide roll 80 and the drum roll 30, The mold 100 and the target film 71 are pressed. Thereafter, the soft mold 100 for producing an optical sheet and the object film 71, which are in contact with each other, pass through the first resin curing portion 61. The first resin curing portion 61 is disposed in the vicinity of the drum roll 30 to provide UV or heat to primary cure the resin. The curing here can be a hardening.

After the primary curing, the soft mold 100 for producing an optical sheet and the film 72 are separated. In this process, the resin on the soft mold 100 for optical sheet production is all transferred to the film 72 side, and the soft mold 100 for optical sheet production moves again along the closed loop to the first resin supply portion 40 side.

On the other hand, the film 72 on which the optical pattern is transferred moves to the second resin curing portion 62 and is secondarily cured by receiving UV or heat. Here, the curing may be the main curing. When both the first resin curing portion 61 and the second resin curing portion 62 use UV, the second resin curing portion 62 can use a relatively high-pressure UV. The secondary cured optical sheet 72 is wound by the winding roll 20.

The soft mold 100 for optical sheet production transfers the resin to the film 71 while rotating the closed curve loop repeatedly. If the soft mold 100 for optical sheet production has reached the end of its life, it should be replaced. When the soft mold 100 for manufacturing an optical sheet is to be installed, the soft mold 100 for manufacturing an optical sheet before fusion bonding may be first installed in a closed curve loop, and then both ends may be fusion-bonded . In the latter case, a laser processing machine 91 is installed in the optical sheet manufacturing apparatus. The laser processing machine 91 includes a pressing portion as described above. The mounting position may be between the first resin supply portion 40 and the second resin supply portion 50. In this case, however, the laser processing machine 91 need not be fixed but can be installed in a movable manner.

In the case of this embodiment, the joint 150 of the soft mold 100 for optical sheet production is connected by fusion. This approach provides greater durability than tape-connected soft mold 100 seams 150 for conventional optical sheets. Experimental results showed that the tensile strength was only 5.2 kg when bonded using a tape, but it was confirmed that the tensile strength when fused using a laser was 33.9 kg and the strength was about 6 times or more. As described above, when the durability of the soft mold 100 for manufacturing an optical sheet is increased, the replacement cycle is lengthened and the process efficiency can be improved.

On the other hand, the optical sheet to be manufactured is transferred not only the portion where the mold pattern of the soft mold 100 for optical sheet production is formed but also the portion of the joint 150. Since the portion where the joint 150 is transferred is difficult to apply as an optical pattern, it is cut and removed when a practical product is applied. The cycle of the transfer of the transfer portion of the seam 150 of the optical sheet coincides with the closed loop loop length of the soft mold 100 for optical sheet production.

Since the optical sheet is usually stored in a roll state, the diameter of the optical sheet becomes larger as the roll is wrapped around the roll. The portion where the joint 150 is overlapped with the next optical sheet is a portion where a normal optical pattern is formed. When the joint 150 of the soft mold 100 for manufacturing an optical sheet is connected by a tape, since the thickness of the tape is thick, the portion of the optical sheet 150 to which the joint 150 is transferred has no resin layer, It becomes very thin. If the stepped portion of the joint 150 is subjected to pressure in the roll, defects may occur in which the optical sheet is partially bent as the next overlapping optical sheet enters the joint 150 side. When such an optical sheet is applied to a display, the stain can be visually recognized.

On the other hand, in the case where the joint 150 of the soft mold 100 for optical sheet production is fused with the laser as in the embodiment of the present invention, since the thickness of the resin layer has a proper thickness in the transfer portion of the joint 150, Defects can be prevented.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, You will understand. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive.

100: Soft mold
110: mold substrate
120: mold pattern layer
125: mold pattern residual layer
130:
150: Joints

Claims (12)

1. A mold base material comprising: a mold base material having one end and the other end mutually fused to form a joint; And
And a mold pattern layer formed on one side of the mold base material. The method according to claim 1,
And a bonding tape attached to the other side of the mold base material at the joint portion. 3. The method of claim 2,
Wherein the bonding tape comprises a laser absorbing material. The method of claim 3,
Wherein the laser absorbing material is a laser absorbing material in a wavelength range of 800 nm to 1000 nm. The method according to claim 1,
And the mold pattern layer is removed from the joint portion. 6. The method of claim 5,
And a mold pattern residual layer formed on one side of the mold base material at the joint portion and made of the same material as the mold pattern layer. The method according to claim 1,
And the width of the seam is 1 to 2 mm. Preparing a soft mold for manufacturing a plate-shaped optical sheet having a mold pattern layer formed on one side of the mold base material;
Arranging both ends of the mold base material so as to face each other with the mold pattern layer facing outward;
Attaching a bonding tape to the other side of the mold base material at the interviewed site; And
And irradiating a laser beam from the upper side of the one side of the interposed region to the interposed region to fuse both ends of the mold base material. 9. The method of claim 8,
Wherein the laser is a diode laser. 10. The method of claim 9,
Wherein the diode laser has a wavelength band of 800 nm to 1000 nm. 9. The method of claim 8,
Wherein the bonding tape comprises a laser absorbing material. 9. The method of claim 8,
Before the step of irradiating the laser,
Placing a negative pressure device on the other side of the mold base material at the interviewed site and fixing the mold base material by applying a negative pressure; And
Further comprising the step of pressing on one side of the mold base material using a pressing portion.

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