KR20070016150A - Optical products for displays - Google Patents

Abstract

The present invention relates to an optical sheet composed of optical films 12a, 12b, 12c laminated on adhesive layers 18a, 18b, 18c. The peripheral edge of the adhesive layer is inserted from the peripheral edge of the optical film. The multilayer optical films are stacked together to form an optical sheet set 10 that is efficiently assembled to an optical display. The optical sheet set 10 adheres dust and particles and exposes no adhesive to the other parts of the display.

Optical sheet for display, adhesive layer, optical film, adhesive, optical sheet set

Description

Optical product for display {OPTICAL PRODUCTS FOR DISPLAYS}

The present invention relates to an optical film. More specifically, the present invention relates to an optical sheet formed by bonding an adhesive to an optical film.

An optical film is one used to increase the amount of light emitted from a display perpendicular to the surface of the optical display or in an "on-axis" direction. Increasing the amount of on-axis light reduces the amount of energy required to produce the desired amount of on-axis light emission. This is particularly important for optical displays using battery powered light sources such as those used in lap-top computers, calculators, digital wrist watches, mobile phones and personal digital assistants.

To solve this problem, 3M brand brightness enhancement film is used. The brightness enhancement film focuses light from the "off-axis" and redirects or "regenerates" the light toward the viewer. In use, this material increases on-axis brightness by sacrificing off-axis brightness.

In addition, there is a " turning " film that is used to increase the amount of on-axis light emitted from the display. Conversion membranes are generally used with wedge light guides. Light rays emitted from the light guide at a grazing angle of less than 30 degrees with respect to the output surface are actually reflected internally to proceed on-axis. Representative examples of conversion membranes are described in US Pat. Nos. 38,243 and 4,984,144.

Another membrane used to increase the on-axis light emitted by the display is a multilayer polymer membrane, such as DBEF from 3M Company. Multilayer polymer membranes are formed from about 700 to 800 polymer layers each layer about 150 nm thick and provide high reflectivity over a wide bandwidth. Representative embodiments are described in US Pat. No. 6,613,421.

In addition to the films described above, other films such as diffuser type films are widely used in optical displays. Multilayer films are arranged between the optical light guide of the liquid crystal display (LCD) and the liquid crystal panel, and it is difficult and inefficient to insert each film individually. This is especially the case for small displays.

In addition, these films are fragile and easily damaged and have a structured surface that must be protected until these films are assembled into a display. In order to prevent scratches or other damage before assembly to the display, a protective cover or pre-mask is laminated to the membrane to protect the structured surface. Placing and removing pre-masks on each film adds to the manufacturing stage of the display, thereby increasing the cost and time required for assembly.

The present invention relates to an optical sheet and a method for producing the optical sheet. The optical sheet includes an optical film laminated on the adhesive layer. The periphery of the adhesive layer is inserted from the periphery of the optical film so that the adhesive is not exposed to stick dust or particles or transfer to other films or components of the optical display.

1 is a front view of a representative embodiment of an optical sheet set for use in a display according to the present invention.

2 is a side cross-sectional view of a representative embodiment of an optical sheet set for use in a display according to the present invention.

3 is a top view of a representative embodiment of an optical sheet.

4 is a top view of another exemplary embodiment of an optical sheet.

5A and 5B are top views illustrating the optical sheet manufacturing method according to the present invention, and FIGS. 5C, 5D and 5E are side cross-sectional views.

5F is a side view illustrating the optical sheet manufacturing method according to the present invention.

1 shows a set of optical sheets according to the invention. 1 is a front view of an optical sheet set 10 for use in a display. As shown, the optical sheet set 10 includes three optical sheets 12a, 12b, 12c and is carried by the liner 14. The optical sheet 12a includes the optical film 16a and the adhesive layer 18a, the optical sheet 12b includes the optical film 16b and the adhesive layer 18b, and the optical sheet 12c includes the optical film 16c. ) And an adhesive layer 18c. The adhesive layer 18a is laminated on the liner 14, and the optical films 16a, 16b, and 16c are laminated in an alternating manner with the adhesive layers 18b and 18c.

In use, the optical sheet set 10 is removed from the liner 14 and assembled between the optical light guide and the liquid crystal panel into an optical display such as an LCD. Laminating the optical films prior to installation into the optical display reduces the time and cost associated with the assembly of the optical display by preventing the operation of inserting each film individually. Installing the optical sheet set 10 into the optical display may be performed using an automated assembly line. The optical sheet set 10 can reduce the amount of debris between the films and reduce damage to the films.

Although the optical sheet set 10 is shown as having three optical films, the number of optical films depends on the display used. Some or all of the optical films may again be of the same shape, depending on the optical display. Examples of the type of optical film that can be used in the present invention include a light directing film, a turning film, a multilayer polymer film, a diffuser film, and the like. In addition, the presence of the adhesive layer 18a is optional.

2 is a cross-sectional side view of an optical sheet set 10 having only two optical films for simplicity. The optical sheet set 10 includes an optical sheet 12a having a film 16a and an adhesive layer 18a and an optical sheet 12b having a film 16b and an adhesive layer 18b. 2 includes distances dτ1 and dτ2, shown as the distance between the edge of the film 16b and the edge of the adhesive layer 18b. The distances dτ1 and dτ2 represent the corresponding distances for any optical sheet. In addition, the displacement length S between the edges of the films 16a and 16b is shown. The displacement length S also represents the corresponding displacement length between pairs of adjacent membranes.

The optical sheets 12a and 12b are separately manufactured initially at the process mentioned later. After fabrication, the optical sheets 12a and 12b are laminated on the optical sheet 12a, which requires the work of aligning the edges of the film 16a with the edges of the film 16b. As shown in Fig. 2, the alignment process is incomplete, and the optical sheet is mainly misaligned by a certain distance. In this figure, misalignment is shown by the displacement length (S). However, the present invention is advantageous even when there is no misalignment between the optical sheets.

If the adhesive layer has been applied across the edge of the optical film, the adhesive may be exposed along the edge due to misalignment that occurs during the lamination of the optical sheet. Exposed adhesive causes two problems. First, dust and particles stick to the exposed adhesive, and second, the exposed adhesive can be easily transferred to other membranes or parts of the display, thereby obstructing vision.

The present invention prevents these problems by recessing the outer edge of the adhesive layer from the edge of the optical film. In Fig. 2, the edge of the adhesive layer 18b is recessed by the distance dτ1, dτ2 from the edge of the optical film 16b. The distances dτ1, dτ2 are preferably between about 0.1 mm and about 1.0 mm, most preferably between about 0.1 mm and about 0.5 mm. However, to be effective, the distances dτ1 and dτ2 must be longer than the displacement length S.

3 is a top view of the optical sheet 12a. The optical sheet 12a includes an optical film 16a having a structured surface 20 and a perimeter 22. The optical film 16a also includes a longitudinal edge 24, a lateral edge 26, a longitudinal edge 28 and a lateral edge 30. The optical sheet 12a further includes an adhesive layer 18a having an outer circumferential edge 32 and an inner circumferential edge 34. The adhesive layer 18a also has a frame side 36 having an outer edge 36o and an inner edge 36i, a frame side 38 having an outer edge 38o and an inner edge 38i, and an outer edge ( 40o) and frame side 40 with inner edge 40i, and frame side 42 with outer edge 42o and inner edge 42i. 3 further shows distances dτ1, dτ2, dℓ1, dℓ2. The distance dτ1 is the distance at which the outer edge 42o is inserted from the lateral edge 30 and the distance dτ2 is the distance at which the outer edge 38o is inserted from the transverse edge 26. The distance d1 is the distance at which the outer edge 40o is inserted from the longitudinal edge 28 and the distance d1 is the distance at which the outer edge 36o is inserted from the longitudinal edge 24.

The adhesive layer 18a has a frame shape so as not to interfere with the viewing area of the optical film 16a. However, the adhesive layer 18a does not have to include all the frame sides 36, 38, 40, and 42. The adhesive layer 18a may include all possible combinations of one or more of the frame sides 36, 38, 40, 42, or portions thereof and may be effective. In fact, there is no special shape condition for the adhesive layer 18a. In addition, an adhesive layer 18a is laminated to the structured surface 20 of the film 16a. Structured surface 20 receives an array of prism elements for propagating light. Prism elements are fragile and generally require protection to add a pre-mask before installing the optical film on the optical display. However, when the optical sheet 12a is laminated to the liner 14 or other optical sheet, the structured surface 20 is protected, thereby avoiding the application of a protective cover or pre-mask to the structured surface 20. Done. This has the added benefit of further saving time and money in the manufacturing process. The adhesive layer 18a may also be applied to the smooth surface of the film 16a opposite the structured surface 20 if desired.

In the above, the limitations and preferred ranges of the distances dτ1 and dτ2 have been described with reference to FIG. This restriction and the preferred range are also applicable to the distances d 1 and d 1. The distances d 1, d 2, d 1, d 1 may or may not be the same for each optical sheet. For example, the distance dτ1 may or may not be the same as the distance dτ2, and the distance dℓ1 may or may not be the same as the distance dℓ2. Therefore, the distances dτ1, dτ2, dℓ1, dℓ2 should be longer than the displacement length S, but all may be different.

The present invention may be described based on the periphery of the optical film 16a and the adhesive layer 18a. Referring again to FIG. 3, the outer periphery 32 of the adhesive layer 18a is inserted from the periphery 22 of the optical film 16a. The inner circumference 34 of the adhesive layer 18a is inserted from the circumferences 22 and 32. Again, the distance between the perimeter 22 and the perimeter 32 can vary but must be longer than the displacement length S.

4 is a top view of another embodiment of an optical sheet 44. The optical sheet 44 includes an optical film 46 and an adhesive layer 48. Fig. 4 also shows the distances dτ1, dτ2, dℓ1, dℓ2 with the same limitations and preferred ranges as described above.

Here, the adhesive layer 48 does not have a frame shape. This embodiment can only be used with an adhesive that does not interfere with the field of view of the optical display.

5a to 5e illustrate a manufacturing method of the present invention. Fig. 5A is a top view showing the adhesive agent 50 bonded to the liner. The adhesive 50 is preferably but not necessarily a plastic adhesive, and may be, for example, a double sided tape laminated on a liner, a liquid adhesive coated on a liner, or one of many forms of bonding the adhesive to the liner.

FIG. 5B is a top view showing the form of the adhesive layer 18 laminated on the liner 14. The adhesive 50 is kiss-cut and the waste material is peeled off. Any of a variety of kiss-cut methods may be performed to form the adhesive layer 48. For example, the cutting operation may be performed continuously or separately to form the outer and inner circumferences. Alternatively, the adhesive layer 18a may be applied directly to the liner 14. 5B also shows that the multilayer adhesive layer 18a can be manufactured at the same time.

5C is a side cross-sectional view taken along line 5c-5c in FIG. 5B. Here, the optical film material 52 is laminated to the adhesive layer 18a to form the intermediate layer 54. Alternatively, the adhesive layer 18a may be applied to the optical film material 52 before being applied to the liner 14.

FIG. 5D is a side sectional view showing the position of the die cut 56 through the optical film material 52. FIG. As shown, die cutting 56 is made by a distance beyond the edge of adhesive layer 18a.

5E is another side cross-sectional view showing the result of cutting the optical film material 52 using die cutting 56 and peeling off the waste material to form the optical film 16a. The optical film 16a is laminated on the adhesive layer 18a to form the optical sheet 12a. These are again laminated to the liner 14. Alternatively, the adhesive layer 18a may be directly applied to the optical film 16a.

The optical sheets 12a are sequentially laminated to each other or to another optical sheet such as the optical sheets 12b and 12c to form the optical sheet set 10. 5F is a side view showing the shape of the optical sheet set 10 formed by laminating three optical sheets. The optical sheet 12a forms a bottom layer and remains in contact with the liner 14. The optical sheet 12b is removed from the liner 14 and laminated on top of the optical sheet 12a. Thereafter, the optical sheet 12c is removed from the liner 14 and laminated on top of the optical sheet 12b.

As mentioned above, an important advantage of the present invention is that it prevents exposure of the deadly adhesive to the display. The following examples illustrate the effectiveness of the present invention.

Yes

A set of optical sheets formed of three optical sheets was produced by the method of the present invention. The bottom and middle optical sheets comprise the Thin-BEF of the 3M Company and the top optical sheets comprise the DBEF of the 3M Company. Double-sided tape such as Sumitomo 3M # 4040 or # 4037 formed an adhesive layer. Each membrane has a size of 40 mm x 50 mm. The adhesive layer has a frame shape in which a strip of 1 mm extends around the membrane. The outer periphery of each adhesive layer was recessed by a distance of about 0.5 mm from the periphery of the membrane.

The optical sheet set was exposed to room conditions (23 ° C., 50% relative humidity). After seven days, the appearance of the edges was checked. There was no dust or particle build up on the edges.

Next, an optical sheet set was placed between the glass plates and placed on top of 500 g. Samples were stored at 65 ° C. and 50% relative humidity. After three days, the glass plate was checked. No adhesive was delivered to the glass plate.

Comparative example

The second optical sheet set was produced in the same manner as in the above example except that the adhesive layer was not recessed from the edge of the film. Instead, the outer periphery of the adhesive layer was aligned with the periphery of the membrane.

The optical sheet set in this example was exposed to the same conditions as described in the above example. However, here dust and particles were attached to the adhesive exposed on the edge, the adhesive was transferred to the glass plate and the optical sheet was attached to the glass plate.

In addition to the advantages illustrated by these examples, the present invention provides a method of efficiently assembling a multilayer optical film in an optical display. No pre-mask is needed anymore, and the multilayer film can be installed at the same time. This advantageously reduces the time and costs associated with manufacturing optical displays for the manufacturer.

Although the present invention has been described above with reference to preferred embodiments, those skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.

Claims (49)

Cutting the adhesive material to form an adhesive layer having a first length and a first width, Bonding the surface of the optical film material to the adhesive layer to form an intermediate material, Essentially cutting only the optical film material of the intermediate material to form an optical sheet comprising the optical film and the adhesive layer, wherein the optical film of the optical sheet has a second length longer than the first length and a second width wider than the first width. Having optical product manufacturing method. The method of claim 1, Stripping the closed adhesive material surrounding the adhesive layer; Stripping the waste optical film material surrounding the optical film. The optical product manufacturing method according to claim 1, wherein a plurality of optical sheets are manufactured at the same time. The method of claim 1, further comprising laminating an adhesive material on the liner. The method of claim 1, wherein the adhesive layer has a frame shape. The method of claim 1, wherein the adhesive layer has a portion of a frame shape. The method of claim 1 wherein the surface of the optical film material is a structured surface. The method of claim 1, Manufacturing a plurality of optical sheets, Laminating a plurality of optical sheets to form a set of optical sheets. The method of claim 8, wherein a plurality of types of optical films are formed on the optical sheet set. Cutting the adhesive material to form an adhesive layer having a frame shape having a first periphery, Laminating an optical film material on an adhesive layer; Cutting the optical film material to form an optical sheet comprising an adhesive layer and an optical film having a second peripheral edge, wherein the first peripheral edge of the adhesive layer is inserted from the second peripheral edge of the optical membrane. The method of claim 10 wherein the adhesive material is a double sided tape. The method of claim 10 wherein the optical film material has a structured surface. The method of claim 10, wherein the insertion distance is about 0.1 mm to about 1.0 mm. The method of claim 10, wherein the insertion distance is about 0.1 mm to about 0.5 mm. The method of claim 10 further comprising laminating an adhesive material on the liner. The method of claim 10, Manufacturing a plurality of optical sheets, Laminating a plurality of optical sheets to form a set of optical sheets. The method of claim 16, wherein the optical film is selected from a plurality of different types of optical films. Applying an adhesive layer to the liner, Bonding the surface of the optical film material to the adhesive layer, Essentially cutting only the optical film material to form an optical sheet comprising an optical film and an adhesive layer having at least one edge, The adhesive layer is inserted from at least one edge of the optical film. 19. The method of claim 18, further comprising stripping off the waste optical film material surrounding the optical film. The method of claim 18, Manufacturing a plurality of optical sheets, Laminating a plurality of optical sheets to form a set of optical sheets. 21. The method of claim 20, wherein the insertion distance is longer than the misaligned displacement length between adjacent optical sheets. The method of claim 20, wherein the insertion distance is at least 0.1 mm. Applying an adhesive layer to the optical film having at least one edge, The adhesive layer is inserted from at least one edge of the optical film. The method of claim 23, wherein the insertion distance is at least 0.1 mm. An adhesive layer having an edge, a first length and a first width, An optical film in contact with the adhesive layer and having an edge and a second length longer than the first length and a second width wider than the first width, The edge of the adhesive layer is recessed from the edge of the optical film. The optical sheet of claim 25, wherein the adhesive layer has a frame shape. The optical sheet of claim 25, wherein the adhesive layer has a portion of a frame shape. 27. The optical sheet of claim 25, wherein the distance between the first and second lengths and the distance between the first and second widths is from about 0.1 mm to about 1.0 mm. The optical sheet of claim 25, wherein the distance between the first length and the second length and the distance between the first width and the second width are from about 0.1 mm to about 0.5 mm. The optical sheet according to claim 25, wherein the optical film is selected from the group consisting of a light guide film, a switching film, a diffuser film, and a multilayer optical film. 27. The optical sheet of claim 25, wherein the adhesive layer is a double sided tape. An optical film having an outer periphery, An optical sheet comprising an adhesive layer laminated under the optical film and having an outer periphery inserted from the outer periphery of the optical film. 33. The optical sheet of claim 32, wherein the optical film is a structured surface. 34. The optical sheet of claim 33, wherein the adhesive layer is in contact with the structured surface of the optical film. 33. The optical sheet of claim 32, further comprising a liner laminated below the adhesive layer. A plurality of optical films having an outer periphery, A plurality of adhesive layers having an outer periphery inserted from the outer periphery of the optical film and an inner periphery inserted from the outer periphery of the adhesive layer, An optical sheet in which an optical film and an adhesive layer are laminated | stacked alternately. 37. The optical sheet of claim 36, wherein the optical film has a structured surface. 38. The optical sheet of claim 37, wherein each optical film is selected from the group consisting of a light guide film, a switching film, a diffuser film, and a multilayer optical film. 38. The optical sheet of claim 37, wherein one adhesive layer is in contact with the structured surface of one optical film. 37. The optical sheet of claim 36, further comprising a liner laminated under the plurality of optical films and the adhesive layer. And a plurality of laminated optical sheets, each optical sheet having an adhesive layer and an optical film having at least one edge completely covering the adhesive layer, wherein the adhesive layer is recessed from at least one edge of the optical film. 42. The optical sheet set according to claim 41, wherein each optical film is selected from the group consisting of a light guide film, a switching film, a diffuser film, and a multilayer optical film. 42. The optical sheet set of claim 41, wherein the recess distance is about 0.1 mm to about 1.0 mm. 42. The optical sheet set of claim 41, wherein the recess distance is about 0.1 mm to about 0.5 mm. 42. The optical sheet set according to claim 41, wherein the recess distance is a distance longer than the misaligned displacement length between adjacent optical sheets. A set of optical sheets formed by a plurality of optical sheets comprising an adhesive layer and an optical film laminated so that the outer edge of each adhesive layer is recessed from the outer edge of the adjacent optical film. 47. The optical sheet set according to claim 46, wherein the adhesive layer has a frame shape. 47. The optical sheet set of claim 46, wherein the adhesive layer has a portion of a frame shape. 47. The optical sheet set according to claim 46, wherein the outer edge of each adhesive layer is recessed by a distance longer than the misaligned displacement length between adjacent optical sheets from the outer edge of each adjacent optical film.

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