JP2009217165A - Method for manufacturing pattern sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily manufacture an optical sheet which has a viewing angle controlling layer where prism rows and light shielding parts having an air layer inside are alternately arranged. <P>SOLUTION: The optical sheet 1, having the viewing angle controlling layer 2 where the prism rows 11 and the light shielding parts 40 are alternately arranged, is obtained by charging ink 41 from a groove forming surface side of a base material sheet 10 where the prism rows 11 and grooves 20 are alternately arranged. The light shielding part 40 includes an opening end side of the groove made of an ink hardened material 41' and a bottom 23 side of the groove made of the air layer 42. The base material sheet 10 is formed so that the width of the opening end 22 of the groove is broader than that of the bottom 23 of the groove in an arrangement direction of a cross section of the groove 20, and a flank of the groove has a bent 26 composed of a first surface 24 of the opening end side and a second surface 25 of the bottom side in the cross section. When θ1 and θ2 respectively denote angles made by each of the first surface 24 and the second surface 25 with a thickness direction D of the base material sheet 10, a relation: θ1>θ2 is satisfied. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an optical sheet used as a luminance distribution control sheet, a light diffusion sheet, a diffusivity control sheet, a peep prevention sheet, a contrast improvement sheet, and the like in a planar light source element, a display, a screen and the like.

  As an optical sheet used as a light diffusion sheet or the like in a CRT display, a liquid crystal display device, a plasma display device, a rear projection display device, etc., a prism array having a trapezoidal section and a light shielding portion having a substantially V-shaped section are alternately arranged. An optical sheet having a viewing angle control layer, wherein an ink made of a low refractive index resin is used as a light shielding material for the viewing angle control layer, and the structure of the light shielding part is left in the groove having a substantially V-shaped cross section. It is known that only the opening of the groove is filled with ink, or the entire groove is filled with ink, and the total reflection at the interface between the prism row and the light shielding portion is used (Patent Document 1).

  The manufacturing method of this viewing angle control layer is as follows. First, a UV-curing resin is filled between a transparent sheet and a molding die, and a cross section is trapezoidal by a transfer molding method (2P molding method (Photo Polymerization process)). A base sheet in which the prism rows and grooves having a substantially V-shaped cross section are alternately arranged is manufactured. Next, ink is supplied between the base sheet and the translucent sheet. The ink is filled in the groove of the base sheet by passing through the pressing roll.

  As a similar method for manufacturing the viewing angle control layer, first, a base sheet having a large number of V-shaped grooves arranged in parallel is manufactured, and then ink is applied to the parallel surfaces of the grooves to apply ink in the grooves. A method of filling and then scraping off excess ink on a substrate sheet with a doctor or the like (scraping printing method) is known (Patent Document 2).

  In addition, as an optical sheet having a viewing angle control layer in which prism rows and light-shielding portions are alternately arranged, a reflection layer is provided on one side of the prism row to form an optical sheet for a reflective screen (Patent Document 3). .

JP 2000-352608 A JP 2006-178092 A JP 2006-301588 A

  In the viewing angle control layer using total reflection described above, it is preferable that an air layer is present in the light shielding portion in order to increase the light use efficiency. However, in the conventional optical sheet, it is difficult to fill the opening of the groove only with the light shielding material so as to leave an air layer inside the groove, and in particular, it is extremely difficult to make the filling amount of the light shielding material constant. It is.

  In contrast, according to the present invention, in an optical sheet having a viewing angle control layer in which prism rows and light shielding portions are alternately arranged, a light shielding portion having an air layer therein can be easily manufactured. With the goal.

  The present inventor uses the base sheet used for manufacturing the viewing angle control layer as a base sheet having a specific bent portion in the groove, and fills ink only in a wide groove width on the opening end side of the groove, It has been found that an air layer can stably exist in a narrow groove portion on the bottom side of the groove.

That is, the present invention is an optical sheet having a viewing angle control layer in which prism rows and light shielding portions are alternately arranged,
In the cross section of the light shielding portion in the arrangement direction, the light shielding portion is formed such that the end on one side of the optical sheet is wider than the end on the other side (hereinafter, the wider end is the wider end and the narrower end is smaller). Is called the narrow end),
In the cross-section, the side surface of the light-shielding portion has a bent portion including a first surface on the wide end side and a second surface on the narrow end side, and an angle between the first surface and the thickness direction of the optical sheet is θ1, second Θ1> θ2 where θ2 is an angle between the surface and the thickness direction of the optical sheet,
The light-shielding portion provides an optical sheet characterized in that the wide end side is made of a cured ink and the narrow end side is an air layer.

Further, according to the present invention, as the optical sheet manufacturing method described above, the prism rows and the light shielding portions are alternately arranged by filling the ink from the groove forming surface side of the base sheet in which the prism rows and the grooves are alternately arranged. The light-shielding part has a viewing angle control layer, and the light shielding part is a method for producing an optical sheet in which the opening end side of the groove is made of an ink cured product, and the bottom side of the groove is made of an air layer,
As a base sheet, in the cross section in the groove arrangement direction, the width of the opening end of the groove is formed wider than the width of the bottom of the groove,
In the cross section, the side surface of the groove has a bent portion including a first surface on the opening end portion side and a second surface on the bottom portion side, and an angle between the first surface and the thickness direction of the base sheet is θ1, second Provided is a manufacturing method characterized by using a material satisfying θ1> θ2 where θ2 is an angle formed by the surface and the thickness direction of the base sheet.

  According to the optical sheet of the present invention, since the wide end side of the light shielding portion of the viewing angle control layer is made of an ink cured product and the narrow end side of the light shielding portion is an air layer, total reflection at the interface between the prism row and the light shielding portion. When the light diffusivity is controlled by using the light, the light use efficiency can be improved. In addition, regarding the decrease in the light shielding performance due to the fact that the ink is not filled to the bottom of the groove, the amount of ink that is filled near the bottom of the groove is smaller than the amount of ink that is filled near the end of the opening. Small and practically not a problem.

  Further, according to the optical sheet manufacturing method of the present invention, since the base sheet having a specific bent portion on the side surface of the groove is used as the base sheet used for manufacturing the viewing angle control layer, on the bottom side of the groove Makes it easy to fill the ink only on the opening end side of the groove while leaving the air layer, and therefore, the wide end side of the light shielding portion is made of a cured ink and the narrow end side of the light shielding portion is an air layer. It is possible to easily manufacture the optical sheet of the present invention.

  Hereinafter, the present invention will be described in detail with reference to the drawings. In addition, in each figure, the same code | symbol represents the same or equivalent component.

  FIG. 1 is a perspective view of an optical sheet 1 according to an embodiment of the present invention used as a backlight brightness enhancement sheet, a viewing angle control sheet, a diffusivity control sheet, a contrast improvement sheet, and the like. It is a perspective view of the base material sheet 10 used for manufacture of the optical sheet 1. FIG.

  This base sheet 10 has a substantially trapezoidal prism array 11 on one side and a plurality of grooves 20 having a substantially V-shaped cross section arranged alternately in a stripe pattern. The optical sheet 1 is a base sheet 10. The ink cured product 41 ′ is filled only on the opening end 22 side of the groove 20, and the air layer 42 exists on the bottom 23 side of the groove 20. In this optical sheet 1, the viewing angle control layer 2 is configured by alternately arranging the light-shielding portions 40 made of the ink cured product 41 ′, the air layer 42, and the prism rows 11.

  FIG. 3 is a cross-sectional view in the arrangement direction of the grooves 20 of the base sheet 10. As shown in the figure, the groove 20 of the base sheet 10 is formed such that the width of the open end 22 is wider than the width of the bottom 23. Further, a bent portion 26 is formed on each of the opposing side surfaces 21 of the groove 20, which includes a first surface 24 on the opening end 22 side and a second surface 25 on the bottom 23 side.

  The first surface 24 and the second surface 25 have an angle θ1 formed by the first surface 24 and the thickness direction D of the base sheet 10, and an angle formed by the second surface 25 and the thickness direction D of the base sheet 10. When θ2 is satisfied, θ1> θ2 is satisfied. Therefore, as shown in the figure, the groove 20 has a large groove width in the depth direction of the groove 20 from the bent portion 26 to the opening end 22 side, and the groove width from the bent portion 26 to the bottom 23 side is the groove width. Suddenly narrows. Therefore, as illustrated in FIG. 4A, the ink 41 is applied to the base sheet 10 from the surface on which the grooves 20 are formed, and the ink 41 is filled into the grooves 20. By performing a scraping printing method in which excess ink 41 is scraped off by a doctor or the like, the air layer 42 remains on the bottom 23 side from the bent portion 26 and the groove 20 is bent as shown in FIG. It becomes easy to fill the ink 41 only from the portion 26 to the opening end 22 side. Therefore, by curing the ink 41, as shown in FIG. 3C, the light shielding portion 40, in which the wide end 43 side of the bent portion 26 is made of the ink cured product 41 ′ and the narrow end 44 side is made of the air layer 42, is formed. The optical sheet 1 having it can be easily obtained.

  In the present invention, as shown in FIG. 5, the cross-sectional shape of the groove 20 may be rounded without the bent portion 26 being rounded. In this case, the first surface 24 and the second surface 25 sandwiching the bent portion 26 are extrapolated, and the angle formed by the extrapolation line of the first surface 24 and the thickness direction D of the base sheet 10 is θ1 and the second surface 25. Θ1> θ2 is satisfied, where θ2 is an angle formed by the extrapolation line of the sheet and the thickness direction D of the base sheet 10.

  As shown in FIG. 6, the cross-sectional shape of the groove 20 may be such that the side surface 21 is bent between the bent portion 26 of the groove 20 and the opening end portion 22, or may be curved as shown in FIG. 7. . In this case, when the angle formed by the side surface 27 of the opening end 22 with the thickness direction D of the base sheet 10 is θ3, it is preferable that θ3 <θ1. In addition, although it is preferable to form the bending part 26 in both the side surfaces 21 which oppose in the groove | channel 20, you may form in one side surface.

  Here, a preferable range of the angle θ1 is 45 to 90 °. If θ1 is smaller than 45 °, the ink 41 easily enters the bent portion 26 to the bottom 23 side, so that it is difficult to form the air layer 42 in the groove 20. On the other hand, even if θ1 is larger than 90 °, the effect of forming the air layer 42 in the groove 20 is not particularly great, and there is a problem in the manufacture and moldability of the mold for forming the base sheet 10. There is.

  Moreover, the preferable range of angle (theta) 2 is 3-30 degrees. If θ2 is smaller than 3 °, the effect of controlling the viewing angle in the optical sheet 1 may be reduced, and there may be a problem in the manufacture and moldability of a mold for forming the base sheet 10. On the other hand, if θ2 is larger than 30 °, the ink 41 is easily filled up to the bottom 23 of the groove 20, and it becomes difficult to form the air layer 42 in the groove 20.

  Further, when the side surface 21 is bent between the bent portion 26 of the groove 20 and the opening end portion 22 as shown in FIG. 6 or is bent as shown in FIG. Is preferably substantially parallel to the sheet surface of the substrate sheet 10, and in particular, θ1 is preferably approximately 90 °, and the shape shown in FIG. 8 is preferable.

  Further, with reference to FIG. 8, a specific groove width and the like are shown. The groove width W1 at the bent portion 26 is 1 to 200 μm, and the groove width W2 of the open end 22 is larger than W1 to 10 to 500 μm. It is preferable. If the groove width W1 in the bent portion 26 is smaller than 1 μm, there may be a problem in the manufacturing and moldability of the mold of the base sheet 10, and conversely if larger than 200 μm, the air layer 42 is formed in the groove. Becomes difficult. If W2 is smaller than 10 μm, it is difficult to make a difference in the ease of filling the ink 41 into the groove between the bent portion 26 and the opening end 22 side and the bent portion 26 to the bottom 23 side. In contrast, it becomes difficult to form the air layer 42 therein, and even if W2 is larger than 500 μm, the effect of forming the air layer in the groove is not particularly increased.

  The bottom 23 of the groove may be formed at an acute angle, but the chamfering width W3 may be chamfered to about 0.5 to 5 μm or may be formed into a curved surface.

  The pitch W4 of the grooves 20 is preferably 50 to 500 μm from the viewpoint of high definition required for the optical sheet 1 and durability and moldability of the molding die for the base sheet 10.

  Regarding the depth L1 of the groove 20, the ratio L1 / W2 between the depth L1 of the groove 20 and the width W2 of the opening end 22 of the groove 20 is 2 to 2 from the viewpoint of the viewing angle required for the optical sheet 1 and the formability. It is preferably about 10 and particularly preferably 20 to 500 μm.

  The distance L2 between the opening end 22 of the groove and the bent portion 26 is preferably 5 to 100 [mu] m from the viewpoint of providing a thickness that can sufficiently shield light.

  The thickness L3 of the base sheet 10 may be thicker than the depth L1 of the groove 20, but is preferably 1.5 or more of the depth L1 of the groove 20. If it is less than 1.5 times, the base material sheet 20 is easily torn along the groove 20, and the handleability is inferior. The thickness of the base sheet 10 excluding the depth L1 of the groove 20 is preferably 2 mm or less. Even if it is thicker than this, no significant improvement is seen in the strength of the base material sheet 10 in handling, and it is contrary to the reduction in weight and thickness of the backlight, display device, etc. that uses this optical sheet 1, which is not preferable. .

  As a manufacturing method of the base material sheet 10, extrusion molding, press molding, 2P molding method (Photo Polymerization process), etc. can be used, for example. In this case, a thermoplastic resin such as an acrylic resin, a styrene resin, or a polycarbonate resin can be used in extrusion molding or press molding. Further, in the 2P molding method, a polyethylene terephthalate resin or the like can be used as the constituent resin of the transparent sheet, in addition to the above-mentioned resin, and a urethane acrylate ultraviolet curable resin or the like can be used as the photocurable resin. .

  In addition to the scraping printing method shown in FIG. 4, the base sheet 10 is filled with the ink 41, and a light shielding material is placed on a part of the groove forming surface of the base sheet 10 and applied with a scraper. The light shielding material may be filled only on the opening end side of the groove while spreading. Examples of the scraper used in these methods include a rubber squeegee and a metal doctor blade. The rubber hardness of the rubber squeegee (according to JIS K6253) is preferably about 60 to 90.

  According to these filling methods, the filling amount of the ink 41 into the groove 20 can be adjusted by the pressing force of the scraper. As long as the opening end 22 is covered with the ink 41 and the air layer 42 remains on the bottom 23 side, the ink filled from the opening end 22 does not need to reach the bent portion 26 or the bent amount. 26 may be exceeded, but from the viewpoint of stabilizing the filling amount, it is preferable that the ink 41 is filled from the opening end 22 of the groove to the bent portion 26.

  As the ink 41, an ink containing a light-shielding material with an ultraviolet curable resin, a solvent-based adhesive, a thermosetting resin, or the like as a base material can be used. The refractive index of the base material of the ink 41 is preferably lower than the refractive index of the prism row 11. Thereby, in the optical sheet 1, the light use efficiency can be improved by total reflection even on the wide end 43 side of the light shielding portion filled with the ink cured product 41 '.

  As the light shielding material in the ink 41, dyes, carbon particles, colored pigments, white pigments, light diffusing materials, metal particles, and the like can be used. In particular, when the optical sheet 1 of the present invention is used for a transmissive screen, a reflective screen or the like, it is preferable to use carbon particles as a light-shielding material, and a brightness enhancement sheet for a backlight, a viewing angle control sheet, a peek When used in a prevention sheet or the like, it is preferable to use a pigment, a diffusion material, metal particles, or the like.

  When the light-shielding material is a pigment or carbon particles, the preferred particle size is 1 to 20 μm. If it is smaller than this, the light shielding property may be insufficient. If it is larger than this, the particles themselves act like foreign matters, and there may be a problem such as clogging of ink supply means or scraping means (not shown). is there.

  The concentration of the light-shielding material in the ink 41 is preferably higher from the viewpoint of the light-shielding property, but if the concentration of the light-shielding material is too high, the ink coating property is inferior, so that it is about 0.5 to 20% by weight. It is preferable.

  The viscosity of the ink 41 is preferably relatively high from the point of forming the air layer 42 in the groove 20, for example, 1000 mPa · sec or more (25 ° C., E-type viscometer, 0.5 rpm), particularly 1500 mPa. -It is preferable to set it as second or more.

  In the optical sheet manufacturing method of the present invention, after the ink 41 is filled in the groove 20, the optical sheet 1 is obtained by curing the ink 41 by ultraviolet irradiation, drying, heating, or the like according to the type of the ink 41.

  If necessary, the optical sheet of the present invention may be provided with a prism row, a lenticular lens row, etc. on the surface opposite to the surface where the light shielding portion is formed. In this case, the lenticular lens row is provided with the light shielding portion 40. You may make it correspond with arrangement | positioning. Moreover, you may arrange | position the optical sheet, the coloring sheet, the glare-proof sheet, etc. which disperse | distributed the light diffusing particle | grains to the single side | surface or both surfaces of the optical sheet 1 of this invention. Further, when the optical sheet of the present invention is used as a reflective sheet, a reflective layer may be provided on the surface of the prism row 11 on the light shielding part forming surface side.

  The optical sheet obtained by the method of the present invention can be mounted on the front surface of a display panel such as a plasma display or a liquid crystal display, or used as a rear projection screen or a reflection screen. In that case, the mounting direction of the optical sheet may be such that the groove filled with the ink is directed to the viewer side or the image light source side in accordance with purposes such as improving external light contrast and controlling the viewing angle. The optical sheet can be used as a diffusivity control sheet for a backlight of a liquid crystal display or the like.

Example 1
A base sheet 10 having the cross section shown in FIG. 8 is produced by extrusion molding using a polycarbonate resin, ink is filled into the grooves by a scraping printing method, and the ink is cured by ultraviolet irradiation to produce a viewing angle control sheet. did.

  Here, the dimensions of the surface shape of the base sheet 10 and the ink specifications were as follows.

Base sheet sheet groove width W1 at the bent portion: 12.6 μm
Groove width W2 at the open end: 30 μm
Bottom chamfering width W3: 1μm
Groove pitch W4: 100 μm
Groove depth L1: 81.4 μm
Distance L2 between the open end of the groove and the bent portion: 30 μm
Angle θ1: 90 ° between the first surface and the thickness direction of the base sheet
Angle θ2 formed by the second surface and the thickness direction of the base sheet: 7 °
Angle θ3: 7 ° between side surface of opening end and thickness direction of base material sheet
Base sheet thickness L3: 300 μm

Ink light shielding material: 5% by weight of carbon particles
Binder resin: Urethane acrylate UV curable resin Viscosity: 2000 mPa · s (25 ° C., E-type viscometer, 0.5 rpm)

  When the cross section of the obtained viewing angle control sheet was observed with an optical microscope, the ink was filled only in the portion from the open end of the groove to the bent portion.

  The optical sheet of the present invention is useful as a brightness distribution control sheet for displays and screens, a light diffusion sheet, a diffusion control sheet, a peep prevention sheet, a contrast improvement sheet, and the like.

It is a perspective view of an optical sheet. It is a perspective view of a base material sheet. It is sectional drawing of the sequence direction of the groove | channel of a base material sheet. It is explanatory drawing of the manufacturing method of an optical sheet. It is sectional drawing of the sequence direction of the groove | channel of a base material sheet. It is sectional drawing of the sequence direction of the groove | channel of a base material sheet. It is sectional drawing of the sequence direction of the groove | channel of a base material sheet. It is sectional drawing of the sequence direction of the groove | channel of a base material sheet.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical sheet 2 Viewing angle control layer 10 Base material sheet 11 Prism row | line | column 20 Groove 21 Side surface 22 Open end part 23 Bottom part 24 1st surface 25 2nd surface 26 Bending part 27 Side surface 40 of opening end part of a groove | channel 40 Light-shielding part 41 Ink 41 ′ Ink cured product 42 Air layer 43 Wide end 44 of the light shielding portion Narrow end 45 of the light shielding portion Surface of the light shielding rod wide end side D Thickness direction of the base sheet θ1 The first surface is the thickness direction of the base sheet Angle formed by θ2 Angle formed by the second surface in the thickness direction of the base sheet θ3 Angle formed by the side surface of the opening end in the thickness direction of the base sheet L1 Groove depth L2 Distance between the opening end of the groove and the bent portion L3 Base sheet thickness W1 Groove width at bent part W2 Groove width at open end W3 Chamfer width at bottom W4 Groove pitch

Claims (6)

An optical sheet having a viewing angle control layer in which prism rows and light shielding portions are alternately arranged,
In the cross section of the light shielding portion in the arrangement direction, the light shielding portion is formed such that the end on one side of the optical sheet is wider than the end on the other side (hereinafter, the wider end is the wider end and the narrower end is smaller). Is called the narrow end),
In the cross-section, the side surface of the light-shielding portion has a bent portion including a first surface on the wide end side and a second surface on the narrow end side, and an angle between the first surface and the thickness direction of the optical sheet is θ1, second Θ1> θ2 where θ2 is an angle between the surface and the thickness direction of the optical sheet,
The light-shielding part is an optical sheet characterized in that the wide end side is made of a cured ink and the narrow end side is an air layer. By filling the ink from the groove forming surface side of the base sheet in which the prism rows and the grooves are alternately arranged, the prism rows and the light shielding portions have a viewing angle control layer in which the light shielding portions are arranged in the grooves. A method for producing an optical sheet in which the opening end side is made of an ink cured product and the bottom side of the groove is an air layer,
As a base sheet, in the cross section in the groove arrangement direction, the width of the opening end of the groove is formed wider than the width of the bottom of the groove,
In the cross section, the side surface of the groove has a bent portion including a first surface on the opening end portion side and a second surface on the bottom portion side, and an angle between the first surface and the thickness direction of the base sheet is θ1, second A manufacturing method characterized by using a material satisfying θ1> θ2 where θ2 is an angle between the surface and the thickness direction of the base sheet.   The manufacturing method according to claim 2, wherein the substrate sheet has θ3 <θ1 when θ3 is an angle formed by a side surface of the opening end of the groove and the thickness direction of the substrate sheet in a cross section in the arrangement direction of the grooves. .   The manufacturing method according to claim 3, wherein the base sheet has a first surface substantially parallel to a sheet surface of the base sheet.   The manufacturing method according to any one of claims 2 to 4, wherein the substrate sheet has a groove width of 1 to 200 µm at the bent portion.   6. The manufacturing method according to claim 2, wherein the base sheet has a groove depth of 20 to 500 [mu] m and a distance between the opening end of the groove and the bent portion of 5 to 100 [mu] m.

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