JP2008292636A - Optical sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical sheet with a light shielding layer having improved appearance quality, the light shielding layer of which can be formed all over the apexes and slopes of convex-line light shielding parts with a single process. <P>SOLUTION: The optical sheet has the convex-line light shielding parts on one surface thereof, non-light shielding parts on the surface are flat or recessed, and a groove-like recessed part is provided at a boundary between the convex-line light shielding part and the non-light shielding part, and the layer composed of a light shielding material is disposed continuously all over the surface of the convex-line light shielding part and the recessed part. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an optical sheet having a ridge light-shielding pattern on one surface, particularly a lenticular lens sheet and a contrast filter used for a transmissive or reflective screen provided in a projection display device.

  Examples of the lens sheet include a lenticular lens sheet for a transmissive screen. In general, the lenticular lens sheet is provided with a lens array for diffusing image light to the viewer side. The pitch of the lens array is fine for the purpose of refining the image, and a pitch of 0.3 mm or less and further 0.15 mm or less is required.

In order to improve the external light contrast, an external light absorbing unit (light-shielding unit) is provided at a place other than the part where the image light is collected by the lens array. As the external light absorbing portion, a method of applying black ink to a predetermined portion and printing is generally used. In order to improve the external light contrast, it is desirable to increase the area of the external light absorbing portion as much as possible.
As a technique for forming the external light absorbing section, Patent Document 1 discloses a technique of printing with a roll on the top and the slope of the external light absorbing section of the output side ridge.

  However, when the light emitting part (non-light-shielding part 1) is flat by the method of Patent Document 1, if ink is applied to the entire slope of the ridge light-shielding part 2, the ink is emitted from the light emitting part 1 as shown in FIG. The phenomenon of protrusion is likely to occur, and in that case, the problem of low light transmittance or poor appearance quality tends to occur. Further, when the boundary line between the light emitting part 1 and the external light absorbing part becomes non-uniform, there arises a problem that the appearance quality tends to be inferior. In particular, when the pitch is 0.3 mm or less, precise application of ink is difficult.

  Patent Document 2 discloses a technique in which an external light absorbing portion is provided at the top of the exit-side convex light-shielding portion, and an external light absorbing portion is also provided in a concave portion between the exit-side convex light-shielding portion and the exit-side convex lens. Has been. Patent Document 2 shows a method of applying ink to the recesses: 1) a method of filling ink only in the recesses, and 2) a method of applying ink to the entire surface including the recesses and scraping off unnecessary portions other than the recesses. Has been.

  However, Patent Document 2 does not consider application to a lens sheet in which the light emitting portion is flat or a concave lens. Further, in the method 1), it is extremely difficult when the pitch is 0.3 mm or less, and in the method 2), two or more steps of a step of printing a concave portion and a step of printing the top portion of the exit side convex light shielding portion are necessary. There is a problem that it is complicated.

JP 2003-149743 A JP 2000-147668 A

  An object of the present invention is to provide an optical sheet with a light-shielding layer that can form a light-shielding layer on the top and the entire slope surface of the ridge light-shielding part in one step, and has excellent appearance quality.

The above-described problem is an optical sheet having a plurality of ridge light-shielding portions on one surface, wherein the non-light-shielding portion on the same surface is flat or concave, and the boundary between the ridge light-shielding portion and the non-light-shielding portion The optical sheet is provided with a concave portion, and provided with a light shielding material layer connected to the convex light shielding portion and the concave portion.
The lens sheet of the present invention is used for a lenticular lens sheet, in particular, comprising a lens on the opposite side of the convex light-shielding part, and the convex light-shielding part is provided in addition to the light collecting part by the lens array. it can.

  If it is the optical sheet of this invention, a light shielding layer can be formed in the top part of a ridge light-shielding part and the whole slope in one process, and the boundary of a ridge light-shielding part and a non-light-shielding part is clarified. Therefore, an optical sheet with a light shielding layer excellent in appearance quality can be provided.

  The present invention will be described with reference to FIG. In the optical sheet of the present invention, a plurality of convex light shielding portions 2 are provided on one surface, the non-light shielding portions 1 on the same surface are flat or concave, and the convex light shielding portions 2 and the non-light shielding portions 1 A recess 4 is provided at the boundary, and a layer (light-shielding layer 3) made of a light-shielding material connected to the ridge light-shielding portion 2 and the recess 4 is provided.

  In the present invention, the light shielding layer 3 is preferably formed by applying a black ink to the top and the entire slope of the ridge light shielding portion 2 using a roll coater. Since the ink dripping from the top is blocked and accumulated like a dam in the recess 4, the boundary between the non-light-shielding part 1 (light emitting part) and the light-shielding part becomes clear. In particular, the roll knife coater shown in FIG. 7 is preferable in that the thickness of the light shielding layer 3 can be made uniform.

  The width of the recess 4 is preferably 5 to 20 μm, and the depth is preferably 5 to 20 μm. If it is smaller than this, molding may be difficult, and if it is larger than this, it may be difficult to cure the accumulated ink. The shape of the recess 4 can be a trapezoid, a rectangle, a triangle, or the like. A trapezoid as shown in FIG. 2 is particularly preferred from the viewpoint of ease of cutting of the mold, ease of releasing the molded product from the mold, and the ability to stably form the recess 4.

  It is preferable that an angle formed between the slopes on the convex light-shielding part 2 side and the non-light-shielding part 1 side of the trapezoidal concave part 4 and the screen main surface is 45 ° to 88 °. When this angle is smaller than 45 °, the boundary between the non-light-shielding part 1 and the light-shielding part tends to be unclear. If it is larger than 88 °, the production (manufacture of the mold, release of the molded product from the mold) may be difficult.

As for the shape of the ridge light-shielding part 2, it is preferable that the vertex vicinity has a curved surface shape. The curved surface shape is particularly preferably a part of a substantially elliptical shape because it is easy to manufacture and enables uniform shaping. In this case, it is preferable that the radius of curvature at the top of the ridge light shielding portion 2 is 1 mm or less.
Further, as shown in FIG. 8, the angle θ1 formed between the lowermost portion of the slope of the ridge light shielding portion 2 and the sheet main surface is 45 ° or more, and the angle θ2 formed between the top portion of the ridge light shielding portion 2 and the sheet main surface. More preferably, it is larger. Furthermore, it is more preferable that the angle formed between the lowermost part of the slope of the ridge shading part 2 and the sheet main surface is 60 ° or more and less than 90 °.

  Furthermore, it is even more preferable that the width of the ridge light-shielding portion 2 at the position of 10 μm in the sheet thickness direction from the top of the ridge light-shielding portion 2 is 80% or less with respect to the width of the lowermost portion of the ridge light-shielding portion 2. . As an example, as shown in FIG. 9, it is preferable that the width A of the ridge light shielding portion 2 at a position of 10 μm in the sheet thickness direction from the vertex of the ridge light shielding portion 2 is 150 μm or less. By forming the convex light-shielding part 2 in such a shape, it is possible to apply ink with a uniform thickness to the top and the slope of the convex light-shielding part 2.

  A typical shape of the non-light-shielding portion 1 (light emitting portion) of the present invention is a flat surface as shown in FIG. However, in actual molding, the non-light-shielding portion 1 may be concave as shown in FIG. Further, in order to form the boundary between the non-light-shielding part 1 and the recess 4 clearly, it is possible to make the non-light-shielding part 1 concave as shown in FIG. 4, and the non-light-shielding part in the present invention includes such a shape. .

  Even if the angle formed between the non-light-shielding portion 1 side slope of the trapezoidal concave portion 4 and the sheet main surface is designed to be 45 ° or more, for example, the most non-light-shielding portion of the non-light-shielding portion 1 side slope of the trapezoidal concave portion 4 is actually formed. In the vicinity of 1, the angle becomes small and the boundary may become unclear.

  If the lens sheet is thin, the lens sheet may not be self-supporting because of insufficient rigidity. Therefore, the lens sheet may be attached to the self-supporting front sheet 7 as shown in FIG. Here, if the refractive index of the translucent adhesive layer 6 is made substantially equal to that of the lens sheet, refraction and reflection at the exit surface are substantially eliminated, so that optical problems are less likely to occur.

  Further, conventionally, it has been difficult to clarify the boundary between the slope of the ridge light-shielding portion 2 and the non-light-shielding portion 1, so it is difficult to reduce the height of the ridge light-shielding portion 2. In some cases, the image light emitted in an oblique direction from 1 is blocked and the viewing angle becomes narrow. On the other hand, according to the present invention, the boundary can be made clear even if the height of the ridge light-shielding portion 2 is lowered, so that the image light emitted in the oblique direction from the non-light-shielding portion 1 is shielded as shown in FIG. The viewing angle can be widened.

  Furthermore, the present invention also has an effect of suppressing the brightness unevenness of the image caused by the molding unevenness of the incident lens 5. Since the valley 8 of the incident lens 5 shown by the circle in FIG. 10 is sharp, non-uniformity is likely to occur in transfer molding. If non-uniformity occurs in the formation of the valley portion of the incident lens 5, the emission angle of the image light that has passed through the valley portion 8 of the incident lens 5 becomes non-uniform. Observed as light and dark defects. Here, in the present invention, since there is a light shielding portion at a position closer to the incident side than the non-exiting portion 1, it is possible to block light emitted in a direction different from the direction that should be emitted. Therefore, the image light becomes a band-like or streak-like light / dark defect and is difficult to observe.

  The optical sheet of the present invention is not limited to the lenticular lens sheet used in the transmission screen described in the above example. For example, it can be used for a reflective screen. In this case, it is preferable to dispose a reflective material in the non-light-shielding portion 1. It is also useful as a contrast filter for display devices. When used as a diffusion plate for backlight, it is useful to use a reflective material as a material for forming the light shielding layer 3.

<Example 1>
Using a rubber-containing MS resin (methyl methacrylate-styrene copolymer resin), a lenticular lens sheet having a cross-sectional shape as shown in FIG. 6 was extruded. The recess 4 is trapezoidal, the bottom of the valley is 10 μm wide, the height is 10 μm, and the angle of the slope is 85 °. The ridge shading part 2 is a part of a substantially circular shape. Using the roll knife coater shown in FIG. 7 on the light exit side (shown above in FIG. 6) of the lenticular lens sheet, UV curable black ink is applied and then irradiated with UV to remove the ink. Cured. As a result, a black ink layer (light-shielding layer 3) could be formed on the top of the ridge light-shielding part 2, the slope, and the trapezoidal concave part 4. The top of the ridge light shielding part 2 and the light shielding layer 3 on the slope were 7 to 10 μm thick. In addition, the boundary between the non-light-shielding part 1 (light emitting part) and the light-shielding part was clear, and a lenticular lens sheet excellent in appearance could be manufactured.

It is a figure which shows a prior art. It is a figure which shows an example of this invention. It is a figure which shows an example of this invention. It is a figure which shows an example of this invention. It is a figure which shows an example of this invention. It is a figure which shows the cross section of the optical sheet of an example of this invention. It is a figure which shows an example of the manufacturing method of the optical sheet of this invention. It is a figure which shows (theta) 1 and (theta) 2 in the ridge light-shielding part of this invention. It is a figure which shows the width | variety A in the ridge light-shielding part of this invention. It is a figure which shows the optical path in an example of the optical sheet of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Non-light-shielding part, 2 ... Projection light-shielding part, 3 ... Light-shielding layer, 4 ... Recessed part, 5 ... Incident lens 6 ... Translucent adhesive layer, 7 ... Front plate, 8 ... Valley 21 ... Printing roll, 22 ... Nip roll, 23 ... Ink layer, 24 ... Ink reservoir 25 ... Roll knife, 26 ... Lens sheet

Claims (2)

An optical sheet provided with a plurality of ridge shading portions on one surface,
The non-light-shielding part on the same surface is flat or concave,
A groove-shaped recess is provided at the boundary between the ridge shading part and the non-shielding part,
An optical sheet characterized in that a layer made of a light-shielding material connected to the surface of the ridge light-shielding part and the concave part is provided.   The optical sheet according to claim 1, further comprising a lens on an opposite side surface of the convex light shielding portion, the lens being provided so that light condensed by the lens is incident on the non-light shielding portion. Characteristic lenticular lens sheet.

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