METHOD FOR MAKING AN OPTICAL ELEMENT

Abstract

A method for making an optical element includes the steps of: coating a curable resin on a substrate so as to form a curable resin layer on the substrate; embossing the curable resin layer so as to form a plurality of micro-protrusions thereon; and exposing the curable resin layer directly to a power source so as to cure the curable resin layer.

Description

BRIEF DESCRIPTION OF THE DRAWING

Other features and advantages of the present invention will become apparent in the following detailed description of the preferred embodiments of this invention, with reference to the accompanying drawing, in which:

FIG. 1 is a schematic view to illustrate how an optical element is made using an apparatus according to a conventional method;

FIG. 2 is a fragmentary schematic sectional view of the optical element made by the apparatus shown in FIG. 1;

FIG. 3 is a fragmentary schematic sectional view to illustrate how an optical element is made using a transferring screen according to another conventional method;

FIG. 4 is a schematic view illustrating consecutive steps of a method for making the first preferred embodiment of an optical element according to this invention; and

FIG. 5 is a fragmentary schematic sectional view to illustrate how the second preferred embodiment of the optical element is made using a roller according to the method of this invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Before the present invention is described in greater detail, it should be noted that same reference numerals have been used to denote like elements throughout the specification.

FIG. 4 illustrates consecutive steps of the first preferred embodiment of a method for making an optical element 3 according to this invention. The optical element 3 can be used as a diffuser plate or a brightness-enhancing sheet for a backlight module of a liquid crystal display, a reflective plate, an optical plate for holo-photograph, a reflective plate for road use, or the like.

The optical element 3 includes: a substrate 31; and a hardened resin layer 32 formed on a surface 311 of the substrate 31 and formed with a plurality of prism-like micro-protrusions 321.

The method for making the optical element 3 includes the steps of: coating a curable resin on the substrate 31 so as to form a curable resin layer 30 on the substrate 31; embossing the curable resin layer 30 so as to form a plurality of the micro-protrusions 321 thereon; and exposing the curable resin layer 30 directly to a power source 5 so as to cure the curable resin layer 30, thereby forming the hardened resin layer 32. Hence, unlike the aforesaid conventional methods in which the curable resin layers are indirectly exposed to a power source, i.e., the power source, such as a UV light or an E-beam, is required to pass through an optical substrate before reaching the curable resin layer, the curable resin layer 30 is directly exposed to the power source 5 in the method of this invention.

The substrate 31 is free of filler, and is preferably made from a material selected from the group consisting of polycarbonate, polyester, cyclo olefin copolymer, polymethylmethylacrylate, and titanium dioxide. The substrate 31 can be transparent or opaque based on the actual requirements.

The curable resin is preferably made from a resin selected from the group consisting of acrylic, epoxy, acrylic-epoxy, polyurethane, and silicone, and preferably has a layer thickness ranging from 1 μm to 1 mm, and more preferably ranging from 50 μm to 200 μm.

Application of the curable resin can be conducted by spinning coating techniques using a Carma coater, roller coating techniques using a roller coater, or die coating techniques using a die coater. In this embodiment, the curable resin is applied to the substrate 31 by roller coating techniques.

Formation of the micro-protrusions 321 is conducted using a planar press-molding plate 4 which is formed with a micro-structure 41 having a pattern corresponding to the structure of the micro-protrusions 321.

FIG. 5 illustrates the second preferred embodiment of the method for making the optical element 3 of this invention. The method of this embodiment differs from the previous embodiment in that formation of the micro-protrusions 321 is conducted using a roller 4′ provided with an annular micro-structure 41′ corresponding to the structure of the micro-protrusions 321. A resin nozzle 6 is used for applying the curable resin onto the substrate 31 prior to the pressing by the roller 4′. The substrate 31 is driven to move in sequence through the resin nozzle 6, the roller 4′, and the power source 5.

Since the curable resin layer 30 is directly exposed to the power source 5 according to the method of this invention, the aforesaid drawbacks associated with the prior art can be eliminated.

While the present invention has been described in connection with what are considered the most practical and preferred embodiments, it is understood that this invention is not limited to the disclosed embodiments but is intended to cover various arrangements included within the spirit and scope of the broadest interpretation and equivalent arrangements.

Claims

1. A method for making an optical element, comprising: coating a curable resin on a substrate so as to form a curable resin layer on the substrate;embossing the curable resin layer so as to form a plurality of micro-protrusions thereon; andexposing the curable resin layer directly to a power source so as to cure the curable resin layer.

2. The method of claim 1, wherein coating of the curable resin is conducted using a die coater.

3. The method of claim 1, wherein the layer thickness of the curable resin layer ranges from 1 μm to 1 mm.

4. The method of claim 3, wherein the layer thickness of the curable resin layer ranges from 50 μm to 200 μm.

5. The method of claim 1, wherein the curable resin is made from a resin material selected from the group consisting of acrylic, epoxy, acrylic-epoxy, polyurethane, and silicone.

6. The method of claim 1, wherein formation of the micro-protrusions on the curable resin layer is conducted using a planar press-molding plate.

7. The method of claim 1, wherein formation of the micro-protrusions on the curable resin layer is conducted using a roller provided with an annular micro-structure corresponding to the structure of the micro-protrusions.

8. The method of claim 1, wherein the power source for curing the curable resin layer is selected from the group consisting of UV light and E-beam.