WO2013159687A1

WO2013159687A1 - Light guide sheet comprising optical micro structure and manufacturing method thereof

Info

Publication number: WO2013159687A1
Application number: PCT/CN2013/074512
Authority: WO
Inventors: 路志坚; 杨星; 张亚荣; 杨云胜
Original assignee: 博昱科技（丹阳）有限公司
Priority date: 2012-04-24
Filing date: 2013-04-22
Publication date: 2013-10-31
Also published as: CN102621624A

Abstract

A light guide sheet comprising an optical micro structure and a manufacturing method thereof. The light guide sheet comprises at least one light incident surface (107) and the optical micro structure (102) formed after polymerization of photo-polymerizable material, and the position of the optical micro structure (102) is randomly distributed within at least one region on surface of the light guide sheet, and the density of the micro structure (102) gradually varies in at least one direction. The method for manufacturing the light guide sheet comprises: a mask plate pattern is designed, which is randomly distributed within at least one region and whose density gradually varies in at least one direction; a photo-polymerizable material mixture coating is provided on a light guide sheet substrate; the material mixture of the coating is selectively polymerized by using energy radiation with the mask plate pattern, and unpolymerized material mixture on the coating is removed. The application range of the light guide sheet comprises a backlight source of a liquid crystal display and a LED (Light Emitting Diode) illumination module.

Description

Light guide sheet containing optical microstructure and manufacturing method thereof

Technical field

Field of the Invention This invention relates to the field of liquid crystal display backlights and LED illumination, and more particularly to a light guide for liquid crystal display backlights and LED illumination assemblies and methods of fabricating the same.

Background technique

The light guide in the edge-lit backlight of a liquid crystal display is one of the most important optical components in a liquid crystal display. The light guide plate passes light from a light source located on a side surface of the light guide sheet through a scattering point formed on the back surface of the light guide sheet, a reflection surface adjacent to the back surface of the light guide sheet, and a diffusion film placed on the light exit surface of the light guide sheet. The function of the condensing film becomes a surface light source that is relatively uniformly hooked to the back surface of the liquid crystal display panel and has a certain angular distribution. The scattering point on the back side of the light guide sheet is usually a scattering point containing a diffusion component formed by printing, such as screen printing. The scattering dots thus formed play a very important role in changing the light incident from the side surface into a relatively uniform surface light source, but have a large influence on the light utilization efficiency. At the same time, due to limitations in manufacturing processes and optical performance, the resulting scattering points are difficult to meet the requirements of high-performance liquid crystal displays, such as smart phones and tablets. Although inkjet printing, injection molding and other methods are being studied for the production of scattering points in light guides, high equipment cost and process requirements, and the resulting optical structure has lower optical properties, limiting the wide application of these technologies. .

Summary of the invention

The light guide sheet and the manufacturing method thereof of the present invention overcome the defects of the production methods such as screen printing, ink jet printing, injection molding, and the corresponding light guide sheet, and provide a light guide sheet containing the optical microstructure and a manufacturing method thereof.

The technical solution of the present invention is achieved by: a light guide sheet containing an optical microstructure, comprising a substrate and a plurality of microstructures formed by polymerizing the photopolymerizable material on the surface of the substrate, the light guide sheet The substrate has optically transparent properties. Suitable substrate materials include polymethyl methacrylate (PMMA), polycarbonate (PC), polyvinyl alcohol (PVA), and polyterephthalic acid (PET). The light guide sheet substrate has at least one light incident surface, and light emitted from a light source adjacent to the light incident surface passes through the light incident surface into the light guide sheet. In at least one region of the light guide sheet of the present invention, the positions of the microstructures are regularly or randomly distributed, and the density (the number of microstructures per unit area) gradually increases as the distance from the light surface increases. The microstructures in the light guide sheet may comprise microprisms having a triangular cross section. The orientation of the microprisms can be randomly or nearly randomly distributed over a range of angles on either side of the set direction. The microprisms randomly or nearly randomly oriented within a certain angular range cause the light emitted from the corresponding region of the light guide sheet to have a uniform distribution in the space and to some extent accumulate in the normal direction of the light guide sheet. The microstructure on the light guide sheet may include sides that form a symmetrical or asymmetrical angle with the bottom surface. Such as light guide When the upper microstructure comprises a side surface forming an asymmetrical angle with the bottom surface, an angle formed by one side and the bottom surface of the microstructure may be an obtuse angle greater than 90°, and the corresponding microstructure is a microstructure inclined to one side. Such a tilted optical microstructure can more effectively control the direction and distribution of light emerging from the light guide for light entering the light guide in a particular direction.

The microstructure on the light guide of the present invention may further comprise a pyramid or a top-cut pyramidal optical microstructure. The microstructure on the light guide of the present invention may comprise an optical microstructure comprising a bottom surface and a non-planar curved surface. The intersection of the microstructure and one surface of the light guide sheet is a gradual non-linear line. The microstructure with a non-planar curved surface has no distinct boundaries to distinguish the various portions of the sides of the microstructure. The intersection of the microstructure and the surface of the light guide sheet may be circular, elliptical, or other suitable shape. The optical microstructures on the light guide sheet containing non-planar curved surfaces may be spherical, ellipsoidal, parabolic, tapered, top truncated cones or other suitable shaped optical microstructures.

The light guide sheet of the present invention may comprise a microstructure having a smooth surface. The smooth surface of the optical characteristics when the light is incident on the surface, the light mainly from the surface of the refraction, the light entrance and exit directions to follow the description of the incoming and outgoing light Snell's law (Snel l Law) ₀ of the present invention The light guide sheet or optical microstructure that may comprise a rough surface having a further surface microstructure. The optical feature of the rough surface is that when light is incident on the surface, the effect of the surface on the light comprises scattering. Corresponding to the incident light in a single direction, the outgoing light is distributed over a range of angles.

The microstructure of the present invention is formed by polymerizing a photopolymerizable material after receiving energy radiation. The microstructure in the light guide sheet is not limited to a shape, size, orientation, surface features, and positional distribution. The light guide sheet of the present invention may comprise microstructures of different shapes, sizes, orientations, surface features or positional distributions. Microstructures of different shapes, sizes, orientations, surface features or positional distributions may be included in the same region or in different regions of the light guide sheet.

The spatial distribution and angular distribution of light emerging from the light guide of the present invention can be adjusted by the shape, size, orientation, surface characteristics and positional distribution of the microstructure. The random distribution of microstructure locations and orientations eliminates or reduces interference and diffraction phenomena due to regular alignment and orientation.

The method of fabricating the light guide sheet of the present invention comprises designing an optical mask comprising a light transmissive opening and a light blocking portion. The position distribution and shape of the light-transmitting opening correspond to the positional distribution and shape of the microstructure in the light guide sheet. The light-transmissive opening may be an opening having the same transmittance at all, or an opening having an increasing or decreasing transmittance in one or more directions, or an opening having an increasing or decreasing transmittance from the center in one or more directions (grayscale) Or Gray Scale light opening). One side of the mask corresponds to the light incident surface of the light guide sheet. Transmit light in at least one area of the reticle The positions of the openings are randomly distributed or arranged according to a set rule, and the density gradually increases with an increase in the distance from the side of the light incident surface of the corresponding light guide sheet.

At least one region of the reticle may comprise a rectangular light transmissive opening, and the orientation of the long sides of the rectangular light transmissive opening may be randomly or nearly randomly distributed over a range of angles. In at least one region of the reticle, the light transmissive opening may be circular, or the edges may be other non-linear shapes, such as an elliptical shape. The mask of the present invention typically comprises a substrate substrate which may be of high flatness such as quartz glass, soda lime glass, or borosilicate glass. A layer of metallic chromium is deposited on the surface of the glass by sputtering or evaporation. Metallic chromium has the effect of blocking the passage of energy radiation such as ultraviolet light, visible light or electron beams. An optical photoresist or an electron beam resist is coated on the chrome layer, and the photoresist is exposed to an optical or electron beam by a design pattern, and then etched to obtain a mask having a light-transmitting and light-blocking portion. The reticle containing the reticle pattern may be a flexible mask. The flexible mask may comprise a polyester base layer having good dimensional stability; an emulsion layer, such as a silver salt emulsion layer, providing a light transmissive and light blocking pattern; and a tie layer promoting adhesion between the emulsion layer and the polyester base layer Focus; protective layer, protect the silver salt emulsion layer from damage. The emulsion means any substance which can be applied to a polyester base layer and which can constitute a light-transmitting and light-blocking pattern.

The fabrication of the light guide of the present invention begins with the preparation of a material mixture. The material mixture comprises one or more photopolymerizable components plus one or more photoinitiators. Alternatively, if a photopolymerizable material that does not require a photoinitiator is used, the photoinitiator can be omitted. "Photopolymerizable" materials or "photopolymerizable" materials refer to materials that are polymerized or cured by energy radiation, such as ultraviolet light, visible light, electron beams, and the like. The mixture may also comprise one or more non-photopolymerizable material components, such as solid particles, liquids, and the like. A substrate such as polycarbonate (PC), polymethyl methacrylate (PMMA), polyvinyl alcohol (PVA) or polyterephthalic acid (PET) is placed on the mask. An index matching liquid such as isopropyl alcohol may be applied between the substrate and the reticle. The material mixture is applied to the substrate by knife coating, slot die coating or other suitable coating method to form a coating. The thickness of the coating can be between 5 microns and 500 microns, preferably between 15 microns and 100 microns. The material mixture may be first coated on the substrate of the light guide sheet, and the light guide sheet substrate coated with the material mixture is placed on the mask. The quenched or nearly collimated energy radiation, such as ultraviolet light, visible light, electron beam, etc., is used to selectively polymerize the material mixture in the coating through the light transmissive opening of the reticle and form a solid structure corresponding thereto. Additional materials such as antistatic agents, anti-scratches, leveling agents, antifoaming agents, and the like may also be included in the material mixture. Next, the solvent is selectively polymerized using a solvent such as methanol, acetone, water, isopropanol or other suitable solvent or solvent mixture. The material mixture is coated to remove unpolymerized portions of the coating to form a microstructure corresponding to the reticle pattern and the material mixture employed. By designing an appropriate reticle pattern and preparing a suitable material mixture, microstructures having different shapes and surface features can be formed to produce different optical effects such as refraction, scattering, etc. of the incident light.

According to the present invention, the light emitted by the light source enters the light guide sheet from the light incident surface, passes through the optical microstructure formed on at least one surface of the light guide sheet, the reflective surface adjacent to the back surface of the light guide sheet, and the light exit surface of the light guide sheet. The action of the upper diffusion film and the condensing film becomes a surface light source that is relatively uniformly hooked to the back surface of the liquid crystal display panel and has a certain angular distribution. According to the optical properties of the microstructure on the surface of the light guide sheet and the spatial and angular distribution of the surface light source, the diffusion film or the light collecting film above the light exit surface of the light guide sheet may be omitted. The optical microstructures fabricated on at least one surface of the light guide sheet have high optical performance and can meet the requirements of high-performance liquid crystal display backlights and LED lighting components, smartphones, and tablets.

DRAWINGS

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 depicts an exemplary light guide sheet of the present invention comprising a microprism formed by polymerizing a photopolymerizable material and randomly oriented.

Figure 2 depicts the orientation angle of the microprisms on an exemplary light guide of the present invention.

Figure 3 depicts another example light guide comprising a microprism formed by polymerizing a photopolymerizable material and randomly oriented.

Figure 4 depicts the orientation angle of the microprisms on another example light guide sheet of the present invention.

Figure 5 depicts an exemplary optical microstructure on a light guide of the present invention.

Figure 5 (a) depicts a cross section of an exemplary optical microstructure in the XZ plane.

Figure 5 (b) depicts a cross section of another example optical microstructure in the XZ plane.

Figure 6 (a) depicts a pyramidal optical microstructure on a light guide of the present invention.

Figure 6 (b) depicts a top-cut, pyramidal optical microstructure on the light guide of the present invention.

Figure 7 depicts a third example light guide sheet of the present invention comprising a microstructure in which a photopolymerizable material is formed by polymerization and comprising a curved surface.

Figure 8 (a) depicts an exemplary optical microstructure having a curved surface on a light guide sheet of the present invention.

Figure 8 (b) depicts a cross section of an exemplary optical microstructure having a curved surface on the light guide sheet of the present invention in the XY plane.

Figure 9 (a) depicts an exemplary tapered optical microstructure on a light guide of the present invention. Figure 9 (b) depicts a top-off conical optical microstructure on the light guide of the present invention.

Figure 10 is a SEM photograph of an example of a microstructure having a fine top surface and a non-planar curved surface. Figure 11 depicts an example reticle pattern for making the light guide of the present invention.

Figure 12 depicts an example reticle pattern for making a corner-lit light guide.

Figure 13 depicts another example reticle pattern for making the light guide of the present invention.

Figure 14 depicts an exemplary method of fabricating a light guide of the present invention.

Figure 15 depicts an example light source module incorporating the light guide of the present invention.

detailed description

As shown in Fig. 1, the light guide sheet of the present invention comprises a substrate 101 and a plurality of microstructures 102. The light guide sheet substrate 101 has a -Z surface 103 and a +Z surface 104 which are parallel to the XY plane, a _Y side surface 105 and a +Υ side surface 106 which are parallel to the XZ plane, and a -X side surface 107 and +Χ parallel to the pupil plane. Side 108. The microstructures 102 are located on the - surface of the crucible. A light source composed of the LED array 109 is placed near the -X side 107 of the light guide. The -X side of the light guide is therefore referred to as the light incident surface.

The light guide sheet substrate 101 has optical transparency characteristics. Suitable materials for the substrate include polycarbonate (PC), polymethyl methacrylate (PMMA), polyvinyl alcohol (PVA), and polyterephthalic acid (PET). However, the substrate material is not particularly limited. Any material having optically transparent properties can be used as the substrate material.

As shown in Fig. 1, the microstructures 102 on the side surface 103 of the light guide sheet-Z are triangular prisms having a triangular cross section. The positions of the microprisms are randomly distributed on the side of the light guide sheet -Z, but the density (the number of microprisms per unit area) gradually increases as the distance from the entrance surface increases. The longitudinal direction of the microprism is set to the orientation of the microprism, which can be represented by the angle β between the projection 201 of the microprism shown in Fig. 2 on the XY plane and the Y direction. The angles distributed on both sides of the Υ direction are distinguished by positive and negative. The orientation of the micro-prism of the example light guide sheet is randomly or nearly randomly distributed within a certain angle range on both sides of the Υ direction, for example, on both sides of the Υ direction -3 (Γ30° angle range is random or nearly random distribution. Microprism orientation angle The sum of β is the average orientation of the microprisms in the light guide. The average orientation of the microprisms can be along the x-direction, ie the sum of the orientation angles is zero, or in other directions, ie the sum of the orientation angles is not zero.

Light that is emitted from the light source 109 and enters the light guide sheet by the light incident surface 107 may be refracted or scattered by the microstructure, from the microstructure-containing surface 103, or from the -Ζ surface 103. Surface 104 exits the light guide. The spatial distribution and angular distribution of light emerging from the light guide can be adjusted by the shape, size, orientation, surface characteristics, and positional distribution of the microstructure. The position is randomly distributed, and the density gradually decreases with the light entering the surface. The microprisms that are added and randomly oriented within a certain angular range cause the light emitted from the light guide sheet to have a uniform distribution in the space and to some extent accumulate in the normal direction of the light guide sheet. The random distribution of microstructure locations and orientations eliminates or reduces interference and diffraction phenomena due to regular alignment and orientation.

Depending on the configuration of the light source, or the need for spatial and angular distribution of light emerging from the light guide, the position of the microprisms in the example may be distributed according to a set rule, including the equidistant distribution, microprisms. The density is linear or exponential with the distance from the glossy surface, or other suitable law. In this example, the microprisms can be oriented in a set direction, such as the long side of the microprism along the Y direction.

Figure 3 depicts another example light guide of the present invention. The example light guide sheet includes a substrate 301 and a plurality of microstructures 302. The light guide sheet substrate 301 has a -Z surface 303 and a +Z surface 304 which are parallel to the XY plane, a -Y side 305 and a +Y side 306 which are parallel to the XZ plane, and -X sides 307 and +X which are parallel to the YZ plane. Side 308. The example light guide sheet substrate has a light incident side 309 between the -X side 307 and the +Y side 306. The light incident surface 309 can be a flat or curved surface, and the LED light source 310 is placed in front of the light incident surface 309. Light emitted from the LED light source enters the light guide through the light incident surface 309. The microstructures 302 are located on the -Z surface 303 of the light guide. The position of the microstructure is randomly distributed on the surface of the light guide sheet -Z, but the density (the number of microprisms per unit area) gradually increases as the distance from the entrance surface increases. The orientation of the microstructure on the light guide of the present example can be represented by the angle a between the projection 401 of the microstructure shown in Fig. 4 on the XY plane and the tangent of the arc of the circle centered on the projection 402 of the LED light source on the XY plane. The angles distributed on the outside and inside of the arc are distinguished by positive and negative. The magnitude and positive and negative of the orientation angle of the microstructure on the light guide of the present example are within a set angle range, for example, on the sides of the corresponding arc tangent -3 (Γ30° angle range, random or nearly random distribution. Microstructure orientation angle The sum of the average orientation angles. According to the characteristics of the light guide sheet, the LED light source and the light guide light, the average orientation angle of the microstructure can be zero degrees or other angles set.

FIG. 5 depicts an example optical microstructure 500. The exemplary optical microstructure includes a bottom surface 501, a front side 502, a back side 503, and end faces 504 and 505. The front side 502 and the back side 503 of the exemplary optical microstructure are joined by an arcuate surface 506. The bottom surface 501 is parallel to the XY plane and is located on the side of the light guide sheet_Z. Figure 5 (a) depicts the cross section of the microstructure in the XZ plane. The bottom surface 501, the front side surface 502, the rear side surface 503, and the section line of the arcuate surface 506 parallel to the XZ plane are denoted by 501a, 502a, 503a and 506a, respectively. In this example, the angle formed by the cut lines 501a and 502a and the angle formed by the cut line 501a and the cut line 503a (3⁄4 are both acute angles (<90°). For example, = (3⁄4, sides 502 and 503 are perpendicular to the bottom surface) Direction (Z) is symmetrical. Figure 5(b) depicts another optical microstructure containing front and back sides as shown at 502 and 503 in Figure 5, but with the front and back sides being asymmetrically inclined with respect to the direction perpendicular to the bottom surface (Z direction), Corresponding sides and cut lines parallel to the XZ plane are shown as 502b and 503b. The section line 501b and the section line 506b are respectively cut lines formed by the bottom surface 501 and the plane parallel to the XZ of the top surface 506 as shown in FIG. However, in the example microstructure, the angle formed by the line 501b and the line 502b is an acute angle (<90°), and the angle formed by the line 501b and the line 503b (3⁄4 is an obtuse angle (>90°). The exemplary optical microstructure is in fact a slanted microstructure that can more effectively control the direction and distribution of light emerging from the light guide for light entering the light guide in a particular direction.

Figure 6 (a) depicts an example optical microstructure of a pyramid shape. The optical microstructure includes a bottom surface 601a, sloped sides 602a, 603a, 604a, and 605a. The sloping sides converge to form a top 606a. Figure 6 (b) depicts a top-cut truncated pyramidal example optical microstructure. The microstructure includes a bottom surface 601b parallel to the XY plane, inclined sides 602b, 603b, 604b, 605b, and a top surface 606b.

Figure 7 is a third example of the light guide sheet of the present invention. The light guide sheet includes a substrate 701 and a plurality of microstructures 702. The light guide sheet substrate has a -Z surface 703 and a +Z surface 704 parallel to the XY plane, a -Y side 705 and a +Y side 706 parallel to the XZ plane, and -X side 707 and +X side parallel to the YZ plane 708. Microstructure 702 is located on -Z surface 703 of the substrate. The -X side 707 is the light incident surface of the light guide sheet. 709 is an array of LED light sources adjacent to the light incident surface of the light guide. In the example light guide sheet, the positions of the microstructures are randomly distributed on the surface of the light guide sheet -Z, and the density (the number of microstructures per unit area) gradually increases as the distance from the light surface increases. The microstructure has a non-planar curved surface with no distinct dividing lines to distinguish the sides. The intersection of the microstructure 702 and the -Z surface 703 is a gradual non-linear line.

Depending on the configuration of the light source, or the need for spatial and angular distribution of light emerging from the light guide, the position of the microstructures in the example may be distributed according to a set rule, including the equidistant distribution, microstructure The density is linear or exponential with the distance from the glossy surface, or other suitable law. The example light guide may alternatively comprise a second microstructured region, for example, a microstructured region adjacent to the LED array source. The second microstructure region may contain microstructures of different shapes, sizes, orientations, surface features or positional distributions from the first microstructure region. The second microstructured region eliminates or reduces the unevenness of the light and dark phases produced by the discrete LED sources.

Figure 8 (a) depicts an exemplary optical microstructure 800 containing a curved surface. The microstructure includes a bottom surface 801 and a non-planar curved surface 802. The curved surface 802 can be a spherical, ellipsoidal or parabolic one section. The curved surface 802 can be a smooth surface or a rough surface with a further surface microstructure. The intersection of the surface of the microstructure 802 parallel to the XY plane is a gradual non-linear line. Figure 8(b) is a cross section of the microstructure 800 on the XY plane, the cut line of which is shown as 803. The cut lines on the XY plane of the microstructures on the light guide sheet may be circular, elliptical, or other suitable shapes.

Figure 9 (a) depicts a tapered optical microstructure 900a. The microstructure includes a bottom surface 901a, a non-planar curved surface 902a and a top portion 903a. Figure IX (b) is a truncated conical optical microstructure. The microstructure includes a bottom surface 901b, a non-planar curved surface 902b, and a top surface 903b. The non-planar curved surface and top surface may be smooth surfaces or rough surfaces with fine structures. Figure 10 is a SEM photograph of a microstructure example of a top surface and a non-planar curved surface having a fine structure. The top surface of the microstructure 1001 contains a point-like uneven microstructure 1002, and the non-planar curved surface contains a linear uneven microstructure 1003 radially along the curved surface of the microstructure. When light passes through a rough surface having a fine structure, scattering due to a rough surface is generated, and the light emitted from the light guide sheet of the present invention has an effect of uniform distribution.

It is worth mentioning that the microstructures suitable for the light guide of the present invention are not limited to the microstructures described in the examples. Any microstructure containing a surface that refracts or scatters light can be used in the practice of the present invention. The microstructure in the light guide sheet is not limited to a microstructure having a shape, a size, an orientation, a surface feature, and a positional distribution. The light guide sheet of the present invention may have different microstructures of different shapes, sizes, orientations, surface features, and positional distributions. .

The method for fabricating the light guide sheet of the present invention comprises the following steps.

An optical mask is designed, which has a light-transmissive opening and a light-blocking portion through which light cannot pass. The position distribution and shape of the light-transmitting opening correspond to the positional distribution and shape of the microstructure in the light guide sheet. Figure 11 depicts an example mask comprising a light transmissive opening 1101 separated by a light blocking portion 1102. The light-transmissive opening may be an opening having the same transmittance at all, or an opening having an increasing or decreasing transmittance in one or more directions, or an opening having an increasing or decreasing transmittance in one or more directions from the center (grayscale) Or Gray Scale light opening). One side of the mask 1103 corresponds to the light incident surface of the light guide sheet, and the position of the light transmission opening 1101 is randomly distributed, and the density gradually increases with the distance from the side 1103 of the light incident surface of the corresponding light guide sheet.

The light-transmissive opening 1101 in the example mask of FIG. 11 is rectangular, and the orientation of the single light-transmissive opening is at an angle to the Y-direction. The angles distributed on both sides of the Y direction are distinguished by positive and negative. The orientation of the light-transmissive openings in the example mask has a random distribution over a range of angles on either side of the Y-direction, for example, in the Y-direction of both sides -3 (the range of Γ30°). The average orientation (in the direction of the Υ) The sum of the angles) can be along the Υ direction, That is, the sum of the orientation angles β of the microprisms is zero, or an angle that is not equal to zero with respect to the pupil direction. The example mask described in FIG. 11 can be used to fabricate the example light guide described in FIG.

Figure 12 depicts another example reticle for making the light guide of the present invention. The mask includes a light transmissive opening

1201, the light transmissive opening is separated by the light blocking portion 1202. The light-transmissive opening may be an opening having the same transmittance at all, or an opening having an increasing or decreasing transmittance in one or more directions, or an opening having an increasing or decreasing transmittance from the center in one or more directions (grayscale) Or Gray Scale light opening). The light-transmitting opening of the example mask has a rectangular shape, and its longitudinal direction is set to the orientation direction of the opening. The orientation of the light-transmissive opening of the example mask is distributed at a corner of the mask, as shown by 1203 in the figure, the outer side or the inner side of the circular arc, and the angle formed by the tangent of the corresponding arc at the microstructure position. Positive and negative within the set angle range, for example, on the sides of the corresponding arc tangent -3 (Γ30° angle range, random or nearly random distribution. This example mask can be used to make the slave as described in Figure 3. a light guide that enters the light incident between the X side and the +Υ side.

Figure 13 depicts another example reticle. The optical mask contains a light-transmissive opening and a light-blocking portion through which light cannot pass. The position distribution and shape of the light-transmissive opening correspond to the positional distribution and shape of the microstructure in the light guide sheet. The light shield opening 1301 of the example mask is circular, or the edge is other non-linear patterns such as an ellipse. The light transmissive openings are separated by a light blocking portion 1302. The light-transmissive opening may be an opening having the same transmittance at all, or an opening having an increasing or decreasing transmittance in one or more directions, or an opening having an increasing or decreasing transmittance from the center in one or more directions (grayscale) Or Gray Scale light opening). The side 1303 of the mask corresponds to the light incident surface of the light guide. The positions of the light-transmissive openings 1301 are randomly distributed, and the density gradually increases as the distance from the side 1303 increases. The example mask can be used to fabricate a light guide comprising microstructures as described in FIG.

It is worth mentioning that the reticle suitable for fabricating the optical sheet of the present invention is not limited to the example reticle described above. A reticle containing light transmissive openings of other shapes, sizes, orientations, and positional distributions can be used in the practice of the present invention. The reticle is not limited to a shape, size, orientation, and positional distribution of light transmissive openings, and light transmissive openings having different shapes, sizes, orientations, and positional distributions may be employed in the same reticle. The position distribution of the light-transmitting openings in the mask may be distributed according to a set rule, and the set rule includes an equidistant distribution, a density of the light-transmissive opening and a linear or exponential relationship with the distance from the light edge, or other The right rule. The second light-transmissive opening region may be included in the mask, for example, a light-transmissive opening region adjacent to the light edge. The second light-transmissive opening region may include a light-transmissive opening that is different in shape, size, orientation or position from the first light-transmissive opening region. The second light-transmissive opening region can be used to make a corresponding microstructure to eliminate il^sM, and ι, κη ^ ^ ή ή ή 暗暗暗暗 „ „ „ „ „ The reticle of the present invention typically comprises a substrate substrate. The substrate substrate may be a high flatness glass such as quartz glass, soda lime glass, or borosilicate glass. There are certain requirements for the defect density of glass, energy radiation, such as ultraviolet light, transmittance of visible light or electron beam, and temperature expansion coefficient. A layer of metallic chromium is deposited on the surface of the glass by sputtering or evaporation. Metallic chromium has the effect of blocking the passage of energy radiation such as ultraviolet light, visible light or electron beams. Applying an optical photoresist or an electron beam photoresist to the chrome layer, exposing the photoresist to an optical or electron beam method according to a design pattern, and then etching to obtain a mask having a light-transmissive opening and a light-blocking portion. . The reticle containing the reticle pattern may be a flexible reticle. The flexible mask may comprise a polyester base layer having good dimensional stability; an emulsion layer, such as a silver salt emulsion layer, providing a light transmissive and light blocking pattern; and a tie layer promoting adhesion between the emulsion layer and the polyester base layer Focus; protective layer, protect the silver salt emulsion layer from damage. The emulsion means any substance which can be applied to a polyester base layer and which can constitute a light-transmitting and light-blocking pattern.

Fig. 14 is a view showing an example of a method of manufacturing a light guide sheet of the present invention. The fabrication of the light guide begins with the preparation of the material mixture. The material mixture is a photopolymerizable material comprising one or more photopolymerizable components plus one or more photoinitiators. Alternatively, if a photopolymerizable material that does not require a photoinitiator is used, the photoinitiator can be omitted. The mixture may also comprise one or more non-photopolymerizable material components, such as solid particles, liquids, and the like. Next, a substrate 1401, such as polycarbonate (PC), polymethyl methacrylate (PMMA), polyvinyl alcohol (PVA) or polyterephthalic acid (PET) or other suitable substrate, is placed in the On the mask 1403. An index matching liquid such as isopropyl alcohol may be applied between the substrate 1401 and the mask 1403. Next, the material mixture is coated on the substrate 1401 by knife coating, slot die coating, or other suitable coating method to form a coating 1402. The thickness of the coating 1402 can be between 5 microns and 500 microns, preferably between 15 microns and 100 microns. Alternatively, a material mixture may be applied to the substrate of the light guide sheet, and the light guide sheet substrate coated with the material mixture may be placed on the mask. Next, the collimated or nearly collimated energy radiation, such as ultraviolet light, visible light, electron beam, etc., is selectively passed through the light-transmissive opening of the mask to selectively polymerize the material mixture in the coating 1402 and form a corresponding Solid structure. Additional materials such as antistatic agents, anti-hatch agents, leveling agents, antifoaming agents, and the like may also be included in the material mixture. Next, the selectively polymerized material mixture coating is washed using a solvent such as methanol, acetone, water, isopropanol or other suitable solvent or solvent mixture to remove unpolymerized portions of the coating. Forming a microstructure corresponding to the reticle pattern and the material mixture employed. By designing an appropriate mask pattern and preparing a suitable material mixture, it can be formed into different shapes and large The microstructure of small, oriented, and surface features produces different optical effects such as refraction and scattering of incident light. Figure 15 depicts an exemplary light source module incorporating the light guide of the present invention. The light incident surface (-X side) of the light guiding sheet 1501 of the present invention is provided with an LED array 1502. Adjacent to the surface of the light guide sheet (-Z surface) containing the microstructure is a reflective layer 1504. The reflective layer can be a specularly reflective layer, or a Lambertian reflective layer. Light emitted from the LED array enters the light guide through the light incident surface (-X side), and is irradiated onto the light guide on the light guide sheet or directly emitted from the light exit surface (+Z surface) of the light guide sheet, or from the microstructure containing The surface (-Z surface) exits and is emitted by the reflective layer and enters the light guide again, and is emitted from the exit surface of the light guide. The shape, size, orientation surface feature and position distribution of the microstructure in the light guide sheet 1501 can make the light emitted from the light exit surface evenly distributed, or at the same time, the effect of concentrating the outgoing light to the normal direction of the light source of the light sheet. . The microstructure in the example light guide is located on the -Z surface adjacent to the reflective surface 1504, and the microstructure in the light guide may be located on the exit surface +Z surface away from the reflective surface 1504. The light-emitting surface of the light guide sheet 1501 may be placed on one side or one or more layers of other optical films, such as a diffusion sheet, a prism sheet, or a diffusion-concentrating and concentrating integrated film, as shown in FIG. Excellent diffusion or concentrating effect.

The above description is only illustrative of specific embodiments of the invention and is not intended to limit the invention. Various changes and modifications may be made within the spirit and scope of the invention, but are intended to be included within the scope of the invention.

Claims

Claim

What is claimed is: 1. A light guide sheet comprising an optical microstructure, wherein at least one surface of the light guide sheet comprises a plurality of microstructures formed by polymerization of a photopolymerizable material, wherein: the position of the microstructure is guided At least one region on at least one surface of the light sheet is randomly or regularly distributed, and the density gradually changes in at least one direction.

2 . The light guide sheet comprising an optical microstructure according to claim 1 , wherein: the microstructure comprises a bottom surface and a plurality of surfaces, and the bottom surface is located on a surface of the light guide sheet substrate; With a certain orientation, the orientation angles of the microstructures are randomly or nearly randomly distributed over a set range of angles.

The light guide sheet containing an optical microstructure according to claim 2, wherein: at least two sides of the microstructure form different angles from the bottom surface; at least one angle is greater than 90° Obtuse angle.

4. The light guide sheet comprising an optical microstructure according to claim 1, wherein: the microstructure comprises a bottom surface and a surface; the bottom surface is located on a surface of the light guide sheet substrate, and the microstructure surface is Non-planar curved surface, and there is no obvious dividing line to distinguish each side, the intersection of the microstructure and the surface of the substrate is a gradual non-linear line.

5. A light guide comprising an optical microstructure according to claim 4, wherein: said microstructure surface is a portion of a sphere or a portion of an ellipsoid or a portion of a paraboloid.

6. The light guide sheet comprising an optical microstructure according to claim 1, wherein: the surface or at least one side surface of the microstructure is a smooth surface, or the surface or at least one side of the microstructure is contained A rough surface of fine structure.

7. The light guide sheet comprising an optical microstructure according to claim 1, wherein: at least one region on at least one surface of the light guide sheet has different shapes, sizes, orientations, and surface features. Or a microstructure of positional distribution.

8. A method of fabricating a light guide according to claim 1, comprising: designing and fabricating a mask having a plurality of light transmissive openings, the position of the light transmissive opening in at least one region of the mask Randomly or according to a set regular distribution, the density gradually changes in at least one direction;

Providing a coating of a photopolymerizable material mixture on the light guide sheet substrate;

Irradiating the coating of the material mixture through the mask with energy radiation to selectively polymerize the photopolymerizable material; Removing the unpolymerized photopolymerizable material remaining after irradiating the mask with the energy radiation, thereby forming a position randomly or in a predetermined pattern in at least one region of the light guide sheet, and the density gradually changes in at least one direction. Structure area.

9. The method of fabricating a light guide according to claim 8, wherein: the light-transmissive opening in at least one region of the mask comprises a rectangular opening, and the orientation of the rectangular opening is random or nearly random within a certain angular range distributed.

10. The method of fabricating a light guide according to claim 8, wherein: at least one of the regions of the mask comprises a light-transmissive opening having a non-linear shape.

A method of fabricating a light guide sheet according to claim 10, wherein: the edge of the non-linear shape of the light-transmitting opening included in at least one of the regions of the mask is circular or elliptical.

12. The method of fabricating a light guide according to claim 8, wherein: at least one of the regions of the mask has light transmissive openings of different shapes, sizes, orientations or positions.