JP2010156892A - Optical element manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical element manufacturing method which suppresses complexity of a manufacturing process and facilitate manufacturing of the optical element. <P>SOLUTION: The optical element manufacturing method includes a pressurization step of: overlaying an optical sheet 410 including a light-transmissive flat base part 412 and a plurality of light-transmissive protrusions 415 formed on one surface 417 of the base part, on a light-transmissive base material 421; then, pressurizing the optical sheet against a light shielding layer 423 for shielding light provided on the base material; and then, breaking the light shielding layer by the protrusions to form light-transmissive apertures. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an optical element used in an illumination device (backlight) for illuminating a transmissive display device such as a liquid crystal display device from the back, or an optical element arranged on the front surface of the transmissive display device to control a viewing angle. The present invention relates to a manufacturing method.

  In recent years, liquid crystal displays have become the mainstream of image display devices and are used in a wide range of devices such as mobile phones, digital cameras, and liquid crystal televisions. Although the size of the liquid crystal display varies depending on these devices, the main configuration is almost the same regardless of the size, and the liquid crystal display includes a liquid crystal panel including liquid crystal and a backlight as a light source. In the liquid crystal display, various optical elements are used or devised in order to adjust the viewing angle and brightness of the light by diffusing and condensing the light from the backlight.

  In addition, liquid crystal, especially nematic liquid crystal, has a polarization function that varies depending on the incident angle of light, so that it does not have sufficient modulation effect on light that is incident in an oblique direction and is emitted in an oblique direction. In such a case, a decrease in contrast and an inversion phenomenon occur.

  As a method for avoiding this, Patent Document 1 and Patent Document 2 describe a method in which light from a backlight is condensed, collimated, incident on a liquid crystal panel, emitted from the liquid crystal panel, and then diffused. Has been.

  As an optical element for condensing light from a backlight, Patent Document 2 discloses an array of lenticular lenses or microlenses and a light-shielding portion that reflects light to other portions by an opening that allows light to pass in the vicinity of its focal plane. What is formed is disclosed. As a method for forming such an opening and a light-shielding portion, Reference 2 discloses a portion in which the adhesiveness of the adhesive photosensitive resin layer is lost by self-alignment using the light collecting action of the lens itself, and the adhesiveness is lost. A method of forming a light-shielding material at a site other than the above is disclosed.

  On the other hand, the optical element of Patent Document 1 is arranged between a liquid crystal panel and a backlight, and has openings arranged along the surface on the backlight side, and light incident through the openings is converted into parallel light by total reflection. Therefore, the optical element includes a projecting microcollimator having a light output surface larger in area than the light input surface and a lens that further collimates the light that has passed through the microcollimator. The light from the backlight reaches the optical element through the opening, and the openings are arranged at intervals corresponding to the microcollimator and the lens, and a light-shielding layer that blocks light is located between the openings. Buried.

A method of forming a light shielding layer on an optical sheet having a light input surface and a light output surface with different areas, such as this micro-collimator, and condensing / diffusing light using total reflection is used. Patent Document 3 describes a method in which light-shielding pigment particles are filled in grooves between the portions and excess particles are removed with a brush or the like.
International Publication No. WO95 / 14255 Pamphlet JP 2000-171617 PR JP-A-62-245239

  However, the method of forming the light-shielding layer only in the part where the adhesiveness of the adhesive photosensitive resin layer is lost by self-alignment of the lens and the adhesiveness is not lost is limited to one to several light-shielding fine particles. However, it is difficult to form a thick film, and thus there is a problem that sufficient light shielding performance cannot be obtained. Alternatively, by applying this method, a transferable ink containing a light-shielding pigment is prepared in advance, an adhesive adhesive layer is formed using self-alignment, and the light-shielding pigment is included in the pattern of the adhesive layer. However, there is a method of transferring the ink to form the opening and the light shielding layer. However, even in this method, if the pigment concentration in the ink is increased or the thickness of the ink layer is increased, there is a problem that the image is not resolved. there were.

  In addition, the method of filling the groove between the protrusions serving as the openings with ink (light-shielding fine particles) and removing the excess ink requires that the excess ink be scraped and removed after the ink is filled. Yes, the manufacturing process tends to be complicated. In addition, there is a risk that the quality of the product may be deteriorated due to factors such as ink remaining on the protrusion corresponding to the opening or the protrusion being damaged when the ink is removed. The present invention has been made in view of such problems, and an object thereof is to provide an optical element manufacturing method that is easy to manufacture.

  In order to achieve the above object, an optical element manufacturing method according to the present invention provides an optical sheet comprising a flat base that transmits light and a plurality of protrusions that transmit light provided on one surface of the base. A pressing step of forming an opening that allows light to pass by pressing the light shielding layer that blocks light provided on the substrate by the optical sheet, and rupturing the light shielding layer by the protrusion. Have.

  In the optical element manufacturing method of the present invention, the projecting portion is arranged in accordance with the position of the opening while forming the opening that allows light to pass by the breakage of the light shielding layer by the protrusion, so that the complexity of the manufacturing process can be suppressed, Easy to manufacture.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the embodiments described below, members having functions common to the respective embodiments are denoted by similar reference numerals, and redundant description is omitted.

<First Embodiment>
FIG. 1 is a diagram for explaining the outline of the optical element manufacturing method, FIG. 2 is a diagram for explaining the manufacturing process of the optical element in detail, and FIG. 3 is an application example of the optical element manufactured according to the first embodiment. It is a figure explaining.

  Referring to FIG. 1, the optical element manufacturing method according to the embodiment includes an optical sheet 410 including a flat base 412 that transmits light and a plurality of protrusions 415 that transmit light provided on one surface 417 of the base 412. An optical sheet forming step to be formed;

  The optical element manufacturing method also includes a buffer layer 422 that is softer and more transparent than the protrusions 415 on a diffusion plate 421 (corresponding to a base material) that transmits light, and a light shielding material that is made of a material more brittle than the buffer layer 422 on the buffer layer 422. Forming a layer 423.

  The diffusing plate 421 supplies the uniformly surface-emitting light to the optical sheet 410. The buffer layer 422 has adhesiveness, and is, for example, PSA (Pressure Sensitive Adhesive). The light shielding layer 423 is formed by dispersing fine particles such as titanium oxide and silicon oxide in a binder such as a transparent resin. The thickness t of the light shielding layer 423 is several μm to several tens μm, and is smaller than the height H of the protrusion 415 (H> t). The light shielding layer 423 has a diffuse reflectance of 50 to 90%. Here, the light shielding layer 423 blocks most of the light but does not completely block light and does not transmit at all.

  After the optical sheet forming step and the light shielding layer forming step, the optical element manufacturing method stacks the optical sheet 410 on the diffusion plate 421, presses the light shielding layer 423 provided on the diffusion plate 421 with the optical sheet 410, and 415 includes a pressing step of breaking the light shielding layer 423 to form an opening through which light passes.

  As shown in FIG. 2A, in the optical sheet forming step, a plurality of protrusions 415 are formed on the surface 417 of the base 412, and a well-known ultraviolet curable resin (hereinafter simply referred to as a UV resin) is used as a matrix (not shown). The resin is cured and formed by irradiating with ultraviolet rays. The optical element 410 may integrally form the base 412 and the plurality of protrusions 415 by melt extrusion.

  2B and 2C illustrate a method for forming the buffer layer 422 and the light shielding layer 423 over the diffusion plate 421. FIG. As shown in FIG. 2B, a film sheet is prepared in which an adhesive buffer layer 422 and a light-shielding layer 423 are formed between a pair of release films 424 and 425 in advance. Next, as shown in FIG. 2C, the film sheet is bonded to the diffusion plate 421 using the adhesiveness of the buffer layer 422 while peeling the release film 424 on the buffer layer 422 side.

  As shown in FIG. 2D, in the pressing step, after the release film 425 is peeled off, the light shielding layer 423 is broken by the protrusions 415 and the protrusions 415 are bitten into the buffer layer 422. By the pressing step, the optical sheet 410 and the diffusion plate 421 are integrated, and the optical element 400 is formed.

  The protrusion 415 penetrates the light shielding layer 423. The broken light shielding layer 423 enters between the protrusions 415 and 415 together with the buffer layer 422. Between the protrusion 415 and the protrusion 415, an air layer 405 (hereinafter simply referred to as an air layer 405) is formed between the light shielding layer 423 and the optical sheet 410.

  If the light shielding layer 423 is soft like the buffer layer 422, the light shielding layer 423 may be deformed along the outer shape of the projection 415 when the projection 415 presses the light shielding layer 423, and may cover the projection 415 serving as an opening. Therefore, it is preferable that the light shielding layer 423 is fragile and easily breaks when pressed by the protrusion 415.

  In the first embodiment, the buffer layer 422 and the light shielding layer 423 are prepared in advance between the release films 424 and 425 and bonded to the diffusion plate 421. However, the present invention is not limited to this. Instead, the buffer layer 422 and the light shielding layer 423 may be formed in this order directly on the diffusion plate 421. In addition, buffer layers 422 are formed on both sides of the light shielding layer 423 for the purpose of preventing splashing of the light shielding layer 423 crushed when the light shielding layer 423 is broken and preventing the corners of the tip of the projection 415 from being damaged. Also good. At this time, it is desirable that the refractive index of the transparent buffer layer on the optical sheet 410 side is smaller than the refractive index of the protrusion 415 so as not to impair the total reflection of light on the side surface of the protrusion 415.

  The effects of the first embodiment will be described.

  Since the optical element manufacturing method arranges the protrusions 415 in accordance with the positions of the openings while forming the openings through which light passes due to the breakage of the light shielding layer 423 by the protrusions 415, the complexity of the manufacturing process can be suppressed, Easy to manufacture.

  Further, since the optical element manufacturing method causes the protrusion 415 to bite into the buffer layer 422 that is softer than the protrusion 415, damage to the protrusion 415 can be prevented, and as a result, an optical element 400 of good quality can be manufactured.

  FIG. 3 shows a usage pattern of the optical element of the first embodiment.

  As shown in FIG. 3A, the optical element 400 manufactured by the optical element manufacturing method according to the first embodiment is disposed between the liquid crystal panel 50 and the backlight 52 and is made uniform by the diffusion plate 421. By making the light 53 of the backlight incident, it is possible to collect the light 54 in the front direction and supply the light 54 with improved brightness to the liquid crystal panel 50.

  The optical element 400 shown in FIG. 3B is disposed downstream of the liquid crystal panel 50 in the emission direction of the light 51, and the light 51 is incident from the optical sheet 410, thereby widening the viewing angle of the light 51.

  In the embodiment shown in FIG. 3B, the light shielding layer 423 is a light shielding layer 423 that absorbs light such as black in order to improve contrast in a bright room. For example, the light-absorbing light-shielding layer 423 is obtained by dispersing fine particles such as carbon, black resin beads, and black pigment in a binder such as a transparent resin. Further, the substrate 421 may be a transparent plate or a transparent film instead of the diffusion plate. As the transparent plate or transparent film, plastic plates such as acrylic resin, styrene resin, polycarbonate resin, and polyester resin, and films and glass plates can be used. This transparent plate or transparent film may be formed with a known anti-glare layer (AG), non-reflective layer (AR), low reflective layer (LR), etc. on its outgoing side surface.

<Second Embodiment>
4 is a diagram for explaining the outline of the optical element manufacturing method, FIG. 5 is a diagram for explaining the optical sheet forming process, FIG. 6 is a diagram for explaining the pressing process, and FIG. 7 is a partially enlarged view of the optical element. FIG.

  Referring to FIG. 4, the optical element manufacturing method according to the embodiment includes an optical sheet 110 including a flat base 112 that transmits light and a plurality of protrusions 115 that transmit light provided on one surface 117 of the base 112. An optical sheet forming step to be formed; The optical sheet 110 has a plurality of convex lenses 111 (corresponding to lenses) at positions corresponding to the protrusions 115 of the other surface 116 different from the surface 117 of the base 112.

  The optical element manufacturing method also includes a buffer layer 122 that is softer and transparent than the protrusion 115 on the diffusion plate 121 (corresponding to the base material) that transmits light, and a material that is more brittle than the buffer layer 122 on the buffer layer 122. Forming a light shielding layer 123. The diffuser plate 121, the buffer layer 122, and the light shielding layer 123 can be the same as those described in the first embodiment.

  After the optical sheet forming step and the light shielding layer forming step, the optical element manufacturing method stacks the optical sheet 110 on the diffusion plate 121, presses the light shielding layer 123 provided on the diffusion plate 121 with the optical sheet 110, and 115 has a pressing step of breaking the light shielding layer 123 to form an opening through which light passes.

  As shown in FIG. 5, the optical sheet forming step includes a lens forming step for forming a plurality of convex lenses 111 on the surface 116 of the base 112, and a cured layer for forming a UV resin layer 113 that is cured by light on the surface 117 of the base 112. Forming step. In the optical sheet forming step, the UV resin layer 113 is irradiated with light through the convex lens 111 to form a cured portion 114 formed by curing the UV resin layer 113, and the UV resin layer 113 different from the cured portion 114 is removed. And a protruding portion forming step in which the hardened portion 114 is the protruding portion 115.

  As shown in FIG. 5A, in the lens formation step, the base 112 and the plurality of convex lenses 111 are formed by irradiating an ultraviolet curable resin (hereinafter simply referred to as UV resin) with ultraviolet rays or by melt extrusion molding. Are integrally formed.

  The plurality of convex lenses 111 are, for example, a one-dimensional lenticular lens or a two-dimensional microlens array. The array of the microlens array may be a square array arranged vertically and horizontally, a hexagonal close-packed array arranged in a hexagonal shape without a gap, or a random array. After the lens formation step, UV resin is applied to the surface 117 in the cured layer formation step.

  As shown in FIG. 5B, in the curing step, the UV resin applied to the surface 117 is cured by self-alignment. That is, the UV resin layer 113 is irradiated with ultraviolet rays 10 through the convex lens 111, and the portion corresponding to the convex lens 111 in the UV resin layer 113 is cured. The irradiation direction of the ultraviolet rays 10 is substantially perpendicular to the surfaces 116 and 117 of the base 112, and the focal point 15 of the convex lens 111 is located on the UV resin layer 113.

  As shown in FIG. 5C, in the protrusion forming step, the UV resin layer 113 different from the cured part 114, that is, the uncured UV resin is washed away with, for example, a solvent to form the protrusions 115.

  The protrusions 115 formed in this way become one-dimensional protrusions when the plurality of convex lenses 111 are one-dimensional lenticular lenses, like the convex lens 111, and in the case of a two-dimensional microlens array. After all, it is arranged two-dimensionally.

  As shown in FIG. 6, in the pressing step, the light blocking layer 123 is broken by the protrusion 115 and the protrusion 115 is bitten into the buffer layer 122. By the pressing step, the optical sheet 110 and the diffusion plate 121 are integrated, and the optical element 100 is formed.

  The second embodiment has substantially the same effect as the first embodiment.

  Unlike the embodiment, an adhesive pressure-sensitive adhesive layer is formed by utilizing self-alignment of the lens 111 at a position corresponding to the surface 117 between the protrusions 115 on the surface 117, and the pattern of the pressure-sensitive adhesive layer is shielded from light. It is also possible to transfer the ink containing the pigment to form the opening and the light shielding layer (transfer method). However, in this method, if the pigment concentration in the ink is increased, the resolution may be lowered.

  On the other hand, in the present embodiment, the light shielding layer 123 is formed between the protrusion 115 and the protrusion 115 while the light blocking layer 123 is broken by the protrusion 115 to form an opening through which light passes without being transferred. Even when the concentration of the light-shielding fine particles contained in the light-shielding layer 123 is increased, the resolution is good.

  Unlike the embodiment, the protrusion 115 and the opening can be aligned by a mechanical method. However, with such a method, it is difficult to achieve both high definition and large area. On the other hand, in the present embodiment, the projection 115 is arranged in accordance with the position of the opening while forming the opening through which light is transmitted by the breakage of the light shielding layer 123 by the projection 115. It is easy to achieve both.

  As shown in FIG. 7, in the optical element 100, the light scattered by the diffusion plate 121 passes through the projection 115 and the convex lens 111 and is collimated in the front direction by the lens action. Therefore, the optical element 100 is disposed between a liquid crystal panel including liquid crystal and a backlight as a light source, and light from the backlight is made incident from the diffusion plate 121, so that light with improved brightness in the front direction is liquid crystal. Can supply the panel.

  The air layer 105 may not be provided. However, if the air layer 105 is provided as in the embodiment, light that is totally reflected is generated due to a difference in refractive index between the light shielding layer 123 and the air layer 105. Compared to the above, the light shielding property of the light shielding layer 123 is preferably increased. Further, since the light totally reflected on the side surface 118 of the protrusion 115 is generated due to the difference in refractive index between the protrusion 115 and the air layer 105, the ratio of the light incident on the adjacent convex lens 111 (see the dotted line in FIG. 7) is set. Can be reduced.

  In the optical element manufacturing method according to the embodiment, when the protrusion 115 is bitten into the buffer layer 122, the broken light shielding layer 123 is pressed between the protrusion 115 and the protrusion 115 so as to be pushed by the buffer layer 122. Therefore, in the optical element 100, the light shielding layer 123 protrudes toward the optical sheet 110. When light is reflected by the light shielding layer 123, only complete scattered reflection rarely occurs, and scattered reflection having no directionality and regular reflection (specular reflection) are often mixed. In the optical element 100, since the light shielding layer 123 protrudes toward the optical sheet 110, the ratio of the directional component perpendicular to the boundary surface between the buffer layer 122 and the diffusion plate 121 in the regular reflection component of the scattered reflection. However, it increases compared with the case where the light shielding layer 123 and the base 112 are substantially parallel. As a result, since the number of reflections can be suppressed and light can be emitted from the projection 115, the light utilization efficiency is improved.

<Third Embodiment>
FIG. 8 is a diagram for explaining another optical element manufacturing method according to the third embodiment.

  As shown in FIG. 8, the third embodiment is substantially the same as the second embodiment, but in the curing step of the second embodiment, the focal point 25 of the convex lens 211 is positioned farther than the UV resin layer 213. Different from the second embodiment. Therefore, a protrusion 215 having a trapezoidal cross section can be formed, and in the pressing step, the light shielding layer 223 is broken by the protrusion 215 having a shape that tapers toward the tip. Therefore, in addition to the effect of the second embodiment, there is an effect that the force for pressing the protrusion 215 can be reduced in the pressing step.

  FIG. 9 shows how the optical elements of the second and third embodiments are used.

  As shown in FIG. 9A, the optical element 100 (200) manufactured by the optical element manufacturing method according to the second and third embodiments is an optical manufactured by the optical element manufacturing method according to the first embodiment. Similar to the element 400, the light 53 of the backlight is incident between the liquid crystal panel 50 and the backlight 52, and is made uniform by the diffusion plate 121 (221), thereby condensing the light in the front direction. Thus, the light 54 with improved brightness can be supplied to the liquid crystal panel 50.

  Further, as shown in FIG. 9B, the optical element 100 (200) manufactured by the optical element manufacturing method according to the second and third embodiments is arranged downstream of the liquid crystal panel 50 in the emission direction of the light 51. Then, by making the light 51 incident from the lens 111 (211), the viewing angle of the light 51 can be widened. The light shielding layer 123 (223) is an absorptive light shielding layer similar to the light shielding layer 423 in the optical element 400 manufactured by the manufacturing method according to the first embodiment, and the base material 121 (221) is also the first embodiment. Similarly to the substrate 421 in the optical element 400 manufactured by the manufacturing method according to, a transparent plate or a transparent film may be used.

<Fourth embodiment>
FIG. 10 is a view for explaining an optical element manufacturing method according to the fourth embodiment, and FIG. 11 is a plan view of the optical sheet according to the fourth embodiment viewed from the protrusion side.

  The optical element manufacturing method according to the fourth embodiment is substantially the same as that of the second embodiment. In the second embodiment, the plurality of convex lens elements 111 is either a one-dimensional lenticular lens or a two-dimensional microlens array. However, the fourth embodiment is limited to only a two-dimensional microlens array. Moreover, a hardening process differs from 2nd Embodiment.

  FIG. 10A is a perspective view of a microlens array sheet used in the fourth embodiment. In the microlens array sheet of this example, convex lenses 311 are arranged in a hexagonal close-packed manner. The direction in which the convex lenses 311 are sequentially arranged is 31, and the direction in which every other lens is alternately arranged is 32. Hereinafter, the microlens array sheet used in the fourth embodiment will be described with an example in which the convex lenses 311 are arranged in a hexagonal close-packed manner, but the fourth embodiment is not limited to this, and a square arrangement or a random arrangement is used. It can also be applied to arrangements and the like.

  As shown in FIG. 10B, in the curing step of the fourth embodiment, the ultraviolet rays 30 are diffused and irradiated in one direction 31 along the surface of the UV resin layer 313, or the angle at which the ultraviolet rays 30 are irradiated is changed. Then, ultraviolet rays are irradiated stepwise in one direction 31 along the surface of the UV resin layer 313.

  By such irradiation, for example, as shown in FIG. 11A, a protrusion 315A having an elliptical cross-sectional shape in a plane parallel to the surface 317 of the base 312 is formed. The major axis of the ellipse is along direction 31. Alternatively, as shown in FIG. 11B, a protrusion 315B connected along the direction 31 is formed. Since each of the protrusions 315A and 315B has such a shape, the viewing angle is different between the direction 31 and the direction 32 perpendicular thereto. That is, the optical element manufacturing method according to the fourth embodiment has an effect of manufacturing optical elements having different viewing angles in two directions in addition to the effects of the second embodiment.

  The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims. For example, in the first embodiment, if the buffer layer 422 has a sufficient thickness, the cross-sectional shape of the protrusion 415 may be a triangle with a sharp tip. Further, in FIG. 3B regarding the usage mode, when the liquid crystal panel 50 and the optical element 400 are bonded to each other with the base 412, the optical element 400 itself does not need to be self-supporting. You may do it.

It is a figure for demonstrating the outline | summary of the optical element manufacturing method. It is a figure for demonstrating the detailed optical element manufacturing method. It is a figure for demonstrating the utilization form of an optical element. It is a figure for demonstrating the outline | summary of the optical element manufacturing method which concerns on 2nd Embodiment. It is a figure for demonstrating the optical sheet formation process which concerns on 2nd Embodiment. It is a figure for demonstrating a press process. It is the elements on larger scale of an optical element. It is a figure for demonstrating the optical element manufacturing method which concerns on 3rd Embodiment. It is a figure which shows an example when an optical element is applied to a liquid crystal display. It is a figure for demonstrating the optical element manufacturing method which concerns on 4th Embodiment. It is a top view of the optical sheet which concerns on 4th Embodiment seen from the protrusion side.

Explanation of symbols

10, 20, 30 UV,
15, 25 focus,
31 one way,
50 LCD panel,
52 Backlight,
100, 400 optical elements,
105, 405 air layer,
110, 210, 410 Optical sheets 111, 211, 311 Convex lenses (corresponding to lenses),
112, 212, 312, 412 base,
113, 213, 313 hardened layer,
114 curing part,
115, 215, 315A, 315B, 415 protrusion,
116, 216, 316, 416 Base surface (corresponding to one surface),
117, 217, 317, 417 Base surface (corresponding to other surface),
121, 221 and 421 diffuser plate (corresponding to the base material),
122, 222, 422 buffer layer,
123, 223, 423 Light-shielding layers.

Claims (4)

  An optical sheet having a flat base that transmits light and a plurality of projections that transmit light provided on one surface of the base is overlaid on the base that transmits light, and is provided on the base by the optical sheet. The optical element manufacturing method which has a press process which presses the light shielding layer which interrupts the emitted light, breaks the said light shielding layer with the said protrusion, and forms the opening part which lets light pass.   A buffer layer softer and transparent than the protrusion on the base material, and a step of forming the light shielding layer made of a material more brittle than the buffer layer on the buffer layer, and the pressing step includes: The optical element manufacturing method according to claim 1, wherein the light shielding layer is broken by the protrusions, and the protrusions are bitten into the buffer layer.   The optical element manufacturing method according to claim 1, wherein the protrusion has a shape that tapers toward a tip.   The optical element manufacturing method according to claim 1, wherein the optical sheet has a plurality of lenses at positions corresponding to the protrusions on another surface different from the one surface of the base portion.