JPH07281181A - Production of planer optical element - Google Patents

Abstract

PURPOSE:To produce a microlens array in which a light shielding zone accurately aligned by an extremely easy method is combined, by applying or laminating a resin compsn. which is transparent for visible light and is hardened with light beams or electron beams on a light shielding layer formed on a substrate and irradiating the substrate with hardening energy rays through the opposite surface to the surface where the shielding layer is formed. CONSTITUTION:After a shielding layer 2 which has a pattern corresponding to the desired optical element and absorbs and/or reflects hardening energy rays is formed on a substrate 1, a resin compsn. which is hardened with light beams or electron beams and is transparent for visible light is applied or laminated on this shielding layer. Then the substrate 1 is irradiated with hardening energy rays through the opposite surface of the substrate 1 to the surface where the shielding layer 2 is formed. As for the material to form optical elements such as a microlens 3 and microprism, a hardening resin compsn. transparent for visible light is used. As for the hardening energy rays, UV rays or electron beans are preferably used considering that the range to select a resin and that the device can be rather generally obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a planar optical element such as a microlens array and a microprism array.

[0002]

2. Description of the Related Art As a method for manufacturing a planar optical element in which microscopic solids such as microlenses and microprisms are formed on a transparent substrate, a female die having a shape desired in advance is prepared, and the substrate and the die are prepared. A method of filling and curing a transparent resin or the like between the two is generally practiced.

In the case of a very small solid having a size of a few tens of μm or less, a so-called positive photoresist, that is, a photosensitive resin of a type in which a photosensitive portion is decomposed and solubility in a solvent is improved, is subjected to pattern exposure, After developing to obtain a three-dimensional shape such as a columnar shape, it is heated and melted by utilizing the thermoplasticity due to the positive type, and is molded into a dome-shaped three-dimensional shape that is obtained by utilizing the surface tension at the time of melting (for example, Meas.
Sci. Technol. 1, No. 8 p. 759-
766 (1990) and the like) are used.

A method for obtaining a desired solid by changing the etching intensity for each part using an electron beam or a laser beam (for example, Opt. Lett. 6, p. 613-).
615 (1981)) has also been proposed.

On the other hand, the resin composition which is cured by a light ray or an electron beam (hereinafter referred to as curing energy ray) is selectively cured in a pattern projected on a substrate to obtain a desired planar pattern. It is widely known that it is used in negative photoresists and the like.

In a rear projection type projector screen or the like, a black light-shielding band (black stripe) is formed by printing black paint on a molded lens sheet for the purpose of improving image contrast on a lenticular lens screen for displaying an image. May be combined.

Further, in order to reduce the viewing angle dependence of the liquid crystal display (a phenomenon in which the display quality changes depending on the viewing direction of the liquid crystal display, and in some cases, it is difficult to read the display content), the microlens array is used as a liquid crystal It has been proposed to mount it on the surface of a display, and it is disclosed in JP-A-6-
27454 proposes an optical element for a liquid crystal display, which is a combination of a microlens array and a light-shielding band and has a good display quality.

[0008]

However, even if any of the conventional methods is used, the light-shielding band (black stripe,
Or a black matrix) is a planar array of optical elements (hereinafter, may be simply referred to as optical elements) such as microlenses and microprisms having a small size of about several tens of μm, which are accurately combined at predetermined positions. It was very difficult to obtain (array).

That is, such a light-shielding band exhibits its function only when it has an accurate positional relationship with an optical element such as an individual lens or a prism. However, the formation of the light-shielding band and the formation of the optical element are as follows. In the case where the respective conventional optical elements are formed by completely independent separate steps, it is extremely difficult to align them because the individual optical elements are minute.

In particular, when an attempt is made to form these sheet-like optical elements on the surface of a plastic sheet or plastic film (hereinafter sometimes simply referred to as a film), the size of the film changes due to environmental changes such as temperature and humidity. Since it is large, it is virtually impossible to form the light-shielding band and the optical elements such as the microlenses by the conventional method and accurately align their positions.

Therefore, according to the present invention, the above-mentioned drawbacks can be solved and a planar optical element such as a microlens array or a microprism array in which light-shielding bands accurately aligned are combined can be prepared by an extremely easy method. Is provided.

[0012]

In order to solve the above-mentioned problems, the present invention is a method for producing a planar optical element on a transparent flat plate substrate by a resin composition which is cured by a curing energy ray. After providing a blocking layer that absorbs and / or reflects (hereinafter, simply referred to as blocking) a curing energy ray having a shape corresponding to the pattern of the optical element required for, the layer is cured by light rays or electron beams. A method for producing a planar optical element, characterized in that a resin composition transparent to visible light is applied or laminated, and a curing energy ray is irradiated from the side opposite to the side on which the blocking layer of the substrate is formed. It is a thing.

In the present invention, an optical element such as a microlens array or a microprism array is made of a cured product of a resin composition (hereinafter, simply referred to as a curable resin composition) which is cured by a curing energy ray. To be

That is, the curable resin composition applied or laminated on the substrate has a shape corresponding to the desired pattern of the optical element formed on the substrate before the curable resin composition is applied or laminated. A cured portion is obtained according to the transmission intensity distribution of the curing energy ray of the barrier layer that blocks the curing energy ray of.

For this reason, if the blocking layer is formed as a light-shielding band corresponding to each optical element, a planar shape in which the position of each optical element and the light-shielding band is perfectly matched without any special operation is required. One of the most important points of the present invention is that an optical element can be obtained.

In the present invention, the transparent flat plate substrate means a transparent flat plate-like substrate, and examples thereof include a glass plate, a plastic sheet, a plastic film, and the like. In order to improve the adhesiveness and the adhesiveness with, it is also preferable that a so-called easy adhesion treatment such as a primer coating treatment or a plasma discharge treatment is performed. Of these, the effect of the present invention is great when the material is a transparent plastic sheet or film which is generally inferior to a glass plate in terms of dimensional stability.

In the present invention, the material forming the optical elements such as microlenses and microprisms is a curable resin composition transparent to visible light. As the curing energy ray, ultraviolet rays or electron rays are preferably used from the viewpoint of the selection range of the resin and the fact that the device is relatively commonly obtained. Further, ultraviolet rays are preferable because the shape and material of the blocking layer for blocking the curing energy rays can be selected in a wide range and can be easily obtained.

Here, the curable resin composition is a resin composition containing as a main component a monomer or prepolymer (oligomer) which initiates polymerization by the generation of radicals or ions, and when cured by ultraviolet rays. A photopolymerization initiator that generates radicals or ions by being irradiated with ultraviolet rays is added.

The monomers and prepolymers include unsaturated polyester type, acrylic type, ene / thiol type and the like, but acrylic type monomers and prepolymers are widely used because of their wide selection range of curing speed and physical properties of cured products. Is preferred.

As the acrylic type prepolymer, there are polyester acrylate, polyether acrylate, urethane acrylate, epoxy acrylate, etc., and various selections can be made according to desired characteristics (adhesion to substrate, refractive index, mechanical properties of cured product, etc.). You can

In addition to the above substances, the curable resin composition may contain various additives for controlling the properties before, during or after curing. An ultraviolet absorber can be mentioned as an example of such an additive.

It is widely known that the addition of an ultraviolet absorber to the curable resin composition improves the weather resistance after curing, but when ultraviolet rays are used as the curing energy rays, the cured product, that is, It is also a factor that controls the shape of the optical element.

The ultraviolet absorber preferably contains any one of a benzotriazole type, a benzophenone type, a benzoate type and a salicylic acid ester type, and further contains a benzotriazole type ultraviolet absorber as a main component. It is most preferable that a large effect can be obtained with a small amount of addition.

The addition amount of the ultraviolet absorber can be appropriately adjusted depending on the characteristics of the ultraviolet curable resin composition used, the shape of the required optical element, the characteristics of the curing energy ray irradiation device used, etc., but is generally in the preferred range. Is in the range of 0.2 to 10 parts by weight with respect to 100 parts by weight of the ultraviolet curable resin composition.

In the present invention, the shape of the optical element can be controlled not only by the curing characteristics of the curable resin composition but also by the combination of the shape and optical characteristics of the blocking layer and the curing energy ray irradiation conditions. Therefore, the shape and characteristics of the blocking layer formed on the substrate are important factors that determine the required characteristics of the optical element.

When the shape of the optical element to be sought is rectangular in cross section in the plane perpendicular to the substrate surface such as the diffraction grating or the optical transmission line, the shape of the blocking layer is flat and the curing energy ray is It suffices that the contrast between the transparent portion and the non-transparent portion of is clear.

However, when the optical element to be sought is not a simple rectangular cross-sectional shape in a plane perpendicular to the substrate surface such as a microlens or a microprism, but a deformed body such as a triangle, a semicircle, or a semi-ellipse. It is preferable to control the shape of the barrier layer and the distribution of the curing energy ray transmittance in advance.

That is, the cross-sectional shape of the barrier layer is not flat, but the cross-sectional shape of a plane perpendicular to the substrate surface of the barrier layer is such that the width becomes narrower from the substrate surface side toward the upper portion of the barrier layer. It is preferable in that the array density of each optical element can be maximized.

The cross-sectional shape of the barrier layer is as follows.
A triangle, a trapezoid, a semicircle, an inverted T-shape, a shape surrounded by an arbitrary curve, and the like are conceivable. Among these, a triangular shape or an inverted T-shape (for example, a shape in which two sides of a triangle are depressed inward is also included. ) Is preferable.

As a method of giving a curing energy ray transmittance distribution, the shape is a single plane shape, but the curing energy ray blocking substance has a concentration distribution, and a uniform layer has a thickness distribution. Although it is possible to consider those which have been provided, and combinations thereof, it is preferable to have a distribution of the curing energy ray transmittance depending on the distribution of the thickness, from the viewpoint that precise shape control of the optical element is easy.

The effect of the present invention is most significant when the blocking layer also has a property as a light blocking band that blocks not only the curing energy ray but also the visible light, that is, the blocking layer absorbs and / or visible light. Or, when it has the property of reflecting and when forming an optical element by the curing energy ray distribution of this blocking layer, a planar optical element having a light-shielding band whose positional relationship is perfectly matched with each optical element. Can be obtained very easily.

The material for forming such a blocking layer is not particularly limited, and materials conventionally used for blocking visible light can be used. Examples include metal films such as chromium and aluminum or metal oxide films, photographic emulsions, resins containing pigments such as pigments and dyes, and the like.

In many cases, the function of the light-shielding band combined with the optical element is that, in one optical system including the planar optical element obtained according to the present invention, unnecessary light rays which adversely affect the performance of the optical system. Since it is blocking, it is preferable that the light-shielding band has a property of absorbing visible light, that is, it is black with respect to visible light.

In the method of forming a black light-shielding band for visible light, it is preferable to use a resin material having a resin component as a base material and a colorant added thereto. As the colorant, there are a pigment type and a dye type, and any of them can be used. In addition, when a dye-based material is used, since a curing energy ray such as ultraviolet rays is irradiated when forming an optical element, the fastness to sunlight measured by a method according to JIS-L-0841 is 5 or more. It is preferable to use one.

In the present invention, the method for producing the barrier layer is not particularly limited. That is, if a layer having a function of a blocking layer can be formed on a transparent substrate in a desired pattern, it can be formed by a conventionally used method of forming a desired pattern on a substrate.

To exemplify such a method, various printing methods such as an offset printing method, a gravure printing method, a flexographic printing method, photolithography for curing or removing a photosensitive resin into a desired pattern, or etching or ablation are unnecessary. Examples include a method of removing a portion.

When the blocking layer is shaped such that the cross-sectional shape of the blocking layer perpendicular to the substrate surface becomes narrower from the substrate surface side toward the upper portion of the blocking layer, It is preferable to apply or laminate a photosensitive resin layer having a curing energy ray blocking function after curing on a substrate, and then expose and cure only a desired portion and remove the uncured portion.

The planar optical element manufactured by the present invention is a member that constitutes a device for displaying an image, that is, a so-called display device, particularly a member that constitutes an observation surface of the display device, and a luminous flux traveling direction for a planar light source device. It is useful as a control member.

Specific examples of applications include an image display screen of a front projection type display or a rear projection type display for projecting and displaying an image on a screen, an observation surface member of a direct view type display for directly observing an image, and directivity. There are surface light sources.

Of these, the manufacturing method of the present invention is particularly effective for a member for a direct-view liquid crystal display in which minute lenses and prisms having a size of several tens of μm need to be arranged in a relatively large area.

As such a member, an optical element for controlling the light emitting direction of the planar light source and an optical element for reducing the viewing angle dependence of the display characteristics of the liquid crystal display (hereinafter, simply referred to as a viewing angle enlarging element) There is) etc.

As the viewing angle enlarging element, a microlens array has been proposed to control the traveling direction of the image light flux of the liquid crystal display. However, the ambient light flux such as indoor lighting is scattered and reflected by the retroreflection on the lens surface. It is considered that it is effective to combine the light-shielding band to improve the display quality because the display quality may be remarkably lowered, but there is no effective means for manufacturing such an optical element.

[0043]

EXAMPLES The present invention will be described in detail below with reference to examples, but the invention is not limited thereto.

Example 1 (1) Preparation of light-shielding band A black dye (trade name "Sancosmo Black" 9011: manufactured by Mihara Kako Co., Ltd.) 1 was added to 30 parts by weight of methyl ethyl ketone.
0 parts by weight was added and stirred until the dye dissolved. Next, polyester acrylate oligomer (trade name "KAYARAD" HX-220: manufactured by Nippon Kayaku Co., Ltd.)
50 parts by weight, acrylic monomer (trade name "light acrylate" DCP-A: manufactured by Kyoeisha Yushi Co., Ltd.) 50 parts by weight,
Thioxanthone photoinitiator (trade name "KAYACUR
E "DETX-S: manufactured by Nippon Kayaku Co., Ltd. 7 parts by weight, aromatic tertiary amine photopolymerization accelerator (trade name" KAYACUR ")
7 parts by weight of E "EPA: manufactured by Nippon Kayaku Co., Ltd.) was added and stirred until the photopolymerization initiator and the photopolymerization accelerator were dissolved.

The coating material thus obtained (this is a black coating material 1
40 μm was applied to a polyethylene terephthalate film (trade name “Lumirror”: manufactured by Toray Industries, Inc.) with a metering bar. Then, a stripe-shaped photomask shown in FIG. 3 is placed on the side opposite to the coated surface, and an energy of 10 mJ / cm ² · sec (from a jet-light type JL-2300 manufactured by Oak Manufacturing Co., Ltd.) is applied onto the photomask. UV light having an actual measurement value) was irradiated for 5 minutes.

Subsequently, the photomask was removed, the uncured portion of the coated surface was dissolved and removed with methyl isobutyl ketone, and then the product was washed with methyl alcohol and water and dried to form black light-shielding bands in a stripe shape. A light-shielding band substrate (this is a light-shielding band substrate 1) was obtained.

A part of the light-shielding band substrate 1 was cut out and the cross section was observed with an optical microscope.
It was an isosceles triangle having a size of 5 μm and a height of 15 μm as shown in FIG.

(2) Preparation of microlens array Polyester acrylate oligomer (trade name "KAYA"
RAD "HX-220: manufactured by Nippon Kayaku Co., Ltd." 50 parts by weight, acrylic monomer (trade name "light acrylate" D
CP-A) 50 parts by weight to 10 parts by weight of a photopolymerization initiator (trade name “Irgacure” 184: manufactured by Ciba Geigy), aromatic tertiary amine photopolymerization accelerator (trade name “KAYACU”).
RE "EPA: 5 parts by weight of Nippon Kayaku Co., Ltd., a benzotriazole-based ultraviolet absorber (trade name" TINUVIN ")
1 part by weight of PS: manufactured by Ciba Geigy) was added and stirred until these additives were dissolved to obtain a transparent coating material (this is referred to as transparent coating material 1) for forming a microlens.

The transparent coating material 1 is applied to the light-shielding band forming surface side of the light-shielding band substrate 1 obtained above by 30 μm by a metalling bar, and 10 mJ is applied from the opposite side of the application surface by an ultraviolet irradiation device.
Ultraviolet light having an energy (measured value) of / cm ² · sec was irradiated for 20 seconds.

Subsequently, the uncured portion of the coated surface was dissolved with methyl isobutyl ketone, washed with methyl alcohol and water, and dried to obtain a planar optical element (this is referred to as planar optical element 1).

A part of the planar optical element 1 was cut out and the cross section was observed by an optical microscope. As a result, a composite optical element in which the microlens array and the light-shielding band shown in FIG. 1 were perfectly aligned was obtained. Was confirmed.

(3) Evaluation of characteristics Super twisted liquid crystal monochrome display mounted on a commercially available personal computer (display color monochrome mode, screen size diagonally about 9 inches, number of pixels 400 × width 6)
The planar optical element prepared in (2) was attached to the observation surface side of 40, a dot pitch of 290 μm, and a backlight, with the lens forming surface inside (the liquid crystal cell side). In addition, a conventional liquid crystal display with nothing attached was prepared for comparison.

Here, the array direction of the unit lenses of the microlens array sheet was made to coincide with the horizontal direction of the screen.

The display quality thus obtained was evaluated by observing the display from the normal direction (front) of the display surface and 60 ° to the left under room lighting which is a normal use environment. Has a narrow viewing angle, and thus the display quality in the front direction is good, but the display contents cannot be read by observation from the left 60 degrees, whereas the liquid crystal display equipped with the planar optical element produced by the method of the present invention. A good display quality was obtained when observed from both the front and the left 60 degrees.

At the same time, when a liquid crystal display equipped with a microlens array prepared by a conventional method was evaluated as a comparison object, it was good to observe it from both the front and the left 60 degrees in an environment without indoor lighting. Although the display quality was obtained, the interior illumination light was scattered and reflected strongly because the light-shielding band was not formed under the room illumination which is a normal use environment, and the display quality in the front direction was particularly poor.

As described above, it was confirmed that the present invention is effective as a method for manufacturing a planar optical element for enlarging the viewing angle of a liquid crystal display.

Example 2 (1) Fabrication of planar optical element A dry film type negative photoresist (trade name “Liston”) having a thickness of 25 μm was formed on the copper foil side of a polyethylene terephthalate film to which a copper foil having a thickness of 20 μm was bonded. : Manufactured by DuPont Co., Ltd., and the photoresist layer was exposed and developed by a photomask having a pattern shown in FIG. 4 in which circular openings having a diameter of 10 μm were arranged at every 50 μm vertically and horizontally.

Next, after etching the copper foil layer by immersing it in a ferric chloride solution, the resist layer is removed,
A light-shielding band substrate having a copper foil layer as a light-shielding band (this is a light-shielding band substrate 2
I got).

When a part of the light-shielding band substrate 1 was cut out and its cross section was observed with an optical microscope, it was found that a large number of mortar-shaped holes were arranged side by side as shown in FIG.

On the obtained light-shielding band substrate 2, Example 1 (2)
A microlens array is formed by the same method as
A composite planar optical element of a light-shielding band and a microlens (this is referred to as planar optical element 2) was obtained.

A part of the planar optical element 2 was cut out and the cross section was observed with an optical microscope. As a result, a composite optical element in which the microlens array and the light shielding band as shown in FIG. Was confirmed.

(2) Evaluation of characteristics The total light transmittance of the planar optical element 2 was measured.

When the light flux was made incident from the surface on which the microlens array was formed and the transmittance to the substrate side was measured, it was 11%, but the light flux was made to enter from the substrate side and the transmittance to the side on which the microlens was formed was 2%. It was 0.8%.

From this, a planar optical element in which the positions of the light-shielding band and each lens are matched so that each lens of the microlens array has a focal point near the opening point formed in the light-shielding band is obtained. I understand.

[0065]

EFFECTS OF THE INVENTION Even if a substrate having a relatively poor dimensional stability such as a plastic film is used, a planar optical element in which a light-shielding band and an optical element group such as a microlens are perfectly aligned can be obtained by an easy method. be able to. Since such a planar optical element is virtually impossible by the conventional method,
It becomes possible to manufacture new planar optical elements such as a viewing angle widening sheet for liquid crystal displays by an industrially advantageous method.

[Brief description of drawings]

FIG. 1 is a schematic view showing an example of a cross section of a planar optical element obtained by a manufacturing method of the present invention.

FIG. 2 is a schematic view showing an example of a cross section of a barrier layer used in the manufacturing method of the present invention.

FIG. 3 is a schematic view showing an example of a photomask pattern used in the manufacturing method of the present invention.

FIG. 4 is a schematic view showing an example of a photomask pattern used in the manufacturing method of the present invention.

FIG. 5 is a schematic view showing an example of a cross section of a barrier layer used in the manufacturing method of the present invention.

FIG. 6 is a schematic view showing an example of a cross section of a planar optical element obtained by the manufacturing method of the present invention.

[Explanation of symbols]

 1: transparent substrate 2: light-shielding band 3: microlens 4: light-shielding part of photomask 5: opening of photomask

Claims (8)

[Claims] 1. A method for producing a planar optical element on a transparent flat substrate by a resin composition that is cured by a curing energy ray, wherein a curing energy ray having a shape corresponding to a desired optical element pattern is formed on the substrate. After providing a blocking layer that absorbs and / or reflects, a resin composition transparent to visible light that is cured by light rays or electron beams is applied or laminated on the blocking layer, and the surface of the substrate on which the blocking layer is formed. A method of manufacturing a planar optical element, which comprises irradiating a curing energy ray from the opposite surface side. 2. The planar shape according to claim 1, wherein a cross-sectional shape of a surface of the blocking layer perpendicular to the substrate surface is such that the width becomes narrower from the substrate surface side toward the upper portion of the blocking layer. Optical element manufacturing method. 3. The method for producing a planar optical element according to claim 1, wherein the curing energy ray is ultraviolet light. 4. The method for manufacturing a planar optical element according to claim 1, wherein the blocking layer is black with respect to visible light. 5. The method for manufacturing a planar optical element according to claim 1, wherein the planar optical element is a microlens array. 6. The method for manufacturing a planar optical element according to claim 1, wherein the planar optical element is a micro prism array. 7. The method for producing a planar optical element according to claim 1, wherein the planar optical element is for a direct-viewing type liquid crystal display. 8. The method of manufacturing a planar optical element according to claim 1, wherein the transparent flat plate substrate is a transparent plastic sheet or a plastic film.