JP2007065126A - Micro-lens array substrate and manufacture method for micro-lens array substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a micro-lens array substrate having high light condensing characteristic, and a manufacturing method for the micro-lens array substrate. <P>SOLUTION: A micro-lens array 200 is formed on a glass substrate 102, and is equipped with many micro-lenses 202 principally composed of glass. The adjacent micro-lenses 202 are successively formed of the glass material to form the micro-lens 202. Especially, it is desirable that thickness δ between the adjacent micro-lenses 202 is 0.1μm≤δ≤200μm. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a microlens array substrate and a manufacturing method thereof.

  In a liquid crystal display device, a technique using a microlens array has been proposed to achieve high brightness and high viewing angle. According to this technology, by forming a microlens array on the back side of a transparent substrate, backlight light can be condensed so as to avoid TFT elements and black matrix formed on the transparent substrate. It is possible to increase efficiency and achieve high brightness.

  Patent Document 1 discloses a method of forming a microlens array made of glass on a glass substrate. In the method described in Patent Document 1, a microlens array is formed by forming a film of a photosensitive glass paste made of glass powder and a photosensitive resin on a substrate, and performing exposure, development, and heat treatment.

  Specifically, in the step of forming a lens pattern before heat treatment, two exposures are performed using two types of photomasks, and the lens pattern on which two steps are formed is heat-treated. A lens having a desired shape is formed by applying rheology accompanying melting. In such a manufacturing method, since a lens is formed using melting of glass in a heat treatment process, it is necessary to provide a gap between at least the lens. This is because when the adjacent lens patterns come into contact with each other, the molten glass acts in a direction that reduces the surface area of the lens shape as much as possible, so that the radius of curvature of the lens becomes large and tends to be flat.

At this time, it is conceivable that the temperature of the heat treatment is lowered to keep the viscosity at the time of melting the glass large, thereby restricting the flow of the glass between adjacent lens patterns and preventing the flattening of the lens. However, when the lens pattern is formed with two steps as in Patent Document 1, the step remains due to the restriction of the flow of glass, and it becomes difficult to obtain a desired spherical surface. Therefore, it is conceivable to prepare more photomasks with different ratios of apertures and light-shielding parts and increase the number of exposures to increase the number of steps of the lens pattern before heat treatment, but it can be closer to a spherical surface, but the number of processes increases. It is not preferable from the viewpoint of productivity.
JP-A-8-166502

  It has been found through experiments conducted by the present inventors that the microlens array manufacturing method disclosed in Patent Document 1 has further problems. This problem will be described with reference to FIG. As shown in FIG. 14A, first, a photosensitive glass paste was formed on a glass substrate 1, and a lens pattern 2 was formed by exposure and development. The lens patterns 2 are independent from each other, and the thickness between adjacent lenses is zero. Next, heat treatment was performed on the formed lens pattern 2. By the heat treatment, the photosensitive resin was decomposed at about 400 ° C. and baked at about 600 ° C. As shown in FIG. 14B, the microlenses 3 formed in this way were completely separated and adjacent to each other. FIG. 15 shows a photograph of a regular hexagonal microlens after firing, and FIG. 16 shows a three-dimensional shape of the microlens. It can be seen from these photographs and three-dimensional shape diagrams that adjacent lenses are completely separated. As shown in the enlarged view of FIG. 14 (c), the lens pattern 2 contracts in the plane direction by firing, and as a result, the vicinity of the outer edge of the lens rises upward, and as a result, the lens pattern 2 is deformed into an aspherical shape. Characteristics deteriorated. When the lens pattern 2 is formed in a cylindrical shape, as shown in FIG. 14 (d), it shrinks in the plane direction by firing, and along with this, the vicinity of the outer edge of the lens rises above the central portion and becomes concave. It became the shape of. This result also confirms that the lens shape is deformed into an aspherical shape by firing near the outer edge of the lens by firing.

  The present invention has been made to solve such problems, and it is an object of the present invention to provide a microlens array substrate having high condensing characteristics and a method of manufacturing the microlens array substrate.

  A microlens array substrate according to the present invention is a microlens array substrate including a glass substrate and a number of microlenses formed on the glass substrate, the main component of which is a glass. They are coupled by a glass material on which microlenses are formed.

  Here, the thickness δ of the coupling portion between adjacent microlenses is preferably 0.1 μm ≦ δ ≦ 200 μm. Also, let g (x) be the cross-sectional curve of an arbitrary line segment that passes through the lens center of the microlens and connects both ends of the lens, and f When (x), when the microlens is a spherical lens, the amount of spherical deviation that can be represented by the root mean square value (rms value) of the difference in the height direction between f (x) and g (x) It is desirable that it is 0.05 μm or less. Further, the surface roughness Ra of the microlens is preferably 0.05 μm or less. In particular, the expansion coefficient of the microlens and the glass substrate may be substantially the same. The glass substrate in a preferred embodiment is a transparent substrate on which electrodes are formed in a liquid crystal display device.

  A method for producing a microlens array substrate according to the present invention is a method for producing a microlens array substrate comprising a glass substrate and a number of microlenses formed on the glass substrate, the main component of which is glass. Forming a lens forming layer on which a plurality of microlens shapes are formed on a glass substrate; and firing the lens forming layer to form a microlens coupled between adjacent microlenses. It is a thing.

  Here, the forming step of the lens forming layer includes a step of applying a photosensitive glass paste made of glass powder and a photosensitive resin on the glass substrate, and exposing the photosensitive glass paste after the application through a gray scale. And a step of forming a microlens shape having a coupling portion by development. The thickness δ of the coupling portion between adjacent microlenses is preferably 0.1 μm ≦ δ ≦ 200 μm.

  According to the present invention, it is possible to provide a microlens array substrate having a high light condensing characteristic and a method for manufacturing the microlens array substrate.

  Hereinafter, embodiments to which the present invention can be applied will be described. The following description is to describe the embodiment of the present invention, and the present invention is not limited to the following embodiment. For the sake of clarity, the following description is omitted and simplified as appropriate. Moreover, those skilled in the art can easily change, add, and convert each element of the following embodiments within the scope of the present invention. The microlens referred to in this specification is a concept including not only a convex or concave normal lens but also a cylindrical lens, a Fresnel lens, and a prism, and the microlens array refers to an aggregate of these. Furthermore, the microlens array substrate refers to a substrate on which a microlens array is formed.

Embodiment 1 of the Invention
A method for manufacturing the microlens array substrate according to the first embodiment of the present invention will be described. The manufacturing process of the microlens array substrate in the embodiment of the present invention includes a step of drawing a mask pattern on a dry plate using laser drawing to create a master gray scale mask, and an emulsion plate is exposed through the master gray scale mask. And a step of forming a mother gray scale mask and a step of exposing a photosensitive glass paste applied on a transparent substrate through the mother gray scale mask to form a microlens array. It is possible to form a microlens array using only a master gray scale mask, but using a mother gray scale mask makes it possible to obtain a large area and a large number of pieces. The present invention has a feature in a process of forming a microlens array by exposing a photosensitive glass paste applied on a transparent substrate through a mother gray scale mask, and will be described in detail below with reference to FIG.

  First, as shown in FIG. 1A, a glass transparent substrate 102 was prepared. Next, as shown in FIG. 1B, a lens forming layer 21 was formed by applying a photosensitive glass paste and forming a film over the entire area of one side of the transparent substrate 102. Application methods include spin coating and slit coating.

  The photosensitive glass paste contains glass powder (glass powder) and a photosensitive resin (resist) as main components. In order to prepare a photosensitive glass paste, first, a glass block is pulverized and made into fine particles of 10 μm or less. Thereafter, silane treatment is performed, the glass powder and the photosensitive resin are kneaded, and the glass powder is dispersed in the photosensitive resin. Thereby, a photosensitive glass paste can be prepared.

  The photosensitive resin is preferably an ultraviolet curable resin. It is preferable that the photosensitive resin can be developed with an organic solvent, an alkaline solution, or water. The ultraviolet curable resin preferably contains at least an acrylic copolymer having a carboxyl group and an ethylenically unsaturated group in the side chain and a photoreactive compound. An acrylic copolymer having a carboxyl group and an ethylenically unsaturated group in the side chain is a polymer binder component, and an acrylic copolymer formed by copolymerizing an unsaturated carboxylic acid and an ethylenically unsaturated compound is ethylene. It can be produced by adding an unsaturated group to the side chain.

  Examples of the unsaturated carboxylic acid include acrylic acid, methacrylic acid, itaconic acid, crotonic acid, and acid anhydrides thereof. Examples of the ethylenically unsaturated compound include methyl acrylate, methyl methacrylate, and ethyl acrylate. Examples of side chain ethylenically unsaturated groups include vinyl, allyl, and acrylic groups.

  Examples of the ethylenically unsaturated compound having a glycidyl group include glycidyl acrylate, glycidyl methacrylate, and allyl glycidyl ether. In the photosensitive resin contained in the photosensitive glass paste, a photosensitive polymer or a non-photosensitive polymer other than the above acrylic copolymer may be used in combination as a polymer binder component.

  Photopolymers include photo-insolubilized types and photo-solubilized types. As photo-insolubilized types, suitable polymers containing functional monomers or oligomers having one or more unsaturated groups per molecule are used. It is obtained by mixing photosensitive compounds such as aromatic diazo compounds, aromatic azide compounds, and organic halogen compounds with appropriate polymer binders, or by pendating photosensitive groups on existing polymers. Examples include photosensitive polymers or modified polymers thereof, and so-called diazo resins such as condensates of diazo amines and formaldehyde. In addition, as a light solubilizing type, a complex of an inorganic salt of a diazo compound or an organic acid, a mixture of a quinonediazide or the like with an appropriate polymer binder, a quinonediazo combined with an appropriate polymer binder, such as phenol or novolak Examples thereof include naphthoquinone-1,2-diazide-5-sulfonic acid ester of resin.

  Examples of the non-photosensitive polymer include polyvinyl alcohol, polyvinyl butyral, methacrylic acid ester polymer, acrylic acid ester polymer, acrylic acid ester-methacrylic acid ester copolymer, and α-methylstyrene polymer.

  As the photoreactive compound, a monomer or oligomer containing a carbon-carbon unsaturated bond having a known photoreactivity can be used. For example, photoreactive compounds include allyl acrylate, benzyl acrylate, butoxyethyl acrylate, butoxytriethylene glycol acrylate, and the like. Typical examples of oligomers include polyester acrylate, urethane acrylate, and epoxy acrylate.

  Examples of the photopolymerization initiator used for the ultraviolet curable resin include benzophenone, methyl o-benzoylbenzoate, 4,4-bis (dimethylamine) benzophenone, 4,4-bis (diethylamino) benzophenone, 4,4. -Combinations of reducing agents such as dichlorobenzophenone.

  In the embodiment of the present invention, the burning temperature of the photosensitive resin is about 500 ° C., which is lower than the softening temperature of the glass powder, 600 ° C. In the example shown in FIG. 1, a so-called negative photoresist in which the photosensitive portion is cured is used as the photosensitive resin. Compared to a positive photoresist, a negative photoresist is more suitable for forming a polygonal lens. When a positive photoresist is used, there is a problem that when the reflow is performed at a high temperature, the corners of the polygonal shape are rounded and the polygonal shape cannot be maintained. However, a positive photoresist may be used in the case where it is not necessary to be highly accurate even in the case of a polygonal lens or in the case of a circular lens.

As the glass powder, non-alkali glass made by SCHOTT was used. This material has α = 37 × 10 ⁻⁷ , n = 1.53, and a center particle diameter D50 = 0.4 μm. The volume percentage of glass contained in the photosensitive glass paste is preferably 30 to 50%. In this example, it was 40%. Further, it is desirable that the glass powder and the photosensitive resin have substantially the same refractive index.

  Next, as shown in FIG. 1C, a gray scale mask 30 was placed on the opposite side of the surface on which the lens forming layer 21 was formed, and exposed. The exposure light irradiated from the gray scale mask 30 side is intensity-modulated by the lens forming area of the gray scale mask 30. More specifically, intensity modulation is applied so that the exposure intensity decreases concentrically with the central portion of the lens forming area as a maximum. The lens forming layer 21 is cured into a lens shape by the exposure light subjected to intensity modulation by the lens forming region of the gray scale mask 30. As shown in FIG. 1D, after the exposure of the lens forming layer 21 is completed, the uncured portion is removed by developing the lens forming layer 21.

  FIG. 2 shows a correspondence relationship between the transmittance distribution of the gray scale mask 30 and a cross section after the lens forming layer 21 is exposed and developed using the gray scale mask 30. As shown in FIG. 2, the transmittance distribution of the gray scale mask 30 corresponds to the curvature of the lens of the lens forming layer 21. As shown in the lower part of FIGS. 2A and 2B, adjacent lenses are connected by a coupling portion 211. The coupled portion 211 shown in FIG. 2A is a sharp valley, and the lens forming layer 21 having a constant thickness exists between the bottom of the valley and the transparent substrate 102. In addition, a substantially flat portion having a predetermined width is formed on the surface of the coupling portion 211 shown in FIG. In order to obtain such a shape, the gray scale mask 30 has a predetermined non-zero transmittance so that predetermined exposure light is irradiated onto the photosensitive glass paste in a portion corresponding to the coupled portion 211. ing.

  Further, heat treatment (firing) was performed at a temperature equal to or higher than the softening temperature of the glass to form a microlens 202 (FIG. 1 (e)). FIG. 3 shows a temperature change in the heat treatment process. As shown in the figure, the temperature increased in accordance with the heat treatment, the photosensitive resin decomposed at about 400 ° C., and the carbides volatilized at about 500 ° C. Furthermore, the glass melted at a temperature above the glass softening point.

  In the microlens array 200 according to the present embodiment, adjacent lenses are coupled by a glass material that forms the lens. The thickness δ (thickness after firing) from the upper surface of the transparent substrate 102 at the boundary between the lenses coupled with the glass material is preferably 0.1 μm ≦ δ ≦ 200 μm. A more preferable range is 0.5 μm ≦ δ ≦ 50 μm, and a more preferable range is 1 μm ≦ δ ≦ 10 μm. In the present embodiment, δ is 1.0 μm. When δ was larger than 200 μm, it was confirmed that cracking was caused by the stress of the glass film at the boundary during firing. Here, it is desirable that the expansion coefficients of the microlens array 200 and the transparent substrate 102 are substantially the same. Specifically, when the expansion coefficient of the transparent substrate 102 is α1 and the expansion coefficient of the microlens array 200 is α2, the absolute value of (α1−α2) / α1 is preferably 0.5 or less. That is, it is desirable that the ratio of the difference between α1 and α2 to α1 is 50% or less. By making the expansion coefficients of the two substantially the same, it is possible to prevent the microlens array 200 from being cracked and broken due to stress generated by the heat treatment.

In the method for manufacturing a microlens array substrate according to the present invention, the glass was softened and shrunk by the heat treatment, but the condensing characteristics of the lens were not deteriorated. The reason for this will be described with reference to FIG. FIG. 4 is a partially enlarged cross-sectional view simultaneously showing a state in which exposure / development is completed in the lens forming layer 21 (a state before firing) and a state in which the microlens 202 is formed after firing. As shown in the figure, it can be seen that the film shrinks in the height direction (optical axis direction) by firing. However, although a force F1 that contracts in the plane direction of the microlens array (the lens arrangement direction) is generated, the adjacent lenses are coupled in the coupling unit 2021, and thus are not separated between the adjacent lenses. The force F1 is alleviated by the reaction force F2 generated on the transparent substrate 102. Therefore, the lens does not rise upward (in the direction away from the transparent substrate 102) at the outer peripheral portion of the lens, and the lens contracts in the height direction almost uniformly, so that it is analyzed that the light condensing characteristic of the lens does not deteriorate.
FIG. 5 shows a photograph of the fired microlens manufactured by the manufacturing method according to the present invention, and FIG. 6 shows a three-dimensional shape diagram of the microlens. From these photographs and three-dimensional shape diagrams, it can be seen that the lenses are not separated and the lens shape is maintained.

  Next, the relationship between the firing temperature, the surface roughness Ra, and the transmittance of the lens forming layer 21 will be described. FIG. 7 is a table showing the relationship between the three. In the experiment, a microlens array was formed by changing the firing temperature from 550 ° C. to 600 ° C., and the surface roughness Ra and transmittance of the formed microlens array were measured. The roughness was measured using a laser microscope (non-contact three-dimensional measuring device: NH3 manufactured by Mitaka Kogyo Co., Ltd.) under the conditions of a cutoff of 80 μm and a measurement length of 480 μm. Moreover, the transmittance | permeability was measured using the spectroscope made from Shimadzu Corporation, and calculated | required the average value in wavelength 400-800 nm.

  FIG. 8 is a graph in which the relationship between the firing temperature and the surface roughness is plotted based on the data shown in the table of FIG. 7, and FIG. 9 is a graph in which the relationship between the surface roughness and the transmittance is similarly plotted. In the microlens array mounted on the liquid crystal display device, the transmittance is preferably 83% or more, and more preferably 90% or more. In order for the transmittance to be 83% or more, as shown in FIG. 9, the surface roughness Ra needs to be 0.05 μm or less. Similarly, for the transmittance to be 90% or more, the surface roughness Ra needs to be 0.02 μm or less. And as FIG. 8 shows, in order for surface roughness Ra to be 0.05 micrometer or less, it is necessary to be a calcination temperature of about 560 degreeC or more, and since surface roughness Ra is 0.02 micrometer or less. Is required to have a firing temperature of about 565 ° C. or higher.

Furthermore, as another guideline for evaluating the stability of the lens curvature of the microlens 202, there is the sphericity of the lens. The rms (root mean square) value for evaluating the sphericity of the lens can be expressed as the following equation (1).
FIG. 10 is a graph obtained by measuring the sphericity of the microlens. The sphericity of a lens is an ideal spherical surface obtained by fitting the curve of an arbitrary line segment passing through the center of the microlens and connecting both ends of the lens to g (x) and fitting to the g (x) by the least square method. When f (g) is the curve, the mean square value (rms value) of the difference in the height direction between f (x) and g (x) was evaluated as the amount of spherical deviation. The smaller this value is, the closer the lens curvature is to a true sphere and the more stable the curvature. FIG. 11 is a table (FIG. 11A) and a graph (FIG. 11B) showing the relationship between the amount of spherical deviation of the microlens and the wavefront aberration in the case of a spherical lens. According to the Marshall limit value, if the wavefront aberration is 0.07λ rms or less, it generally has a lens function. Therefore, as shown in FIG. 11, the spherical lens has a spherical deviation of 0.05 μm or less. Good. That is, the spherical deviation amount of the spherical lens may be 0 or more and 0.05 μm or less.

Embodiment 2 of the Invention
In the first embodiment of the invention, a negative photoresist is used as the photosensitive resin in the photosensitive glass paste. However, in the second embodiment, the photosensitive portion is decomposed and the solubility in a solvent is improved. Photoresist is used.

  A method of manufacturing the microlens array substrate according to the second embodiment will be described with reference to FIG. First, as shown in FIG. 12A, a glass transparent substrate 102 was prepared. Next, as shown in FIG. 12B, a lens forming layer 21 was formed by applying and forming a photosensitive glass paste over the entire area of one side of the transparent substrate 102.

  Next, as shown in FIG. 12C, a gray scale mask 30 was placed above the lens forming layer 21 and exposed. The exposure light irradiated from the gray scale mask 30 side is intensity-modulated by the lens forming area of the gray scale mask 30. More specifically, intensity modulation is applied so that the exposure intensity increases concentrically with the central portion of the lens forming area as a minimum. Due to the exposure light intensity-modulated by the lens forming area of the gray scale mask 30, the lens forming layer 21 is decomposed by a developer other than the lens shape.

  As shown in FIG. 12D, after the exposure of the lens forming layer 21 was completed, the uncured portion was removed by developing the lens forming layer 21. In the lens forming layer 21, a coupling portion is formed between adjacent lens shapes. Further, heat treatment (firing) was performed at a temperature equal to or higher than the softening temperature of the glass to form the microlens 202 (FIG. 12E). In the microlens array according to the present embodiment, adjacent lenses are connected by a glass material that forms the lens.

  In the method for manufacturing a microlens array substrate according to the present invention, the glass was softened and shrunk by the heat treatment, but the condensing characteristics of the lens were not deteriorated.

Application example of microlens array substrate.
The microlens array substrate according to the embodiment of the present invention can be mounted on a liquid crystal display device. FIG. 13 is a cross-sectional view of a liquid crystal display device on which a microlens array substrate is mounted. This liquid crystal display device is a so-called transflective liquid crystal display device. In FIG. 13, the liquid crystal display device includes a liquid crystal panel 100 and a microlens array 200. In the liquid crystal panel 100, a liquid crystal layer 103 is sandwiched between two transparent substrates 101 and 102.

  A transparent electrode 106 and an alignment film 107 are sequentially stacked between the color filter layer 104 and the liquid crystal layer 103. A TFT element 108 is formed on the transparent substrate 102 disposed on the back side of the liquid crystal panel 100, and a transparent electrode 106 and an alignment film 107 are laminated. A pixel electrode 161 and a wiring 162 are formed on the transparent electrode 106 on the TFT element 108 side, and the pixel electrode 161 has an opening 161a and a reflection portion 161b. The opening 161a serves as a path for light incident on the liquid crystal panel 100 from the transparent substrate 102 side. The reflector 161b serves as a reflector that reflects light incident from the transparent substrate 101 side.

  A microlens array 200 is provided on the back side of the transparent substrate 102. The microlens array 200 has a rim 201 and a microlens 202. Since the microlens array 200 condenses the light from the backlight on the opening 161a, the light use efficiency can be increased and the luminance can be increased. For example, in the case of the transflective type, the light use efficiency could be improved about 3 times. In the case of the transmissive type, the light utilization efficiency could be improved about twice. The polarizing plate 109 is an optical member having a function of transmitting only a specific polarization component with respect to incident light, and is attached to both side surfaces of the two transparent substrates 101 and 102. The spacers 110 are resin particles that control the height of the liquid crystal layer 103 between the transparent substrates 101 and 102, and a plurality of spacers 110 are scattered over the entire range between the transparent substrates 101 and 102.

  The microlens array substrate according to the embodiment of the present invention is not limited to a liquid crystal display device, but can be used in other applications.

It is a figure which shows the manufacturing method of the micro lens array board | substrate concerning this invention. It is a figure which shows the relationship between the distribution of the transmittance | permeability of a gray mask, and the structure of the lens formation layer after exposure and image development. It is a graph which shows the temperature change in a heat treatment process. It is sectional drawing which shows the structural change by heat processing. It is a photograph of the micro lens array formed by the manufacturing method of the present invention. It is a three-dimensional shape diagram of a microlens array formed by the manufacturing method of the present invention. It is a table | surface which shows the relationship between baking temperature, surface roughness Ra, and the transmittance | permeability. It is a graph which shows the relationship between surface roughness Ra and baking temperature. It is a graph which shows the relationship between the transmittance | permeability and surface roughness Ra. It is a graph which shows the example of a measurement of the sphericity of a micro lens. It is the table | surface and graph which show the relationship between the spherical displacement amount of a microlens, and a wavefront aberration. It is a figure which shows the manufacturing method of the micro lens array board | substrate concerning this invention. It is sectional drawing of the liquid crystal display device concerning this invention. It is a figure for demonstrating the conventional problem. It is a photograph of the micro lens array formed by the conventional manufacturing method. It is a three-dimensional shape diagram of a microlens array formed by a conventional manufacturing method.

Explanation of symbols

21 Lens forming layer 102 Transparent substrate 202 Micro lens 211 Coupled portion

Claims (9)

A microlens array substrate comprising a glass substrate and a number of microlenses formed on the glass substrate, the main component of which is glass,
Adjacent microlenses are microlens array substrates that are connected by a glass material on which the microlenses are formed.   2. The microlens array substrate according to claim 1, wherein the thickness δ of the coupling portion between adjacent microlenses is 0.1 μm ≦ δ ≦ 200 μm.   A curve of a cross section of an arbitrary line segment passing through the lens center of the microlens and connecting both ends of the lens is defined as g (x), and a curve of an ideal spherical surface fitted to the g (x) by the least square method is represented by f (x ), The amount of spherical displacement that can be represented by the mean square value (rms value) of the difference in the height direction between f (x) and g (x) is zero when the microlens is a spherical lens. 2. The microlens array substrate according to claim 1, wherein the microlens array substrate is 05 μm or less.   2. The microlens array substrate according to claim 1, wherein the surface roughness Ra of the microlens is 0.05 [mu] m or less.   2. The microlens array substrate according to claim 1, wherein the microlens and the glass substrate have substantially the same expansion coefficient.   2. The microlens array substrate according to claim 1, wherein the glass substrate is a transparent substrate on which electrodes are formed in a liquid crystal display device. A method for producing a microlens array substrate comprising a glass substrate and a number of microlenses formed on the glass substrate, the main component of which is glass,
Forming a lens forming layer in which a number of microlens shapes are formed on the glass substrate;
Forming a microlens coupled between adjacent microlenses by firing the lens forming layer. The step of forming the lens forming layer includes:
Applying a photosensitive glass paste made of glass powder and photosensitive resin on the glass substrate;
8. The microlens array substrate according to claim 7, further comprising a step of forming a microlens shape having a coupling portion by exposing and developing the photosensitive glass paste after application through a gray scale. Manufacturing method.   8. The method of manufacturing a microlens array substrate according to claim 7, wherein the thickness δ of the coupling portion between adjacent microlenses satisfies 0.1 μm ≦ δ ≦ 200 μm.