JP2011059156A - Method of manufacturing microlens array and microlens array manufactured by the method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a microlens array including a glass-made microlens having excellent condensing performance for achieving display of a high-density image even in constant high-temperature operating environment. <P>SOLUTION: The method of manufacturing a microlens array includes: a recess forming step of forming a plurality of recesses corresponding to the microlens on one face of a substrate surface; a lens base material-filling step of filling the recesses of the recessed substrate where the recesses are formed with a paste-like lens base material with which powder of lens material is mainly mixed; and a baking step of vitrifying the filling lens base material. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a microlens array manufacturing method and a microlens array manufactured by the method.

A projection display device that projects an image on a screen is known.
In such a projection display device, a liquid crystal panel (liquid crystal light shutter) is mainly used for image formation. In this liquid crystal panel, for example, a liquid crystal driving substrate (TFT substrate) having a thin film transistor (TFT) for controlling each pixel and a pixel electrode, and a counter substrate for a liquid crystal panel having a black matrix, a common electrode, etc. It becomes the structure joined via. In the liquid crystal panel having such a configuration (TFT liquid crystal panel), since the black matrix is formed in a portion other than the portion of the counter substrate for the liquid crystal panel, the region of light transmitted through the liquid crystal panel is limited. For this reason, the light transmittance decreases.

  In order to increase the light transmittance, a counter substrate for a liquid crystal panel is known in which a large number of microlenses are provided at positions corresponding to each pixel. Thereby, the light which permeate | transmits the opposing board | substrate for liquid crystal panels is condensed by the opening formed in the black matrix, and the transmittance | permeability of light increases. As a method for forming such a microlens, for example, an uncured photocurable resin is supplied to a substrate with recesses having a plurality of recesses for forming microlenses, and a smooth transparent substrate (cover glass) is joined. A so-called 2P method is known in which a resin is cured by pressing and intimate contact (see, for example, Patent Document 1).

  However, in the method according to Patent Document 1, since a resin material is used for forming the microlens substrate, it is difficult to obtain a microlens substrate having sufficient durability. In particular, since the photocurable resin used in the 2P method is likely to cause deterioration of the resin material due to light having a short wavelength, sufficient light resistance may not be obtained. In addition, since the microlens substrate is formed using the three members of the resin layer composed of the photocurable resin, the cover glass, and the substrate with the recesses, distortion or the like is likely to occur due to a difference in thermal expansion coefficient. As a result, characteristics such as optical characteristics may be degraded. For example, a process such as alignment of the cover glass is necessary, and the manufacturing process is complicated. In addition, when the cover glass is polished to obtain the optimum optical path length, dirt due to polishing occurs, and therefore an excessive cleaning step is required. By performing such cleaning, the resin layer is configured. There was a possibility that the resin material to be deteriorated. As a result, the quality may be reduced, and the yield may be reduced.

  In addition, a microlens array manufacturing method using a glass material excellent in optical characteristics and durability of a microlens as a microlens material is also known (see, for example, Patent Document 2).

  However, even in the method according to Patent Document 2, since the lens base material is heated beyond the glass transition point (Tg) and pressed against the substrate recess where the microlens is formed by pressure, the substrate recess In order for the lens base material to reliably fill the shape part, the heating temperature must greatly exceed Tg. Due to the risk of damage due to pressure contact, the glass material used for the microlens is required to have a Tg lower than that of the lens substrate and to reduce the difference in linear expansion coefficient from a predetermined value. In order to satisfy this requirement, although the lens material is required to have a higher refractive index, only a minimum refractive index for fulfilling the lens function can be realized.

JP 2001-92365 A JP 2006-313279 A

  However, even with the above-described prior art, the liquid crystal panel and the like equipped in the projection display device is excellent in the light collecting performance that realizes the display of high-density images in recent years even under the always high temperature use environment. A new method for manufacturing a microlens array having a glass microlens has been desired.

  The present invention can be realized as the following forms or application examples so as to solve at least one of the above-described problems.

[Application Example 1]
The manufacturing method of the microlens array of this application example is a manufacturing method of a microlens array having a plurality of microlenses, and forming a plurality of recesses corresponding to the microlenses on one surface side of the substrate surface A lens base material filling step of filling the concave portion of the substrate with concave portions in which the concave portions are formed with a paste-like lens base material kneaded with a powder of lens material as a main material, and the filled lens And a firing step for vitrifying the substrate.

  According to the microlens array manufacturing method of this application example, a glass material having excellent durability and high refractive index can be applied to the microlens. Furthermore, since it is made paste-like, high fluidity | liquidity can be provided, Even if it is a uniform and fine recessed part in the recessed part of a board | substrate with a recessed part, filling of a lens material can be performed reliably. In the firing step, a large number of microlens arrays can be introduced, and firing can be performed by so-called batch processing. Therefore, high productivity can be realized.

[Application Example 2]
In the method for manufacturing a microlens array according to the application example described above, the lens base material is: (A) Glass main material: 45% by weight to 75% by weight (B) Binder: 1% by weight to 10% by weight of the glass main material A The following (C) Solvent: It contains the remaining amount of (A + B).

[Application Example 3]
In the method for manufacturing a microlens array according to the application example described above, the (A) glass main material has a particle diameter of 10 nm to 10 μm.

  According to the manufacturing method of the microlens array of the application example described above, it is possible to impart appropriate fluidity to the lens base material and improve the filling property of the glass material into the recesses of the substrate with recesses.

[Application Example 4]
In the microlens array manufacturing method according to the application example described above, in the lens base material filling step, the lens base material is filled by screen printing.

  According to this application example, it is possible to accurately fill the glass paste serving as the lens base material with respect to the concave portion formation position of the concave substrate. In particular, in a method of manufacturing by forming a plurality of substrates with recesses on a wafer, the lens base material can be accurately filled in the recess formation position of each substrate with recesses, and the lens is not formed on the portion where the recesses are not formed. No substrate can be supplied. Accordingly, waste is not generated in the glass paste of the lens base material, and the manufacturing cost can be reduced.

[Application Example 5]
In the microlens array manufacturing method according to the application example described above, in the lens base material filling step, the lens base material is applied to the smooth surface of a substrate having a smooth surface, and the solvent is evaporated to form a green sheet. And a pressing step of pressing and filling the green sheet into the concave portion of the substrate with concave portions.

  According to this application example, the outer surface portion of the pressed and filled green sheet is formed by transferring the smooth surface of the green sheet forming substrate, and thus has a smooth surface. Therefore, a smooth surface is maintained on the outer surface portion of the microlens even after the lens substrate (green sheet) is fired. Therefore, since post-processing by polishing such as flattening after baking and polishing is not required, the manufacturing cost can be reduced.

[Application Example 6]
In the manufacturing method of the microlens array according to the application example described above, the substrate with concave portions is quartz glass, and the glass main material A is:
Silicon oxide (a): 35 to 70% by weight
Boron oxide (b): 10 to 25% by weight
Metal oxide (c): 8 to 50% by weight
As the main component,
(A) + (b) ≧ 50% by weight
It is characterized by being.

[Application Example 7]
In the method of manufacturing a microlens array according to the application example described above, the metal oxide (c) includes germanium oxide, bismuth oxide, tin oxide, titanium oxide, lead oxide, gadolinium oxide, lanthanum oxide, strontium oxide, antimony oxide, and oxide. It contains barium, zinc oxide, aluminum oxide, phosphorus oxide, arsenic oxide alone or in combination of two or more.

  According to these application examples, a quartz glass concave substrate has a high refractive index and a small difference in absolute value of linear expansion coefficient. Even if a microlens array is used in a high temperature range, The occurrence of defects such as cracks and cracks due to the difference in thermal expansion can be suppressed.

[Application Example 8]
It is the microlens array manufactured by the above-mentioned application example.
According to this application example, it is particularly suitable for a liquid crystal panel used for a liquid crystal light valve of a projection display device that is placed in a high temperature environment for a long time.

The microlens array in 1st Embodiment is shown, (a) is a schematic plan view, (b) is a schematic sectional drawing. The flowchart which shows the manufacturing process in 1st Embodiment. The board | substrate manufacturing process with a recessed part in 1st Embodiment is shown. The lens base material filling process in 1st Embodiment is shown. The heating pattern figure of lens base material baking in a 1st embodiment. The flowchart which shows the manufacturing process in 2nd Embodiment. The lens base material filling process in 2nd Embodiment is shown. The schematic diagram of the optical system of the projection type display apparatus using this invention is shown. The schematic sectional drawing of the liquid crystal panel using this invention is shown.

Embodiments according to the present invention will be described below with reference to the drawings.
(First embodiment)
1A and 1B are schematic views of a microlens array according to an embodiment of the present invention, in which FIG. 1A is a plan view and FIG. 1B is an LL ′ cross-sectional view of FIG. In the microlens array 10, a microlens base material is fixed to a substrate 12 with a recess having a plurality of recesses 12 a corresponding to the plurality of microlenses 11 to form the microlens 11. By using a high refractive index material for the material of the microlens 11 relative to the material of the substrate 12 with recesses, the light incident from the outside Q on the substrate 12 side with recesses in FIG. It has a function of condensing in the P direction by refraction when emitted to the outside.

FIG. 2 shows a manufacturing flowchart of the present embodiment.
[Lens substrate adjustment process]
The material for the microlens 11 is adjusted. The material is adjusted to a paste by mixing a fine particle glass main material for a lens, a binder mainly composed of a resin component for connecting the glass main material, a plasticizer, and a solvent (S101). The blending ratio of each material is determined by a filling means (method) in a lens base material filling step (S103) described later. in this case,
(A) Glass main material: 45% by weight or more and 75% by weight or less (B) Binder: 1% by weight or more and 10% by weight or less of glass main material A (C) Solvent: Determined by the range of the remaining amount of (A + B). . Preferably, the glass main material is 65% by weight, the binder is 3% by weight, and the material is adjusted using the remaining amount as a solvent. If the filling method requires high fluidity, the glass main material is reduced. If the filling method does not require fluidity, the glass main material may be increased.

  The glass main material is not limited as long as it has a high refractive index with respect to the material of the substrate with recesses described below and has a small difference in absolute value of the linear expansion coefficient. For example, soda glass, crystalline glass, crown glass, potassium glass, lead glass, borosilicate glass, bismuth glass mainly composed of borosilicate glass and bismuth oxide, germanium oxide mainly composed of borosilicate glass and germanium oxide It is selected from system glass. When the material of the substrate with recesses is quartz glass, borosilicate glass, bismuth glass mainly composed of borosilicate glass and bismuth oxide, and germanium oxide glass mainly composed of borosilicate glass and germanium oxide are glass main materials. As preferred.

  Moreover, it is preferable that the particle size of a glass main material is 10 micrometers or less in order to ensure fluidity | liquidity. However, making the particle size finer is preferable in terms of product manufacturing, but from the viewpoint of manufacturing glass particles, the manufacturing cost has increased significantly, such as equipment costs and a long manufacturing process. It becomes more difficult to equalize. Therefore, it is preferable that the particle diameter is 10 nm or more from the limitation of fine particle production.

  The binder is not particularly limited as long as it is a resin component, but it must be a material that can be surely evaporated in the firing step described below, in addition to the ability to keep glass material fine particles. For example, polyvinyl butyral (PVB), cellulose resin, and the like can be suitably used.

  Examples of the solvent include low boiling point type ethanol, acetone, medium boiling point type butanol, toluene, high boiling point type isophorone, terpineol and the like. Preferably, a high boiling point type solvent or the like may be used alone or as a mixture of a plurality of types for the paste material. As the solvent, a suitable material and combination are selected from the allowable volatilization time depending on the filling method in the lens base material filling step described later. In this embodiment, it is preferable to use a high boiling point type solvent.

  Although the apparatus which mixes the above-mentioned material is not limited, It is preferable to use a three roll mill apparatus and a ball mill apparatus as a method of obtaining a mixture uniformly and in a short time. When using a ball mill device, glass balls are not used as mill balls. That is, since the vitreous scraped from the mill balls is mixed as an impurity, it is difficult to maintain the quality. For example, it is preferable to put a hard material such as zirconia ceramics into a ball mill apparatus as a mill ball.

[Recessed substrate manufacturing process]
In addition to the lens base material adjusting step (S101) described above, a substrate with a recess is prepared (substrate manufacturing step with a recess: S102). The substrate with the recesses is manufactured by the method shown in FIG.

<Mask forming film forming step>
First, a substrate with a recess is manufactured. FIG. 3 shows an example of a method for manufacturing a substrate with recesses. As shown in FIG. 3A, first, a glass substrate 20 having a uniform thickness and no scratches and a cleaned surface is prepared, and a mask forming film 21 is formed on the surface of the glass substrate 20. The mask forming film 21 functions as a mask by forming an opening (initial hole) in a later step. As will be described later, the mask forming film 21 is formed with an initial hole 22 by laser irradiation, and then a recess is formed in the glass substrate 20 from the initial hole 22 by etching. Accordingly, it is preferable that the mask forming film 21 has resistance to etching. That is, it is preferable that the etching rate of the mask forming film 21 is configured to be smaller than that of the glass substrate 20.

  From this, the material of the mask forming film 21 is, for example, a metal such as Cr, Au, Ni, or Pt, or an alloy containing two or more selected from these, or an oxide such as Cr, Au, Ni, or Pt ( Metal oxide), silicon, resin and the like. Moreover, it is good also as a several laminated structure which consists of a different material like Cu and Au or oxide Cr and Cr. A method for forming the mask forming film 21 is not particularly limited, but, for example, an evaporation method, a sputtering method, a CVD method, or the like is selected depending on the film material. The film thickness is also set to about 0.01 to 0.2 μm, and a suitable thickness is set according to the initial hole formation conditions and the etching conditions.

<Initial hole forming step>
After the mask forming film 21 is formed on the surface of the glass substrate 20, as shown in FIG. 3B, the mask forming film 21 corresponds to the initial hole 22 that becomes a mask opening in the later-described etching. It is formed at the microlens formation position. Thereby, the mask 23 having a predetermined opening pattern is obtained.

  As a method for forming the initial hole 22, laser light irradiation, etching treatment, blast treatment such as sand blasting, or the like is applied. In the present embodiment, high positional accuracy can be maintained, and the interval between adjacent initial holes 22 can be accurately controlled. Therefore, laser beam irradiation is applied to the formation of the initial holes 22.

<Etching process>
Next, as shown in FIG. 3C, a recess 24 is formed in the glass substrate 20 by etching through the initial hole 22 formed in the mask 23. The etching method is not particularly limited, and examples include wet etching and dry etching. In this embodiment, the recess 24 is formed by wet etching. Although not limited as an etching solution, in this embodiment, a hydrofluoric acid-based etching solution containing hydrofluoric acid (hydrogen fluoride) is used. By using a hydrofluoric acid-based etchant, the glass substrate 20 can be etched more selectively, and the recesses 24 can be suitably formed.

  By etching the glass substrate 20 covered with the mask 23 in which the initial holes 22 are formed, the glass substrate 20 has the initial holes 22 formed in the mask 23, as shown in FIG. That is, the recess 24 is formed by etching with an etching solution from a portion where the mask material does not exist. The glass substrate 20 is gradually etched by controlling the etching time and the like, so that a recess 24 having a predetermined depth shown in FIG.

<Mask removal process>
Next, the mask 23 is removed by etching or the like, and as shown in FIG. 3E, a substrate 25 with recesses having a large number of recesses 24 is obtained.

[Lens substrate filling process]
In FIG. 4, the lens base material prepared in the lens base material adjustment step (S101) is filled into the concave portion 24 of the concave substrate 25 prepared in the concave substrate manufacturing step (S102) (S103). A process is shown. FIG. 4A is a plane viewed from the side where the recess 24 is formed, and a part of the recess shape is drawn and the others are omitted. FIG. 4B shows a schematic cross-sectional view along AA ′ of FIG.

  If the substrate with recesses 25 manufactured in the substrate manufacturing process with recesses (S102) is necessary, preparations such as washing and drying are made. Next, the lens base material is filled into the concave portions 24 of the substrate with concave portions 25 by screen printing. First, the screen printing plate 30 is placed. At this time, a mesh pattern 30 a is formed on the screen printing plate 30 according to the filling amount of the lens base material 31 at the position corresponding to the recess 24. This mesh pattern is determined by the fluidity of the lens base material 31 and the depth size of the recess 24 of the substrate 25 with recesses. As the simplest pattern, the entire surface of the lens formation range is imprinted. A so-called solid pattern may be formed. Further, the printing apparatus is not limited.

  The lens base material 31 is put into the placed screen printing plate 30, and the lens base material 31 is slid by the squeegee 32 so that the lens base material 31 is filled in the concave portion 24 of the substrate 25 with the concave portion. As a result, the pre-firing microlens array 33 is filled with a lens base material as shown.

[Baking process]
The pre-firing microlens array 33 is dried for about 30 minutes using an atmosphere drying furnace at 100 ° C. to 200 ° C. The dried pre-fired microlens array 33 is fired by a heating pattern shown in FIG. 5 by a heating device such as an electric furnace (S104). Sintering temperature T _o is the temperature above the glass softening point of the glass main material in the lens base material, the preheating temperature T _b evaporating the binder and solvent is carried out at a temperature lower than the glass softening point. T _o and the baking time, T _b and pre-heating time is optimally determined by the lens base material component. T _b at a temperature of 400 ° C. to 500 ° C. is performed for the purpose of removing the binder is carried out for about 30 minutes to 60 minutes. T _o is is determined by the glass main members, when the lens substrate was quartz glass, it is preferred for the lens substrate is 1000 ° C. or less as a temperature range that does not give a thermal stress. More preferably, it is in the range of 850 ° C. to 950 ° C., and the firing time is 30 minutes to 60 minutes. The heating device is not limited to an electric furnace, but must be a device that does not generate impurities such as active gas and soot in order to eliminate the influence on the lens substrate.

  The microlens array 10 is completed by firing in the firing step (S104). Note that, after the firing step (S104), steps such as “planar polishing” and “outer shape dicing (cutting)” may be performed if necessary. As the planar polishing, polishing polishing may be performed when a defect is found on the outer surface of the microlens, such as predetermined specularity, flatness, and scratches. In addition, since the outer shape dicing is manufactured in a wafer form until the firing step (S104) in a manufacturing line for manufacturing a plurality of microlens arrays 10 using a wafer, there is a process of cutting into individual microlens arrays 10. Necessary. This is called outer shape dicing. In addition, if an area other than the microlens formation range of the microlens array 10 is unnecessary, the unnecessary portion is generally deleted by dicing.

(Second Embodiment)
FIG. 6 shows a flowchart of the second embodiment. Since the lens base material adjusting step (S201) and the concave substrate manufacturing step (S203) in the present embodiment are the same as the lens base material adjusting step (S101) and the concave substrate manufacturing step (S102) in the first embodiment, The description below is omitted.

[Lens substrate sheet manufacturing process]
As shown in FIG. 7 (a), the smooth surface of the film 50 in which at least one of the surfaces of the paste-like lens substrate prepared and adjusted in the lens substrate adjusting step (S201) is a smooth surface. A paste-like lens substrate 51 is applied on the top with a uniform thickness. In the present embodiment, a film 50 is used, a PET material is used as a base material, and a film on which SiO ₂ having a peeling action is formed on the surface can be suitably used. Moreover, it is a board | substrate which has a smooth mirror surface at least 1 surface, Comprising: If the surface gave the peeling process, it can be used conveniently. For example, a metal plate such as a stainless steel plate, a copper plate, an aluminum plate, a resin substrate, a glass substrate, etc., in which a fluoride film having a peeling action on the substrate surface is formed by CVD or the like, can be suitably implemented. .

  After the lens substrate 51 is applied, the solvent component is removed by natural drying or in a thermostatic bath to obtain a sheet-like solid. A so-called green sheet is formed. The green sheet has a certain level of strength as a solid substance, is not easily deformed or dents during handling, and has a high handling property during the manufacturing process. In addition, it is a highly effective manufacturing method in that it can be prepared and stored (stored) in advance, and it is not necessary to adjust the lens base material each time so that it can flexibly cope with the production volume of mass production. .

[Lens substrate filling process]
As shown in FIG. 7 (b), the lens substrate 51 (green sheet) prepared in the lens substrate adjustment step (S201) described above is similarly manufactured in advance in the substrate manufacturing step (S203) with a recess. 25 on the concave portion 24 side. At this time, the film 50 may be placed in either form affixed to the film 50 or peeled off.

  Next, as shown in FIG. 7C, the lens base 51 is pressed in the direction of the arrow by a pressing device 52 of a pressing device (pressing machine) (not shown), and the lens base 51 is placed in the recess 24 of the substrate 25 with recesses. Fill (S204). At this time, by applying heat to the lens substrate 51, the fluidity of the substrate is increased and the lens substrate 51 is easily filled, so that the concave portion 24 can be reliably filled with the lens substrate 51.

[Baking process]
Through the above-described steps, as shown in FIG. 7D, the pre-firing microlens array 33 is completed, the firing step (S205) is executed, and the microlens array 10 is completed.

(First embodiment)
A substrate with concave portions for microlenses having a plurality of concave portions was manufactured as follows, and a microlens substrate was manufactured using the substrate with concave portions for microlenses.
[Process for forming substrate with recesses]
First, a quartz glass substrate (glass transition point: 1060 ° C., refractive index: 1.46) having a thickness of 2 mm was prepared as a glass substrate. This quartz glass substrate was cleaned by immersing it in a cleaning solution (80% sulfuric acid + 20% hydrogen peroxide solution) heated to 85 ° C. to clean the surface.

  Next, a Cr film having a thickness of 0.03 μm was formed on the quartz glass substrate by sputtering. That is, a Cr film mask and a back surface protective film were formed on the surface of the quartz glass substrate. Next, laser processing was performed on the mask to form a large number of initial holes (see FIG. 3B).

  Laser processing was performed using a YAG laser under conditions of an energy intensity of 1 mW, a beam diameter of 3 μm, and an irradiation time of 60 × 10 −9 seconds. The average diameter of the formed initial holes was 5 μm. Next, the quartz glass substrate was wet etched to form a large number of recesses on the quartz glass substrate (see FIG. 3D). The etching time for this wet etching was set to 72 minutes, and a hydrofluoric acid-based etching solution was used as the etching solution.

  Next, dry etching with CF gas was performed to remove the mask and the back surface protective layer. As a result, a substrate with recesses in which a large number of recesses were regularly arranged on the quartz glass substrate was obtained. In addition, the average diameter of the formed recessed part was 15 micrometers, and the curvature radius was 7.5 micrometers. Moreover, the space | interval between the recessed parts for adjacent microlenses (average distance between centers of recessed parts) was 15 micrometers.

[Lens substrate adjustment process]
Next, a glass material as a lens material is adjusted. In this embodiment, the lens material is adjusted with the following composition, but the present invention is not particularly limited thereto.
A) Glass main material: Glass blending ratio (% by weight)
Silicon oxide (SiO ₂ ): 68.0%
Boron oxide (B ₂ O ₃ ): 22.0%
Sodium oxide, potassium oxide: 0.5%
Bismuth oxide: 9.5%
B) Binder PVB (polyvinyl butyral): 5% by weight of the main glass material
C) Solvent Ethanol: 0.2 cc / g based on the weight of the main material
Turpineol: 0.5cc / g relative to the weight of the main material

  The above materials were put in a resin bottle with a lid together with zirconia balls (diameter: Φ4 mm) about 3 times the weight of the glass main material, and mixed in a ball mill apparatus for a certain time to produce a glass paste.

[Lens substrate filling process]
The glass paste was applied by a screen printing method to the recessed portion forming portion of the substrate with recessed portions, which was prepared in advance from the adjusted and mixed glass paste. The screen plate used for screen printing has a solid pattern of mesh # 250, and the screen printing conditions are such that the glass paste becomes thicker by about 10 μm from the upper surface of the substrate with recesses after firing, and the work gap, printing pressure, etc. Adjustments were made and applied.

  The applied pre-fired microlens array was dried in an atmosphere drying furnace (atmosphere) at about 120 ° C. for about 30 minutes. As a result, the glass paste was completely solidified. Next, the glass substrate is subjected to main firing in an electric furnace, and the operation is shifted to vitrification of the glass material as the lens material. The electric furnace at this time was a muffle type electric furnace. The temperature rising sequence in the electric furnace is a sequence as shown in FIG. 5. The temperature rising 1 is raised from room temperature to 500 ° C. at a rate of 5 ° C./min, and the temperature is kept at 500 ° C. for about 1 hour. did. Next, the temperature was raised to about 850 ° C. at a rate of 10 ° C. per minute. This was maintained for about 30 minutes at this temperature and fired. The glass material melted and completely vitrified and became transparent. Then, although it naturally cooled (slow cooling) in the furnace, it can also be taken out and cooled.

The temperature sequence is for determining the glass material and a binder material, but are not limited to, set to about plus 30 to 50 ° C., particularly for T _b degreasing temperature of the binder, T _o is It sets to plus 50-100 degreeC with respect to the glass softening point temperature which is a glass material. The softening point temperature of the glass material used in this example was about 780 ° C.

  Next, in order to use this glass substrate with a lens as a counter substrate of a liquid crystal panel, the lens surface was flattened by polishing. As a result, a surface having an average surface roughness Ra = 100 nm or less was formed, and a microlens array was completed. The abrasive used at this time mainly used cerium oxide.

  The microlens array thus obtained was subjected to necessary steps as a counter substrate of the liquid crystal panel, and the TFT substrate and the liquid crystal were combined to assemble as a panel.

(Second embodiment)
Since the formation process of the substrate with recesses is the same as that of the first embodiment, the description thereof is omitted here.
[Lens substrate adjustment process]
Adjust the glass material as the lens material. In this embodiment, the lens material is adjusted with the following composition, but the present invention is not particularly limited thereto.
A) Glass main material: Glass blending ratio (% by weight)
Silicon oxide (SiO ₂ ): 47.0%
Boron oxide (B ₂ O ₃ ): 15.0%
Sodium oxide, potassium oxide: 0.5%
Germanium oxide: 37.5%
B) Binder PVB (polyvinyl butyral): 5% by weight of the main glass material
C) Solvent Ethanol: 0.2 cc / g based on the weight of the main material
Turpineol: 0.5cc / g relative to the weight of the main material

[Lens substrate filling process]
A glass paste obtained by the same method as that of the first example using the above materials was filled into a substrate with a recess. The filling method was performed by the same screen printing as in the first example. The obtained pre-fired microlens array was subjected to preheating under the same conditions as in the first example, and then raised to about 950 ° C. at a rate of 10 ° C./min. This was maintained for about 30 minutes at this temperature and fired. The glass material melted and completely vitrified and became transparent. Then, although it naturally cooled (slow cooling) in the furnace, it can also be taken out and cooled. The softening point temperature of the glass material used in this example was about 870 ° C.

  The microlens array thus obtained was subjected to necessary steps as a counter substrate of the liquid crystal panel, and the TFT substrate and the liquid crystal were combined to assemble as a panel.

(Third embodiment)
Since the formation process of the substrate with recesses is the same as that of the first embodiment, the description thereof is omitted here.
[Lens substrate adjustment process]
Adjust the glass material as the lens material. In this embodiment, the lens material is adjusted with the following composition, but the present invention is not particularly limited thereto.
A) Glass main material: Glass blending ratio (% by weight)
Silicon oxide (SiO ₂ ): 48.0%
Boron oxide (B ₂ O ₃ ): 15.5%
Sodium oxide, potassium oxide: 0.5%
Bismuth oxide: 10.0%
Germanium oxide: 26.0%
B) Binder PVB (polyvinyl butyral): 5% by weight of the main glass material
C) Solvent Ethanol: 0.2 cc / g based on the weight of the main material
Turpineol: 0.5cc / g relative to the weight of the main material

[Lens substrate filling process]
A glass paste obtained by the same method as that of the first example using the above materials was filled into a substrate with a recess. The filling method was performed by the same screen printing as in the first example. The obtained pre-fired microlens array was subjected to preheating under the same conditions as in the first example, and then raised to about 950 ° C. at a rate of 10 ° C./min. This was maintained for about 30 minutes at this temperature and fired. The glass material melted and completely vitrified and became transparent. Then, although it naturally cooled (slow cooling) in the furnace, it can also be taken out and cooled. The softening point temperature of the glass material used in this example was about 850 ° C.

  The microlens array thus obtained was subjected to necessary steps as a counter substrate of the liquid crystal panel, and the TFT substrate and the liquid crystal were combined to assemble as a panel.

(Fourth embodiment)
Since the formation process of the substrate with recesses is the same as that of the first embodiment, the description thereof is omitted here.
[Lens substrate adjustment process]
Adjust the glass material as the lens material. In this embodiment, the lens material is adjusted with the following composition, but the present invention is not particularly limited thereto.
A) Glass main material: Glass blending ratio (% by weight)
Silicon oxide (SiO ₂ ): 47.0%
Boron oxide (B ₂ O ₃ ): 15.0%
Sodium oxide, potassium oxide: 0.5%
Germanium oxide: 37.5%
B) Binder PVB (polyvinyl butyral): 5% by weight of the main glass material
C) Solvent Ethanol: 0.2 cc / g based on the weight of glass main material
Turpineol: 0.5 cc / g based on the weight of the main glass material
D) Plasticizer Adipic acid: 3% by weight of the main glass material

  The above materials were put in a resin bottle with a lid together with zirconia balls (diameter: Φ4 mm) about 3 times the weight of the glass main material, and mixed in a ball mill apparatus for a certain time to produce a glass paste.

The obtained glass paste was printed and applied in the form of a sheet having a thickness of 25 μm by screen printing on one side of a PET film having a surface on which SiO ₂ was formed. In this embodiment, the sheet is formed by the screen printing method, but an applicator or a bar coater can also be used.

  The glass paste printed on the PET film was naturally dried, the solvent component was removed to some extent, and a semi-solid, so-called green sheet (hereinafter referred to as green sheet) was formed on the PET film.

[Lens substrate filling process]
The green sheet surface was placed so as to face the concave portion forming portion of the substrate with concave portions, and was placed on a plate of a press apparatus having a heating hot plate. The plate temperature was set to about 100 ° C., and a green sheet was pressed into the lens substrate from the PET film side at a pressure of 1 KN. The press-fitting time at this time was about 30 seconds. Thereafter, the pressure was released, and the substrate with concave portions into which the green sheet was press-fitted, that is, the microlens array before firing was taken out from the apparatus.

  The PET film adhering to the green sheet portion of the unfired microlens array taken out is peeled off, the prefired microlens array is put into an electric furnace, and the firing (melting) process is started.

  The temperature rising sequence in the electric furnace is a sequence as shown in FIG. 5. The temperature rising 1 is raised from room temperature to 500 ° C. at a rate of 5 ° C./min, and the temperature is kept at 500 ° C. for about 1 hour. did. Next, the temperature was raised to about 950 ° C. at a rate of 10 ° C./min. This was maintained for about 30 minutes at this temperature and fired. The glass material melted and completely vitrified and became transparent. Then, although it naturally cooled (slow cooling) in the furnace, it can also be taken out and cooled. The softening point temperature of the glass material used in this example was about 850 ° C.

  The microlens array thus obtained was subjected to necessary steps as a counter substrate of the liquid crystal panel, and the TFT substrate and the liquid crystal were combined to assemble as a panel.

  The microlens array obtained by the above embodiment is suitably used as a counter substrate of a liquid crystal panel used as a liquid crystal light valve in a projection display device. FIG. 8 shows a conceptual diagram of a projection display device. The projection display device 60 of this example is generally called a “liquid crystal projector”, and the white light (white light beam) emitted from the light source 61 passes through the integrator lenses 62 and 63 and the light intensity (brightness) of the white light. Distribution) is made uniform.

  The white light that has passed through the integrator lenses 62 and 63 is reflected by the mirror 64, and the blue light (B) and the green light (G) are reflected by the dichroic mirror 65 and travel toward the dichroic mirror 69. The red light (R) passes through the dichroic mirror 65, is reflected by the mirror 66, is shaped by the condenser lens 67, and travels toward the red liquid crystal light valve 68.

  Of the blue light (B) and green light (G) directed toward the dichroic mirror 69, the green light (G) is reflected by the dichroic mirror 69, shaped by the condenser lens 70, and incident on the green liquid crystal light valve 71. . The blue light (B) passes through the dichroic mirror 69, passes through the condenser lens 72, mirror 73, condenser lens 74, mirror 75, and condenser lens 76, is shaped, and enters the liquid crystal light valve 77 for blue. The

  The liquid crystal light valves 68, 71, and 77 are switching-controlled by drive circuits that operate based on the image signals of the respective colors to form images of the respective colors. The formed images of the respective colors enter the dichroic prism 78, are combined by the dichroic prism 78, and are projected onto the screen 80 through the projection lens 79.

  The above-described liquid crystal light valves 68, 71 and 77 use the TFT liquid crystal panel 90 shown in FIG. The TFT liquid crystal panel 90 is composed of a TFT substrate (liquid crystal driving substrate) 91, a liquid crystal panel counter substrate 92 bonded to the TFT substrate 91, and liquid crystal sealed in a gap between the TFT substrate 91 and the liquid crystal panel counter substrate 92. And a liquid crystal layer 93.

  The TFT substrate 91 is a substrate for driving the liquid crystal of the liquid crystal layer 93, and is provided in the vicinity of the glass substrate 91a, a number of pixel electrodes 91b provided on the glass substrate 91a, and the pixel electrode 91b. A plurality of thin film transistors (TFTs) 91c corresponding to 91b. In the TFT liquid crystal panel 90, the TFT substrate 91 and the liquid crystal panel counter substrate 92 are arranged so that the transparent electrode film (common electrode) 92 a of the liquid crystal panel counter substrate 92 and the pixel electrode 91 b of the TFT substrate 91 face each other. , They are joined at a certain distance.

  The microlens array 92b of the present invention is applied to the counter substrate 92 for the liquid crystal panel. Incident light P incident from the microlens array 92b side is condensed when passing through the microlens 92c, passes through the liquid crystal layer 93 from the opening 92e of the black matrix 92d formed on the microlens array 92b, and passes through the liquid crystal layer 93. 91. At this time, the microlens array 92b has an effect of emitting the amount of incident light without being attenuated as much as possible, and it becomes difficult to maintain a predetermined focal length or focal position even with slight deformation. However, it is a device that receives light from the light source 61 in FIG. 8 and is in a very high temperature environment and easily deforms due to linear expansion, but can maintain stable quality by applying the microlens array of the present invention. It is.

  24 ... concave portion, 25 ... substrate with concave portion, 30 ... screen printing plate, 31 ... lens substrate, 32 ... squeegee, 33 ... microlens array before firing.

Claims (8)

A method of manufacturing a microlens array having a plurality of microlenses,
A recess forming step of forming a plurality of recesses corresponding to the microlens on one surface side of the substrate surface;
A lens base material filling step of filling a paste-like lens base material kneaded with a lens material powder as the main material into the concave portion of the substrate with concave portions in which the concave portions are formed,
A firing step of vitrifying the filled lens substrate,
A method for manufacturing a microlens array. (A) Glass main material: 45% by weight or more and 75% by weight or less (B) Binder: 1% by weight or more and 10% by weight or less of glass main material A (C) Solvent: (A + B) remaining amount Including,
The method of manufacturing a microlens array according to claim 1. The (A) glass main material has a particle size of 10 nm or more and 10 μm or less.
The method of manufacturing a microlens array according to claim 1 or 2. The lens base material filling step includes
The lens substrate is filled by screen printing,
The method for manufacturing a microlens array according to any one of claims 1 to 3, wherein The lens base material filling step includes
Applying the lens base material to the smooth surface of the substrate having a smooth surface, evaporating the solvent to form a green sheet,
A pressing step of pressing and filling the green sheet into the concave portion of the substrate with the concave portion,
The method for manufacturing a microlens array according to any one of claims 1 to 3, wherein The substrate with recesses is quartz glass,
The glass main material A is
Silicon oxide (a): 35 to 70% by weight
Boron oxide (b): 10 to 25% by weight
Metal oxide (c): 8 to 50% by weight
As the main component,
(A) + (b) ≧ 50% by weight
Is,
The method for manufacturing a microlens array according to any one of claims 1 to 5, wherein The metal oxide (c) according to claim 6 is germanium oxide, bismuth oxide, tin oxide, titanium oxide, lead oxide, gadolinium oxide, lanthanum oxide, strontium oxide, antimony oxide, barium oxide, zinc oxide, aluminum oxide. , Phosphorus oxide, arsenic oxide alone or in combination of two or more,
A method for manufacturing a microlens array.   The microlens array manufactured by the manufacturing method of any one of Claim 1 to 7.

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