JP5464246B2 - Screen manufacturing method - Google Patents

Description

The present invention relates to a method for manufacturing a screen .

A display device that projects an image on a screen is known. As such a display device, a rear-type projector applied to a home theater monitor, a large-screen television, or the like is known, and the demand thereof has been increasing in recent years.
In such a rear projector, a transmissive screen is mainly used for image formation.

A transmission screen used in such a rear projector has a Fresnel lens portion on which a Fresnel lens is formed and a lens substrate such as a microlens substrate or a lenticular lens substrate on which a minute lens portion is formed. It has been.
A lens substrate used for such a transmission type screen is required to be made fine, and if the deviation from a desired shape is large, the optical characteristics are greatly affected.

Such a lens substrate is generally manufactured using a substrate with concave portions having a large number of concave portions. As a method for manufacturing the substrate with recesses, a method of manufacturing by etching using a mask having openings having a predetermined pattern is known (see, for example, Patent Document 1).
However, in the conventional method for manufacturing a substrate with concave portions, since the opening provided in the mask is fine, it is difficult to distribute the etching solution sufficiently uniformly during etching. As a result, variations occur in the shape of the formed recess, and it is difficult to form a sufficiently uniform recess.

JP 2004-287373 A

An object of the present invention is a child provide a screen manufacturing method using the substrate with concave portions having a recess variation in shape is small between each recess.

Such an object is achieved by the present invention described below.
The method for producing a screen of the present invention is a method for producing a screen having a microlens,
Obtaining a substrate with a recess having a recess;
Obtaining the shape of the microlens provided in the screen based on the shape of the recess of the substrate with the recess;
Have
The step of obtaining the substrate with recesses includes:
A mask forming step of forming a mask having a plurality of first openings on the substrate;
Etching the substrate through the first opening to form an initial recess; and
An opening area expanding step for expanding the opening area of the first opening and forming the second opening by removing a portion of the mask corresponding to the initial recess along the peripheral edge of the initial recess. When,
A second etching step of etching the substrate through the second opening;
Have
In the opening area enlarging step, a part corresponding to the initial recess of the mask is removed along the peripheral edge of the initial recess using an adhesive body having adhesiveness .
Thereby, the manufacturing method of the screen using the board | substrate with a recessed part which has a recessed part with a small dispersion | variation in a shape between each recessed part can be provided.

In the screen manufacturing method of the present invention, the average thickness of the mask is preferably 5 to 500 nm.
Thereby, the second opening can be more easily formed in the opening area expanding step.

In the screen manufacturing method of the present invention, it is preferable that the mask is formed of a laminate having a layer made of chromium and a layer mainly made of chromium oxide.
Thereby, in an opening area expansion process, while being able to remove a mask more reliably along the peripheral part of an initial stage recessed part, unintentional peeling of a mask can be prevented.

In the screen manufacturing method of the present invention, it is preferable that the first opening is formed by laser processing.
Thereby, the 1st opening part of the desired shape arranged in the desired pattern can be formed easily and accurately. In addition, the substrate with recesses can be manufactured with high productivity. In particular, the concave portion can be easily formed even on a large-area substrate.

In the screen manufacturing method of the present invention, the average diameter of the first opening is preferably 0.8 to 20 μm.
Thereby, the dispersion | variation in the curvature radius in a recessed part can be made small effectively. Moreover, in the first etching step, the shape of the initial recess formed can be made suitable.
In the method for producing a screen of the present invention, it is preferable that the etching step is performed using an etching solution containing ammonium fluoride and an acid.
Thereby, it is possible to etch the substrate more uniformly while suppressing the influence on the mask more effectively.
In the method for producing a screen of the present invention, the step of obtaining the shape of the microlens includes:
A step of applying a fluid resin material to the surface of the substrate with recesses on which the recesses are formed, and pressing the resin material with a flat plate;
A step of Ru solidifying the resin material,
A step except taking the substrate with concave portions and the flat plate,
It is preferable to have.

It is a longitudinal sectional view showing a concave portion with the substrate. It is a plan view of the concave portion with the substrate. It is a schematic longitudinal sectional view showing an example of a concave portion with the substrate manufacturing process. It is a schematic longitudinal sectional view showing an example of a concave portion with the substrate manufacturing process. Is a schematic longitudinal cross-sectional view showing an example of Ma microlenses substrate manufacturing method. Is a schematic longitudinal cross-sectional view showing an example of Ma microlenses substrate manufacturing method. With Figure 6 (f) a microlens substrate is a schematic longitudinal sectional view showing a transparently type screen. The structure of Li A projector is a diagram schematically illustrating. It is a schematic diagram which shows an example of an opening area expansion process.

Hereinafter, a method for producing a screen of the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings.
[Substrate with recess]
First, prior to a screen manufacturing method of the present invention, a description will be given of a substrate with concave portions.

Figure 1 is a longitudinal sectional view showing a concave portion with the substrate, 2 is a plan view of the concave portion with the substrate, 3, 4 is a schematic longitudinal sectional view showing the manufacturing process of the concave portion with the substrate .
The board | substrate 6 with a recessed part is manufactured by the method explained in full detail later, and has many recessed parts 61 on the surface, as shown in FIG.1 and FIG.2.
The substrate 6 with recesses may be made of any material, but is preferably made of a material that is difficult to bend and is not easily damaged. Examples of the constituent material of the substrate 6 with recesses include soda glass, crystalline glass, quartz glass, lead glass, potassium glass, borosilicate glass, and alkali-free glass. Among them, the soda glass can be easily processed in a manufacturing process as described later, and the obtained substrate 6 with concave portions can have suitable optical characteristics. Further, soda glass is relatively inexpensive and is advantageous from the viewpoint of manufacturing cost. Also, soda glass generally tends to cause a problem that a product (by-product) that is hardly soluble in water due to a reaction with an etching solution, and when such a by-product is generated, the mask 8 described later is formed. Although the initial hole may be blocked by a by-product, etc., such a problem can be effectively prevented according to the method for manufacturing a substrate with a recess as described in detail later. In particular, when an etching solution that will be described in detail later is used, the above-described problems can be prevented more reliably.

The recess 61 has a shape corresponding to the microlens 21 of the microlens substrate 1 described later. In particular, since the recess 61 is formed by the method of the present invention as described later, the variation in shape between the recesses 61 is small. Therefore, the microlens substrate 1 with little color unevenness can be easily formed.
In the present embodiment, the recess 61 has a flat shape (substantially oval or substantially bowl-shaped) whose vertical width (vertical width) when viewed in plan is smaller than the horizontal width (horizontal width). Have. When the recess 61 has such a shape, the obtained microlens substrate 1 has particularly excellent viewing angle characteristics. In particular, the viewing angle characteristics in the horizontal direction and the vertical direction are both excellent. In addition, the brightness of the projected image is higher.

  When the length in the minor axis direction (longitudinal direction) of the recess 61 in plan view is X [μm] and the length in the major axis direction (lateral direction) is Y [μm], 0.10 ≦ X / Y It is preferable to satisfy the relationship of ≦ 0.99, more preferably satisfy the relationship of 0.50 ≦ X / Y ≦ 0.95, and satisfy the relationship of 0.60 ≦ X / Y ≦ 0.80 Is more preferable. By satisfying the relationship as described above, the effects as described above become more remarkable.

Further, when the length in the minor axis direction (vertical direction) of the concave portion 61 in plan view is L ₁ [μm] and the length in the major axis direction (lateral direction) is L ₂ [μm], 0.10 ≦ L ₁ / L ₂ ≦ 0.99 is preferably satisfied, more preferably 0.50 ≦ L ₁ / L ₂ ≦ 0.95 is satisfied, and 0.60 ≦ L ₁ / L _It is more preferable to satisfy the relationship of ₂ ≦ 0.80. By satisfying the relationship as described above, the effects as described above become more remarkable.

  Further, the length in the minor axis direction of the recess 61 when viewed in plan is preferably 10 to 500 μm, more preferably 30 to 300 μm, and further preferably 50 to 100 μm. When the length of the concave portion 61 in the minor axis direction is a value within the above range, the viewing angle characteristics of the manufactured microlens substrate 1 and the contrast and brightness of the image projected by the microlens substrate 1 are particularly excellent. However, sufficient resolution can be obtained in the projected image. Further, when the length of the concave portion 61 in the short axis direction is a value within the above range, it is possible to effectively prevent the occurrence of inconvenience such as moire when the manufactured microlens substrate 1 is used. The productivity of the microlens substrate 1 (the substrate 6 with the recesses) can be further increased.

  Further, the length in the major axis direction of the concave portion 61 when viewed in plan is preferably 15 to 750 μm, more preferably 45 to 450 μm, and further preferably 70 to 150 μm. When the length of the concave portion 61 in the major axis direction is a value within the above range, the viewing angle characteristics of the manufactured microlens substrate 1 and the contrast and brightness of the image projected by the microlens substrate 1 are particularly excellent. However, sufficient resolution can be obtained in the projected image. Further, when the length of the concave portion 61 in the major axis direction is a value within the above range, it is possible to effectively prevent the occurrence of inconvenience such as moire when the manufactured microlens substrate 1 is used. The productivity of the microlens substrate 1 (the substrate 6 with the recesses) can be further increased.

  Moreover, it is preferable that the curvature radius of the recessed part 61 is 7.5-375 micrometers, It is more preferable that it is 22.5-225 micrometers, It is further more preferable that it is 35-75 micrometers. When the radius of curvature of the recess 61 is a value within the above range, the viewing angle characteristic can be made particularly excellent. In particular, both the horizontal and vertical viewing angle characteristics can be improved. The concave portion 61 may have a different radius of curvature in the minor axis direction and a radius of curvature in the major axis direction. In such a case, the radius of curvature in the minor axis direction is a value within the above range. Preferably there is.

Moreover, it is preferable that the depth of the recessed part 61 is 7.5-375 micrometers, It is more preferable that it is 22.5-225 micrometers, It is further more preferable that it is 35-75 micrometers. When the height of the recess 61 is a value within the above range, the viewing angle characteristics of the finally obtained transmission screen 10 (rear projector 300) can be made particularly excellent.
Further, when the depth of the recess 61 is H [μm] and the length of the recess 61 in the minor axis direction is X [μm], it is preferable that the relationship of 1.0 ≦ X / H ≦ 2.7 is satisfied. 1.1 ≦ X / H ≦ 2.3 is more preferable, and 1.3 ≦ X / H ≦ 2.1 is more preferable. By satisfying such a relationship, the viewing angle characteristic can be made particularly excellent while effectively preventing the occurrence of moire due to light interference.

  The plurality of recesses 61 are arranged in a staggered pattern (in a staggered pattern). By arranging the recesses 61 in this manner, it is possible to effectively prevent inconveniences such as moire in the finally obtained transmission screen 10 (rear projector 300). On the other hand, for example, if the recesses 61 are arranged in a square lattice pattern or the like, it may be difficult to sufficiently prevent the occurrence of inconvenience such as moire depending on the size of the recesses 61 and the like. Further, when the concave portions are randomly arranged, depending on the size of the concave portion 61 and the like, it becomes difficult to sufficiently increase the occupancy ratio of the concave portions in the effective region where the concave portions are formed, and light transmission of the obtained microlens substrate is difficult. It is difficult to sufficiently increase the rate (light utilization efficiency), and the obtained image becomes dark.

  As described above, the recesses 61 are arranged in a staggered pattern when the substrate 6 with recesses is viewed in plan view. However, the first rows 25 including the plurality of recesses 61 and the adjacent first rows 25 are arranged. Preferably, the second row 26 is offset by a half pitch in the vertical direction. Thereby, in the finally obtained transmissive screen 10 (rear projector 300), it is possible to more effectively prevent the occurrence of moiré due to light interference, and to have particularly excellent viewing angle characteristics. Can do.

As described above, by strictly defining the shape, arrangement method, occupation ratio, and the like of the recesses, it is possible to effectively generate moiré due to light interference in the finally obtained transmission screen 10 (rear projector 300). In particular, the viewing angle characteristics and the like can be made excellent.
Further, in the effective region where the recess 61 is formed when the substrate 6 with recess is viewed in plan, the occupation ratio of the recess 61 is preferably 90% or more, more preferably 96% or more, More preferably, it is 97% or more. When the occupation ratio of the recesses 61 is 90% or more, the light utilization efficiency of the obtained microlens substrate 1 can be further improved. Note that the occupancy rate of the concave portion 61 is such that the concave portion 61 is formed in a line segment connecting the center 612 of the concave portion 61 when viewed in plan and the central portion of the portion adjacent to the concave portion 61 where the concave portion 61 is not formed. It can be determined as a ratio (L ₃ / L ₄ × 100 [%]) between the length L ₃ [μm] of the portion that has been measured and the length L ₄ [μm] of the line segment (see FIG. 2) .

Next, an example of a manufacturing method of the concave portion with the substrate.
3, FIG. 4 is a schematic longitudinal sectional view showing an example of a concave portion with the substrate manufacturing process.
First, when manufacturing the board | substrate 6 with a recessed part, the board | substrate (glass substrate) 7 is prepared (refer Fig.3 (a)).

The substrate 7 having a uniform thickness and having no deflection or scratches is preferably used. The substrate 7 is preferably one whose surface is cleaned by washing or the like.
Such cleaning can be performed, for example, by etching (light etching) the surface of the substrate 7.
The etching method is not particularly limited, and examples thereof include wet etching and dry etching.

When wet etching is used, the etching solution is not particularly limited, but a mixed solution of ammonium monohydrogen difluoride and sulfuric acid is preferably used. Thereby, the smoothness of the surface of the substrate 7 can be increased, and impurities (Na, K, etc.) on the surface of the substrate 7 can be suitably removed. As a result, the mask forming film 4 (mask 8) can be reduced in defects such as pinholes in a masking process described later. Thereby, it can prevent etching except the opening part by a laser being etched unintentionally.
The thickness of the substrate 7 varies depending on various conditions such as the material constituting the substrate 7 and the refractive index, but is usually preferably about 0.3 to 20 mm, and more preferably about 2 to 8 mm. When the thickness is within this range, for example, a compact substrate 6 with concave portions having necessary optical characteristics can be obtained.

<A1> A mask 8 having a large number of first openings 81 is formed on the surface of the prepared substrate 7, and the back surface of the substrate 7 (the surface opposite to the surface on which the mask 8 is formed) is protected. A film 89 is formed (see mask formation step, FIG. 3A and FIG. 3B).
In particular, in the present embodiment, first, as shown in FIG. 3A, a back surface protective film 89 is formed on the back surface of the prepared substrate 7 and a mask forming film 4 is formed on the surface of the substrate 7 (mask). Then, as shown in FIG. 3B, a mask 8 is obtained by forming a first opening 81 in the mask forming film 4 (first opening forming step). The mask forming film 4 and the back surface protective film 89 can be formed simultaneously.

  The mask forming film 4 is preferably capable of forming a first opening 81 described later by laser light irradiation or the like and having resistance to etching in an etching process described later. In other words, the mask formation film 4 (mask 8) is preferably configured so that the etching rate is substantially equal to or lower than that of the substrate 7.

From this point of view, as a material constituting the mask forming film 4 (mask 8), for example, a metal such as Cr, Au, Ni, Ti, Pt, an alloy containing two or more selected from these, Examples thereof include oxides (metal oxides), silicon, and resins.
In addition, the mask forming film 4 (mask 8) may have, for example, a substantially uniform composition, or a laminated body having a plurality of different layers.

  As described above, the configuration of the mask forming film 4 (mask 8) is not particularly limited, but is a laminate having a layer mainly composed of chromium and a layer mainly composed of chromium oxide. Preferably there is. The mask forming film 4 having such a configuration can easily and reliably form an opening having a desired shape by irradiation with laser light as described later. The mask 8 obtained by using the mask forming film 4 has excellent stability with respect to etching solutions having various compositions (the substrate 7 can be more reliably protected in an etching process described later). . Further, when the mask forming film 4 (mask 8) has the above-described configuration, the thickness of the mask 8 can be reduced while maintaining the resistance to the etching solution. As a result, in a later-described etching process, when a recess in the formation process has a predetermined size, a portion of the mask corresponding to the recess can be surely removed. Further, when the mask forming film 4 (mask 8) has the above-described configuration, for example, in an etching process (a first etching process and a second etching process) described later, one hydrogen as an etching solution. A liquid containing ammonium difluoride can be suitably used. Since ammonium monohydrogen difluoride is not a poisonous deleterious substance, it is possible to prevent the human body and the environment during work more reliably. Further, the mask forming film 4 (mask 8) having the above-described configuration can relieve the internal stress of the mask efficiently, and is particularly excellent in adhesion with the substrate 7 (particularly, adhesion in the etching process). ing. As a result, in the opening area expanding process described later, the mask can be more reliably removed along the peripheral edge portion of the initial recess 61 ′, and unintentional peeling of the mask can be prevented. For this reason, by using the mask forming film 4 (mask 8) having the above-described configuration, the concave portion 61 having a desired shape can be easily and reliably formed.

  The method for forming the mask forming film 4 is not particularly limited, but the mask forming film 4 (mask 8) is made of a metal material (including an alloy) such as chromium (Cr) or gold (Au) or a metal oxide (for example, chromium oxide). ), The mask forming film 4 can be suitably formed by, for example, vapor deposition or sputtering. When the mask forming film 4 (mask 8) is made of silicon, the mask forming film 4 can be suitably formed by, for example, a sputtering method or a CVD method.

  When the mask 8 is a laminate having a layer mainly composed of chromium and a layer mainly composed of chromium oxide, the average thickness of the chromium layer is X [nm], and the average thickness of the chromium oxide layer is When the thickness is Y [nm], it is preferable to satisfy the relationship of 0.01 ≦ Y / X ≦ 0.8, and it is more preferable to satisfy the relationship of 0.1 ≦ Y / X ≦ 0.5 . By satisfying such a relationship, the first opening having a desired size can be formed with higher accuracy.

  The thickness of the mask forming film 4 (mask 8) varies depending on the material constituting the mask forming film 4 (mask 8), but is preferably 5 to 500 nm, and more preferably 40 to 150 nm. . Thereby, a 2nd opening part can be formed more easily in the opening area expansion process mentioned later. In addition, the second opening 82 can be easily formed while maintaining resistance to etching, and the size of the first opening can be controlled more easily. Further, in the etching process described later, when the concave portion in the formation process has a predetermined size, the portion corresponding to the concave portion of the mask can be surely removed. As a result, etching can be performed more uniformly. If the thickness is less than the lower limit value, the first opening formed in the first opening forming step (first opening forming step) described later, depending on the constituent material of the mask forming film 4 and the like. The shape of 81 may be distorted. In addition, when wet etching is performed in an etching process (first etching process and second etching process) described later, the masked portion of the substrate 7 may not be sufficiently protected. On the other hand, if the upper limit is exceeded, depending on the constituent material of the mask forming film 4 and the like, it becomes difficult to form the first opening 81 penetrating in the first opening forming step to be described later. The mask forming film 4 (mask 8) may be easily peeled off due to internal stress of the forming film 4 (mask 8).

  The back surface protective film 89 is for protecting the back surface of the substrate 7 in the subsequent steps. By this back surface protective film 89, erosion, deterioration, etc. of the back surface of the substrate 7 are preferably prevented. The back surface protective film 89 has the same configuration as the mask forming film 4 (mask 8), for example. Therefore, the back surface protective film 89 can be provided in the same manner as the mask forming film 4 simultaneously with the formation of the mask forming film 4.

Next, as shown in FIG. 3B, a plurality of first openings 81 are formed in the mask forming film 4 to obtain a mask 8 (first opening forming step). The first opening 81 formed in this step functions as a mask opening in the first etching described later.
The method for forming the first opening 81 is not particularly limited, but is preferably a method using laser light irradiation. Thereby, the first openings 81 having a desired shape arranged in a desired pattern can be easily and accurately formed. As a result, the shape, arrangement method, and the like of the recesses 61 can be controlled more reliably. Further, by forming the first opening 81 by laser irradiation, the substrate with a recess can be manufactured with high productivity. In particular, the concave portion can be easily formed even on a large-area substrate. Further, by forming the first opening 81 in the mask forming film 4 by laser light irradiation, it is simpler and less expensive than the case where the opening is formed in the resist film by a conventional photolithography method. A first opening can be formed.

Further, when the first opening 81 is formed by laser light irradiation, the type of laser light to be used is not particularly limited, but a ruby laser, a semiconductor laser, a YAG laser, a femtosecond laser, a glass laser, a YVO ₄ laser. , Ne—He laser, Ar laser, CO ₂ laser, excimer laser, and the like. Moreover, you may use wavelengths, such as SHG of each laser, THG, and FHG.

Although the shape and size of the first opening 81 formed in this step are not particularly limited, the first opening 81 is substantially circular and preferably has a diameter of 0.8 to 20 μm, preferably 1.0 to 10 μm. Is more preferable, and it is still more preferable that it is 1.5-4 micrometers. Since the first opening 81 has such a fine size, variation in the radius of curvature in the finally obtained recess 61 can be effectively reduced. In addition, in the first etching process described later, the shape of the initial recess 61 ′ to be formed can be made suitable.
In addition to forming the first opening 81 by irradiating the mask forming film 4 with laser light, for example, when the mask forming film 4 is formed on the substrate 7, a predetermined value is previously formed on the substrate 7. It is also possible to form a defect in the mask forming film 4 by forming foreign matter in a pattern and forming the mask forming film 4 thereon, and to use the defect as the first opening 81.

<A2> Next, as shown in FIG. 3C, the substrate 7 is etched using the mask 8 in which the first opening 81 is formed to form the initial recess 61 ′ (first etching). Process).
In this step, the width of the initial recess 61 ′ to be formed in plan view is larger than the width of the recess 61 to be finally formed in plan view (length in the major axis direction). It is preferable to apply until it becomes about 20-70%, and it is more preferable to apply until it becomes about 30-65%. Thereby, in the board | substrate 6 with a recessed part finally formed, the dispersion | variation in the shape between each recessed part 61 can be made small more effectively.

The etching method is not particularly limited, and examples thereof include wet etching and dry etching. In the following description, a case where wet etching is used will be described as an example.
By performing etching (wet etching) on the substrate 7 covered with the mask 8 in which the first opening 81 is formed, first, the substrate 7 has a portion where the mask 8 does not exist (the first of the mask 8). The portion corresponding to the opening 81) is gradually etched to form an initial recess 61 ′ on the substrate 7 (see FIG. 3C).

The etching solution is not particularly limited, and any one may be used, but it is preferable to use ammonium fluoride. As ammonium fluoride, there are a normal salt (NH ₄ F) and a hydrogen salt (NH ₄ HF ₂ : ammonium monohydrogen difluoride), any of which may be used, and those containing both. It may be used.
In particular, when ammonium fluoride containing ammonium monofluoride as a main component is used as the ammonium fluoride, the substrate 7 can be etched more efficiently. Moreover, since the ammonium monohydrogen difluoride solution is not a poisonous and deleterious substance, the influence on the human body and the environment during work can be prevented.

  The content of ammonium fluoride in the etching solution is not particularly limited, but is preferably 1 to 500 g / L, more preferably 1 to 200 g / L, and further preferably 10 to 100 g / L. preferable. Thereby, the substrate 7 can be etched more efficiently. On the other hand, if the content of ammonium fluoride is less than the lower limit, a sufficient etching rate may not be obtained depending on conditions such as the temperature of the etching solution. Moreover, when content of ammonium fluoride exceeds the said upper limit, sufficient effect only corresponding to content may not be acquired.

In addition to the ammonium fluoride described above, the etching solution may contain an acid. Such acids, when dissolved in water, F ^- ions and HF ₂ ^- as long as it is an acid which does not cause ions are not particularly limited, for example, sulfuric, hydrochloric, inorganic acids such as nitric acid, acetic acid, Organic acids such as succinic acid can be mentioned, and among these, one kind or a combination of two or more kinds can be used. Among these, inorganic acids are preferably used, oxo acids such as sulfuric acid and nitric acid are more preferably used, and sulfuric acid is more preferably used. Thereby, the by-product of reaction of etching liquid and glass can be removed more effectively, and it can prevent effectively that the 1st opening part 81 is blocked up inadvertently. In particular, when a laminated body having a layer mainly composed of chromium and a layer mainly composed of chromium oxide is used as the mask 8, an etching solution containing sulfuric acid is used to form the mask 8. It is possible to etch the substrate 7 more uniformly while suppressing the influence more effectively.

  Although the acid content in the etching solution is not particularly limited, it is preferably 1.7 to 920 g / L, more preferably 1.7 to 370 g / L, and 1.7 to 190 g / L. More preferably. Thereby, the by-product of reaction with etching liquid and glass can be removed more effectively. On the other hand, if the acid content is less than the lower limit, depending on the composition of the substrate 7 and the ammonium fluoride content, the above-described effects may not be sufficiently exhibited. If the acid content exceeds the upper limit, the mask 8 may be unintentionally affected depending on the composition of the mask 8, the content of ammonium fluoride, and the like.

  When the content of ammonium fluoride in the etching solution is A [g / L] and the content of acid is B [g / L], the relationship of 1.0 ≦ B / A ≦ 4.0 is satisfied. It is more preferable that the relationship of 1.0 ≦ B / A ≦ 3.0 is satisfied, and it is more preferable that the relationship of 1.3 ≦ B / A ≦ 2.7 is satisfied. Thereby, it is possible to etch the substrate 7 more uniformly and efficiently while more effectively removing the by-product of the reaction between the etchant and the glass.

Note that the etching solution may contain a solvent such as water in addition to the above-described ammonium fluoride and acid.
In addition to the above components, the etching solution may contain additives such as hydrogen peroxide and a surfactant. By including such an additive, the substrate 7 can be etched more uniformly. Among those mentioned above, particularly when hydrogen peroxide is included, the etching speed can be made faster.

<A3> Next, by removing the portion corresponding to the initial concave portion 61 ′ of the mask 8 along the peripheral edge portion of the initial concave portion 61 ′, the opening area of the first opening portion 81 is expanded, and the second opening The part 82 is formed (opening area expanding step).
As described above, the present invention is characterized in that etching is performed using the mask having the first opening, and the etching is temporarily interrupted to enlarge the area of the opening. Thereby, when performing further etching after that, etching liquid can fully be spread in the recessed part currently formed. As a result, it is possible to suppress variations in the etching rate between the recesses that are being formed, and in the finally obtained substrate with recesses, it is possible to reduce variations in shape between the recesses. By using the concave portion with the substrate obtained in this manner, it is possible to form the microlens substrate and the like is less luminance unevenness and color unevenness.

On the other hand, when etching is performed without forming the second opening, the size of the first opening is so small that it does not sufficiently reach the recess where the etching solution is being formed. For this reason, it becomes difficult to suppress the variation in shape between the concave portions, and in the finally obtained microlens substrate, the occurrence of luminance unevenness, color unevenness and the like becomes remarkable.
In this embodiment, the site | part corresponding to initial stage recessed part 61 'of the mask 8 is removed using the adhesive sheet (adhesive body) 9 which has adhesiveness.

Specifically, first, as shown in FIG. 3 (d), the adhesive sheet 9 is attached to the mask 8.
Next, as shown in FIG. 4 (e), the adhesive sheet 9 is gradually peeled off from the mask 8. Thereby, the portion of the mask 8 that is in close contact with the substrate 7 remains on the substrate 7 as it is, and the portion corresponding to the initial recess 61 ′ is removed together with the adhesive sheet 9. That is, since the site | part corresponding to initial stage recessed part 61 'is not closely_contact | adhered with the board | substrate 7, it is removed in the state affixed on the adhesive sheet 9 along the peripheral part of initial stage recessed part 61'.
Thereby, as shown in FIG. 4F, a mask 8 having a second opening is formed.

Since the second opening 82 can be more easily formed by using the adhesive sheet (adhesive body) 9 as in the present embodiment, the substrate 6 with the recesses having a small variation in shape between the recesses. Can be manufactured more easily.
The adhesive strength of the adhesive sheet 9 measured according to JIS Z 0237 varies depending on the thickness of the mask 8, the constituent material, etc., but is preferably 1.0 to 3.5 N / 25 mm, and is preferably 1.0 to 3 More preferably, it is 2 N / 25 mm, and further preferably 1.2 to 2.5 N / 25 mm. Thereby, the part corresponding to the initial recess 61 ′ of the mask 8 can be removed more reliably, and unintentional peeling of the mask 8 can be more effectively prevented. On the other hand, if the adhesive strength is less than the lower limit value, the portion corresponding to the initial recess 61 ′ of the mask 8 may not be sufficiently removed depending on the thickness of the mask 8 or the constituent material. On the other hand, if the adhesive strength exceeds the upper limit, depending on the thickness of the mask 8, the constituent material, etc., the mask 8 may be unintentionally peeled off (parts other than the part corresponding to the initial recess 61 ′ of the mask 8). May be difficult to prevent.

<A4> Next, the substrate 7 is further etched through the second opening (second etching step).
As the etching proceeds, a recess 61 is formed as shown in FIG. Thereby, the board | substrate 6 with a recessed part is formed.
<A5> Next, the mask 8 is removed (mask removal step). Further, at this time, the back surface protective film 89 is also removed together with the removal of the mask 8, whereby the substrate 6 with recesses is obtained (see FIG. 4H).
When the mask 8 is a laminated body having a layer mainly composed of chromium and a layer mainly composed of chromium oxide as described above, the removal of the mask 8 is, for example, ceric ammonium nitrate and perchlorine. The etching can be performed using a mixture containing an acid.

Further, for example, a mold release process may be performed on the surface side of the substrate 6 with the recesses where the recesses 61 are provided. Thereby, in the manufacturing method of the microlens substrate 1 described in detail later, the substrate 6 with recesses can be easily removed while sufficiently preventing defects such as chipping in the microlens 21 of the substrate body 2. . Examples of the mold release treatment include formation of a film composed of a material having releasability such as silicone resin such as alkylpolysiloxane, fluorine resin such as polytetrafluoroethylene, hexamethyldisilazane ([(CH ₃ ) Surface treatment with a silylating agent such as ₃ Si] ₂ NH), surface treatment with a fluorine-based gas, and the like.
As described above, as shown in FIGS. 1 and 2, the substrate 6 with recesses in which a large number of recesses 61 are formed in a staggered pattern on the substrate 7 is obtained.

Next, a method for manufacturing the microlens substrate 1 using the above-described substrate 6 with recesses will be described.
5 and 6 are schematic longitudinal sectional views showing an example of a method for manufacturing a microlens substrate. In the following description, the lower side in FIGS. 5 and 6 is referred to as “(light) incident side” and the upper side is referred to as “(light) emission side”.

  <B1> First, as shown in FIG. 5A, the resin material 23 having fluidity (for example, the resin material 23 in a softened state, An unpolymerized (uncured) resin material 23) is applied, and the resin material 23 is pressed by the flat plate 11. In particular, in this embodiment, the resin material 23 is pressed in a state where the spacer 20 is disposed between the substrate 6 with recesses and the flat plate 11. Thereby, the thickness of the microlens substrate 1 to be formed can be more reliably controlled, and the focal position of the microlens 21 on the finally obtained microlens substrate 1 can be more reliably controlled. And the occurrence of inconvenience such as color unevenness can be more effectively prevented.

  The spacer 20 is made of a material having a refractive index comparable to that of the resin material 23 (solidified resin material 23). By using the spacer 20 made of such a material, even when the spacer 20 is arranged at the portion where the recess 61 of the substrate 6 with recesses is formed, the microlens substrate 1 from which the spacer 20 is obtained can be obtained. An adverse effect on optical characteristics can be effectively prevented. Accordingly, it is possible to arrange a relatively large number of spacers 20 over substantially the entire effective area of the main surface (the surface side where the recesses are formed) of the substrate 6 with recesses. As a result, the substrate 6 with recesses, the flat plate Therefore, the thickness of the resulting microlens substrate 1 can be more reliably controlled.

  As described above, the spacer 20 is made of a material having the same refractive index as that of the resin material 23 (the resin material 23 after solidification). More specifically, the absolute refraction of the constituent material of the spacer 20 is used. The absolute value of the difference between the refractive index and the absolute refractive index of the resin material 23 after solidification is preferably 0.20 or less, more preferably 0.10 or less, and further preferably 0.02 or less. Preferably, the solidified resin material 23 and the spacer 20 are most preferably composed of the same material.

The shape of the spacer 20 is not particularly limited, but is preferably substantially spherical or substantially cylindrical. When the spacer 20 has such a shape, the diameter is preferably 10 to 300 μm, more preferably 30 to 200 μm, and still more preferably 30 to 170 μm.
In the case where the spacer 20 is used as described above, when the resin material 23 is solidified, it is sufficient that the spacer 20 is disposed between the substrate 6 with recesses and the flat plate 11, and the timing for supplying the spacer 20 is particularly It is not limited. For example, the resin material 23 in which the spacer 20 is dispersed in advance as the resin to be applied may be used on the surface of the substrate 6 with the recess where the recess 61 is formed, or the spacer 20 is disposed on the substrate 6 with the recess. The resin material 23 may be applied in a state, or the spacer 20 may be applied after the resin material 23 is supplied.
Further, the flat plate 11 may have a surface on which the resin material 23 is pressed subjected to the release treatment as described above. Thereby, the flat plate 11 can be efficiently removed from the surface of the substrate body 2 in a process described later.

<B2> Next, the resin material 23 is solidified (including curing (polymerization)), and then the flat plate 11 is removed (see FIG. 5B). Thereby, the substrate main body 2 provided with the microlens 21 (particularly, the microlens 21 satisfying the conditions such as the shape and the arrangement as described above) made of the resin filled in the concave portion 61 is obtained.
When the resin material 23 is solidified by curing (polymerization), examples of the method include irradiation with light such as ultraviolet rays, irradiation with electron beams, and heating.

<B3> Next, as shown in FIG. 5C, a colored black matrix-forming material (light-shielding film-forming material) is applied to the exit-side surface of the substrate body 2, and the black matrix-forming material is used. The formed film 32 is formed (light shielding film forming material application step).
As a black matrix forming material, any material may be used as long as it has a function of absorbing external light (external light which is not preferable for forming a projection image). For example, various inorganic materials, various organic materials, composite materials of inorganic materials and organic materials, and the like can be used. More specifically, chromium oxide, chromium, various pigments, various dyes, and the like can be used.

  The film 32 may be composed of a plurality of types of materials, for example, a laminate having a layer mainly composed of chromium and a layer mainly composed of chromium oxide. When the film 32 (black matrix 3) has such a configuration, the opening 31 can be easily and reliably formed by a method as described later, and the durability of the black matrix 3 is particularly excellent. Can be.

  The method for applying the black matrix forming material to the surface of the substrate body 2 is not particularly limited. For example, dip coating, doctor blade, spin coating, brush coating, spray coating, electrostatic coating, electrodeposition coating, roll coater, etc. Various coating methods, vapor deposition methods, ion plating methods, vapor phase film formation methods such as sputtering methods, wet plating methods such as electrolytic plating and electroless plating, and the like can be applied. In particular, when the black matrix 3 is formed as a laminate having a layer mainly composed of chromium and a layer mainly composed of chromium oxide, the film 32 is preferably formed by a vapor deposition method. Further, when the black matrix 3 is formed as a material composed of a material containing a pigment or dye (particularly, a material composed of a material including a resin material in addition to the pigment or dye), the black matrix 3 is formed by a coating method. Is preferred. Thereby, the film | membrane 32 of uniform thickness can be formed easily.

  When the black matrix 3 is formed of a material including a pigment or a dye, the black matrix forming material includes a resin material and a liquid medium (for example, a solvent, a dispersion medium, in addition to the pigment and the dye). A liquid that functions as a liquid). Thereby, the film 32 having a uniform thickness can be formed easily and reliably, and the adhesion of the formed film 32 (black matrix 3) to the substrate body 2 can be made particularly excellent. . Further, if the black matrix forming material is composed of a material including a resin material and a liquid medium in addition to a pigment and a dye, a predetermined portion of the film 32 is formed in an opening forming step described in detail later. Can be easily and reliably removed, and the black matrix 3 having the openings 31 having a desired shape can be more reliably formed.

In this step, a treatment for removing a part of the components constituting the black matrix forming material may be performed in the subsequent step. For example, when the black matrix forming material is made of a material containing a liquid medium, for example, a process for removing the liquid medium from the film 32 made of the black matrix forming material (for example, heat treatment) , Decompression treatment or the like).
The thickness of the film 32 formed in this step is usually substantially the same as the thickness of the black matrix 3. Therefore, the thickness (average thickness) of the film 32 is preferably 0.3 to 8.0 μm, more preferably 0.8 to 7.0 μm, and 1.4 to 6.0 μm. Is more preferable.

  <B4> Next, as shown in FIG. 6D, the substrate body 2 is removed from the substrate 6 with recesses. Thus, by removing the substrate 6 with recesses from the substrate body 2, the removed substrate 6 with recesses can be repeatedly used for the manufacture of the substrate body 2 (microlens substrate 1). This is advantageous for improving the stability of the quality of the substrate body 2 (microlens substrate 1).

  <B5> Next, as shown in FIG. 6E, the substrate main body 2 is irradiated with laser light Lb in a direction perpendicular to the incident-side surface. The irradiated laser beam Lb is refracted and collected by entering the microlens 21. And the film | membrane (film | membrane comprised with the material for light shielding film formation) 32 of the site | part irradiated with the laser beam which became high energy by condensing is removed, and the opening part 31 is formed (FIG. 6 ( f)). Thereby, the microlens substrate 1 having the black matrix (light shielding film) 3 is obtained.

In particular, the substrate main body 2, since it is those formed with the concave portion with the substrate, the substrate main body 2 has a smaller variation in shape between the respective microlenses 21. Therefore, the opening 31 corresponding to each microlens 21 can be more reliably formed.
In addition, by utilizing the light (particularly, laser light having a uniform frequency and phase) collected by the microlens, the number of steps is reduced, and an opening having a desired shape can be formed in a desired portion with a simple method. It is possible to reliably form a light shielding film having As a result, an image obtained by using the microlens substrate can have excellent light utilization efficiency and excellent contrast.

In addition, since the laser light is generally light having a uniform frequency and phase, by selecting the type of laser light according to the film made of the light shielding film forming material and the constituent material of the microlens substrate, It is possible to more reliably prevent the occurrence of adverse effects on the portions of the film composed of the substrate body and the light shielding film forming material that should remain.
The type of laser light used in this step is not particularly limited. For example, ruby laser, semiconductor laser, YAG laser, femtosecond laser, glass laser, YVO ₄ laser, Ne-He laser, Ar laser, CO ₂ laser, excimer A laser etc. are mentioned. Moreover, you may use wavelengths, such as SHG of each laser, THG, and FHG.
Note that the above-described series of processes of applying the light-shielding film forming material and irradiating the laser beam may be repeated. Thereby, the light shielding film (black matrix) can be formed thicker, and the contrast can be further improved.

Next, the transmission screen 10 including the microlens substrate 1 as described above will be described.
7 is provided with a micro lens substrate shown in FIG. 6 (f), it is a schematic longitudinal sectional view showing a transparently type screen.
As shown in FIG. 7, the transmission screen 10 includes a Fresnel lens portion 5 and the microlens substrate 1 described above. The Fresnel lens unit 5 is installed on the light (image light) incident side, and the light transmitted through the Fresnel lens unit 5 is incident on the microlens substrate 1.

The Fresnel lens unit 5 has a prism-shaped Fresnel lens 51 formed in a substantially concentric shape on the exit side surface. The Fresnel lens unit 5 refracts image light from a projection lens (not shown) to produce parallel light La parallel to the vertical direction of the main surface of the microlens substrate 1.
In the transmissive screen 10 configured as described above, the image light from the projection lens is refracted by the Fresnel lens unit 5 and becomes parallel light La. The parallel light La is incident on the surface of the microlens substrate 1 opposite to the surface on which the black matrix 3 is provided, is condensed by each microlens 21, is focused, and is diffused. At this time, the light incident on the microlens substrate 1 is transmitted through the microlens substrate 1 with sufficient transmittance. The light that has passed through the opening 31 diffuses and is observed as a planar image by the observer.
Since the transmissive screen 10 includes the microlens substrate 1 described above, an excellent image with little color unevenness can be displayed.

Next, a rear projector using the transmission screen will be described.
Figure 8 is a diagram schematically showing a configuration of the re-A type projector.
As shown in the figure, the rear projector 300 has a configuration in which a projection optical unit 310, a light guide mirror 320, and a transmissive screen 10 are arranged in a housing 340.
Since the rear projector 300 uses the above-described transmission screen 10 as the transmission screen 10, the rear projector 300 is an excellent rear projector with good display quality.

The screen manufacturing method of the present invention has been described based on the illustrated embodiments, but the present invention is not limited to these.
For example, in the method for producing a screen of the present invention, an optional process can be added as necessary.

In the above-described embodiment, the second opening is formed using an adhesive. However, the present invention is not limited to this. For example, the second opening may be formed by physical means such as laser, water pressure, reduced pressure, and sandblast.
In the above-described embodiment, the case where a sheet-like adhesive is used as an adhesive used for removing the portion corresponding to the initial concave portion of the mask is not limited to this. For example, as shown in FIG. By providing an adhesive layer (adhesive body) 9 ′ on the surface of the roller and rolling the roller on the surface of the mask 8, a portion corresponding to the initial recess 61 ′ of the mask 8 may be removed. Thereby, the site | part corresponding to initial stage recessed part 61 'of the mask 8 can be removed still more easily.

  In the above-described embodiment, the spacer has been described as having a refractive index comparable to that of the resin (resin after solidification). However, the spacer is substantially formed with a concave portion of the substrate with the concave portion. In the case of being disposed only in the non-effective region (ineffective region), it may not have a refractive index comparable to that of the resin (resin after solidification). In manufacturing the lens substrate, the spacer as described above is not necessarily used.

In the above-described embodiment, the resin is applied to the surface of the substrate with recesses. However, for example, a lens substrate is manufactured by applying resin to the surface of a flat plate and pressing it with the substrate with recesses. May be.
Moreover, in embodiment mentioned above, in manufacture of a microlens board | substrate, a board | substrate with a recessed part does not necessarily need to be removed as what remove | eliminates a board | substrate with a recessed part. In other words, the substrate with concave portions may constitute a part of the lens substrate.

In the above-described embodiment, the black matrix opening is formed after the substrate with the recess is removed from the substrate body. However, the formation of the opening (irradiation with laser light) is performed on the substrate with the recess. May be done before removing. Moreover, you may perform provision of the material for light shielding film formation after removing a board | substrate with a recessed part.
Further, in the embodiment described above, the transmission type screen has been described as comprising a microlens substrate and a Fresnel lens, transparently type screen may not necessarily those with a Fresnel lens. For example, transparently type screen is substantially or may be formed only with the microlens substrate.

In addition, the microlens substrate and the transmissive screen may include a diffusing portion and a diffusing plate having a function of diffusing light transmitted through the substrate body. With such a configuration, for example, the viewing angle characteristics of a transmissive screen and a rear projector can be made particularly excellent.
Further, in the embodiment described above, the lens substrate (microlens substrate) is a transmission screen, has been described as a member constituting the rear projection, the microlens substrate applications, limited to the like It can be anything. For example, the microlens substrate is applied to a diffusion plate, a black matrix screen, a projection display device (front projector) screen (front projection screen), a component of a liquid crystal light valve of the projection display device (front projector), and the like. It may be a thing.

[Production of microlens substrate and transmissive screen]
Example 1
A substrate with recesses having recesses for forming microlenses was manufactured as follows.
First, a soda glass substrate (absolute refractive index n ₂ : 1.50) having a width of 1.2 m × length of 0.7 m and a thickness of 4.8 mm was prepared as a substrate.

This soda glass substrate was immersed in a cleaning solution containing 4 wt% ammonium monohydrogen difluoride and 7.36 wt% concentrated sulfuric acid and etched by 6 μm to clean the surface.
Thereafter, cleaning with pure water and drying using N ₂ gas (removal of pure water) were performed.
Next, on this soda glass substrate, a chromium oxide / chromium / chromium oxide laminate (a second layer of chromium and a third layer of chromium oxide are formed on the first layer of chromium oxide) by sputtering. The laminated body laminated | stacked in order) was formed. That is, a mask forming film and a back surface protective film made of a chromium oxide / chromium / chromium oxide laminate were formed on the surface of a soda glass substrate. The thickness of the first layer was 0.01 μm, the thickness of the second layer was 0.05 μm, and the thickness of the third layer was 0.05 μm.

Next, laser processing was performed on the mask formation film to form a large number of first openings in a range of 113 cm × 65 cm in the central portion of the mask formation film, thereby forming a mask.
The laser processing was performed using a YAG laser under the conditions of an energy intensity of 1 mW, a beam diameter of 3 μm, and a scanning speed of 0.1 m / second.
As a result, a first opening having a predetermined size was formed in a staggered pattern over the entire range of the mask forming film. The average diameter of the first opening was 2 μm.

Next, wet etching was performed on the soda glass substrate (first etching step). In the wet etching, an aqueous solution containing 4 wt% ammonium monohydrogen difluoride and 7.36 wt% concentrated sulfuric acid was used as an etchant.
Next, wet etching was performed on the soda glass substrate to form an initial recess (first etching step).
Note that the etching was temporarily interrupted when the width of the initial recess in plan view (the width of the initial recess) reached 50% of the width of the recess to be formed in plan view (width of the recess).

Next, the surface of the mask was washed and dried.
Next, an adhesive sheet (manufactured by Sumitomo 3M, trade name “Plating Tape # 851A”) was attached to the mask surface. In addition, the adhesive force of the adhesive sheet was 2.0 N / 25 mm.
Next, while removing the stuck adhesive sheet, the site | part corresponding to the initial stage recessed part of a mask was removed, and the 2nd opening part was formed (opening area expansion process). The diameter of the second opening was 41 μm. The mask was removed along the peripheral edge of the initial recess.

  Next, wet etching was performed on the soda glass substrate through the second opening in the same manner as described above (second etching step). Thereby, a concave portion (a concave portion for forming a microlens) having a flat shape (substantially elliptical shape) when viewed in plan was formed on the soda glass substrate. The formed many recesses had substantially the same shape as each other. The length of the formed recess in the minor axis direction was 54 μm, the length in the major axis direction (width of the recess) was 82 μm, the radius of curvature was 38 μm, and the depth was 38 μm. Moreover, the occupation rate of the recessed part in the effective area | region in which the recessed part was formed was 100%.

Next, the mask and the back surface protective film were removed by etching using a mixture of ceric ammonium nitrate and perchloric acid.
Next, cleaning with pure water and drying using N ₂ gas (removal of pure water) were performed.
Thereafter, a gas phase surface treatment (silylation treatment) with hexamethyldisilazane was performed on the surface side of the substrate where the concave portions were formed, thereby forming a release treatment portion.

As a result, a substrate with recesses in which a large number of recesses for forming microlenses were arranged in a staggered pattern on a soda glass substrate as shown in FIG. When the obtained substrate with recesses was viewed in plan, the ratio of the area occupied by the recesses in the effective region where the recesses were formed was 100%.
Next, unpolymerized (uncured) acrylic resin (PMMA resin (methacrylic resin)) was applied to the surface of the substrate with recesses on the side where the recesses were formed. Under the present circumstances, the substantially spherical spacer (diameter 50 micrometers) comprised with the hardened | cured material of acrylic resin (PMMA resin (methacrylic resin)) was distribute | arranged to the substantially whole surface of the board | substrate with a recessed part. The spacers were arranged at a rate of about 3 pieces / cm ² .

Next, the acrylic resin was pressed with a flat plate made of soda glass. At this time, air was prevented from entering between the flat plate and the acrylic resin. Moreover, as a flat plate, the surface on which the acrylic resin is pressed is subjected to a gas phase surface treatment (mold release treatment) with hexamethyldisilazane.
Thereafter, the acrylic resin was cured by heating to 120 ° C., and a substrate provided with a large number of microlenses (microlenses having no flat portion) was obtained. The refractive index n ₁ of the obtained substrate (cured resin) was 1.51. The thickness of the resin layer (excluding the microlens) of the obtained substrate was 50 μm. The flat (substantially oval) microlens had a short axis length of 54 μm, a long axis length of 82 μm, a radius of curvature of 38 μm, and a height of 38 μm. Further, the occupation ratio of the microlens in the effective region where the microlens is formed was 100%.

Next, the flat plate was removed.
Next, a colored light-shielding film forming material containing a black pigment was applied to the surface of the substrate on the emission side (surface opposite to the surface on which the microlenses are formed) by a roll coater (light-shielding film forming material). Application step). As the light-shielding film forming material, a mixture containing 10 wt% black pigment, 20 wt% damar resin, and 70 wt% xylene (liquid medium) was used.

Thereafter, xylene was removed from the light-shielding film forming material applied to the substrate, thereby forming a film covering the entire emission side of the substrate. The average thickness of the formed film was 5 μm.
Next, the substrate with recesses was removed from the substrate provided with the light shielding film forming material. As a result, the laser light is condensed by the microlens, and only the portion of the film near the focal point of the microlens is selectively removed, and the substrate is covered with a black matrix having a large number of openings. Thus obtained microlens substrate was obtained. The opening was substantially circular and the average diameter was 20 μm. The thickness of the formed black matrix was 5 μm.
A transmissive screen as shown in FIG. 7 was obtained by assembling the microlens substrate manufactured as described above and the Fresnel lens portion manufactured by extrusion molding.

(Example 2)
A microlens substrate and a transmissive screen were produced in the same manner as in Example 1 except that the adhesive sheet was changed to the trade name “Sumilon E-75M” manufactured by Sumilon. In addition, the adhesive force of the adhesive body was 3.2 N / 25 mm.
(Example 3)
A microlens substrate and a transmissive screen were produced in the same manner as in the above example except that the pressure-sensitive adhesive sheet was changed to a roller as shown in FIG. 9 (a roller having a pressure-sensitive adhesive body on the surface). In addition, the adhesive force of the adhesive body was 2.0 N / 25 mm.

Example 4
In the first etching step, etching was performed in the same manner as in Example 1 except that the etching was performed until the width of the initial concave portion in plan view reached 30% of the width of the concave portion to be formed in plan view. Thus, a microlens substrate and a transmission screen were manufactured.
(Example 5)
In the first etching step, etching was performed in the same manner as in Example 1 except that the width when the initial concave portion was viewed in plan reached 70% of the width when the concave portion to be formed was viewed in plan. Thus, a microlens substrate and a transmission screen were manufactured.

(Example 6)
The microlens substrate and the transmissive screen were the same as in Example 1 except that a chromium / chromium oxide laminate (a laminate in which chromium oxide was laminated on the outer surface side of chromium) was used as the mask forming film. Manufactured. The chromium layer had a thickness of 0.03 μm, and the chromium oxide layer had a thickness of 0.01 μm.

(Example 7)
By adjusting the diameter and pitch of the first opening and the immersion time in the etching solution when forming the substrate with recesses, the shape and arrangement pattern of the recesses of the substrate with recesses are as shown in Table 1. A microlens substrate and a transmissive screen were produced in the same manner as in Example 1 except that.

(Comparative example)
A substrate with recesses having recesses for forming microlenses was manufactured as follows.
First, a soda glass substrate (absolute refractive index n ₂ : 1.50) having a width of 1.2 m × length of 0.7 m and a thickness of 4.8 mm was prepared as a substrate.
This soda glass substrate was immersed in a cleaning solution containing 4 wt% ammonium monohydrogen difluoride and 8 wt% hydrogen peroxide and etched by 6 μm to clean the surface.

Thereafter, cleaning with pure water and drying using N ₂ gas (removal of pure water) were performed.
Next, a chromium / chromium oxide laminate (a laminate in which chromium oxide was laminated on the outer surface side of chromium) was formed on the soda glass substrate by sputtering. That is, a mask and a back surface protective film made of a chromium / chromium oxide laminate were formed on the surface of the soda glass substrate. The thickness of the chromium layer was 0.03 μm, and the thickness of the chromium oxide layer was 0.01 μm.

Next, laser processing was performed on the mask to form a large number of openings in a range of 113 cm × 65 cm at the center of the mask.
The laser processing was performed using a YAG laser under the conditions of an energy intensity of 1 mW, a beam diameter of 3 μm, and a scanning speed of 0.1 m / second.
As a result, substantially circular openings were formed in a staggered pattern over the entire range of the mask. The average diameter of the openings was 2 μm.

  Next, wet etching was performed on the soda glass substrate to form concave portions (recesses for forming microlenses) having a flat shape (substantially elliptical shape) when viewed in plan on the soda glass substrate. Variations were observed in the shapes of the many formed recesses. The length of the formed recess in the minor axis direction was 70 μm, and the length in the major axis direction was 107 μm. Moreover, the curvature radius of the recessed part was 53.5 micrometers, and the depth was 50.0 micrometers.

In the wet etching, an aqueous solution containing 4 wt% ammonium monohydrogen difluoride and 8 wt% hydrogen peroxide was used as an etchant, and the immersion time was 2.0 hours.
Next, the mask and the back surface protective film were removed by etching using a mixture of ceric ammonium nitrate and perchloric acid.
Next, cleaning with pure water and drying using N ₂ gas (removal of pure water) were performed.

Thereafter, a gas phase surface treatment (silylation treatment) with hexamethyldisilazane was performed on the surface side of the substrate where the concave portions were formed, thereby forming a release treatment portion.
As a result, a substrate with recesses in which a large number of recesses for forming microlenses were arranged in a staggered pattern on a soda glass substrate as shown in FIG. When the obtained substrate with recesses was viewed in plan, the ratio of the area occupied by the recesses was 98% in the effective region where the recesses were formed.

Next, unpolymerized (uncured) acrylic resin (PMMA resin (methacrylic resin)) was applied to the surface of the substrate with recesses on the side where the recesses were formed. Under the present circumstances, the substantially spherical spacer (diameter 50 micrometers) comprised with the hardened | cured material of acrylic resin (PMMA resin (methacrylic resin)) was distribute | arranged to the substantially whole surface of the board | substrate with a recessed part. The spacers were arranged at a rate of about 3 pieces / cm ² .

Next, the acrylic resin was pressed with a flat plate made of soda glass. At this time, air was prevented from entering between the flat plate and the acrylic resin. Moreover, as a flat plate, the surface on which the acrylic resin is pressed is subjected to a gas phase surface treatment (mold release treatment) with hexamethyldisilazane.
Thereafter, the acrylic resin was cured by heating to 120 ° C. to obtain a substrate body. Further, the thickness of the resin layer (excluding the microlens) of the obtained substrate body was 80 μm. Further, the flat (substantially elliptical) microlens has a short axis length (diameter) of 70 μm, a long axis length of 107 μm, a radius of curvature of 53.5 μm, and a height of 50.0 μm. there were. Further, the occupation ratio of the microlens in the effective region where the microlens is formed was 98%.

Next, the flat plate was removed.
Next, a colored light-shielding film forming material containing a black pigment was applied to the surface of the substrate body on the emission side (the surface opposite to the surface on which the microlenses are formed) using a roll coater (for light-shielding film formation). Material application process). As the light-shielding film forming material, a mixture containing 10 wt% black pigment, 20 wt% damar resin, and 70 wt% xylene (liquid medium) was used.

Thereafter, xylene was removed from the light-shielding film forming material applied to the substrate body to form a film that covers the entire emission side of the substrate body. The average thickness of the formed film was 5 μm.
Next, the substrate with recesses was removed from the substrate body provided with the light-shielding film forming material.
Next, a laser beam in the vertical direction was irradiated from the surface of the substrate body on which the microlens was formed to the incident-side surface of the substrate body (opening forming step). As a result, the laser light is condensed by the microlens, and only the portion of the film near the focal point of the microlens is selectively removed, and the substrate is covered with a black matrix having a large number of openings. Thus obtained microlens substrate was obtained. The opening was substantially circular, and the average diameter was 24 μm. The formed black matrix had a thickness of 5 μm.

A transmissive screen as shown in FIG. 7 was obtained by assembling the microlens substrate manufactured as described above and the Fresnel lens portion manufactured by extrusion molding.
About each said Example and a comparative example, the average diameter of the 1st opening formed when manufacturing a board | substrate with a recessed part, the ratio with respect to the width | variety of the recessed part which should be formed, the diameter of a 2nd opening part , The length in the major axis direction, the length in the minor axis direction, the depth, the radius of curvature, the array pattern, the length in the major axis direction of the microlens that the manufactured microlens substrate has, the length in the minor axis direction Table 1 summarizes the height, radius of curvature, array pattern, and the like.

[Production of rear projector]
Rear projectors as shown in FIG. 8 were produced using the transmissive screens of the respective examples and comparative examples.
[Evaluation of etching uniformity]
In a bright room, white was displayed on the transmission screen of the rear projection TV of each of the examples and comparative examples. In this state, the screen perpendicular to the plane of the transmissive screen at the center, right, and upper right positions of the transmissive screen, and the screen from the direction perpendicular to the plane of the transmissive screen from the direction of 30 ° in the horizontal direction. The brightness (white luminance) was measured using a luminance meter. The white luminance in the vertical direction is a, the white luminance in the oblique 30 ° direction is b, and a / b is obtained at each of the center, right, and upper right positions of the transmission screen, and the maximum value of the three positions is a / b (max), the minimum value is a / b (min), the average of the three positions is a / b (ave), and the degree of etching variation B is determined by the following equation (I). It can be said that the lower the numerical value, the less the variation. At the time of evaluation, the difference in illuminance by the Fresnel lens was measured in advance, and it was excluded and evaluated. That is, the screen brightness = Fresnel + screen brightness ÷ Fresnel illuminance alone.
B = (a / b (max) −a / b (min)) / a / b (ave) × 100 (I)

[Evaluation of uneven color]
Sample images were displayed on the transmissive screens of the rear projectors of the examples and comparative examples. The displayed image was evaluated for color unevenness according to the following four criteria.
A: Color unevenness is not recognized at all.
○: Color unevenness is hardly recognized.
Δ: At least one of the color unevenness is slightly recognized.
X: At least one of color unevenness is remarkably recognized.
These results are summarized in Table 2.

  As apparent from Table 2, in the present invention, the variation in the shape of the concave portion and the microlens was small. In the present invention, an excellent image without color unevenness could be displayed. On the other hand, in the comparative example, a satisfactory result was not obtained.

  DESCRIPTION OF SYMBOLS 1 ... Microlens board | substrate 2 ... Board | substrate main body 21 ... Microlens 23 ... Resin material 25 ... 1st row | line 26 ... 2nd row 3 ... Black matrix (light shielding film) 31 ... Opening part 32 ... Film | membrane (material for light shielding film formation) 4 ... Mask forming film 5 ... Fresnel lens portion 51 ... Fresnel lens 6 ... Substrate with concave portion 612 ... Center 61 ... Concave portion 61 '... Initial concave portion 7 ... Substrate 8 ... Mask 81 ... First opening 82 ... Second opening 89 ... Back surface protective film 9, 9 '... Adhesive 11 ... Flat plate 10 ... Transmission type screen 20 ... Spacer 300 ... Rear projector 310 ... Projection optical unit 320 ... Light guide mirror 340 ... Housing

Claims (7)

A method for manufacturing a screen having a microlens,
Obtaining a substrate with a recess having a recess;
Obtaining the shape of the microlens provided in the screen based on the shape of the recess of the substrate with the recess;
Have
The step of obtaining the substrate with recesses includes:
A mask forming step of forming a mask having a plurality of first openings on the substrate;
Etching the substrate through the first opening to form an initial recess; and
An opening area expanding step for expanding the opening area of the first opening and forming the second opening by removing a portion of the mask corresponding to the initial recess along the peripheral edge of the initial recess. When,
A second etching step of etching the substrate through the second opening;
Have
In the opening area expanding step, a part corresponding to the initial concave portion of the mask is removed along a peripheral edge portion of the initial concave portion using an adhesive body having adhesiveness. The method for manufacturing a screen according to claim 1, wherein the mask has an average thickness of 5 to 500 nm. The mask and configured layer with chromium, primarily screen manufacturing method according to claim 1 or 2, which has been composed of a laminate having a formed layer in chromium oxide. The first opening, the screen manufacturing method according to any one of claims 1 to 3 and is formed by laser processing. The average diameter of the first opening, the screen manufacturing method according to any one of claims 1 to 4 is 0.8～20Myuemu. In the etching process, a screen manufacturing method according to any one of claims 1 to 5 is applied using an etching solution containing ammonium fluoride, and an acid. The step of obtaining the shape of the microlens
A step of applying a fluid resin material to the surface of the substrate with recesses on which the recesses are formed, and pressing the resin material with a flat plate;
A step of Ru solidifying the resin material,
A step except taking the substrate with concave portions and the flat plate,
A method for manufacturing a screen according to any one of claims 1 to 6 .

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