JP2007178674A - Lens sheet and method for producing lens sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lens sheet having excellent contrast performance and appearance without depending on the size of the pitch in each lens provided therein, to provide a back projection screen, and to provide a method for producing the lens sheet. <P>SOLUTION: The lens sheet is equipped with: lens lines 12 in which incident light is condensed to a horizontal direction and a vertical direction; and a light shielding layer 17 formed at a light emission side from the lens lines 12. Opening parts through which the incident light passed through the lens lines 12 can pass are formed at the light shielding layer 17, and the opening parts 18 are equipped with: incident light passing parts P4 corresponding to the shape through which the incident light passes; and a connecting part P3 of connecting the adjoining ones among the incident light passing parts P4 to a prescribed direction. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a lens sheet and a method for manufacturing the lens sheet, and more particularly to a rear projection screen on which the lens sheet is mounted.

In recent years, projection TVs equipped with an optical engine such as a liquid crystal device and a digital micro device have been rapidly spread. This projection TV is equipped with a transmission screen for observing images.
The transmission screen generally includes a Fresnel lens sheet and a lenticular lens sheet. The Fresnel lens sheet is for narrowing the image light from the rear projection type projector within a certain angle range, and is provided on the light source side. The lenticular lens sheet has a function of expanding the image light that has passed through the Fresnel lens sheet to an appropriate angle range.

FIG. 5 is a cross-sectional view showing a configuration of a conventional lenticular lens sheet. As shown in the figure, the lenticular lens sheet 30 includes a lens portion 32, a transparent support 33, a light shielding layer 37, a diffusion layer 35, and the like.
The incident surface of the lens unit 32 is composed of a plurality of lens rows made of convex lenses. In the example of FIG. 5, incident light is condensed in the lens medium and then diffused in the horizontal direction.

In recent years, the number of pixels of projectors is increasing in order to achieve high definition of video image quality. Along with this, a fine pitch is required for the pitch of the lenses (P in FIG. 5) provided in the lenticular lens sheet. Specifically, the pitch of the lens is generally around 0.7 [mm], whereas the fine pitch is 0.3 [mm] or less, more preferably 0.15 [mm] or less. Is required.
As shown in FIG. 5, the light shielding layer 37 is provided on the exit surface side of the transparent support 33 and at a non-passing position of image light as incident light. It plays a role of improving the contrast by absorbing external light and blocking ghost light caused by reflection and refraction which are not intended.

As a method for forming the light shielding layer 37, a method using an ultraviolet photosensitive resin film is known (Patent Document 1). This technology utilizes the difference in the presence or absence of adhesiveness between the exposed and unexposed areas of the photosensitive resin, and the adhesive resin part of the photosensitive resin layer formed on the back surface by exposure from the lens part side. In addition, a light-shielding pattern is formed by transferring the black transfer layer from the transfer paper.
As another method for forming the light shielding layer 37, a technique using a difference in surface free energy between an exposed portion and an unexposed portion is disclosed (Patent Document 2).

As shown in FIG. 5, the diffusion layer 35 is provided on the light exit surface side of the light shielding layer 37. The diffusion layer 35 has a role of diffusing in a direction (for example, the vertical direction) other than the direction (for example, the horizontal direction) in which the image light is condensed after being condensed by the lens 32.
The diffusion layer 35 has a problem that a light scattering loss occurs and a problem that external light is reflected to the viewer side and the external light contrast is deteriorated.

In order to solve these problems, a method of diffusing light in a horizontal direction and a vertical direction in a lenticular lens sheet has been proposed (Patent Document 3). FIG. 6 shows the structure of the lens disclosed in the publication. As shown in the figure, the lenticular lens sheet 40 includes a lens portion 42 in which unit lenses each having a substantially spherical portion are arranged on a plane, a lattice-shaped light shielding layer 47, and the like.
According to this lens, incident light can be diffused after condensing light in the horizontal and vertical directions with one unit lens. Further, the contrast can be improved by designing the image light to be collected in the lattice-shaped openings 48 (light passage portions) provided in the light shielding layer.

  However, the conventional lenticular lens sheet has the following problems. The technique disclosed in Patent Document 1 selectively forms a light-shielding layer using the adhesion between the transfer paper and the black layer, and the difference in adhesiveness between the exposed portion and the unexposed portion of the adhesive layer with respect to the black layer. It is. At this time, since the black layer is sheared at the boundary between the exposed portion and the unexposed portion, the adhesion force between the transfer paper and the black layer and the adhesive force to the black layer of the unexposed portion are necessary for shearing the black layer. Must be exceeded.

  Generally, since the thickness of the light-shielding layer required for the transmissive screen is 1 [μm] to 10 [μm], when the lens pitch is relatively large (when exceeding 0.3 [mm]), Since the force required for shearing the black layer is sufficiently small with respect to the adhesion between the transfer paper and the black layer in the exposed area for each pitch and the adhesive force to the black layer in the unexposed area, there are relatively few problems.

  However, when the pitch of the lens is 0.3 [mm] or less, the adhesion between the transfer paper and the black layer in the exposed portion in one pitch unit and the adhesive force to the black layer in the unexposed portion are reduced. Since the force necessary for shearing becomes relatively large, the influence of the force necessary for shearing the black layer cannot be ignored.

  The same problem can occur in the technique disclosed in Patent Document 2 described above. That is, even when the difference in surface free energy is used, the same problem arises due to the relationship between the surface tension of the colored paint and the ease of wetting of the colored paint on the lens sheet exit surface.

Most ideally, the light shielding layer has an opening shape only in the passage portion of the image light in order to improve the contrast. However, in practice, it has been difficult to accurately open the image light passage portion. In particular, the problem of appearance defects due to poor opening formation at the portion that should be opened has become serious as fine pitches are made. In particular, in the case of having a lattice-shaped opening as shown in FIG. 6 (the above-mentioned Patent Document 3) and having a fine pitch, since the opening is in the form of a dot, the formation of the opening is poor. As a result, the appearance defect problem has become more serious.
JP 2001-113538 A Japanese Patent Laid-Open No. 2003-075608 JP-A-62-157023

  The present invention has been made in view of the above problems, and a lens sheet, a rear projection screen, and a lens having excellent contrast performance and appearance regardless of the pitch of the lenses provided in the lens sheet. It aims at providing the manufacturing method of a sheet | seat.

  A lens sheet according to the present invention includes a plurality of lens units each collecting incident light in first and second directions, and a light shielding layer formed on the light exit side from the plurality of lens units. The light shielding layer is formed with an opening through which the incident light that has passed through the lens unit can pass, and the opening passes through incident light corresponding to a shape through which the incident light passes. Part and the connection part which connects what adjoins among the said incident light passage parts in a predetermined direction.

  In such a configuration, since the opening portion of the light shielding layer is formed by the incident light passage portion and the connecting portion that allows the incident light passage portion to pass in a predetermined direction, it is possible to prevent the formation of an opening portion. For example, when a black layer is transferred to a photosensitive adhesive layer, which will be described later, the untransferred areas are connected in a predetermined direction so that the transfer can be easily performed. In addition, when a light-shielding photocurable resin film, which will be described later, is used, when the cured part is peeled off, the peeled part is connected in a predetermined direction so that it is easily peeled off while preventing defective opening. be able to. As a result, even when the lens pitch is made fine, a light shielding layer having a desired opening can be obtained, and a lens sheet with excellent contrast performance can be provided.

  Further, the average value of the minimum values of the opening widths substantially orthogonal to the connecting direction of the opening portions of the connecting portions is 5% or more of the maximum value of the opening widths substantially orthogonal to the connecting directions of the incident light passage portions, It is preferable to set it to 80 [%] or less. By doing so, it is possible to prevent a poor opening formation such as a point defect while suppressing a decrease in contrast due to the formation of the opening other than the light passage portion. From the viewpoint of more effectively suppressing the decrease in contrast, the average value of the opening width of the connecting portion is set to 60 [%] or less, more preferably 50 [%] or less of the maximum value of the opening width of the light passing portion. Is preferred.

  Preferably, the plurality of lens units are arranged in a matrix and are configured by a plurality of microlenses that are convex on the light incident side on which the incident light is incident.

  A rear projection screen according to the present invention includes a Fresnel lens sheet that narrows the light emitted from the rear projection projector so as to fall within a certain angle range, the lens sheet as described above, and the exit surface of the lens sheet. And a front sheet provided on the side.

  The method for manufacturing a lens sheet according to the present invention is a method for manufacturing the lens sheet as described above, wherein the step of forming the light shielding layer includes the step of forming a photosensitive material layer on the light emitting surface side of the lens sheet. Irradiating light from the incident surface side of the lens sheet to form a photosensitive portion corresponding to the lens pattern on the photosensitive material layer, and a connecting portion so that adjacent ones of the photosensitive portions are connected to each other And a step of irradiating with light, and an unexposed portion of the photosensitive material layer may be used as the light shielding layer.

  In addition, the step of irradiating the connection part with light can be performed using a light source having a different diffusivity and / or parallelism from a light source that forms the light passage part in the connection direction.

  Furthermore, as a suitable example of the photosensitive material layer, a photosensitive adhesive layer or a photocurable composition layer can be used.

  Furthermore, in the method for producing a lens sheet according to the present invention, the photosensitive material layer in the case where the photocurable composition layer is used has the first composition and the surface free energy lower than that of the first composition. 2 is a photocurable composition layer comprising the composition of No. 2, wherein the photocurable composition layer is in contact with a medium having a surface free energy lower than that of the second composition. The photocurable composition layer is irradiated with light from the side, the photocurable composition layer in the condensing part by the lens pattern is irradiated with light, and the photocurable composition in the condensing part by the lens pattern Curing the composition layer; and the photocurable composition layer from the photocurable composition layer side in a state where the photocurable composition layer is in contact with a medium having a higher surface free energy than the first composition. The composition layer is irradiated with light, and the non-condensing part other than the condensing part A step of curing the curable composition, placing a colored material photocurable composition layer, in which and a step of forming a light-shielding pattern corresponding to the non-condensing portion.

  According to the present invention, there is an excellent effect that it is possible to provide a lens sheet and a rear projection screen with excellent contrast performance regardless of the size of the lens pitch.

Hereinafter, an example of an embodiment of a lens sheet to which the present invention is applied will be described.
FIG. 1 is a perspective view showing a configuration of a main part of a lens sheet according to the present embodiment. As shown in the figure, the lens sheet includes a lens layer 14 including a lens array 12 that condenses incident light in first and second directions, a light shielding layer 17, and the like. Hereinafter, regarding the lens sheet, a configuration that does not include the light shielding layer 17 is referred to as a lens sheet A (reference numeral 10 in the figure), and a lens sheet A that is provided with the light shielding layer 17 is referred to as a lens sheet B (reference numeral 11 in the figure).

On the light incident surface of the lens sheet A, substantially spherical microlenses are arranged.
The lens array 12 is composed of a plurality of lens arrays that are formed on the front side (incident side) as viewed from the light incident surface side and that act on the side where incident projection light is collected in the lens medium. . Each lens is arranged in the horizontal and vertical directions. That is, the lenses are arranged in a matrix.
The lens array 12 can condense incident light in the lens medium and then diffuse it horizontally, vertically and obliquely on the exit surface.

In the lens array 12, the horizontal pitch P1 and the vertical pitch P2 may be different. For example, when the lens array 12 is a part of a substantially sphere, the viewing angle in the horizontal direction can be further increased by setting P1> P2.
The lens array 12 may have a different curvature in the horizontal direction and the curvature in the vertical direction. For example, the horizontal viewing angle can be increased by increasing the horizontal curvature.

  The light shielding layer 17 is provided on the exit surface of the lens sheet A. FIG. 2 is a partially enlarged view of such a light shielding layer 17. As shown in the figure, the light shielding layer 17 has an opening connected in the vertical direction in the figure. The opening allows the image light that has passed through the lens array 12 to pass therethrough, and the light passing portion P4 corresponding to the passage shape of the image light and the connecting portion that connects the light passing portion P4 in the vertical direction. P3.

  The light shielding layer pattern of the lens sheet according to the present embodiment has a slightly reduced contrast area in theory because the area of the light shielding layer pattern is slightly smaller than the light shielding layer pattern on the lattice as shown in FIG. Will be reduced. However, when the openings are connected in a predetermined direction, it is possible to manufacture a screen that has better contrast performance than the configuration of FIG. 5 and fewer appearance defects than the configuration of FIG.

  3 and 4 are partially enlarged views in the vicinity of the opening 18. As shown in FIG. 3, the average value of the minimum values of the opening width P6 of the connecting portion P3 in the width substantially orthogonal to the connecting direction (hereinafter simply referred to as “opening width”) is the opening width P5 of the light passing portion P4. The maximum value is 5 [%] or more and 80 [%] or less. By doing so, it is possible to prevent a poor opening formation such as a point defect while suppressing a decrease in contrast due to the formation of the opening other than the light passage portion P4.

  From the viewpoint of more effectively suppressing the decrease in contrast, the average width of the minimum value of the opening width P6 of the connecting portion P3 is 60% or less of the maximum value of the opening width P5 of the light passing portion P4, more preferably 50 [%] Or less is preferable. If it is less than 5%, the effects of the present invention may not be exhibited. For example, in FIG. 3, when the maximum value of the opening width P5 of the light passage portion P4 is 30 [μm], 5 [%] is 1.5 [μm], which may be very difficult to process. Because there is. In addition, the preferable range of the average value of the minimum value of the opening width P6 of the connection part P3 is 1.5 [μm] or more.

  Also, as shown in FIG. 4, the area S2 of the region surrounded by the line segment connecting the ends of the maximum width P5 of the adjacent light passing portions P4 and having no opening is formed. Particularly preferably, it is 50 [%] or more of the region S1 surrounded by the maximum width P3 of the adjacent light passing part P4. By doing so, it is possible to more effectively suppress a reduction in contrast due to the formation of the opening other than the light passage portion P4.

  In the present embodiment, the example in which the connecting direction of the openings is formed in the vertical direction in the figure has been described. However, the present invention is not limited to this and may be a horizontal direction or an arbitrary direction. In the present embodiment, an example in which the lines are connected in the vertical direction has been described. However, the present invention is not limited to this, and a configuration in which a plurality of connected blocks are provided may be employed.

The lens sheet of the present invention can be used as a rear projection screen together with a Fresnel lens sheet. Besides this, it may be applied to the viewing side of various displays in order to improve the external light contrast.
Further, a diffusion layer is provided on the exit side of the light shielding layer 17, and various types such as HC (hard coat), AG (antiglare), AR (antireflection), AS (antistatic) are provided on the outermost surface of the exit. A functional film may be provided.

Then, the manufacturing method of the lens sheet concerning this embodiment is demonstrated.
First, the lens sheet A is produced. For example, the base resin can be melt-extruded with a T-die, and a minute lens can be formed on one side with a mold roll having a shape opposite to that of the lens array 12.
Further, instead of the melt extrusion molding described above, the lens may be molded by press molding or injection molding. You may perform lens sheet shaping | molding with a base material sheet and ultraviolet curable resin.
Further, a photosensitive adhesive layer is formed on the light exit surface of the lens sheet A integrated in the above-described process. And the light emission part 18 and the connection part P3 are exposed. At this time, the following method can be used as a method for selectively exposing the light emitting portion 18 and the connecting portion P3.

The diffusivity of the anisotropic diffusion sheet is designed so that the light is exposed by an anisotropic diffusion sheet combining a parallel light beam and a lens sheet, for example, so that a part of the light beam is emitted not only in the vicinity of the light emitting part 18 but also in the connecting part P3. ·adjust.
Here, the exposed portion refers to a relatively high-density exposed portion, and the unexposed portion refers to a relatively low-density exposed portion. Therefore, the unexposed portion is not limited to being not exposed at all.
Next, a black transfer sheet is laminated on the surface of the selectively exposed photosensitive adhesive layer, and then peeled off to transfer the black layer only to the unexposed portion of the photosensitive adhesive layer. Through such steps, the light shielding layer 17 is formed.

In the above embodiment, the connecting portion P3 is formed by using exposure light sources having different vertical and horizontal diffusivities and parallelism, but is not limited thereto. For example, the lens may be designed so that transmitted light is partially diffused in the direction in which it is desired to be connected. In this case, the opening can be formed by exposing the light shielding layer 17 from the image light incident surface side of the lenticular lens using a light source having a condensing or diffusing characteristic equivalent to that of the image light.
Further, the light emitting part 18 and the connecting part P3 may be exposed by changing the intensity of the light beam (for example, by adjusting the power and exposure time) and the angle of incidence.

Furthermore, as another example, a method of providing anisotropy in the affinity between the paint and the lenticular lens exit surface by applying centrifugal force, gravity, etc. when applying the colored paint, Examples thereof include a method of providing anisotropy to the shear force.
Of course, the exposure of the light emitting part 18 and the connecting part P3 is not limited to these, and the above methods may be combined and exposed simultaneously or separately.

  Moreover, although the example which forms the light shielding layer 17 using a photosensitive adhesive layer was demonstrated in this embodiment, it is not limited to this. For example, you may use the method of forming a light shielding layer with the light-shielding photocurable resin film (resin hardened | cured by light irradiation). As a method for forming a light shielding layer using a light-shielding photocurable resin film, for example, the light shielding layer can be formed by the following method.

First, a film coated with a light-shielding photocurable resin is bonded to the light exit surface of the second lens layer 15 of the lens sheet A, and ultraviolet rays are irradiated from the incident surface side of the lens sheet. As a result, the light-blocking photo-curing resin in the ultraviolet condensing part is cured. Thereafter, the film is peeled off. The light-blocking photo-curing resin in the ultraviolet non-condensing part remains uncured on the exit surface of the second lens layer 15, and the light-blocking photo-curing resin in the ultraviolet condensing part is peeled off while being fixed to the film. Is done.
Subsequently, the uncured light-blocking light-curing resin of the non-condensing portion is irradiated with radiation from the exit surface side of the lens sheet. Thereby, the uncured light-shielding curable resin is cured to form a light-shielding layer.

  Further, the light shielding layer 17 may be formed using the difference in surface free energy between the exposed portion and the unexposed portion. For example, 100 parts by mass of the photocurable resin composition (a) having a surface free energy of 30 [mN / m] or more and a surface free energy of 25 [mN / m on the light emitting surface of the second lens layer 15. A layer of the composition comprising 0.01 to 10 parts by mass of the following compound (b) is provided. Next, exposure light is irradiated from the lens part side in contact with a medium (for example, air) having a surface free energy lower than that of the compound (b). The irradiated light is condensed by the lens, and only the photocurable composition (A) in the condensing part is selectively cured. In this way, it is possible to obtain a lens sheet in which the surface energy of the light collecting portion is 25 [mN / m] or less.

By irradiating light from the exit surface side of the lens sheet in a state where the obtained lens sheet is in contact with a medium (for example, water) having a surface free energy higher than that of the photocurable resin composition (a), uncured Only the photocurable composition (A) is cured. The wettability of various liquids is different on surfaces having different surface free energies, and in the case of commonly used solvents and paints, the surface having a higher surface free energy is more easily wetted than the surface having a lower surface free energy. Therefore, the surface-modified lens sheet is more easily wetted by various liquids in the non-light-collecting part than in the light-collecting part.
Using this property, by applying a colored paint to the surface-modified lens sheet, it is possible to form a light-shielding pattern in which the colored paint is attached only to the non-light-collecting portion. In addition, a known method for forming a light shielding layer can be used as appropriate.

Next, a front sheet 19 can be laminated on the light exit surface side of the light shielding layer 17. Lamination can be realized by adhesion with a radiation curable resin or adhesion with an adhesive material.
Furthermore, the functional film 20 may be laminated on the surface of the front sheet 19. Specifically, the functional film 20 is directly coated on the front sheet 19 or a film coated with the functional film 20 is laminated. With such a manufacturing method, a rear projection screen can be manufactured.

According to the lens sheet according to the present embodiment, the opening portion of the light shielding layer is configured by the incident light passage portion P4 and the connecting portion P3 that allows the incident light passage portion P4 to pass in a predetermined direction. Can be prevented. For example, when the black layer is transferred to the photosensitive adhesive layer, the untransferred areas are connected in a predetermined direction so that the transfer can be easily performed.
In addition, when the light-shielding photocurable resin film is used, when the cured part is peeled off, the peeled part is connected in a predetermined direction so that it can be easily peeled off while preventing a defective opening. Can do. As a result, it was possible to provide a lens sheet excellent in contrast performance while suppressing appearance defects.

  The configuration of the lens unit of the present invention is not limited to that of the above embodiment. The arrangement of the lens units is not limited to a square arrangement, and may be a delta (rhombus) arrangement. The lens unit may be a hexagon or a hexagonal array.

The perspective view which shows a part of structure of the rear projection type screen concerning this embodiment. The elements on larger scale of the light shielding layer concerning this embodiment. The elements on larger scale of the light shielding layer concerning this embodiment. The elements on larger scale of the light shielding layer concerning this embodiment. The perspective view which shows a part of structure of the rear projection type screen concerning a prior art example. The perspective view which shows a part of structure of the rear projection type screen concerning a prior art example.

Explanation of symbols

10 ... lens sheet A, 11 ... lens sheet B, 12 ... lens array, 14 ... lens layer,
17 ... light shielding layer, 18 ... opening

Claims (8)

A plurality of lens units each collecting incident light in first and second directions;
A lens sheet provided with a light shielding layer formed on the light emitting side from the plurality of lens units,
The light shielding layer is formed with an opening through which the incident light having passed through the lens unit can pass. The opening includes an incident light passage corresponding to a shape through which the incident light passes, and the incident light. A lens sheet provided with the connection part which connects what adjoins among light passage parts in a predetermined direction.   The average value of the minimum values of the opening widths substantially orthogonal to the connecting direction of the opening portions of the connecting portions is not less than 5 [%] of the maximum value of the opening width substantially orthogonal to the connecting direction of the incident light passing portion, and 80 [ %] Or less. The lens sheet according to claim 1, wherein:   The lens sheet according to claim 1, wherein the plurality of lens units are arranged in a matrix and are configured by a plurality of microlenses that are convex on a light incident side on which the incident light is incident. A Fresnel lens sheet that narrows the light emitted from the rear projection projector so that it falls within a certain angle range;
The lens sheet according to any one of claims 1 to 3,
A rear projection screen comprising a front sheet provided on the exit surface side of the lens sheet. A method for producing a lens sheet according to any one of claims 1 to 3,
The step of forming the light shielding layer includes:
Forming a photosensitive material layer on the light exit surface side of the lens sheet;
Irradiating light from the incident surface side of the lens sheet to form a photosensitive portion corresponding to the lens pattern in the photosensitive material layer;
Irradiating the connecting portion with light so that adjacent ones of the photosensitive portions are connected,
A method for producing a lens sheet, wherein an unexposed portion of the photosensitive material layer is used as the light shielding layer. 6. The method of manufacturing a lens sheet according to claim 5, wherein the step of irradiating the connection part with light comprises:
A method for producing a lens sheet, wherein the light source is formed using a light source having a different diffusivity and / or parallelism from the light source that forms the light passage part in the connecting direction. It is a manufacturing method of the lens sheet of Claim 5 or 6,
The method for producing a lens sheet, wherein the photosensitive material layer is a photosensitive adhesive layer. A method for producing a lens sheet according to claim 5, 6 or 7,
The photosensitive material layer is a photocurable composition layer comprising a first composition and a second composition having a surface free energy lower than that of the first composition;
In a state where the photocurable composition layer is in contact with a medium having a surface free energy lower than that of the second composition, the photocurable composition layer is irradiated with light from the incident surface side of the lens sheet, Irradiating the photocurable composition layer in the condensing portion by the lens pattern with light, and curing the photocurable composition layer in the condensing portion by the lens pattern;
In a state where the photocurable composition layer is in contact with a medium having a surface free energy higher than that of the first composition, light is applied to the photocurable composition layer from the photocurable composition layer side, Curing the photocurable composition in a non-light-collecting part other than the light-collecting part;
And a step of disposing a coloring material on the photocurable composition layer and forming a light shielding pattern corresponding to the non-light-condensing portion.

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