JP2003302505A - Lens array sheet, master for the lens array sheet, method for manufacturing the master for the lens array sheet, metal mold for the lens array sheet, method for manufacturing the metal mold for the lens array sheet, screen sheet, and rear projection system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lens array sheet, a master for the lens array sheet, a manufacturing method for the master for the lens array sheet, a metal mold for the lens array sheet, a manufacturing method for the metal mold for the lens array sheet, a screen sheet, and a rear projection system so that the screen sheet can be manufactured which can secure a wide field angle within both necessary horizontal and vertical ranges. <P>SOLUTION: The lens array sheet which has a plurality of microlenses arranged on at least one surface is characterized in that intervals of a plurality of convex lenses 2 are different from intervals of the centers of the lenses 2. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens array sheet, a lens array sheet master, a method for manufacturing a lens array sheet master, a lens array sheet mold, a lens array sheet mold manufacturing method, a screen sheet,
It relates to the rear projection system.

[0002]

2. Description of the Related Art In recent years, a rear projection type image display device (rear projection system) has been attracting attention as a means for displaying a relatively large screen with a compact device configuration. The device is configured to display a large-screen color image by magnifying and projecting an image formed by liquid crystal or the like having a size smaller than the actual screen by an optical system.

When displaying an image, since the screen is a large screen, a large angle is formed with a single viewer, and a wide viewing angle is required so that multiple viewers can view the image. In order to obtain a wide viewing angle on the screen, (1) a method of securing a viewing angle by dispersing a substance having a light scattering effect in the screen and widely scattering incident light, (2) vertically By providing a striped lenticular lens array with a structure in which long, semi-cylindrical lenses are adjacent to each other in the horizontal direction, the horizontal viewing angle is controlled and the light scattering effect is achieved in the lens array or in a separate member. A method of dispersing a certain substance to secure a vertical viewing angle and the like are mainly practiced (see, for example, JP 2000-137294 A).

However, in the above-mentioned configuration (1), since the expansion of the viewing angle in both the vertical direction and the horizontal direction depends on the scattering of the light-scattering substance in the screen, it is attempted to expand the viewing angle. Since it is necessary to increase the concentration of the light scattering substance in the screen, there is a problem that light is attenuated in the screen and an image obtained on the screen becomes dark. In the configuration of (2), the viewing angle in the horizontal direction is controlled by the lens, but there is the same problem as in (1) in the vertical direction.

In order to solve such a problem, Japanese Unexamined Patent Application Publication No.
In Japanese Patent Application Laid-Open No. 00-321675, it is proposed that each lens element of the microlens array sheet forming the screen has different curvatures in the horizontal direction and the vertical direction to control the respective visual fields.

[0006]

[Patent Document 1] Japanese Unexamined Patent Application Publication No.
In the prior art disclosed in Japanese Patent Publication No. 000-321675, since the shape of each lens element is the same in the same screen sheet, the visual field characteristics are the same at any place of the screen. When the height is equal to or more than the height of the human body, the viewing angle is further widened from that position, and there is a problem that the amount of light reaching the substantially necessary area is reduced. In addition, there is no description about a method of manufacturing a mold that determines the shape of the lens, which is most important in manufacturing, and it is difficult to actually manufacture the lens.

Therefore, the present invention has been made to solve the above-mentioned problems, and a lens is provided for manufacturing a screen sheet which can secure a sufficiently wide viewing angle within a required range both horizontally and vertically. An object of the present invention is to provide an array sheet, a lens array sheet master, a lens array sheet master manufacturing method, a lens array sheet mold, a lens array sheet mold manufacturing method, a screen sheet, and a rear projection system.

[0008]

In order to solve the above-mentioned problems, in the invention according to claim 1, a plurality of convex lenses are provided in a lens array sheet in which a plurality of fine lenses are arranged on at least one surface. The most main feature is a lens array sheet configured so that the distance between the lens and the center of the lens is different.

According to a second aspect of the present invention, in a lens array sheet in which a plurality of fine lenses are arranged on at least one surface, the intervals between the plurality of lens centers are even in the horizontal direction and are vertical. In the above, the main feature is a lens array sheet configured differently.

According to a third aspect of the invention, a first metal layer constituting at least the surface of the base material, an insulating layer covering the first metal layer and having minute openings formed at predetermined intervals,
The lens array sheet master is characterized by a second metal layer having a convex shape that is connected to the second metal layer through the opening of the insulating layer and a third metal layer that covers the second metal layer.

The invention according to claim 4 is characterized by the lens array sheet master according to claim 3, wherein the main metals of the second and third metal layers are the same material.

In a fifth aspect of the present invention, a step of preparing a base material on which at least a first metal layer is formed, and a first insulating layer having minute openings at predetermined intervals on the base material are provided. The step of forming and the opening of the area including the minute openings on the base material on which the first insulating layer is formed and corresponding to the size of the lens at different intervals, Forming a thicker second insulating layer;
The step of depositing the second metal layer from the first metal layer by electrodeposition of the first plating bath using the base material on which the insulating layer and the second insulating layer are formed as a cathode, and then the second plating The main feature of the method for producing a master for a lens array sheet includes a step of depositing a third metal layer by electrodeposition of a bath and a step of removing the second insulating layer.

In the invention according to claim 6, as the step of depositing the third metal layer, a bright plating bath capable of depositing the same metal as the first plating bath is used in the second plating bath. The main feature is the method for producing a master for a lens array sheet described in item 5.

According to the invention of claim 7, claim 3 or 4
The main feature is a lens array sheet mold having an inverted shape of the described lens array sheet master.

In the invention according to claim 8, a step of preparing at least a master for a lens array sheet, a step of conducting a conductive treatment on a region formed in at least a convex shape on a surface on which the convex shape is formed, and a conductive treatment are performed. A step of releasing the surface, a step of depositing a metal to be a mold in a plating bath by using the lens array sheet master as a cathode, and a step of separating the master and the mold with a release layer as an interface. The main feature is a method for manufacturing a lens array sheet mold, which comprises the steps of:

The invention according to claim 9 is characterized mainly in a screen sheet constituted by using the lens array sheet according to claim 1 or 2.

A tenth aspect of the present invention is mainly characterized in that the rear projection system is configured by using the screen sheet according to the ninth aspect.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a diagram showing a state in which an embodiment of a lens array sheet according to the present invention is viewed from the upper surface of a lens, and FIG. 2 is a view taken along the line II-II in FIG.

In FIG. 1, a plurality of convex lenses 2 are arranged in a matrix on a substrate 1 at a pitch P ^L , and the center of the convex lenses 2 coincides with the center of the lens in the central row in the drawing and the lens pitch in the lateral direction is the lens pitch. They are the same, and the pitch P ^C is smaller than P ^L in the vertical direction. The center lens 2a of the convex lenses 2 has a vertically symmetrical shape, the lens 2b above the center has its optical axis tilted downward, and the lens 2c below the center, on the other hand, has its optical axis. The axis is tilted upward, and the tendency becomes larger as it goes away from the center. When vertical light is made incident on the lens array sheet having such a shape, the light that has passed through the central lens 2a spreads vertically evenly. On the other hand, the light passing through the lens 2b above the center spreads broader downward than the upper side, and the light passing through the lens 2c below the center spreads upward rather than the lower side. As a result, as shown in FIG. 2, the light from any part of the lens array sheet can be applied to the same area limited behind the light. It should be noted that this region can be changed to a desired position by changing the size of the lenses 2a, 2b and 2c and the shift between the lens center and the optical center. Further, although there is a large gap between the lens elements in the figure, this can be made narrower as appropriate.

By forming a screen (screen sheet) using such a lens array sheet,
Since light having a large laterally symmetrical spread is emitted in the horizontal direction, a wide viewing angle can be obtained. Also, although the field of view becomes narrower in the vertical direction than in the horizontal direction, when considering a screen that is viewed by multiple people, the viewers are positioned wider in the horizontal direction than the screen.
It can be used preferably. Further, in the vertical direction, there is no problem because it is about the difference between the line of sight of the viewer when standing or sitting. In addition, the upper end of the screen is at a height equal to or higher than the line of sight of the viewer, and the lower end is at a height equal to or lower than the line of sight of the viewer. It is not desirable to spread the lower light downward, and it causes unevenness in the brightness of the screen, which is not preferable. Therefore, with the screen sheet as described above, it is possible to obtain light distribution characteristics without wasting the light above and below the screen. Further, it is possible to provide a rear projection system capable of displaying a high quality image using a screen sheet.

Further, although the above-mentioned example describes the case where a uniform light distribution characteristic is given in the vertical direction from the center in the height direction of the screen, the lens center and the optical center coincide with each other depending on the scene where the screen is installed. It is also possible to obtain a lens array sheet and a screen having a light distribution characteristic that is directed upward or downward by appropriately changing the place to be turned up and down.

Next, FIG. 3 is a view showing another embodiment of the lens array sheet according to the present invention as viewed from the top of the lens. FIG. 3 shows an example in which the lens pitch and the lens center pitch are changed in both the horizontal and vertical directions. With such a shape, the light distribution characteristic can be controlled in both horizontal and vertical directions.

Next, FIG. 4 is a view showing a state in which another embodiment of the lens array sheet according to the present invention is viewed from the upper surface of the lens. FIG. 4 shows an example in which the lens 3 has a hexagonal outer shape and is densely arranged. With such an arrangement, the pitch between lens elements can be reduced. It is known that moire may occur due to a combination of regular arrangements, but this is reduced by making one pitch sufficiently smaller than the other pitch. Therefore, it is possible to reduce moire by adopting the configuration as in this example.

Next, FIG. 5 is a step diagram showing a method for producing a master and a die for producing the lens array sheet according to the present invention. FIG. 5 shows the method of manufacturing the master and the mold.
Will be described. First, the substrate 5 having the first metal layer 4 is prepared. Here, as the substrate 5, 10 mm of electroless nickel plating (metal layer) is formed on a glass substrate having a thickness of 1 mm.
00 to 10000Å was used. If the thickness of the electroless nickel plating is less than this, defects such as pinholes may occur, and if it is more than this, the stress of the film becomes large and peeling occurs at the interface with the substrate 5. there is a possibility. The substrate 5 may be a member in which the metal film 4 is formed on a non-metal substrate as in this example, or may be made of metal as a whole.

Next, the first insulating layer 6 is formed on the entire surface of the substrate 5.
As a positive photoresist layer having a thickness of 1 μm, a portion where the center as a lens is to be formed is exposed through a photomask and then developed, and the resist in the exposed portion is removed to obtain a φ4 μm diameter film. The first metal layer 4 was exposed. Here, the method for forming the first insulating layer 6 and the opening is not limited to the lithography process using a photoresist, but a method such as screen printing or a method of directly removing the other material by laser irradiation after forming other materials is used. You can Further, the diameter for exposing the first metal layer 4 as an opening is 1/5 or less, more preferably 1/10 or less, of the lens diameter to be manufactured in order to reduce the influence on the lens shape.

Subsequently, a dry film resist layer having a thickness of 50 μm is formed thereon as a second insulating layer 7, exposed through a photomask, and then developed to form an opening of φ40 μm corresponding to a place where a lens is to be formed. The exposed portion of the first insulating layer 6 and the first metal layer 4 formed therein is exposed. The method for forming the second insulating layer 7 is the same as the first insulating layer 6
It can also be formed by other methods similar to. In this way, the portion corresponding to the lens outer shape is the second insulating layer 7
The opening corresponding to the center of the lens is formed as the opening of the first insulating layer 6. At this time, since the lens outer shape interval P ^L and the lens center interval P ^C are different, the appearance is as shown in FIG.

Further, this substrate 5 is electroplated in nickel sulfamate using the first metal layer 4 as a cathode until the height of the lens center portion becomes 15 μm to form a second metal layer 8. Subsequently, using this substrate 5 as a cathode, electroplating is performed to a thickness of 5 μm in a bright nickel plating bath to form a third metal layer 9.

Next, a second dry film stripping solution is used.
A master is formed by removing the insulating layer.

Next, a nickel film of 1000 liters is formed by sputtering this master surface as a conductive treatment,
Subsequently, as a release treatment, UV light is irradiated on the surface of the nickel film in the presence of oxygen to form an oxide layer on the surface. Subsequently, nickel is deposited to 100 μm or more on the surface of the substrate 5 in nickel sulfamate using the substrate 5 as a cathode by electroplating. After that, the oxide layer formed by the above-mentioned peeling process is peeled from the master 10 with the interface as an interface, so that the mold 11 having an inverted shape of the master 10 is obtained.

A lens array sheet can be obtained by coating the mold 11 thus obtained with an ultraviolet curable resin, irradiating it with ultraviolet rays to cure it, and then peeling it off from the mold.

Alternatively, the lens array sheet can be obtained by pressing the heated die onto a thermoplastic film.

[0032]

As described above, according to the lens array sheet of the first aspect, since the lens interval and the lens center interval are different, the lens shape center and the optical axis center of the lens are different, and the light beam after the lens exits. The light distribution can be controlled by causing a deviation in the traveling direction.

According to the lens array sheet of claim 2,
Since the center of the lens is uniform in the horizontal direction and different in the vertical direction, the viewing angle is the same from any position in the horizontal direction, and the viewing angle is deviated according to the distance between the lens centers in the vertical direction. Can be controlled.

According to the lens array sheet master of the third aspect, since the surface can be made sufficiently smooth, a mold that is faithful to the master shape and is excellent in mold releasability from a mold obtained by copying. Obtainable. Further, a lens sheet having good optical characteristics can be obtained from this.

According to the lens array sheet master of the fourth aspect, since the main metals of the second and third metal layers are the same, the coefficient of thermal expansion can be maintained even when a temperature change occurs in the mold duplication process. The mold can be obtained without causing peeling at the interface of the metal layer due to a difference or the like.

According to the method for manufacturing a master for a lens array sheet of claim 5, the position of the center of the lens is determined by the opening of the first insulating layer, and the position of the entire lens is determined by the second insulating layer, and then the metal is used. Since it is produced by the layer deposition treatment, it is possible to properly produce a master in which a large number of lenses having different positional relationships between the lens center and the lenses are formed.

According to the method for producing a master for a lens array sheet of claim 6, since the gloss plating bath is used for depositing the third metal layer, a master having a smooth deposition surface can be produced.

According to the lens array sheet mold of the seventh aspect, since it has the inverted shape of the master according to the third and fourth aspects, the surface is smooth and the mold releasability after molding is excellent and obtained. The molded product also has good optical properties.

According to the method of manufacturing the lens array sheet mold of the eighth aspect, the method includes the step of forming the release layer on the surface of the master. Therefore, even if the opening for connecting the lens portion of the master and the substrate is small, the master The mold and the mold can be reliably separated.

According to the screen sheet of claim 9, since the lens array sheet of claim 1 or 2 is used,
The visual field characteristics can be controlled independently in the vertical direction and the horizontal direction, and can also be controlled in the plane, resulting in a screen with excellent visibility.

According to the rear projection system of claim 10, since the screen according to claim 9 is used,
It is possible to display a high-quality image with excellent visibility.

[Brief description of drawings]

FIG. 1 is a diagram showing a state in which an embodiment of a lens array sheet according to the present invention is viewed from the top surface of a lens.

FIG. 2 is a view taken along the line II-II in FIG.

FIG. 3 is a diagram showing a state in which another embodiment of the lens array sheet according to the present invention is viewed from the upper surface of the lens.

FIG. 4 is a diagram showing a state in which another embodiment of the lens array sheet according to the present invention is viewed from the upper surface of the lens.

FIG. 5 is a step diagram showing a method for producing a master and a mold for producing a lens array sheet according to the present invention.

[Explanation of symbols]

1 substrate 2 convex lens 2a Center lens 2b Lens above center 2c Lens below center 3 lenses 4 First metal layer 5 substrates 6 First insulating layer 7 Second insulating layer 8 Second metal layer 9 Third metal layer 10 masters (master for lens array sheet) 11 Mold (mold for lens array sheet)

   ─────────────────────────────────────────────────── ─── Continued front page    (54) [Title of Invention] Lens array sheet, master for lens array sheet, method for manufacturing master for lens array sheet,                     Mold for lens array sheet, manufacturing method for mold for lens array sheet, screen sheet, rear plate                     Projection system

Claims (10)

[Claims] 1. A lens array sheet having a plurality of fine lenses arranged on at least one surface thereof, wherein the intervals between the plurality of convex lenses and the intervals between the centers of the lenses are different from each other. Sheet. 2. A lens array sheet having a plurality of fine lenses arranged on at least one surface thereof, wherein the intervals between the centers of the plurality of lenses are uniform in the horizontal direction and different in the vertical direction. A lens array sheet characterized by the above. 3. A first metal layer forming at least the surface of a base material, an insulating layer covering the first metal layer and having minute openings formed at predetermined intervals, the first metal layer and the insulation. A lens array sheet master, comprising: a convex second metal layer connected through an opening of the layer; and a third metal layer covering the second metal layer. 4. The lens array sheet master according to claim 3, wherein the main metals of the second and third metal layers are the same material. 5. A step of preparing a base material having a first metal layer formed on at least a surface thereof, and a step of forming a first insulating layer having minute openings at predetermined intervals on the base material, 1
Second insulating layer including minute openings on the base material on which the insulating layer is formed and having openings in regions corresponding to the size of the lens at different intervals and thicker than the height of the lens master to be manufactured. And a step of depositing a second metal layer from the first metal layer by electrodeposition of a first plating bath using the base material on which the first insulation layer and the second insulation layer are formed as a cathode. And a step of subsequently depositing a third metal layer by electrodeposition of a second plating bath, and a step of removing the second insulating layer, the method for producing a master for a lens array sheet. 6. The step of depositing a third metal layer comprises:
The method for manufacturing a master for a lens array sheet according to claim 5, wherein a gloss plating bath capable of depositing the same metal as that of the first plating bath is used as the second plating bath. 7. A mold for a lens array sheet, which has an inverted shape of the master for a lens array sheet according to claim 3 or 4. 8. A step of preparing at least a master for a lens array sheet, a step of subjecting at least a region formed in a convex shape on a surface on which a convex shape is formed to a conductive treatment, and a release treatment to the surface subjected to the conductive treatment. A step of depositing a metal to be a mold in a plating bath by using the lens array sheet master as a cathode, and a step of peeling the master and the mold with the release layer as an interface. A method for manufacturing a die for a lens array sheet, which is characterized. 9. A screen sheet comprising the lens array sheet according to claim 1 or 2. 10. A rear projection system, comprising the screen sheet according to claim 9.