JP2002357869A - Microlens sheet, rear projection type screen using the same and display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a microlens sheet capable of controlling light diffusion not only in a horizontal direction, but also, in an outgoing direction by 360 deg. by the lens function of a single lens sheet, and where unit lens groups are arranged in parallel at a highly accurate pitch. SOLUTION: As for the microlens sheet provided with a microlens array part constituted by two-dimensionally arranging each unit lens in a nearly matrix state on at least one side of a substrate, the microlens array part is formed only on one side of the substrate, and the array part includes the unit lens having an aspherical curved surface, and the arrangement pitch of the unit lens is controlled to be <=200 μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microlens sheet effective for use in an image display screen for a rear projection type projection TV (hereinafter, referred to as a transmission type projection screen or a rear type projection screen).

[0002]

2. Description of the Related Art Transmissive projection screens are
Generally, it is constituted by a combination of a Fresnel lens sheet and a lenticular sheet.

[0003] The Fresnel lens sheet emits projection light (divergent from a small-diameter lens) from the projector to the lenticular sheet side as substantially parallel light due to the convex lens characteristic.

The lenticular sheet spreads the projected light, which has been made substantially parallel light by the Fresnel lens sheet, in the horizontal direction due to the characteristics of the cylindrical lenses arranged in the horizontal direction, and emits the display light to the observer side. I do.

Further, the rear projection screen spreads display light in the vertical direction, forms an image of projection light from the projector, and eliminates an unnecessary image called a scintillation caused by a small diameter lens of the projector. A light diffusion layer is conventionally formed for the purpose of, for example, reducing flicker. The light diffusion layer is formed on at least one of a lenticular sheet, a Fresnel lens sheet, and an outermost front plate functioning as a protective plate, and an appropriate method such as coating, laminating, or mixing is employed in forming the light diffusing layer. .

In recent years, instead of a three-tube (R, G, B) CRT type projector, a liquid crystal projector or a TI
(Texas Instruments), a registered trademark “DMD (Digital Micromirror Device) or DLP (Digital Light Processing)” is used as a single-tube projector based on a reflective light valve system. Display devices have become widespread, and there is a demand for a rear projection screen suitable for these new devices.

The present applicant has proposed a rear projection screen having a lenticular sheet as exemplified in JP-A-9-120101, JP-A-8-269546, and JP-A-10-83029. All of the embodiments relate to a lenticular sheet that has a cylindrical lens group arranged in a horizontal direction and is required to include a light diffusion layer having sufficient light diffusion characteristics in any of the inside thereof.

As described above, the control of the viewing angle (range) of the display light by the existing lenticular sheet can be controlled only in the horizontal direction by the lens function, and the control in the vertical direction depends on the light diffusion layer. Will be.

The effect of the viewing angle control by the lens function is high and dynamic, but the effect of the viewing angle control by the light diffusion layer is relatively low and gentle. Generally, the light diffusing layer is formed by dispersing and mixing light diffusing fine particles in a resin. The difference in the refractive index between the light diffusing fine particles and the resin, the particle size of the light diffusing fine particles (and the distribution thereof), or dispersion. Not only is it difficult to select a suitable combination of both, such as suitability, but also it is structurally difficult to control light diffusion only in the vertical direction, and it also affects light diffusion in the horizontal direction Is inevitable.

Further, increasing the light diffusivity requires excessive mixing of the light diffusing fine particles, so that the transmitted light is attenuated (reduced display luminance) and the cost is increased.

Attempts have been made to achieve both horizontal and vertical light diffusion by using the lens function. However, in addition to a lens sheet for controlling the horizontal light diffusion, the vertical light diffusion is also required. The method of adding a lens sheet for control makes it difficult to align both lenses when setting the screen, and increases costs due to an increase in members.

There is also a method of employing a lens sheet having a configuration in which light diffusibility can be controlled by a lens function in a direction other than horizontal, instead of a lenticular sheet, using a screen having a combination of a Fresnel lens sheet and a lenticular sheet. And Japanese Patent Application Laid-Open No. 2000-131506. The proposal according to the above publication is a lens sheet including a microlens array portion in which a microlens having an optically concave or convex rotationally symmetric shape, and a layer in which the shape is arranged in a rhombic shape, is provided on the emission surface side. A microlens sheet having a structure in which a diffusion sheet layer is disposed on the surface or a sheet layer containing a diffusing agent is provided inside the microlens array portion.

In the above-mentioned new device, a panel (a liquid crystal or a micromirror array) for defining a projection image is provided in accordance with an increase in the number of pixels in order to provide a high-resolution image, as typified by XGA. Higher definition is desired, and it is desired that the parallel pitch of the cylindrical lens group be also higher on the screen side.

In view of the above background, the present invention makes it possible to control not only the horizontal direction but also the light diffusion over 360 ° in the emission direction by using the lens function of one lens sheet.
A unit lens group suitable for manufacturing a rear projection screen composed of two lens sheets in combination with a Fresnel lens sheet without inviting a large amount of a light diffusing agent, and suitable for observation of high-resolution image quality. It is an object of the present invention to provide a microlens sheet arranged in parallel at a high definition pitch.

[0015]

According to the present invention, there is provided a microlens sheet having a microlens array section in which unit lenses are two-dimensionally arranged substantially in a matrix on at least one surface of a substrate. The unit lens is formed on only one side of the substrate and includes a unit lens having an aspherical curved surface.
A microlens sheet having a thickness of not more than μm.

In order to arrange the unit lens groups in parallel at a high definition pitch, it is preferable to form the micro lens array portion with a radiation curable resin. The invention according to claim 2 is a microlens sheet having a microlens array section in which unit lenses are two-dimensionally arranged in a substantially two-dimensional matrix on at least one surface of a substrate, wherein the microlens array section reacts with radiation-curable resin. A microlens sheet comprising a cured product obtained by polymerizing and adhering to only one surface of a substrate, including a unit lens having an aspherical curved surface, and an arrangement pitch of the unit lens being 100 μm or less.

The micro-lens array section may be composed of only unit lenses having a spherical curved surface.

The arrangement of the unit lenses is desired, and even if the matrix arrangement is an orderly matrix pattern (a grid pattern),
The array may be a delta array or a honeycomb array.

In order to improve the contrast of the displayed image as a rear projection screen, a light-shielding layer is provided on the surface of the substrate opposite to the microlens array portion, at a position corresponding to the non-light-collecting portion of each unit lens. It is preferable to adopt a configuration in which is formed.

[0020]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing the microlens sheet 10. On one surface of a substrate 11, a microlens array portion 12 made of a reaction-cured product of a radiation-curable resin.
Are superposed and adhered, and the microlens array section 12 has a configuration in which unit lenses 13 having an aspherical curved surface are arranged at a pitch of 100 μm or less. Although FIG. 1A shows a state where adjacent unit lenses 13 are in contact with each other, as shown in FIG. 1B, the adjacent unit lenses 13 may be separated from each other.

If there is no demand for high definition until the unit lenses 13 are arranged at a pitch of 100 μm or less, the microlens array section 12 does not need to be formed of a reaction-cured product of a radiation-curable resin. It may be formed by press molding on the surface of the resin sheet.

FIG. 2 is a plan view showing the microlens sheet 10 of FIG. The unit lens 13 is placed on the surface of the substrate 11
Although they are arranged in a substantially matrix at a pitch of 00 μm or less, there is no restriction on the arrangement method, and even if the matrix is arranged in an orderly grid (cross-cut) as shown in FIG.
Even in the delta arrangement shown in FIGS. 2B and 2C,
As shown in FIG. 2D, a honeycomb-shaped array may be used. In the case of the arrangement shown in FIG. 2A, as described in FIG. 1, it is assumed that adjacent unit lenses 13 are in contact with each other or separated from each other.

In the arrangement shown in FIGS. 2B, 2C and 2D,
A finer periodicity (in the example of FIG. 2C, a new 50 μm pitch period by a combination of the period a and the period b) than the arrangement pitch (assuming 100 μm) of the unit lenses 13 is generated. This further contributes to the reduction of moiré caused by the pitch ratio with respect to the projected pixels from the image, and has an advantage.

In manufacturing such a microlens sheet 10, after forming a stamper for molding, press molding, extrusion molding, or 2P method (Photo-Polymer)
Method).

The stamper is a micro lens sheet 10
(I.e., a surface shape in which the unit lens portion is a concave portion), and other methods such as mechanically carving (or chemically corroding) the concave portion on the surface of the metal layer, and laser processing. Techniques such as carving a concave portion are used. In either method, it is needless to say that it is necessary to accurately process the shape of the curved surface of the unit lens, and a method according to the purpose (definition) is selected.

In forming a light-shielding layer on the flat surface of the substrate 11 on the side opposite to the lens portion of the microlens sheet 10, a photosensitive layer (a known layer which loses adhesiveness by being exposed to light) is formed on the flat surface. After the material is formed on the entire surface, exposure is performed from the microlens array side to modify the photosensitive layer corresponding to the condensing portion and attach ink or toner to the non-condensing portion (the so-called lens itself). A known method called “self-alignment” is preferable for forming a light shielding layer at an accurate position. (Not shown)

[0027]

The microlens sheet according to the present invention is
It is suitable for manufacturing a rear projection screen having a simple structure composed of two lens sheets in combination with a Fresnel lens sheet, and is suitable for visually recognizing a high-resolution image without recognizing moire. .

[0028]

[Brief description of the drawings]

FIG. 1 is a sectional view showing an example of a microlens sheet of the present invention.

FIG. 2 is a plan view showing the microlens sheet of FIG.

[Explanation of symbols]

 10 ... Micro lens sheet 11 ... Substrate 12 ... Micro lens array unit 13 ... Unit lens

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) G03B 21/00 G03B 21/00 EF 21/10 21/10 21/14 21/14 Z

Claims (8)

[Claims] A unit lens is provided on at least one surface of a substrate.
In a microlens sheet having a microlens array portion formed in a substantially matrix arrangement in a dimension, the microlens array portion is formed on only one surface of the substrate and includes a unit lens having an aspherical curved surface, A microlens sheet having a lens arrangement pitch of 200 μm or less. 2. A unit lens is provided on at least one surface of a substrate.
In a microlens sheet having a microlens array portion which is arranged approximately in a matrix in a three-dimensional manner, the microlens array portion is formed by reacting and curing a radiation-curable resin on only one surface of a substrate and forming an aspheric surface. A microlens sheet, comprising: a unit lens having a curved surface, wherein an array pitch of the unit lens is 100 μm or less. 3. The microlens sheet according to claim 1, wherein the microlens array section has only a unit lens having a spherical curved surface. 4. The arrangement of unit lenses is in a grid pattern (a grid pattern).
4. A matrix arrangement according to claim 1, wherein
The microlens sheet according to any one of the above. 5. An arrangement of unit lenses, wherein the arrangement of unit lenses is a delta arrangement or a honeycomb arrangement.
The microlens sheet according to any one of the above. 6. A structure in which a light-shielding layer is formed at a position corresponding to a non-light-collecting portion of each unit lens on the surface of the substrate opposite to the microlens array portion.
The microlens sheet according to any one of claims 1 to 5, wherein 7. The microlens sheet and the Fresnel lens sheet according to any one of claims 1 to 6, wherein the lens array portions are opposed to each other and the Fresnel lens sheet is on the projector side (light source side). A rear projection screen characterized by: 8. A display device comprising a liquid crystal projector or a digital micromirror device as a light source and comprising the rear projection screen according to claim 7.