JPH10123623A - Transmission type projection screen - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the light utilization efficiency. SOLUTION: A transmission type projection screen is provided with a reflecting layer 13 having small holes in parts corresponding to a large number of micro lenses 11a between a micro lens array layer 11 having a large number of micro lens 11a for convergence arranged in the matrix, and a diffusion layer 12. The diffusion layer 12 comprises the diffusion material 12a diffused inside the layer 12. The light incident on a back side of the micro lens array layer 11 passes through the corresponding small hole 13a in the reflecting layer 13 after converged by each micro lens 11a, and the transmitted light is diffused by the diffusion layer 12 and emitted from the surface of the diffusion layer 12. Even when the light reflected by the surface of the diffusion layer 12 and the surface of the diffusion material 12 is propagated toward the micro lens array layer 11, most of the light is reflected by the surface of the reflecting layer 13, and emitted from the surface of the diffusion layer 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission type projection screen used in a liquid crystal projector or the like.

[0002]

2. Description of the Related Art In a liquid crystal projector, for example,
An image displayed on the liquid crystal display panel is enlarged and projected on a transmission type projection screen by a projection lens. FIG.
And FIG. 10 show examples of transmission projection screens used in such a conventional liquid crystal projector, respectively.

In the transmission type projection screen shown in FIG. 9, a flat surface of the Fresnel lens 1 whose Fresnel lens surface 1a is on the back side (incidence side, ie, a projection lens side not shown) is formed with silica or glass inside. A flat diffusion plate 2 in which bead-like diffusion materials 2a are dispersed is provided. In this case, the Fresnel lens 1 is for converting the image light from the projection lens into parallel light, and the diffusion plate 2 is for diffusing the parallel light to increase the viewing angle.

In the transmission type projection screen shown in FIG.
Diffusion consisting of a lenticular lens in which a bead-like diffusion material 4a made of silica, glass, or the like is dispersed inside the Fresnel lens 3 with the Fresnel lens surface 3a facing the front side (the exit side, ie, the observer side) The plate 4 has a structure in which the lenticular lens surface 4b is provided on the back side. Also in this case, the Fresnel lens 3 is for converting the image light from the projection lens into parallel light,
The diffusion plate 4 diffuses the parallel light to increase the viewing angle.

[0005]

However, in the transmissive projection screens shown in FIGS. 9 and 10, in each case, the light reflected on the surfaces of the diffusion plates 2 and 4 and the surfaces of the diffusion materials 2a and 4a is not affected. A part returns to the back side (projection lens side),
There is a problem that the light use efficiency is reduced. An object of the present invention is to improve light use efficiency.

[0006]

According to the present invention, there is provided a transmission type projection screen comprising a diffusion layer and a microlens array layer having a large number of condensing microlenses arranged in a matrix. A reflection layer having micropores in portions corresponding to the plurality of microlenses is provided between the lens array layer and the diffusion layer.

According to the present invention, the light incident on the back surface of the microlens array layer passes through the corresponding minute holes of the rear reflection layer collected by each microlens,
The transmitted light is diffused by the diffusion layer and emitted from the surface of the diffusion layer. In this case, even if light reflected by the surface of the diffusion layer or the like proceeds toward the microlens array layer, most of the light is reflected by the surface of the reflection layer and emitted from the surface of the diffusion layer. become. Therefore, the light use efficiency can be improved.

[0008]

FIG. 1 is a sectional view of a main part of a transmission type projection screen according to a first embodiment of the present invention, and FIG. 2 is a rear view of a part thereof. In this transmissive projection screen, between the flat surface of the microlens array layer 11 having a large number of condensing microlenses 11a arranged in a matrix on the back surface and the back surface of the flat diffusion layer 12 Reflective layer 13 having minute holes 13a at portions respectively corresponding to a large number of microlenses 11a
Is provided. In this case, the diffusion layer 12
Is made of a material in which a diffusion material 12a is dispersed.

Next, an example of a method of manufacturing the transmission type projection screen will be described. First, a large number of microlenses 1 having a flat surface and arranged in a matrix on the back surface side.
The microlens array layer 11 having 1a is formed by molding using a transparent resin such as an acrylic resin or a polycarbonate resin as a material. Next, an aluminum film for forming the reflection layer 13 is formed on the flat surface of the microlens array layer 11 by vapor deposition or sputtering. Next, laser light is irradiated from the back surface side of the microlens array layer 11. Then, the laser light is collected by each microlens 11a and is intensively irradiated on the aluminum film in a portion corresponding to the central portion of each microlens 11a. The reflection layer 13 having 13a is formed. Next, the resin is diffused to the surface side of the reflective layer 13 by die molding using a material in which a bead-shaped diffusing material 12a made of silica, glass, or the like is dispersed in a transparent resin made of an acrylic resin, a polycarbonate resin, or the like. The layer 12 is formed. In this case, the fine holes 13 a of the reflection layer 13 are filled with the diffusion layer 12. Thus, the transmission projection screen shown in FIGS. 1 and 2 is obtained.

In the transmission type projection screen shown in FIG. 1, light incident on the back surface of the microlens array layer 11 passes through the corresponding minute holes 13a of the rear reflection layer 13 collected by each microlens 11a. The transmitted light is diffused by the diffusion layer 12 and emitted from the surface of the diffusion layer 12. In this case, the diffusion layer 12
Even if the light reflected by the surface of the diffuser 12a advances toward the microlens array layer 11, most of the light is reflected by the surface of the reflective layer 13 and emitted from the surface of the diffuser layer 12. Will be done. Therefore, the light use efficiency can be improved.

Next, another embodiment of the present invention will be described. Only the structure of the diffusion layer 12 in the following embodiment differs from the first embodiment. I do. First, as shown in FIG.
The diffusion layer 12 in the embodiment has, on the surface thereof, portions corresponding to the plurality of microlenses 11a of the microlens array layer 11, a projection 12c partitioned by a groove 12b having a substantially V-shaped cross section, and Convex part 1
The interface between the groove 2c and the groove 12b (the wall surface of the convex portion 12c) is a reflection surface. For this reason, one convex part 12c
Even if the light reflected by the surface of the first protrusion 12c or the surface of the diffusion material 12a in the one protrusion 12c travels toward the adjacent another protrusion 12c, most of the light is transmitted by the one protrusion 12c.
The light is reflected by a reflection surface or the like formed at the interface with the groove 12b, and is emitted from the surface of the one convex portion 12c. Therefore, light that travels along the surface of the diffusion layer 12 and attenuates can be effectively used. Therefore, the light use efficiency can be further improved, and the contrast can be improved. In addition, as a method of forming the groove 12b, the diffusion layer 1
There is a method of simultaneously forming 2 by forming with a mold. Further, the cross-sectional shape of the convex portion 12c is trapezoidal, but the planar shape may be any of a circle and a square.

Next, the diffusion layer 12 in the third embodiment shown in FIG.
A plurality of microlenses 11a are each provided with a projection 12c partitioned by a groove 12b having a substantially V-shaped cross section, and a reflection layer 12d made of aluminum is provided between the projections 12c. It has a structure. Therefore, also in the case of the third embodiment, the light use efficiency can be further improved, and the contrast can be improved. In addition, as a method for forming the reflective layer 12d, after forming the projections 12c and the like by die molding, an aluminum film is formed on the entire upper surface including the inside of the groove 12b by vapor deposition or sputtering, and the formed aluminum film is formed. There is a method of removing unnecessary portions by photolithography. In this case, even if the depth of the groove 12b reaches the surface of the reflective layer 13, the inside of the groove 12b
Since it is filled with d, the intensity of the whole transmissive projection screen can be increased.

Next, the diffusion layer 12 in the fourth embodiment shown in FIG.
Has a substantially hemispherical convex portion 12e at a portion corresponding to each of a large number of microlenses 11a, and has a diffusing material 1 therein.
2a is dispersed. The case of the fourth embodiment is almost the same as the case of the second embodiment shown in FIG. 3, so that the light use efficiency can be further improved and the contrast can be improved.

Next, the diffusion layer 12 in the fifth embodiment shown in FIG. 6 is different from that of the first embodiment shown in FIG. Thus, a structure is formed in which the uneven diffusion surface 12f is formed. Therefore, in this case, even if the light reflected by the diffusion surface 12f of the diffusion layer 12 advances toward the microlens array layer 11, most of this light is reflected by the surface of the reflection layer 13 and diffused. The light is emitted from the diffusion surface 12f of the layer 12, and the light use efficiency can be improved.

Next, the diffusion layer 12 in the sixth embodiment shown in FIG.
The projections 12 divided by substantially V-shaped grooves 12g are provided at portions corresponding to the plurality of microlenses 11a, respectively.
h, and the interface between the projections 12h and the grooves 12g is a reflection surface. Next, the diffusion layer 12 in the seventh embodiment shown in FIG.
Have convex portions 12h partitioned by a substantially V-shaped groove 12g, and
The structure is such that the reflection layer 12i is provided between 2h.
Therefore, the sixth and seventh states shown in FIGS. 7 and 8, respectively.
In the case of the embodiment, the light use efficiency can be further improved, and the contrast can be improved.
Further, in the case of the seventh embodiment shown in FIG. 8, the intensity of the entire transmissive projection screen can be increased.

[0016]

As described above, according to the present invention, even if light reflected by the surface of the diffusion layer or the like proceeds toward the microlens array layer, most of the light is reflected by the reflection layer. Since the light can be reflected from the surface and emitted from the surface of the diffusion layer, the light use efficiency can be improved.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part of a transmission projection screen according to a first embodiment of the present invention.

FIG. 2 is a rear view of a part of the transmission type projection screen shown in FIG. 1;

FIG. 3 is a sectional view of a main part of a transmission type projection screen according to a second embodiment of the present invention.

FIG. 4 is a sectional view of a main part of a transmission projection screen according to a third embodiment of the present invention.

FIG. 5 is a sectional view of a main part of a transmission type projection screen according to a fourth embodiment of the present invention.

FIG. 6 is a sectional view of a main part of a transmission type projection screen according to a fifth embodiment of the present invention.

FIG. 7 is a sectional view of a main part of a transmission type projection screen according to a sixth embodiment of the present invention.

FIG. 8 is a sectional view of a main part of a transmission type projection screen according to a seventh embodiment of the present invention.

FIG. 9 is a partial cross-sectional view of an example of a conventional transmission type projection screen.

FIG. 10 is a partial cross-sectional view of another example of a conventional transmission projection screen.

[Explanation of symbols]

 Reference Signs List 11 microlens array layer 11a microlens 12 diffusion layer 12a diffusion material 13 reflection layer 13a micropore

Claims (8)

[Claims] 1. A transmissive projection screen in which a diffusion layer and a microlens array layer having a large number of light-collecting microlenses arranged in a matrix are stacked, wherein the microlens array layer, the diffusion layer, Wherein a reflective layer having minute holes is provided in portions corresponding to the plurality of microlenses, respectively. 2. A transmission type projection screen according to claim 1, wherein said diffusion layer comprises a diffusion material dispersed therein. 3. The invention according to claim 2, wherein the diffusion layer has convex portions partitioned by grooves at portions corresponding to the plurality of microlenses on the front surface side, respectively. A transmissive projection screen comprising a reflection surface at an interface with the groove. 4. The invention according to claim 2, wherein the diffusion layer has, at portions corresponding to the plurality of microlenses on the front surface side, convex portions partitioned by grooves, and a gap between these convex portions. A transmissive projection screen comprising a reflective layer. 5. The transmissive projection according to claim 2, wherein the diffusion layer has a substantially hemispherical convex portion on a surface corresponding to each of the plurality of microlenses. screen. 6. The transmissive projection screen according to claim 1, wherein the diffusion layer has a surface with an uneven diffusion surface. 7. The invention according to claim 6, wherein the diffusion layer has convex portions partitioned by grooves at portions corresponding to the plurality of microlenses on the surface side, respectively. A transmissive projection screen comprising a reflection surface at an interface with the groove. 8. The invention according to claim 6, wherein the diffusion layer has convex portions partitioned by grooves at portions corresponding to the plurality of microlenses on the front surface side, and a space between the convex portions. A transmissive projection screen comprising a reflective layer.