JP3820115B2 - Transmission type screen and rear projection type image display apparatus using the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a transmissive screen on which image light is projected to display an image, and a rear projection image display apparatus using the transmissive screen.
[0002]
[Prior art]
A conventionally known transmissive screen for a rear projection type image display device includes, for example, a Fresnel lens sheet, a light emission, as described in Japanese Patent Application Laid-Open No. 58-59436 (first example). It is composed of two sheets of a horizontal lenticular lens sheet having a light absorbing layer (black stripe strip) on its surface, or as described in JP-A-58-216235 (second example) In addition, there is a structure in which a light absorption layer (light-shielding layer) is provided on the light exit surface and a single sheet is provided with a plurality of convex lenses on both the light entrance surface and the light exit surface.
[0003]
In these screens, the combination of a Fresnel lens and a horizontal lenticular lens and a convex lens brighten up to the periphery of the screen and work to widen the viewing range, the light absorption layer absorbs external light and stray light inside the screen, It works to improve contrast.
[0004]
In the two-sheet screen composed of the Fresnel lens sheet and the horizontal lenticular lens sheet shown in the first example, the two sheets of the Fresnel lens sheet and the horizontal lenticular lens sheet sandwich an air layer between the sheets. Therefore, the screen is deformed due to expansion and contraction due to changes in temperature and humidity, and the two sheets are separated from each other, which may cause the image projected on the screen to be out of focus. Further, in the one-piece screen having convex lenses on both sides as shown in the second example, the distance from the image element such as a cathode ray tube or a liquid crystal panel to the screen is short (that is, a projection lens for enlarging image light). In an optical system with a large angle of view, sufficient brightness around the screen cannot be obtained.
[0005]
[Problems to be solved by the invention]
An object of the present invention is to provide a transmission type screen that solves such problems, reduces the focus blur, and can obtain sufficient brightness even around the screen in a single-sheet configuration.
[0006]
[Means for Solving the Problems]
In order to solve the above problems, in the present invention,
(1) As a transmission type screen, a plurality of spherical or aspherical convex lenses having a spherical shape as viewed from the light incident surface side are arranged on the light incident surface, and a Fresnel lens is disposed on the light emitting surface. The plurality of convex lenses formed on the light incident surface are arranged concentrically, and the concentric circles of the Fresnel lens are arranged so as to correspond to the concentric circles 1: 1 .
(2) As a transmission screen, in addition to the configuration described in (1) above, the Fresnel lens surface is arranged at a substantially focal position of each convex lens formed on the light incident surface.
(3) As a transmissive screen, in addition to the configuration described in (1) above, a light beam that has passed through each convex lens formed on a light incident surface passes through an effective surface of the Fresnel lens corresponding to each convex lens. To do.
(4) As a transmissive screen, in addition to the configuration described in any one of (1) to (3) above, a light absorption layer is provided in a range that does not block light rays that have passed through the convex lenses formed on the light incident surface. To.
(5) As a transmissive screen, in addition to the configuration described in (4) above, the area of the light absorption layer is set to be 50% or more of the entire screen.
(6) As a transmission type screen, in addition to the configuration described in any one of (1) to (5) above, a plurality of convex lenses formed on the light incident surface are concentrically arranged, and the concentric circle is 1: 1. The concentric circles of the Fresnel lens are arranged so as to correspond.
(7) As a transmissive screen, in addition to the configuration described in (4) or (5) above, image light blocks the position of the light transmission range of the Fresnel lens corresponding to each convex lens formed on the light incident surface. In order to prevent this, the image light is shifted toward the periphery of the Fresnel lens according to the angle of view of the projection lens that magnifies and projects the image light.
(8) As a transmissive screen, in addition to the configuration described in (4) or (5) above, the plurality of convex lenses formed on the light incident surface are arranged concentrically, and correspond to the concentric circles 1: 1. Projection in which the image light is enlarged and projected so that the image light is not obstructed at the position of the light transmission range of the Fresnel lens corresponding to each convex lens formed on the light incident surface by arranging concentric circles of the Fresnel lens. It shifts to the peripheral part side of the Fresnel lens according to the angle of view of the lens.
(9) The transmissive screen according to any one of (1) to (8) above is applied to a rear projection type image display apparatus that magnifies image light by a projection lens optical system and projects the image light onto the transmissive screen from the rear side. It uses a configuration.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following drawings, the same reference numerals are given to the same parts in the drawings.
[0008]
FIG. 1 shows a first embodiment of the present invention. In this embodiment, in a single screen transmissive screen , a plurality of two-dimensional spherical or aspherical convex lenses having a spherical shape as viewed from the light incident surface side are provided on the light incident side. , Rutotomoni on the light emission side is provided a concentric Fresnel lens, a plurality of the convex lenses formed on the light incident surface disposed concentrically, 1 to the concentric circle: the concentric corresponding manner the Fresnel lens arranged in a 1 This is a configuration of a transmission screen.
[0009]
In FIG. 1, 1 is an image display element such as a liquid crystal panel, 2 is a projection lens, 3 is a transmission screen (hereinafter abbreviated as “screen”), and 4 is a plurality of two-dimensionally provided on the incident side of the screen 3. convex spherical or aspherical shape is formed in a spherical shape as viewed from the light incident side, 5 Ri Fresnel lens der, a plurality of the convex lenses 4 formed on the light incident surface disposed concentrically, the The concentric circles of the Fresnel lens 5 were arranged so as to correspond to the concentric circles at a ratio of 1: 1 .
[0010]
In FIG. 1, the image light formed by the image display element 1 is magnified by the projection lens 2 and projected onto the screen 3. On the screen 3, the image light is diffused by the convex lenses 4 and is incident on the Fresnel lens 5 in a state where the viewing range is expanded in the horizontal and vertical directions. In the Fresnel lens 5, the diffused light diffused by the convex lenses 4. The chief ray is emitted in a state in which the principal ray is substantially parallel to the optical axis of the projection lens 2. The viewer views the emitted light from the Fresnel lens 5 as a projection image.
[0011]
According to the present invention, a viewer can view a projected image having a wide viewing range and bright up to the periphery of the screen. If a Fresnel lens is provided on the light incident side, as described in Japanese Patent Laid-Open No. 58-59436, more image light is incident on the ineffective surface of the Fresnel lens around the screen, and the light utilization is increased. Since the efficiency is poor, the Fresnel lens in the transmission screen of the present invention is provided on the light exit side.
[0012]
FIG. 2 is a cross-sectional view of FIG. 1 as viewed from above, where x indicates a central portion of the screen and y indicates a peripheral portion of the screen.
[0013]
As described above, the transmissive screen of the present invention has a spherical surface or aspherical convex lens having a spherical shape when viewed from the light incident surface side on the light incident surface, and a Fresnel lens on the light output surface. And a plurality of convex lenses formed on the incident surface are arranged concentrically, and concentric circles of the Fresnel lens are arranged so as to correspond to the concentric circles at a ratio of 1: 1 .
[0014]
FIG. 3 is an enlarged view of a portion x in FIG. In FIG. 3A, the pitch between the convex lens 4 and the Fresnel lens 5 corresponds to 1: 1, and the image light that has passed through the convex lens 4 is once condensed at the focal point of the convex lens and then diffused. Are arranged to be incident on the effective surface of the Fresnel lens 5. FIG. 3B shows an example in which the pitch of the convex lens 4 and the Fresnel lens 5 corresponds to 1: 1, and the position of the Fresnel lens 5 is arranged near the focal length of the convex lens 4. Since the effective surface of the Fresnel lens 5 exists at the position, the image light is not easily deviated from the effective surface of the Fresnel lens even if the convex lens and the Fresnel lens are misaligned due to manufacturing variations. FIG. 3C shows an embodiment in which the pitch of the convex lens 4 is made smaller than the pitch of the Fresnel lens 5, and a part of the image light is also incident on the ineffective surface of the Fresnel lens. Even in this case, the screen functions sufficiently because more image light enters.
[0015]
As shown in FIGS. 3A and 3B, the transmissive screen of the present invention has a Fresnel lens surface disposed at a substantially focal position of each convex lens formed on the light incident surface.
[0016]
FIGS. 4A to 4C show the peripheral portions of FIG. 2 corresponding to the screens of FIGS. 3A to 3C (enlarged views of the portion y in FIG. 2). As shown in FIG. 2, the image light enters obliquely at the screen peripheral part y. Therefore, when the pitch of the convex lens 4 and the Fresnel lens 5 corresponds to 1: 1, in order to make the image light effectively incident on the effective surface of the Fresnel lens 5, the position of the effective surface of the Fresnel lens 5 is set to the convex lens. It is necessary to shift the position 4 in accordance with the angle of view of the projection lens, and embodiments thereof are shown in FIGS.
[0017]
As shown in FIGS. 4A and 4B, in the transmissive screen of the present invention, the light beam that has passed through each convex lens formed on the light incident surface passes through the effective surface of the Fresnel lens corresponding to each convex lens. Arranged.
[0018]
As shown in FIGS. 4A and 4B, the transmissive screen of the present invention projects the image light at the position of the light transmission range of the Fresnel lens corresponding to each convex lens formed on the light incident surface. Shifted to the peripheral side of the Fresnel lens according to the angle of view of the projection lens. Further, the plurality of convex lenses formed on the light incident surface are arranged concentrically, the concentric circles of the Fresnel lens are arranged so as to correspond to the concentric circles at a ratio of 1: 1, and each convex lens formed on the light incident surface corresponds. The position of the light transmission range of the Fresnel lens was shifted to the peripheral side of the Fresnel lens according to the angle of view of the projection lens that magnifies and projects the image light.
[0019]
In the case of FIG. 4C, since the number of convex lenses corresponding to one pitch of the Fresnel lens 5 is large, the amount of light incident on the effective surface of the Fresnel lens 5 hardly changes even if the position is shifted. Need not consider the position of the effective surface of the Fresnel lens 5.
[0020]
Next, an embodiment in which a light absorbing layer is added to the screen to absorb external light and stray light inside the screen to improve contrast will be described. FIGS. 5A, 5B, and 6 show an embodiment of the invention in which a light absorbing layer 6 having a light transmitting portion 7 is added to the structures of FIGS. 4A to 4C. 4 is an enlarged view of the peripheral portion y of the screen shown in FIG. 2, but the difference from the central portion of the screen is that the position of the effective surface of the Fresnel lens 5 is shifted with respect to the convex lens 4. Since only the (shifted) configuration is used, in the contents described below, the center portion of the screen is omitted, and description will be made using only the peripheral portion of the screen.
[0021]
FIG. 5A is an example having a structure in which a light absorbing layer 6 having a light transmitting portion 7 is provided inside the transmissive screen 3, and the area of the light absorbing layer 6 does not block image light. Is provided in the screen 3 at a position shifted according to the angle of view of the projection lens, avoiding the light transmission range (light transmission portion) 6 in the vicinity of the focal position of the convex lens 4 so as to be as large as possible. It is. With such a configuration, the light absorption layer 6 can absorb external light or stray light due to reflection inside the screen without shielding the image light, so that a bright and high-contrast image can be displayed on the screen. Can be projected.
[0022]
FIG. 5B shows an embodiment in which the light absorbing layer 6 is provided on the surface of the Fresnel lens 5 because the position of the Fresnel lens 5 is substantially at the focal point of the convex lens 4. Although not shown here, since the shape of the Fresnel lens surface where the light absorption layer 6 is provided is a portion where no image light is incident, the light absorption layer 6 is not necessarily as shown in FIG. It is not necessary to have a serrated cross-sectional shape, and any shape may be used as long as it does not block image light and absorbs stray light or reflected light. FIG. 6 shows an embodiment in which a light absorption layer 6 is added to the structure of FIG.
[0023]
As shown in FIGS. 5 and 6, the transmissive screen of the present invention is provided with a light absorption layer 6 in a range that does not block the light beam that has passed through each convex lens formed on the light incident surface.
[0024]
Figure 7 is a front view of the screen 3 from the light incident side, with a shape as viewed from the light incident side are arranged a plurality of convex lens 4 to concentric spherical or aspherical shape formed in a spherical shape In this embodiment, the plurality of convex lenses formed on the incident surface are concentrically arranged, and the concentric circles of the Fresnel lens are arranged so as to correspond to the concentric circles at a ratio of 1: 1 . Note that the convex lens at the periphery of the screen is omitted so that it can be easily understood that it is a concentric circle. With such an arrangement, the light collected by the convex lens 4 on the same concentric circle can be incident on the effective surface of the corresponding Fresnel lens on the concentric circle in a one-to-one correspondence.
[0025]
As shown in FIG. 7 , the transmissive screen of the present invention has a plurality of convex lenses formed in a spherical shape on a light incident surface arranged concentrically, and the concentric circles of the Fresnel lens correspond to the concentric circles 1: 1. Arranged.
[0026]
FIG. 8 is a front view of the screen 3, which is an embodiment in which the light absorption layer 6 is added to the configuration of FIG. 7, and shows the shape of the light absorption layer 6. In this case, as shown in the drawing, in the light absorbing layer 6, the light transmitting portions 7 are arranged concentrically so as to substantially correspond to the convex lens 4.
[0027]
In any case, the area of the light absorption layer 6 described above is desirably 50% or more in order to obtain good contrast.
[0028]
FIG. 7 shows an embodiment in which the convex lenses 4 are arranged concentrically. However, even if the convex lenses are randomly arranged, the Fresnel lens is formed in a discontinuous concentric shape, and the position of the effective surface of the Fresnel lens is a convex lens. If the correspondence is 1: 1, the effect of the present invention can be obtained.
[0029]
FIG. 9 shows an embodiment in which a transmission screen according to the present invention is used in a rear projection type image display apparatus.
[0030]
In FIG. 9, 1 is an image display element such as a liquid crystal panel, 2 is a projection lens, 3 is a transmission screen according to the present invention, 15 is a light source unit, 20 is a mirror, and 30 is a drive circuit for the image display element 1. Light from the light source unit 15 is modulated by the image display element 1 and emitted as image light, magnified by the projection lens 2, reflected by the mirror 20, and then projected from the back onto the transmissive screen 3. The
[0031]
Thus, the rear projection type image display device using the transmission screen according to the present invention is an image display device that can reduce the focus blur and can obtain sufficient brightness even on the periphery of the screen capable of displaying a good image. be able to.
[0032]
【The invention's effect】
According to the present invention, it is possible to reduce the focus blur with a single-sheet configuration and obtain a sufficient brightness even on the periphery of a screen capable of displaying a good image, and a rear surface using the transmission screen. A projection type image display device can be provided.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a configuration of a transmissive screen according to a first embodiment of the present invention.
FIG. 2 is a top sectional view of the transmission screen shown in FIG.
3 is a cross-sectional view of the screen center of the transmissive screen shown in FIG.
4 is a cross-sectional view of the periphery of the transmissive screen shown in FIG. 2;
5 is a cross-sectional view of the periphery of a screen having a configuration in which a light absorption layer is added to the transmission screen shown in FIG.
6 is a cross-sectional view of the periphery of a screen having a configuration in which a light absorption layer is added to the transmissive screen shown in FIG. 2;
FIG. 7 is a front view of the screen for explaining the arrangement of the lenses of the transmission screen according to the embodiment of the present invention.
FIG. 8 is a screen front view illustrating the shape of the light absorption layer of the transmission screen according to the embodiment of the invention.
FIG. 9 is a diagram showing an embodiment of a rear projection type image display device using a transmissive screen.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Image display element 2 Projection lens 3 Transmission type screen 4 Convex lens 5 Fresnel lens 6 Light absorption layer 7 Light transmission part 15 Light source unit 20 Mirror 30 Image display element drive circuit

Claims (8)

A plurality of spherical or aspherical convex lenses having a spherical shape as viewed from the light incident surface side are arranged on the light incident surface of the transmissive screen , a Fresnel lens is disposed on the light emitting surface, and the light incident surface. A transmissive screen comprising a plurality of convex lenses arranged in a concentric manner, and concentric circles of the Fresnel lens arranged so as to correspond to the concentric circles in a ratio of 1: 1 .   The transmissive screen according to claim 1, wherein the Fresnel lens surface is disposed at a substantially focal position of each convex lens formed on a light incident surface.   The transmissive screen according to claim 1, wherein a light beam that has passed through each convex lens formed on a light incident surface passes through an effective surface of the Fresnel lens corresponding to each convex lens.   The transmissive screen according to any one of claims 1 to 3, wherein a light absorbing layer is provided in a range that does not block a light beam that has passed through each convex lens formed on a light incident surface.   The transmission screen according to claim 4, wherein the area of the light absorption layer is 50% or more of the entire screen. The position of the optical transmission range of the Fresnel lens corresponding to the pre-Symbol the convex lenses formed on the light incident surface, it has shifted to the peripheral portion of the Fresnel lens according to the field angle of the projection lens for enlarging and projecting the image light The transmissive screen according to claim 4, wherein: A plurality of convex lenses formed on the light incident surface disposed concentrically, 1 to the concentric circle: the concentric corresponding manner the Fresnel lens arranged in a 1, and, corresponding to the respective convex lenses formed on the light incident surface The position of the light transmission range of the Fresnel lens to be shifted to the peripheral side of the Fresnel lens according to the angle of view of the projection lens that magnifies and projects the image light. Transmissive screen. 8. A rear projection type image display apparatus for projecting image light by a projection lens optical system and projecting the image light onto a transmissive screen from the rear side, wherein the transmissive screen is any one of claims 1 to 7. A rear projection type image display device using the transmissive screen according to the item .

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