JP7226119B2 - Transmissive screen, image display device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a transmissive screen and an image display device having the same.

2. Description of the Related Art Conventionally, as one of image display devices, a transmissive screen that displays an image by allowing image light projected from an image source to pass therethrough, and a rear projection image display device including the screen are known. 2. Description of the Related Art Various developments have been made on transmissive screens and rear projection type image display devices, such as improvement of image contrast and viewing angle.
Conventional transmissive screens have very low transparency in order to prevent the image source located behind from being seen through (see-through phenomenon) and to improve image contrast. It is common that the view of the road is not visible.

In recent years, there has been a demand for highly transparent screens that can be installed in the show windows of stores to display images, and that allow the scenery on the other side of the screen to be clearly seen when no image light is projected. rising. In addition, transmissive screens having such transparency have also been developed (see, for example, Patent Document 1).

Japanese Patent No. 4847329

The aforementioned Patent Document 1 discloses a transmissive screen provided with a light diffusion layer containing fine particles. This light diffusion layer is formed in a form in which the transparent binder contains fine particles having a refractive index different from that of the transparent binder.
However, in a transmissive screen provided with such a light diffusion layer, both image light and outside light other than image light, such as sunlight and illumination light, are similarly diffused. Under environmental conditions, the transmissive screen itself appears whitish, resulting in a loss of transparency.

In addition, in transmissive screens with enhanced transparency, part of the image light projected from below is directed upwards on the viewer's side of the screen, and the image light is reflected on the ceiling or the like, creating a vague area of light. In addition, there is a problem that it prevents the observer from comfortably viewing the image, and that the comfort and design of the environment in which the image is displayed are impaired.

SUMMARY OF THE INVENTION An object of the present invention is to provide a transmissive screen with high transparency and reduced reflection of unnecessary image light on the ceiling or the like, and an image display device including the same.

The present invention solves the above problems by means of the following solutions. In order to facilitate understanding, reference numerals corresponding to the embodiments of the present invention are used for explanation, but the present invention is not limited to these.
A first aspect of the invention is a transmissive screen that transmits at least part of image light (L) for display, and is located inside the transmissive screen on the side of a light incident surface (10a) on which the image light is incident. a plurality of unit optical shapes (121, 221, 321) arranged in a first direction parallel to at least the screen surface, and a film-like laminate on the light incident surface side of the unit optical shape, A reflecting layer (13) for transmitting a part of the image light incident from the light incident surface and reflecting a part of the image light incident from the light incident surface toward a light exit surface opposite to the light incident surface. and a light absorbing portion (15, 45) formed between the arranged adjacent unit optical shapes to absorb light, wherein the unit optical shapes are arranged in the first direction and the transmissive screen. The cross-sectional shape in the cross section parallel to the thickness direction of the is substantially rectangular, the surface closest to the light incident surface is defined as the second surface (123), and the Of the two opposing surfaces, the one forming a larger angle with the normal direction of the screen surface is defined as a first surface (122), and the smaller one is defined as a third surface (124). A transmissive screen (10, 20, 30, 40) characterized by being formed on the first surface and the second surface.
A second invention is the transmissive screen according to the first invention, characterized in that the reflective layer (13) has an uneven shape on its surface and diffusely reflects part of the incident light. Mold screens (10, 20, 30, 40).
A third invention is the transmissive screen according to the first invention or the second invention, wherein an angle θ2 formed between the first surface (122) and a normal direction of the screen surface is 5° or more and 20° or less. A transmissive screen (10, 20, 30, 40) characterized by:
A fourth invention is the transmissive screen according to any one of the first invention to the third invention, wherein the light absorbing portion (15) fills the valleys between the unit optical shapes (121). A transmissive screen (10, 20, 30) characterized in that it is formed in
A fifth aspect of the invention is characterized in that, in the transmissive screen according to any one of the first to fourth aspects, the second surface (123) is parallel to the screen surface of the transmissive screen. It is a transmissive screen (10).
A sixth aspect of the invention is the transmissive screen according to any one of the first to fourth aspects of the invention, wherein the second surface (123) has an end portion (123a) on the first surface side that extends from the second surface. The transmissive screen (20) is characterized by being inclined so as to be located closer to the light incident surface (10a) than the end (123b) on the surface side of No. 3.
A seventh invention is the transmissive screen according to the sixth invention, wherein an angle θ1 formed by the first surface (122) and the second surface (123) is 85° or more and less than 95°, A transmissive screen (20) characterized by
An eighth invention is the transmissive screen according to any one of the first invention to the fourth invention, wherein the second surface (123) has an end portion (123b) on the side of the third surface that extends from the third surface. The transmissive screen (30) is characterized in that it is inclined so as to be located closer to the light incident surface (10a) than the end (123a) on the surface 1 side.
In a ninth aspect of the invention, in the transmissive screen of the eighth aspect, the angle θ1 formed by the first surface (122) and the second surface (123) is the most forward angle in the thickness direction of the transmissive screen. When n is the refractive index of the layer (14) which is located on the side of the light entry surface (10a) and forms an interface with the air, 1/2×arcsin(1/n)+103°≦θ1≦1/2×arcsin A transmissive screen (30) characterized by satisfying the formula (1/n)+107°.
A tenth invention is a transmissive screen according to any one of the first to ninth inventions, and an image source ( LS) and a video display device (1).

Advantageous Effects of Invention According to the present invention, it is possible to provide a transmissive screen with high transparency and reduced reflection of unnecessary images on the ceiling or the like, and an image display device including the same.

It is a figure which shows the video display apparatus 1 of 1st Embodiment. It is a figure explaining the screen 10 of 1st Embodiment. 4A and 4B are diagrams illustrating states of image light and external light incident on the screen 10 of the first embodiment; FIG. It is a figure explaining the screen 20 of 2nd Embodiment. It is a figure explaining the screen 30 of 3rd Embodiment. It is a figure explaining the screen 40 of 4th Embodiment.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings.
In addition, each figure shown below including FIG. 1 is a schematic diagram, and the size and shape of each part are appropriately exaggerated for easy understanding.
In this specification, terms that specify shapes and geometric conditions, for example, terms such as parallel and orthogonal, have the same optical function and can be regarded as parallel or orthogonal in addition to the strict meaning. It shall include the state with an error of
In addition, numerical values such as dimensions and material names of each member described in this specification are examples as an embodiment, and are not limited to these, and may be appropriately selected and used.

In this specification, the terms plate, sheet, etc. are used, and as a general usage, these are used in order of thickness, plate, sheet, film, and are used in this specification. Among other things, it is used in imitation of it. However, such proper use has no technical meaning, so these words can be replaced as appropriate.

(First embodiment)
FIG. 1 is a diagram showing an image display device 1 according to the first embodiment. FIG. 1 shows the image display device 1 viewed from the side (from the X direction described later).
The video display device 1 is a rear projection display device including a screen 10, a video source LS, and the like. The image source LS located on the back side (light incident side) of the screen 10 projects the image light L onto the screen 10, the screen 10 transmits the image light L, and the screen 10 is located on the front side (light emitting side) in the front direction. An image is displayed to the observer O1 who is doing this.

Here, in order to facilitate understanding, an XYZ orthogonal coordinate system is appropriately provided and shown in each figure shown below including FIG. In this coordinate system, the horizontal direction of the screen 10 is the X direction, the vertical direction of the screen is the Y direction, and the thickness direction of the screen 10 is the Z direction. The screen (display surface) of the screen 10 is parallel to the XY plane, and the thickness direction (Z direction) of the screen 10 is orthogonal to the screen (XY plane) of the screen 10 .
In the Z direction, the direction from the image source LS side to the observer O1 side (the direction from the light entrance side to the light exit side) is defined as +Z direction. The +X direction is the rightward direction in the X direction (horizontal direction of the screen), and the +Y direction is the upward direction in the Y direction (vertical direction of the screen) when viewed from the observer O1 positioned in the front direction on the light exit side of the screen 10. and

In the following description, the up-down direction of the screen, the left-right direction of the screen, and the thickness direction refer to the up-down direction of the screen (vertical direction), the left-right direction of the screen (horizontal direction), and the thickness direction, unless otherwise specified. (depth direction) and parallel to the Y direction, X direction, and Z direction, respectively. Further, the light incident side and the light exiting side are assumed to be the light incident side (-Z side) and the light exiting side (+Z side) of the image light L projected from the image source LS.
Further, in the following description, the term "screen surface" refers to a surface in the plane direction of the screen 10 when the screen 10 is viewed as a whole, and the same definition is used in the scope of claims. The screen plane is parallel to the XY plane.

The image source LS is an image projection device that projects the image light L onto the screen 10, and is, for example, a short-focus projector.
When the image display device 1 is in use, the image source LS is positioned at the center of the screen 10 in the horizontal direction of the screen and on the lower side (-Y side) in the vertical direction than the screen of the screen 10 .
The image source LS is arranged at a position much closer to the surface of the screen 10 in the depth direction (Z direction) of the image display device 1 than a conventional general-purpose projector. can be projected. Therefore, compared to conventional general-purpose projectors, the image source LS has a short projection distance of the image light L to the screen 10 and a large incident angle of the image light L incident on the screen 10 .

The screen 10 is a transmissive screen that transmits and displays the image light L projected by the image source LS. When the image display device 1 is not in use, that is, when the image source LS does not project image light, the screen 10 allows the observer to view the scenery on the other side of the screen 10 from the light output side (+Z side) as well as the light input side. It has transparency that can be observed from (−Z side).

The screen 10 has a light entrance surface 10a on which the image light L is incident and a light exit surface 10b facing the light entrance surface 10a from which the image light L is emitted. The light entrance surface 10a and the light exit surface 10b are parallel to each other and parallel to the screen surface (XY plane).
Here, as an example, the screen (display area) of the screen 10 has a substantially rectangular shape in which the long side direction is the left and right direction of the screen when viewed from the observer O1 on the light exit side (+Z side) when in use. to explain. The screen 10 has a diagonal screen size of about 40 to 100 inches and a screen aspect ratio of 16:9. Note that the screen size of the screen 10 is not limited to this, and may be, for example, 40 inches or less, and the screen size and shape of the screen 10 can be appropriately selected according to the purpose of use, environment of use, and the like.

In general, the screen 10 is a laminate of thin resin layers or the like, and often does not have sufficient rigidity to maintain flatness by itself. Therefore, it is preferable that the screen 10 is integrally bonded (or partially fixed) to a support plate (not shown) via a bonding layer (not shown) on the light exit side and the light entrance side to maintain the flatness of the screen. As such a support plate and bonding layer, those having optical transparency are used.
The support plate is preferably a plate-shaped member having light transmission properties and high rigidity, and a plate-shaped member made of resin such as acrylic resin or PC (polycarbonate) resin, glass, or the like can be used. Since the image display device 1 of the present embodiment is applied to, for example, a show window of a store, window glass (glass plate) or the like constituting a show window of a store or the like may be used as the supporting plate.
Moreover, the screen 10 is not limited to this, and the screen 10 may be configured such that its four sides or the like are supported by a frame member or the like (not shown) to maintain its flatness.

FIG. 2 is a diagram illustrating the screen 10 of the first embodiment. In FIG. 2, the point A (see FIG. 1) which is the center of the screen (the geometric center of the display area of the screen) on the light exit side (+Z side) of the screen 10 passes through and is parallel to the vertical direction (Y direction) of the screen. , a portion of the cross section perpendicular to the screen surface (parallel to the Z direction) is shown enlarged.
As shown in FIG. 2, the screen 10 includes a substrate layer 11, an optical shape layer 12, a reflective layer 13, a light absorbing portion 15, and a flattening layer 14 in order from the light output side (-Z side).

The base material layer 11 is a sheet-like member having optical transparency. The substrate layer 11 has an optical shape layer 12 integrally formed on the light incident side (−Z side) thereof. The substrate layer 11 is a layer that serves as a substrate (base) for forming the optically shaped layer 12 .
The base material layer 11 is made of polyester resin such as PET (polyethylene terephthalate) having high light transmittance, acrylic resin, styrene resin, acrylic styrene resin, PC resin, alicyclic polyolefin resin, TAC (triacetylcellulose) resin, or the like. It is formed.

The optical shape layer 12 is a layer having optical transparency formed on the light incident side (−Z side) of the base layer 11 . A plurality of unit optical shapes 121 are arranged on the light incident side of the optical shape layer 12 .
The unit optical shape 121 has a substantially quadrangular cross-sectional shape in the cross section shown in FIG. 2, and this cross-sectional shape extends in the horizontal direction (X direction) of the screen. That is, the unit optical shape 121 has a substantially quadrangular prism shape extending in the horizontal direction of the screen in a strip shape. A plurality of unit optical shapes 121 are arranged in the vertical direction (Y direction) of the screen. In addition, the substantially rectangular shape here mainly means a trapezoidal shape, a shape similar thereto, a trapezoidal shape, and those with rounded corners (corners with arc-shaped corners). point to

The unit optical shape 121 is convex on the light incident side in the cross section shown in FIG. 2 and has three surfaces. These three surfaces are referred to as a first surface 122, a second surface 123, and a third surface 124 in order from the top in the Y direction (in order of distance from the image source LS). The second surface 123 is positioned closest to the light incident side (light incident surface side) in the Z direction (thickness direction), and faces both sides of the second surface 123 in the arrangement direction (Y direction) of the unit optical shapes 121. A first surface 122 and a second surface 123 are formed so as to be aligned.
Each of the first surface 122, the second surface 123, and the third surface 124 is a rough surface having fine irregularities on its surface. The fine irregularities are irregular in height and distribution.

It is preferable that the width of one concave or convex portion of the fine concave-convex shape is about 0.01 mm to 0.1 mm. If the width of one concave or convex portion is smaller than this range, the width of one concave or convex portion will be close to the wavelength of visible light, and the light diffusion effect due to the concave and convex shape will be reduced, and a sufficient diffusion effect will not be obtained. . Further, when the size is larger than this range, the viewer who views the image can easily recognize the minute uneven shape. Therefore, it is preferable that the width of one concave or convex portion of the fine concave-convex shape is within the above range.

In the cross section shown in FIG. 2, the first plane 122, the second plane 123, and the third plane 124 form the following angles.
First, the first surface 122 and the second surface 123 form an angle θ1. Also, the first surface 122 forms an angle θ2 with the normal direction of the screen surface. Also, the second surface 123 and the third surface 124 form an angle θ3. Also, the third surface 124 forms an angle θ4 with the normal direction of the screen surface.

The arrangement pitch of the unit optical shapes 121 is P, and the width of the unit optical shapes 121 (dimension in the arrangement direction of the end on the light output side) is W. In addition, the height of the unit optical shape 121 (dimension in the thickness direction from the point closest to the light output side of the valley bottom between the unit optical shapes 121 to the point closest to the light incident side of the unit optical shape 121) is h. be.
This unit optical shape 121 is preferably invisible to an observer. Therefore, the arrangement pitch P in the arrangement direction of the unit optical shapes 121 and the width W of the unit optical shapes 121 are preferably about 0.05 mm to 0.2 mm, and the height h is about 0.1 to 0.5 mm. It is preferable to
If the arrangement pitch P, the width W, and the height h are larger than these ranges, the unit optical shape 121 will be visually recognized as streaks by the observer O1. If the array pitch P, width W, and height h are smaller than these ranges, it may be difficult to form the screen, or sufficient optical performance as a screen may not be obtained. Therefore, the array pitch P, width W, and height h preferably satisfy these ranges.

The angles θ1 and θ2, the arrangement pitch P, and the like are determined by the projection angle of the image light L from the image source LS (the incident angle of the image light L onto the screen 10), the size of the pixels of the image source LS, and the screen 10. can be set according to the screen size, the refractive index of each layer, and the like.
For easy understanding, FIG. 2 shows an example in which the arrangement pitch P and the angles θ1 to θ4 of the unit optical shapes 121 are constant in the arrangement direction (Y direction) of the unit optical shapes 121. FIG. However, in the present embodiment, the unit optical shapes 121 have a constant arrangement pitch P and angles θ3 and θ4, but as they go upward (+Y side) in the arrangement direction (Y direction) of the unit optical shapes 121 (that is, The angle .theta.2 gradually increases with increasing distance from the image source LS. Thereby, the image light can be efficiently directed to the observer O1 on the light exit side in accordance with the change in the incident angle of the image light to the screen 10 .
It should be noted that, without being limited to this, for example, along the arrangement direction of the unit optical shapes 121, the arrangement pitch P may change, or the angle θ2 may be constant.

The optical shape layer 12 can be formed using UV curable resins such as urethane acrylate, polyester acrylate, epoxy acrylate, polyether acrylate, polythiol, and butadiene acrylate, which have high light transmittance.
In the present embodiment, an ultraviolet curable resin will be described as an example of the resin forming the optically shaped layer 12. However, the present invention is not limited to this, and other ionizing radiation curable resins such as electron beam curable resins may be used. You may form with resin.
From the viewpoint of reducing interface reflection of image light and increasing the brightness of the image displayed on the screen 10, it is preferable that there is no refractive index difference between the base material layer 11 and the optical shape layer 12. FIG. In this embodiment, the substrate layer 11 and the optical shape layer 12 have the same refractive index.

The reflective layer 13 is a semi-transmissive reflective layer that reflects part of the incident light and transmits at least part of the other incident light, and is a so-called half mirror. The reflective layer 13 of this embodiment is formed by laminating a first surface 122 , a second surface 123 and a third surface 124 on the light incident side (−Z side) of the unit optical shape 121 . The reflective layers 13 formed on the first surface 122, the second surface 123, and the third surface 124 are referred to as a first reflective portion 132, a second reflective portion 133, and a third reflective portion 134, respectively.
As described above, the first surface 122, the second surface 123, and the third surface 124 are rough surfaces having fine irregularities, and the reflective layer 13 is formed following the surface shape of each surface. The film is formed in a state in which the fine irregularities are maintained. Therefore, the surface of the reflective layer 13 on the side of the optically shaped layer 12 (light exit side) and the surface of the flattening layer 14 (light entrance side) have fine irregularities.
The reflective layer 13 diffuses and reflects a part of the incident light by means of fine unevenness. In addition, the reflective layer 13 transmits at least part of other incident light without diffusing it.

The reflective layer 13 is formed by vapor-depositing a highly light-reflective metal such as aluminum, silver, or nickel, or by sputtering a highly light-reflective metal. Also, the reflective layer 13 may be formed of a dielectric single layer or dielectric multilayer film that has high transparency, low light absorption loss, and high reflectance.
The reflective layer 13 of this embodiment is formed by vapor-depositing aluminum on the light incident side surface of the optical shape layer 12 .

The light absorbing portion 15 is positioned closer to the light incident side than the reflective layer 13 and has the function of absorbing light. The light absorbing portion 15 of this embodiment is provided so as to fill the valley between the unit optical shapes 121, as shown in FIG.
The light absorbing portion 15 of the present embodiment is made of an ultraviolet curable resin containing a black pigment, which is a microbead (average particle size of about 6 μm) that absorbs light. It is formed by filling between the optical shapes 121 and curing by irradiation with ultraviolet rays. Note that the light absorbing portion 15 is not limited to this, and may contain carbon black or the like having a function of absorbing light, or a thermosetting resin or the like as a base material containing a light absorbing material. may be used.

Although the light-absorbing microbeads used in the light absorbing portion 15 in this embodiment have an average particle size of about 6 μm, the average particle size of the microbeads is preferably about 1 to 10 μm. If the average particle diameter of the microbeads is smaller than this range, it will be difficult to scrape off the microbeads by wiping, making it difficult to form the light absorbing portion 15 . Further, if the average particle diameter of the fine beads is larger than this range, it becomes difficult to fill the valleys between the unit optical shapes 121 with the material forming the light absorbing portions 15, and the light absorbing portions 15 cannot be formed. It is from.
The refractive index of the light absorbing portion 15 is not particularly limited, and may be the same as or different from that of the optically shaped layer 12 . In this embodiment, the refractive index of the light absorbing portion 15 is the same as the refractive index of the optical shape layer 12 .

By providing such a light absorbing portion 15, it is possible to absorb part of the image light emitted upward from the screen 10, and to reduce vague reflection of the image light on the ceiling or the like.

The planarization layer 14 is a layer having optical transparency provided on the light incident side (−Z side) of the optical shape layer 12 and the reflection layer 13 .
The flattening layer 14 is a layer that covers minute irregularities caused by the unit optical shapes 121, the reflecting layer 13, the light absorbing portion 15, and the like, and flattens the surface of the screen 10 on the light incident side.

The refractive index of the flattening layer 14 is preferably equal to or substantially equal to the refractive index of the optically shaped layer 12 (the refractive index difference is small enough to be regarded as equal). Further, although the planarizing layer 14 is preferably formed using the same material as the optically shaped layer 12, it may be formed using a different material as long as it has the refractive index as described above.
The planarizing layer 14 of the present embodiment is made of the same material (ultraviolet curable resin) as the optically shaped layer 12 and has the same refractive index as the optically shaped layer 12 .

By providing such a flattening layer 14, the transparency of the screen 10 can be improved, and the reflective layer 13, which is a thin film, can be protected from damage and deterioration such as oxidation. and prevent it from falling off.
Further, by providing the flattening layer 14, for example, when a support plate (not shown) is provided on the light incident side of the screen 10, bonding to the support plate is facilitated. Further, by providing the planarization layer 14, it becomes easier to stack other layers (such as a functional layer having a function of suppressing reflection, etc.) on the light incident side.

As described above, the screen 10 of the present embodiment does not include a light diffusion layer containing diffusion materials such as particles that diffuse light due to a refractive index difference or the like. (see FIG. 1) is diffusely reflected by the reflective layer 13 and emitted to the light output side (+Z side).

Here, the angles θ1 to θ4 of the unit optical shape 121 will be explained.
In the cross section shown in FIG. 2, the angle θ2 formed by the first surface 122 with the normal direction (Z direction) of the screen surface is the angle θ2 of the image light projected onto the screen 10 from the image source LS located below the light incident side. It is preferable that the angle is 5° or more and 20° or less (5°≦θ2≦20°) so as to face the viewer O1 (see FIG. 1) positioned in front of the screen 10 on the light exit side.
When the angle θ2 becomes larger or smaller than this range, the image light reflected by the first reflecting portion 132 is emitted in a direction outside the observable area for the observer O1, and the visibility of the image is deteriorated.
The angle θ2 may be appropriately selected and set within this range according to the incident angle of the image light and the refractive indices of the optical shape layer 12 and the planarization layer 14 . In the present embodiment, the angle θ2 changes upward along the arrangement direction of the unit optical shapes 121 while satisfying this range.

Next, in this embodiment, in the cross section shown in FIG. 2, the angle θ4 formed by the third surface 124 with the normal direction of the screen surface is smaller than the angle θ2.
Next, in this embodiment, in the cross section shown in FIG. 2, the second surface 123 is parallel to the screen surface. By adopting such a form, the light absorbing portion 15 can be easily formed by wiping (soothing) or the like during the manufacture of the screen, and the productivity of the screen 10 can be improved.

Next, an example of a method for manufacturing the screen 10 of this embodiment will be described.
First, the base material layer 11 is prepared, and on one surface thereof, a molding die for shaping the unit optical shape 121 is laminated with an ultraviolet curing resin filled therein, and UV molding is performed by irradiating ultraviolet rays to cure the resin. The optical shape layer 12 is formed by a method. At this time, the substrate layer 11 may be in the form of a sheet or may be in the form of a web.
The surfaces for forming the first surface 122, the second surface 123, and the third surface 124 of the molding die for shaping the unit optical shape 121 have fine irregularities on their surfaces. This uneven shape is formed by sandblasting, wet blasting, etching, or the like. By forming the fine irregularities on the surface of the unit optical shape 121 with a molding die, even when manufacturing a large number of screens 10, the individual screens 10 can be stably manufactured with little variation in quality.

After forming the optical shape layer 12 on one surface of the base material layer 11 , the reflective layer 13 is formed on the surface of the unit optical shape 121 . In this embodiment, the reflective layer 13 is formed by depositing aluminum.
After that, an ultraviolet curable resin containing a black pigment is applied from above the reflective layer 13 so as to fill the valleys between the unit optical shapes 121 , and is wiped (squeegeeed) onto the second reflective portion 133 . The ultraviolet curable resin containing the black pigment is removed and then cured by irradiating with ultraviolet rays to form the light absorbing portion 15 .
Next, an ultraviolet curable resin is applied on the surface composed of the light absorbing portion 15 and the reflective layer 13 (second reflecting portion 133) to flatten the surface, and the ultraviolet curable resin is cured by irradiating ultraviolet rays. to form the planarization layer 14 . After that, the screen 10 is completed by cutting to a predetermined size.

Next, the states of image light and external light incident on the screen 10 of this embodiment will be described.
FIG. 3 is a diagram for explaining how image light and external light enter the screen 10 of the first embodiment. In FIG. 3, the interface between the base material layer 11 and the optical shape layer 12 is omitted for easy understanding.
As shown in FIG. 3, part of the image light L1 (image light L2) projected from the image source LS positioned below (−Y side) and incident on the screen 10 is formed on the second surface 123. The light is transmitted through the second reflecting portion 133, diffusely reflected by the first reflecting portion 132 formed on the first surface 122, and is reflected by the observer O1 (see FIG. ) emits an image in a visible direction. Thereby, the observer O1 can observe the image displayed on the screen 10 .

A portion of the image light L1 (image light L3) is reflected by the second reflecting portion 133 formed on the second surface 123 and emitted from the screen 10 upward on the light incident side (−Z side). Since the image light L3 is directed upward and does not reach the observer O1, it does not hinder the observer O1 from viewing the image.
Also, part of the image light L<b>1 that has passed through the second reflecting portion 133 (image light L<b>4 ) passes through the first reflecting portion 132 and is absorbed by the light absorbing portion 15 . Therefore, it is possible to suppress the image light directed toward the ceiling or the like on the light exit side indicated by the dashed line in FIG. 3, and reduce the reflection of the image light on the ceiling or the like on the light exit side.

Next, external light other than the image light incident on the screen 10, such as sunlight and illumination light, will be described.
In the cross section shown in FIG. 3, some of the external light G1 and G2 incident on the screen 10 at a small incident angle is reflected by the second reflecting section 133 (not shown), but most of it is transmitted through the second reflecting section 133. and emitted from the screen 10 .
The screen 10 does not have a light diffusion layer containing diffusion particles or the like for diffusing light, and the reflection layer 13 does not diffuse the transmitted light. The transmitted external light G1, G2 is not diffused. Therefore, when an observer observes the scenery on the other side through the screen 10 from the light incident side and the light emitting side, the scenery on the other side of the screen 10 is less likely to be blurred or blurred. . Therefore, the screen 10 can have high transparency.

Next, external light incident on the screen 10 from above at a large angle of incidence will be described.
External light G3 that enters the screen 10 at a large angle of incidence from above the light exit side (+Z side) enters the third reflecting portion 134 formed on the third surface 124 . Part of the external light G3 (external light G4) is reflected by the third reflecting portion 134 toward the second reflecting portion 133 formed on the second surface 123, passes through the second reflecting portion 133, and enters the light. side upwards. Part of the external light G3 (external light G5) is transmitted through the third reflecting section 134 and absorbed by the light absorbing section 15 . Part of the external light G3 reflected by the third reflecting unit 134 (external light G6) is reflected by the first reflecting unit 132 and emitted downward on the light exit side of the screen 10, Light G7) passes through the first reflecting portion 132 and is absorbed by the light absorbing portion 15 .

External light G8 that is incident on the screen 10 at a large incident angle from above the light incident side (−Z side) is incident on the second reflecting portion 133 formed on the second surface 123 . Part of the external light G8 (external light G9) is reflected by the second reflecting section 133 and emitted downward on the light incident side of the screen 10 . Part of the external light G8 (external light G11) passes through the second reflecting section 133, is reflected by the third reflecting section 134 formed on the third surface 124, and travels upward on the light entrance side of the screen 10. emit. Part of the external light G8 (external light G10) is transmitted through the third reflecting section 134 and absorbed by the light absorbing section 15 .

In addition, although not shown, part of the external light repeats reflection on the reflective layer 13 and total reflection on the interface between the screen 10 and the air, and is gradually attenuated within the screen 10 or repeatedly reflected. The light enters the light absorbing portion 15 and is absorbed.
Therefore, most of the external light that enters the screen 10 at a large incident angle, such as illumination light and sunlight, does not reach the observer O1, thereby suppressing deterioration in image contrast due to external light, reflection of external light, and the like. can.

Conventional transmissive screens are designed to have very low transparency so that the image source side cannot be seen through the screen, and the scenery on the other side cannot be seen through the screen.
In addition, conventional transmissive screens are often provided with a light diffusion layer or the like containing diffusion particles or the like for diffusing light, in order to provide an image with a sufficient viewing angle. Therefore, even if the transparency of other layers is improved, the diffuser particles in the light diffusion layer also diffuse the external light, so the scenery on the other side of the screen is blurred or whitish, which is observed by the viewer. There is a problem that

However, the screen 10 of this embodiment does not have a light diffusing layer containing diffusing particles and the like as described above. Further, in the screen 10 of the present embodiment, the reflective layer 13 has a rough surface having fine irregularities on both sides thereof, and the image light is diffused when reflected by the reflective layer 13, but is transmitted through the reflective layer 13. The light (image light and ambient light) that is emitted is not diffused.
Therefore, according to the present embodiment, the screen 10 can display an image with good viewing angle, brightness, and resolution to the observer O1 positioned in front of the screen 10 on the light exit side (+Z side), and Even in an environment where there is a lot of external light, such as when no light is projected, the scenery on the other side of the screen 10 does not blur white or blur, and is well visible to the observer O1, and has high transparency. realizable.

Further, according to the present embodiment, since the screen 10 has high transparency as described above, an observer on the light incident side (-Z side) of the screen 10 can Also, the scenery on the light output side (+Z side) can be visually recognized well through the screen 10 .
Furthermore, according to the present embodiment, even when the image light is projected onto the screen 10, the viewers on the light entrance side and the light exit side of the screen cannot see through the screen 10 in the portion where the brightness of the image light is low. A part of the scenery on the side can be visually recognized, and high transparency of the screen 10 can be realized.

Further, according to the present embodiment, since the screen 10 includes the light absorbing portion 15, the light absorbing portion 15 absorbs the image light that passes through the first reflecting portion 132 and travels toward the ceiling or the like on the light exit side. can effectively reduce unnecessary reflection of image light formed on the ceiling or the like on the light exit side. As a result, the observer O1 can comfortably view the image, and the comfort of the space in which the image is displayed can be improved.
Moreover, according to the present embodiment, since the light absorbing portion 15 is provided, unnecessary external light is absorbed, and the contrast of the image displayed on the screen 10 is improved. Therefore, the screen 10 and the image display device 1 can provide clearer images.

Further, in the present embodiment, the unit optical shape 121 has a quadrangular prism shape with a substantially quadrangular cross section. Therefore, the reflective layer 13 can be easily formed, and the light absorbing portion 15 can be easily formed by wiping (squeegeeing) or the like. Therefore, according to this embodiment, the screen 10 can be easily manufactured, and the screen 10 can be mass-produced at low cost.

(Second embodiment)
FIG. 4 is a diagram for explaining the screen 20 of the second embodiment. In FIG. 4, a part of the cross section along the plane parallel to the YZ plane passing through the screen center of the screen 20 of the second embodiment (the point corresponding to the point A of the screen 10 of the first embodiment shown in FIG. 1) is enlarged. is shown.
In the screen 20 of the second embodiment, the second surface 123 of the unit optical shape 221 is inclined with respect to the screen surface, and the upper end 123a is positioned closer to the light entrance side than the lower end 123b. The screen 10 differs from the screen 10 of the first embodiment in that it is slanted, but otherwise is the same as the screen 10 of the first embodiment. Therefore, in the second embodiment described below, portions that perform the same functions as those of the first embodiment described above are denoted by the same reference numerals or the same reference numerals at the end thereof, and overlapping descriptions are omitted as appropriate. In the third embodiment and the fourth embodiment described later, portions that perform the same functions as in the first embodiment described above are denoted by the same reference numerals or the same reference numerals at the end thereof, so as to avoid overlapping explanations. Omit as appropriate.

The screen 20 is a transmissive screen having a substrate layer 11, an optical shape layer 12, a reflective layer 13, a light absorbing portion 15, and a flattening layer 14 in order from the light exit side (+Z side). This screen 20 can be applied to the video display device 1 of the first embodiment described above.
In this screen 20, the second surface 123 of the unit optical shape 221 is inclined with respect to the screen surface, and in the cross section shown in FIG. It is located on the light incident side (-Z side) of the end portion 123b. That is, the second surface 123 is inclined in the direction in which the unit optical shapes 221 are arranged so that the end on the side farther from the image source LS is located on the light incident side.

In the cross section of the screen 20 shown in FIG. 4, the light incident side (−Z side) surface of the light absorbing portion 15 has a lower (−Y side) edge in the vertical direction and an upper (+Y side) edge. It is inclined so as to be closer to the light incident side than the part.
The light absorbing portion 15 of this embodiment can also be produced by wiping (squeegeeing) an ultraviolet curable resin or the like containing a black pigment having a light absorbing property, as in the first embodiment described above. can.

By adopting such a configuration, as shown in FIG. 4, part of the image light L5 incident on the screen 20 (image light L6) passes through the second reflection section 133 and is diffused by the first reflection section 132. The light is reflected and emitted to an area visible to the observer O1 on the light emitting side. In addition, part of the image light L5 (image light L7) transmitted through the first reflecting portion 132 is absorbed by the light absorbing portion 15, so that reflection of the image light on the ceiling or the like on the light entrance side is reduced. .
Part of the image light L5 (image light L8) incident on the screen 20 is diffusely reflected by the second reflecting section 133 and emitted toward the observer O2 positioned in the front direction on the light incident side of the screen 20. . As a result, reflection of image light formed on the ceiling or the like on the light incident side can also be reduced. Further, as a result, even though the image is horizontally reversed, the observer O2 positioned on the light incident side can also observe the image.

From the viewpoint of reducing unnecessary reflection of image light formed on the ceiling or the like on the light entrance side and displaying an image to the observer O2 positioned in the front direction on the light entrance side, the angle θ1 is set to 85 ° or more and less than 95° (85°≤θ1<95°), most preferably 90°. The angle θ1 in this embodiment is 90° (θ1=90°).
When the angle θ1 is 90°, the image is most efficiently directed toward the observer O2 positioned in front of the light incident side while reducing unnecessary reflection of the image light formed on the ceiling or the like on the light incident side. can be reflected.
In addition, when the angle θ1 is not 90° but satisfies 85°≦θ1<95°, the brightness of the image is reduced to about half of that when θ1=90°, but the observer O2 visually recognizes the image. can. Also in this case, the effect of reducing unnecessary reflection of image light formed on the ceiling or the like on the light incident side can be sufficiently obtained.

From the above, according to this embodiment, in addition to the effects of improving the transparency of the screen 20, improving the contrast of the image, and reducing the reflection of image light that occurs on the ceiling on the light exit side, etc. In addition, the viewer O2 positioned on the light incident side can also receive an image even though the image is left-right reversed.
Although FIG. 4 shows an example in which the angle θ1 is constant along the arrangement direction of the unit optical shapes 221, the angle θ1 is not limited to this, and the angle θ1 is continuously changed according to the incident angle of the image light. Alternatively, it may be changed stepwise. By adopting such a form, reflection of unnecessary image light formed on the ceiling or the like on the light entrance side can be more effectively reduced, and the observer O2 positioned on the light entrance side can also be provided with an image. .

(Third embodiment)
FIG. 5 is a diagram for explaining the screen 30 of the third embodiment. In FIG. 5, a part of the cross section along the plane parallel to the YZ plane passing through the screen center of the screen 30 of the third embodiment (the point corresponding to the point A of the screen 10 of the first embodiment shown in FIG. 1) is enlarged. is shown.
The second surface 123 of the screen 30 of the third embodiment is inclined, and the lower end 123b of the second surface 123 is positioned closer to the light incident side than the upper end 123a. Although different from the screen 10 of the first embodiment, other aspects are the same as the screen 10 of the first embodiment.

The screen 30 is a transmissive screen having a substrate layer 11, an optical shape layer 12, a reflective layer 13, a light absorbing portion 15, and a flattening layer 14 in order from the light exit side (+Z side). This screen 30 can be applied to the video display device 1 of the first embodiment described above.
In this screen 30, the second surface 123 of the unit optical shape 321 is inclined with respect to the screen surface, and in the cross section shown in FIG. It is located on the light incident side (-Z side) of the end portion 123a. That is, the second surface 123 is inclined in the direction in which the unit optical shapes 321 are arranged so that the end closer to the image source LS is located on the light incident side.

In the cross-section of the screen 30 shown in FIG. 5, the light-incident surface of the light-absorbing portion 15 is such that the upper (+Y side) end portion in the vertical direction receives more light than the lower (−Y side) end portion. It is slanted to the side.
The light absorbing portion 15 of the present embodiment can also be produced by wiping (squeegeeing) an ultraviolet curable resin containing a black pigment or the like having a light absorbing property, as in the first embodiment described above. can.

In the cross section of the screen 30 shown in FIG. 5, part of the image light L9 incident on the screen 30 (image light L10) is transmitted through the second reflection portion 133 of the second surface 123, and is reflected by the first reflection portion 132. The light is diffusely reflected and emitted to an area visible to the observer O1 on the light emitting side. Also, part of the image light L9 (image light L11) is transmitted through the first reflection section 132 and absorbed by the light absorption section 15 . As a result, unnecessary image light emitted upward on the light exit side of the screen 10 is reduced, and unnecessary reflection of the image light on the ceiling or the like on the light exit side is reduced. Also, as shown in FIG. 5 , part of the image light L9 (image light L12) is reflected by the second reflecting section 133 .

Here, in the screen 30, when the refractive index of the layer located closest to the light incident surface side and forming the interface with the air is n, the first surface 122 and the second surface in the cross section shown in FIG. 123 satisfies the following expression, the image light L12 reflected by the second reflecting portion 133 is emitted upward on the light incident side and is reflected on the ceiling or the like to form a region of light. can be reduced significantly. In this embodiment, n is the refractive index of the planarization layer 14, and the angle θ1 satisfies the following formula.
1/2×arcsin(1/n)+103°≦θ1≦1/2×arcsin(1/n)+107°

Since the above formula is satisfied, as shown in FIG. 5, the image light L12 is reflected by the second reflecting section 133, then totally reflected by the interface between the flattening layer 14 and the air, and travels upward in the screen 30. Reflection on the reflective layer 13 and total reflection on the air interface are repeated, and the light is gradually attenuated. As a result, it is possible to reduce unnecessary reflection of the image light caused by the image light being reflected by the second reflecting section 133 and generated on the ceiling or the like above the light incident side.
Also, from the viewpoint of reducing unnecessary reflection of image light on the ceiling or the like, it is most preferable that the angle θ1 satisfies the following formula.
θ1=1/2×arcsin(1/n)+105°

Therefore, according to the present embodiment, in addition to the effects of improving the transparency of the screen 30, improving the contrast of the image, and reducing unnecessary reflection of image light that occurs on the ceiling on the light exit side, etc., the ceiling on the light entrance side It is possible to obtain the effect of being able to reduce reflection of unnecessary image light that is formed.
Although FIG. 5 shows an example in which the angle θ1 is constant along the arrangement direction of the unit optical shapes 321, the angle θ1 is not limited to this, and the angle θ1 is continuously changed according to the incident angle of the image light. Alternatively, it may be changed stepwise. By adopting such a configuration, reflection of unnecessary image light formed on the ceiling or the like on the light entrance side can be more effectively reduced.

(Fourth embodiment)
FIG. 6 is a diagram for explaining the screen 40 of the fourth embodiment. In FIG. 6, a part of the cross section along the plane parallel to the YZ plane passing through the screen center of the screen 40 of the fourth embodiment (the point corresponding to the point A of the screen 10 of the first embodiment shown in FIG. 1) is enlarged. is shown.
The screen 40 of the fourth embodiment is different from the screen 10 of the first embodiment in that the light absorbing portion 45 is film-like, but otherwise is the same as the screen 10 of the first embodiment.

The screen 40 is a transmissive screen that includes a substrate layer 11, an optical shape layer 12, a reflective layer 13, a light absorbing portion 45, and a flattening layer 14 in order from the light output side (+Z side). This screen 40 can be applied to the video display device 1 of the first embodiment described above.
As shown in FIG. 6, the light absorbing portion 45 is formed on the reflecting layer 13 (the first reflecting portion 132 and the third reflecting portion 134) formed on the first surface 122 and the third surface 124 of the unit optical shape 121. It is formed like a film along the The light absorbing portion 45 is not formed in the second reflecting portion 133 .
As a result, valleys between the unit optical shapes 121 are filled with the flattening layer 14 .
Such a light absorbing portion 45 is formed by, for example, masking only the second reflecting portion 133 with PVA (polyvinyl alcohol), vapor-depositing silver, bismuth, or the like in a low-pressure environment, and removing the PVA masking. be.

Such a light absorbing portion 45 can also absorb unnecessary image light directed upward on the light exit side of the screen 40, and can reduce reflection of the image light on the ceiling or the like on the light exit side.
Therefore, according to the present embodiment, similar to the first embodiment, it is possible to improve the transparency of the screen 40, improve the contrast of the image, and reduce unnecessary reflection of image light on the ceiling on the light exit side. be done.

(deformed form)
Various modifications and changes are possible without being limited to the embodiments described above, and they are also within the scope of the present invention.
(1) In each embodiment, an example in which the reflective layer 13 is formed on the first surface 122, the second surface 123, and the third surface 124 is shown. It may be formed only on the first surface 122 or may be formed only on the first surface 122 and the second surface 123 . That is, the screens 10, 20, 30, and 40 may have a form in which the reflection layer 13 is not formed on the third surface 124 (the third reflection section 134 is not provided).
By adopting such a configuration, the amount of light that passes through the screen increases, and the transparency of the screen can be further improved.

When the reflective layer 13 is not formed on the third surface 124, the angle θ4 formed by the third surface 124 with the normal direction of the screen is 0°, that is, the third surface 124 is orthogonal to the screen surface. preferably. By setting the angle θ4 at or near 0°, it becomes difficult for a reflective layer formed by vapor deposition or the like to be formed on the third surface 124, so that a screen without the third reflecting section 134 can be easily manufactured. .

(2) In each of the embodiments, the unit optical shapes 121, 221, and 321 have shown the examples in which they are quadrangular prisms, but the present invention is not limited to this, and may be truncated quadrangular pyramids that are parallel to the screen surface and intersect each other. It may be arranged in two directions (including orthogonal).
Also, the unit optical shapes 121, 221, 321 may be arranged concentrically with their centers in a plane parallel to the screen surface. At this time, the center of the concentric circle may be located within the screen when viewed from the normal direction of the screen surface, or may be located outside the screen (below the outside of the screen in each of the above-described embodiments). good too.

(3) In each embodiment, the screens 10, 20, 30, and 40 are arranged on the light exit side (+Z side) of the base material layer 11 and the light entrance side (−Z side) of the flattening layer 14. A functional layer (not shown) having a function of protecting 30 and 40 may be provided.
Functions of such a functional layer include, for example, a hard coat function to prevent scratches, an antireflection function, an ultraviolet absorption function, an antifouling function, an antistatic function, and the like. The functional layer may have one function or a plurality of functions. Moreover, the functional layer may be a single layer, or may have a form in which a plurality of layers are laminated.

For example, by providing a functional layer having an antireflection function on the light incident side of the planarization layer 14, reflection of image light when it enters the screen can be suppressed, and the amount of incident light can be increased. Further, when a functional layer having an antireflection function is provided on the light exit side of the base material layer 11, part of the image light is reflected by the surface of the screen on the light exit side and emitted from the light entrance side. It is also possible to prevent a part of the image from being seen by an observer on the light side.
Furthermore, a functional layer having a touch panel function may be provided on the light exit side (+Z side) of the screens 10, 20, 30, and 40. FIG.

(4) In each embodiment, the image source LS is arranged vertically below the screens 10, 20, 30, and 40, but is not limited to this, and may be arranged above the screens in the vertical direction. Alternatively, the image light may be projected obliquely onto the screen positioned below. The screens in this case have a form in which the vertical direction (Y direction) of the screens 10, 20, 30, and 40 in each of the above-described embodiments is reversed.
In this manner, the position of the image source LS can be appropriately selected and arranged according to the usage environment of the image display device 1 .
In this case, according to this modification, it is possible to reduce reflection of image light on the floor rather than on the ceiling.

(5) In each embodiment, the unit optical shapes 121, 221, 321 are adjacent in the arrangement direction, but not limited to this, for example, the unit optical shapes are arranged at intervals, A configuration in which the arrangement pitch P is larger than the width W may be employed.

Although the present embodiment and modifications can be used in combination as appropriate, detailed description thereof will be omitted. Moreover, the present invention is not limited to each embodiment described above.

1 image display device 10, 20, 30, 40 screen 11 substrate 12 optical shape layer 121, 221, 321 unit optical shape 122 first surface 123 second surface 124 third surface 13 reflective layer 132 first reflective portion 133 Second Reflector 134 Third Reflector 14 Flattening Layer 15, 45 Light Absorber LS Image Source

Claims (10)

A transmissive screen that transmits and displays at least part of image light,
a plurality of unit optical shapes located inside the transmissive screen, convex toward a light incident surface on which image light is incident, and arranged along at least a first direction parallel to the screen surface;
It is laminated in the form of a film on the light incident surface side of the unit optical shape, transmits part of the image light incident from the light incident surface, reflects part of the image light incident from the light incident surface, and forwards a reflective layer directed toward a light exit surface facing the light entry surface;
a light absorbing portion that is formed between the arranged adjacent unit optical shapes and absorbs light;
with
The unit optical shape has a substantially rectangular cross-sectional shape in a cross section parallel to the first direction and the thickness direction of the transmissive screen. Of the two opposing surfaces located on both sides of the second surface in the first direction, the one forming a larger angle with the normal direction of the screen surface is defined as the first surface, and the smaller one is defined as the third surface,
The reflective layer is formed on at least the first surface and the second surface;
A transmissive screen characterized by In the transmissive screen according to claim 1,
the reflective layer has an uneven shape on its surface and diffusely reflects a part of incident light;
A transmissive screen characterized by In the transmissive screen according to claim 1 or claim 2,
an angle θ2 formed between the first surface and the normal direction of the screen surface is 5° or more and 20° or less;
A transmissive screen characterized by In the transmissive screen according to any one of claims 1 to 3,
wherein the light absorbing portion is formed to fill valleys between the unit optical shapes;
A transmissive screen characterized by In the transmissive screen according to any one of claims 1 to 4,
the second surface being parallel to the screen surface of the transmissive screen;
A transmissive screen characterized by In the transmissive screen according to any one of claims 1 to 4,
the second surface is inclined such that the end on the first surface side is positioned closer to the light incident surface than the end on the third surface side;
A transmissive screen characterized by In the transmissive screen according to claim 6,
an angle θ1 formed by the first surface and the second surface is 85° or more and less than 95°;
A transmissive screen characterized by In the transmissive screen according to any one of claims 1 to 4,
the second surface is inclined such that the end on the side of the third surface is located closer to the light incident surface than the end on the side of the first surface;
A transmissive screen characterized by In the transmissive screen according to claim 8,
The angle θ1 formed by the first surface and the second surface is defined by n, which is the refractive index of the layer located closest to the light incident surface in the thickness direction of the transmissive screen and forming an interface with air. when
1/2×arcsin(1/n)+103°≦θ1≦1/2×arcsin(1/n)+107°
satisfying the expression
A transmissive screen characterized by a transmissive screen according to any one of claims 1 to 9;
an image source that projects image light onto the transmissive screen;
A video display device.

Images