JP2020134677A - Reflection screen, optical member and image display device - Google Patents

Abstract

To more efficiently and inexpensively manufacture: a reflection screen high in transparency and capable of displaying an excellent image; an optical member; and an image display device.SOLUTION: A reflection screen 10 for reflecting image light projected from an image source LS to display an image, comprises: a plurality of optical shape layers 12 having light transmissivity and having a unit optical shape 121 having a first surface 121a having incident image light and a second surface 121b opposite thereto and arranged on a surface on the rear surface side; and a reflective layer 13 formed in a part of at least the first surface 121a of the unit optical shape 121. The unit optical shape 121 has a fine and irregular uneven shape on the surface thereof; the surface of the reflective layer 13 on the unit optical shape side has an uneven shape corresponding to the uneven shape; and the reflective layer 13 reflecting a part of incident light has a function transmitting the other light and is formed of a single layer dielectric film.SELECTED DRAWING: Figure 2

Description

The present invention relates to a reflective screen, an optical member, and an image display device.

Conventionally, various reflective screens have been developed that reflect and display the image light projected from the image source (see, for example, Patent Document 1). In particular, it can be used as a reflective screen that projects image light so that the image can be seen well by attaching it to a highly translucent member such as window glass, and when not in use, it does not project image light. Demand for semi-transmissive reflective screens, which allow the scenery on the other side of the screen to be seen through, is increasing due to its high design.

Japanese Unexamined Patent Publication No. 9-114003

However, if such a semi-transmissive reflective screen is provided with a diffusion layer containing diffuse particles or the like, the scenery on the other side of the screen may be observed whitish and blurred, resulting in deterioration of design. Therefore, improvement of transparency has been an issue. In addition, it is always required to reduce the thickness of various screens and display good images with high contrast.
The above-mentioned Patent Document 1 proposes a screen that can be used for both a transmissive type and a reflective type, and can transmit light from the back surface side. However, Patent Document 1 does not disclose any measures for improving transparency.
Here, in order to improve the transparency of the transflective reflective screen and display a good image, it is possible to use a dielectric multilayer film in which a plurality of dielectric films are laminated on a reflective layer that reflects image light. Conceivable. However, when a dielectric multilayer film is used as the reflective layer, some of the dielectric films may be damaged in the manufacturing process of the dielectric multilayer film, and it becomes difficult to form an appropriate dielectric multilayer film. In some cases,

An object of the present invention is to manufacture a reflective screen, an optical member, and an image display device having high transparency and capable of displaying a good image more efficiently and inexpensively.

The present invention solves the above-mentioned problems by the following solutions. In addition, in order to facilitate understanding, the description will be given with reference numerals corresponding to the embodiments of the present invention, but the description is not limited thereto.
The first invention is a reflective screen that reflects an image light (L) projected from an image source and displays an image, has light transmission, and has a first surface (121a,) on which the image light is incident. A unit optical shape (121,221) having a 221a) and a second surface (121b, 221b) facing the 221a) is an optical shape layer (12, 22) in which a plurality of units are arranged on the back surface side, and the unit. The unit optical shape includes a reflective layer (13) formed on at least a part of the first surface of the optical shape, and the unit optical shape has a fine and irregular uneven shape on the surface of the reflective layer. The surface on the unit optical shape side has a concavo-convex shape corresponding to the concavo-convex shape, and the reflective layer has a function of reflecting a part of the incident light and transmitting the other, and is a single layer dielectric. It is a reflective screen (10, 20) characterized by being formed by a body membrane.
The second invention is the reflective screen (10, 20) of the first invention, wherein the dielectric film has a film thickness of 30 nm or more and 100 nm or less.
The third invention states that, in the reflective screen of the first invention or the second invention, the total light transmittance of light incident on the reflective screen at an incident angle of 0 ° is 70% or more and 85% or less. It is a characteristic reflective screen (10, 20).
In the fourth invention, in any of the reflective screens from the first invention to the third invention, the diffuse reflectance of light incident on the reflective screen from the image source side at an incident angle of 0 ° is 5% or more and 35. A reflective screen (10, 20) characterized by being less than or equal to%.
A fifth invention is a reflective screen according to any one of the first to fourth inventions, wherein the peak gain of the reflective screen is 0.2 or more and 3.5 or less. (10, 20).
A sixth invention is a reflective screen (10,) characterized in that, in any of the reflective screens from the first invention to the fifth invention, the haze value of the reflective screen is 5.0% or less. 20).
According to a seventh aspect of the present invention, in any of the reflective screens from the first invention to the sixth invention, the dielectric film forming the reflective layer (13) is zinc sulfide (ZnS) and titanium oxide (TiO ₂ ). ), A reflective screen (10, 20) comprising at least one of niobium pentoxide (Nb ₂ O ₅ ).
The eighth invention is an angle from an emission angle which is the peak brightness of the reflected light of the reflection screen to an emission angle where the brightness is halved in any of the reflection screens from the first invention to the seventh invention. The reflection screen (10, 20) is characterized in that 5 ° ≦ α ≦ 30 ° when the amount of change is + α1 and −α2 and the average value of the absolute values is α.
A ninth aspect of the invention is a reflective screen (10, 20), wherein any of the reflective screens from the first invention to the eighth invention does not include a diffusion layer containing diffuse particles. ..
The tenth invention has light transmittance in any of the reflective screens from the first invention to the ninth invention, and the side on which the unit optical shape of the optical shape layer (12, 22) is formed. The reflection screen (10, 20) is provided with a second optical shape layer (14) laminated so as to fill a valley portion between the unit optical shapes on the surface of the screen.
The eleventh invention is a light-transmitting layer (14, 15) having at least one light-transmitting layer on the back surface side of the reflective layer (13) in any of the reflective screens from the first invention to the tenth invention. ) Is provided, and the area from the image source side surface of the reflection screen (10, 20) to the back surface side of the reflection layer is defined as an image source side region in the thickness direction of the reflection screen, and the image source side of the reflection layer. When the area from the surface to the back surface of the reflection screen is the back region, the absorption rate of the light in the back region with respect to the light incident from the back surface of the screen surface of the reflection screen at an incident angle of 0 degrees is the reflection. The reflective screen is characterized in that it is larger than the light absorption rate of the image source side region with respect to the light incident from the image source side of the screen surface of the screen at an incident angle of 0 degrees.
The twelfth invention includes any reflective screen (10, 20) from the first invention to the eleventh invention, a first transparent base material arranged on the image source side of the reflective screen, and the reflective screen. It is an optical member including a second transparent base material arranged on the back surface side.
A thirteenth invention is an image display device including any one of the reflective screens (10, 20) from the first invention to the eleventh invention, and an image source (LS) for projecting image light onto the reflective screen. (1).

According to the present invention, it is possible to achieve the effect that a reflective screen, an optical member, and an image display device having high transparency and capable of displaying a good image can be manufactured more efficiently and inexpensively.

It is a figure which shows the image display device 1 of 1st Embodiment. It is a figure explaining the layer structure of the screen 10 of 1st Embodiment. It is a figure which looked at the 1st optical shape layer 12 of 1st Embodiment from the back surface side (−Z side). It is a figure which shows the state of the image light and the outside light on the screen 10 of 1st Embodiment. It is a figure explaining the screen 20 of the 2nd Embodiment. It is a figure which shows the image display device 1A of a modified form. It is a figure explaining the relationship between the 1/2 angle α, the incident angle φ of the image light, and the angle θ1 of the first slope 121a.

Hereinafter, embodiments of the present invention will be described with reference to the drawings and the like. In addition, each figure shown below including FIG. 1 is a diagram schematically shown, and the size and shape of each part are exaggerated as appropriate for easy understanding.
In the present specification, terms that specify a shape or a geometric condition, for example, terms such as parallel and orthogonal, have the same optical function in addition to their strict meanings, and can be regarded as parallel or orthogonal. It shall also include the state having the error of.
In the present specification, numerical values such as dimensions of each member and material names described are examples of embodiments, and the present invention is not limited to these, and may be appropriately selected and used.
In this specification, terms such as board and sheet are used. Generally, the plates, sheets, and films are used in the order of thickness, and are used in the same manner in the present specification. However, since there is no technical meaning in such proper use, these words can be replaced as appropriate.
In the present specification, the screen surface indicates a surface in the plane direction of the screen when viewed as the entire screen, and is assumed to be parallel to the screen (display surface) of the screen.

(First Embodiment)
FIG. 1 is a diagram showing a video display device 1 of the first embodiment. FIG. 1A is a perspective view of the image display device 1, and FIG. 1B is a side view of the image display device 1.
The image display device 1 has a screen 10, an image source LS, and the like. The screen 10 of the present embodiment can reflect the image light L projected from the image source LS and display the image on the screen (display surface) on the image source side. Details of the screen 10 will be described later.
In the present embodiment, as an example, the image display device 1 is applied to the show window of a store, and the screen 10 is fixed to the glass of the show window.

Here, in order to facilitate understanding, in each of the following figures including FIG. 1, an XYZ Cartesian coordinate system is appropriately provided and shown. In this coordinate system, the horizontal direction (horizontal direction) of the screen of the screen 10 is the X direction, the vertical direction (vertical direction) is the Y direction, and the thickness direction of the screen 10 is the Z direction. The screen 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 of the screen 10.
Further, the direction toward the right side in the horizontal direction when viewed from the observer O1 located in the front direction of the image source side of the screen 10 is the + X direction, the direction toward the upper side in the vertical direction is the + Y direction, and the back side (back surface side) in the thickness direction. ) Toward the image source side is the + Z direction.
Further, in the following description, the screen vertical direction, the screen horizontal direction, and the thickness direction are the screen vertical direction (vertical direction), the screen horizontal direction (horizontal direction), and the screen vertical direction (vertical direction) in the usage state of the screen 10, unless otherwise specified. It is assumed that the thickness direction (depth direction) is parallel to the Y direction, the X direction, and the Z direction, respectively.

The image source LS is an image projection device (projector) that projects the image light L onto the screen 10. The image source LS of the present embodiment is a short focus type projector.
The image source LS is a screen 10 when the screen (display area) of the screen 10 is viewed from the front direction (normal direction of the screen surface) of the image source side (+ Z side) in the state of use of the image display device 1. It is located at the center of the screen in the left-right direction of the screen 10 on the lower side (−Y side) in the vertical direction with respect to the screen of the screen 10.
The image source LS can project the image light L diagonally from a position in the depth direction (Z direction) where the distance from the surface of the screen 10 on the image source side (+ Z side) is significantly closer than that of the conventional general-purpose projector. .. Therefore, as compared with the conventional general-purpose projector, the image source LS has a shorter projection distance to the screen 10 and a larger incident angle at which the projected image light is incident on the screen 10.

The screen 10 is a reflective screen that displays a part of the image light L projected by the image source LS toward the observer O1 side located on the image source side (+ Z side) and displays the image light. It is a translucent reflective screen having transparency that allows the scenery on the other side of the screen 10 to be observed when the screen is not used.
The screen (display area) of the screen 10 has a substantially rectangular shape in which the long side direction is the left-right direction of the screen when viewed from the observer O1 side on the image source side (+ Z side) in the used state.
The screen 10 has a large screen having a screen size of about 80 to 100 inches diagonally, and the aspect ratio of the screen is 16: 9. The size is not limited to this, and may be, for example, about 40 inches or less, and the size and shape can be appropriately selected according to the purpose of use, the environment of use, and the like.

In general, the screen 10 is a laminated body of thin layers made of resin or the like, and in many cases, the screen 10 alone does not have sufficient rigidity to maintain flatness. Therefore, as shown in FIG. 1, the screen 10 of the present embodiment is integrally joined (or partially fixed) to the support plate 50 via a bonding layer 51 having light transmission on the back surface side thereof, so that the screen has flatness. Is maintained.
The support plate 50 is a flat plate-shaped member having light transmittance and high rigidity, and a plate-shaped member made of resin such as acrylic resin or PC resin or made of glass can be used.
The support plate 50 of the present embodiment is a window glass of a show window of a store or the like. Not limited to this, the support plate 50 may be a flat partition made of transparent glass or resin, and the screen 10 has four sides and the like supported by a frame member (not shown) and its flatness. It may be in the form of maintaining.

FIG. 2 is a diagram illustrating a layer structure of the screen 10 of the first embodiment. In FIG. 2, the screen 10 passes through a point A (see FIG. 1), which is the center of the screen (geometric center of the screen) on the image source side (+ Z side) of the screen 10, and is parallel to the vertical direction (Y direction) of the screen. A part of the cross section perpendicular to the screen surface (parallel to the Z direction, which is the thickness direction) is enlarged and shown. In FIG. 2, the support plate 50 and the like are omitted for ease of understanding.
FIG. 3 is a view of the first optical shape layer 12 of the first embodiment as viewed from the back surface side (−Z side). For ease of understanding, the reflective layer 13, the second optical shape layer 14, the protective layer 15, and the like of the screen 10 are omitted.
As shown in FIG. 2, the screen 10 includes a base material layer 11, a first optical shape layer 12, a reflection layer 13, a second optical shape layer 14, and a protective layer 15 in this order from the image source side (+ Z side). ing.

The base material layer 11 is a sheet-like member having light transmission. The first optical shape layer 12 is integrally formed on the back surface side (back surface side, −Z side) of the base material layer 11. The base material layer 11 is a layer serving as a base material (base) for forming the first optical shape layer 12.
The base material layer 11 is, for example, a polyester resin such as PET (polyethylene terephthalate) having high light transmittance, an acrylic resin, a styrene resin, an acrylic styrene resin, a PC (polycarbonate) resin, an alicyclic polyolefin resin, and a TAC (triacetyl). Cellulose) It is formed of resin or the like.
Further, the thickness of the base material layer 11 can be changed according to the screen size of the screen 10 and the like, and the thickness in the present embodiment is about 100 μm.

The first optical shape layer 12 is a light-transmitting layer formed on the back surface side (−Z side) of the base material layer 11. A plurality of unit optical shapes (unit lenses) 121 are arranged and provided on the back surface (−Z side) surface of the first optical shape layer 12. As shown in FIG. 3, a plurality of unit optical shapes 121 are arranged concentrically around a point C located outside the screen (display area) of the screen 10. That is, the first optical shape layer 12 has a circular Fresnel lens shape on the back surface side. As shown in FIG. 3, this point C is located at the center in the left-right direction of the screen and at the lower side of the screen. Therefore, when the screen 10 is viewed from the front direction, the points C and A are located in the same linear shape.
The circular Fresnel lens shape of the first optical shape layer 12 is a circular Fresnel lens shape having a so-called offset structure centered on the point C (Fresnel center). Therefore, as shown in FIG. 3, when the first optical shape layer 12 is viewed from the back side in the normal direction of the screen surface, the unit optical shape (unit lens) 121 which is a partial shape (arc shape) of a perfect circle is formed. Observed as if they were arranged in multiples.

As shown in FIG. 2, the unit optical shape 121 has a substantially triangular cross-sectional shape in a cross section parallel to the direction orthogonal to the screen surface (Z direction) and parallel to the arrangement direction of the unit optical shape 121. ..
The unit optical shape 121 is convex on the back surface side, and has a first slope (lens surface) 121a on which image light is incident and a second slope (non-lens surface) 121b facing the first slope (lens surface) 121a.
In one unit optical shape 121, the second slope 121b is located below the first slope 121a with the apex t in between.
The angle formed by the first slope 121a with the surface parallel to the screen surface is θ1. The angle formed by the second slope 121b with the plane parallel to the screen plane is θ2. The angles θ1 and θ2 satisfy the relationship of θ2> θ1.
The first slope 121a and the second slope 121b of the unit optical shape 121 have fine uneven shapes on their surfaces. The fine uneven shape is formed by irregularly arranging the convex shape and the concave shape in the two-dimensional direction, and the convex shape and the concave shape have irregular sizes, shapes, heights, and the like.

The arrangement pitch of the unit optical shape 121 is P, and the height of the unit optical shape 121 (the dimension from the apex t in the thickness direction to the point v which is the valley bottom between the unit optical shapes 121) is h.
For ease of understanding, FIG. 2 shows an example in which the arrangement pitch P and the angles θ1 and θ2 of the unit optical shape 121 are constant in the arrangement direction of the unit optical shape 121. However, in the unit optical shape 121 of the present embodiment, the arrangement pitch P is actually constant, but the angle θ1 gradually increases as the angle θ1 moves away from the point C which becomes the Fresnel center in the arrangement direction of the unit optical shape 221. ..
The angles θ1, θ2, the arrangement pitch P, etc. are the projection angle of the image light from the image source LS (angle of the image light incident on the screen 10), the size of the pixels of the image source LS, and the screen of the screen 10. It may be appropriately set according to the size, the refractive index of each layer, and the like. For example, the arrangement pitch P may change along the arrangement direction of the unit optical shape 121, and the angles θ1 and θ2 may change.

The first optical shape layer 12 is formed of an ultraviolet curable resin such as urethane acrylate-based, polyester acrylate-based, epoxy acrylate-based, polyether acrylate-based, polythiol-based, and butadiene acrylate-based, which have high light transmittance. The first optical shape layer 12 is set to be lower than the refractive index of the dielectric film applied to the reflective layer 13 described later, and it is desirable that the refractive index is 1.60 or less. If the refractive index of the first optical shape layer 12 is larger than 1.60, the difference in the refractive index from the reflective layer 13 (dielectric film) becomes small, and the light between the first optical shape layer 12 and the reflective layer 13 It is not desirable because the reflection efficiency of the light is reduced.
The first optical shape layer of the present embodiment is formed of a urethane acrylate resin (refractive index 1.52) that is cured by ultraviolet rays.
The resin constituting the first optical shape layer 12 is not limited to the above-mentioned ultraviolet curable resin, and may be formed of, for example, another ionizing radiation curable resin such as an electron beam curable resin. Good.

FIG. 7 is a diagram illustrating the relationship between the 1/2 angle α, the incident angle φ of the image light, and the angle θ1 of the first slope 121a. FIG. 7 corresponds to the cross section of the screen 10 shown in FIG. 2, and in order to facilitate understanding, the configuration of the screen 10 is simplified, and the base material layer 11 and the protective layer 15 are omitted. Further, in FIG. 7, with respect to the angles α and φ, the upper side (+ Y side) of the screen vertical direction (Y direction) is shown as a plus and the lower side (−Y side) is shown as a minus with respect to the direction orthogonal to the screen surface. ..
Here, the angle of the peak brightness of the light (reflected light) projected from the image source LS, incident on the screen 10, incident on the reflection layer 13 formed on the first slope 121a, diffusely reflected, and emitted from the screen 10. The angles at which the brightness is halved in the vertical direction of the screen (the arrangement direction of the unit optical shapes 121 in FIG. 7) with respect to K are K1 and K2, and the angle at which the brightness is halved from the peak brightness angle K. When the amount of angle change up to K1 and K2 is + α1 (however, K + α1 = K1) and -α2 (K-α2 = K2), the absolute value of the amount of angle change from peak brightness to brightness halved. Let the average value be α (hereinafter, this is referred to as 1/2 angle α).

The angle θ1 of the first slope 121a is such that the image light L is most efficiently reflected by the observer O1 located in the front direction of the image source side (+ Z side) of the screen 10, that is, the peak brightness of the reflected light. The angle K is designed to be 0 ° based on the refractive index of each layer and the like. Further, the range from −α to + α is a range assuming that the observer O1 located in front of the screen observes the image well.
Here, at a certain point in the vertical direction of the screen (the arrangement direction of the unit optical shapes 121 in FIG. 7), the image light L is incident from below the screen 10 at an incident angle −φ, and the first optical shape layer 12 having a refractive index n is When the light is incident on the first slope 121a forming an angle θ1 with respect to the screen surface, reflected by the reflection layer 13, and is emitted from the screen 10 in a direction orthogonal to the screen surface (exit angle 0 °), the angle θ1 is set. , It is represented by the following (Equation 1).
θ1 = 1/2 × arcsin ((sin (φ)) / n) ・ ・ ・ (Equation 1)

When the image light L is projected from the image source LS onto the screen 10 and the image is displayed on the screen of the screen 10 which is a reflective screen, the light source of the image source LS that projects the image light L is reflected and the contrast of the image is lowered. There may be a problem of doing. The main cause of the reflection of this image source is that the image light reflected on the surface of the screen reaches the observer O1.
In order to prevent such reflection of the image source, the screen 10 is outside the angle range (−α to + α) on the surface of the screen 10, which is the range in which the observer O1 mainly observes the image well. It is preferable that the image light reflected on the surface of the screen advances. When a part Lr of the image light L incident at an incident angle −φ is reflected on the surface of the screen 10, the reflection angle is + φ. Therefore, it is preferable that α <φ in order to prevent reflection of the image source.

Therefore, from the above (Equation 1), in the vertical direction of the screen (arrangement direction of the unit optical shape 121), the 1/2 angle α and the angle θ1 of the first slope 121a are at least a part of the screen 10 (for example, , The center of the screen), it is preferable to satisfy the following (Equation 2).
α <arcsin (n × sin (2 × (θ1))) ・ ・ ・ (Equation 2)
Further, in order to prevent reflection of the image source, it is more preferable that the 1/2 angle α and the angle θ1 of the first slope 121a satisfy the above (Equation 2) in the entire area of the screen 10.
By adopting a form in which the angles θ1 and 1/2 angle α satisfy the above (Equation 2), the direction (direction of + φ) in which the light reflected on the surface of the screen 10 is mainly directed when incident on the screen 10 is set. The image light reflected by the reflective layer 13 is outside the angular range (−α to + α) that is emitted from the screen 10 and mainly travels. As a result, on the image source side (+ Z side), the reflection of the image source LS in the range (angle −α to + α) in which the observer O1 visually recognizes the image can be reduced, and a good image with high contrast can be displayed. it can.

Returning to FIG. 2 and the like, the reflection layer 13 is a layer having a function of reflecting light, and is formed on the unit optical shape 121 (on the first slope 121a and the second slope 121b).
The reflective layer 13 is a semi-transmissive reflective layer, a so-called half mirror, that reflects a part of the incident light and transmits the other.
As described above, the first slope 121a and the second slope 121b are formed with a fine uneven shape, and the reflection layer 13 is formed following the fine uneven shape. Further, the thickness of the reflective layer 13 is sufficiently thinner than the unevenness of the fine uneven shape. Therefore, the surface of the reflection layer 13 on the first optical shape layer 12 side (image source side) and the surface on the second optical shape layer 14 side (back surface side) are matte surfaces having a fine uneven shape.
The reflective layer 13 has a function of diffusing and reflecting a part of the incident light due to the fine uneven shape, and transmitting other non-reflected light without diffusing it.

The surface roughness of the surface of the reflective layer 13 on the image source side (that is, the surface roughness of the first slope 121a) is such that the arithmetic mean roughness Ra (JIS B 0601: 2001) is about 0.10 to 0.50 μm. It is preferable from the viewpoint of realizing a good viewing angle and displaying a good image. The surface roughness of the surface of the reflective layer 13 on the image source side (that is, the surface roughness of the unit optical shape 121) may be appropriately selected according to the desired optical performance and the like.

Further, of the first slope 121a, a region that is not a rough surface, that is, a region in which a fine uneven shape is not formed and is formed on the first slope 121a on the image source side (first). The surface on the optical shape layer 12 side) is mirror-finished, and the mirror-finished region where the incident image light is mirror-reflected is per unit area of the reflection layer 13 formed on the first slope 121a (per unit area of the first slope 121a). ) 5% or less is necessary for sufficiently diffusing the image light and obtaining a good viewing angle, and ideally 0%.
If the mirror surface region exceeds 5%, bright lines are generated or the viewing angle is lowered due to the components of the image light that is reflected without being diffused and reaches the image source side, which is not preferable.

The reflectance and transmittance of the reflective layer 13 can be appropriately set according to the desired optical performance, but the image light is reflected well and light other than the image light (for example, light from the outside such as sunlight). It is desirable that the transmittance is about 60 to 85% and the reflectance is about 5 to 20% from the viewpoint of satisfactorily transmitting the light.

The reflective layer 13 is formed of a single-layer dielectric film capable of achieving higher transparency and reflectance than a metal vapor deposition film or the like.
This dielectric film is formed of a material having a higher refractive index than the first optical shape layer 12 described above and the second optical shape layer 14 described later. For example, ZnS (zinc sulfide) and titanium oxide (TIO ₂ ) are formed. ), Niobium pentoxide (Nb ₂ O ₅ ) and the like, and the refractive index is about 2.0 to 2.6.
The difference in refractive index between the dielectric film (reflection layer 13) and the first optical shape layer 12 (second optical shape layer 14) is preferably 0.5 or more.

The film thickness of this single-layer dielectric film is preferably 30 nm or more and 100 nm or less, and if it deviates from this film thickness range, the reflective layer becomes tinted, and the image light or the light of the outside world This is not desirable as it reduces sharpness.
The reflective layer 13 has a reflectance of about 5 to 20% and a transmittance of about 60 to 85% with respect to light having a wavelength range of 400 to 800 nm.

The reflective layer 13 formed of the dielectric film has higher transparency than the reflective layer formed of a metal vapor deposition film such as aluminum, has a small light absorption loss, and has a high reflectance. Can be realized. Here, since the reflective layer 13 formed of the single-layer dielectric film has a higher refractive index than the first optical shape layer 12, the image light incident on the interface with the first optical shape layer 12 is efficiently reflected. Can be made to. Further, the reflective layer 13 made of the dielectric film has a second optical shape layer 14 (described later) formed on the back surface side, and the second optical shape layer 14 has a refractive index equivalent to that of the first optical shape layer 12. Therefore, it is possible to reflect the incident image light even at the interface with the second optical shape layer 14.
The reflective layer 13 is formed to have a predetermined thickness by depositing or sputtering the dielectric film as described above on the unit optical shape 121 (on the first slope 121a and the second slope 121b). Ru.
The reflective layer 13 of the present embodiment is a dielectric film formed of ZnS (refractive index 2.36).

The second optical shape layer 14 is a light-transmitting layer provided on the back surface side (−Z side) of the first optical shape layer 12. The second optical shape layer 14 is provided to flatten the back surface (−Z side) of the first optical shape layer 12, and is formed so as to fill the valley between the unit optical shapes 121. There is. Therefore, the surface of the second optical shape layer 14 on the image source side (+ Z side) is formed by arranging a plurality of substantially inverted shapes of the unit optical shape 121 of the first optical shape layer 12.
By providing such a second optical shape layer 14, the reflective layer 13 can be protected, the protective layer 15 and the like can be easily laminated on the back surface of the screen 10, and the protective layer 15 and the like can be easily bonded to the support plate 50 and the like. It becomes.

It is desirable that the refractive index of the second optical shape layer 14 is equal to or substantially equal to the refractive index of the first optical shape layer 22 (the difference in refractive index is small enough to be regarded as equal). Further, the second optical shape layer 14 is preferably formed by using the same ultraviolet curable resin as the first optical shape layer 12 described above, but may be formed by a different material.
The second optical shape layer 14 of the present embodiment is formed of the same material (urethane acrylate resin) as the first optical shape layer 12 described above, and its refractive index is the refractive index (1.52) of the first optical shape layer 12. be equivalent to.

The protective layer 15 is a light-transmitting layer formed on the back surface side (−Z side) of the second optical shape layer 14, and has a function of protecting the back surface side (−Z side) of the screen 10. ing.
As the protective layer 15, a sheet-like member made of resin having high light transmission is used. As the protective layer 15, for example, a sheet-like member formed by using the same material as the above-mentioned base material layer 11 may be used.
The protective layer 15 may not be provided when the support plate 50 or the like is joined to the back surface side as in the present embodiment.
As described above, the screen 10 of the present embodiment does not have a light diffusing layer containing a diffusing material such as particles having a diffusing effect, and only the fine uneven shape of the reflective layer 13 has a diffusing effect. is there.

The screen 10 is formed by, for example, the following manufacturing method.
A UV base layer 11 is prepared, and one surface thereof is laminated with an ultraviolet curable resin filled in a molding mold that forms a unit optical shape 121, and is irradiated with ultraviolet rays to cure the ultraviolet curable resin. The first optical shape layer 12 is formed by a molding method. At this time, fine uneven shapes are formed on the surfaces forming the first slope 121a and the second slope 121b of the molding die that shape the unit optical shape 121. This fine uneven shape is formed by repeating plating under different conditions twice or more, etching treatment, blasting treatment, etc. on the surfaces on which the first slope 121a and the second slope 121b of the molding die are formed. it can.
After the first optical shape layer 12 is formed on one surface of the base material layer 11, the reflective layer 13 is formed by depositing a dielectric film on the first slope 121a and the second slope 121b.

After that, the ultraviolet curable resin is applied from above the reflective layer 13 so as to fill the valley between the unit optical shapes 121 so as to be flat, the protective layer 15 is laminated, and the ultraviolet curable type is irradiated with ultraviolet rays. The resin is cured to integrally form the second optical shape layer 14 and the protective layer 15. After that, the screen 10 is completed by cutting it to a predetermined size or the like.
The base material layer 11 and the protective layer 15 may have a single-wafer shape or a web-like shape. Further, as described above, the screen 10 may be in a form in which the protective layer 15 is not provided.

As a method of forming a rough surface on the first slope 121a and the second slope 121b, for example, diffusion particles or the like are applied on the first slope 121a and the second slope 121b to form a reflective layer 13 on the first slope 121a and the second slope 121b. (1) A method of blasting the first slope 121a and the second slope 121b after forming the optical shape layer 12 is conventionally known.
However, when fine and irregular uneven shapes are formed on the first slope 121a and the second slope 121b to make a rough surface by such a manufacturing method, the diffusion characteristics, quality, and the like of the individual screens 10 vary. Large and stable production cannot be performed. On the other hand, as described above, a large number of first optical shape layers 12 and screens 10 are formed by shaping the fine uneven shapes of the first slope 121a and the second slope 121b of the unit optical shape 121 by a molding die. Even in the case of manufacturing, there is an advantage that there is little variation in quality and stable manufacturing is possible.

FIG. 4 is a diagram showing the state of image light and external light on the screen 10 of the first embodiment. FIG. 4 shows an enlarged part of a cross section of the unit optical shape 121 in a cross section parallel to the arrangement direction (Y direction) and the thickness direction (Z direction) of the screen. Further, in FIG. 4, in order to facilitate understanding, it is shown that there is no difference in refractive index at the interface of each layer in the screen 10.
Of the image light L1 projected from the image source LS located below the screen 10 and incident on the screen 10, a part of the image light L2 is incident on the first slope 121a of the unit optical shape 121, and the reflection layer 13 Is diffusely reflected at the interface between the light and each optical shape layer (12, 14), and is emitted to the observer O1 side.

Of the video light incident on the first slope 121a, the other video light L3 that has not been reflected passes through the reflection layer 13 and is emitted from the back surface side (−Z side) of the screen 10. At this time, the image light L3 is emitted above the screen 10 and does not reach the observer O2 located in the front direction on the back side of the screen 10.
Further, of the image light L1 projected from the image source LS, a part of the image light L4 is reflected on the surface of the screen 10 and heads upward on the screen 10. At this time, since the reflection angle of the image light L4 is larger than the 1/2 angle α or more as described above, it does not interfere with the visual recognition of the image of the observer O1.
In the present embodiment, the image source LS is located below the screen 10, the image light L1 is projected from below the screen 10, and the angle θ2 (see FIG. 2) of the second slope 121b is the screen 10. Since it is larger than the incident angle of the image light at each point in the vertical direction of the screen, the image light does not directly enter the second slope 121b, and the second slope 121b has almost no effect on the reflection of the image light.

Next, light from the outside world such as sunlight (hereinafter referred to as external light) other than the image light incident on the screen 10 from the back surface side (−Z side) or the image source side (+ Z side) will be described.
As shown in FIG. 4, of the external light G1 and G5 incident on the screen 10, some of the external light G2 and G6 are reflected by the surface of the screen 10 and head toward the lower side of the screen. Further, some external light G3 and G7 are reflected at the interface between the reflective layer 13 and each optical shape layer (12, 14). For example, the external light G3 is on the image source side (+ Z side) of the screen 10. It is totally reflected on the surface and heads downward inside the screen 10, and the external light G7 is emitted to the upper side outside the screen on the back side (−Z side). Further, the other external light G4 and G8 that are not reflected by the reflection layer 13 pass through the reflection layer 13 and are emitted to the back surface side and the image source side, respectively. At this time, since the external lights G2, G3, and G8 emitted to the image source side do not reach the observer O, the decrease in contrast of the image can be suppressed.

Further, a part of the external light incident on the screen 10 is totally reflected on the surface of the screen 10 on the image source side and the back surface side, and is attenuated toward the lower side inside the screen.
Further, the other external lights G9 and G10 pass through the reflective layer 13 and are emitted to the back side and the image source side, respectively. Since the screen 10 does not contain a diffusing material or the like containing diffusing particles, the external light G9 and G10 transmitted through the screen 10 are not diffused. Therefore, when the scenery on the other side of the screen 10 is observed through the screen 10, the scenery on the other side of the screen 10 can be observed with high transparency without blurring or bleeding white.

In the conventional semi-transmissive reflective screen provided with a diffusing layer containing diffusing particles, the image light is diffused twice before and after the reflection by the reflective layer, so that a good viewing angle can be obtained while the resolution of the image is obtained. There is a problem that In addition, since external light is also diffused by the diffused particles, the scenery on the other side of the screen is observed to be blurred or bleeding white, and the transparency is lowered.

However, since the screen 10 of the present embodiment has no diffusing action except that the surface of the reflective layer 13 on the image source side has a fine uneven shape, the image light is diffused only at the time of reflection. Further, in the screen 10 of the present embodiment, only the light reflected by the reflective layer 13 is diffused, and the transmitted light is not diffused. Therefore, the screen 10 of the present embodiment can display an image having a good viewing angle and resolution, and the scenery on the other side of the screen 10 is not blurred or blurred, and is well visible to the observer O1. And high transparency can be achieved. Further, in the screen 10 of the present embodiment, the observer O1 can partially see the scenery on the other side (back side) of the screen 10 even when the image light is projected on the screen 10. Further, in the screen 10 of the present embodiment, the observer O2 located on the back side has high transparency in the scenery on the image source side (+ Z side) through the screen 10 regardless of the presence or absence of projection of image light. Can be visually recognized well.

Here, various optical performances related to the screen 10 of the present embodiment will be described.
The screen 10 has a diffuse reflectance of 5% or more and 35% or less with respect to incident light from a direction orthogonal to the screen surface (incident angle to the screen surface is 0 °).
The diffuse reflectance is the ratio of the diffuse reflected light in the reflected light incident on the screen 10 from the image source side at an incident angle of 0 ° and reflected by the reflecting layer 13, and is obtained by measurement with a spectrophotometer having an integrating sphere or the like. Be done. When the diffuse reflectance is less than 5%, the viewing angle of the image displayed on the screen 10 is too narrow, which hinders good visibility of the image. Further, when the diffuse reflectance becomes larger than 35%, the brightness of the image is lowered. Therefore, the diffuse reflectance of the screen 10 is preferably in the above range.

Further, the screen 10 has a total light transmittance of 70% or more and 85% or less of the incident light from a direction orthogonal to the screen surface (incident angle to the screen surface is 0 °).
The total light transmittance is the ratio of the total transmitted light to the light incident on the screen 10 at an incident angle of 0 °, and can be obtained by measurement with a haze meter or the like. When the total light transmittance is less than 70%, the transparency of the screen is lowered, which is not preferable. Further, if the total light transmittance is larger than 85%, the amount of transmitted light becomes too large and the displayed image becomes dark, which is not preferable. Therefore, the total light transmittance of the screen 10 is preferably in the above range.
In the screen of the present embodiment, the total light transmittance when incident from the image source side is equal to the total light transmittance when incident from the back surface side.

Further, the screen 10 preferably has a haze value of 5.0% or less.
This haze value is the ratio of the diffusion transmittance to the total light transmittance, and can be obtained by measurement with a haze meter or the like. If it is larger than 5.0%, the transparency of the screen 10 is lowered, the scenery on the other side of the screen is observed whitish, and the contrast of the image is lowered, which is not preferable. Therefore, the haze value of the screen 10 is preferably in the above range.

Further, the peak gain of the screen 10 is preferably 0.2 or more and 3.5 or less.
The gain is a numerical value indicating the reflection characteristics of the screen 10, and is the same when the brightness of the reflected light when irradiating a complete diffuser plate (pure white plate obtained by firing magnesium oxide, etc.) with a light source (white light) is 1. The brightness value measured from each angle in the left-right direction (horizontal direction) of the screen at the point A at the center of the screen on the surface of the screen 10 on the image source side, which is illuminated by the light source from the front direction of the image source side at an incident angle of 32 °. Obtained by ratio. The highest value of this gain is called a peak gain, and in this embodiment, it is a value measured from the front direction on the image source side. If the peak gain of the screen 10 is less than 0.2, the brightness of the image is lowered, which is not preferable. Further, when the peak gain of the screen 10 is larger than 3.5, the viewing angle becomes too narrow, which is not preferable. Therefore, the peak gain of the screen 10 is preferably in the above range.

Further, the 1/2 angle α of the screen 10 preferably satisfies 5 ° ≦ α ≦ 30 °.
As described above, the 1/2 angle α is in the vertical direction of the screen with respect to the angle K which is the peak brightness of the light emitted from the screen 10 after being incident on the screen 10 and diffusely reflected by the reflection layer 13 (unit optics in FIG. 7). In the arrangement direction of the shape 121), the angle at which the brightness is halved is K1 and K2, and the amount of angle change from the peak brightness angle K to the angle K1 and K2 at which the brightness is halved is + α1 (however, K + α1). When = K1) and −α2 (K−α2 = K2), it is the average value of the absolute values of the amount of change in the angle from the peak brightness to the brightness being halved.
In the screen 10 of the present embodiment, since the uneven shape of the reflective layer 13 is irregular, the 1/2 angle α in the horizontal direction of the screen is equal to or substantially equal to the 1/2 angle α in the vertical direction of the screen. Therefore, it is preferable that the 1/2 angle α in the left-right direction of the screen also satisfies 5 ° ≦ α ≦ 30 °.

When α <5 °, the viewing angle for displaying a good image for the observer O1 becomes too narrow, and the image becomes difficult to see, which is not preferable. Further, when α <5 °, the specular reflection component increases in the reflected light, and the reflection of the image source or the like occurs, which is not preferable.
When α> 30 °, the viewing angle for displaying a good image to the observer O1 becomes wide, but the brightness of the image decreases, the image becomes blurred, or the external light is displayed on the screen 10. It is not preferable because the contrast of the image is lowered due to the reflection.
Therefore, the above range is preferable for the 1/2 angle α of the screen 10 in the horizontal direction of the screen and the vertical direction of the screen.

Here, the screens of Measurement Examples 1 to 7 having different total light transmittance, haze value, diffuse reflectance, peak gain, and 1/2 angle α are prepared, and the illuminance at the point A at the center of the screen is about 700 lpx. Under the bright room environment, observation was performed from a position 2 m from point A to the image source side (+ Z side), and the appearance of the image and the transparency of the screen were evaluated, and the results are summarized in Table 1.
The screen of each measurement example has the same form except that the total light transmittance, the haze value, the diffuse reflectance, the peak gain, and the 1/2 angle α are different.
The total light transmittance, haze value, diffuse reflectance, and peak gain were measured at a point A at the center of the screen of each measurement example.
The haze meter used for the measurement was HM-150 manufactured by Murakami Color Technology Laboratory Co., Ltd., and the spectrophotometer was an ultraviolet-visible near-infrared spectrophotometer (V-670) manufactured by JASCO Corporation. .. A three-dimensional variable angle spectrophotometric colorimetric system (GCMS-11) manufactured by Murakami Color Technology Research Institute Co., Ltd. was used for the peak gain measurement.
The "judgment" in Table 1 is an evaluation by the observer's visual inspection, and is evaluated as "○" when a bright and good image is observed and the viewing angle is sufficient, and "x" in other cases. ..

As described above, the screens of Measurement Examples 2 to 6 in which the total light transmittance, the haze value, the diffuse reflectance, the peak gain, and the 1/2 angle α satisfy the preferable ranges are bright and good images are observed. The viewing angle was also sufficient.
However, in the screen of Measurement Example 1 in which the total light transmittance and the haze value do not satisfy the preferable ranges, the transparency of the screen is low, and the scenery on the other side of the screen is observed whitish, so that the image becomes whitish and the contrast becomes high. It was not preferable because it decreased.
Further, in the screen of Measurement Example 7 in which the total light transmittance and the diffuse reflectance do not satisfy the preferable ranges, although the screen transparency is obtained, the brightness of the image is lowered and the image becomes dark, which is preferable. There wasn't.

From the above, since the screen 10 of the present embodiment satisfies the preferable ranges with respect to the total light transmittance, the haze value, the diffuse reflectance, the peak gain, and the 1/2 angle α, it is bright while maintaining the transparency. , A good image with a sufficient viewing angle can be displayed.
Further, in the screen 10 of the present embodiment, since the 1/2 angle α and the angle θ1 of the image light (reflected light) diffusely reflected by the reflection layer 13 satisfy the above-mentioned (Equation 2), the image of the screen 10 is satisfied. The image light reflected on the surface on the source side goes outward from the 1/2 angle α, and there is no reflection of the image source LS, so that a good image can be displayed.

Further, according to the present embodiment, in the first optical shape layer 12, the point C serving as the Fresnel center is located outside the display area and on the image source LS side, and has a so-called offset structure circular Fresnel lens shape. Therefore, even if the image light L has a large incident angle projected from the image source LS, which is a short focus type projector, the image in the left-right direction of the screen does not become dark and the surface uniformity of brightness does not occur. It is possible to display a high quality image.

(Second Embodiment)
FIG. 5 is a diagram illustrating the screen 20 of the second embodiment. FIG. 5A is a view of the first optical shape layer 22 of the screen 20 as viewed from the back surface side (−Z side), and in order to facilitate understanding, the reflective layer 13 and the second optical shape layer 14 The protective layer 15 and the like are omitted. FIG. 5B is an enlarged view of a part of the cross section of the screen 20 of the second embodiment, which corresponds to the cross section of the screen 10 of the first embodiment shown in FIG.
The screen 20 shown in the second embodiment has the same embodiment as the above-described first embodiment except that the shape of the unit optical shape 221 of the first optical shape layer 22 is different. Therefore, the same reference numerals or the same reference numerals are given to the parts that perform the same functions as those of the first embodiment described above, and duplicate description will be omitted as appropriate.
The screen 20 of the second embodiment can be used in place of the screen 10 in the image display device 1 of the first embodiment described above.

The screen 20 includes a base material layer 11, a first optical shape layer 22, a reflection layer 13, a second optical shape layer 14, and a protective layer 15.
The first optical shape layer 22 is provided with a plurality of unit optical shapes 221 arranged on a surface on the back surface side (−Z side) thereof.
A plurality of unit optical shapes 221 extend in the screen left-right direction (X direction) of the screen 10 and are arranged along the screen vertical direction (Y direction). The unit optical shape 221 has a triangular cross-sectional shape in a cross section parallel to the thickness direction (Z direction) of the screen 10 and parallel to the arrangement direction (Y direction) of the unit optical shape 121, which is a so-called prism shape. ..

The unit optical shape 221 has a first slope 221a on which image light is directly incident, and a second slope 221b facing the first slope 221a. In one unit optical shape 221 the second slope 221b is located on the lower side (−Y side) than the first slope 221a with the apex t interposed therebetween.
In this embodiment, as shown in FIG. 5, an example in which the angles θ1 and θ2, the arrangement pitch P, and the like are constant is shown. However, not limited to this, these angles and dimensions include the projection angle of the image light from the image source LS (angle of the image light incident on the screen 10), the size of the pixels of the image source LS, and the screen. It may be appropriately set according to the screen size of 10 and the refractive index of each layer. For example, these angles and dimensions may change gradually or stepwise along the arrangement direction of the unit optical shape 121.

In the unit optical shape 221 as shown in FIG. 5B, the angle formed by the first slope 221a with the surface parallel to the screen surface is θ1, and the angle formed by the second slope 221b with the surface parallel to the screen surface. Is θ2. At this time, the angles θ1 and θ2 satisfy the relationship θ2> θ1. This angle θ1 satisfies the above-mentioned (Equation 2) with respect to the 1/2 angle α.

Similar to the screen 10 of the first embodiment described above, the screen 20 of the present embodiment has a total light reflectance, a diffuse reflectance, a haze value, a peak gain, and a 1/2 angle α satisfying a preferable range.
Therefore, according to the present embodiment, it is possible to provide the semitransparent screen 20 and the display device 1 which are highly transparent and can display a good image, as in the first embodiment described above.
Further, according to the present embodiment, the unit optical shapes 221 are arranged in the vertical direction (Y direction) of the screen with the horizontal direction (X direction) of the screen as the longitudinal direction, so that the first optical shape layer 22 and the screen 20 are arranged. Is easy to manufacture, and the large screen screen 20 can be easily manufactured. Further, for example, by using the web-shaped base material layer 11 and the protective layer 15, the screen 20 in the state before cutting can be continuously and easily manufactured, the production efficiency of the screen 10 is improved, and the production cost is reduced. It can be reduced.

(Transformed form)
Not limited to each of the embodiments described above, various modifications and changes are possible, and these are also within the scope of the present invention.
(1) In each embodiment, a hard coat layer may be provided on the image source side (+ Z side) of the screens 10 and 20 for the purpose of preventing scratches. For the hard coat layer, for example, an ultraviolet curable resin having a hard coat function (for example, urethane acrylate or the like) is applied to the surface of the screens 10 and 20 on the image source side (the surface of the base material layer 11 on the image source side). It is formed by forming the film.
Further, not limited to the hard coat layer, a layer having appropriately necessary functions such as an antireflection function, an ultraviolet absorption function, an antifouling function, an antistatic function, etc., depending on the usage environment and purpose of use of the screens 10 and 20. May be provided by selecting one or more. Further, a touch panel layer or the like may be provided on the image source side (+ Z side) of the base material layer 11.
For example, when the antireflection layer is provided on the surface of the screens 10 and 20 on the image source side, a part of the light reflected by the reflection layer 13 is reflected on the surface on the image source side and emitted from the back side. , It is possible to prevent the observer O2 on the back side from seeing a part of the image.

(2) In each embodiment, the image source LS has been described with reference to an example in which the image source LS is located at the center of the screens 10 and 20 in the left-right direction of the screen and below the outside of the screen, but the present invention is not limited to this. , 20 may be arranged diagonally below the screens 10 and 20, and the image light may be projected from the oblique light in the left-right direction of the screen with respect to the screens 10 and 20.
FIG. 6 is a diagram showing a modified form of the image display device 1A. FIG. 6 shows an example using the screen 20 of the second embodiment as an example.
As shown in FIG. 6, for example, when the image source LS is arranged below the left side (−X side) of the screen 10 in the left-right direction of the screen, the unit optical shape 121 has the arrangement direction and the longitudinal direction of the image source LS. It is tilted with respect to the vertical direction (Y direction) and the horizontal direction (X direction) of the screen according to the position. With such a form, the position of the image source LS and the like can be freely set.
Even when the first optical shape layer 12 has a circular Fresnel lens shape as in the screen 10 shown in the first embodiment, the arrangement direction of the unit optical shape 221 is tilted according to the position of the image source LS. Therefore, such a modified form is applicable.

(3) In each embodiment, the unit optical shapes 121 and 221 show an example in which the first slopes 121a and 221a and the second slopes 121b and 221b are formed by a flat surface, but the present invention is not limited to this, and for example, a curved surface is used. It may be in the form of a combination with a flat surface or in a folded surface shape.
Further, in each embodiment, the unit optical shapes 121 and 221 may be polygonal shapes formed by a plurality of three or more surfaces.
Further, in each embodiment, the example in which the reflective layer 13 is formed on the first slopes 121a and 221a and the second slopes 121b and 221b is shown, but the present invention is not limited to this, and for example, at least the first slopes 121a and 221a are shown. It may be a form formed in a part.
Further, in each embodiment, the first slopes 121a, 221a and the second slopes 121b, 221b are rough surfaces in which fine uneven shapes are formed, but the present invention is not limited to this, and the first slope 121a, Only 221a may have a rough surface.

(4) In each embodiment, the screens 10 and 20 include the base material layer 11 and the protective layer when the first optical shape layer 12 and the second optical shape layer 14 have sufficient thickness, rigidity, and the like. The form may not include 15, or may not include either one.
Further, in each embodiment, the screens 10 and 20 may have at least one of the base material layer 11 and the protective layer 15 as a plate-shaped member having light transmission such as a glass plate. At this time, the first optical shape layer 12 or the like may be bonded to the glass plate or the like via the adhesive layer or the like.

(5) In each embodiment, the image source LS may project, for example, image light having a polarization component of a P wave.
At this time, the position and angle of the image source LS are set so that the image light is projected onto the screens 10 and 20 at an incident angle φ. This incident angle φ is (θb-10) ° or more when the incident angle (Brewster's angle) at which the reflectance of the image light (P wave) projected on the screens 10 and 20 is zero is θb (°). It is set in the range of 85 ° or less. For example, when the incident angle θb at which the reflectance of the video light projected on the screens 10 and 20 becomes zero is 60 °, the incident angle φ of the video light is set in the range of 50 to 85 °.
In this way, by using the image source LS that projects the image light having the polarization component of the P wave, the specular reflection on the surface of the screens 10 and 20 is suppressed even when the angle of incidence φ on the screens 10 and 20 is large. This makes it possible to increase the degree of freedom in designing the projection system, such as the installation position of the image source LS. Further, by using such an image source LS, it is possible to reduce the reflection of the image light on the screen surface when it is incident on the screens 10 and 20, and it is possible to improve the brightness and sharpness of the image.
The angle θb (Brewster's angle) differs depending on the material of the surfaces of the screens 10 and 20 on which the image light is projected.
Further, in such a form, a sheet-shaped member made of TAC is suitable as the base material layer 11 and the protective layer 15.

(6) In each embodiment, the image display device 1 is arranged in a show window of a store or the like, but the present invention is not limited to this, and is not limited to this, for example, for indoor partitions, image display at exhibitions, and the like. Can also be applied. Further, the image display device 1 may be applied to an automobile head-up display (HUD: HEAD-Up Display) by attaching screens 10 and 20 to the windshield, or may be applied to a vehicle other than an automobile. Good.

(7) In each embodiment, the screens 10 and 20 may be sandwiched between two transparent substrates, for example, a glass substrate to form a laminated glass-like optical member. In this case, a transparent bonding material (for example, PVB or the like) is provided between the screens 10 and 20 and each transparent base material, and the screen and each transparent base material are bonded to each other. Such a laminated glass-like optical member in which the screens 10 and 20 are sandwiched by a transparent base material (glass substrate) can be applied to, for example, a window of a vehicle such as an automobile, and can be used as, for example, a HUD. ..
Further, the base material layer 11 and the protective layer 15 may be replaced with transparent base materials (glass substrates) to form laminated glass-like optical members. As a result, the layer structure of the laminated glass-like optical member can be further simplified, the manufacturing cost of the optical member can be reduced, and the manufacturing efficiency can be improved.

(8) In each embodiment, the image source side is from the image source side surface of the screens 10 and 20 in the thickness direction (Z direction) (the image source side surface of the base material layer 11) to the back surface side of the reflection layer 13. When the area is from the image source side surface of the reflective layer 13 to the back surface side of the screens 10 and 20 (the back surface of the protective layer 15) as the back surface area, the light is incident from the back surface side of the screen surface of the screens 10 and 20. The absorption rate of the light in the back region to the light incident at an angle of 0 degrees is larger than the absorption rate of the light in the image source side region to the light incident at an incident angle of 0 degrees from the image source side of the screen surface of the screens 10 and 20. It may be made larger.
Specifically, a light-transmitting layer having light transmittance provided on the back side of the reflective layer 13, that is, at least one layer of the second optical shape layer 14 and the protective layer 15, a dye such as gray or black is used. A light-transmitting colored layer (light-transmitting layer) containing a coloring material such as a pigment, or containing the above-mentioned coloring material between the second optical shape layer 14 and the protective layer 15 or on the back side of the protective layer 15. ) Is separately provided, the light absorption rate in the back side region of the screens 10 and 20 described above can be made larger than the light absorption rate in the image source side region.
In this way, by making the light absorption rate of the back side region larger than the light absorption rate of the image source side region, when the other side (image source side) of the screens 10 and 20 is viewed from the back side, or While maintaining high transparency of the screens 10 and 20 when the other side (rear side) of the screens 10 and 20 is viewed from the image source side, unnecessary illumination light incident from the back side or external light such as sunlight Can be absorbed and the contrast of the image can be improved. Further, since the light transmitting layer containing the coloring material provided on the back side of the reflective layer 13 does not absorb the image light for displaying the image to the observer O1, the utilization efficiency of the image light required for displaying the image is high. Can be maintained high and a bright and clear image can be displayed.

(9) In each embodiment, the screens 10 and 20 have been described with the example in which the second optical shape layer 14 and the protective layer 15 are provided on the back surface side of the reflective layer 13, but the present invention is not limited to these. Layer may be omitted. In this case, the image light incident on the screen is reflected only at the interface between the reflection layer 13 and the first optical shape layer 12.

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

1 Image display device 10, 20 Screen 11 Base material layer 12 1st optical shape layer 121 Unit optical shape 121a 1st slope 121b 2nd slope 13 Reflective layer 14 2nd optical shape layer 15 Protective layer LS Video source

Claims (13)

A reflective screen that reflects the image light projected from the image source and displays the image.
An optical shape layer in which a plurality of unit optical shapes having light transmission and having a first surface on which image light is incident and a second surface facing the first surface and a second surface facing the first surface are arranged on the back surface side.
A reflective layer formed on at least a part of the first surface of the unit optical shape,
With
The unit optical shape has a fine and irregular uneven shape on its surface.
The surface of the reflective layer on the unit optical shape side has an uneven shape corresponding to the uneven shape.
The reflective layer has a function of reflecting a part of the incident light and transmitting the other, and is formed of a single-layer dielectric film.
Reflective screen featuring. In the reflective screen according to claim 1,
The dielectric film has a film thickness of 30 nm or more and 100 nm or less.
Reflective screen featuring. In the reflective screen according to claim 1 or 2.
The total light transmittance of the light incident on the reflection screen at an incident angle of 0 ° shall be 70% or more and 85% or less.
Reflective screen featuring. In the reflective screen according to any one of claims 1 to 3.
The diffuse reflectance of light incident on the reflection screen from the image source side at an incident angle of 0 ° shall be 5% or more and 35% or less.
Reflective screen featuring. In the reflective screen according to any one of claims 1 to 4.
The peak gain of the reflective screen is 0.2 or more and 3.5 or less.
Reflective screen featuring. In the reflective screen according to any one of claims 1 to 5.
The haze value of the reflective screen is 5.0% or less.
Reflective screen featuring. In the reflective screen according to any one of claims 1 to 6.
The dielectric film forming the reflective layer contains at least one of zinc sulfide (ZnS), titanium oxide (TiO ₂ ), and niobium pentoxide (Nb ₂ O ₅ ).
Reflective screen featuring. In the reflective screen according to any one of claims 1 to 7.
When the amount of angle change from the emission angle which is the peak brightness of the reflected light of the reflection screen to the emission angle where the brightness is halved is + α1 and −α2, and the average value of the absolute values is α, 5 ° ≦ α ≤ 30 °,
Reflective screen featuring. In the reflective screen according to any one of claims 1 to 8.
Not having a diffusion layer containing diffuse particles,
Reflective screen featuring. In the reflective screen according to any one of claims 1 to 9.
A second optical shape layer having light transmittance and laminated so as to fill the valley between the unit optical shapes is provided on the surface of the optical shape layer on the side where the unit optical shape is formed. ,
Reflective screen featuring. In the reflective screen according to any one of claims 1 to 10.
At least one light transmitting layer having light transmission is provided on the back surface side of the reflective layer.
In the thickness direction of the reflective screen, the image source side region is from the image source side surface of the reflective screen to the back surface side of the reflective layer, and from the image source side surface of the reflective layer to the back surface side surface of the reflective screen. When the area up to is the back side area
The absorption rate of the light in the back side region with respect to the light incident from the back side of the screen surface of the reflection screen at an incident angle of 0 degrees is the image of the light incident from the image source side of the screen surface of the reflection screen at an incident angle of 0 degrees. Greater than the light absorption rate in the source region,
Reflective screen featuring. The reflective screen according to any one of claims 1 to 11.
The first transparent base material arranged on the image source side of the reflective screen and
A second transparent base material arranged on the back side of the reflective screen,
An optical member comprising. The reflective screen according to any one of claims 1 to 11.
An image source that projects image light onto the reflective screen,
A video display device comprising.

Images