JP2014066820A - Transmission type screen and rear projection type display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transmission type screen that is able to remarkably reduce display failure such as ghost and able to display a satisfactory image, and to provide a rear projection type display device equipped with this.SOLUTION: In a transmission type screen 10, a screen surface has a curved shape, and an incident surface 10a, on which image light is made incident forms an incident surface 10a substantially flat, and has an incident side function layer 21 having an anti-reflection function layer. The incident side function layer 21 is formed from a vapor deposition film or sputter film of an inorganic compound. A rear projection type display device 1 comprises: this transmission type screen 10; a light source part 70 that projects image light; and a mirror part 80 located on the rear side of the transmission type screen 10 and configured to reflect image light from the light source part 70, thereby projecting it to the incident surface 10a of the transmission type screen 10.

Description

  The present invention relates to a transmissive screen and a rear projection display device including the transmissive screen.

2. Description of the Related Art Conventionally, in a rear projection type display device that projects and displays video light from the back side of the screen, a transmissive screen for transmitting and displaying the projected video light is widely used. Such transmissive screens have been proposed having various configurations in accordance with desired optical characteristics (see, for example, Patent Documents 1 and 2).
In recent years, a rear projection display device having a transmissive screen has a high design property, such as a sense of unity between the outer shape of the rear projection display device and the surface shape of the transmissive screen, depending on the application. May be required. In such a case, it is necessary to harmonize with the entire system in terms of design, and naturally, good image quality as a display device is also required.

JP-A-9-160132 JP 2008-281910 A

  In a rear projection type display device, image light from an image source may be reflected by a reflecting mirror or the like and projected onto a transmissive screen. By projecting image light using a reflecting mirror or the like, the depth space of the rear projection display device (the space on the rear side of the transmission screen) can be reduced, and space saving of the rear projection display device can be achieved. Such a technique is widely used.

When the light from the image source is projected onto the transmissive screen using the reflecting mirror as described above, the image light is reflected by the surface of the light incident surface of the transmissive screen, and the image light is reflected again by the reflecting mirror. May be incident on a transmissive screen. In particular, such a phenomenon is likely to occur when the light incident surface of the transmissive screen is smooth. Such image light is visually recognized as a ghost (double image) and hinders clear image display.
The above-mentioned Patent Documents 1 and 2 do not disclose any such ghost reduction.

  An object of the present invention is to provide a transmissive screen capable of significantly reducing display defects such as ghosts and the like and capable of displaying a good image, and a rear projection display device including the transmissive screen.

The present invention solves the above problems by the following means. In addition, in order to make an understanding easy, although the code | symbol corresponding to embodiment of this invention is attached | subjected and demonstrated, it is not limited to this.
The invention of claim 1 is a transmissive screen that displays video by transmitting image light projected from one surface side to the other surface side, and has a curved shape such that the screen surface forms a curved surface. The light incident surface (10a) on which the image light is incident has a substantially smooth surface, includes the light incident side functional layer (21) that forms the light incident surface and has an antireflection function, and the light incident side function. The layer is a transmission screen (10) characterized in that the layer is formed of a vapor-deposited film or a sputtered film of an inorganic compound.
According to a second aspect of the present invention, in the transmissive screen according to the first aspect, the Fresnel lens layer (23) for deflecting the traveling direction of the image light and the light exit side with respect to the Fresnel lens layer are provided to transmit light. A light control layer comprising a light transmission part (322) and a light absorption part (323) for absorbing light, and a light diffusion layer (33) provided on the light output side of the light control layer and having a function of diffusing light The transmissive screen (10) is characterized in that the light transmitting portion and the light absorbing portion are alternately arranged along the screen surface of the transmissive screen.
Invention of Claim 3 is located in the back side of the transmissive screen (10) of Claim 1 or Claim 2, the light source part (70) which projects image light, and the said transmissive screen, The said light source And a mirror unit (80) that reflects the image light from the unit and projects it onto the light incident surface (10a) of the transmissive screen.

  ADVANTAGE OF THE INVENTION According to this invention, display defects, such as a ghost, can be reduced significantly and it can be set as a transmissive screen which can display a favorable image | video, and a rear projection type display apparatus provided with the same.

It is a figure explaining the rear projection type display apparatus 1 of embodiment. 1 is a perspective view of a transmissive screen 10 according to an embodiment. It is a figure explaining the layer structure of the transmissive screen 10 of embodiment. It is a figure explaining the Fresnel lens layer 23 of embodiment. It is a figure explaining the light control layer 32 of embodiment. It is a figure explaining the effect | action of the light-incidence side functional layer. It is a figure which shows an example of the deformation | transformation form of the laminated body.

Embodiments of the present invention will be described below with reference to the drawings. In addition, each figure shown below including FIG. 1 is the figure shown typically, and the magnitude | size and shape of each part are exaggerated suitably for easy understanding.
In addition, the terms “plate”, “sheet”, “film” and the like are used, but these are generally used in the order of thickness, “plate”, “sheet”, “film”. I am using it. However, since there is no technical meaning in such proper use, the description in the claims is used in the unified description of the sheet. Accordingly, the terms “sheet”, “plate”, and “film” can be appropriately replaced.
Furthermore, numerical values such as dimensions and material names of each member described in the present specification are examples of the embodiment, and the present invention is not limited thereto, and may be appropriately selected and used.

(Embodiment)
FIG. 1 is a diagram illustrating a rear projection display device 1 of the present embodiment. FIG. 1 schematically shows a cross section of the rear projection display device 1 parallel to the depth direction and parallel to the vertical direction.
The rear projection display device 1 includes a transmissive screen 10, a light source unit 70, a mirror unit 80, and a housing 90. The rear projection display device 1 reflects the image light L projected from the light source unit 70 by the mirror unit 80 and projects the image light L to the rear side of the transmissive screen 10 to display an image on the transmissive screen 10.
The rear projection display device 1 of the present embodiment is used in an environment where the influence of outside light such as sunlight or illumination light is large. For example, the interior of an automobile or a ship (for example, a driver's seat or an engine) It is a rear projection display device for in-vehicle use or marine use arranged in a room or the like. In the present embodiment, the rear projection display device 1 will be described by taking as an example a small display screen having a screen size (screen size of the transmissive screen 10) of about 6 to 30 inches diagonal.
However, the present invention is not limited to this, and the rear projection display device 1 of the present embodiment can be used in an environment where the influence of external light is not so great, such as indoors, and the screen size is the same as that described above. It may be larger than that.

As shown in FIG. 1, the transmissive screen 10 has a curved shape that is uneven on the viewer O side (the image light output side). Details of the transmission screen 10 will be described later. The light source unit 70 is a video source that projects the video light L onto the transmissive screen 10. In the present embodiment, the light source unit 70 may be a small light source such as an LED (Light Emitting Diode) or a pico projector using a laser.
As shown in FIG. 1, the light source unit 70 of the present embodiment is disposed below the back side of the transmissive screen 10.

The mirror unit 80 is a reflecting mirror that is located on the back side of the transmissive screen 10, reflects the video light L projected by the light source unit 70, and projects the image light L onto the transmissive screen 10 from the back side.
In the present embodiment, an example in which the mirror unit 80 is a single reflecting mirror has been described. However, the present invention is not limited to this. For example, two or more mirrors may be used.
In addition, a reflection magnifying mirror or the like may be used as the reflection mirror used in the mirror unit 80.
The housing 90 supports the transmissive screen 10 and can arrange the light source unit 70 and the mirror unit 80 therein. The housing 90 has a light shielding property, and can prevent unnecessary external light such as illumination light and sunlight from entering from the back side of the transmissive screen 10. Further, from the viewpoint of absorbing and reducing stray light and the like, the inside of the housing is preferably a dark color system such as black.

FIG. 2 is a perspective view of the transmission screen 10 of the present embodiment. In FIG. 2, only the transmission screen 10 is shown in a simplified manner for easy understanding.
As shown in FIG. 2, the transmissive screen 10 has a curved shape such that the screen surface forms a three-dimensional curved surface when viewed as a whole. The transmissive screen 10 may have a curved shape such that the screen surface forms a two-dimensional curved surface.
Here, the screen surface is a surface direction that becomes a screen (display surface) of the transmissive screen 10 when viewed as the entire transmissive screen 10. A “two-dimensional curved surface” is one that is curved two-dimensionally around a single axis, or one that is curved two-dimensionally with different curvatures around a plurality of parallel axes. The term “three-dimensional curved surface” means a portion that is partially or wholly curved around a plurality of axes that form an angle with respect to each other.

As shown in FIG. 2, the transmissive screen 10 of the present embodiment has a first axis A <b> 1 that is parallel to one of the diagonal lines when viewed from the front direction and is located on the back side (light incident side) of the transmissive screen 10. Centered on a second axis A2 which is curved in a direction B1 centered on the viewer side so as to be convex on the viewer side (light emission side) and which is parallel to the other diagonal line and located on the back side of the transmission screen 10 It is curved so as to be convex toward the viewer in the direction B2.
On the display surface (light-emitting surface) of the transmissive screen 10, the point C (the point where a pair of rectangular diagonal lines forming the planar shape of the transmissive screen 10 intersects) that is the geometric center of the display area is the most observed. It has a form protruding to the person side. Note that the transmission screen 10 may be configured such that the point that protrudes most toward the viewer is different from the point C.
The transmissive screen 10 is a plane orthogonal to the normal direction N at the point C that is the most convex on the viewer side (light exit surface) (that is, the most convex on the viewer side). The contact surface at the point C) is parallel to the vertical direction (up and down direction of the screen).
In such a transmissive screen 10, the curvature radius of the curved shape depends on the screen size, but is preferably 2000 mm or less, more preferably 250 mm or more and 1500 mm or less.

In the present embodiment, the transmissive screen 10 has an example in which the screen surface (display surface) has a curved shape that protrudes toward the viewer side (light output side). It may have a curved shape that is convex (that is, concave toward the viewer) on the (incident side). Moreover, it is good also as a shape which combined the part which becomes convex on the observer side, and the part which becomes convex on the light source side.
In addition, an example in which the first axis A1 and the second axis A2 serving as curved axes are parallel to a rectangular diagonal line of a screen (display surface) when the transmission screen 10 is viewed from the front direction. Although not limited to this, when the transmissive screen 10 is viewed from the front direction, it passes through the point C, which is the geometric center of the observation screen, and is parallel to the screen vertical direction and parallel to the screen horizontal direction. The directions may be the first axis and the second axis, respectively.

FIG. 3 is a diagram illustrating the layer configuration of the transmission screen 10 of the present embodiment.
In FIG. 3, a part of a cross section passing through the point C of the transmissive screen 10 and parallel to the vertical direction of the screen and the thickness direction is shown enlarged.
As shown in FIG. 3, the transmissive screen 10 of the present embodiment is positioned on the light source side (light incident side, back side) and the observer side (light exit side) in the thickness direction. The laminated body 30 is provided.

The Fresnel lens sheet 20 is projected from the light source unit 70, reflected by the mirror unit 80 and incident on the Fresnel lens sheet 20 from the light incident side (back side), and deflected toward the viewer side in a substantially front direction N. It has a function to make the light beam to travel.
The Fresnel lens sheet 20 includes a light incident side functional layer 21, a Fresnel base material layer 22, and a Fresnel lens layer 23 in this order from the light incident side (back side), and these are integrally laminated.
In the present embodiment, the light incident surface of the Fresnel lens sheet 20 is the light incident surface 10 a of the transmissive screen 10.

The light incident side functional layer 21 is a layer provided on the most light incident side, and has a function of greatly reducing the amount of light reflected when entering the Fresnel lens sheet 20 (transmission type screen 10).
The light incident side functional layer 21 is a layer formed of a thin film of an inorganic compound (mainly an oxide or fluoride of an inorganic material). The light incident side functional layer 21 can reduce the amount of reflected light on the light incident surface 10a of the transmissive screen 10 (Fresnel lens sheet 20) by using optical interference and improve the transmittance of image light. .

The light incident side functional layer 21 is a layer in which a low refractive index layer (not shown) and a high refractive index layer (not shown) having a higher refractive index than the low refractive index layer are alternately stacked in order from the light incident side. Alternatively, the low refractive index layer may be located on the light incident side, and the high refractive index layer may be provided on the light exit side, or a layer having only the low refractive index layer may be used.
When the light incident side functional layer 21 is formed by alternately arranging a plurality of low refractive index layers and high refractive index layers, the low refractive index layer is provided at the most light incident side of the light incident side functional layer 21. Is preferably located.

The low refractive index layer is a layer having a refractive index lower than that of the layer (in this embodiment, the Fresnel base material layer 22) or a high refractive index layer located on the light output side of this layer. This low refractive index layer can be formed of, for example, silicon dioxide (refractive index: about 1.47), magnesium fluoride (refractive index: about 1.38), or the like.
The high refractive index layer has a higher refractive index than the low refractive index layer, and can be formed of, for example, titanium oxide (refractive index of about 2.55), zirconium oxide (refractive index of about 2.05), or the like.
Both the high refractive index layer and the low refractive index layer of the light incident side functional layer 21 are formed by a vacuum deposition method, a sputtering method, or the like.

The thickness of the low refractive index layer is d (nm), where n is the refractive index of the low refractive index layer, m is a positive odd number, and λ (nm) is the wavelength of light. It is preferable to satisfy.
d = m × λ / (4 × n) (Formula 1)
Here, m is preferably 1, and λ is preferably 450 to 580 nm.
By setting the thickness to satisfy the above formula 1, reflection of light can be effectively reduced and the transmittance can be improved.
The light incident side functional layer 21 includes an intermediate refractive index layer having an intermediate refractive index between the high refractive index layer and the low refractive index layer, and this is disposed between the low refractive index layer and the high refractive index layer. It is good also as a form.

The Fresnel base material layer 22 is a layer that becomes a base material of the Fresnel lens sheet 20, and is disposed on the light exit side of the light incident side functional layer 21. For the Fresnel base material layer 22, a resin-made sheet-like member having optical transparency can be used.
The Fresnel base material layer 22 is, for example, polycarbonate (PC) resin, polyethylene terephthalate (PET) resin, methyl methacrylate / butadiene / styrene (MBS) resin, methyl methacrylate / styrene (MS) resin, acrylonitrile / butadiene. A sheet-like member made of styrene (ABS) resin or the like can be used.
Moreover, although the thickness of the Fresnel base material layer 22 is based also on the screen size of the transmissive screen 10, it is preferable to set it as 1.0-4.0 mm. If the thickness of the Fresnel base layer 22 is less than 1.0 mm, the rigidity is insufficient. If the thickness exceeds 4.0 mm, the image light emitted from the Fresnel lens sheet 20 and the Fresnel lens sheet 20 Deviation from the generated stray light is increased, and a double image is likely to be generated. Therefore, the above range is preferable.
The Fresnel base material layer 22 may contain a diffusing material that diffuses light, or may be formed by coextruding a layer that does not contain a diffusing material and a layer that contains a diffusing material.

The Fresnel lens layer 23 is formed on the light output side (observer side) of the Fresnel base material layer 22, and a Fresnel lens shape formed by arranging a plurality of unit lenses 231 on the light output side surface is formed. The Fresnel lens layer 23 has a function of deflecting the image light incident on the Fresnel lens sheet 20 in the substantially front direction (normal direction N of the tangent surface at the point C) and directing it toward the light output side.
FIG. 4 is a diagram illustrating the Fresnel lens layer 23 of the present embodiment. FIG. 4 shows a state in which the Fresnel lens layer 23 is viewed from the front side of the light emission side. In order to facilitate understanding, in FIG. 4, the Fresnel lens layer 23 is shown as a substantially planar shape.
The Fresnel lens layer 23 of the present embodiment has a refractive Fresnel lens shape on the light output side surface. As shown in FIG. 4, here, the Fresnel lens layer 23 will be described by taking an example in which the unit lens 231 has a circular Fresnel lens shape arranged concentrically with the point F as the center. It may have a linear Fresnel lens shape.

As shown in FIG. 4, a point F that is the center of a concentric circle in which the unit lenses 231 of this embodiment are arranged (that is, the optical center of the circular Fresnel lens shape) is the front direction (transmission type) of the Fresnel lens sheet 20. A screen passing through the point C2 (geometric center of the Fresnel lens sheet 20) on the light exit surface side corresponding to the point C when viewed from the front direction when viewed from the normal direction N) of the tangent surface at the point C of the screen 10 It is on a straight line parallel to the vertical direction and is located below the Fresnel lens sheet 20.
However, the present invention is not limited thereto, and the point F may be located on the Fresnel lens sheet 20 on a straight line passing through the point C2 and parallel to the screen vertical direction, or the geometric center of the Fresnel lens sheet 20 It may be located on C2 or may be set as appropriate.

  The Fresnel lens layer 23 is formed integrally with the Fresnel base material layer 22 using an ultraviolet curable resin such as urethane acrylate or epoxy acrylate. However, the present invention is not limited to this, and the Fresnel lens layer 23 may be formed using another ionizing radiation curable resin such as an electron beam curable resin. Further, in the case of having a linear Fresnel lens shape, the Fresnel lens layer 23 and the Fresnel base material layer 22 may be integrally formed by extruding a thermoplastic resin.

Returning to FIG. 3, the layer configuration of the stacked body 30 will be described.
The laminate 30 includes a substrate layer 31, a light control layer 32, a light diffusion layer 33, a colored layer 34, and a light output side functional layer 35 in order from the image light incident side. It is the shape laminated on.
Hereinafter, each layer of the laminate 30 will be described.
The substrate layer 31 is a layer having a function of increasing the rigidity of the transmissive screen 10. As this board | substrate layer, plate-shaped members made from resin etc. which have a light transmittance can be used.
The substrate layer 31 of the present embodiment is disposed on the light incident side (Fresnel lens sheet 20 side) in the thickness direction of the stacked body 30.
The substrate layer 31 may be a plate-like member formed by extruding acrylic resin, styrene resin, polyester resin, PC resin, acrylonitrile / styrene (AS) resin, or the like. In addition, the thickness of the substrate layer 31 is preferably about 1.5 to 5.0 mm from the viewpoint of ensuring sufficient rigidity as a screen, ease of curved surface processing, and the like.

FIG. 5 is a diagram illustrating the light control layer 32 of the present embodiment. FIG. 5A shows an enlarged part of the cross section of the light control layer 32 (part of the cross section parallel to the vertical direction of the transmissive screen 10 and parallel to the thickness direction). FIG. 5B shows an enlarged part of the light control layer 32 as viewed from the front direction on the viewer side (light output side). In FIG. 5, the light control layer 32 is shown as a flat plate for easy understanding.
The light control layer 32 includes a base material part 321, a light transmission part 322, and a light absorption part 323. As shown in FIG. 3, the light control layer 32 is integrally laminated on the viewer side (light emission side) of the substrate layer 31 via the bonding layer 36.

The base material portion 321 is a layer that becomes a base (base material) of the light control layer 32.
As the base material portion 321, for example, a sheet-like member having a thickness of 75 to 200 μm formed of PC resin, PET resin, TAC (triacetyl cellulose) resin, ABS resin, MBS resin, MS resin, or the like is used. be able to.

A plurality of light transmission parts 322 are arranged and formed integrally on the light output side (observer side) surface of the base material part 321.
As shown in FIG. 5, the light transmission part 322 has a columnar shape that protrudes toward the light output side, extends in the horizontal direction of the screen, and is arranged in a plurality in the vertical direction of the screen along the light output side surface of the base material part 321. ing. The light transmission part 322 has a cross-sectional shape parallel to the arrangement direction and parallel to the thickness direction of the transmission screen 10 as shown in FIG. A substantially trapezoidal shape with a bottom.
The light transmissive portion 322 of the present embodiment has an isosceles trapezoidal cross section, and is symmetrical in the screen vertical direction (arrangement direction) as shown in FIG.

The light transmission part 322 is formed of a resin having light transmittance. The light transmission part 322 of the present embodiment is formed by an ultraviolet molding method using an ultraviolet curable resin such as urethane acrylate, but is not limited thereto, and other ionizing radiation curable resins such as an electron beam curable resin. May be formed.
The light transmission part 322 may be formed by a hot melt extrusion molding method using a thermoplastic resin such as a PET resin. If the light transmission part 322 has sufficient thickness, rigidity, etc., It is good also as a form which does not provide the material part 321. FIG.

As shown in FIG. 5A, the light absorbing portion 323 is a portion that is formed in a valley between adjacent light transmitting portions 322 and has an action of absorbing light.
As shown in FIG. 5B, the light absorbing portion 323 extends in the horizontal direction of the screen, and is alternately arranged in the vertical direction of the light transmitting portion 322 along the light output side surface of the light control layer 3. It has become a form. Further, the light output side surface of the light control layer 32 is formed by the light output side surface of the light transmitting portion 322 and the light output side surface of the light absorbing portion 323.
The light absorbing portion 323 has a wedge-shaped cross section in a cross section parallel to the arrangement direction and parallel to the thickness direction of the transmission screen 10.
Here, the wedge shape refers to a shape in which one end is wide and gradually narrows toward the other, and includes a triangular shape, a trapezoidal shape, and the like. Therefore, as shown in FIG. 5A, the light absorbing portion 323 has a substantially trapezoidal cross-sectional shape with the observer side (light emission side) as the bottom and the light source side (light incident side) as the top bottom. Or it is good also as a substantially triangular shape which makes the light source side the vertex.

The light absorbing portion 323 of this embodiment is filled with a light-transmitting resin containing a light absorbing material such as black beads by wiping (squeezing) the valleys between the light transmitting portions 322, and curing the resin. Is formed.
Examples of the light-transmitting resin used for the light absorbing portion 323 include ultraviolet curable resins such as urethane acrylate and epoxy acrylate, and ionizing radiation curable resins such as electron beam curable resins.
The light absorbing material used for the light absorbing portion 323 is a particulate member having a function of absorbing light in the visible light region, for example, metal salts such as carbon black, graphite, black iron oxide, pigments and dyes, Resin particles colored with pigments or dyes. When resin particles colored with pigments or dyes are used, the resin particles are formed of acrylic resin, PC resin, PE (polyethylene) resin, PS (polystyrene) resin, MBS resin, MS resin, or the like. Things can be used.

The refractive index of the light absorbing portion 323 is preferably smaller than the refractive index of the light transmitting portion 322 from the viewpoint of light beam control of image light. Accordingly, the light-transmitting resin used for the light absorbing portion 323 preferably has a refractive index smaller than that of the resin forming the light transmitting portion 322.
Note that the refractive index of the light absorbing portion 323 may be the same as the refractive index of the light transmitting portion 322 or may be larger than the refractive index of the light transmitting portion 322 according to the optical performance to be obtained. May be set.

  As shown in FIG. 5A, the arrangement pitch of the light transmission portions 322 (light absorption portions 323) is P1, the thickness of the light transmission portions 322 is D1, and the upper bottom of the light transmission portions 322 in the arrangement direction. The dimension of W1 is W1, the dimension of the lower base of the light absorbing portion 323 in the arrangement direction is W2, and the dimension of the upper base is W3. The dimension of the light absorption part 323 in the thickness direction is H1, and the angle formed by the interface between the light transmission part 322 and the light absorption part 323 and the thickness direction of the transmission screen 10 is θ.

The light control layer 32 can absorb the external light G incident from the observer side by the light absorbing portion 323, and can improve the contrast of the image. Further, the light absorbing unit 323 can absorb stray light generated in the screen.
Furthermore, when the refractive index of the light transmission part 322 is larger than the refractive index of the light absorption part 323, the image light L incident on the interface between the light transmission part 322 and the light absorption part 323 at an angle greater than the critical angle is Since the light is totally reflected at the interface and travels toward the light output side, the light control layer 32 can efficiently direct the image light into the viewing angle range on the light output side, and can display a bright image with high brightness.

Returning to FIG. 3, the light diffusion layer 33 is a layer having a function of diffusing light. The light diffusion layer 33 is disposed on the observer side (light emission side) of the light control layer 32. The light diffusion layer 33 of the present embodiment has an action of diffusing light isotropically.
The light diffusing layer 33 can be a sheet-like member in which a light diffusing material is contained in a light transmissive resin.
Examples of the light-transmitting resin that becomes the base material of the light diffusion layer 33 include MBS resin, acrylic resin, PC resin, and PET resin.
Moreover, as a diffusing material, it is an organic filler such as plastic beads, and a material having high transparency is particularly preferable. As such plastic beads, particles such as melamine resin, acrylic resin, AS resin, and PC resin can be applied. Silicon-based beads can also be used as a diffusing material. Furthermore, these light diffusing materials can be appropriately selected according to the desired diffusion performance and the like, and can be used by combining them at a predetermined ratio. For example, it is preferable to use a diffusing material having an average particle size of about 1 to 30 μm.

  The thickness of the light diffusion layer 33 is preferably 0.05 to 2.0 mm. If the thickness of the light diffusion layer 33 is less than 0.05 mm, the light diffusion effect may be insufficient, and if it exceeds 2.0 mm, the image displayed on the transmissive screen 10 is blurred and the resolution May be reduced. Therefore, the thickness of the light diffusion layer 33 is preferably within the above range.

The colored layer 34 is a sheet-like member that is provided on the light output side (observer side) with respect to the light diffusion layer 33 and is colored with a predetermined color and density. The colored layer 34 has a function of absorbing external light incident on the transmissive screen 10 from the observer side, a function of absorbing stray light generated in the transmissive screen 10, and the like.
The colored layer 34 is formed of a transparent resin containing a light absorbing material or a colorant. As the transparent resin used as the base material of the colored layer 34, MBS resin, acrylic resin, PC resin, PET resin, or the like can be used. The light absorbing material contained in the colored layer 34 is a metal salt such as carbon black, graphite, or black iron oxide, and the colorant is a dark dye or pigment such as gray or black. Can be used.

  The colored layer 34 preferably has a thickness of 10 to 200 μm. If the thickness of the colored layer 34 is less than 10 μm, the action of absorbing external light or the like may be insufficient. Further, when the thickness of the colored layer 34 exceeds 200 μm, the transmittance of the image light is lowered, and it is necessary to increase the output of the light source unit 70, which may increase power consumption. Therefore, the thickness of the colored layer 34 is preferably within the above range.

  The colored layer 34 and the light diffusion layer 33 of the present embodiment are integrally formed by coextrusion molding, and no bonding layer or the like is provided between the colored layer 34 and the light diffusion layer 33. However, the present invention is not limited thereto, and the colored layer 34 and the light diffusing layer 33 may be separately molded and laminated in the laminated body 30 via a bonding layer (not shown) or the like. The position within 30 may also be changed as appropriate.

The light output side functional layer 35 is a layer arranged on the most light output side (observer side) of the transmissive screen 10. The light output side functional layer 35 is a layer having at least one function such as a hard coat function, an antireflection function, an antistatic function, an ultraviolet absorption function, and an antifouling function.
The light output side functional layer 35 of the present embodiment has a hard coat function, and has a hardness of “2H” or more in a pencil hardness test defined by JIS K5600-5-4 (1994). For example, the light emitting side functional layer 35 is formed by applying an acrylic ultraviolet curable resin having a hard coat function or an acrylic thermosetting resin to the light emitting side of the colored layer 34 and curing the resin. Is formed.

The bonding layer 36 is a layer that integrally bonds the layers constituting the transmissive screen 10. The bonding layer 36 of the present embodiment is provided between the light control layer 32 and the light diffusion layer 33 and between the light control layer 32 and the substrate layer 31, and these layers are bonded together.
The bonding layer 36 may be made of, for example, an ultraviolet curable acrylic resin or a pressure-sensitive adhesive acrylic resin whose adhesiveness is manifested by pressure.
The thickness of the bonding layer 36 is appropriately selected within a range of 10 to 100 μm according to the size and use environment of the transmission screen 10, the characteristics of the resin of each layer to be bonded, the characteristics of the resin used as the bonding layer, and the like. it can.

The transmissive screen 10 is formed as follows, for example.
First, the sheet-like Fresnel base material layer 22 is produced by extruding a thermoplastic resin or the like and cut into a predetermined size. Then, in a state where the ultraviolet curable resin is filled between the sheet-shaped Fresnel base material layer 22 and the mold for shaping the Fresnel lens shape, the ultraviolet curable resin is cured by irradiating ultraviolet rays, A substantially flat Fresnel lens sheet in which the Fresnel lens layer 23 is formed on one side of the Fresnel base material layer 22 is produced by an ultraviolet molding method for releasing from the mold.
Next, the substantially flat Fresnel lens sheet is heated and softened, and is curved to form a curved surface by pressing it onto a mold surface (not shown) having a predetermined curved shape so that the Fresnel lens layer 23 side is convex. .
A multilayer in which low-refractive index layers and high-refractive index layers are alternately arranged by vacuum deposition or the like on the surface of the concave curved surface (the other surface of the Fresnel base material layer 22) of the Fresnel lens sheet after the curved surface molding. A thin film having a structure (thickness of about 0.45 μm) is formed, and the light incident side functional layer 21 is formed. Thereby, the Fresnel lens sheet 20 having a curved surface shape is completed.

Thus, even if the Fresnel lens sheet 20 has a curved surface shape, the light incident side functional layer 21 is uniformly formed on the light incident side surface of the Fresnel lens sheet 20 by forming it by vapor deposition or sputtering. Can be formed with thickness. In the incident-side functional layer 21 that exhibits an antireflection effect using optical interference as in the present embodiment, if the thickness is non-uniform, the antireflection performance is degraded or unevenness occurs on the incident surface 10a. Light is reflected, which causes luminance unevenness and ghosting. Moreover, in such a light incident side functional layer 21, the accuracy and uniformity required for its thickness depends on the wavelength region of visible light, and therefore is several hundred nm. Therefore, it is difficult to uniformly form the light incident side functional layer 21 by a manufacturing method such as coating a material for forming the antireflection layer on the curved surface. However, in the present embodiment, the light incident side functional layer 21 can be formed by a vapor deposition method or a sputtering method and can have a uniform thickness, so that the luminance unevenness and the ghost as described above can be greatly reduced.
Moreover, in this embodiment, since the light-incidence side functional layer 21 can be formed in the light-incidence side surface of the Fresnel lens sheet 20 (Fresnel base material layer 22) which has a curved surface shape, it is a separate antireflection sheet in a Fresnel lens sheet. Can prevent cracks and uneven thickness of the anti-reflective sheet caused by following the curved surface shape of the Fresnel lens sheet, and uneven brightness and display due to such cracks and uneven thickness. Defects can be prevented.

On the other hand, the laminated body 30 first forms the substrate layer 31, the light control layer 32, the light diffusion layer 33, and the colored layer 34, respectively. Then, the substrate layer 31, the light control layer 32, the light diffusion layer 33, and the colored layer 34, which are each formed as a separate flat plate, are integrally laminated by the bonding layer 36 to form a laminated body.
Then, this laminate is softened by heating, and is molded into a curved surface by pressing it onto a mold surface (not shown) having a predetermined curved surface shape as described above so that the light output side functional layer 35 side is convex. A laminated body 30 is formed. In addition, it is preferable to use a vacuum forming method for this curved surface forming.
Then, the transmissive screen 10 is completed by arranging the curved body-formed laminate 30 on the viewer side of the curved Fresnel lens sheet 20.

The state of image light and external light on the transmissive screen 10 will be described.
In the transmissive screen 10 of the present embodiment, the video light L projected from the light source unit 70 is reflected by the mirror unit 80 and enters the transmissive screen 10.
At this time, since the transmissive screen 10 has the light incident side functional layer 21 having an antireflection function on the most light incident side, most of the image light L is incident on the light incident surface 10 a of the transmissive screen 10. The light enters the transmission screen 10 (Fresnel lens sheet 20) without being reflected.
Then, the image light L passes through the Fresnel lens sheet 20, is deflected and emitted in the front direction (normal direction N of the tangent surface at the aforementioned point C) by the Fresnel lens layer 23, and enters the laminated body 30. .

The image light L incident on the stacked body 30 is transmitted through the substrate layer 31 and incident on the light control layer 32, part of which is emitted as it is in the front direction, and part of the light transmission part 322 and the light absorption part 323. The light is diffused in the vertical direction of the screen by being totally reflected at the interface (see FIG. 5A). At this time, the angle θ is a predetermined value, and since the degree of diffusion in the vertical direction of the screen is small, the front luminance is not lowered and the diffusion in the vertical direction of the screen is not caused more than necessary.
Then, the image light L is further isotropically diffused by the light diffusion layer 33, passes through the colored layer 34 and the light output side functional layer 35, and exits to the viewer side.
On the other hand, external light G (see FIGS. 3 and 5) such as sunlight and illumination light incident on the transmission screen 10 from the observer side is partly absorbed by the colored layer 34, and part is a light absorbing part 323. Absorbed in. Therefore, a reduction in contrast due to external light such as illumination light can be greatly improved.

Here, the operation of the light incident side functional layer 21 will be described.
FIG. 6 is a diagram for explaining the operation of the light incident side functional layer 21. FIG. 6A shows the transmissive screen 10 of the present embodiment, and FIG. 6B shows a conventional transmissive screen 40 that does not include the light incident side functional layer 21. In FIG. 6, the shape of any transmissive screen is simplified.
As shown in FIG. 6B, in the transmissive screen 40 of the comparative example that does not include the light incident side functional layer 21, a part of the image light L1 is at a point t1 on the light incident surface 40a of the transmissive screen 40. When incident, a part of the image light L2 is reflected. The image light L2 is reflected again by the mirror unit 80, enters the point t2 on the light incident surface 40a of the transmissive screen 40, and travels toward the viewer. At this time, part of the image light L3 may be reflected at the point t2.
As the positions of the points t1 and t2 that are the incident points of the image lights L1 and L2 for displaying the same image are shifted, the emission points of the image lights L1 and L2 are also different. As a result, a ghost (double image) is visually recognized. And the video becomes unclear. Further, when light such as the image light L3 is incident on the transmissive screen 40 again, the ambiguity of the image is further increased.

On the other hand, as shown in FIG. 6A, the transmissive screen 10 of the present embodiment includes a light incident side functional layer 21 having an antireflection function. The incident light is incident without being reflected at a point t1 on the light incident surface 10a of the transmissive screen 10. Therefore, the light L2 reflected by the light incident surface 10a is greatly reduced, and the amount of transmitted light of the video light L1 can be increased. Furthermore, even if the image light L2 is incident on the transmission screen 10 again, the amount of light is so small that it is not visually recognized as a ghost.
Therefore, according to the present embodiment, the ghost (double image) is greatly improved, and a bright and clear image is displayed.

From the above, according to the present embodiment, a ghost (double image) can be reduced and a clear image can be displayed, and a bright image can be displayed by increasing the amount of transmitted light of the image light. In addition, according to the present embodiment, the amount of transmitted video light increases, so that power consumption can be reduced.
Furthermore, according to this embodiment, since the light absorption part 323 and the colored layer 34 are provided, a favorable image with high contrast can be displayed even in a bright room environment.
Furthermore, according to the present embodiment, since the light incident surface 10a of the transmissive screen 10 can be made substantially smooth, for example, an infrared light projection device that projects infrared light from the back side of the transmissive screen 10; An infrared touch panel or the like that is disposed on the back side of the transmissive screen 10 and includes an infrared light detection device that can detect infrared light reflected when the user touches the screen, and the like can be used. The position detection accuracy in the touch panel using such infrared rays can be maintained high. For example, in a transmissive screen provided with a mat shape on the light incident surface and provided with an antireflection function, the touch panel using such infrared rays is diffused by the mat shape of the light incident surface, so that the detection accuracy decreases. End up. However, according to this embodiment, since it does not have such a mat shape, a decrease in position detection accuracy can be suppressed.

(Comparison of Examples and Comparative Examples)
Here, the transmissive screen of the example of the transmissive screen 10 of the present embodiment and the transmissive screen of the comparative example were produced, and the occurrence of ghosts was compared visually.
The transmission screen of the example corresponds to the example of the transmission screen 10 of the present embodiment, and the transmission screen of the comparative example is different except that the Fresnel lens sheet 20 does not have a light incident side functional layer. Is the same shape as the transmission screen of the embodiment.
The layers common to the transmissive screens of the examples and comparative examples are as follows.
(Fresnel lens sheet)
Fresnel base material layer 22: made of MBS resin (refractive index 1.55), thickness 1.1 mm.
Fresnel lens layer 23: UV curable resin (refractive index after curing 1.55).

(Laminated body 30)
Light-emitting side functional layer 35: has a hard coat function. Acrylic UV curable resin, thickness 30 μm.
Colored layer 34: made of MBS resin (refractive index 1.55) containing a black pigment as a colorant, thickness 60 μm.
Light diffusion layer 33: MBS resin (refractive index of 1.55) containing silicon beads (refractive index of 1.41, average particle size of about 2 μm) and acrylic beads (refractive index of 1.50, average particle size of about 10 μm) as a diffusing material. ) Manufactured, thickness 160 μm.
Light control layer 32: The base material portion 321 is a PC resin film (refractive index 1.59) and a thickness of 150 μm. The light transmission part 322 is made of an ultraviolet curable resin (refractive index after curing of 1.55). The light absorption part 323 is made of an ultraviolet curable resin (refractive index of 1.49 after curing) of black beads (average particle diameter of about 4 μm). The total thickness of the light control layer 32 is 300 μm.
Substrate layer 31: PC resin plate, thickness 2 mm.
Bonding layer 36: made of ultraviolet curable resin.

The light incident side functional layer 21 provided in the transmissive screen of the example is as follows.
Light-incident-side functional layer 21: formed on the light-incident side surface of the Fresnel base material layer 22 with a vapor deposition film of an oxide compound. A thickness of 0.45 μm, a wavelength of 550 nm, and a reflectance of 0.5%.
The Fresnel lens sheet of the transmission screen of the comparative example does not include the light incident side functional layer 21 as described above.

The transmissive screens of the examples and comparative examples including the Fresnel lens sheet 20 and the laminate 30 as described above are manufactured, and are actually incorporated in the rear projection display device 1 to project the image light from the light source unit 70 and display. The observed image was visually observed from the front of the transmission screen, and the situation at the time of occurrence of the ghost (double image) was evaluated.
Ghost was observed in the transmission screen of the comparative example. However, in the rear projection display device including the transmission screen of the example, no ghost was observed and a good image was observed.

(Deformation)
The present invention is not limited to the embodiment described above, and various modifications and changes are possible, and these are also within the scope of the present invention.
(1) In this embodiment, the laminated body 30 is the light output side functional layer 35, the colored layer 34, the light diffusion layer 33, the bonding layer 36, the light control layer 32, the bonding layer 36, and the substrate layer 31 in this order from the observer side. However, the present invention is not limited to this, and the layer configuration and the like may be changed as appropriate according to the desired optical performance.
FIG. 7 is a diagram illustrating an example of a modified form of the stacked body 30. In FIG. 7, a part of the cross section similar to FIG. 3 is shown in an enlarged manner.
As illustrated in FIG. 7, the stacked body 30 includes, in order from the observer side, a light output side functional layer 35, a substrate layer 31, a bonding layer 36, a coloring layer 34, a light diffusion layer 33, a bonding layer 36, and a light control layer 32. It is good also as a form arrange | positioned and laminated | stacked integrally. At this time, the laminated body 30 has a light transmitting property, and the substrate layer 31 having a sufficient thickness is positioned closer to the viewer than the light control layer 32 or the like. Will improve.

  Moreover, in this embodiment, although the laminated body 30 showed the example provided with the light control layer 32, it is good not only as this but the form which is not provided with the light control layer 32, for example. For example, the laminated body 30 may have a form in which a substrate layer 31, a light diffusion layer 33, a colored layer 34, and a light output side functional layer 35 are laminated integrally, or a layer having an optical shape such as a lenticular lens layer. It is good also as a form which has. Further, instead of the laminated body 30, the unit lens is arranged in the horizontal direction on the light incident side, and the surface of the unit lens has a lenticular lens sheet or the like in which a colored layer is formed along the shape of the unit lens. Also good.

(2) In the present embodiment, the transmissive screen 10 has an example including the Fresnel lens sheet 20 and the laminated body 30. However, the present invention is not limited thereto, and includes, for example, a single optical member laminated integrally. A transmission screen may be used.
Furthermore, in this embodiment, for example, when the incident angle of the image light is small, the laminated body 30 itself as shown in FIGS. 3 and 7 may be used as the transmission screen.

(3) In the present embodiment, the light incident side functional layer 21 has an example having an antireflection function. However, the present invention is not limited to this, and in addition to the antireflection function, for example, an antistatic function, an antifouling function, etc. You may provide the function suitably.

(4) In the present embodiment, the light source unit 70 projects image light from the lower side in the vertical direction on the transmissive screen 10 as shown in FIG. 1 when the rear projection display device 1 is in use. However, the present invention is not limited to this. For example, the image light may be projected from the upper side in the vertical direction with respect to the transmissive screen 10, or the image light may be projected from the front direction on the back side. .

(5) In the present embodiment, the light-incident side functional layer 21 is formed of an inorganic compound vapor-deposited film or the like. However, the present invention is not limited to this, and a plurality of smile protrusions are regularly arranged on the surface. An antireflection film or the like that suppresses reflection of light may be used by having a structure and continuously changing the refractive index in the thickness direction of the light incident surface due to the minute protrusions.

(6) In the present embodiment, the example in which the light emitting side functional layer 35 is provided has been described. However, the present invention is not limited thereto, and the light emitting side functional layer 35 is not provided as long as the substrate layer 31 has sufficient scratch resistance. It is good also as a form. By setting it as such a form, there can exist effects, such as shortening of a production process and reduction of production cost.

(7) In the present embodiment, the colored layer 34 is coextruded with the light diffusion layer 33 and disposed on the viewer side of the light diffusion layer 33. However, the present invention is not limited to this example. 34 may be extruded as a single layer and provided between the light control layer 32 and the substrate layer 31 or between the light diffusion layer 33 and the light control layer 32.
In this embodiment, the example provided with the light-diffusion layer 33 and the colored layer 34 was shown, However, Not only this but the light-diffusion layer 33 is made to contain the light absorber and the coloring agent, and the colored layer 34 is provided. There may be no form.
In addition to the light diffusing layer 33, the colored layer 34 may contain a light diffusing material depending on the desired optical characteristics and the like.

(8) In this embodiment, the cross-sectional shape of the light transmission part 322 and the light absorption part 323 showed the example which is substantially isosceles trapezoid shape, but it is not restricted to this, For example, the screen of one light transmission part 322 In the vertical direction, the angle θ between the interface with the light absorbing portion 323 and the thickness direction of the sheet is such that the upper angle θ and the lower angle θ are different, that is, the light transmitting portion and the light absorbing portion are The shape may be asymmetric in the vertical direction of the screen.
Further, the angle θ may be changed in the arrangement direction (the screen vertical direction) of the light transmission part 322 and the light absorption part 323.
Furthermore, the cross-sectional shape of the light absorbing portion 323 may be a wedge shape in which the width on the light exit side is smaller than the width on the light incident side. In this case, the base material portion 321 may be positioned on the light output side of the light absorbing portion 323 and the light transmitting portion 322. In such a form, the contrast can be further improved. Moreover, the cross-sectional shape of the light absorption part 323 is good also as a rectangular shape.

(9) In the present embodiment, an example in which the light control layer 32 is a single layer has been shown. However, the present invention is not limited to this. For example, the light transmission unit 322 and the light absorption unit 323 extend in the vertical direction of the screen, and It is good also as a form further provided with the 2nd light control layer arranged in the left-right direction.

(10) In the present embodiment, the bonding layer 36 has been described with reference to an example that does not contain a colorant or a diffusing material. However, the present invention is not limited thereto, and the diffusing material, the colorant, An ultraviolet absorber or the like may be added.

  In addition, although this embodiment and modification can also be used in combination as appropriate, detailed description is abbreviate | omitted. Further, the present invention is not limited to the embodiment described above.

DESCRIPTION OF SYMBOLS 1 Rear projection type display apparatus 10 Transmission type screen 20 Fresnel lens sheet 21 Light incident side functional layer 22 Fresnel base material layer 23 Fresnel lens layer 30 Laminate 31 Substrate layer 32 Light control layer 33 Light diffusion layer 34 Colored layer 35 Light emission side function Layer 70 Light source unit 80 Mirror unit

Claims (3)

A transmissive screen that displays video by transmitting image light projected from one surface side to the other surface side,
The screen has a curved shape that forms a curved surface,
The light incident surface on which the image light is incident is substantially smooth,
Forming the light incident surface, and comprising a light incident side functional layer having an antireflection function,
The light incident side functional layer is formed of a vapor deposition film or a sputtered film of an inorganic compound,
A transmissive screen characterized by The transmissive screen according to claim 1,
A Fresnel lens layer that deflects the traveling direction of the image light;
A light control layer that is provided on the light output side of the Fresnel lens layer and includes a light transmission part that transmits light and a light absorption part that absorbs light;
A light diffusion layer provided on the light output side of the light control layer and having a function of diffusing light;
With
The light transmission portions and the light absorption portions are alternately arranged along the screen surface of the transmission screen;
A transmissive screen characterized by The transmission screen according to claim 1 or 2,
A light source unit for projecting image light;
A mirror unit located on the back side of the transmissive screen, reflecting the image light from the light source unit and projecting it onto the light incident surface of the transmissive screen;
A rear projection display device comprising:

Images