JP2015052641A - Reflection type screen and reflection type video projection system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reflection type screen configured to absorb much external light while efficiently providing video light to an observer.SOLUTION: A reflection type screen (10) for reflecting video light projected from a video source (2) to an observer side includes: a prism layer (15) in which a plurality of unit prisms (16) formed so as to be protruded to a side opposite to the video source side are arrayed; and a light absorption layer (20) arranged at the back side of the prism layer for absorbing light. The unit prisms of the prism layer each include a first inclined surface (16a) and a second inclined surface (16b) as surfaces inclined to a screen surface, and the first inclined surface totally reflects at least a part of the light from the video light to the second inclined surface, and the second inclined surface totally reflects the video light from the first inclined surface to the observer side.

Description

  The present invention relates to a reflective screen for reflecting light from an image source and providing it to an observer, and a reflective image projection system using the same.

The reflective screen is a screen for reflecting the projection light from a video source such as a projector and emitting it to the viewer side. Therefore, the reflection type screen is provided with means for reflecting light on the back side thereof. For example, in Patent Document 1, image light is reflected by an aluminum vapor deposition film.
In recent years, the size of an image projected on a reflective screen tends to increase, and there is a need for a reflective screen that can display a high-quality image with improved brightness, contrast, and the like even in a bright room.

JP-A-8-29875

  However, in the invention described in Patent Document 1, it is difficult to obtain high contrast because not only image light but also external light is reflected and most of the light is emitted toward an observer.

  In view of the above problems, the present invention has an object to provide a reflective screen having a configuration in which image light can be efficiently provided to an observer and a large amount of external light can be controlled so as not to cause a decrease in contrast. And In addition, a reflective video projection system using the same is provided.

  The present invention will be described below. In order to facilitate understanding of the present invention, reference numerals in the accompanying drawings are appended in parentheses, but the present invention is not limited to the illustrated embodiment.

  The invention according to claim 1 is a reflection type screen (10) for reflecting the image light projected from the image source (2) to the viewer side, and is formed so as to protrude on the opposite side to the image source side. A prism layer (15) in which a plurality of unit prisms (16) are arranged, and a light absorption layer (20) that absorbs light disposed on the back side of the prism layer. The first inclined surface (16a) and the second inclined surface (16b) are surfaces that are inclined with respect to the screen surface, and the first inclined surface converts at least part of light from the image light into the second inclined surface. The second inclined surface is a reflective screen that totally reflects the image light from the first inclined surface toward the viewer.

  According to a second aspect of the present invention, in the reflection type screen (10) according to the first aspect, the unit prism has a triangular cross section orthogonal to the direction in which the ridgeline extends, and one of the hypotenuses of the triangle is inclined first. A surface (16a) is formed, and one of the other oblique sides is formed by a second inclined surface (16b).

  According to a third aspect of the present invention, in the reflective screen (10) according to the first aspect, the unit prism has a quadrangular cross section perpendicular to the direction in which the ridgeline extends, and one of the hypotenuses of the quadrilateral is inclined first. The surface (16a) is formed, the second inclined surface (16b) is formed on one of the other oblique sides, and the surface forming the other one side is bonded to the light absorbing layer (20).

  According to a fourth aspect of the present invention, in the reflective screen (10) according to any one of the first to third aspects, the light is diffused and emitted to the viewer side of the second inclined surface (16b). A plurality of unit light diffusing sections (13) are arranged with an interval corresponding to the interval between the second inclined surfaces.

  The invention according to claim 5 is the image source (2) for emitting an image and the reflection according to any one of claims 1 to 4, wherein the image light from the image source is reflected and emitted to the viewer side. A reflective video projection system (1) comprising a mold screen (10).

  According to the present invention, outside light is controlled so as not to cause a decrease in contrast while efficiently providing image light to an observer, and as a result, has high contrast.

It is a figure explaining a 1st form and is a perspective view of the reflection type video projection system. It is sectional drawing along the line shown by II-II in FIG. It is a figure explaining one form which looked at the light-diffusion layer 12 and the prism layer 15 from the back side. It is a figure explaining the other form which looked at the light-diffusion layer 12 and the prism layer 15 from the back side. FIG. 3 is an enlarged view of a part of the light diffusion layer 12 and the prism layer 15 in the reflective screen 10. It is a figure explaining a 2nd form and is a figure equivalent to FIG. It is a figure explaining a 3rd form and is a figure equivalent to FIG.

  The above-described operation and gain of the present invention will be clarified from the following embodiments of the invention. Hereinafter, the present invention will be described based on embodiments shown in the drawings. However, the present invention is not limited to these forms. Note that the shapes formed on the reflective screen described below are actually very small, so in the drawings shown below, each shape is conceptually exaggerated and deformed for ease of viewing. ing. In addition, in the drawings, repeated symbols may be given to only some of them, and others may be omitted.

  FIG. 1 is a diagram illustrating one embodiment, and is a perspective view of a reflective video projection system 1. FIG. 2 shows a cross-sectional view taken along the line II-II in FIG. As can be seen from FIGS. 1 and 2, the reflective image projection system 1 includes an image source 2 and a reflective screen 10. Each will be described below.

The video source 2 is a device that projects video light toward the reflective screen 10, and a known projector or the like can be used. As can be seen from FIGS. 1 and 2, in this embodiment, the image source 2 directs image light toward the reflective screen 10 obliquely at a position close to the reflective screen 10 below the center of the reflective screen 10. Project.
Thus, when image light is projected obliquely onto the reflective screen 10, the reflective screen in the normal direction of the screen surface of the reflective screen 10 (hereinafter sometimes simply referred to as "normal direction"). 10 and the image source 2 can be shortened. As a result, the lecturer or the like can make an explanation or the like while standing on the observing side of the image source 2, so that the image light emitted from the image source is not obstructed even when the lecturer and the like explain while moving.

The reflective screen 10 is a rectangular thin sheet as a whole, and is installed such that it is unfolded when used and the screen surface is set up in the vertical direction (vertical direction in FIG. 1). In order to ensure the flatness of the reflective screen 10 in use, it is preferable that the reflective screen 10 be attached to a support means (not shown) having a predetermined rigidity with an adhesive or the like. The support means may be a plate or a sheet-like member, but is not particularly limited as long as the posture of the reflective screen 10 can be maintained. Further, a flexible means may be used as the supporting means, and when it is not in use, it may be made compact by being rolled together with the reflective screen 10.
The reflective screen 10 functions as a screen by reflecting the image light projected from the image source 2 toward the viewer A (see FIGS. 1 and 2) in an unfolded posture.

  As can be seen from FIG. 2, the reflective screen 10 of this embodiment includes a base material layer 11, a light diffusion layer 12, a prism layer 15, a light absorption layer 20, and a surface functional layer 21. Each will be described below.

  The base material layer 11 in this embodiment is a sheet-like layer serving as a base material for the light diffusion layer 12, the prism layer 15, and the surface functional layer 21, and has a predetermined stiffness and is formed with high translucency. Although it will not specifically limit if it is such, For example, as a material which comprises the base material layer 11, a polyethylene terephthalate (PET), a polycarbonate (PC), methylmethacrylate butadiene styrene (MBS), an acrylic type, Examples of the resin include triacetyl cellulose (TAC). This form uses MBS from the viewpoints of availability, ease of handling, formability, and price. The thickness of the base material layer 11 is not particularly limited, and is preferably 100 μm or more and 300 μm or less in view of the balance between strength (windiness) and winding and rewinding.

  The light diffusion layer 12 is a layer that diffuses and emits light incident thereon. In this embodiment, the light diffusing layer 12 is a layer formed by incorporating a large number of light diffusing particles having a refractive index different from that of the light transmitting resin in the light transmitting resin. Due to this difference in refractive index, a large number of refractions and total reflections occur inside the light diffusion layer 12, and light is diffused.

  The resin used for the light-transmitting resin is not particularly limited as long as it is a light-transmitting resin that can disperse the light-diffusing particles and can hold the light-diffusing particles. Examples of such resins include thermoplastic resins such as polyamide resins, polyurethane resins, polyester resins, and acrylic resins, thermosetting resins, and active energy ray curable resins (ionizing radiation curable resins). .

  On the other hand, as light diffusion particles, crosslinked organic fine particles such as acrylic-styrene copolymer, polymethyl methacrylate, polystyrene, polyurethane, benzoguanamine, and melamine, resin fine particles such as silicone, and inorganic fine particles such as silica, alumina, and glass Etc. can be used.

Further, as can be seen from FIG. 2, the light diffusion layer 12 is arranged in accordance with the position of the second inclined surface 16 b in the front view among the unit prisms 16 described later. Accordingly, in the light diffusing layer 12, the unit light diffusing portions 13 having the intervals are also arranged corresponding to the intervals between the adjacent second inclined surfaces 16b. That is, the light diffusing layer 12 is configured by arranging a plurality of unit light diffusing portions 13 at intervals at a pitch corresponding to the pitch of the unit prisms 16. Thereby, the image light can be efficiently reflected to the viewer side and the viewing angle can be enlarged. Details will be described later.
The light diffusion characteristics of the light diffusion layer 12 may be isotropic or may have anisotropy (directivity). If it is isotropic, the viewing angle can be secured in all directions on the front side. On the other hand, for example, if the anisotropic characteristic is wide in the horizontal direction and narrow in the vertical direction, the amount of light traveling in the normal direction of the screen surface increases, so that it is bright when viewed from the normal direction. It becomes a screen.

  The prism layer 15 is a layer in which a plurality of unit prisms 16 provided so as to protrude on the opposite side (back side) of the base material layer 11 to the video source 2 side are arranged. In FIG. 3, the figure which looked at the prism layer 15 and the light-diffusion layer 12 from the back side was shown. As can be seen from FIG. 3, in the present embodiment, the plurality of unit prisms 16 are based on a so-called circular shape, the ridgelines of the unit prisms 16 extend in an arc shape, and the plurality of unit prisms 16 are arranged concentrically. In this embodiment, the center of the concentric circle is located below the screen and at the center in the horizontal direction of the screen.

  In the present embodiment, an example of such a circular shape is shown, but the present invention is not limited to this, and the ridgeline of the unit prism 16 may extend horizontally and linearly. FIG. 4 shows an example in which the ridgeline of the unit prism 16 is linear. FIG. 4 is from the same viewpoint as FIG. In the example shown in FIG. 4, the ridgelines of the unit prisms 16 extend horizontally, and the unit prisms 16 are arranged in a vertical direction that is a direction orthogonal to the direction in which the ridgelines extend.

  FIG. 2 shows a cross section perpendicular to the direction in which the ridgeline of the unit prism 16 extends. In this embodiment, the unit prism 16 has a triangular portion in this cross section. The unit prism 16 includes a first inclined surface 16a and a second inclined surface 16b that form two oblique sides of the triangle. FIG. 5 shows an enlarged view of part of the light diffusion layer 12, the prism layer 15, and the light absorption layer 20 in FIG.

  The first inclined surface 16 a and the second inclined surface 16 b are in contact with a substance having a low refractive index existing on the back side of the prism layer 15 to form an interface. In this embodiment, a gap is provided between the prism layer 15 and the light absorption layer 20, and the first inclined surface 16a and the second inclined surface 16b are in contact with air to form an interface. Since air has a low refractive index, it is advantageous in that a large refractive index difference is easily obtained at the interface, and the amount of light that can be totally reflected increases. However, if there is a situation where it is necessary to reduce the difference in refractive index from the viewpoint of the design of the reflective screen, a resin having a low refractive index is laminated on the first inclined surface 16a and the second inclined surface 16b to be refracted. The rate difference can be adjusted.

  The first inclined surface 16a is an inclined surface disposed on the image source 2 side of the unit prism 16, and is inclined at an angle α with respect to the direction along the sheet surface as shown in FIG. On the other hand, the second inclined surface 16b is disposed on the side of the unit prism 16 farther from the image source 2 than the first inclined surface 16a, and is inclined at an angle β with respect to the direction along the sheet surface. Specific values of the angle α and the angle β are appropriately set within a range in which an action described later can be realized. Details will be described later with an example of an optical path.

  The pitch of the unit prisms 16 is preferably 10 μm or more and 200 μm or less. If the pitch of the unit prisms 16 is too small, light is diffracted and rainbow colors are visible, which is undesirable. If the pitch is too large, each unit prism 16 may be distinguished and visually recognized. There is an undesirable appearance.

  The material forming the prism layer 15 is not particularly limited, but is widely used as a material for a reflective screen, and has excellent mechanical characteristics, optical characteristics, stability, workability, and the like, and can be obtained at low cost. It is preferable to use a material. Examples thereof include transparent resins mainly composed of one or more of acrylic, styrene, polycarbonate, polyethylene terephthalate, acrylonitrile, etc., and epoxy acrylate and urethane acrylate-based reactive resins (ionizing radiation curable resins, etc.). it can.

  The light absorption layer 20 is a layer disposed on the back side of the prism layer 15 and has a function of absorbing light. Such a light absorption layer 20 can be formed of a thermosetting resin containing a dark paint such as black, a pigment, a dye, beads having a light absorption function, or the like, or an ultraviolet curable resin. In this embodiment, the light absorption layer 20 is formed of a resin containing a black pigment.

  The surface functional layer 21 is a layer provided closer to the video source 2 than the base material layer 11. The surface functional layer 21 can be formed so as to have any one or more of an antireflection function, an antiglare function, an ultraviolet absorption function, an antifouling function, an antistatic function, and the like. A known method can be applied as means for providing such a function. For example, in order to have an antifouling function and an abrasion resistance function, an ionizing radiation curable resin such as urethane acrylate having a hard coat function is formed on the base layer 11 on the image source 2 side with a thickness of about 20 μm.

  The reflective screen 10 having the above-described configuration can be manufactured by a known method. For example, the light diffusion layer 12 is formed on one of the base material layers 11, and the prism layer 15 is further formed thereon. Then, the surface functional layer 21 is laminated on the other side of the base material layer 11. And the light absorption layer 20 is arrange | positioned among the prism layers 15 on the opposite side to the base material layer 11, and both four sides are fixed. Or you may hold | maintain, without fixing four sides, fixing only an upper side and hanging both.

  Next, in the reflective video projection system 1, the operation of the reflective screen 10 will be described with an example of the optical path. Moreover, the more preferable aspect of the structure demonstrated above in this is demonstrated. The path of light incident on the reflective screen 10 will be described with reference to the optical path examples L1, L2, and L3 shown in FIG. However, the optical path example shown in the figure conceptually represents the path of light, and does not accurately represent the degree of refraction or the angle of reflection.

The video light L1 projected from the video source 2 enters from below the reflective screen 10, passes through the surface functional layer 21 and the base material layer 11, and enters the unit prism 16 of the prism layer 15. Then, as shown in FIG. 5, the image light L1 reaches the first inclined surface 16a of the unit prism 16, is totally reflected, and is redirected toward the second inclined surface 16b. That is, the direction is changed in the direction along the sheet surface by the first inclined surface 16a.
Next, the image light L1 that has reached the second inclined surface 16b is also totally reflected here and brought closer to the normal direction, and the direction is changed so as to proceed to the observer side. Then, the light is diffused by the unit light diffusion portion 13 of the light diffusion layer 12 and reaches the observer. By diffusing light in this way, the viewing angle is widened and an image can be recognized over a wide range.

  On the other hand, external light (light from illumination, etc.) L2 and L3, which is light other than video light, is as follows. Outside light may be incident on the reflective screen 10 from all other angles, but light from the ceiling illumination (outside light L2) is considered to be the most important light among them. Further, since there is external light from a window or the like, light from the front (external light L3) is also taken into consideration.

  The external light L2 is assumed to be external light from the ceiling illumination, and enters the reflective screen 10 from obliquely above the reflective screen 10. The external light L2 is incident obliquely from above the reflective screen 10, passes through the surface functional layer 21 and the base material layer 11, and enters the unit prism 16 of the prism layer 15. As shown in FIG. 5, the external light L <b> 2 reaches the first inclined surface 16 a of the unit prism 16. However, the external light L2 passes through the interface due to the nature of the incident angle, reaches the light absorption layer 20 and is absorbed there. Therefore, the external light L2 does not reach the observer side and does not cause a decrease in contrast.

  Of the light incident on the reflective screen 10 from the ceiling illumination L3 or the external light, the external light that has reached the unit light diffusing unit 13 is diffused and travels in the direction of the back surface, but is diffused by the unit light diffusing unit 13. It reaches the first inclined surface 16a and the second inclined surface 16b at various angles. Among these, there is little light which is totally reflected by the 1st inclined surface 16a and the 2nd inclined surface 16b, and returns to an observer. Most of the light passes through the first inclined surface 16a and the second inclined surface 16b and is absorbed by the light absorption layer 20 as shown in FIG. Further, as shown in FIG. 5, even if the light is totally reflected by the first inclined surface 16 a and the second inclined surface 16 b and returns to the viewer side, it is inclined downward with respect to the normal direction of the reflective screen 10. Since it travels at a large angle, it does not reach the observer. Therefore, most of the external light incident on the reflective screen 10 does not reach the observer, so that the contrast of the projected image is not lowered and a high-contrast image can be obtained.

  In the reflective screen 10 acting as described above, it is preferable that the image light reaches the first inclined surface 16a and is totally reflected without being diffused as much as possible. Therefore, it is preferable that the unit light diffusion portion 13 of the light diffusion layer 12 is disposed only at a position overlapping the second inclined surface 16b in the front view of the reflective screen 10 as shown in FIGS. Moreover, it is preferable that the distance between the second inclined surface 16b and the unit light diffusion portion 13 is as close as possible. As a result, the degree to which the image light projected from the image source 2 is directly incident on the unit light diffusing unit 13 can be kept low. More specifically, as shown in FIG. 5, it is preferable that the one-end-type surface of the unit light diffusion portion 13 is disposed so as to contact the end portion on the valley side of the second inclined surface 16 b.

Further, the angle α and the angle β described above are not particularly limited as long as they act as described above, but can be considered as follows, for example.
When the image light projected from the image source 2 is incident on the unit prism 16 at an angle of θ (°) with respect to the normal line of the reflective screen 10 as shown in FIG. In order to perform total reflection whose direction is changed in a direction parallel to the surface of the reflective screen 10, when the refractive index of the material forming the unit prism 16 is N, the angle α (°) is α = ( 90 °-ARCSIN ((SINθ) / N)) / 2
Should be satisfied.

  In order to change the direction of the image light whose direction is changed parallel to the reflective screen 10 by the first inclined surface 16a to the normal direction of the reflective screen 10 by the second inclined surface 16b, β is set to 45. It should be °.

  As a more specific example, in the case of a projector generally projecting from obliquely below, θ, which is the incident angle to the prism layer 15, is 30 ° or more and 80 ° or less, so if N is 1.55, α is 25. What is necessary is just to set in the range of 3 to 35.6 degrees. At this time, the incident angle of the image light on the first inclined surface 16a is 54.4 ° or more and 64.7 ° or less, and a critical angle (ARSIN (1) when considering an interface with air (refractive index 1). /N))=40.18°). Therefore, it is clear that the image light is totally reflected at this time. Further, the incident angle on the second inclined surface 16b is constant at 45 °, which is also larger than the critical angle, so that it is clear that total reflection occurs here.

  As described above, according to the reflective screen 10, the image light is efficiently provided to the observer side, and most of the external light is absorbed and emitted so as not to reach the eyes of the observer. As a result, high contrast can be achieved.

FIG. 6 is a diagram for explaining the second embodiment, and a diagram corresponding to FIG. 2 is shown. In the second embodiment, a reflective screen 110 is applied. The reflective screen 110 is an example in which the light diffusion layer 112 is laminated on the surface of the base material layer 11 on the viewer side, and the surface functional layer 21 is provided via an air layer. Therefore, in this embodiment, the light diffusion layer 112 is provided on the viewer side with the base material layer 11 interposed therebetween, and the prism layer 15 is provided on the back surface side.
According to this embodiment, in the unit light diffusion portion 113 of the light diffusion layer 112, minute unevenness can be formed on the surface on the viewer side, and this can be used as the light diffusion means. Diffusion due to minute irregularities on the surface can diffuse light over a wider range than the unit light diffusion portion 13 described above.
Means for forming minute irregularities on the surface of the unit light diffusing portion 113 is well known. For example, a method of causing a part of the contained particles to protrude toward the observer can be exemplified.

  As for the light diffusion layer 112, the preferred form of the arrangement in the front view and the distance from the second inclined surface 16 b is the same as that of the light diffusion layer 12. Therefore, it is preferable that the base material layer 11 is as thin as possible from the viewpoint of reducing the distance between the light diffusion layer 112 and the second inclined surface 16b. In order to form the minute prism layer 15 and the light diffusion layer 112 on the thin base material 11 in this manner, the thin base material layer 11 and the thick base material are bonded together in advance with an adhesive layer, and the prism layer 15 or the light diffusion layer is then bonded. After forming 112, the thin base material layer 11 is peeled from the thick base material. Thereby, when forming the prism layer 15 or the light-diffusion layer 112, deformation | transformation of shapes, such as curvature and distortion, does not arise easily in the thin base material layer 11, and is preferable.

  FIG. 7 is a diagram for explaining the third embodiment, and a diagram corresponding to FIG. 5 is shown. In the third embodiment, a reflective screen 210 is applied. The reflective screen 210 is an example in which, in the prism layer 215, the ridgeline formed by the first inclined surface 16a and the second inclined surface 16b of the unit prism 216 is formed flat. Therefore, while the unit prism 16 has a triangular cross section, the unit prism 216 has a trapezoidal cross section with the back side being a short upper base and the observer side being a long lower base. And the surface which comprises a trapezoid leg part is the 1st inclined surface 16a and the 2nd inclined surface 16b. However, the concept of the form of the first inclined surface 16a and the second inclined surface 16b is the same as described above.

  According to the reflective screen 210, as shown also in FIG. 7, it can be bonded to the light absorption layer 20 with an adhesive or an adhesive at the upper bottom portion in the trapezoidal cross section. As a result, the reflective screen 210 can be more strongly integrated as a whole, as compared to fixing and integrating only four sides. If it is made thin as a whole, it becomes easy to make a roll-up type reflective screen. On the other hand, if it is thick as a whole, it can be maintained with good flatness.

DESCRIPTION OF SYMBOLS 1 Reflection type image projection system 2 Image source 10, 110, 210 Reflection type screen 11 Base material layer 12 Light diffusion layer 15 Prism layer 20 Light absorption layer 21 Surface functional layer

Claims (5)

A reflective screen that reflects image light projected from an image source to an observer side,
A prism layer in which a plurality of unit prisms formed so as to protrude on the side opposite to the image source side are arranged;
A light absorption layer that absorbs light disposed on the back side of the prism layer,
The unit prism of the prism layer is
Having a first inclined surface and a second inclined surface that are inclined with respect to the screen surface;
The first inclined surface totally reflects at least part of the light from the image light toward the second inclined surface, and the second inclined surface transmits the image light from the first inclined surface to the observer side. Total reflection towards
Reflective screen.   The unit prism has a triangular cross-section orthogonal to the direction in which the ridgeline extends, the first inclined surface forms one of the oblique sides of the triangle, and the second inclined surface forms one of the other oblique sides. The reflective screen according to claim 1.   The unit prism has a quadrangular cross section perpendicular to the direction in which the ridge line extends, the first inclined surface forms one of the oblique sides of the quadrangle, and the second inclined surface forms one of the other oblique sides, The reflective screen according to claim 1, wherein a surface forming still another side is bonded to the light absorption layer.   2. The plurality of unit light diffusing portions for diffusing and emitting light are arranged on the viewer side of the second inclined surface with an interval corresponding to the interval between the second inclined surfaces. 4. The reflective screen according to any one of 3 above. An image source that emits an image;
A reflective video projection system comprising: the reflective screen according to claim 1, wherein the video light from the video source is reflected and emitted to an observer side.

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