Image projection system and screen

Abstract

To allow switching of a projection surface of a screen with a simpler and more inexpensive configuration, while avoiding an image from being seen through from the opposite side of a surface on which the image is intended to be projected.SOLUTION: An image projection system 1 comprises: a screen 10; and one or more projection devices 20 that are arranged on one side of the screen 10 and emit certain type of polarized light. In the screen 10, a layer 11 in which first portions 11A formed of -45-degree 1 / 4 wavelength plates and second portions 11B formed of +45-degree 1 / 4 wavelength plates are alternately formed along a direction perpendicular to a light traveling direction, a layer 12 that has a polarization function with respect to a direction with a phase difference of +45 degrees or -45 degrees from a polarization direction of light from the projection devices 20, a layer 13 in which reflection portions reflecting and not transmitting light are formed only at positions corresponding to either one of the first portions 11A or the second portions 11B along the light traveling direction, and a layer 14 that prevents reflection of transmitted light while transmitting light through the back, are arranged in order from the upstream side along the light traveling direction.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to an image projection system that projects an image, and a screen that displays the image produced by projecting light. Note that in the following disclosure, the term "image" to be projected includes both moving images and still images. [Background technology]

[0002] In recent years, the use of components that separate spaces, such as window glass, walls, partitions, and blinds, as screens for projecting images has become widespread. For example, Non-Patent Document 1 proposes a window system that dynamically changes the transparency of a part of the window, Non-Patent Document 2 proposes a system that changes the transparency of a display to enable communication with the other side, and Non-Patent Document 3 introduces a product made of transparent glass screen. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] Publication: "Squama: a programmable window and wall for future physical architectures", by Junichi Rekimoto, Internet address: https: / / dl.acm.org / doi / abs / 10.1145 / 2370216.2370358 [Non-Patent Document 2] Paper "Tracs: transparency-control for see-through displays", by David Lindlbauer et al., Internet address: https: / / dl.acm.org / doi / 10.1145 / 2642918.2647350 [Non-Patent Document 3] Product information: "Glass transparent screen Glascene (registered trademark)", AGC Inc., Internet address: https: / / www.agc.com / products / new_markets / detail / transparent_glass_screen.html Summary of the Invention [Problem to be solved by the invention]

[0004] However, when an image is projected onto a transparent object such as a window pane, there is a concern that the image may be unintentionally seen from the opposite side of the projection surface.

[0005] Also, in relation to the above, techniques are known for projecting images onto both sides of a screen, rather than just one side. Although techniques for switching the projection surface of a screen when projecting an image can be achieved, for example, by installing projectors on both sides of the screen or by installing displays on both sides of the screen, there is a demand for a simpler and less expensive configuration.

[0006] Therefore, in consideration of the above circumstances, the present disclosure aims to make it possible to switch the projection surface of a screen using a simpler and less expensive configuration while avoiding an image from showing through to the opposite side of the surface to be projected. [Means for solving the problem]

[0007] The image projection system according to the present disclosure includes a screen for displaying an image produced by projected light, a first projection device arranged on one side of the screen, i.e., the front side, for emitting vertically polarized light or horizontally polarized light, or right-handed circularly polarized light or left-handed circularly polarized light, and a second projection device arranged on the front side for projecting light emitted by the first projection device. When the light is vertically or horizontally polarized, The light polarized in the direction perpendicular to the In the case where the light emitted by the first projection device is right-handed or left-handed circularly polarized light, the light is circularly polarized in the opposite direction to the right-handed or left-handed circularly polarized light. and a second projection device for projecting a light beam from the screen. The direction of the slow axis is a first direction perpendicular to the traveling direction of the projected light. A first portion formed of a quarter wave plate; The direction of the slow axis is the direction of travel of the projected light and a second direction perpendicular to the first direction.a first layer in which the first and second portions are alternately formed along a predetermined direction perpendicular to the direction of travel of the projected light; For light incident on the first layer having one polarization state, The above The polarized light transmits only one of the first polarized light emitted from the first portion and the second polarized light emitted from the second portion. a second layer having a polarizing function; a third layer having a reflective portion that reflects and does not transmit light at a position corresponding to one of the first portion or the second portion along the traveling direction of the projected light, and no reflective portion at a position corresponding to the other of the first portion or the second portion; and The light incident from the front side The light is transmitted to the rear side opposite to the front side, but reflected to the front side. and projected from the screen. Things to do teeth A blocking fourth layer is disposed in order from the upstream side along the direction of travel of the projected light.

[0008] The above-mentioned image projection system may include various polarization patterns. Here, as an example, the image projection system includes a first projection device that emits right-handed circularly polarized light for front projection, and a second projection device that emits left-handed circularly polarized light for rear projection. the first portion of the first layer emits vertically polarized light when right-handed circularly polarized light is incident thereon and emits horizontally polarized light when left-handed circularly polarized light is incident thereon; the second portion emits horizontally polarized light when right-handed circularly polarized light is incident thereon and emits vertically polarized light when left-handed circularly polarized light is incident thereon; The second layer is Transmits only vertically polarized light The operation will be described below assuming a configuration in which the third layer has a polarizing function, in which a reflective portion (a portion that reflects and does not transmit light) is formed at a position corresponding to the first portion in the first layer, and in which no reflective portion is formed at a position corresponding to the second portion in the first layer.

[0009] Right-handed circularly polarized light for front projection from the first projection device is projected onto the screen from the front side. The direction of the slow axis is the first direction perpendicular to the direction of the projected light. The light projected onto the second part of the first layer ( The direction of the slow axis is the direction of travel of the projected light and a second direction perpendicular to the first direction. The light projected onto the first portion of the first layer (the portion formed by the quarter-wave plate) is horizontally polarized light. Similarly, the left-handed circularly polarized light for rear projection from the second projector is also projected onto the screen from the front side, but the light projected onto the first portion of the first layer is horizontally polarized light, and the light projected onto the second portion of the first layer is vertically polarized light.

[0010] The second layer, as a function of the vertical polarization assumed above, transmits only vertically polarized light for front projection that has passed through the first portion and vertically polarized light for rear projection that has passed through the second portion, and absorbs other light.

[0011] In the third layer, a reflective portion is formed only at a position corresponding to the first portion in the first layer, so the "light for front projection" that has passed through the first portion and the second layer is reflected by the reflective portion in the third layer, and an image for front projection formed by that light is projected on the front of the screen. At this time, the reflective portion does not transmit light, so the image for front projection is prevented from being projected on the rear. Meanwhile, the "vertically polarized light for rear projection" that has passed through the second portion in the first layer and the second layer passes through a portion of the third layer where a reflective portion is not formed, and reaches the fourth layer.

[0012] The fourth layer transmits light to the rear side, so the "vertically polarized light for rear projection" transmits to the rear side, and the image for rear projection by that light is projected on the rear of the screen. Light entering from the front side is not reflected back to the front side This prevents the rear projection image from being projected onto the front.

[0013] Similarly, for patterns of polarization other than those described above, an image for front projection is projected onto the front surface of the screen without being transmitted to the rear surface, and an image for rear projection is projected onto the rear surface of the screen without being transmitted to the front surface. Details will be described in the embodiments of the invention.

[0014] As a result, it is possible to switch the projection surface of the screen with a simpler and less expensive configuration while preventing the image from showing through to the opposite side of the surface to be projected. More specifically, it is possible to switch the projection surface by arranging a projection device on one side of the screen without the need to arrange a projection device on both sides of the screen, and further, it is possible to prevent the image from showing through to the opposite side of the surface to be projected, and it can be realized at a lower cost than when displays are installed on both sides of the screen. Effect of the Invention

[0015] According to the present disclosure, it is possible to switch the projection surface of a screen with a simpler and less expensive configuration while preventing an image from showing through to the opposite side of the surface to be projected. [Brief description of the drawings]

[0016] [Figure 1] 1A and 1B are diagrams for explaining the configuration and operation of an image projection system in a first embodiment. [Diagram 2] FIG. 2 is a diagram for explaining the configuration of a patterned retarder layer. [Diagram 3] (a) is a diagram showing a first modified screen having a differently configured reflective layer, (b) is a diagram showing a second modified screen having a differently configured projection layer, and (c) is a diagram showing a third modified screen having a differently configured reflective layer and projection layer. [Figure 4] FIG. 1A is a diagram showing a first modified example of a projection device including a projector, a vertical polarizing plate, and a quarter-wave plate; FIG. 1B is a diagram showing a second modified example of a projection device including a projector, a liquid crystal plate, and a quarter-wave plate; and FIG. 1C is a diagram showing a third modified example of a projection device including a projector and a quarter-wave plate. [Diagram 5] 13A and 13B are diagrams for explaining the configuration and operation of an image projection system in a second embodiment. [Figure 6] (a) is a diagram showing a first modified screen having a differently configured reflective layer, (b) is a diagram showing a second modified screen having a differently configured projection layer, and (c) is a diagram showing a third modified screen having a differently configured reflective layer and projection layer. [Figure 7] FIG. 4 is a flowchart showing the operation of a control unit in the first and second embodiments. [Figure 8] FIG. 11A is a diagram for explaining the configuration of an image projection system in the third embodiment and the operation related to front projection, and FIG. 11B is a diagram for explaining the configuration of an image projection system in the third embodiment and the operation related to rear projection. [Figure 9] FIG. 11 is a flowchart showing the operation of a control unit in the third embodiment. [Figure 10] FIG. 2 illustrates an example of a hardware configuration of a control unit. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Various embodiments of an image projection system and a screen according to the present disclosure will be described below with reference to the drawings. Three embodiments will be described below, but first an overview of these embodiments will be provided.

[0018] The first embodiment is an embodiment relating to an image projection system including a screen and a projection device including a first projection unit that projects circularly polarized light for front projection and a second projection unit that projects circularly polarized light for rear projection. The second embodiment is an embodiment relating to an image projection system including a screen and a projection device including a first projection unit that projects vertically polarized or horizontally polarized light for front projection and a second projection unit that projects light for rear projection polarized in a direction perpendicular to the polarization direction of the light. The third embodiment is an embodiment relating to an image projection system including a screen and a single type of projection device that switches between light for front projection and light for rear projection and projects them.

[0019] [First embodiment] As shown in FIG. 1, the image projection system 1 in the first embodiment includes a screen 10 for displaying a projected image, and a projection device 20 provided on one side of the screen 10.

[0020] The projection device 20 includes at least one of a first projection device 20A arranged on one side (hereinafter referred to as the "front side") of the screen 10 and emitting vertically polarized or horizontally polarized light, or right-handed or left-handed circularly polarized light, and a second projection device 20B arranged on the front side and emitting light polarized in a direction perpendicular to the polarization direction of the light emitted by the first projection device 20A. In the first embodiment, a configuration example in which the projection device 20 includes both the first projection device 20A and the second projection device 20B, the first projection device 20A emits right-handed circularly polarized light, and the second projection device 20B emits left-handed circularly polarized light will be described. Specifically, the first projection device 20A includes a first projector 21A that emits unpolarized light and a right circular polarizer 22A provided on the emission side of the first projector 21A, and the second projection device 20B includes a second projector 21B that emits unpolarized light and a left circular polarizer 22B provided on the emission side of the second projector 21B. Note that the first projection device 20A and the second projection device 20B are not limited to being composed of one each, and each may be composed of a plurality of devices.

[0021] Moreover, the projection device 20 further includes a control unit 28 that incorporates an image DB 29 that stores image data of an image to be projected and supplies image data to the first projector 21A and the second projector 21B. Note that the control unit 28 is assumed to hold information regarding the image projection process to be executed (information indicating either front projection, rear projection, double-sided projection of the same image, or double-sided projection of different images) in advance, and determines the image projection process to be executed based on such information. In addition, in each of the first projection device 20A and the second projection device 20B described above, the projector and the circular polarizer do not necessarily need to be in contact with each other, and may be separated by a predetermined distance.

[0022] The screen 10 is composed of four layers: a patterned retarder layer 11, a polarizing layer 12, a reflective layer 13, and a projection layer 14. The above four layers are arranged in the following order from the light receiving surface side (left side in Figure 1) of the projected light along the thickness direction (left-right direction in Figure 1): patterned retarder layer 11, polarizing layer 12, reflective layer 13, and projection layer 14.

[0023] The patterned retarder layer 11 is composed of a first portion 11A made of a quarter-wave plate that imparts a phase difference of -45 degrees to the polarization direction of the projected light, and a second portion 11B made of a quarter-wave plate that imparts a phase difference of +45 degrees to the polarization direction of the projected light. Figure 2 shows the patterned retarder layer 11 as viewed from the left in Figure 1, and the first portion 11A and the second portion 11B are alternately formed along a direction (up and down direction in Figures 1 and 2) perpendicular to the traveling direction of the projected light (left and right direction in Figure 1).

[0024] The polarizing layer 12 is a layer having a polarizing function in a direction having a phase difference of +45 degrees or -45 degrees from the polarization direction of the projected light. As an example, the polarizing layer 12 in the first embodiment has a polarizing function in the vertical direction, which is a direction having a phase difference of +45 degrees from the polarization direction of the left-handed circularly polarized light from the second projector 20B.

[0025] The reflective layer 13 is a layer in which a reflective portion that reflects and does not transmit light is formed at a position corresponding to only one of the first portion 11A or the second portion 11B of the patterned retarder layer 11 along the traveling direction of the projected light. In the first embodiment, the reflective portion is formed at a position corresponding to only the first portion 11A of the patterned retarder layer 11. That is, the reflective portion of the reflective layer 13 is formed at a position corresponding to the first portion 11A along the depth direction of the paper surface in FIG. 2, but is not formed at a position corresponding to the second portion 11B. Note that the reflective portion of the reflective layer 13 may be configured to include, for example, a reflective member 13A made of a material that reflects light and an opaque member 13B made of a material that does not transmit light, as shown in FIG. 3(a).

[0026] The projection layer 14 is a layer that transmits light to the rear side of the screen 10, which is opposite to the front side, and prevents a part of the transmitted light from being reflected to the front side. For example, the projection layer 14 may be made of a material that transmits light but hardly reflects light, and the projection layer 14 can be simply configured. As another configuration example, as shown in FIG. 3(b), the projection layer 14 may be configured to include a quarter-wave plate 14A and a projection member 14B made of a material that transmits light. Among them, the quarter-wave plate 14A transmits right-polarized light by applying a phase difference of +45 degrees to the polarization direction of vertically polarized light that has passed through the polarizing layer 12 and the part of the reflective layer 13 where no reflective portion is formed, and then transmits horizontally polarized light to the front side by applying a phase difference of -45 degrees to the polarization direction of left-polarized light that has been reflected by the projection member 14B and has its polarization direction inverted. The horizontally polarized light that passes through is absorbed by the polarizing layer 12, which has a vertical polarization function, and is prevented from passing through to the front side. With this other configuration example, the vertical polarization function of the polarizing layer 12 can be effectively utilized to reliably prevent light reflected toward the front side from passing through to the front side.

[0027] Also, as shown in FIG. 3(c), the reflective layer 13 may be configured to include a reflective member 13A made of a material that reflects light and an opaque member 13B made of a material that does not transmit light, and the projection layer 14 may be configured to include a quarter-wave plate 14A and a projection member 14B made of a material that transmits light.

[0028] next, Figure 7 The processing operation in the image projection system 1 will be described with reference to FIG. 1. First, the control unit 28 determines whether the image projection processing to be executed is "front projection," "rear projection," "double-sided projection of the same image," or "double-sided projection of different images," and supplies image data according to the determination result. For example, the control unit 28 Figure 7In step S1 shown in FIG. 1, it is determined whether the image projection process to be executed is single-sided projection or not (double-sided projection), and if the answer is YES, it is determined in step S2 whether the process is single-sided projection, front projection or not (rear projection). On the other hand, if the answer is NO (double-sided projection) in step S1, it is determined in step S3 whether the process projects the same image or not (projects different images).

[0029] If the image projection process to be executed is front projection, the above steps S1 and S2 result in YES, and the process proceeds to step S4, where the control unit 28 supplies image data to be front projected to the first projector 21A. As a result, as shown by the solid line in Fig. 1, unpolarized light representing the image to be front projected is emitted from the first projector 21A, and the light right-circularly polarized by the right circular polarizer 22A reaches the screen 10.

[0030] At this time, the right-handed circularly polarized light that reaches the second portion 11B of the patterned retarder layer 11 becomes horizontally polarized light by the quarter-wave plate that imparts a phase difference of +45 degrees, and this horizontally polarized light is absorbed by the polarizing layer 12, which has a polarizing function in the vertical direction.

[0031] On the other hand, the right-handed circularly polarized light that reaches the first portion 11A of the patterned retarder layer 11 becomes vertically polarized light by the quarter-wave plate that imparts a phase difference of -45 degrees, and this vertically polarized light passes through the polarizing layer 12 having a polarizing function in the vertical direction, reaches the reflective portion of the reflective layer 13, and is reflected by this reflective portion to the front side without being transmitted to the rear side. As a result, an image formed by the above light (an image to be front-projected) is projected on the front side of the screen 10, while not being transmitted to the rear side. In other words, front projection is realized, and the image to be front-projected can be prevented from being seen through to the rear side.

[0032] If the image projection process to be executed is rear projection, the result is YES in step S1 and NO in step S2, and the process proceeds to step S5, where control unit 28 supplies image data to be rear projected to second projector 21B. As a result, as shown by the dashed line in Fig. 1, unpolarized light representing the image to be rear projected is emitted from second projector 21B, and the light that has been left-circularly polarized by left circular polarizer 22B reaches screen 10.

[0033] At this time, the left-handed circularly polarized light that reaches the first portion 11A of the patterned retarder layer 11 becomes horizontally polarized light by the quarter-wave plate that imparts a phase difference of -45 degrees, and this horizontally polarized light is absorbed by the polarizing layer 12, which has a polarizing function in the vertical direction.

[0034] On the other hand, the left circularly polarized light that reaches the second portion 11B of the patterned retarder layer 11 becomes vertically polarized light by the quarter-wave plate that gives a phase difference of +45 degrees, and this vertically polarized light passes through the polarizing layer 12 that has a polarizing function in the vertical direction. The light that passes through the polarizing layer 12 passes through a portion of the reflective layer 13 where no reflective portion is formed, and reaches the projection layer 14. Since the projection layer 14 transmits light to the rear side, the light for rear projection passes through to the rear side, and thus an image for rear projection by the light is projected on the rear surface of the screen 10. In addition, the projection layer 14 prevents a part of the light that passes through from being reflected to the front surface, so that the image for rear projection is prevented from being projected on the front surface. As a result, rear projection is realized and the image is prevented from being seen through to the front surface.

[0035] In the case of double-sided projection of images with different image projection processes to be executed, the results of steps S1 and S3 are NO, and the process proceeds to step S7, where the control unit 28 supplies image data to be front-projected to the first projector 21A and image data to be rear-projected to the second projector 21B. As a result, as shown by the solid line in FIG. 1, unpolarized light representing the image to be front-projected is emitted from the first projector 21A, and the light right-circularly polarized by the right circular polarizer 22A reaches the screen 10. At the same time, unpolarized light representing the image to be rear-projected is emitted from the second projector 21B, and the light left-circularly polarized by the left circular polarizer 22B reaches the screen 10. After that, both the operation related to step S4 and the operation related to step S5 described above are executed simultaneously, and as a result, both front projection and rear projection (i.e., double-sided projection) are realized, and it is possible to prevent the image of the front projection from showing through to the rear and the image of the rear projection from showing through to the front.

[0036] When the image projection process to be executed is double-sided projection of the same image, the result is NO in the above step S1 and YES in step S3, and the process proceeds to step S6, where the control unit 28 supplies image data to be front-projected to the first projector 21A and image data of a mirror image of the image to be front-projected to the second projector 21B. As a result, unpolarized light representing the image to be front-projected is emitted from the first projector 21A, and the light right-circularly polarized by the right circular polarizer 22A reaches the screen 10. At the same time, unpolarized light representing the mirror image of the image to be front-projected is emitted from the second projector 21B, and the light left-circularly polarized by the left circular polarizer 22B reaches the screen 10. After that, both the operation related to the above-mentioned step S4 and the operation related to step S5 are executed simultaneously, and as a result, both the front projection and the rear projection (i.e., double-sided projection) are realized, and it is possible to prevent the image of the front projection from showing through to the rear and the image of the rear projection from showing through to the front. Furthermore, at this time, a mirror image of the image projected on the front side is projected on the rear side, and the image seen from the rear side is the same as the image projected on the front side, thereby realizing double-sided projection of the same image.

[0037] According to the first embodiment described above, it is not necessary to place projection devices on both sides of the screen, but by placing two types of projection devices on one side of the screen, it is possible to freely switch between a total of four patterns: "front projection", "rear projection", "double-sided projection of the same image", and "double-sided projection of different images". In addition, it is possible to prevent an image from showing through to the opposite side of the surface to be projected, and this can be realized at a lower cost than when displays are placed on both sides of the screen.

[0038] The projection device 20 in the first embodiment is not limited to the configuration shown in FIG. Figure 4 (a) Figure 4 (b) Figure 4 The modified examples shown in (c) may be adopted. For example, Figure 4 As shown in (a), the first projection device 20A may include a first projector 21A that emits unpolarized light, a vertical polarizing plate 23 provided on the emission side of the first projector 21A, and a quarter-wave plate 24A that provides a phase difference of +45 degrees, and the second projection device 20B may include a second projector 21B that emits unpolarized light, a vertical polarizing plate 23 provided on the emission side of the second projector 21B, and a quarter-wave plate 24B that provides a phase difference of -45 degrees. With the above configuration, right-handed circularly polarized light is emitted from the first projection device 20A, and left-handed circularly polarized light is emitted from the second projection device 20B, similar to the configuration of FIG.

[0039] Another variation is: Figure 4As shown in (b), the first projection device 20A may include a first projector 21A that emits unpolarized light, a liquid crystal plate 25 that is a polarizing member provided on the emission side of the first projector 21A and electronically switches the polarization direction between vertical and horizontal, and a quarter-wave plate 24A that gives a phase difference of +45 degrees, and the second projection device 20B may include a second projector 21B that emits unpolarized light, a liquid crystal plate 25 that is a polarizing member provided on the emission side of the second projector 21B and electronically switches the polarization direction between vertical and horizontal, and a quarter-wave plate 24B that gives a phase difference of -45 degrees. The liquid crystal plate 25 can switch the polarization direction between vertical and horizontal by a control unit 28, and when the polarization direction of the liquid crystal plate 25 is switched to the vertical direction, for example, Figure 4 This can be considered to be the same configuration as the example including the vertical polarizer 23 in (a), where right-handed circularly polarized light is emitted from the first projection device 20A and left-handed circularly polarized light is emitted from the second projection device 20B. Also, instead of the liquid crystal plate that is a polarizing member that electronically switches the polarization direction between vertical and horizontal as described above, a polarizing member that mechanically switches the polarization direction between vertical and horizontal may be used. In this way, the degree of freedom in mounting can be increased.

[0040] Furthermore, as another modification, Figure 4 As shown in (c), the first projection device 20A may be configured to include a first projector 21A that emits vertically polarized light and a ¼ wavelength plate 24A that is provided on the emission side of the first projector 21A and provides a phase difference of +45 degrees, and the second projection device 20B may be configured to include a second projector 21B that emits vertically polarized light and a ¼ wavelength plate 24B that is provided on the emission side of the second projector 21B and provides a phase difference of -45 degrees. Figure 4 This can be considered to be the same as the configuration example (a), and right-handed circularly polarized light is emitted from the first projection device 20A, and left-handed circularly polarized light is emitted from the second projection device 20B. Figure 4 (a) Figure 4 (b) Figure 4 Various configurations shown in (c) can be adopted, which increases the degree of freedom in implementation.

[0041] [Second embodiment] Next, a second embodiment will be described. The second embodiment relates to an image projection system including a screen and a projection device including a first projector that projects vertically or horizontally polarized light for front projection and a second projector that projects light for rear projection polarized in a direction perpendicular to the polarization direction of the first projector.

[0042] Figure 5 As shown in FIG. 1, the image projection system 1 in the first embodiment includes a screen 10 for displaying a projected image, and a projection device 20 provided on one side of the screen 10. Here, as an example, the projection device 20 includes a first projector 21A that emits horizontally polarized light, a second projector 21B that emits vertically polarized light, and a control unit 28 that includes an image DB 29 similar to that in the first embodiment. Note that the first projector 21A and the second projector 21B are not limited to being composed of one each, and each may be composed of a plurality of units.

[0043] The screen 10 is composed of four layers: a patterned retarder layer 11, a circularly polarizing layer 12A, a reflective layer 13, and a projection layer 14. The above four layers are arranged on the light receiving side ( Figure 5 From the left side in the thickness direction ( Figure 5 Along the left-right direction in the figure, a patterned retarder layer 11, a circularly polarizing layer 12A, a reflective layer 13, and a projection layer 14 are arranged in this order. Among these, the configurations of the patterned retarder layer 11, the reflective layer 13, and the projection layer 14 are similar to those in the first embodiment, so duplicated descriptions will be omitted.

[0044] The circular polarization layer 12A has a polarizing function for directions with a phase difference of +45 degrees or -45 degrees from the polarization direction of the projected light. As an example, the circular polarization layer 12A in the second embodiment has a polarizing function for right-handed circularly polarized light, which is a direction with a phase difference of +45 degrees from the polarization direction of the vertically polarized light from the second projector 21B.

[0045] As in the first embodiment, in the reflective layer 13, the reflective portion is formed at a position corresponding only to the first portion 11A in the patterned retarder layer 11. The reflective portion in the reflective layer 13 is, for example, Figure 6 As shown in (a), the configuration may include a reflective member 13A made of a material that reflects light, and an opaque member 13B made of a material that does not transmit light.

[0046] As in the first embodiment, the projection layer 14 may be made of a material that transmits light but hardly reflects light. Figure 6 As shown in (b), the projection layer 14 may include a quarter-wave plate 14A and a projection member 14B made of a light-transmitting material. The quarter-wave plate 14A transmits horizontally polarized light by applying a phase difference of +45 degrees to the polarization direction of right-handed circularly polarized light that has passed through the circular polarization layer 12A and the non-reflective portion of the reflection layer 13, and then transmits left-handed circularly polarized light to the front side by applying a phase difference of -45 degrees to the polarization direction of vertically polarized light that has been reflected by the projection member 14B and has its polarization direction reversed. The left-handed circularly polarized light that has passed through here is absorbed by the circular polarization layer 12A, which has a polarizing function for right-handed circular polarization, and is prevented from transmitting to the front side.

[0047] Also, Figure 6 As shown in (c), the reflective layer 13 may include a reflective member 13A made of a material that reflects light and an opaque member 13B made of a material that does not transmit light, and the projection layer 14 may include a quarter-wave plate 14A and a projection member 14B made of a material that transmits light.

[0048] next, Figure 7 and Figure 5 The processing operation in the image projection system 1 of the second embodiment will be described with reference to the following. First, the control unit 28 judges whether the image projection processing to be executed is "front projection", "rear projection", "double-sided projection of the same image", or "double-sided projection of different images", and supplies image data according to the judgment result. For example, the control unit 28 Figure 7In step S1 shown in FIG. 1, it is determined whether the image projection process to be executed is single-sided projection (front projection or rear projection), and if the answer is YES, it is determined in step S2 whether the process is single-sided projection, front projection or not (rear projection). On the other hand, if the answer is NO (double-sided projection) in step S1, it is determined in step S3 whether the process projects the same image or not (projects different images).

[0049] If the image projection process to be executed is front projection, the results of steps S1 and S2 are YES, the process proceeds to step S4, and the control unit 28 supplies image data to be front-projected to the first projector 21A. Figure 5 As shown by the solid line in FIG. 1, horizontally polarized light representing an image to be front-projected is emitted from first projector 21A and reaches screen 10.

[0050] At this time, the horizontally polarized light that reaches the second portion 11B of the patterned retarder layer 11 becomes left-handed circularly polarized light by the quarter-wave plate that imparts a phase difference of +45 degrees, and this left-handed circularly polarized light is absorbed by the circular polarization layer 12A, which has a polarizing function for right-handed circular polarization.

[0051] On the other hand, the horizontally polarized light that reaches the first portion 11A of the patterned retarder layer 11 becomes right-handed circularly polarized light by the quarter-wave plate that imparts a phase difference of -45 degrees, and this right-handed circularly polarized light passes through the circular polarization layer 12A having a polarizing function for right-handed circular polarization, reaches the reflecting portion of the reflective layer 13, and is reflected by this reflecting portion to the front side without passing through to the rear side. As a result, the image of the above light (the image to be front-projected) is projected on the front side of the screen 10, while not passing through to the rear side. In other words, front projection is realized, and the image to be front-projected can be prevented from showing through to the rear side.

[0052] If the image projection process to be executed is rear projection, the result is YES in step S1 and NO in step S2, and the process proceeds to step S5, where control unit 28 supplies image data to be rear projected to second projector 21B. As a result, vertically polarized light representing the image to be rear projected is emitted from second projector 21B and reaches screen 10, as shown by the dashed line in FIG.

[0053] At this time, the vertically polarized light that reaches the first portion 11A of the patterned retarder layer 11 becomes left-handed circularly polarized light by the quarter-wave plate that imparts a phase difference of -45 degrees, and this left-handed circularly polarized light is absorbed by the circular polarization layer 12A, which has a polarizing function for right-handed circular polarization.

[0054] On the other hand, the vertically polarized light that reaches the second portion 11B of the patterned retarder layer 11 becomes right-handed circularly polarized light by the quarter-wave plate that gives a phase difference of +45 degrees, and this right-handed circularly polarized light passes through the circular polarization layer 12A that has a polarizing function of right-handed circular polarization. The light that passes through the circular polarization layer 12A passes through a portion of the reflective layer 13 where no reflective portion is formed, and reaches the projection layer 14. Since the projection layer 14 transmits light to the rear side, the light for rear projection passes through to the rear side, and thus an image for rear projection by the light is projected on the rear of the screen 10. In addition, the projection layer 14 prevents a part of the light that passes through from being reflected to the front side, so that the image for rear projection is prevented from being projected on the front. As a result, rear projection is realized and the image is prevented from being seen through to the front.

[0055] In the case where the image projection process to be executed is a double-sided projection of different images, the results of steps S1 and S3 are NO, the process proceeds to step S7, and the control unit 28 supplies image data to be front projected to the first projector 21A and image data to be rear projected to the second projector 21B. Figure 5As shown by the solid line in , horizontally polarized light representing an image to be front projected is emitted from first projector 21A and reaches screen 10. At the same time, vertically polarized light representing an image to be rear projected is emitted from second projector 21B and reaches screen 10. After that, the operation related to step S4 and the operation related to step S5 described above are both executed simultaneously, as a result, both front projection and rear projection (i.e., double-sided projection) are realized, and it is possible to prevent the front-projected image from showing through to the rear and the rear-projected image from showing through to the front.

[0056] If the image projection process to be executed is double-sided projection of the same image, the result is NO in the above step S1 and YES in step S3, and the process proceeds to step S6, where the control unit 28 supplies image data to be front-projected to the first projector 21A and image data of a mirror image of the image to be front-projected to the second projector 21B. As a result, horizontally polarized light representing the image to be front-projected is emitted from the first projector 21A and reaches the screen 10. At the same time, vertically polarized light representing the mirror image of the image to be front-projected is emitted from the second projector 21B and reaches the screen 10. After that, both the operation related to the above-mentioned step S4 and the operation related to step S5 are executed simultaneously, and as a result, both front projection and rear projection (i.e., double-sided projection) are realized, and it is possible to prevent the front-projected image from showing through to the rear and the rear-projected image from showing through to the front. Furthermore, at this time, the mirror image of the image to be front-projected is rear-projected, and the image seen from the rear becomes the same as the image to be front-projected, so that double-sided projection of the same image is realized.

[0057] According to the second embodiment described above, it is not necessary to place projection devices on both sides of the screen, but by placing two types of projection devices on one side of the screen, it is possible to freely switch between a total of four patterns: "front projection", "rear projection", "double-sided projection of the same image", and "double-sided projection of different images". In addition, it is possible to prevent an image from showing through to the opposite side of the surface to be projected, and this can be realized at a lower cost than installing displays on both sides of the screen.

[0058] [Third embodiment] Next, a third embodiment will be described regarding an image projection system including a single type of projection device that switches between light for front projection and light for rear projection and projects the light, and a screen.

[0059] 8(a), the image projection system 1 in the third embodiment includes a screen 10 for projecting a projected image, and a projection device 20 provided on one side (front side) of the screen 10. Here, as an example, the projection device 20 includes a projector 21 that switches between emitting horizontally polarized light for front projection and vertically polarized light for rear projection, and a control unit 28 that includes an image DB 29 similar to those in the first and second embodiments. Note that the projection device 20 is not limited to having a single projector 21, and may be configured with multiple units that perform the same operation.

[0060] As in the second embodiment, the screen 10 is composed of four layers: a patterned retarder layer 11, a circularly polarizing layer 12A, a reflective layer 13, and a projection layer 14. The above four layers are arranged in the following order from the light receiving surface side (the left side in FIG. 8(a)) of the projected light along the thickness direction (the left-right direction in FIG. 8(a)): the patterned retarder layer 11, the circularly polarizing layer 12A, the reflective layer 13, and the projection layer 14. The configuration of each of these four layers is the same as in the second embodiment, so a duplicated description will be omitted.

[0061] FIG. 8(a) shows a state in which horizontally polarized light for front projection is emitted from projector 21, reflected to the front side by screen 10, and projected onto the front, while FIG. 8(b) shows a state in which vertically polarized light for rear projection is emitted from projector 21, transmitted to the rear side by screen 10, and projected onto the rear.

[0062] Hereinafter, the processing operation in the image projection system 1 of the third embodiment will be described with reference to Fig. 8(a), Fig. 8(b) and Fig. 9. When the image projection process to be executed is "front projection" (YES in step S11), the control unit 28 supplies image data to be front projected to the projector 21 (step S12). As a result, in the configuration for front projection (Fig. 8(a)), horizontally polarized light representing the image to be front projected, shown by the solid line in Fig. 8(a), is emitted from the first projector 21A and reaches the screen 10.

[0063] At this time, the horizontally polarized light that reaches the second portion 11B of the patterned retarder layer 11 becomes left-handed circularly polarized light by the quarter-wave plate that imparts a phase difference of +45 degrees, and this left-handed circularly polarized light is absorbed by the circular polarization layer 12A, which has a polarizing function for right-handed circular polarization.

[0064] On the other hand, the horizontally polarized light that reaches the first portion 11A of the patterned retarder layer 11 becomes right-handed circularly polarized light by the quarter-wave plate that imparts a phase difference of -45 degrees, and this right-handed circularly polarized light passes through the circular polarization layer 12A having a polarizing function for right-handed circular polarization, reaches the reflecting portion of the reflective layer 13, and is reflected by this reflecting portion to the front side without passing through to the rear side. As a result, the image of the above light (the image to be front-projected) is projected on the front side of the screen 10, while not passing through to the rear side. In other words, front projection is realized, and the image to be front-projected can be prevented from showing through to the rear side.

[0065] 9, when the image projection process to be executed is "rear projection" (NO in step S11), control unit 28 supplies image data to be rear projected to projector 21 (step S13). As a result, in the configuration for rear projection (FIG. 8(b)), vertically polarized light representing the image to be rear projected, shown by the dashed line in FIG. 8(b), is emitted from projector 21 and reaches screen 10.

[0066] At this time, the vertically polarized light that reaches the first portion 11A of the patterned retarder layer 11 becomes left-handed circularly polarized light by the quarter-wave plate that imparts a phase difference of -45 degrees, and this left-handed circularly polarized light is absorbed by the circular polarization layer 12A, which has a polarizing function for right-handed circular polarization.

[0067] On the other hand, the vertically polarized light that reaches the second portion 11B of the patterned retarder layer 11 becomes right-handed circularly polarized light by the quarter-wave plate that gives a phase difference of +45 degrees, and this right-handed circularly polarized light passes through the circular polarization layer 12A that has a polarizing function of right-handed circular polarization. The light that passes through the circular polarization layer 12A passes through a portion of the reflective layer 13 where no reflective portion is formed, and reaches the projection layer 14. Since the projection layer 14 transmits light to the rear side, the light for rear projection passes through to the rear side, and thus an image for rear projection by the light is projected on the rear of the screen 10. In addition, the projection layer 14 prevents a part of the light that passes through from being reflected to the front side, so that the image for rear projection is prevented from being projected on the front. As a result, rear projection is realized and the image is prevented from being seen through to the front.

[0068] According to the third embodiment described above, even if the image projection system is configured to include a single type of projection device and screen, by switching between light for front projection and light for rear projection and projecting it from the projection device, both front projection and rear projection can be achieved, and the image can be prevented from showing through to the side opposite to the side on which it is projected.

[0069] In the third embodiment, the screen 10 is configured in the same manner as in the second embodiment. However, instead of this, the screen 10 may be configured in the same manner as in the first embodiment. In this case, the projection device 20 may be configured as shown in FIG. Figure 4 (a)~ Figure 42(c), and a control unit 28. In this case, as in the third embodiment, both front projection and rear projection can be realized by switching between light for front projection and light for rear projection from the projection device, and it is possible to prevent an image from being seen through to the side opposite to the side on which the image is projected.

[0070] [Terminology, transformations, etc.] The block diagrams used to explain the above embodiments show functional blocks. These functional blocks (components) are realized by any combination of at least one of hardware and software. The method of realizing each functional block is not particularly limited. That is, each functional block may be realized by using one device that is physically or logically combined, or may be realized by using two or more devices that are physically or logically separated and directly or indirectly connected (for example, by wire, wirelessly, etc.). The functional blocks may be realized by combining the one device or the multiple devices with software.

[0071] For example, the control unit 28 may function as a computer that performs the processing in the above embodiment. Fig. 10 is a diagram showing an example of a hardware configuration of the control unit 28. The above-mentioned control unit 28 may be physically configured as a computer device including a processor 1001, a memory 1002, a storage 1003, a communication device 1004, an input device 1005, an output device 1006, a bus 1007, etc.

[0072] In the following description, the term "apparatus" can be interpreted as a circuit, a device, a unit, etc. The hardware configuration of the control unit 28 may be configured to include one or more of the devices shown in the drawings, or may be configured to exclude some of the devices.

[0073] Each function in the control unit 28 is realized by loading a specific software (program) onto hardware such as a processor 1001 and a memory 1002, causing the processor 1001 to perform calculations, control communication by the communication device 1004, and control at least one of the reading and writing of data in the memory 1002 and the storage 1003.

[0074] Although the present disclosure has been described in detail above, it is clear to those skilled in the art that the present disclosure is not limited to the embodiments described in the present disclosure. The present disclosure can be implemented in modified and altered forms without departing from the spirit and scope of the present disclosure as defined by the claims. Therefore, the description of the present disclosure is intended to be illustrative and does not have any limiting meaning on the present disclosure.

[0075] The order of the steps, sequences, flow charts, etc. of each aspect / embodiment described in this disclosure may be changed unless inconsistent. For example, the methods described in this disclosure present elements of various steps using an example order, and are not limited to the particular order presented.

[0076] The input and output information may be stored in a specific location (e.g., memory) or may be managed using a management table. The input and output information may be overwritten, updated, or added to. The output information may be deleted. The input information may be transmitted to another device.

[0077] As used in this disclosure, the phrase "based on" does not mean "based only on," unless expressly stated otherwise. In other words, the phrase "based on" means both "based only on" and "based at least on."

[0078] When the terms "include," "including," and variations thereof are used in this disclosure, these terms are intended to be inclusive, similar to the term "comprising." Further, when used in this disclosure, the term "or" is not intended to be an exclusive or.

[0079] In this disclosure, where articles have been added due to translation, such as a, an, and the in English, the disclosure may include that the nouns following these articles are in the plural form.

[0080] In the present disclosure, the term "A and B are different" may mean "A and B are different from each other." The term may also mean "A and B are each different from C." Terms such as "separate" and "coupled" may also be interpreted in the same way as "different." [Explanation of symbols]

[0081] 1...image projection system, 10...screen, 11...patterned retarder layer, 11A...first part, 11B...second part, 12...polarizing layer, 12A...circularly polarizing layer, 13...reflective layer, 13A...reflective member, 13B...opaque member, 14...projection layer, 14A...quarter-wave plate, 14B...projection member, 20...projection device, 20A...first projection device, 20B...second projection device, 21...projector, 21A ...first projector, 21B...second projector, 22A...right circular polarizer, 22B...left circular polarizer, 23...vertical polarizer, 24A...quarter wave plate, 24B...quarter wave plate, 25...liquid crystal plate, 28...control unit, 29...image DB, 1001...processor, 1002...memory, 1003...storage, 1004...communication device, 1005...input device, 1006...output device, 1007...bus.

Claims

1. a screen for projecting an image from the projected light; a first projection device disposed on one side of the screen, that is, on the front side, and configured to emit vertically polarized light or horizontally polarized light, or right-handed circularly polarized light or left-handed circularly polarized light; and a second projection device disposed on the front side, which, when the light emitted by the first projection device is vertically polarized or horizontally polarized light, emits light polarized in a direction perpendicular to the vertically polarized light, and, when the light emitted by the first projection device is right-handed circularly polarized or left-handed circularly polarized light, emits circularly polarized light rotating in the opposite direction to the vertically polarized or horizontally polarized light; At least one of An image projection system comprising: The screen comprises: a first layer in which a first portion formed of a quarter-wave plate whose slow axis direction is a first direction perpendicular to the traveling direction of the projected light and a second portion formed of a quarter-wave plate whose slow axis direction is a second direction perpendicular to the traveling direction of the projected light and the first direction are alternately formed along a predetermined direction perpendicular to the traveling direction of the projected light; a second layer having a polarizing function of transmitting only one of a first polarized light beam emitted from the first portion and a second polarized light beam emitted from the second portion, for light beams having one type of polarization state that are incident on the first layer; a third layer in which a reflective portion that reflects but does not transmit light is formed at a position corresponding to one of the first portion or the second portion along a traveling direction of the projected light, and the reflective portion is not formed at a position corresponding to the other of the first portion or the second portion; and a fourth layer that transmits light incident from the front side to a rear side opposite to the front side but prevents the light from being reflected to the front side and emitted from the screen; The projected light is projected in a direction parallel to the upstream side of the projected light. Image projection system.

2. Both the first projection device and the second projection device, The image projection system according to claim 1 , comprising:

3. The fourth layer comprises: a layer that polarizes reflected light such that the reflected light reflected toward the front side is absorbed by the second layer; A layer that transmits light to the rear side; 3. The image projection system according to claim 1, further comprising:

4. The fourth layer comprises: a layer that transmits light to the rear side and is formed of a material that does not easily reflect light; 3. The image projection system according to claim 1, further comprising:

5. The first projection device is A configuration including a first projector that emits unpolarized light, and a right-handed circular polarization unit that converts the unpolarized light emitted from the first projector into right-handed circularly polarized light, Or, A configuration including a second projector that emits vertically polarized or horizontally polarized light, and a quarter-wave plate that converts the light emitted from the second projector into right-handed circularly polarized light; It is said that, The second projection device is A configuration including a first projector that emits unpolarized light, and a left-handed circular polarization unit that converts the unpolarized light emitted from the first projector into left-handed circularly polarized light, Or, A configuration including a second projector that emits vertically polarized or horizontally polarized light, and a quarter-wave plate that converts the light emitted from the second projector into left-handed circularly polarized light; It is said that, 5. An image projection system according to claim 1.

6. At least one of the right-handed circular polarization unit and the left-handed circular polarization unit is 6. The image projection system according to claim 5, further comprising a polarizing member that mechanically or electronically switches the polarization direction between vertical and horizontal, and a quarter-wave plate.

7. The first projection device is A configuration including a first projector that emits unpolarized light, and a vertical polarizing plate that converts the unpolarized light emitted from the first projector into vertically polarized light; Or, a third projector that emits vertically polarized light; It is said that, The second projection device is A configuration including a first projector that emits unpolarized light, and a horizontal polarizing plate that converts the unpolarized light emitted from the first projector into horizontally polarized light; Or, a fourth projector emitting horizontally polarized light; It is said that, 5. An image projection system according to claim 1.

8. A screen for projecting an image from projected light, a first layer in which a first portion formed of a quarter-wave plate whose slow axis direction is a first direction perpendicular to the traveling direction of the projected light and a second portion formed of a quarter-wave plate whose slow axis direction is a second direction perpendicular to the traveling direction of the projected light and the first direction are alternately formed along a predetermined direction perpendicular to the traveling direction of the projected light; a second layer having a polarizing function of transmitting only one of a first polarized light beam emitted from the first portion and a second polarized light beam emitted from the second portion, for light beams having one type of polarization state that are incident on the first layer; a third layer in which a reflective portion that reflects but does not transmit light is formed at a position corresponding to one of the first portion or the second portion along a traveling direction of the projected light, and the reflective portion is not formed at a position corresponding to the other of the first portion or the second portion; and a fourth layer that transmits light incident from a front side onto which the projected light is incident to a rear side opposite to the front side, but prevents the light from being reflected to the front side and emitted from the screen; The projected light is projected in a direction parallel to the upstream side of the projected light. screen.

Images