Image Projection System

Abstract

To enable a projection surface of a screen to be switched without deteriorating an image resolution with a simpler and cheaper configuration while preventing an image from being visible from a side opposite to a surface to be projected.SOLUTION: A screen 10 comprises: a transparent screen layer 12 for displaying an image with projected light; an optical element (wire grid layer 13) which is arranged on a surface on a downstream side of the screen layer 12 along a travel direction of the projected light, is applied with wire grids along a fixed direction, transmits light vibrating in a direction orthogonal to the fixed direction and reflects light vibrating in a direction in parallel to the fixed direction; and a low reflection layer 11 which is arranged on a surface on an upstream side of the screen layer 12 along the travel direction of the projected light and suppresses reflection of the light on the surface of the screen layer 12.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure provides: Image projection system for projecting an image 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 structural elements 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 portion of a 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 transparent glass screen product. [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] "Tracs: transparency-control for see-through displays," by David Lindlbauer et al., available at: https: / / dl.acm.org / doi / 10.1145 / 2642918.2647350 [Non-patent document 3] Product information: "Glascene (registered trademark) transparent glass screen," 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 surface such as window glass, there is a concern that the image may be unintentionally seen from the opposite side of the projection surface.

[0005] In relation to the above, there are also known techniques for projecting images onto both sides of a screen, rather than just one side, and although the technique for switching the projection surface of a screen during image projection can be realized by, for example, a configuration in which projectors are installed on both sides of the screen or a configuration in which displays are installed on both sides of the screen, a simpler and less expensive configuration is desired. On the other hand, it is also important not to reduce the resolution of the projected image.

[0006] Therefore, taking the above circumstances into consideration, the present disclosure aims to enable switching of the projection surface of a screen without reducing the resolution of the image, using a simpler and less expensive configuration, while avoiding the image from showing through to the opposite side of the surface to be projected. [Means for solving the problem]

[0007] The screen according to the present disclosure comprises: a transparent screen layer for displaying an image formed by projected light; an optical element arranged on the downstream surface of the screen layer along the direction of travel of the projected light, the optical element having a wire grid arranged along a fixed direction, transmitting light vibrating in a direction perpendicular to the fixed direction and reflecting light vibrating in a direction parallel to the fixed direction; and a low-reflection layer arranged on the upstream surface of the screen layer along the direction of travel of the projected light for suppressing reflection of light on the surface of the screen layer.

[0008] When the screen is irradiated with image light oscillating in a direction parallel to the fixed direction (the direction in which the wire grid is laid), the low-reflection layer arranged on the upstream surface of the screen layer in the light propagation direction suppresses reflection of the light on the surface of the screen layer, and the image light reaches the optical element arranged on the downstream surface of the screen layer in the light propagation direction. Here, the optical element reflects the image light oscillating in a direction parallel to the fixed direction (the direction in which the wire grid is laid), without transmitting it, and an image based on the reflected image light is projected forward.

[0009] On the other hand, when the screen is irradiated with image light oscillating in a direction perpendicular to the fixed direction (the direction in which the wire grid is laid), the low-reflection layer suppresses reflection of the light on the surface of the screen layer, and the image light reaches the optical element arranged on the downstream surface of the screen layer in the light traveling direction. Here, the optical element transmits the image light oscillating in a direction perpendicular to the fixed direction (the direction in which the wire grid is laid) without reflecting it, and an image based on the transmitted image light is rear-projected.

[0010] Furthermore, in both the front projection and rear projection, the image is projected using the entire surface of the screen, so that a decrease in image resolution can be suppressed.

[0011] As described above, the screen according to the present disclosure makes it possible to switch the projection surface of the screen without reducing the resolution of the image, while avoiding the image from showing through to the surface opposite to the surface to be projected, with a simpler and less expensive configuration. [Effects of the Invention]

[0012] According to the present disclosure, it is possible to switch the projection surface of a screen without reducing the resolution of the image, using a simpler and less expensive configuration, while avoiding the image from showing through to the opposite side of the surface to be projected. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1(a) is a diagram illustrating the configuration and operation of an image projection system in the first embodiment, and FIG. 1(b) is a diagram illustrating the function of a wire grid polarizer. [Figure 2] FIG. 4 is a flowchart showing the operation of a control unit in the first embodiment. [Figure 3] (a) is a diagram showing an example of projecting characters in different languages onto the front and back surfaces, (b) is a diagram showing an example of the same object projected onto the front as seen from the front and onto the back as seen from the back, and (c) is a diagram showing the projected images when an LCD shutter covering part of the screen is off and on. [Figure 4] FIG. 10(a) is a diagram illustrating the configuration of an image projection system according to a second embodiment and its operation during front projection, and FIG. 10(b) is a diagram illustrating its operation during rear projection. [Figure 5] FIG. 10 is a flowchart showing the operation of a control unit in the second embodiment. [Figure 6] 10A and 10B are diagrams for explaining the configuration and operation of an image projection system according to a third embodiment. [Figure 7] FIG. 11 is a flowchart showing the operation of a control unit in the third embodiment. [Figure 8] 10A and 10B are diagrams for explaining the configuration and operation of an image projection system according to a fourth embodiment. [Figure 9] FIG. 10(a) is a flowchart showing control based on image brightness in the fourth embodiment, and FIG. 10(b) is a flowchart showing control based on brightness around the screen. [Figure 10] 10A and 10B are diagrams for explaining the configuration and operation of an image projection system according to a fifth embodiment. [Figure 11] FIG. 13 is a flowchart showing the operation of a control unit in the fifth embodiment. [Figure 12] FIG. 2 is a diagram illustrating an example of a hardware configuration of a control unit. DETAILED DESCRIPTION OF THE INVENTION

[0014] Various embodiments of a screen and an image projection system according to the present disclosure will be described below with reference to the drawings. Five embodiments will be described below, but an overview of these embodiments will be provided first.

[0015] The first embodiment relates to an image projection system including a screen and a projection device including a first projection unit that projects S-polarized light for front projection and a second projection unit that projects P-polarized light for rear projection. The second embodiment relates to an image projection system including a screen and a projection device including a single projection unit and a liquid crystal element that S-polarizes or P-polarizes image light. The third embodiment relates to an image projection system including a configuration that controls the transparency of an LCD shutter (light-blocking member) near the screen based on image data of an object approaching the screen, added to the configuration of the first embodiment. The fourth embodiment relates to an image projection system including a configuration that adjusts the intensity of image light based on the brightness of the image or the brightness around the screen, added to the configuration of the first embodiment. The fifth embodiment relates to an image projection system including a configuration that removes ghost images that are projected on the opposite side of the screen.

[0016] [First embodiment] As shown in FIG. 1(a), 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.

[0017] The screen 10 is composed of three layers: a low-reflection layer 11, a screen layer 12, and a wire grid layer 13. The above three layers are arranged in the following order from the light-receiving surface side of the projected light (the left side in Figure 1(a)) along the thickness direction (the left-right direction in Figure 1(a)): low-reflection layer 11, screen layer 12, wire grid layer 13.

[0018] Of these, the screen layer 12 is a transparent layer that reflects an image formed by projected light. The low-reflection layer 11 is a layer made of a low-reflection material that suppresses reflection of light on the surface of the screen layer 12. The wire-grid layer 13 is a layer on which a wire grid is applied along a certain direction. In the present embodiment, as an example, the wire grid is applied along a direction that reflects S-polarized light emitted from a first projection device 20A (described later) (the vertical direction in FIG. 1(a)). Therefore, as shown in FIG. 1(b), the wire-grid layer 13 reflects S-polarized light and transmits P-polarized light emitted from a second projection device 20B (described later). Note that while the low-reflection layer 11 and the wire-grid layer 13 are illustrated as layers in FIG. 1(a), the low-reflection layer 11 and the wire-grid layer 13 may be configured as thin layers attached to the surface of the screen layer 12.

[0019] The projection device 20 is arranged on one side (hereinafter referred to as the "front side") of the screen 10 and includes a first projection device 20A that emits S-polarized light, and a second projection device 20B that is also arranged on the front side and emits P-polarized light. The first projection device 20A includes a first projector 21A that emits unpolarized light and a first polarizing element 22A that absorbs the horizontal component of the light emitted from the first projector 21A. Since the horizontal component of the light is absorbed by the first polarizing element 22A, S-polarized light is emitted from the first projection device 20A. In other words, the first polarizing element 22A polarizes the light emitted from the first projector 21A into light that vibrates in a direction parallel to the wire-grid arrangement direction of the wire-grid layer 13 described above. On the other hand, the second projection device 20B includes a second projector 21B that emits unpolarized light and a second polarizing element 22B that absorbs the vertical component of the light emitted from the second projector 21B, and since the vertical component of the light is absorbed by the second polarizing element 22B, P-polarized light is emitted from the second projection device 20B. That is, the second polarizing element 22B polarizes the light emitted from the second projector 21B into light that vibrates in a direction perpendicular to the direction in which the wire grids are laid out in the wire-grid layer 13. Note that the first projection device 20A and the second projection device 20B are not limited to being composed of one each, and may each be composed of multiple devices.

[0020] The projection device 20 further includes a control unit 28 that supplies image data of the image to be projected to the first projector 21A and the second projector 21B, and the control unit 28 has a built-in image DB 29 that stores the image data. The control unit 28 is assumed to previously store information regarding the image projection process to be performed (information indicating front projection, rear projection, double-sided projection of the same image, or double-sided projection of different images), and determines the image projection process to be performed based on this information. In each of the first projection device 20A and the second projection device 20B described above, the projector and the polarizing element do not necessarily have to be in contact with each other, and may be separated by a predetermined distance.

[0021] Next, the processing operation of the image projection system 1 of the first embodiment will be described. First, the control unit 28 determines whether the image projection process 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 determines whether the image projection process to be executed is single-sided projection or not (double-sided projection) in step S1 shown in FIG. 2, and if YES, determines in step S2 whether the process is single-sided projection, front projection or not (rear projection). On the other hand, if NO (double-sided projection) in step S1, determines in step S3 whether the process projects the same image or not (projects different images).

[0022] If the image projection process to be executed is front projection, the results of steps S1 and S2 in FIG. 2 are YES, and the process proceeds to step S4, where control unit 28 supplies image data to be front-projected to first projector 21A. As a result, as shown by the solid lines in FIG. 1, unpolarized light representing the image to be front-projected is emitted from first projector 21A, the horizontal component of the light is absorbed by first polarizing element 22A, and S-polarized image light is emitted from first projection device 20A and reaches screen 10. At this time, low-reflection layer 11 suppresses light reflection on the surface of screen layer 12, and the S-polarized image light reaches wire-grid layer 13. Here, wire-grid layer 13 reflects the S-polarized image light without transmitting it, as shown in FIG. 1(b), and an image based on the reflected image light is front-projected.

[0023] If the image projection process to be executed is rear projection, the result in step S1 of FIG. 2 is YES and the result in step S2 is NO, 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 vertical component of the light is absorbed by second polarizing element 22B, and P-polarized image light is emitted from second projection device 20B and reaches screen 10. At this time, low-reflection layer 11 suppresses light reflection on the surface of screen layer 12, and the P-polarized image light reaches wire-grid layer 13. Here, wire-grid layer 13 transmits the P-polarized image light without reflecting it, as shown in FIG. 1(b), and an image based on the transmitted image light is rear-projected.

[0024] 2, if the image projection process to be performed is for double-sided projection of different images, the results of steps S1 and S3 in FIG. 2 are NO, and the process proceeds to step S7, where control unit 28 supplies image data to be front-projected to first projector 21A and image data to be rear-projected to second projector 21B. As a result, as shown by the solid lines in FIG. 1, unpolarized light representing the image to be front-projected is emitted from first projector 21A, the horizontal component of the light is absorbed by first polarizing element 22A, and S-polarized image light is emitted from first projection device 20A and reaches screen 10. At the same time, unpolarized light representing the image to be rear-projected is emitted from second projector 21B, the vertical component of the light is absorbed by second polarizing element 22B, and P-polarized image light is emitted from second projection device 20B and reaches screen 10. Thereafter, the operation relating to step S4 and the operation relating to step S5 are both executed simultaneously, and as a result, both front projection and rear projection (that is, double-sided projection) are realized.

[0025] 2, if the image projection process to be executed is double-sided projection of the same image, the result is NO in step S1 and YES in step S3, and the process proceeds to step S6, where control unit 28 supplies image data to be front-projected to first projector 21A and image data of a mirror image of the image to be front-projected to second projector 21B. As a result, unpolarized light representing the image to be front-projected is emitted from first projector 21A, the horizontal component of the light is absorbed by first polarizing element 22A, and S-polarized image light is emitted from first projection device 20A and reaches screen 10. At the same time, unpolarized light representing the mirror image of the image to be front-projected is emitted from second projector 21B, the vertical component of the light is absorbed by second polarizing element 22B, and P-polarized image light is emitted from second projection device 20B and reaches screen 10. Thereafter, the operations according to step S4 and step S5 are both executed simultaneously, resulting in both front and rear projection (i.e., double-sided projection). At this time, a mirror image of the image to be front-projected is projected onto the rear, and the image seen from the rear is the same as the image to be front-projected, thereby achieving double-sided projection of the same image. Furthermore, in both the front and rear projection described above, it is possible to prevent the image from showing through to the opposite side of the surface to be projected, and by projecting the image using the entire surface of the screen, it is possible to suppress a decrease in image resolution.

[0026] According to the first embodiment described above, it is possible to switch the projection surface of the screen without reducing the image resolution, using a simpler and less expensive configuration, while preventing the image from showing through to the surface opposite the surface to be projected. Specifically, 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."

[0027] As a result, for example, in the case of double-sided projection of images with different image projection processes to be executed, the English characters "Hello" can be projected in front while the Japanese characters "Hello" can be projected in rear, as shown in Fig. 3(a). Also, as shown in Fig. 3(b), an image of a cow doll seen from the front can be projected in front while an image of the same cow doll seen from the back can be projected in rear.

[0028] [Second embodiment] In the second embodiment, an embodiment will be described relating to an image projection system including a screen and a projection device including a single projection unit and a liquid crystal element that S-polarizes or P-polarizes image light.

[0029] 4(a) and 4(b), the image projection system 1 in the second embodiment includes a screen 10 for displaying a projected image, and a single projection device 20 provided on one side of the screen 10. The configuration of the screen 10 is the same as that in the first embodiment described above, so a duplicated description will be omitted.

[0030] The projection device 20 is arranged on one side (front side) of the screen 10 and includes a third projector 21 that emits light of the image to be projected, a liquid crystal element 23 that polarizes the light emitted from the third projector 21 into S-polarized light or P-polarized light, and a control unit 28.

[0031] In addition to the functions described in the first embodiment, control unit 28 has a function of controlling the polarization operation, described later, of liquid crystal element 23. Control unit 28 also stores information regarding the image projection process to be executed (information indicating either front projection or rear projection) in advance, and determines the image projection process to be executed based on this information. Furthermore, third projector 21 and liquid crystal element 23 described above do not necessarily need to be in contact with each other, and may be separated by a predetermined distance.

[0032] Next, the processing operation in the image projection system 1 of the second embodiment will be described. First, the control unit 28 determines whether the image projection process to be executed is "front projection" or "rear projection," and supplies image data according to the determination result. For example, the control unit 28 determines whether the image projection process to be executed is front projection or not (rear projection) in step S11 shown in FIG. 5.

[0033] If the answer is YES in step S11, control unit 28 switches liquid crystal element 23 to horizontal polarization and supplies image data to be front-projected to third projector 21 (step S12). As a result, unpolarized light representing an image to be front-projected is emitted from third projector 21, and the horizontal component of the light is absorbed by liquid crystal element 23 after the switching, and S-polarized image light reaches screen 10. At this time, low-reflection layer 11 suppresses reflection of light on the surface of screen layer 12, and the S-polarized image light reaches wire-grid layer 13. Here, wire-grid layer 13 reflects the S-polarized image light without transmitting it, as shown in FIG. 1(b), and an image based on the reflected image light is front-projected.

[0034] 5, the control unit 28 switches the liquid crystal element 23 to vertical polarization and supplies the image data to be rear-projected to the third projector 21 (step S13). As a result, unpolarized light representing the image to be rear-projected is emitted from the third projector 21, and the vertical component of the light is absorbed by the switched liquid crystal element 23, resulting in P-polarized image light reaching the screen 10. At this time, the low-reflection layer 11 suppresses reflection of light on the surface of the screen layer 12, and the P-polarized image light reaches the wire-grid layer 13. Here, the wire-grid layer 13 transmits the P-polarized image light without reflecting it, as shown in FIG. 1(b), and an image based on the transmitted image light is rear-projected.

[0035] According to the second embodiment described above, in the image projection system 1 having a simple and inexpensive configuration equipped with the screen 10 and a single projection device 20, it is possible to achieve either front projection or rear projection without reducing the image resolution while preventing the image from showing through to the surface opposite to the surface to be projected. In addition, by using the control unit 28 to quickly switch the polarization function (horizontal polarization, vertical polarization) of the liquid crystal element 23, it is also possible to simultaneously perform both front projection and rear projection.

[0036] In the second embodiment, an example has been described in which the control unit 28 controls the polarization operation of the liquid crystal element 23 depending on whether the projection is front or rear, but such control by the control unit 28 is not essential, and the liquid crystal element 23 may be configured to perform either front projection or rear projection by fixing it to a configuration that performs either horizontal polarization or vertical polarization.

[0037] [Third embodiment] In the third embodiment, an embodiment will be described in which a configuration for controlling the transparency of a light blocking member near the screen based on image data of an object approaching the screen is added to the configuration of the first embodiment.

[0038] As shown in FIG. 6, the image projection system 1 of the third embodiment further includes an LCD (Liquid Crystal Display) shutter 32 as an example of a light-blocking member provided near the screen 10, and a first image sensor 31 that acquires image data of an object approaching the screen 10. The control unit in the third embodiment is configured by a first control unit 28A that controls the operation of the LCD shutter 32 (FIG. 7) in addition to controlling the image projection process (FIG. 2). The LCD shutter 32 is a liquid crystal shutter that utilizes the property of liquid crystals that their light transmittance changes when the applied voltage is changed, and the transparency can be controlled by controlling the voltage. The other components shown in FIG. 6 are the same as those of the first embodiment, so repeated explanations will be omitted.

[0039] Next, a process specific to the third embodiment will be described using the flow diagram of FIG. 7. First, the first control unit 28A acquires image data from the first image sensor 31 (step S21), and determines whether a person approaching the screen 10 is captured in the image based on the image data using existing face recognition technology or the like (step S22). If a person approaching the screen 10 is captured, the LCD shutter 32 controls the voltage applied to a portion of the LCD shutter 32 corresponding to the line of sight of the person, thereby reducing the transparency of the corresponding portion, thereby preventing the person approaching the screen 10 from seeing the image captured on the screen 10 (step S23). The process of FIG. 7 may be executed periodically, for example, at predetermined time intervals or based on a predetermined schedule, or may be executed on demand in response to a start instruction from an operator of the first control unit 28A.

[0040] The control in the third embodiment described above makes it possible to detect a person approaching the screen 10 and prevent the image displayed on the screen 10 from being seen by that person.

[0041] 7, other objects such as a drone equipped with a camera or an animal may be detected in addition to a person approaching the screen 10. For example, FIG. 3(c) shows an example in which a rabbit approaching the screen 10 is detected and control is performed to reduce the transparency of only the portion corresponding to the gaze direction of the rabbit. Furthermore, the control is not limited to reducing the transparency of only the portion corresponding to the gaze direction of the approaching person as in step S22, and control may be performed to reduce the transparency of the entire LCD shutter 32.

[0042] Furthermore, in the third embodiment, an example was described in which a configuration for controlling the transparency of a light-blocking member near the screen based on image data of an object approaching the screen was added to the configuration of the first embodiment, but a configuration for controlling the transparency of a light-blocking member in the same manner as above may also be added to the configuration of the second embodiment (a configuration having a single projection device), and similar effects can be achieved.

[0043] [Fourth embodiment] In the fourth embodiment, an embodiment will be described in which a configuration for adjusting the intensity of image light based on the brightness of the image or the brightness around the screen is added to the configuration of the first embodiment.

[0044] As shown in FIG. 8 , the image projection system 1 of the fourth embodiment further includes an illuminance sensor 33 that detects the brightness of an image projected on the front or rear surface of the screen 10 or the brightness of the periphery of the screen 10. The control unit of the fourth embodiment is configured with a second control unit 28B that not only controls the image projection process ( FIG. 2 ) but also controls the intensity of the projection light based on the detected brightness ( FIGS. 9( a) and 9(b) ). If the image projected on the screen 10 is too bright, unwanted images caused by the image light become noticeable. Therefore, the second control unit 28B predetermines and stores a reference value for the brightness of the image at which adjustment of the intensity of the projection light should be initiated as a “first reference.” Furthermore, if the periphery of the screen is too dark, unwanted images caused by the image light become noticeable. Therefore, the second control unit 28B predetermines and stores a reference value for the brightness of the periphery of the screen at which adjustment of the intensity of the projection light should be initiated as a “second reference.” Note that the other configurations shown in FIG. 8 are the same as those of the first embodiment, and therefore redundant description will be omitted.

[0045] Next, a process unique to the fourth embodiment will be described using the flow charts of FIGS. 9(a) and 9(b). When a sensor for detecting the brightness of an image projected on the front or rear surface of the screen 10 is used as the illuminance sensor 33, the process shown in FIG. 9(a) is executed. The second control unit 28B acquires data on the brightness of the image from the illuminance sensor 33 (step S31) and determines whether the brightness of the image is equal to or greater than a pre-stored first reference value (step S32). If the brightness of the image is equal to or greater than the first reference value, it is determined that adjustment of the intensity of the projection light should be initiated. Therefore, the second control unit 28B adjusts the intensity of the projected light to be lower (step S33). This control according to the fourth embodiment quickly detects a situation in which the image projected on the screen 10 is too bright, causing an unwanted image to stand out, and adjusts the intensity of the image light to be lower, thereby preventing the unwanted image from standing out.

[0046] Furthermore, when a sensor that detects the brightness around the screen is used as the illuminance sensor 33, the process shown in FIG. 9(b) is executed. The second control unit 28B acquires data on the brightness around the screen from the illuminance sensor 33 (step S34) and determines whether the brightness around the screen is equal to or less than a pre-stored second standard (step S35). If the brightness around the screen is equal to or less than the second standard, it is determined that adjustment of the intensity of the projection light should be started. Therefore, the second control unit 28B adjusts the intensity of the projected light to be lower (step S36). This control according to the fourth embodiment quickly detects a situation in which the periphery of the screen is too dark and an unwanted image becomes noticeable, and adjusts the intensity of the image light to be lower, thereby preventing the unwanted image from becoming noticeable. The processes shown in FIGS. 9(a) and 9(b) may be executed periodically, for example, at predetermined time intervals or based on a predetermined schedule, or may be executed on demand in response to a start instruction from an operator of the second control unit 28B.

[0047] In the fourth embodiment, an example was described in which a configuration for adjusting the intensity of image light based on the brightness of the image or the brightness around the screen was added to the configuration of the first embodiment, but a configuration for adjusting the intensity of image light in the same manner as above may also be added to the configuration of the second embodiment (a configuration having a single projection device), and similar effects can be achieved.

[0048] [Fifth embodiment] In the fifth embodiment, an embodiment will be described in which a configuration for removing ghost images that are projected on the opposite side of the screen surface is added to the configuration of the first embodiment.

[0049] 10, the image projection system 1 in the fifth embodiment further includes a second image sensor 34 disposed downstream of the screen 10 along the traveling direction of the projection light and configured to acquire image data of a rear ghost image that would otherwise be projected on the rear surface of the screen 10 during front or double-sided projection, and a third image sensor 35 disposed upstream of the screen 10 along the traveling direction of the projection light and configured to acquire image data of a front ghost image that would otherwise be projected on the front surface of the screen 10 during rear or double-sided projection. The control unit in the fifth embodiment further includes a third control unit 28C that, in addition to controlling the image projection process (FIG. 2), controls the second projection device 20B to emit image light for projecting an image that grays out the rear ghost image onto the rear surface of the screen based on the image data of the rear ghost image acquired by the second image sensor 34, and controls the first projection device 20A to emit image light for projecting an image that grays out the front ghost image onto the front surface of the screen based on the image data of the front ghost image acquired by the third image sensor 35 (FIG. 11). That is, during front projection, a rear ghost image may be displayed, during rear projection, a front ghost image may be displayed, and during double-sided projection, both a front ghost image and a rear ghost image or both may be displayed. The third control unit 28C has a function to remove the ghost image that is actually displayed. Note that the other configurations shown in Fig. 10 are the same as those in the first embodiment, so redundant explanations will be omitted.

[0050] Next, a process specific to the fifth embodiment will be described using the flow chart of FIG. 11. First, the third control unit 28C acquires image data of a ghost image from the second image sensor 34 and the third image sensor 35 (step S41) and causes the third control unit 28C to emit image light for projecting an image that grays out the ghost image onto the screen 10 (step S42). Specifically, during front projection or double-sided projection, the third control unit 28C acquires image data of a rear ghost image from the second image sensor 34 and causes the second projection device 20B to emit image light for projecting an image that grays out the rear ghost image onto the rear of the screen based on the acquired image data of the rear ghost image. Furthermore, during rear projection or double-sided projection, the third control unit 28C acquires image data of a front ghost image from the third image sensor 35 and causes the first projection device 20A to emit image light for projecting an image that grays out the front ghost image onto the front of the screen based on the acquired image data of the front ghost image. With regard to the image to be grayed out, in step S42, for example, the image to be grayed out is obtained so that the sum of the RGB values of the ghost image obtained from the image data and the RGB values of the image to be grayed out is RGB(255,255,255), and image light is emitted to project the image onto the screen 10. In this case, the ghost image changes to a white image of RGB(255,255,255), making it less noticeable. Note that the process of FIG. 11 may be executed periodically, for example, at predetermined time intervals or based on a predetermined schedule, or may be executed on demand in response to a start instruction from the operator of the third control unit 28C.

[0051] Generally, when comparing rear projection with front projection, a ghost image (front ghost image) tends to appear more strongly during rear projection, but the control in the fifth embodiment described above can make the front ghost image, which may appear more strongly during rear projection or double-sided projection, less noticeable and eliminate it. Furthermore, the rear ghost image, which may appear during front projection or double-sided projection, can also be made less noticeable and eliminate it.

[0052] [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. Furthermore, the method for realizing each functional block is not particularly limited. That is, each functional block may be realized using a single device that is physically or logically coupled, or may be realized using two or more physically or logically separated devices that are directly or indirectly connected (for example, using wires, wirelessly, etc.) and these multiple devices. The functional block may also be realized by combining the single device or multiple devices with software.

[0053] For example, the control unit 28 may function as a computer that performs the processing in the above-described embodiment. Fig. 12 is a diagram showing an example of the hardware configuration of the control unit 28. The above-described 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.

[0054] 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 apparatuses shown in the drawings, or may be configured to exclude some of the apparatuses.

[0055] Each function of control unit 28 is realized by loading predetermined software (programs) onto hardware such as processor 1001 and memory 1002, causing processor 1001 to perform calculations, control communication by communication device 1004, and control at least one of reading and writing of data from memory 1002 and storage 1003. Note that first control unit 28A, second control unit 28B, and third control unit 28C also have the same configuration as that of control unit 28 described above.

[0056] 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 herein. 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.

[0057] The order of the procedures, sequences, flowcharts, etc. of each aspect / embodiment described in this disclosure may be changed unless it is consistent. 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.

[0058] Input and output information may be stored in a specific location (for example, memory) or may be managed using a management table. Input and output information may be overwritten, updated, or added to. Output information may be deleted. Input information may be sent to another device.

[0059] 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."

[0060] When used in this disclosure, the terms "include," "including," and variations thereof are intended to be inclusive, similar to the term "comprising." Furthermore, when used in this disclosure, the term "or" is not intended to be an exclusive or.

[0061] In this disclosure, where articles are added by translation, such as a, an, and the in English, the disclosure may include that the nouns following these articles are in the plural form.

[0062] 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]

[0063] 1...image projection system, 10...screen, 11...low-reflection layer, 12...screen layer, 13...wire grid layer, 20...projection device, 20A...first projection device, 20B...second projection device, 21A...first projector, 21B...second projector, 21...third projector, 22A...first polarizing element, 22B...second polarizing element, 23...liquid crystal element, 28...control unit, 28A...first control unit, 28B...second control unit, 28C...third control unit, 29...image DB, 31...first image sensor, 32...LCD shutter, 33...illuminance sensor, 34...second image sensor, 35...third image sensor, 1001...processor, 1002...memory, 1003...storage, 1004...communication device, 1005...input device, 1006...output device, 1007...bus.

Claims

1. A transparent screen layer for projecting an image from projected light; an optical element arranged on a downstream surface of the screen layer along the traveling direction of the projected light, the optical element having a wire grid formed along a certain direction, transmitting light oscillating in a direction perpendicular to the certain direction and reflecting light oscillating in a direction parallel to the certain direction; a low-reflection layer disposed on an upstream surface of the screen layer along the direction of travel of the projected light, the low-reflection layer suppressing reflection of light on the surface of the screen layer; a screen comprising: The screen is disposed on the front side, which is the incident side of the projected light, a first projector that emits the light to be projected; and a first polarizing element that polarizes the light emitted from the first projector into light that vibrates in a direction parallel to the certain direction; a first projection device including: Located on the front side, a second projector that emits the projected light; and a second polarizing element that polarizes the light emitted from the second projector into light that vibrates in a direction perpendicular to the certain direction; a second projection device including: a light-blocking member having variable transparency, the light-blocking member being disposed downstream of the screen along the direction of travel of the projected light; a first control unit that controls the transparency of the light blocking member; a first image sensor for acquiring image data of an object approaching the screen; Equipped with The first control unit When the image data acquired by the first image sensor is image data representing a person approaching the screen, the transparency of the portion of the light blocking member corresponding to the line of sight of the person is reduced so that the image projected on the screen cannot be seen. Image projection system.

2. A transparent screen layer for projecting an image from projected light; an optical element arranged on a downstream surface of the screen layer along the traveling direction of the projected light, the optical element having a wire grid formed along a certain direction, transmitting light oscillating in a direction perpendicular to the certain direction and reflecting light oscillating in a direction parallel to the certain direction; a low-reflection layer disposed on an upstream surface of the screen layer along the direction of travel of the projected light, the low-reflection layer suppressing reflection of light on the surface of the screen layer; a screen comprising: The screen is disposed on the front side, which is the incident side of the projected light, a third projector that emits the projected light; and a liquid crystal element that polarizes the light emitted from the third projector into light that vibrates in a direction parallel to the certain direction or light that vibrates in a direction perpendicular to the certain direction; a third projection device including: a light-blocking member having variable transparency, the light-blocking member being disposed downstream of the screen along the direction of travel of the projected light; a first control unit that controls the transparency of the light blocking member; a first image sensor for acquiring image data of an object approaching the screen; Equipped with The first control unit When the image data acquired by the first image sensor is image data representing a person approaching the screen, the transparency of the portion of the light blocking member corresponding to the line of sight of the person is reduced so that the image projected on the screen cannot be seen. Image projection system.

Images