WO2017181728A1 - 一种背投系统及屏幕 - Google Patents

一种背投系统及屏幕 Download PDF

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Publication number
WO2017181728A1
WO2017181728A1 PCT/CN2016/113976 CN2016113976W WO2017181728A1 WO 2017181728 A1 WO2017181728 A1 WO 2017181728A1 CN 2016113976 W CN2016113976 W CN 2016113976W WO 2017181728 A1 WO2017181728 A1 WO 2017181728A1
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WIPO (PCT)
Prior art keywords
visible light
light
scattering
red
green
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PCT/CN2016/113976
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English (en)
French (fr)
Inventor
罗伯森布莱恩
李昆
初大平
姚峻
Original Assignee
华为技术有限公司
剑桥实业有限公司
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Application filed by 华为技术有限公司, 剑桥实业有限公司 filed Critical 华为技术有限公司
Publication of WO2017181728A1 publication Critical patent/WO2017181728A1/zh

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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
    • G03B21/00—Projectors or projection-type viewers; Accessories therefor
    • G03B21/54—Accessories
    • G03B21/56—Projection screens
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
    • G03B21/00—Projectors or projection-type viewers; Accessories therefor
    • G03B21/14—Details
    • G03B21/26—Projecting separately subsidiary matter simultaneously with main image
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N9/00—Details of colour television systems
    • H04N9/12—Picture reproducers
    • H04N9/31—Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM]
    • H04N9/3141—Constructional details thereof

Definitions

  • the present invention relates to the field of projection technology, and in particular, to a rear projection system and a screen.
  • the projection system can be divided into a front projection system and a rear projection system.
  • the projection system in which the projector is disposed behind the projection screen is called a rear projection system, also called a rear projection system.
  • the projection device can be hidden behind the projection screen, and the user does not need to see the projection device during the process of viewing the projection, which is better for the user, so the rear projection system has been widely used in various scenarios, such as remote video conference. Scenes or home entertainment scenes, and more.
  • the device that collects the depth information is called a deep acquisition device.
  • the depth acquisition device generally includes an infrared emitter and an infrared camera.
  • the infrared emitter emits invisible light, such as infrared light.
  • the infrared light forms a diffuse reflection on the surface of the speaker, and then the reflected infrared light is obtained through the infrared camera, and the reflected infrared light is returned. Light can get in-depth information about the speaker.
  • the depth acquisition device can be disposed behind the projection screen, and the projection screen is set to be transparent, so that the infrared light projected by the depth acquisition device can be projected onto the object in front of the projection screen through the projection screen to achieve depth.
  • the collection of information also allows the user located in front of the projection screen to see objects behind the projection screen, such as projection equipment, depth acquisition equipment and other objects, in addition to the projected image, thereby interfering with the viewing effect of the projected image.
  • the light source of the projection device (such as a light bulb) may also be punctured to The user's eyes affect the user's viewing experience with the projected image.
  • the embodiment of the invention provides a rear projection system and a screen for enhancing the viewing experience of the user while realizing the depth information collection.
  • a rear projection system in a first aspect, includes a projection screen, a projection device, and a depth acquisition device.
  • the projection screen includes a scattering layer for presenting an image
  • the projection device is for projecting visible light to the projection screen to cause the projection screen to present an image
  • the depth acquisition device is located on the same side of the projection screen as the projection device for positioning through the projection screen
  • An object on the other side of the projection screen projects invisible light, and receives reflected light of the object that reflects the invisible light, thereby obtaining depth information of the object
  • the scattering layer is used to view visible light from one side of the projection screen Visible light is Rayleigh scattering, and the scattering of visible light by the scattering layer is light to the scattering intensity of the scattering layer to invisible light, so that the user on the other side of the projection screen can not see the object located on one side of the projection screen, and Enables the depth acquisition device to obtain depth information of the object.
  • the wavelength of the invisible light is greater than the wavelength of the visible light.
  • the visible light includes three primary colors, that is, includes blue additivity, green visible light, and red visible light
  • the invisible light includes infrared light or far infrared light.
  • one side of the projection screen can be regarded as being located behind the projection screen, that is, the projection device and the depth acquisition device are located behind the projection screen, and the scattering effect of the scattering layer in the projection screen can be used.
  • the depth acquisition device located behind the projection screen accurately collects the object located in front of the projection screen, and also ensures the normal projection of the projection device behind the projection screen to meet the projection requirements of the user, and also because the projection screen can also Blocking objects behind it, making it impossible to see objects behind the projection screen, such as projection devices and depth acquisition devices behind the projection screen, so that they can be in the space behind the projection screen Place other objects to improve space utilization, and when the projection screen is large enough, it is equivalent to placing a curtain wall in front of the user.
  • the light source included in the projection device or some indicators on the depth acquisition device cannot project the image to the user. Watching caused interference And the influence, in turn, can improve the user's viewing experience. At the same time, since the depth acquisition device is placed behind the projection screen, the appearance of the front side of the projection screen can be ensured as much as possible, and the projection system is clean and tidy.
  • the depth acquisition device can be disposed at any position within the space behind the projection screen, based on its position adjustable, the acquisition range of the depth acquisition device can be dynamically adjusted by changing the position of the depth acquisition device to ensure It can collect the depth information of the image in front of the projection screen as completely as possible to improve the accuracy of depth information collection.
  • the image formed by the projection device on the projection screen is visible, but the object behind the projection screen is not visible.
  • This phenomenon can be first seen with reference to the object behind the rear projection TV screen but the rear projection TV. It can be imaged, or when the object is close to the frosted glass, the outline of the object can be seen through the frosted glass.
  • the specific principle may be that when the object on the other side of the projection screen is far from the projection screen, the surface of the object is reflected. Visible light (the object is equivalent to the light source) is scattered after a certain length of propagation, and it is difficult for the human eye to determine the position of the light source according to the reverse propagation direction of the scattered visible light, but the projection device can focus the light on the projection screen.
  • the scattering layer comprises scattering particles having a diameter within a range of Rayleigh scattering diameters.
  • the Rayleigh scattering diameter range is such that the scattering particles scatter the visible light and the invisible light by Rayleigh scattering.
  • the scattering intensity of the Rayleigh scattering is inversely proportional to the fourth power of the wavelength of the incident light
  • the wavelength of invisible light is greater than the wavelength of visible light, but in various categories
  • the scattering characteristics of Rayleigh scattering determine that the scattering intensity decreases with increasing wavelength, and the scattering intensity is inversely proportional to the fourth power of the wavelength of the incident light, indicating that the scattering intensity varies with wavelength.
  • the increased reduction is relatively large, which is also in line with the requirements for the scattering layer in the embodiment of the present invention. Therefore, the embodiment of the present invention utilizes the characteristics of Rayleigh scattering to satisfy the scattering layer's requirements for the scattering intensity of visible light and invisible light. That is, the scattering layer in the embodiment of the invention has scattering characteristics of Rayleigh scattering.
  • the visible light projected by the projection device includes blue visible light and red visible light; and the scattering layer further includes a diameter Red light resonance particles in the red light balance diameter range; wherein the red light resonance particles generate a plasmon resonance effect under red visible light to enhance the scattering intensity of the red visible light, so that the scattering intensity of the scattering layer to the red visible light and the scattering layer are blue
  • the difference between the scattering intensities of the visible light is less than the preset red light balance scattering intensity.
  • the scattering intensity when Rayleigh scattering is performed is the largest, so the red light balance can be adopted by using the scattering intensity of the blue visible light as a reference.
  • the red-light resonance particles in the diameter range enhance the scattering intensity of red visible light to minimize the difference in scattering intensity between red visible light and blue visible light, and reduce the difference in projection display by reducing the difference in scattering, thereby improving the projection quality.
  • the visible light projected by the projection device includes blue visible light and green visible light; and the scattering layer further includes a diameter Green light resonance particles in the green light balance diameter range; wherein the green light resonance particles generate a plasmon resonance effect under green visible light to enhance the scattering intensity to the green visible light, so that the scattering intensity of the scattering layer to the green visible light and the scattering layer to the blue The difference between the scattering intensities of the visible light is less than the preset green light balance scattering intensity.
  • the scattering intensity when performing the Rayleigh scattering is the largest, so the green light balance can be adopted by using the scattering intensity of the blue visible light as a reference.
  • Green-light resonant particles in the diameter range to enhance the scattering intensity against green visible light to minimize the difference in scattering intensity between green visible light and blue visible light, by reducing
  • the difference in scattering is used to reduce the difference in projection display, which in turn improves the quality of the projection.
  • the scattering layer further includes green-light resonant particles having a diameter within a range of green light balance diameters and located Red light resonance particles in a red light balance diameter range; wherein the red light resonance particles generate a plasmon resonance effect under red visible light to enhance the scattering intensity of the red visible light, and the green light resonance particles generate plasmon resonance under green visible light
  • the effect is to enhance the scattering intensity to the green visible light such that the difference between the scattering intensity of the scattering layer for any two of the visible light, the green visible light, and the red visible light is less than the preset equilibrium scattering intensity.
  • red light resonance particles and green light resonance particles can be simultaneously incorporated in the scattering layer, so that the difference in scattering intensity between the three visible light beams can be reduced to a large extent, so as to minimize the three primary colors. Improve the quality of the projection by making the difference in display.
  • the projection screen is for presenting an image in a rear projection system
  • the thickness of the scattering layer is less than the minimum length of the horizontal length and the vertical length of a single pixel in the image presented by the projection screen.
  • the thickness of the scattering layer can be determined by a single pixel of the screen when the image is projected, so that crosstalk between the pixels when the screen is projected can be avoided as much as possible, thereby improving The projection quality of the screen.
  • the rear projection system further includes a spatial light modulator, the setting Between the depth acquisition device and the projection screen, it is used to modulate the invisible light so that the invisible light is projected to the designated area.
  • the invisible light projected by the depth acquisition device is modulated by the spatial light modulator and then projected to a designated area, which can improve the utilization efficiency of the invisible light to a certain extent, thereby reducing waste of resources.
  • a screen is provided, one side of which is covered with a scattering layer for Rayleigh scattering of visible light from one side of the screen, which can cause another screen located on the screen
  • the user on the side does not see the object located on one side of the screen; and the wavelength of the invisible light is greater than the wavelength of visible light, the scattering intensity of the scattering layer to visible light is greater than the scattering intensity of the scattering layer to the invisible light, so that the invisible light can penetrate Over the screen.
  • the projection device is generally projected with blue add-on, green visible light, and red visible light
  • the blue add-on, green visible light, and red visible light can be projected to
  • the screen cannot reach the user's eyes, that is, the screen is equivalent to a physical block for the user, so that the user can see the screen as much as possible while ensuring a good projection quality to meet the user's projection needs.
  • the object placed at the rear makes the viewing better, which enhances the user's viewing experience.
  • the depth acquisition device generally collects depth information by infrared light
  • the screen has an approximately transparent or completely transparent characteristic to the infrared light from one side of the screen, then At this time, the infrared light can be directly projected through the screen to the other side of the screen to accurately collect the depth information of the object on the other side of the screen, and meet the user's demand for depth information collection.
  • the scattering layer comprises scattering particles having a diameter within a Rayleigh scattering diameter range, and the Rayleigh scattering diameter range is such that the scattering particles are visible to visible light and invisible light Scattering is performed by means of scattering.
  • the scattering layer further includes red-light resonant particles having a diameter within a range of red light balance diameters;
  • the red-light resonance particle generates a plasmon resonance effect under red visible light to enhance the scattering intensity of the red visible light, so that the difference between the scattering intensity of the scattering layer to the red visible light and the scattering intensity of the scattering layer to the blue visible light is less than a preset The red light balances the scattering intensity.
  • the visible light projected by the projection device includes blue visible light and green visible light
  • the scattering layer further includes a diameter Green light resonance particles in the green light balance diameter range; wherein the green light resonance particles generate a plasmon resonance effect under green visible light to enhance the scattering intensity to the green visible light, so that the scattering intensity of the scattering layer to the green visible light and the scattering layer to the blue Scattering intensity of visible light The difference between the differences is less than the preset green light balance scattering intensity.
  • the visible light projected by the projection device includes blue visible light, green visible light, and red visible light; and the scattering layer is further The invention comprises a green light resonance particle having a diameter in a green light balance diameter range and a red light resonance particle in a red light balance diameter range; wherein the red light resonance particle generates a plasmon resonance effect under red visible light to enhance scattering of red visible light
  • the intensity, green-light resonant particles produce a plasmon resonance effect under green visible light to enhance the scattering intensity against green visible light such that the scattering layer is between the scattering intensity of any two of visible light, green visible light, and red visible light.
  • the difference is less than the preset equilibrium scattering intensity.
  • the screen is used for presenting images in a rear projection system,
  • the thickness of the scattering layer is less than the minimum length of the horizontal and vertical lengths of a single pixel in the image.
  • FIG. 1 is a schematic structural diagram of a rear projection system according to an embodiment of the present invention.
  • FIG. 2 is another schematic structural diagram of a rear projection system according to an embodiment of the present invention.
  • 3 is a diagram showing a correspondence relationship between scattering intensity and wavelength when a scattering layer is subjected to Rayleigh scattering according to an embodiment of the present invention
  • FIG. 4 is a schematic structural diagram of a projection system further including a spatial light modulator according to an embodiment of the present invention
  • FIG. 5A is a schematic diagram of determining a region of interest according to an embodiment of the present invention.
  • FIG. 5B is another schematic diagram of determining a region of interest according to an embodiment of the present invention.
  • Figure 6 is a side view of a screen according to an embodiment of the present invention.
  • FIG. 7 is another side view of a screen according to an embodiment of the present invention.
  • an embodiment of the present invention provides a rear projection system including a projection screen 1 , a projection device 2 , and a depth acquisition device 3 .
  • the projection screen 1 is for presenting an image
  • the projection screen 1 comprises a scattering layer 11 capable of scattering light
  • the scattering layer 11 may comprise a scattering medium capable of scattering light
  • the scattering medium may for example comprise scattering particles, due to
  • the scattering layer 11 included in the projection screen 1 is capable of scattering light, so the projection screen 1 in the embodiment of the present invention can be referred to as a scattering projection screen.
  • the projection device 2 is configured to project visible light to the projection screen 1, and the visible light projected by the projection screen 1 includes information of the image to be projected, so that the image can be presented on the projection screen 1 by projecting visible light, that is, the projection screen 1 can be used as The image bearing surface of the image to be projected is image rendered.
  • the projection device 2 is located behind the projection screen 1, for example, the rear of the projection screen 1 is referred to as the side of the projection screen 1.
  • the side of the projection screen 1 For example, in FIG.
  • One side of the screen 1 is regarded as the side on which the projection device 2 is located, that is, the left side of the projection screen 1 can be referred to as the side of the projection screen 1, and the right side of the projection screen 2 is referred to as the other side of the projection screen 1. .
  • the depth acquisition device 3 is also located on one side of the projection screen 1, that is to say, in the embodiment of the invention, the depth acquisition device 3 and the projection device 2 are located on the same side of the projection screen 1.
  • the projection set Both the standby device 2 and the depth acquisition device 3 can be disposed at any position within the rear spatial extent of the projection screen 1, as long as the projection device 2 can be normally projected to the projection screen 1, and the depth acquisition device 3 can capture the front of the projection screen 1.
  • the depth information of the object may be.
  • the projection device 2 and the depth acquisition device 3 may not be located at a line perpendicular to the projection screen 1.
  • the visible light projected by the projection device 2 can be prevented from being blocked by the depth acquisition device 3, or the invisible light projected by the depth acquisition device 3 can be prevented from being blocked by the projection device 2, so that the projection and the depth acquisition can be prevented from affecting each other.
  • the depth acquisition device 3 is for projecting invisible light to an object located on the other side of the projection screen 1 through the projection screen 1, that is, the invisible light projected by the depth acquisition device 3 can be projected to the other side of the projection screen 1 through the projection screen 1
  • the depth acquisition device 3 located on the left side of the projection screen 1 can project invisible light to a person located on the right side of the projection screen 1, and in order to facilitate the reader's understanding, the depth acquisition is performed in FIG.
  • the beam of invisible light projected by device 3 is indicated by a dashed line.
  • a diffuse reflection may be formed on the surface of the object to generate the reflected light, and the depth collecting device 3 obtains the reflected light transmitted through the projection screen 1 to obtain the depth information of the object according to the obtained reflected light.
  • the depth acquisition device 3 may be disposed behind the projection screen 1, that is, disposed on one side of the projection screen 1, since the depth collection device 3 may be disposed in any space within the space behind the projection screen 1. Position, since its position is adjustable, the range of the depth acquisition device 3 can be dynamically changed by changing the position of the depth acquisition device 3 to ensure that it can collect the depth information of the image in front of the projection screen 1 as completely as possible to improve The accuracy of depth information collection.
  • the depth collecting device 3 is a device capable of collecting depth information of an object, and may include any device capable of collecting depth information in the prior art.
  • the device for collecting the depth information of the object obtains depth information by, for example, transmitting invisible light (for example, infrared light).
  • Microsoft Corporation's Kinect which includes an infrared emitter and an infrared camera, passes through The infrared emitter projects the emitted infrared light into the visible range of Kinect, infrared The light produces diffuse reflection on the surface of the object, the infrared camera receives the diffuse reflection light, and then uses the optical coding technique and a predetermined algorithm to obtain a depth image data stream, thereby obtaining the depth information of the object.
  • the depth acquisition device can also include, for example, RGB (Red, Green, and Blue) cameras, and the image information of the object can be acquired by the RGB camera, so that the color image and the depth image in the scene can be simultaneously captured.
  • RGB Red, Green, and Blue
  • the depth acquisition device 3 can be designed to integrate the infrared emitter and the infrared camera into one body, that is, for example, the depth acquisition device 3 in FIG. 1 can simultaneously integrate an infrared emitter and The infrared camera, or, as shown in FIG. 2, the infrared emitter and the infrared camera are separately disposed in the rear projection system.
  • the depth information of the object may include the distance between the object and the depth collecting device 3, and the object is a user A.
  • the depth information can be used in image processing techniques such as three-dimensional object modeling, image segmentation and image fusion.
  • the wavelength of the invisible light is greater than the wavelength of the visible light, that is, the wavelength of the invisible light projected by the depth collecting device 3 is greater than the wavelength of the visible light projected by the projection device 1, for example, the invisible light includes infrared light and far infrared light, that is, The depth acquisition device 3 can project infrared light or far infrared light, and the projection device can project three primary colors of light, that is, blue visible light, green visible light, and red visible light.
  • the scattering intensity of the scattering layer 11 in the projection screen 1 to the visible light is greater than the scattering intensity of the scattering layer 11 to the invisible light, that is, the scattering layer 11 projects on the projection device 1.
  • the scattering intensity of the three primary colors of light is greater than the scattering intensity of the infrared light projected by the scattering layer 11 to the depth acquisition device 3.
  • the scattering intensity of the scattering layer 11 to visible light may be made greater than or equal to a first predetermined scattering intensity threshold, such that the scattering intensity of the scattering layer 11 for invisible light is less than or equal to a second predetermined scattering intensity threshold, and the first predetermined scattering intensity threshold is greater than Two predetermined scattering intensity thresholds.
  • the image projected by the projection device 1 can be rendered with better projection quality, and the user located on the other side of the projection screen 1 can be made invisible to the projection screen 1
  • the object on one side can be understood in this way.
  • the projection screen 1 can block the propagation of visible light from the left side thereof, that is, the projection screen 1 has a blocking effect on the visible light from the left side thereof, thereby causing the right side thereof
  • the projection screen 1 has an occlusion effect on the line of sight of the user located on the right side thereof.
  • the low scattering intensity of the invisible light by the scattering layer 11 can make the invisible light projected by the depth collecting device 3 pass through the projection screen 1 to be projected onto the object located on the other side of the projection screen 1 to obtain the object.
  • Depth information for example, through the projection screen 1 to be projected onto a person on the right side of the projection screen 1 as shown in FIG. 1, so that for the projection screen 1, there is a need for near-transparent or nearly transparent transmission of invisible light.
  • the characteristic is that the scattering intensity of the scattering layer 11 for the invisible light is required to be as small as possible or not scattered at all, and then the scattering layer 11 having a low scattering intensity for invisible light can be used.
  • the scattering intensity of light ranges from [0, 1]. When the scattering intensity is 1, it indicates complete scattering. When the scattering intensity is 0, it indicates no scattering. That is, the larger the value indicates the stronger the scattering intensity, then for example, The scattering layer 11 having a scattering intensity of visible light of 0, 0.2 or 0.3, etc., the smaller the value of the scattering intensity, the lower the scattering intensity of the scattering layer 11 for invisible light, and the invisible light projected by the depth collecting device 3 It is possible to project as much as possible through the projection screen 1 onto an object located on the right side of the projection screen 1, and the depth acquisition device 3 can also obtain diffuse reflection light that is as complete and effective as possible so that the object can be collected as completely and accurately as possible. Depth information to improve the accuracy of deep information collection.
  • the scattering intensity of the visible light projected by the scattering layer 11 on the projection device 2 can be as large as possible, so that the scattering intensity of the scattered light projected by the scattering layer 11 on the projection device 2 can be made. More than the scattering intensity of the invisible light projected by the scattering layer on the depth collecting device 3, for example, the scattering intensity of the scattering layer 11 to the invisible light projected by the depth collecting device 3 is 0.1, and the scattering intensity of the visible light projected by the projection device 2 is 0.9, etc., such that the visible light that is easy to carry image information can be projected onto the projection screen 1 as completely as possible, so that the image to be projected is completely and effectively presented through the projection screen 1 to meet the projection requirements of the user.
  • the scattering layer 11 included in the projection screen 1 in the embodiment of the present invention has a scattering effect on the visible light projected by the projection device 1 and the invisible light projected by the depth capturing device 3, and the scattering of visible light projected by the projection device 1 The intensity is greater than the intensity of the scattering of the invisible light projected by the depth acquisition device 3.
  • the scattering of light can generally be divided into three categories, namely Rayleigh scattering, Mie scattering and hybrid scattering, and the type of scattering is mainly related to the size (ie diameter) of the scattering particles.
  • Rayleigh scattering occurs when the diameter of the scattering particles is much smaller than the wavelength of the incident light, such as typically less than one tenth of the wavelength of the incident light.
  • Rayleigh scattering has the following characteristics: one is that the scattering intensity is inversely proportional to the fourth power of the wavelength of the incident light, and the other is that the scattered light fluxes of the first half and the second half of the scattering particles are equal.
  • scattering including both Rayleigh scattering and Mie scattering can be referred to as hybrid scattering.
  • the wavelength range of visible light is about 380 nm-770 nm, wherein the wavelength range of blue visible light is 455 nm-492 nm, the wavelength range of green visible light is 492 nm-577 nm, the wavelength range of red visible light is 622 nm-770 nm, and the wavelength of infrared light is generally Above 770 nm, the wavelength range of, for example, near-infrared light is approximately 780 nm to 2000 nm. For the convenience of the following description, the following description will be made by taking visible light including 475 nm blue visible light, 525 nm green visible light, and 685 nm red visible light, and invisible light including 1065 nm infrared light.
  • the scattering layer 11 In order to make the scattering layer 11 have a large scattering intensity for visible light and a small scattering intensity for invisible light, and because the wavelength of the invisible light is larger than the wavelength of visible light, the scattering characteristics of Rayleigh scattering in various types of scattering It is determined that the scattering intensity decreases as the wavelength increases, and the scattering intensity is inversely proportional to the fourth power of the wavelength of the incident light, indicating that the scattering intensity decreases with increasing wavelength, which is also relatively large.
  • the requirements of the scattering layer 11 in the embodiment of the present invention are met. Therefore, the embodiment of the present invention utilizes the characteristics of Rayleigh scattering to satisfy the scattering intensity of the scattering layer 11 for visible light and invisible light, that is, the scattering layer in the embodiment of the present invention. 11 scattering with Rayleigh scattering
  • the scattering layer 11 is capable of Rayleigh scattering for both invisible light and visible light.
  • the scattering effect of the scattering layer 11 in the projection screen 1 can be used to ensure that the depth acquisition device located behind the projection screen 1 accurately collects the object located in front of it, and also ensures that the object is located at the same time.
  • the normal projection of the projection device 2 behind the projection screen 1 satisfies the projection requirements of the user, and additionally, the projection screen 1 can also block the object located behind it, so that other objects can be placed in the space behind the projection screen 1.
  • the viewing causes interference and influence, which in turn can improve the user's viewing experience.
  • the depth collecting device 3 since the depth collecting device 3 is placed behind the projection screen 1, the appearance of the front side of the projection screen 1 can be ensured as much as possible, and the projection system can be cleaned.
  • the image formed by the projection device on the projection screen is visible, but the object behind the projection screen is not visible.
  • This phenomenon can be first seen with reference to the object behind the rear projection TV screen but the rear projection TV. It can be imaged, or when the object is close to the frosted glass, the outline of the object can be seen through the frosted glass.
  • the specific principle may be that when the object on the other side of the projection screen is far from the projection screen, the surface of the object is reflected. Visible light (the object is equivalent to the light source) is scattered after a certain length of propagation, and it is difficult for the human eye to determine the position of the light source according to the reverse propagation direction of the scattered visible light, but the projection device can focus the light on the projection screen.
  • the scattering layer 11 may include scattering particles having a diameter in the Rayleigh scattering diameter range, and the Rayleigh scattering diameter range may be such that the scattering particles Both visible light and invisible light can be scattered by Rayleigh scattering.
  • the scattering particles included in the scattering layer 11 may be filled in the transparent base material at equal intervals or unequal intervals by a specific process, or the scattering particles may also be coated on the surface of the transparent base material.
  • the scattering particles may be opaque particles, so as to ensure the scattering effect of the scattering layer 11 on the light, the embodiment of the present invention does not specifically limit the specific form of the scattering particles disposed on the projection screen 1 and the material of the scattered particles, as long as It is sufficient to satisfy the characteristics that the projection screen 1 has Rayleigh scattering for both the visible light projected by the projection device 1 and the invisible light projected by the depth acquisition device 3.
  • scattering particles having a diameter much smaller than the wavelength of the incident light can be used as the scattering medium in the scattering layer 11, and Rayleigh scattering can also be performed for the blue visible light having the smallest wavelength.
  • the diameter of the scattering particles can be determined based on the wavelength of the blue visible light (ie, 475 nm), that is, the Rayleigh scattering diameter range can be determined.
  • the scattering layer 11 can be composed of scattering particles having a diameter of less than 30 nm, that is, the Rayleigh scattering diameter range is ( 0, 30 nm], alternatively, considering that the scattering particles can be uniformly filled in the scattering layer 11, or the Rayleigh scattering diameter range can be set to [20 nm, 30 nm], alternatively, the diameter can be 28 nm.
  • the scattering particles constitute the scattering layer 11, and so on.
  • FIG. 3 is a diagram showing the relationship between the scattering intensity and the wavelength of the scattering layer 11 composed of scattering particles having a diameter of 28 nm in the embodiment of the present invention, wherein the abscissa indicates the wavelength and the ordinate indicates the scattering intensity. It can be seen that as the wavelength increases, the scattering intensity tends to decrease greatly, and at 1065 nm, the scattering intensity is close to 0.
  • the scattering layer 13 has an approximately transparent characteristic for the infrared light of 1065 nm, which can make The infrared light emitted by the depth acquisition device 3 can be transmitted through the projection screen 1 with a large intensity and projected onto the object in front of the projection screen 1 so that the depth acquisition device 3 can acquire the depth information of the object as accurately as possible.
  • the projection screen 1 can provide an approximately transparent characteristic for the infrared light, so that the accuracy of the depth information collection can be ensured as much as possible, but since the scattering intensity increases with wavelength The amplitude is weakened, and the wavelengths of the three kinds of visible light projected by the projection device 2 are also different, so for the three kinds of visible light that are both projected by the projection device 2
  • the difference between the scattering intensities is also large, which may result in excessive scattering of the three primary colors when the projection is performed. For example, when the scattering intensity of the blue visible light is too large and the scattering intensity of the red visible light is low, the entire projection picture will be A blue (ie, cool) tone is applied, which affects the projected quality of the projected image.
  • the embodiment of the present invention can perform the doping on the basis of the scattering particles of the Rayleigh scattering diameter range included in the scattering layer 11.
  • Miscellaneous, plasmon resonance effect is performed by the doped scattering particles to enhance the scattering intensity of the scattering layer 11 for light of a specific wavelength, thereby enhancing scattering of visible light having low scattering intensity (for example, red visible light or green colored light) Intensity to minimize the difference between the scattering intensities of several visible light and reduce the differential display.
  • the plasmon resonance effect is a physical phenomenon that can cause metal free electrons when incident light enters the interface of two different refractive indices at a critical angle.
  • the resonance causes the electrons to absorb the light energy due to the resonance, so that the reflected light is greatly attenuated within a certain angle, and the scattering effect is enhanced, thereby enhancing the scattering intensity of the light.
  • red light resonance particles in a range of red light balance diameters are incorporated.
  • green photoresonant particles in the range of green light balance diameters are incorporated on the basis of scattering particles having a Rayleigh scattering diameter range.
  • the red light resonance particles in the red light balance diameter range and the green light resonance particles in the green light balance diameter range are simultaneously incorporated.
  • the red-light resonant particles can generate a plasmon resonance effect under red visible light to enhance the scattering intensity to the red visible light such that the scattering intensity of the scattering layer 11 to the red visible light and the scattering intensity of the scattering layer 11 to the blue visible light The difference is less than the preset red balance scattering intensity.
  • the green light resonance particles can generate a plasmon resonance effect under green visible light to enhance the scattering intensity to the green visible light so that the scattering intensity of the scattering layer 11 against the green visible light and the scattering intensity of the scattering layer 11 to the blue visible light are different.
  • the value is less than the preset green light balance scattering intensity.
  • the difference between the scattering intensity of the scattering layer 11 for any two of the visible light, the green visible light, and the red visible light may be made smaller than the preset Balance the scattering intensity.
  • the scattering intensity at the Rayleigh scattering is the largest, so the red light of the red light balance diameter range can be incorporated based on the scattering intensity of the blue visible light.
  • the red light resonance particles and the green light resonance can be respectively The plasmon resonance effect of the particles to enhance the scattering intensity of the scattering layer 11 against the red visible light and the green visible light, respectively, such that the difference between the scattering intensity of the scattering layer 11 for any two of the visible light, the green visible light, and the red visible light
  • the values are all smaller than the preset equilibrium scattering intensity, that is, the doping manner in the embodiment of the present invention can greatly reduce the difference in the scattering intensity between the three visible light beams to minimize the three primary colors. Improve the quality of the projection by making the difference in display.
  • the preset red light balance scattering intensity and the preset green light balance scattering intensity may be the same, for example, all of 0.05, or may be different, for example, the preset red light balance scattering intensity is 0.05, and the preset green light balance is preset.
  • the scattering intensity is 0.03.
  • the preset equilibrium scattering intensity may be equal to the preset red light balance scattering intensity, that is, 0.05, or may be equal to the preset green light balance scattering intensity, that is, 0.03, or For other values, for example, 0.02, that is, the preset equilibrium scattering intensity may be the same or different from the preset green light balance scattering intensity and the preset red light balance scattering intensity. It is assumed that the scattering intensity of the scattering layer 11 for blue visible light, green visible light, and red visible light is x, y, respectively. z, then the values of x-y, x-z, and y-z can be required to be less than the preset equilibrium scattering intensity, so as to minimize the difference in scattering intensity between the three primary colors to maximize the quality of the projection.
  • the scattering intensities of the scattering layer 11 for blue visible light, green visible light, and red visible light are 0.98, 0.9, and 0.82, respectively, before doping, and after simultaneously incorporating the red light resonant particles and the green light resonant particles, the scattering layer 11
  • the scattering intensities for blue visible light, green visible light, and red visible light are 0.98, 0.95, and 0.94, respectively. It can be seen that after doping, the scattering intensity of the scattering layer 11 for both green visible light and red visible light is increased.
  • the scattering intensity of the red visible light with the Rayleigh scattering scattering layer 11 before the undoping is the lowest, that is, the difference between the scattering intensity between the red visible light and the blue visible light is It is larger than the difference in scattering intensity between green visible light and blue visible light. Therefore, in order to minimize the difference in scattering intensity between the three primary colors, the scattering intensity for red visible light can be enhanced as much as possible during doping.
  • the red light resonance particle of the red light balance diameter range may include, for example, a silica nano gold shell or the like, which may resonate at a wavelength of 700 nm to enhance the scattering intensity of red visible light.
  • the silica nano gold shell in the embodiment of the present invention may have a hollow shell shape, and has an outer diameter of about 80 nm and an inner diameter of about 20 cm, that is, a hollow shell having a thickness of about 60 nm.
  • the green resonance particles of the green light balance diameter range may include, for example, gold nanospheres having a diameter of 80 to 100 nm, etc., and these particles may resonate at a wavelength of 550 nm to enhance the scattering intensity of green visible light.
  • the red light resonance particle of the red light balance diameter range and the green light resonance particle of the green light balance diameter range include, but are not limited to, the two listed above, as long as it can be used for resonance under red visible light to enhance the scattering intensity of red visible light.
  • the scattering particles can be used as red-light resonance particles in the red light balance diameter range, and as long as the resonance particles can be used to resonate under green visible light to enhance the scattering intensity of green visible light, the green light resonance can be used as the green light balance diameter range.
  • the particles are not limited in the embodiment of the invention.
  • the thickness d of the scattering layer 11 can be set to be smaller than that in the embodiment of the present invention, in order to prevent the projection image of the projection screen 1 from causing crosstalk between the pixels to affect the projection quality of the projection screen 1.
  • the first length in particular, the first length is the smaller of the horizontal length and the vertical length of the projection pixels of the projection screen 1, ie the first length is the smallest of the horizontal length and the vertical length of the single pixel in the projected image length.
  • the first length can be determined according to the projection resolution of the projection device 2 shown in FIG. 1 or FIG. 2 and the minimum projection size that the projection device 2 can project, that is, according to the projection resolution of the projection device 2 and the projection device 2
  • the minimum projected size of the projection determines the thickness d of the scattering layer 11.
  • the horizontal length of the projection pixel of the projection screen 1 W min /D x
  • the first length is the smaller of W min /D x and H min /D y .
  • D x and D y represent the lateral resolution and the vertical resolution of the projection resolution of the projection device 2, respectively, for example, 1024 pixels ⁇ 768 pixels, and W min and H min respectively represent the widths of the minimum projection size of the projection device 2 and
  • the height for example, can also be expressed in pixels, for example 256 pixels x 192 pixels.
  • the thickness of the scattering layer 11 can be determined by projecting a single pixel of the screen 1 when the image is projected, so that crosstalk between the pixels when the projection screen 1 is projected can be avoided as much as possible, thereby improving the projection.
  • the projection quality of screen 1 to enhance the performance of this projection system.
  • the depth acquisition device 3 generally projects invisible light to the entire coverage, for example, objects such as tables, chairs and flower pots in the conference room are projected. Invisible light, which may result in waste of resources.
  • the projection system of the embodiment of the present invention may further include a spatial light modulator 4, the spatial light modulator 4 may be connected to the depth acquisition device 3, and the spatial light modulator 4 is set at a depth. Between the acquisition device 3 and the projection screen 1, it is used to project the invisible light emitted by the depth acquisition device 3 to a specified projection area, that is, to the area where the object that needs to collect the depth information is located.
  • the invisible light is spatially modulated to project the invisible light region, so that it is not necessary to project a large range of invisible light through the depth collecting device 3 every time, so as to minimize the waste of invisible light, improve the utilization efficiency of the invisible light, and reduce Waste of resources.
  • the energy of all the light projected by the depth acquisition device 3 can be concentrated and then projected onto the designated area, and then the energy of the invisible light projected to the designated area and the modulation before The energy is equal, which is equivalent to the modulation of the spatial light modulator 4, the total energy of the projected light is constant, and the energy is redistributed to maximize the accuracy of the depth information acquisition.
  • the energy of the invisible light projected to the designated area is unchanged before the modulation, so that resources can be saved as much as possible to avoid waste.
  • the region of interest Before the invisible light is modulated by the spatial light modulator 4, the region of interest needs to be determined before the partition projection. For example, as shown in FIG. 4, the region where the two participants in the scene are located can be determined as the region of interest. In a specific implementation process, for example, the region of interest may be determined by manually setting, or the projection system may also automatically determine the region of interest by means of image recognition, and the like.
  • the area indicated by the rectangular frame 50 is the entire area of the scene in front of the projection screen 1, and there are three participants in the scene, and the area where the three participants are located can be determined as the area of interest.
  • the area in which the three participants are connected ie, the area indicated by the rectangular frame 51
  • the region of interest may be determined as shown in FIG. 5A, or, in order to maximize For the utilization of invisible light, it is also possible to determine the regions in which the three participants are located as the regions of interest, that is, to determine the three regions of interest, as shown in FIG. 5B.
  • the hologram of the region of interest may be calculated by a predetermined algorithm, such as an Iterative Fourier Transform Algorithm (IFTA) or Single pixel flipping algorithms, and so on. Further, after obtaining the hologram of the region of interest, a corresponding control signal can be generated and sent to the spatial light modulator 4, which can be transmitted to the depth acquisition device 3 after receiving the control signal by the spatial light modulator 4 The invisible light is redistributed to project to a predetermined region of interest.
  • IFTA Iterative Fourier Transform Algorithm
  • Single pixel flipping algorithms and so on.
  • an embodiment of the present invention provides a screen 60.
  • One side of the screen 60 is covered with a scattering layer 11, that is, the screen 60 includes a scattering layer 11 for Rayleigh scattering of visible light from one side of the screen 60. So that the user located on the other side of the screen 60 does not see an object located on one side of the screen 60, that is, in the embodiment of the invention, the scattering of visible light from the side of the screen 60 by the scattering layer 11 Acting, screen 60 can be made to have an occlusion effect on the line of sight of the user located on the other side of screen 60.
  • the screen 60 in the embodiment of the present invention can be applied to the rear projection system shown in any of FIG. 1 to FIG. 4, that is, the screen 60 in the embodiment of the present invention can be used instead of any of FIG. 1 to FIG. 6. Projection screen 1 in the rear projection system shown.
  • the scattering intensity of the scattering layer 11 in the screen 60 is greater than the scattering intensity of the scattering layer 11 to the invisible light.
  • the wavelength of the invisible light is greater than the wavelength of the visible light.
  • the visible light may include, for example, three primary colors of light, that is, including blue. Addable light, green visible light and red visible light, invisible light including infrared light or far infrared light, etc., for example, the scattering intensity of the scattering layer 11 for blue visible light, green visible light and red visible light is 0.98, 0.93 and 0.89, respectively.
  • the scattering intensity of infrared light is 0.11.
  • the projection device is generally projected with blue add-on, green visible light, and red visible light
  • the blue add-on, green visible light, and red visible light can be projected to
  • the screen 60 the user's eyes cannot be reached, that is, the screen 60 is equivalent to a physical block for the user, so that the user can be avoided as much as possible while ensuring a good projection quality to meet the user's projection requirements.
  • the object placed behind the screen 60 makes the viewing effect more, thereby enhancing the user's viewing experience.
  • the depth acquisition device generally collects depth information by infrared light
  • the screen 60 is infrared to the side from the screen 60 when the infrared light is scattered with a lower scattering intensity.
  • the light has a characteristic of being substantially transparent or completely transparent, and then the infrared light can be directly projected through the screen 60 to the other side of the screen 60 to achieve accurate collection of depth information of the object on the other side of the screen 60, satisfying the user. The need for deep information collection.
  • the screen 60 further includes a first surface 71 and a second surface 72, and the scattering layer 11 is located between the first surface 71 and the second surface 72, and the thickness of the scattering layer 11 is assumed to be d.
  • the screen 60 can provide the projected image to the viewer via the second side 72, i.e., the image can be rendered by the second side 72, that is, the second side 72 can be used as the projected front of the screen 60 when the user is on the screen 60. In the forward direction, the projected image on the second side 72 can be seen by the reflection of the light on the second side 72.
  • the first side 71 and the second side 72 of the screen 60 may include a transmissive film that transmits light, that is, the first side 71 and the second side 72 have transmission to both visible light and invisible light in the embodiment of the present invention.
  • the first surface 71 and the second surface 72 are equivalent to being transparent to visible light and invisible light in the embodiment of the present invention.
  • the first surface 71 and the second surface 72 may further include other structures capable of supporting, only need to ensure that visible light and invisible light can be transmitted, and the first surface
  • the 71 and second face 72 may have a thickness, such as a transmissive film having a thickness, and the like.

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Abstract

一种背投系统及屏幕，用于在实现深度信息采集的同时增强用户的观看感受。所述投影系统包括：包括散射层（11）的投影屏幕（1），用于呈现图像；投影设备（2），用于向投影屏幕（1）投射可见光，以使得投影屏幕（1）呈现图像；深度采集设备（3），与投影设备（2）位于所述投影屏幕（1）的同一侧，用于通过投影屏幕（1）向位于投影屏幕的另一侧的对象投射不可见光，以及接收对象对不可见光进行反射的反射光，进而获得对象的深度信息，不可见光的波长大于可见光的波长；其中，散射层（11）对来自投影屏幕的一侧的可见光和不可见光进行瑞利散射，散射层（11）对可见光的散射强度大于散射层对不可见光的散射强度。

Description

一种背投系统及屏幕
本申请要求在2016年04月19日提交中国专利局、申请号为201610244690.4、发明名称为“一种背投系统及屏幕”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本发明涉及投影技术领域，尤其涉及一种背投系统及屏幕。
背景技术
根据投影机设置在投影系统中的位置，可以将投影系统分为前投影系统和背投影系统，一般将投影机设置于投影屏幕后方的投影系统称作背投影系统，也称背投系统，由于可将投影设备隐藏地放置于投影屏幕背后，用户在观看投影的过程中可以不用看到投影设备，对用户来说感觉更好，因此背投系统已广泛应用于多种场景，例如远程视频会议场景或家庭娱乐场景，等等。
在使用背投系统的过程中，在较多情形下可能需要采集场景中对象的深度信息，例如在远程会议视频场景中，需要采集主讲人员的图像信息以传递给会议对端，为了能够获得较好的图像质量，也就还需要采集主讲人员的深度信息，例如将采集深度信息的设备称作深度采集设备。例如深度采集设备一般包括红外发射器和红外摄像头，红外发射器发射不可见光，例如红外光，红外光在主讲人员表面形成漫反射，再通过红外摄像头获得反射回的红外光，通过反射回的红外光就可以获得主讲人员的深度信息。
一般地可以将深度采集设备设置于投影屏幕的后方，并将投影屏幕设置为透光的，这样深度采集设备所投射的红外光能够透过投影屏幕而投射到投影屏幕前方的物体上进而实现深度信息的采集，然而这也使得位于投影屏幕前方的用户除了能看到投影的图像，也能够看到投影屏幕后方的物体，例如投影设备、深度采集设备和其它物体，进而干扰投影图像的观看效果以及影响用户的观看体验，另外，例如投影设备的光源(例如灯泡)也可能刺射到 用户的眼睛，影响用户对投影图像的观看感受。
发明内容
本发明实施例提供一种背投系统及屏幕，用于在实现深度信息采集的同时，增强用户的观看感受。
第一方面，提供一种背投系统，该背投系统包括投影屏幕、投影设备和深度采集设备。其中，投影屏幕包括散射层，用于呈现图像；投影设备用于向投影屏幕投射可见光以使得投影屏幕呈现图像；深度采集设备，与投影设备位于投影屏幕的同一侧，用于通过投影屏幕向位于投影屏幕的另一侧的对象投射不可见光，以及接收对象对不可见光进行反射的反射光，进而获得对象的深度信息；其中，散射层用于对来自所述投影屏幕的一侧的可见光和不可见光进行瑞利散射，并且散射层对可见光的散射轻度对于散射层对不可见光的散射强度，这样可以使得位于投影屏幕的另一侧的用户看不到位于投影屏幕的一侧的物体，并使得深度采集设备能够获得对象的深度信息。
本发明实施例中，不可见光的波长大于可见光的波长，例如，可见光包括三基色光，即包括蓝色可加光、绿色可见光和红色可见光，不可见光包括红外光或远红外光。
本发明实施例中，可以将位于投影屏幕的一侧看作是位于投影屏幕的后方，即投影设备和深度采集设备均位于投影屏幕的后方，通过投影屏幕中的散射层的散射作用，可以用于确保位于投影屏幕后方的深度采集设备对位于投影屏幕前方的对象准确地进行深度采集，同时还可以确保位于投影屏幕后的投影设备的正常投影，满足用户的投影需求，另外由于投影屏幕还可以对位于其后方的物体起到遮挡作用，这样使得用于无法看到位于投影屏幕后方的对象，例如看不到位于投影屏幕后的投影设备和深度采集设备，这样可以在投影屏幕后方的空间内放置其它物体，提高空间利用率，并且当投影屏幕足够大的时候，相当于是在用户前方放置了一堵幕墙，投影设备所包括的光源或者深度采集设备上一些指示灯均无法对用户对投影图像的观看造成干扰 和影响，进而可以提高用户的观影感受，同时，由于将深度采集设备放置到了投影屏幕的后方，还可以尽量保证投影屏幕正面的美观，提高投影系统的整洁。
另外，由于可以将深度采集设备设置于投影屏幕背后的空间范围内的任意一个位置，基于其位置可调，进而可以通过改变深度采集设备的位置来动态地调整深度采集设备的采集范围，以确保其能够尽量完整地采集投影屏幕前方的图像的深度信息，以提高深度信息采集的准确性。
需要说明的是，之所以投影设备投射出的可见光在投影屏幕上形成的图像可见，而投影屏幕后方的物体却不可见，该现象首先可参照背投电视屏幕后方的物体不可见但背投电视却可以成像，或者参照当物体贴近毛玻璃时，是可以隔着毛玻璃看清物体的轮廓的，具体的原理可以是当投影屏幕的另一侧的物体距离投影屏幕较远时，物体表面反射出的可见光(此时物体相当于光源)在传播了一定长度后才被散射，人眼很难根据散射后的可见光的逆传播方向确定光源位置，但是投影设备能够将可将光聚焦在投影屏幕处，这就等效于投影设备将作为光源的投影图像放在了投影屏幕处，当等效出的投影图像的可见光在开始传播的地方就被散射，即使方向改变了，但投影图像的散射后的可见光的逆传播路径仍然可以聚焦于投影图像处，因此投影图像看起来并没有模糊，因此投影屏幕的散射对投影图像的呈现的影响很低。再者，由于投影屏幕的另一侧的光线很暗，因此投影图像的可见光的强度比物体的可见光强度要高许多，因此投影设备投射出的可见光在投影屏幕上形成的图像可见，然而投影屏幕后方的物体却不可见是可以实现的。
结合第一方面，在第一方面的第一种可能的实现方式中，散射层包括直径位于瑞利散射直径范围内的散射颗粒。其中，位于瑞利散射直径范围使得散射颗粒对可见光以及不可见光以瑞利散射的方式进行散射。
由于瑞利散射的散射强度与入射光的波长的四次方成反比，本发明实施例中，为了使得散射层对于可见光具有较大的散射强度以及对于不可见光具有较小的散射强度，又由于不可见光的波长大于可见光的波长，而在多种类 型的散射中，瑞利散射的散射特性决定了其散射强度是随着波长的增大而减小的，并且散射强度与入射光的波长的四次方成反比，即说明其散射强度随波长增加的降低幅度是比较大的，这也正符合本发明实施例中对于散射层的要求，所以本发明实施例利用瑞利散射的特性来满足散射层对于可见光和不可见光的散射强度的要求，即本发明实施例中的散射层具有瑞利散射的散射特性。
结合第一方面或第一方面的第一种可能的实现方式，在第一方面的第二种可能的实现方式中，投影设备投射的可见光包括蓝色可见光和红色可见光；散射层还包括直径位于红光平衡直径范围内的红光共振颗粒；其中，红光共振颗粒在红色可见光下产生等离子体共振效应以增强对红色可见光的散射强度，使得散射层对红色可见光的散射强度与散射层对蓝色可见光的散射强度之间的差值小于预设的红光平衡散射强度。
本发明实施例中，由于三种可见光中的蓝色可见光的波长最短，在进行瑞利散射时的散射强度是最大的，所以可以以蓝色可见光的散射强度为基准，通过掺入红光平衡直径范围的红光共振颗粒以增强对红色可见光的散射强度，以尽量减小红色可见光与蓝色可见光之间的散射强度的差距，通过降低散射差异来减弱投影显示时的差异，进而提升投影质量。
结合第一方面或第一方面的第一种可能的实现方式，在第一方面的第三种可能的实现方式中，投影设备投射的可见光包括蓝色可见光和绿色可见光；散射层还包括直径位于绿光平衡直径范围内的绿光共振颗粒；其中，绿光共振颗粒在绿色可见光下产生等离子体共振效应以增强对绿色可见光的散射强度，使得散射层对绿色可见光的散射强度与散射层对蓝色可见光的散射强度之间的差值小于预设的绿光平衡散射强度。
本发明实施例中，由于三种可见光中的蓝色可见光的波长最短，在进行瑞利散射时的散射强度是最大的，所以可以以蓝色可见光的散射强度为基准，通过掺入绿光平衡直径范围的绿光共振颗粒以增强对绿色可见光的散射强度，以尽量减小绿色可见光与蓝色可见光之间的散射强度的差距，通过降低 散射差异来减弱投影显示时的差异，进而提升投影质量。
结合第一方面或第一方面的第一种可能的实现方式，在第一方面的第四种可能的实现方式中，散射层还包括直径位于绿光平衡直径范围内的绿光共振颗粒和位于红光平衡直径范围内的红光共振颗粒；其中，红光共振颗粒在红色可见光下产生等离子体共振效应以增强对所述红色可见光的散射强度，绿光共振颗粒在绿色可见光下产生等离子体共振效应以增强对绿色可见光的散射强度，以使得散射层对蓝色可见光、绿色可见光和红色可见光其中的任意两种可见光的散射强度之间的差值均小于预设的平衡散射强度。
本发明实施例中，可以在散射层中同时掺入红光共振颗粒和绿光共振颗粒，这样可以较大程度上减小三种可见光两两之间的散射强度的差距，以尽量减弱三基色在进行显示的差异，提升投影质量。
结合第一方面或第一方面的第一种至第四种中任一种可能的实现方式，在第一方面的第五种可能的实现方式中，投影屏幕用于在背投系统中呈现图像，散射层的厚度小于投影屏幕所呈现的图像中单个像素的水平长度和垂直长度中的最小长度。
本发明实施例中，在本发明实施例中，通过屏幕在投影图像时的单个像素，可以确定散射层的厚度，这样可以尽量避免屏幕在投影图像时的各像素之间产生串扰，进而可以提升屏幕的投影质量。
结合第一方面或第一方面的第一种至第五种中任一种可能的实现方式，在第一方面的第六种可能的实现方式中，背投系统还包括空间光调制器，设置于深度采集设备和投影屏幕之间，用于调制不可见光，使得不可见光投射到指定的区域。
本发明实施例中，通过空间光调制器对深度采集设备所投射的不可见光进行调制后投射到指定的区域，可以在一定程度上提高不可见光的利用效率，进而减少资源的浪费。
第二方面，提供一种屏幕，该屏幕的一侧覆盖有散射层，该散射层用于对来自于屏幕的一侧的可见光进行瑞利散射，这样可以使得位于屏幕的另一 侧的用户看不到位于屏幕的一侧的物体；以及，不可见光的波长大于可见光的波长，该散射层对可见光的散射强度大于该散射层对不可见光的散射强度，以使得不可见光能够透过屏幕。
由于投影设备一般是以蓝色可加光、绿色可见光和红色可见光进行投影，所以当以较高的散射强度对可见光进行散射时，可以使得蓝色可加光、绿色可见光和红色可见光均投射到屏幕上而无法到达用户的眼睛，即此时屏幕对于用户来说相当于是实体阻挡的，这样可以在保证较好的投影质量以满足用户的投影需求的前提下，又可以尽量避免用户看到屏幕后方放置的物体，使得观看效果更佳，进而提升用户的观看感受。
而由于深度采集设备一般通过红外光进行深度信息的采集，所以当以较低的散射强度对红外光进行散射时，屏幕对于来自屏幕的一侧的红外光具有近似透明或完全透明的特性，那么此时红外光可以直接透过屏幕而投射到屏幕的另一侧以实现对屏幕的另一侧的物体的深度信息的准确采集，满足用户对深度信息采集的需求。
结合第二方面，在第二方面的第一种可能的实现方式中，散射层包括直径位于瑞利散射直径范围内的散射颗粒，位于瑞利散射直径范围使得散射颗粒对可见光以及不可见光以瑞利散射的方式进行散射。
结合第二方面或第二方面的第一种可能的实现方式，在第二方面的第二种可能的实现方式中，散射层还包括直径位于红光平衡直径范围内的红光共振颗粒；其中，红光共振颗粒在红色可见光下产生等离子体共振效应以增强对红色可见光的散射强度，使得散射层对红色可见光的散射强度与散射层对蓝色可见光的散射强度之间的差值小于预设的红光平衡散射强度。
结合第二方面或第二方面的第一种可能的实现方式，在第二方面的第三种可能的实现方式中，投影设备投射的可见光包括蓝色可见光和绿色可见光，散射层还包括直径位于绿光平衡直径范围内的绿光共振颗粒；其中，绿光共振颗粒在绿色可见光下产生等离子体共振效应以增强对绿色可见光的散射强度，使得散射层对绿色可见光的散射强度与散射层对蓝色可见光的散射强度 之间的差值小于预设的绿光平衡散射强度。
结合第二方面或第二方面的第一种可能的实现方式，在第二方面的第四种可能的实现方式中，投影设备投射的可见光包括蓝色可见光、绿色可见光和红色可见光；散射层还包括直径位于绿光平衡直径范围内的绿光共振颗粒和位于红光平衡直径范围内的红光共振颗粒；其中，红光共振颗粒在红色可见光下产生等离子体共振效应以增强对红色可见光的散射强度，绿光共振颗粒在绿色可见光下产生等离子体共振效应以增强对绿色可见光的散射强度，以使得散射层对蓝色可见光、绿色可见光和红色可见光其中的任意两种可见光的散射强度之间的差值均小于预设的平衡散射强度。
结合第二方面或第二方面的第一种至第四种中任一种可能的实现方式，在第二方面的第五种可能的实现方式中，屏幕用于背投系统中的呈现图像，散射层的厚度小于图像中单个像素的水平长度和垂直长度中的最小长度。
附图说明
为了更清楚地说明本发明实施例的技术方案，下面将对本发明实施例中所需要使用的附图作简单地介绍，显而易见地，下面所介绍的附图仅仅是本发明的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他的附图。
图1为本发明实施例提供的背投系统的架构示意图；
图2为本发明实施例提供的背投系统的另一架构示意图；
图3为本发明实施例提供的散射层进行瑞利散射时散射强度与波长之间的对应关系图；
图4为本发明实施例提供的还包括空间光调制器的投影系统的架构示意图；
图5A为本发明实施例提供的确定感兴趣区域的示意图；
图5B为本发明实施例提供的确定感兴趣区域的另一示意图；
图6为本发明实施例提供的屏幕的侧视图；
图7为本发明实施例提供的屏幕的另一侧视图。
具体实施方式
为使本发明实施例的目的、技术方案和优点更加清楚，下面将结合本发明实施例中的附图，对本发明实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施例是本发明一部分实施例，而不是全部的实施例。基于本发明中的实施例，本领域普通技术人员在没有作出创造性劳动前提下所获得的所有其他实施例，都属于本发明保护的范围。
为了更好的理解上述技术方案，下面将结合说明书附图以及具体的实施方式对上述技术方案进行详细的说明。
请参见图1，本发明实施例提供一种背投系统，该背投系统包括投影屏幕1、投影设备2和深度采集设备3。
其中，投影屏幕1用于呈现图像，投影屏幕1包括散射层11，散射层11能够对光进行散射，散射层11可以包括对光能够进行散射的散射介质，散射介质例如可以包括散射颗粒，由于投影屏幕1所包括的散射层11能够对光进行散射，所以可以将本发明实施例中的投影屏幕1称作散射投影屏幕。
投影设备2用于向投影屏幕1投射可见光，投影屏幕1所投射的可见光中包括待投影图像的信息，所以进而可以通过投射可见光在投影屏幕1上呈现图像，也就是说，投影屏幕1可以作为待投影图像的投影承载面进行图像呈现。
由于本发明实施例提供的是背投系统，所以投影设备2位于投影屏幕1的后方，例如将投影屏幕1的后方称作投影屏幕1的一侧，以图1为例来说，可以将投影屏幕1的一侧看作是投影设备2所在的一侧，即可以将投影屏幕1的左侧称作投影屏幕1的一侧，将投影屏幕2的右侧称作投影屏幕1的另一侧。
深度采集设备3也位于投影屏幕1的一侧，也就是说，在本发明实施例中，深度采集设备3和投影设备2位于投影屏幕1的同一侧。并且，投影设 备2和深度采集设备3均可以设置于投影屏幕1后方空间范围的任意一处位置，只要保证投影设备2能够向投影屏幕1正常进行投影，以及深度采集设备3能够采集到投影屏幕1前方的物体的深度信息即可，另外，为了避免投影设备2进行投影和深度采集设备3进行深度采集之间的相互影响，投影设备2与深度采集设备3可以不同时位于垂直于投影屏幕1的一条直线上，这样可以避免投影设备2投射的可见光被深度采集设备3遮挡，或者可以避免深度采集设备3投射的不可见光被投影设备2遮挡，从而可以使得投影和深度采集之间互不影响。
深度采集设备3用于通过投影屏幕1向位于投影屏幕1的另一侧的对象投射不可见光，即深度采集设备3投射的不可见光能够透过投影屏幕1而投射到投影屏幕1的另一侧的对象上，例如图1所示，位于投影屏幕1的左侧的深度采集设备3可以向位于投影屏幕1的右侧的人投射不可见光，并且为了便于阅读者理解，图1中通过深度采集设备3所投射的不可见光的光束以虚线表示。当投射的不可见光投射到对象上时可以在对象的表面形成漫反射以产生反射光，深度采集设备3再获得透过投影屏幕1的反射光，进而可以根据获得的反射光获得对象的深度信息。
在本发明实施例中，深度采集设备3可以设置在投影屏幕1的背后，即设置于投影屏幕1的一侧，由于可以将深度采集设备3设置于投影屏幕1背后的空间范围内的任意一个位置，由于其位置可调，所以可以通过改变深度采集设备3的位置来动态地改变深度采集设备3的采集范围，以确保其能够尽量完整地采集投影屏幕1前方的图像的深度信息，以提高深度信息采集的准确性。
本发明实施例中，深度采集设备3为能够采集物体的深度信息的设备，可以包括现有技术中任意一种能够采集深度信息的设备。在具体实施过程中，用以采集物体的深度信息的设备例如是通过发射不可见光(例如红外光)的方式获得深度信息，以微软公司的Kinect为例，Kinect包括红外发射器和红外摄像头，通过红外发射器将发射的红外光投射到Kinect的可视范围，红外 光在物体的表面产生漫反射，红外线摄像头接收漫反射光线，再利用光编码技术和预定的算法以获得深度图像数据流，进而获得物体的深度信息。
另外，深度采集设备还可以同时包括例如RGB(红绿蓝)摄像头，通过RGB摄像头可以采集物体的图像信息，这样能够同时捕获场景中的彩色图像和深度图像。
可选的，类似于Kinect的设计，可以将深度采集设备3设计为将红外发射器和红外摄像头集成为一体的结构，即例如图1中的深度采集设备3中可以同时集成有红外发射器和红外摄像头，或者，还可以如图2所示，将红外发射器和红外摄像头分离设置于背投系统中。
本发明实施例中，物体的深度信息可以包括物体与深度采集设备3之间的距离，以物体是用户甲举例，通过采集用户甲的深度信息，可以分别获得用户甲的鼻尖、额头和嘴唇等身体部位与深度采集设备3之间的距离，深度信息可以用于三维物体建模、图像分割和图像融合等图像处理技术中。
本发明实施例中，不可见光的波长大于可见光的波长，即深度采集设备3所投射的不可见光的波长大于投影设备1所投射的可见光的波长，例如不可见光包括红外光和远红外光，即深度采集设备3可以投射红外光或远红外光，投影设备可以投射三基色光，即投射蓝色可见光、绿色可见光和红色可见光。
本发明实施例中，为了满足投影质量和深度信息采集的要求，投影屏幕1中的散射层11对可见光的散射强度大于散射层11对不可见光的散射强度，即散射层11对投影设备1投射的三基色光的散射强度大于散射层11对深度采集设备3所投射的红外光的散射强度。例如，可以使得散射层11对可见光的散射强度大于等于第一预定散射强度阈值，而使得散射层11对不可见光的散射强度小于等于第二预定散射强度阈值，而第一预定散射强度阈值大于第二预定散射强度阈值。
通过散射层11对可见光的高散射强度，可以使得投影设备1所投影的图像能够以较好投影质量进行呈现，并且可以使得位于投影屏幕1的另一侧的用户看不到位于投影屏幕1的一侧的物体，可以这样理解，以图1为例，通 过散射层11对可见光的散射作用，投影屏幕1可以阻挡来自于其左侧的可见光的传播，即投影屏幕1对来自于其左侧的可见光来说具有阻挡作用，进而导致位于其右侧的用户无法看到其左侧的可见光，自然也无法看到位于其左侧的物体，相当于是，投影屏幕1对于位于其右侧的用户的视线具有遮挡作用。
同时，通过散射层11对不可见光的低散射强度，可以使得深度采集设备3所投射的不可见光能够透过投影屏幕1以投射到位于投影屏幕1的另一侧的对象上进而获得该对象的深度信息，例如透过投影屏幕1以投射到如图1中所示的位于投影屏幕1的右侧的人身上，所以对于投影屏幕1来说，需要对不可见光具有接近透明或近似透明的透射特性，即要求散射层11对于不可见光的散射强度要尽量小或者完全不散射，那么此时可以采用对不可见光的散射强度较低的散射层11。
例如光的散射强度范围为[0，1]，当散射强度为1时表明完全散射，当散射强度为0时表明不散射，即取值越大表明散射强度越强，那么例如可以采用对不可见光的散射强度为0、0.2或0.3等等的散射层11，散射强度的取值越小，那么说明散射层11对于不可见光的散射强度就越低，由深度采集设备3所投射的不可见光就能够尽量多地透过投影屏幕1而投射到位于投影屏幕1右侧的物体上，并且深度采集设备3也能够获得尽量完整且有效的漫反射光，以便能够尽量完整、准确地采集到物体的深度信息，以提高深度信息采集的准确性。
在本发明实施例中，为了保证投影质量，散射层11对投影设备2所投射的可见光的散射强度可以尽可能地大，那么可以令散射层11对投影设备2所述投射的可见光的散射强度大于散射层对深度采集设备3所投射的不可见光的散射强度，例如散射层11对深度采集设备3所投射的不可见光的散射强度为0.1，而对投影设备2所投射的可见光的散射强度为0.9，等等，这样便于携带图像信息的可见光能够尽量完整地投射到投影屏幕1上，以通过投影屏幕1完整、有效地呈现待投影的图像，满足用户的投影需求。
也就是说，本发明实施例中的投影屏幕1所包括的散射层11对于投影设备1投射的可见光和深度采集设备3投射的不可见光均具有散射作用，而对投影设备1投射的可见光的散射强度大于对深度采集设备3投射的不可见光的散射强度。
另外，光的散射一般可以分为三类，即瑞利散射、米氏散射和混合散射，散射的类型主要和散射颗粒的尺寸(即直径)有关。
当散射颗粒的直径远小于入射光的波长时，例如一般小于入射光的波长的十分之一时，将发生瑞利散射。瑞利散射具有如下特点，一是散射强度与入射光的波长的四次方成反比，二是散射颗粒前半部和后半部的散射光通量相等。
当散射颗粒的直径与入射光的波长相当时，将发生米氏散射，米氏散射的散射强度与入射光的波长无关，而且光子散射后的性质一般也不会发生改变。
另外，可以将同时包括瑞利散射和米氏散射的散射称作混合散射。
而可见光的波长范围大约为380nm-770nm，其中，蓝色可见光的波长范围是455nm-492nm，绿色可见光的波长范围是492nm-577nm，红色可见光的波长范围是622nm-770nm，而红外光的波长一般大于770nm，例如近红外光的波长范围大约是780nm-2000nm。为了便于后续描述，以下均以可见光包括475nm的蓝色可见光、525nm的绿色可见光和685nm的红色可见光，以及不可见光包括1065nm的红外光为例进行说明。
为了使得散射层11对可见光具有较大的散射强度以及对不可见光具有较小的散射强度，又由于不可见光的波长大于可见光的波长，而在多种类型的散射中，瑞利散射的散射特性决定了其散射强度是随着波长的增大而减小的，并且散射强度与入射光的波长的四次方成反比，即说明其散射强度随波长增加的降低幅度是比较大的，这也正符合本发明实施例中对于散射层11的要求，所以本发明实施例利用瑞利散射的特性来满足散射层11对于可见光和不可见光的散射强度的要求，即本发明实施例中的散射层11具有瑞利散射的散射特 性，散射层11对不可见光和可见光均能够进行瑞利散射。
本发明实施例中，通过投影屏幕1中的散射层11的散射作用，可以用于确保位于其投影屏幕1后方的深度采集设备对位于其前方的对象准确地进行深度采集，同时还可以确保位于投影屏幕1后的投影设备2的正常投影，满足用户的投影需求，另外由于投影屏幕1还可以对位于其后方的物体起到遮挡作用以，这样可以在投影屏幕1背后的空间放置其它物体，提高空间利用率，并且当投影屏幕1足够大的时候，相当于是在用户前方放置了一堵幕墙，投影设备1所包括的光源或者深度采集设备3上一些指示灯均不会对用户对投影图像的观看造成干扰和影响，进而可以提高用户的观影感受，同时，由于将深度采集设备3放置到了投影屏幕1的后方，还可以尽量保证投影屏幕1正面的美观，提高投影系统的整洁。
需要说明的是，之所以投影设备投射出的可见光在投影屏幕上形成的图像可见，而投影屏幕后方的物体却不可见，该现象首先可参照背投电视屏幕后方的物体不可见但背投电视却可以成像，或者参照当物体贴近毛玻璃时，是可以隔着毛玻璃看清物体的轮廓的，具体的原理可以是当投影屏幕的另一侧的物体距离投影屏幕较远时，物体表面反射出的可见光(此时物体相当于光源)在传播了一定长度后才被散射，人眼很难根据散射后的可见光的逆传播方向确定光源位置，但是投影设备能够将可将光聚焦在投影屏幕处，这就等效于投影设备将作为光源的投影图像放在了投影屏幕处，当等效出的投影图像的可见光在开始传播的地方就被散射，即使方向改变了，但投影图像的散射后的可见光的逆传播路径仍然可以聚焦于投影图像处，因此投影图像看起来并没有模糊，因此投影屏幕的散射对投影图像的呈现的影响很低。再者，由于投影屏幕的另一侧的光线很暗，因此投影图像的可见光的强度比物体的可见光强度要高许多，因此投影设备投射出的可见光在投影屏幕上形成的图像可见，然而投影屏幕后方的物体却不可见是可以实现的。
为了使得散射层11能够进行瑞利散射，散射层11可以包括直径位于瑞利散射直径范围内的散射颗粒，而位于瑞利散射直径范围可以使得散射颗粒 对可见光和不可见光均能够以瑞利散射的方式进行散射。
在具体实施过程中，散射层11所包括的散射颗粒可以采用特定的工艺以等间隔或不等间隔的方式填充于透明的基底材料内部，或者，散射颗粒也可以涂覆于透明基底材料的表面，另外，散射颗粒可以是不透明的颗粒，这样以保证散射层11对光的散射作用，本发明实施例对于散射颗粒设置于投影屏幕1中的具体形式和散颗粒的材质不做具体限制，只要能满足投影屏幕1对于投影设备1所投射的可见光和对于深度采集设备3所投射的不可见光均具有瑞利散射的特性即可。
进一步地，根据瑞利散射的特性可知，可以采用直径远小于入射光波长的散射颗粒作为散射层11中的散射介质，并且为了使得能够对波长最小的蓝色可见光也可以进行瑞利散射，所以可以以蓝色可见光的波长(即475nm)为基准来确定散射颗粒的直径，即确定瑞利散射直径范围，例如可以采用直径小于30nm的散射颗粒组成散射层11，即瑞利散射直径范围为(0，30nm]，可替换的，考虑到散射颗粒在散射层11中能够均匀填充，或者还可以将瑞利散射直径范围设置为[20nm，30nm]，可替换的，还可以采用直径均为28nm的散射颗粒组成散射层11，等等。
请参见图3，图3为本发明实施例中采用直径为28nm的散射颗粒组成的散射层11对光进行散射的散射强度与波长的对应关系，其中，横坐标表示波长，纵坐标表示散射强度，可见，随着波长的增加，散射强度呈较大幅度减小的趋势，而在1065nm处，散射强度接近于0，此时散射层13对于1065nm的红外光具有近似透明的特性，这样可以使得深度采集设备3发射的红外光能够完整且以较大强度透过投影屏幕1以投射到投影屏幕1前方的物体上，以便深度采集设备3能够尽量准确地采集到物体的深度信息。
当采用具有图3所示散射特性的散射层11之后，投影屏幕1可以为红外光提供近似透明的特性，这样可以尽量保证深度信息采集的准确性，但是，由于散射强度随波长增加呈较大幅度的减弱，并且投影设备2所投影的三种可见光的波长也是不相同的，所以对于均由投影设备2投射的三种可见光的 散射强度之间的差距也较大，这样将可能导致在进行投影时三基色的散射差别过大，例如当蓝色可见光的散射强度过大而红色可见光的散射强度较低时，整个投影画面将会呈现蓝色(即冷色)调，影响投影图像的投影质量。
基于此，为了提高投影图像的质量，以使得在投影时能够尽量呈现正常的彩色图像，进一步地，本发明实施例可以在散射层11包括的瑞利散射直径范围的散射颗粒的基础上进行掺杂，通过掺杂后的散射颗粒进行等离子体共振效应以增强散射层11对特定波长的光线的散射强度，这样可以增强对散射强度较低的可见光(例如红色可见光或绿色可加光)的散射强度，以尽量减小几种可见光的散射强度之间的差距，降低差异化显示。
其中，等离子体共振效应，或者称为表面等离子共振(Surface Plasmon Resonance，SPR)，是一种物理现象，当入射光以临界角入射到两种不同折射率的介质界面时，可引起金属自由电子的共振，由于共振致使电子吸收了光能量，从而使反射光在一定角度内大大减弱，而散射作用增强，从而可以增强对光的散射强度。
为了便于理解，以下对可能的掺杂方式进行举例介绍。
可选的，在具有瑞利散射直径范围的散射颗粒的基础上，掺入红光平衡直径范围内的红光共振颗粒。
可替换的，在具有瑞利散射直径范围的散射颗粒的基础上，掺入绿光平衡直径范围内的绿光共振颗粒。
可替换的，在具有瑞利散射直径范围的散射颗粒的基础上，同时掺入红光平衡直径范围内的红光共振颗粒和绿光平衡直径范围内的绿光共振颗粒。
其中，红光共振颗粒可以在红色可见光下产生等离子体共振效应，以增强对红色可见光的散射强度，以使得散射层11对红色可见光的散射强度与散射层11对蓝色可见光的散射强度之间的差值小于预设的红光平衡散射强度。
绿光共振颗粒可以在绿色可见光下产生等离子体共振效应，以增强对绿色可见光的散射强度，以使得散射层11对绿色可见光的散射强度与散射层11对蓝色可见光的散射强度之间的差值小于预设的绿光平衡散射强度。
当同时掺杂有红光共振颗粒和绿光共振颗粒时，可以使得散射层11对蓝色可见光、绿色可见光和红色可见光其中的任意两种可见光的散射强度之间的差值均小于预设的平衡散射强度。
由于三种可见光中的蓝色可见光的波长最短，在进行瑞利散射时的散射强度是最大的，所以可以以蓝色可见光的散射强度为基准，通过掺入第红光平衡直径范围的红光共振颗粒以增强对红色可见光的散射强度，或者通过掺入绿光平衡直径范围的绿光共振颗粒以增强对绿色可见光的散射强度，或者可以同时掺入红光共振颗粒和绿光共振颗粒以同时增强对红色可见光和绿色可见光的散射强度以尽量分别减小红色可见光和绿色可见光与蓝色可见光之间的散射强度的差距，通过降低散射差异来减弱三基色在进行显示的差异，进而提升投影质量。
进一步地，在散射层11同时掺杂有直径位于红光平衡直径范围内的红光共振颗粒和位于绿光平衡直径范围内的绿光共振颗粒时，可以分别通过红光共振颗粒和绿光共振颗粒的等离子体共振效应以分别增强散射层11对红色可见光和绿色可见光的散射强度，以使得散射层11对蓝色可见光、绿色可见光和红色可见光其中的任意两种可见光的散射强度之间的差值均小于预设的平衡散射强度，也就是说，通过本发明实施例中的掺杂方式，可以较大程度上减小三种可见光两两之间的散射强度的差距，以尽量减弱三基色在进行显示的差异，提升投影质量。
其中，预设的红光平衡散射强度和预设的绿光平衡散射强度可以相同，例如均为0.05，或者也可以不同，例如预设的红光平衡散射强度为0.05，预设的绿光平衡散射强度为0.03。
继续以上述例子为例，预设的平衡散射强度可以与预设的红光平衡散射强度相等，即为0.05，或者也可以与预设的绿光平衡散射强度相等，即为0.03，或者也可以为其它值，例如为0.02，也就是说，预设的平衡散射强度与预设的绿光平衡散射强度和预设的红光平衡散射强度可以相同或不同。假设，散射层11对于蓝色可见光、绿色可见光和红色可见光的散射强度分别是x，y， z，那么可以要求x-y、x-z和y-z三者的值均小于预设的平衡散射强度，这样可以尽量减少三基色光之间的散射强度的差距，以尽量提高投影的质量。
假设在进行掺杂之前，散射层11对蓝色可见光、绿色可见光和红色可见光的散射强度分别是0.98、0.9和0.82，而在同时掺入红光共振颗粒和绿光共振颗粒之后，散射层11对蓝色可见光、绿色可见光和红色可见光的散射强度分别是0.98、0.95和0.94，可见，通过掺杂之后，散射层11对绿色可见光和对红色可见光的散射强度都有所增加了。
另外，由于三种可见光中红色可见光的波长最大，所以在未掺杂前采用瑞利散射的散射层11对红色可见光的散射强度最低，即红色可见光与蓝色可见光之间的散射强度的差距要大于绿色可见光与蓝色可见光之间的散射强度的差距，所以可选的，为了尽量减小三基色之间的散射强度的差距，在进行掺杂时可以尽量增强对于红色可见光的散射强度。
在具体实施过程中，红光平衡直径范围的红光共振颗粒例如可以包括二氧化硅纳米金壳等，这些颗粒可以在700nm的波长下进行共振，以增强红色可见光的散射强度。其中，本发明实施例中的二氧化硅纳米金壳可以呈中空壳体状，其外径为80nm左右，而内径为20cm左右，即为厚度为60nm左右的中空壳体。
绿光平衡直径范围的绿共振颗粒例如可以包括直径为80～100nm的黄金纳米球等，这些颗粒可以在550nm的波长下进行共振，以增强绿色可见光的散射强度。
当然，红光平衡直径范围的红光共振颗粒和绿光平衡直径范围的绿光共振颗粒包括但不限于以上列举的两种，只要能用于在红色可见光下进行共振以增强红色可见光的散射强度的散射颗粒均可以作为红光平衡直径范围的红光共振颗粒，以及只要能用于在绿色可见光下进行共振以增强绿色可见光的散射强度的共振颗粒均可以作为绿光平衡直径范围的绿光共振颗粒，本发明实施例不做限制。
另外，当将包括散射层11的投影屏幕1应用于图1或图2中所示的投影 系统中而用于呈现图像时，为了避免投影屏幕1的投影图像在各像素之间产生串扰而影响投影屏幕1的投影质量，本发明实施例中，可以将散射层11的厚度d设置为小于第一长度，具体来说，第一长度为投影屏幕1的投影像素的水平长度和垂直长度中的较小者，即第一长度为投影图像中的单个像素的水平长度和垂直长度中的最小长度。
其中，第一长度可以根据图1或图2中所示的投影设备2的投影分辨率和投影设备2能够投影的最小投影尺寸确定，即可以根据投影设备2的投影分辨率和投影设备2能够投影的最小投影尺寸确定散射层11的厚度d。
假设，投影设备2的投影分辨率为Dx×Dy，投影设备2的最小投影尺寸为Wmin×Hmin，那么投影屏幕1的投影像素的水平长度＝Wmin/Dx，而投影屏幕1的投影像素的垂直长度＝Hmin/Dy，那么，第一长度即为Wmin/Dx和Hmin/Dy中的较小者。
其中，Dx和Dy分别表示投影设备2的投影分辨率的横向分辨率和纵向分辨率，例如为1024像素×768像素，Wmin和Hmin分别表示投影设备2的最小投影尺寸的宽度和高度，例如也可以以像素表示，例如为256像素×192像素。
在本发明实施例中，通过投影屏幕1在投影图像时的单个像素，可以确定散射层11的厚度，这样可以尽量避免投影屏幕1在投影图像时的各像素之间产生串扰，进而可以提升投影屏幕1的投影质量，以提升这个投影系统的性能。
在实际中，在通过图1或图2中的投影系统对投影屏幕1前方场景中的物体进行深度信息采集时，或许只希望采集场景中的部分物体或其中一个物体的深度信息，例如以远程视频会议的场景来说，例如只希望采集场景中的发言者的深度信息，但是深度采集设备3一般是向整个覆盖范围投射不可见光，例如对于会议室中的桌椅和花盆等物体均投射了不可见光，这样就可能造成资源浪费。
基于此，请参见图4，本发明实施例的投影系统还可以包括空间光调制器4，空间光调制器4可以与深度采集设备3连接，空间光调制器4设置于深度 采集设备3和投影屏幕1之间，其用于将深度采集设备3所发射的不可见光投射到指定的投射区域，即投射到需要采集深度信息的物体所在的区域。
也就是说，可以先确定需要投射不可见光的区域，即先确定“指定的区域”，例如将“指定的区域”称作感兴趣区域，再通过空间光调制器4对深度采集设备3所发射的不可见光进行空间调制，以将不可见光分区域投射，这样就无需每次都通过深度采集设备3投射较大范围的不可见光，以尽量降低不可见光的浪费，提高不可见光的利用效率，减少资源浪费。
在具体调制的过程中，例如可以将通过深度采集设备3所投射的全部光的能量集中起来后再向指定的区域进行分区投射，那么向指定的区域所投射的不可见光的能量与调制之前的能量相等，相当于是，通过空间光调制器4的调制作用，投射的光的总能量不变，通过能量的重新分配以尽量提高深度信息采集的准确性。
或者例如，通过空间光调制器4的调制之后，向指定的区域所投射的不可见光的能量与调制之前是不变的，这样可以尽量节约资源，避免浪费。
通过空间光调制器4对不可见光进行调制后分区投射之前，需要先确定感兴趣区域，例如图4所示，可以将场景中的两名与会人员所在的区域确定为感兴趣区域。在具体实施过程中，例如可以采用手动设置的方式确定感兴趣区域，或者，投影系统也可以采用图像识别的方式自动确定感兴趣区域，等等。
如图5A所示，矩形框50所表示的区域为投影屏幕1前方场景的全部区域，而场景中有3个与会人员，则可以将这3个与会人员所在的区域确定为感兴趣区域，具体来说，由于3个与会人员相邻，则可以如图5A中所示，将3个与会人员所连通的区域(即矩形框51所表示的区域)确定为感兴趣区域，或者，为了尽量提高不可见光的利用率，还可以将3个与会人员分别所在的区域均确定为感兴趣区域，即确定三个感兴趣区域，如图5B所示。
在确定出感兴趣区域之后，可以通过预定算法计算感兴趣区域的全息图，例如采用迭代傅立叶变换法(Iterative Fourier transform algorithm，IFTA)或 单像素翻转法(Single pixel flipping algorithms)，等等。进一步地，在获得感兴趣区域的全息图之后，可以生成对应的控制信号并发送给空间光调制器4，当空间光调制器4在接收该控制信号之后，便可以对深度采集设备3发射的不可见光进行重新分配以投射到预先确定的感兴趣区域。
请参见图6，本发明实施例提供一种屏幕60，屏幕60的一侧覆盖有散射层11，即屏幕60中包括散射层11，用于对来自屏幕60的一侧的可见光进行瑞利散射，使得位于屏幕60的另一侧的用户看不到位于屏幕60的一侧的物体，也就是说，在本发明实施例中，通过散射层11对来自于屏幕60的一侧的可见光的散射作用，可以使得屏幕60对位于屏幕60的另一侧的用户的视线具有遮挡作用。
本发明实施例中的屏幕60可以应用于图1-图4中任一所示的背投系统中，也就是说，可以用本发明实施例中的屏幕60代替图1-图6中任一所示的背投系统中的投影屏幕1。
屏幕60中的散射层11对可见光的散射强度大于散射层11对不可见光的散射强度，可选的，不可见光的波长大于可见光的波长，例如，可见光例如可以包括三基色光，即包括蓝色可加光、绿色可见光和红色可见光，不可见光包括红外光或远红外光，等等，例如散射层11对蓝色可见光、绿色可见光和红色可见光的散射强度分别是0.98、0.93和0.89，而对红外光的散射强度是0.11。
由于投影设备一般是以蓝色可加光、绿色可见光和红色可见光进行投影，所以当以较高的散射强度对可见光进行散射时，可以使得蓝色可加光、绿色可见光和红色可见光均投射到屏幕60上而无法到达用户的眼睛，即此时屏幕60对于用户来说相当于是实体阻挡的，这样可以在保证较好的投影质量以满足用户的投影需求的前提下，又可以尽量避免用户看到屏幕60后方放置的物体，使得观影效果更加，进而提升用户的观影感受。
而由于深度采集设备一般通过红外光进行深度信息的采集，所以当以较低的散射强度对红外光进行散射时，屏幕60对于来自屏幕60的一侧的红外 光具有近似透明或完全透明的特性，那么此时红外光可以直接透过屏幕60而投射到屏幕60的另一侧以实现对屏幕60的另一侧的物体的深度信息的准确采集，满足用户对深度信息采集的需求。
进一步地，请参见图7，屏幕60还包括第一面71和第二面72，散射层11位于第一面71和第二面72之间，且假设散射层11的厚度为d。屏幕60可以通过第二面72将投影的图像提供给观看者，即可以通过第二面72呈现图像，也就是说，可以将第二面72作为屏幕60的投影正面，当用户位于屏幕60的前方时，可以通过第二面72上光线的反射作用看到第二面72上的投影图像。
可选的，屏幕60的第一面71和第二面72可以包括对光具有透射作用的透射膜，即第一面71和第二面72对本发明实施例中的可见光和不可见光均具有透射特性，第一面71和第二面72对于本发明实施例中的可见光和不可见光来说相当于是透明的。另外，为了对屏幕60起到支撑作用，第一面71和第二面72还可以包括其它能够起到支撑作用的结构，只需保证对于可见光和不可见光能够进行透射即可，另外第一面71和第二面72可以具有一定厚度，例如可以是具有一定厚度的透射膜，等等。
本发明实施例中的屏幕60的其它相关介绍可以参见图1-图4中所述的投影系统中的投影屏幕1的介绍，此处就不再重复。
以上实施例仅用以对本申请的技术方案进行了详细介绍，但以上实施例的说明只是用于帮助理解本发明的方法及其核心思想，不应理解为对本发明的限制。本技术领域的技术人员在本发明揭露的技术范围内，可轻易想到的变化或替换，都应涵盖在本发明的保护范围之内。

Claims (13)

  1. 一种背投系统，其特征在于，所述背投系统包括：
    包括散射层的投影屏幕，用于呈现图像；
    投影设备，用于向所述投影屏幕投射可见光，以使得所述投影屏幕呈现图像；
    深度采集设备，与所述投影设备位于所述投影屏幕的同一侧，用于通过所述投影屏幕向位于所述投影屏幕的另一侧的对象投射不可见光，以及接收所述对象对所述不可见光进行反射的反射光，进而获得所述对象的深度信息，所述不可见光的波长大于可见光的波长；
    所述散射层，用于对来自所述一侧的可见光和所述不可见光进行瑞利散射，所述散射层对可见光的散射强度大于所述散射层对所述不可见光的散射强度。
  2. 如权利要求1所述的背投系统，其特征在于，所述散射层包括直径位于瑞利散射直径范围内的散射颗粒，使得所述散射颗粒对可见光以及所述不可见光以瑞利散射的方式进行散射。
  3. 如权利要求1或2所述的背投系统，其特征在于，所述投影设备投射的可见光包括蓝色可见光和红色可见光；所述散射层还包括直径位于红光平衡直径范围内的红光共振颗粒；
    其中，所述红光共振颗粒在所述红色可见光下产生等离子体共振效应以增强对所述红色可见光的散射强度，使得所述散射层对所述红色可见光的散射强度与所述散射层对所述蓝色可见光的散射强度之间的差值小于预设的红光平衡散射强度。
  4. 如权利要求1或2所述的背投系统，其特征在于，所述投影设备投射的可见光包括蓝色可见光和绿色可见光；所述散射层还包括直径位于绿光平衡直径范围内的绿光共振颗粒；
    其中，所述绿光共振颗粒在所述绿色可见光下产生等离子体共振效应以 增强对所述绿色可见光的散射强度，使得所述散射层对所述绿色可见光的散射强度与所述散射层对所述蓝色可见光的散射强度之间的差值小于预设的绿光平衡散射强度。
  5. 如权利要求1或2所述的背投系统，其特征在于，所述投影设备投射的可见光包括蓝色可见光、绿色可见光和红色可见光；所述散射层还包括直径位于绿光平衡直径范围内的绿光共振颗粒和位于红光平衡直径范围内的红光共振颗粒；
    其中，所述红光共振颗粒在所述红色可见光下产生等离子体共振效应以增强对所述红色可见光的散射强度，所述绿光共振颗粒在所述绿色可见光下产生等离子体共振效应以增强对所述绿色可见光的散射强度，以使得所述散射层对所述蓝色可见光、所述绿色可见光和所述红色可见光其中的任意两种可见光的散射强度之间的差值均小于预设的平衡散射强度。
  6. 如权利要求1-5任一项权利要求所述的背投系统，其特征在于，所述投影屏幕用于在所述背投系统中呈现图像，所述散射层的厚度小于所述投影屏幕所呈现的图像中单个像素的水平长度和垂直长度中的最小长度。
  7. 如权利要求1-6任一项权利要求所述的背投系统，其特征在于，所述背投系统还包括：
    空间光调制器，设置于所述深度采集设备和所述投影屏幕之间，用于调制所述不可见光，使得所述不可见光投射到指定的区域。
  8. 一种屏幕，其特征在于，所述屏幕的一侧覆盖有散射层；
    所述散射层，用于对来自所述屏幕的所述一侧的可见光进行瑞利散射；
    其中，所述散射层对所述可见光的散射强度大于所述散射层对不可见光的散射强度，所述不可见光的波长大于所述可见光的波长。
  9. 如权利要求8所述的屏幕，其特征在于，所述散射层包括直径位于瑞利散射直径范围内的散射颗粒，使得所述散射颗粒对可见光以及所述不可见光以瑞利散射的方式进行散射。
  10. 如权利要求8或9所述的屏幕，其特征在于，所述可见光包括蓝色 可见光和红色可见光；所述散射层还包括直径位于红光平衡直径范围内的红光共振颗粒；
    其中，所述红光共振颗粒在所述红色可见光下产生等离子体共振效应以增强对所述红色可见光的散射强度，使得所述散射层对所述红色可见光的散射强度与所述散射层对所述蓝色可见光的散射强度之间的差值小于预设的红光平衡散射强度。
  11. 如权利要求8或9所述的屏幕，其特征在于，所述投影设备投射的可见光包括蓝色可见光和绿色可见光；所述散射层还包括直径位于绿光平衡直径范围内的绿光共振颗粒；
    其中，所述绿光共振颗粒在所述绿色可见光下产生等离子体共振效应以增强对所述绿色可见光的散射强度，使得所述散射层对所述绿色可见光的散射强度与所述散射层对所述蓝色可见光的散射强度之间的差值小于预设的绿光平衡散射强度。
  12. 如权利要求8或9所述的屏幕，其特征在于，所述投影设备投射的可见光包括蓝色可见光、绿色可见光和红色可见光；所述散射层还包括直径位于绿光平衡直径范围内的绿光共振颗粒和位于红光平衡直径范围内的红光共振颗粒；
    其中，所述红光共振颗粒在所述红色可见光下产生等离子体共振效应以增强对所述红色可见光的散射强度，所述绿光共振颗粒在所述绿色可见光下产生等离子体共振效应以增强对所述绿色可见光的散射强度，以使得所述散射层对所述蓝色可见光、所述绿色可见光和所述红色可见光其中的任意两种可见光的散射强度之间的差值均小于预设的平衡散射强度。
  13. 如权利要求8-12任一项权利要求所述的屏幕，其特征在于，所述屏幕用于在背投系统中呈现图像，所述散射层的厚度小于所述图像中单个像素的水平长度和垂直长度中的最小长度。
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