Display device and method for displaying image

Abstract

The invention discloses a display device and a method for displaying an image, and relates to the technical field of optical display, and the display device comprises an optical engine which is used for forming a plurality of input light beams which correspond to image points of a virtual image; an expansion panel for diffractively expanding the input light beam received from the optical engine to form an output light beam; a display panel for forming a second image on a display surface of the display panel; the user interface is used for receiving user input; and a control unit for controlling the formation of the first input light beam and the formation of the second image in accordance with a user input received through the user interface, in which the display panel is located between the expansion panel and the viewing area, the display panel being transparent to allow the output light beam to propagate from the expansion panel through the display panel to the viewing area. According to the display device and the method for displaying the image, the pressure of eyes when the display device is used can be relieved.

Description

Technical Field

[0001] The present application relates to the field of optical display technology, and in particular to a display device and a method for displaying an image. Background Art

[0002] The lens of the human eye is surrounded by ciliary muscles, which control the focal length of the eye. Focusing the eye at close distances requires the ciliary muscles to contract to shorten the focal length of the lens. In this case, viewing images displayed on the smaller touch screens on traditional mobile phones may cause stress on the eyes. Some scientific studies have even shown that prolonged viewing of close objects may increase the probability of myopia (i.e., nearsightedness). Summary of the invention

[0003] The purpose of the present application is to provide a display device and a method for displaying images, which have multiple display modes, thereby reducing eye pressure when using the display device.

[0004] The scope of protection sought by various embodiments of the present invention is defined by the independent claims. Any embodiments described in this specification that are not within the scope of the independent claims should be interpreted as examples for understanding various embodiments of the present invention.

[0005] The display device can be set to display at least two different types of images, i.e., a virtual image and a surface image. Both types of images can represent, for example, video still images, graphics and / or text. In addition, the display device can optionally include data processing capabilities and / or communication capabilities. The display device can be, for example, a portable handheld device with data processing capabilities and communication capabilities. The display device can be, for example, a smart phone.

[0006] The display device includes an optical engine for forming input light. The input light includes a plurality of input light beams representing input image points. The direction of each input light beam may correspond to the position of the input image point, and the intensity of each input light beam may correspond to the brightness of the image point. The direction of each input light beam corresponds to the angular position of the image point of the virtual image, and the intensity of the input light beam corresponds to the brightness of the image point of the virtual image.

[0007] The display device includes a diffractive expansion panel that forms a plurality of output beams by diffracting and expanding an input beam. When the output beams are emitted into the eyes of an observer, the observer can see a displayed virtual image. Each point of the virtual image is represented by a collimated output beam, so the virtual image appears to be displayed at a great distance from the eyes.

[0008] The display device may have at least one display mode that allows the eye to view images with relaxed ciliary muscles, even if the distance between the display device and the eye is small, for example less than 0.5 meters. The display device may have, for example, a virtual display mode, in which the display device is arranged to display virtual images at a long distance. The displayed virtual images may be viewed with relaxed ciliary muscles. The display device may be suitable for viewing the displayed virtual images for a long time without requiring pressure on the ciliary muscles.

[0009] The display device also includes a transparent display panel for displaying a surface image. The surface image is formed on a display surface of the display panel. The display panel may be, for example, a liquid crystal display (LCD panel). The display panel may be, for example, a transparent LED panel. The display device has at least one display mode in which an image is formed on the display panel so that the distance between the displayed image and the eye is approximately equal to the distance between the display device and the eye, for example, less than 0.5 meters. The display device may have, for example, a surface display mode in which the display device is arranged to display a surface image on the display panel. Displaying a surface image may facilitate, for example, providing user input via a touch panel of the display device, because the visual elements of the displayed surface image have a determined lateral position relative to the touch panel.

[0010] When the eye is located within the viewing area of ​​the display device, the displayed virtual image and surface image can be observed. The viewing area can also be referred to as, for example, the viewing pupil or eye box.

[0011] The transparent display panel may be located between the extension panel and the viewing area. The display device may include a stack, which in turn includes at least an extension panel and a transparent display panel. For visible output light projected from the extension panel through the display panel, the optical attenuation of the display panel may be, for example, less than 80%, less than 50% or even less than 20%. The normal direction is perpendicular to the plane of the extension panel. The corresponding transmittance of the extension panel may be, for example, greater than 20%, greater than 50% or even greater than 80% for the visible light. The display panel includes display pixels. The display pixels and the material layers of the display panel may attenuate the transmitted light to a certain extent, but the attenuation may be limited by selecting the size of the display pixels and / or the material of the material layers.

[0012] The display panel may, for example, cover more than 50% of the area of ​​the diffractive outcoupling element of the extension panel. The viewing area of ​​the display device may be smaller than the sum of the viewing area of ​​the extension panel and the viewing area of ​​the display panel. The viewing area of ​​the extension panel may, for example, be greater than 70% of the front area of ​​the display device, and the viewing area of ​​the display panel may also, for example, be greater than 70% of the front area of ​​the display device.

[0013] In one embodiment, the display panel and the expansion panel can be, for example, located in the same housing, so that the viewing area of ​​the expansion panel can be, for example, greater than 70% of the housing front area, and the viewing area of ​​the display panel can also be, for example, greater than 70% of the housing front area. The transparency of the display panel can allow these panels to be accommodated in the same housing without increasing the housing front area.

[0014] The control unit of the device may be arranged to change the display mode, for example based on user input received via a user interface of the device. The device may comprise, for example, a touch panel, and the control unit may be arranged to change the display mode according to a gesture detected by the touch panel.

[0015] In one embodiment, the virtual display mode can be used as the default operation mode of the device to reduce eye strain. The control unit of the device can temporarily change the operation mode from the virtual display mode to the surface display mode, for example, when receiving user input through the touch panel, and the control unit can automatically change the operation mode from the surface display mode back to the virtual display mode after receiving the user input.

[0016] Long-term operation in the surface display mode may cause stress to the eyes. The user may wish to limit the usage time in the surface display mode to reduce the stress on the ciliary muscles. In one embodiment, if the operation time in the surface display mode exceeds a predetermined limit, the device can be arranged to provide a prompt to the user. For example, if the cumulative operation time in the surface display mode exceeds a predetermined number of hours per day, the device can be arranged to provide a prompt to the user. The prompt may also be referred to as, for example, a warning or an alarm.

[0017] The display device may optionally include a controllable shutter panel, which may be located between the extension panel and the display panel. The shutter panel may control the propagation of light from the display panel to the viewing area. The state of the shutter panel may be changed from a transparent state to a light blocking state to provide a dark background for the virtual image, thereby improving the visibility of the displayed virtual image. The shutter panel may be configured to allow or prevent light from propagating from the display panel to the viewing area. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1a A side view of a display device in a composite display mode provided by an embodiment of the present application;

[0020] Figure 1b A side view of a display device in a surface display mode provided by an embodiment of the present application;

[0021] Figure 1c A side view of a display device in a virtual display mode provided by an embodiment of the present application;

[0022] Figure 1d A shutter panel provided in an embodiment of the present application provides a side view of a dark background for a virtual image;

[0023] Figure 1e A shutter panel provided in an embodiment of the present application provides a side view of a dark background for a surface image;

[0024] Figure 1f A controllable shutter area of ​​a shutter panel provided in an embodiment of the present application provides a side view of a dark background for a surface image;

[0025] Figure 2a A state diagram of a display device provided in an embodiment of the present application working in a surface display mode;

[0026] Figure 2b A state diagram of a display device provided in an embodiment of the present application working in a composite display mode;

[0027] Figure 2c A state diagram of a display device provided in an embodiment of the present application working in a virtual display mode;

[0028] Figure 3a A schematic diagram of a display device receiving user input through a touch panel provided in an embodiment of the present application;

[0029] Figure 3b A flow chart of a method for a display device to receive user input provided by an embodiment of the present application;

[0030] Figure 4a A schematic diagram of the structure of an optical engine provided in an embodiment of the present application;

[0031] Figure 4b A schematic diagram of the structure of an extension panel provided in an embodiment of the present application;

[0032] Figure 4c A schematic diagram of the structure of a display panel provided in an embodiment of the present application;

[0033] Figure 4d A schematic diagram of the structure of a shutter panel provided in an embodiment of the present application;

[0034] Figure 5A schematic diagram of the dimensions of various components in the display device provided in an embodiment of the present application;

[0035] Figure 6a A schematic diagram of an extended panel provided in an embodiment of the present application that forms an output light beam by diffracting and expanding an input light beam;

[0036] Figure 6b A schematic diagram of the dimensions of the expansion panel provided in an embodiment of the present application;

[0037] Figure 6c A schematic diagram of waveguide light propagating in a transparent substrate of an extension panel provided in an embodiment of the present application;

[0038] Figure 7a-7e The input light beam provided for the implementation of the present application corresponds to an image point on the microdisplay that forms an input image;

[0039] Figure 7f An extended output beam of a virtual image point provided by an embodiment of the present application;

[0040] Figure 7g A top view of the angular width of a virtual image provided by an embodiment of the present application;

[0041] Figure 7h A side view of the angular height of a virtual image provided by an embodiment of the present application;

[0042] Figure 8 A schematic diagram of a display panel provided in an embodiment of the present application.

[0043] Icons: 500-display device; LCD1-display panel; EPE1-extension panel; STC1-stack; ENG1-optical engine; IMG0-input image; P0 P1 P2 P3 P4-image point; IN1-input light; B0-input beam; VIMG1-virtual image; OUT1-first output light; B3-output beam; EYE1-eye of observer; BOX1-viewing area; DSRF-display surface; IMG2-second image; zVIMG-position of virtual image VIMG1; zLCD-position of second image IMG2; zEYE-position of eye EYE1; CNT1-control unit; TOU1-touch panel; MEM1-memory 1; DATA1-image data; MEM2-memory 2; PROG1-program code; UIF1-user interface; COM 1-user input; RXTX1-communication unit; SENG-control signal; SLCD-control signal; STOU-touch panel signal; HOU1-housing; BCK1-background layer; SHU1-shutter panel; SREG1-first shutter area; SREG2-second shutter area; SUB1-substrate; DOE1-coupling element; DOE2-intermediate element; DOE3-coupling element; SRF1-first main surface; SRF2-second main surface; LS1-backlight panel; POL1-first polarizer; E1-first electrode layer; LIQ1-liquid crystal layer; E2-second electrode; POL2-second polarizer. DETAILED DESCRIPTION

[0044] Reference Figure 1a , the display device 500 may include an extension panel EPE1 and a display panel LCD1. The display device 500 may include a stack STC1 of the panels EPE1 and LCD1.

[0045] The display device 500 may include an optical engine ENG1. The optical engine ENG1 may form an input image IMG0 on the micro display DISP0 and may collimate light from image points P0 P1 P2 P3 P4 of the input image IMG0 to form an input light IN1 ( Figure 7a-7e ). The input light IN1 includes a plurality of collimated input light beams B0 propagating in different directions with different intensities. The input light IN1 may represent an input image IMG0 and a corresponding virtual image VIMG1.

[0046] The display device 500 can display a virtual image VIMG1 by forming a first output light OUT1. The extension panel EPE1 can form the first output light OUT1 by diffracting and expanding the input light IN1. The first output light OUT1 includes a plurality of output light beams B3 ( Figure 7f). When the observer's eye EYE1 is located in the viewing area BOX1 of the display device 500 and when the output light OUT1 enters the eye EYE1, the eye EYE1 can see the displayed virtual image VIMG1. The viewing area BOX1 can also be called, for example, an eye box. The viewing area BOX1 refers to the entire angular width and the entire angular height within the space in which the eye EYE1 can be positioned to view the displayed virtual image VIMG1.

[0047] The direction of each output light beam B3 corresponds to the position of an image point of the virtual image VIMG1 , and the intensity of the output light beam B3 corresponds to the brightness of the image point.

[0048] Each image point of the virtual image VIMG1 may correspond to a substantially collimated output beam, so the eye EYE1 sees the virtual image VIMG1 as being located far away from the eye EYE1. The perceived distance LVIMG between the virtual image VIMG1 and the eye EYE1 may be greater than 2 meters, for example. The perceived distance LVIMG may even be infinite.

[0049] The display panel LCD1 may be arranged to form the second image IMG2 on its own planar display surface DSRF. The display panel LCD1 may be, for example, a transparent liquid crystal display ( Figure 8 ). The display panel LCD1 may be, for example, a transparent LED display comprising a two-dimensional array of light emitting diodes. The display panel LCD1 may comprise a two-dimensional array of individually controllable display pixels arranged in rows and columns. The two-dimensional array of display pixels may define a display surface DSRF. The number of rows may be, for example, between 200 and 20,000, and the number of columns may be, for example, between 200 and 20,000.

[0050] The distance LEYE between the second image IMG2 and the eye EYE1 may be substantially equal to the distance between the display device 500 and the eye EYE1. The distance LEYE may be, for example, between 0.1 m and 0.5 m. The eye EYE1 needs to adapt to this distance LEYE when focusing on the second image IMG2.

[0051] The display panel LCD1 may form a second image IMG2 on a display surface DSRF of the display panel LCD1. A distance between the display surface DSRF and the eye EYE1 may be equal to a distance between the second image IMG2 and the eye EYE1.

[0052] zVIMG may represent the position of the virtual image VIMG1. zLCD may represent the position of the second image IMG2. zEYE may represent the position of the eye EYE1. For example, the position zLCD of the second image IMG2 may be selected as a reference position (zLCD=0).

[0053] The display device 500 may further include a control unit CNT1 for controlling the operation of the display device 500 .

[0054] The display device 500 may further include a transparent touch panel TOU1 for receiving user input by detecting gestures. The touch panel TOU1 may be located on the display panel LCD1.

[0055] The display device 500 may further include a memory MEM1 for storing image data DATA1. The image data DATA1 may include one or more digital images. The image data DATA1 may include a video. The display device 500 may be arranged to form a virtual image VIMG1 and / or a second image IMG2 according to the image data DATA1.

[0056] The display device 500 may further include a memory MEM2 for storing the computer program code PROG1. The control unit CNT1 may control the operation of the display device 500 by executing the computer program code PROG1.

[0057] The display device 500 may include a user interface for receiving user input. The touch panel TOU1 may be arranged to operate as a first user interface. In addition to the touch panel TOU1, the display device 500 may also include an additional user interface UIF1. The user input COM1 may be received by the touch panel TOU1 and / or by the additional user interface UIF1. The user interface UIF1 may include, for example, one or more buttons, a keyboard, a mouse, an acceleration sensor and / or a gravity sensor. For example, the user may also provide user input by changing the direction of the display device 500 and / or shaking the display device 500. The display device 500 may also include a user interface UIF1 instead of the touch panel TOU1.

[0058] The display device 500 may further include a communication unit RXTX1 for receiving and / or sending data. The communication unit RXTX1 may, for example, communicate image data DATA1 and / or program data PROG1. The communication unit RXTX1 may, for example, communicate with the Internet and / or a local area network. The communication unit RXTX1 may communicate via wireless and / or wired communication. The communication unit RXTX1 may communicate via a mobile communication network and / or Bluetooth (trademark).

[0059] The control unit CNT1 may form a control signal SENG for controlling the operation of the optical engine ENG1. The control signal SENG may include, for example, image data DATA1.

[0060] The control unit CNT1 may form a control signal SLCD for controlling the operation of the display panel LCD1. The control signal SLCD may include, for example, image data DATA1.

[0061] The transparent touch panel TOU1 may form a touch panel signal STOU. The touch panel signal STOU may indicate a detected gesture. The touch panel signal STOU may indicate a received user input COM1. The touch panel TOU1 may be, for example, a capacitive, resistive, optical and / or ultrasonic touch panel.

[0062] The distance (in the SZ direction) between the display panel LCD1 and the touch panel TOU1 may be so small that the detected finger position may be associated with the display element position of the surface image IMG2. Displaying the surface image IMG2 may facilitate receiving the user input COM1 through the touch panel TOU1. The display panel LCD1 and the touch panel TOU1 may be arranged together to operate as a touch screen. The symbol LTOU may represent the distance in the SZ direction between the surface image IMG2 and the outer surface of the touch panel TOU1. The distance LTOU may be, for example, less than 2 mm, less than 1 mm, less than 0.5 mm, or even less than 0.2 mm.

[0063] The display device 500 may have different display modes MODE0, MODE1, MODE2. The display device 500 may have a composite display mode MODE0, in which the virtual image VIMG1 and the surface image IMG2 are displayed simultaneously. The display device 500 may have a virtual display mode MODE1, in which only the virtual image VIMG1 is displayed. The display device 500 may have a surface display mode MODE2, in which only the surface image IMG2 is displayed. The display device 500 may control the display modes MODE0, MODE1, MODE2 according to a user input COM1. The user input COM1 may be received, for example, via a touch panel TOU1 and / or via a user interface UIF1.

[0064] In one embodiment, the expansion panel EPE1, the optical engine ENG1, the display panel LCD1, the touch panel TOU1 and the control unit CNT1 are located in the same housing HOU1 of the display device 500 ( Figure 5 ).

[0065] In addition to the extended panel EPE1 and the display panel LCD1, the stack STC1 may also include a background layer BCK1 ( Figure 1d )、Shutter panel SHU1( Figure 1e ) and / or touch panel TOU1.

[0066] SX, SY, SZ may denote orthogonal directions. The extension panel EPE1 may be parallel to the plane defined by the directions SX and SY. The direction SZ may be perpendicular to the extension panel EPE1.

[0067] Figure 1b An operation in the surface display mode MODE2 is shown. The second image IMG2 may be formed on the surface DSRF within the display panel LCD1. The second image IMG2 may also be referred to as, for example, a surface image or a real image.

[0068] Figure 1c The operation in the virtual display mode MODE1 is shown, in which only the virtual image VIMG1 is displayed.

[0069] The display panel LCD1 may be transparent, so that the output light OUT1 projected from the diffractive outcoupling element of the extension panel may be transmitted to the viewing area BOX1 through the display panel LCD1.

[0070] For visible output light projected from the extension panel through the display panel, the optical attenuation of the display panel may be, for example, less than 80%, less than 50% or even less than 20%. The normal direction is perpendicular to the plane of the extension panel. The corresponding transmittance of the extension panel may be, for example, greater than 20%, greater than 50% or even greater than 80% for the visible light. The display panel includes a two-dimensional array of display pixels. The display pixels and the material layers of the display panel may attenuate the transmitted light to a certain extent, but the attenuation may be limited by selecting the size of the display pixels and / or the material of the material layers.

[0071] Reference Figure 1d The display device 500 may further include a background layer BCK1 to prevent the ambient light AMB0 from propagating through the extended panel EPE1. The background layer BCK1 may improve the visual contrast of the displayed virtual image VIMG1. The background layer BCK1 may also improve the visual contrast of the displayed surface image IMG2.

[0072] Reference Figure 1e The display device 500 may optionally include a shutter panel SHU1 that can be controlled to enable or disable the propagation of the output light OUT1 from the extension panel EPE1 to the viewing area BOX1. The shutter panel SHU1 can improve the visual contrast of the display surface image IMG2 by providing a controllable dark background for the display panel LCD1.

[0073] The control unit CNT1 may form a control signal SSHU for controlling the operation of the shutter panel SHU1. The shutter panel SHU1 may be implemented, for example, by using a controllable liquid crystal layer.

[0074] Reference Figure 1f, the shutter panel SHU1 may include one or more individually controllable shutter regions SREG1, SREG2. For example, the first shutter region SREG1 may be temporarily set to a transmission state to allow the output light OUT1 to propagate from the extension panel EPE1 to the viewing area BOX1. For example, the second shutter region SREG2 may be temporarily set to a light blocking state to prevent the output light OUT1 from propagating from the extension panel EPE1 to the viewing area BOX1.

[0075] Therefore, the first shutter region SREG1 (in the transmission state) can allow viewing of the displayed virtual image VIMG1, while the second shutter region SREG2 (in the light blocking state) can provide a controllable dark background for a portion of the display panel LCD1, and the second shutter region SREG2 (in the light blocking state) can also temporarily reduce the height and / or width of the viewing area BOX1.

[0076] Reference Figure 2a , the display device 500 may be arranged to operate in a surface display mode MODE2. The display panel LCD1 may form a second output light OUT2 representing a displayed surface image IMG2. The distance between the displayed surface image IMG2 and the eye EYE1 may be substantially equal to the distance between the display device 500 and the eye EYE1. The surface image IMG2 may include, for example, graphics, such as photos and / or characters. The surface image IMG2 may include, for example, characters ABC. The surface image IMG2 may also be, for example, a video image displayed using the display panel LCD1.

[0077] Reference Figure 2b , the display device 500 can be arranged to operate in the composite display mode MODE0. The eye EYE1 can simultaneously receive the first output light OUT1 from the extension panel EPE1 and the second output light OUT2 from the display panel LCD1. The first output light OUT1 can be transmitted from the extension panel EPE1 to the viewing area BOX1 through the display panel LCD1. The first output light OUT1 can include an output light beam representing the displayed virtual image VIMG1. The second output light OUT2 can represent the displayed surface image IMG2.

[0078] One or more controllable shutter regions SREG2 of the shutter panel SHU1 may be selectively set in a light-blocking state to improve the visual contrast of one or more regions of the surface image IMG2 displayed on the display panel LCD1. Setting a controllable shutter region (e.g., SREG2) to a light-blocking state may reduce the height and / or width of the viewing area BOX1. In other words, setting a controllable shutter region (e.g., SREG2) to a light-blocking state may reduce the size of the spatial region of the entire angular width and the entire angular height of the displayed virtual image VIMG1 that the eye EYE1 can see.

[0079] Reference Figure 2c , the display device 500 may be arranged to operate in a virtual display mode MODE1. The extension panel EPE1 may form a first output light by diffraction expansion of the input light received from the optical engine ENG1. The first output light OUT1 includes an output light beam representing an image point of the displayed virtual image VIMG1.

[0080] The virtual image VIMG1 may include, for example, graphics, such as photos and / or characters. The virtual image VIMG1 may include, for example, characters FGH. The virtual image VIMG1 may also be, for example, a video image displayed using the expansion device EPE1.

[0081] Reference Figure 3a , the display device 500 may include a touch panel TOU1 for detecting gestures. The touch panel TOU1 may receive a user input (COM1) by detecting the positions of one or more fingers of a hand HAND1 of the user.

[0082] The display device 500 may be arranged to display a surface image IMG2 in a surface display mode MODE2 or a mixed display mode MODE0. The surface image IMG2 displayed on the display panel LCD1 may include one or more input elements E0, E1, E2. A user may provide a user input COM1 by touching one or more input elements E0, E1, E2. A user may select one or more options, for example, by touching one or more input elements E0, E1, E2.

[0083] In one embodiment, the display device 500 can set a display mode (MODE0, MODE1, MODE2) according to a user input (COM1) received through the touch panel TOU1.

[0084] Figure 3bThe method steps for setting the display mode are shown exemplarily. Setting the display mode may start at step 1010. The display device 500 may check whether the touch panel TOU1 is touched at step 1020. If there is no touch panel, the method may restart at step 1010. If the touch panel TOU1 is touched at step 1020, the display device 500 may start to operate in the surface display mode MODE2 (or the composite display mode MODE0) at step 1030. At step 1040, the display device 500 may display one or more input elements E0, E1, E2 as part of the display surface image IMG2. The user may select a display mode by touching a displayed input element E0, E1, E2. At step 1050, the touch screen TOU1 may receive the user input COM1 by detecting the finger position of the user's hand HAND1. The display device 500 may set the display mode (MODE0, MODE1, MODE2) according to the user input COM1 at step 1060. At step 1070, the display device 500 may run one or more applications in the selected display mode. When running the application, the display device 500 may display one or more images. When the application is run in the selected display mode, the display device 500 can display a video. During the running of the application or after the running of the application is stopped, the selection of the display mode can be restarted in step 1010.

[0085] The control unit CNT1 of the display device 500 may be configured to perform method steps 1010, 1020, 1030, 1040, 1050, 1060, 1070 by executing the computer program code PROG1. The control unit CNT1 may perform these steps together with the functional units TOU1, LCD1, ENG1, for example.

[0086] In one embodiment, the display device 500 may be arranged to start temporary operation in the surface display mode MODE2 (or the composite display mode MODE0) also when the display device 500 is shaken. The user interface UIF1 may include, for example, an acceleration sensor for detecting that the display device 500 is shaken.

[0087] Reference Figure 4a, the optical engine ENG1 forms an input light IN1, and the input light IN1 includes a plurality of input light beams B0. The input light beams B0 may propagate in different directions, corresponding to image points of the input image IMG0. The intensity of the input light beam B0 may correspond to the brightness of the image points of the input image IMG0. The extension panel EPE1 may display a virtual image VIMG1 by diffracting and expanding the input light beam B0, so that the displayed virtual image VIMG1 may correspond to the input image IMG0. The optical engine ENG1 may include, for example, a microdisplay DISP0 and a collimating optical element LNS0. The microdisplay DISP0 may display the input image IMG0. The collimating optical element LNS0 may form a collimated input light beam B0 by collimating light of image pixels of the input image IMG0. The center of the microdisplay DISP0 and the center of the collimating optical element LNS0 may jointly define an optical axis AX0 of the optical engine ENG1.

[0088] The input image IMG0 may represent information for display. The input image IMG0 may represent, for example, graphics and / or text. The input image IMG0 may represent, for example, a video. The engine ENG1 may be arranged to generate a static image and / or a video. The engine ENG1 may generate a real input image IMG0 from a digital image. The engine ENG1 may receive one or more digital images from, for example, an Internet server or a smartphone.

[0089] The display DISP0 may include a two-dimensional display pixel array. The display DISP0 may include a two-dimensional light-emitting display pixel array. The engine ENG1 may include, for example, one or more light-emitting diodes (LEDs). The display DISP0 may also be referred to as, for example, a microdisplay. The display DISP0 may also be referred to as, for example, a spatial intensity modulator. The input image IMG0 may also be referred to as, for example, a main image.

[0090] The input image IMG0 may be a monochrome image or a multi-color image. The input image IMG0 may be, for example, an RGB image including a red (R) partial image, a green (G) partial image, and a blue (B) partial image. The input image IMG0 may be formed by modulating a laser or by modulating light obtained from one or more light emitting diodes.

[0091] The display DISP0 may include, for example, one or more microdisplay imagers, such as liquid crystal on silicon (LCOS), a liquid crystal display (LCD), a digital micromirror device (DMD). The display DISP0 may generate an input image IMG0 with a resolution of 1280×720 (HD). The display DISP0 may generate an input image IMG0 with a resolution of 1920×1080 (full HD). The display DISP0 may generate an input image IMG0 with a resolution of 3840×2160 (4K ultra HD). The input image IMG0 may include multiple image points P0, P1, P2, etc. The optical engine ENG1 may include a collimating optical element LNS1 to form a light beam for each image pixel. The optical engine ENG1 may include a collimating optical element LNS1 to form a substantially collimated light beam from the light of the image point.

[0092] Reference Figure 4b The extended panel EPE1 may include a group of diffraction elements GRP1 implemented on a waveguide substrate SUB1, including diffraction coupling elements DOE1, DOE2, and DOE3. The diffraction element group GRP1 may include a diffraction coupling element DOE1, which forms a waveguide light by diffracting the input light IN1. The input light IN1 can be received from the optical engine ENG1. The waveguide light can propagate in one or more lateral directions (SX, SY) within the substrate SUB1. The waveguide light can be confined within the substrate SUB1 by total internal reflection (TIR). The extended panel EPE1 may include a coupling element DOE3, which forms an output light OUT1 from the substrate SUB1 by diffracting the waveguide light.

[0093] The extended panel EPE1 may comprise a set of diffractive elements GRP1 which contribute to the direction of the output light beam.

[0094] The diffraction element group GRP1 may include only two elements, namely, an in-coupling element DOE1 and an out-coupling element DOE3. The in-coupling element DOE1 may form a first waveguide light by diffracting the input light IN1. The first waveguide light may be waveguided in the substrate SUB1. The out-coupling element DOE3 may form an output light OUT1 by diffracting the first waveguide light from the substrate SUB1.

[0095] The diffraction element group GRP1 may further include at least one intermediate element DOE2. The coupling-in element DOE1 may form a first waveguide light by diffracting the input light IN1. The intermediate element DOE2 may form an extended waveguide light by diffracting the first waveguide light. The coupling-out element DOE3 may form an output light OUT1 by diffracting the extended waveguide light from the substrate SUB1. The first waveguide light and the extended waveguide light may be waveguided in the substrate SUB1.

[0096] However, the diffractive element group GRP1 may comprise two or more intermediate diffractive elements, which may be operated in parallel or in series. In one embodiment, the extended panel EPE1 may comprise four diffractive elements, which contribute to the direction of the output light beam.

[0097] For example, the coupling element DOE1 can form a first waveguide light by diffracting the input light IN1. The first intermediate element can form a second waveguide light from the first waveguide light, and the second intermediate element can form a third waveguide light from the second waveguide light. The coupling element DOE3 can form an output light OUT1 by diffracting the third waveguide light from the substrate SUB1.

[0098] The outcoupling element DOE3 may have a width w3 and a height h3. The dimensions w3 and h3 of the outcoupling element DOE3 may also define the maximum lateral dimension of the output light OUT1. The dimensions w3 and h3 of the outcoupling element DOE3 may also define the maximum lateral dimension of the viewing area BOX1.

[0099] Figure 4c The display panel LCD1 is shown. The active display area of ​​the display panel LCD1 may have a width wLCD and a height hLCD.

[0100] Figure 4d The shutter panel SHU1 is shown. The width of the shutter panel SHU1 may be, for example, greater than or equal to the width wLCD of the display panel LCD1. The height of the shutter panel SHU1 may be, for example, greater than or equal to the height hLCD of the display panel LCD1.

[0101] The shutter panel SHU1 may include one or more individually controllable shutter regions SREG1, SREG2. The area of ​​the first shutter region SREG1 may be smaller than the area of ​​the display panel LCD1. The area of ​​the second shutter region SREG2 may be smaller than the area of ​​the display panel LCD1. The height of the first shutter region SREG1 may be hSREG1. The height of the second shutter region SREG2 may be hSREG2. The height hSREG1 and / or hSREG2 may, for example, be smaller than the height hLCD of the display panel LCD1.

[0102] Reference Figure 5 , the extension panel EPE1 may partially or completely cover the display panel LCD1. The outcoupling element DOE3 of the extension panel EPE1 may partially or completely cover the effective display area of ​​the display panel LCD1.

[0103] The display device 500 may include a housing HOU1. The display panel LCD1 and the extension panel EPE1 may be disposed in the housing HOU1. The housing HOU1 may have a width wHOU in the direction SX and a height hHOU in the direction SY.

[0104] The effective display area of ​​the display panel LCD1 may, for example, cover at least 50% of the area of ​​the out-coupling element DOE3. The out-coupling element DOE3 may, for example, cover at least 50% of the effective display area of ​​the display panel LCD1.

[0105] The width wLCD of the display panel LCD1 may be, for example, greater than or equal to 70% of the width wHOU of the housing HOU1. The height hLCD of the display panel LCD1 may be, for example, greater than or equal to 70% of the height hHOU of the housing HOU1. The width w3 of the outcoupling element DOE3 may be, for example, greater than or equal to 70% of the width wHOU of the housing HOU1. The height h3 of the outcoupling element DOE3 may be, for example, greater than or equal to 70% of the height hHOU of the housing HOU1.

[0106] The display device 500 may be, for example, a portable smartphone. The display device 500 may be, for example, a portable tablet computer. The width wHOU of the housing HOU1 may be, for example, between 50 mm and 200 mm, wherein the height hHOU may be, for example, between 100% and 300% of the width wHOU. Alternatively, the height hHOU may be, for example, between 50 mm and 200 mm, wherein the width wHOU may be, for example, between 100% and 300% of the height hHOU. In one embodiment, the device may be used in portrait mode and landscape mode by rotating it 90 degrees.

[0107] from Figure 6a It can be seen that the expander panel EPE1 can form the output light OUT1 by diffraction expansion of the input light IN1. The width wOUT1 of the output light OUT1 may be larger than the width wIN1 of the input light IN1. The expander panel EPE1 may also be called a diffraction beam expander or an exit pupil expander. The input light IN1 may come from the optical engine ENG1. The input light IN1 may include a plurality of substantially collimated input light beams B0, which correspond to image points of the input image IMG0. The output light OUT1 may include a plurality of substantially collimated output light beams B3, which correspond to image points of the displayed virtual image VIMG1. The virtual image VIMG1 may correspond to the input image IMG0.

[0108] The expander panel EPE1 may include a group of diffraction elements GRP1 implemented on a waveguide substrate SUB1. The expansion panel EPE1 may include a diffraction coupling element DOE1, an intermediate element DOE2 and an output coupling element DOE3. The coupling element DOE1 forms a first waveguide light B1 by diffracting the input light IN1. The intermediate element DOE2 forms a second waveguide light B2 by diffracting the first waveguide light. The output coupling element DOE3 forms an output light OUT1 by diffracting the second waveguide light B2. The light beam B3 of the output light OUT1 represents the image point of the virtual image VIMG1. When the output light beam B3 is irradiated to the eye EYE1, the eye EYE1 can see the displayed virtual image VIMG1.

[0109] Figure 6b The dimensions of the extension panel EPE1 are shown by way of example.

[0110] The diffractive coupling element DOE1 has a width w1 and a height h1. The coupling element DOE1 comprises a diffraction grating G1. The coupling element DOE1 has diffraction features F1, such as microscopic grooves. The coupling element DOE1 has a grating period d1. The coupling element DOE1 has a grating vector V1. The direction of the grating vector V1 can be specified by an angle β1 with a reference direction (e.g. SX).

[0111] The diffractive intermediate element DOE2 has a width w2 and a height h2. The element DOE2 comprises a diffraction grating G2. The element DOE2 has diffractive features F2, such as microscopic grooves. The element DOE2 has a grating period d2. The element DOE2 has a grating vector V2. The direction of the grating vector V2 can be specified by an angle β2 with a reference direction.

[0112] The diffractive out-coupling element DOE3 has a width w3 and a height h3. The out-coupling element DOE3 comprises a diffraction grating G3. The out-coupling element DOE3 has diffraction features F3, such as grooves under a microscope. The out-coupling element DOE3 has a grating period d3. The out-coupling element DOE3 has a grating vector V3. The direction of the grating vector V3 can be specified by an angle β3 with a reference direction.

[0113] The size of the grating vector depends on the grating period of the diffraction grating of the diffraction element, and the direction of the grating vector depends on the orientation of the diffraction grating. For example, the size of the grating vector V1 depends on the grating period d1 of the diffraction grating G1 of the diffraction element DOE1, and the direction β1 of the grating vector V1 depends on the orientation of the diffraction feature F1 of the diffraction grating G1.

[0114] The extended panel EPE1 includes a plurality of diffraction elements DOE1, DOE2 and DOE3 in the optical path. The coupling-in element DOE1 can receive input light beams B0P1, B0P2 through the first main surface SRF1 of the extended panel EPE1. The extended panel EPE1 can be designed to make the vector sum of the grating vectors of the diffraction elements in the optical path zero (V1+V2+V3=0) to ensure that each output light beam B3aP1, B3aP2 provided by the coupling-out element DOE3a is parallel to the corresponding input light beam B0P1, B0P2 obtained from the optical engine ENG1.

[0115] The diffraction elements DOE1, DOE2, DOE3 can be produced by photolithography. For example, one or more imprinting tools can be produced by electron beam lithography, and the diffraction gratings of the diffraction elements can be formed by using the one or more imprinting tools. A replica of the diffraction microstructure of the imprinting tool can be formed on the waveguide plate SUB1, for example, by using the imprinting tool as a mold or by pressing the surface of the waveguide plate with the imprinting tool.

[0116] Reference Figure 6c , the waveguide substrate SUB1 of the extension panel EPE1 has a first main surface SRF1 and a second main surface SRF2. The first main surface SRF1 may be parallel to the second main surface SRF2. tSUB1 may represent a distance between the first main surface SRF1 and the second main surface SRF2.

[0117] The waveguide light may propagate in the substrate SUB1 by total internal reflection (TIR). The waveguide light (eg, B2) may be repeatedly reflected at the first main surface SRF1 and the second main surface SRF2 until the waveguide light (B2) is coupled out of the substrate.

[0118] In particular, the collimated input light beam B0P2 may represent an image point P2 of the input image IMG0. The waveguide light B2P2 may be formed by diffracting the light of the input light beam B0P2. The collimated output light beam B3P2 may be formed by diffracting the light B2P2 out of the substrate SUB1. The output light beam B3P2 may represent an image point P2 of the displayed virtual image VIMG1.

[0119] The extended panel EPE1 comprises a waveguide substrate SUB1. The diffractive elements DOE1, DOE2, DOE3 may be implemented on the waveguide plate SUB1. The waveguide plate SUB1 comprises a planar waveguide core. In one embodiment, the plate SUB1 may optionally comprise, for example, one or more cladding layers, one or more protective layers and / or one or more mechanical support layers. The thickness tSUB1 may refer to the thickness of the planar waveguide core of the plate SUB1.

[0120] The substrate SUB1 may have a refractive index n1. The refractive index n1 may, for example, be in the range of 1.5 to 1.9. The waveguide plate SUB1 may contain or essentially consist of a transparent solid material. The plate SUB1 may, for example, contain glass, polycarbonate or polymethyl methacrylate (PMMA). The diffractive optical elements may, for example, be formed by molding, embossing and / or etching. The diffractive optical elements may, for example, be implemented by one or more surface diffraction gratings. In particular, the diffractive optical elements of the extended panel EPE1 may be surface diffraction gratings, which may be implemented on the same main surface (SRF1 or SRF2) of the waveguide plate SUB1. Forming the elements on the same main surface may simplify production.

[0121] Figures 7a to 7e It is shown how collimated input light beams B0P0, B0P1, B0P2, B0P3, B0P4 are formed by collimating light from image points P0, P1, P2, P3, P4 of the input image IMG0. The input light IN1 received from the optical engine ENG1 may include multiple input light beams B0P0, B0P1, B0P2, B0P3, B0P4. Point P0 may be the center point of the image IMG0. Points P1, P2, P3, P4 may be corner points of the image IMG0.

[0122] Reference Figure 7f The extension panel EPE1 may form an output beam B3P0 by diffracting and expanding the light of the input beam B0P0. The output beam B3P0 may represent the image point P0 of the input image IMG0 and the image point P0 of the virtual image VIMG1.

[0123] The input image IMG0 may include a center point P0 and four corner points P1, P2, P3, and P4. P1 may represent the upper left corner point. P2 may represent the upper right corner point. P3 may represent the lower left corner point. P4 may represent the lower right corner point. The input image IMG0 may include, for example, graphic characters "F", "G", and "H". The input image IMG0 may represent displayed information.

[0124] The extended panel EPE1 can form output beams B3P1, B3P2, B3P3, B3P4 by diffracting the light of the expanded input beams B0P1, B0P2, B0P3, B0P4. The output beams B3P1, B3P2, B3P3, B3P4 can represent the image points P1, P2, P3, P4 of the input image IMG0 and the image points P1, P2, P3, P4 of the virtual image VIMG1.

[0125] The display device 500 may include:

[0126] An optical engine ENG1 for forming an input light IN1, wherein the input light IN1 includes a plurality of input light beams B0P0, B0P1, B0P2, B0P3, B0P4, representing an input image IMG0 and a corresponding virtual image VIMG1;

[0127] The extended panel EPE1 is used for expanding the input light IN1 by diffraction to form the output light OUT1, wherein the output light OUT1 comprises a plurality of output light beams B3P0, B3P1, B3P2, B3P3, B3P4, representing the input image IMG0 and the corresponding virtual image VIMG1.

[0128] In one embodiment, the extended panel EPE1 can form an output beam B3P0 from an input beam P0P0, so that the output beam B3P0 is parallel to the input beam P0P0. The output beam B3P1 can be formed from the input beam P0P1, so that the output beam B3P1 is parallel to the input beam P0P1. The output beam B3P2 can be formed from the input beam P0P2, so that the output beam B3P2 is parallel to the input beam P0P2. The output beam B3P3 can be formed from the input beam P0P3, so that the output beam B3P3 is parallel to the input beam P0P3. The output beam B3P4 can be formed from the input beam P0P4, so that the output beam B3P4 is parallel to the input beam P0P4.

[0129] Reference Figure 7g and Figure 7h , the virtual image VIMG1 may have an angular width ΔφVIMG and an angular height ΔθVIMG. The direction of each beam may be specified by an azimuth angle (e.g., φB3P1) and an elevation angle (e.g., θB3P1). REF1 may represent a reference plane defined by directions SY and SZ. REF2 may represent a reference plane defined by directions SX and SZ.

[0130] Reference Figure 8, the transparent display panel LCD1 may be, for example, a liquid crystal display. The display panel LCD1 may include, for example, a backlight panel LS1, a first polarizer POL1, a first electrode layer E1, a liquid crystal layer LIQ1, a second electrode E2, and a second polarizer POL2. The backlight panel LS1 may provide a backlight BL1. The first polarizer POL1 may polarize the backlight BL1. At least one of the electrode layers E1 and E2 includes an array of individually controllable electrodes. The liquid crystal orientation of different pixels in the liquid crystal layer LIQ1 may be controlled by an electric field generated between the electrode layers E1 and E2. The liquid crystal may change the polarization state of the backlight BL1 according to its orientation. The liquid crystal layer LIQ1 may form a modulated light ML1 by adjusting the polarization of the backlight BL1. The second polarizer POL2 may allow or prevent the modulated light ML1 from passing through the second polarizer POL2 according to the polarization state of the modulated light ML1. Therefore, the display panel LCD1 may form a surface image IMG2 on the display panel LCD1. Dark pixels of the image IMG2 may be formed at positions where the second polarizer POL2 prevents the modulated light ML1 from propagating. Bright pixels of the image IMG2 may be formed at positions where the second polarizer POL2 allows the modulated light ML1 to propagate. The display panel LCD1 may optionally include a color filter array RGB1 for displaying a multicolor image IMG2. The multicolor image IMG2 may be, for example, an RGB image. The RGB image includes a red sub-image, a green sub-image and a blue sub-image.

[0131] For those skilled in the art, modifications and variations of the apparatus and method according to the present invention are foreseeable. These illustrations are schematic. The above-mentioned specific embodiments are described with reference to the accompanying drawings for illustrative purposes only and are not meant to limit the scope of the present invention, which is defined by the appended claims.

Claims

1. A display device, characterized in that: An optical engine (ENG1) for forming a plurality of input light beams (B0), wherein the plurality of input light beams (B0) respectively correspond to image points (P0, P1, P2, P3, P4) of a virtual image (VIMG1); an expansion panel (EPE1) for expanding an input beam (B0) received from an optical engine (ENG1) by diffraction to form an output beam (B3); A display panel (LCD1) for forming a second image (IMG2) on a display surface (DSRF) of the display panel (LCD1); a user interface (TOU1, UIF1) for receiving a user input (COM1); and a control unit (CNT1) for controlling the formation of the input light beam (B0) and controlling the formation of the second image (IMG2); wherein the display device (500) is arranged to form a virtual image (VIMG1) and a second image (IMG2) such that the virtual image (VIMG1) and the second image (IMG2) can be seen from an observation area (BOX1) of the display device (500), wherein the display panel (LCD1) is located between the extension panel (EPE1) and the observation area (BOX1), wherein the display panel (LCD1) is transparent to allow an output light beam (B3) to propagate from the extension panel (EPE1) through the display panel (LCD1) to the observation area (BOX1).

2. The display device according to claim 1, characterized in that The display panel (LCD1) causes attenuation to the output light (OUT1) projected from the extension panel (EPE1), wherein the display panel (LCD1) is arranged such that the attenuation caused by the display panel (LCD1) is less than 50%.

3. The display device according to claim 2, characterized in that The extended panel (EPE1) covers at least 50% of the active display area of ​​the display panel (LCD1).

4. The display device according to claim 1, characterized in that There is a virtual display mode (MODE1), wherein a virtual image (VIMG1) is observable in the virtual display mode (MODE1), and a second image (IMG2) is not observable in the virtual display mode (MODE1).

5. The display device according to claim 1, characterized in that There is a surface display mode (MODE2), wherein the second image (IMG2) is observable in the surface display mode (MODE2), and the virtual image (VIMG1) is not observable in the surface display mode (MODE2).

6. The display device according to claim 1, characterized in that There is a composite display mode (MODE0), wherein the virtual image (VIMG1) and the second image (IMG2) are simultaneously observable in the composite display mode (MODE0).

7. The display device according to any one of claims 4 to 6, characterized in that: The control unit (CNT1) is arranged to set a display mode (MODE0, MODE1, MODE2) of the display device (500) according to a user input (COM1) received through a user interface (TOU1, UIF1).

8. The display device according to claim 1, characterized in that The display device (500) includes a transparent touch panel (TOU1) for receiving user input (COM1).

9. The display device according to claim 8, characterized in that Arranged to display one or more input elements (E) on a display panel (LCD1) and receive user input (COM1) via a touch panel (TOU1).

10. The display device according to claim 1, characterized in that The optical engine (ENG1) includes a micro display (DISP0) for forming an input image (IMG0), and a collimating optical device (LNS0) for forming an input light beam by collimating pixel light of the input image (IMG0).

11. The display device according to claim 1, characterized in that The display device (500) is a portable handheld device.

12. The display device according to claim 1, characterized in that A shutter panel (SHU1) is included between an extension panel (EPE1) and a display panel (LCD1), wherein the shutter panel (SHU1) includes at least one controllable shutter region (SREG2) for controlling the propagation of an output light beam from the extension panel (EPE1) to an observation region (BOX1).

13. The display device according to claim 1, characterized in that A background layer (BCK1) is included to prevent ambient light (AMB0) from propagating to a viewing area (BOX1) through an extension panel (EPE1), wherein the extension panel (EPE1) is located between the background layer (BCK1) and a display panel (LCD1).

14. A method for displaying an image using a display device according to any one of claims 1 to 13, characterized in that: include: Displaying a virtual image (VIMG1) by forming an expanded output beam (B3) from an input beam (B0) received from an optical engine (ENG1) using an expansion panel (EPE1); displaying a second image (IMG2) on the display panel (LCD1), as well as, The display of the virtual image (VIMG1) and the display of the second image (IMG2) are controlled according to a user input (COM1) received through the user interface (UIF1).

Images