Patent Publication Number: US-11641458-B2

Title: Autostereoscopic devices and methods for producing 3D images

Description:
RELATED APPLICATIONS 
     This application claims priority to U.S. Provisional Patent Application No. 62/948,926 filed on Dec. 17, 2019, which is incorporated by reference in its entirety, along with all other patents and patent applications disclosed herein. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to the field of 3D image devices, more specifically autostereoscopic devices that include parallax barriers. 
     BACKGROUND OF THE INVENTION 
     An autostereoscopic device is able to produce a 3D image without the need for special glasses. Some autostereoscopic devices include parallax barriers. A conventional parallax barrier includes a layer having a fixed pattern of light barriers and slits or pinholes. The parallax barrier is placed in front of and spaced apart from a second layer, an image-forming layer, which provides image specific information. The parallax barrier selectively blocks light emitted or modulated by the second layer such that the left and right eyes of a suitably positioned observer see a 3D image. Conventional fixed parallax barriers have several disadvantages including a narrow viewing angle and a dark image resulting from absorption of light by the light barriers. 
     A content-adaptive autostereoscopic device also comprises at least two, spaced-apart layers. However, the parallax barrier layer does not have a fixed pattern, but rather a light-transmissive, non-binary image that can be varied according to the content to be produced. Essentially, a light-transmissive independently controllable device is used as the parallax barrier and a second independently controllable device forms the rear layer. The combination of two variable layers allows a wider viewing angle and a brighter image than those that are possible with a fixed parallax barrier. This, however, comes at the cost of a significantly more complex device requiring a controller that is able to coordinate the images produced by the first and second layers. In addition, multiple layers of imaging media and electrode layers impairs the transparency of the parallax barrier layer. 
     Autostereoscopic devices incorporating a conventional parallax barrier are produced from at least two separately printed images, at least one of which is disposed on a substrate, that are subsequently joined together into registration with precision. Similarly, autostereoscopic devices having a content-adaptive parallax barrier are produced from two separate displays (e.g., LCD displays) that require precise registration to each other. 
     Thus, there is a need for improved 3D devices having parallax barriers. 
     SUMMARY OF THE INVENTION 
     Aspects of the present invention overcome the drawbacks of previous systems and methods by providing autostereoscopic devices and methods of generating images by using a single addressing unit, or two addressing units, to address two image-forming layers. 
     In one aspect, an autostereoscopic device for generating an autostereoscopic image is provided. The device comprises a substrate, a first image-forming layer disposed on the substrate, a second image-forming layer, a light-transmissive layer positioned between the first image-forming layer and the second image-forming layer, and an addressing unit comprising a heating element. The first and second image-forming layers comprise a first and second material, respectively, having a thermally adjustable optical property. The addressing unit is configured to apply heat to the first image-forming layer and the second image-forming layer. The first image-forming layer and the second image-forming layer generate an autostereoscopic image. 
     In another aspect, an autostereoscopic device for generating an autostereoscopic image is provided that comprises a substrate, a first image-forming layer disposed on the substrate, a second image-forming layer, a light-transmissive layer positioned between the first image-forming layer and the second image-forming layer, a first addressing unit comprising a first heating element and a second addressing unit comprising a second heating element. The first and second image-forming layers comprise a first and second material, respectively, having a thermally adjustable optical property. The first addressing unit is configured to apply heat to the first image-forming layer and the second addressing unit is configured to apply heat to the second image-forming layer. The first image-forming layer and the second image-forming layer generate an autostereoscopic image. 
     In another aspect, an autostereoscopic device is disclosed comprising a substrate comprising a plurality of electrodes, a first layer of microcapsules located on the substrate comprising a first dispersion of electrophoretic particles, a second layer of microcapsules comprising a second dispersion of electrophoretic particles, and a layer of light-transmissive microcapsules between the first and second layer. The light-transmissive microcapsules may consist essentially of a light-transmissive fluid. 
     In yet another aspect, a method of producing an autostereoscopic image is provided. The method comprises the steps of (a) providing an autostereoscopic device comprising a substrate, a first image-forming layer comprising a first material having thermally adjustable optical properties, the first image-forming layer disposed on the substrate, a second image-forming layer comprising a second material having thermally adjustable optical properties, a light-transmissive layer positioned between the first and second image-forming layers, and an addressing unit comprising a heating element; and (b) heating the first and second image-forming layers with the addressing unit, such that the first and second image-forming layers generate an autostereoscopic image. The method may further comprise the steps of (c) providing three-dimensional image data to a controller; (d) computing an image to be produced by the first and second image-forming layers; and (e) controlling the heat applied by the addressing unit to the first and second image-forming layers. The autostereoscopic device used for the method may further comprise a second addressing unit and the heating step may comprise heating the first image-forming layer with the addressing unit and heating the second image-forming layer with the second addressing unit. 
     In another aspect, a method of producing an autostereoscopic image is provided. The method comprises the steps of (a) providing an autostereoscopic device comprising a substrate having a plurality of electrodes, a first layer of microcapsules located on the substrate comprising a first dispersion of electrophoretic particles, a second layer of microcapsules comprising a second dispersion of electrophoretic particles, and a layer of light-transmissive microcapsules between the first and second layer; (b) providing a three-dimensional image data to a controller; (c) computing an image to be displayed by the first and second layers of microcapsules; and (d) controlling the plurality of electrodes, such that the plurality of electrodes apply an electric field to the first and second layers of microcapsules and the first and second layers of microcapsules generate the autostereoscopic image. The light-transmissive microcapsules of the autostereoscopic device used in the method may consist essentially of a light-transmissive fluid. 
     It is to be appreciated that the features described above can be combined in any number of various ways to describe devices or methods that incorporate features disclosed herein. 
     The foregoing advantages of the invention will appear in the detailed description, which follows. In the description, reference is made to the accompanying drawings, which illustrate preferred aspects. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a schematic side view of a device for generating an autostereoscopic image according to a first embodiment of the present invention. 
         FIGS.  2 A to  2 E  are schematic side views of a device for generating an autostereoscopic image according to a second embodiment of the present invention. 
     
    
    
     The invention may be embodied in several forms without departing from its spirit or essential characteristics. The scope of the invention is defined in the appended claims, rather than in the specific description preceding them. All aspects that fall within the meaning and range of equivalency of the claims are therefore intended to be embraced by the claims. 
     DETAILED DESCRIPTION 
     The invention will now be described more specifically with reference to the following aspects. It is to be noted that the following aspects are presented herein for purpose of illustration and description only. It is not intended to be exhaustive or to be limited to the precise form disclosed. 
     It is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. 
     As used herein, “consisting essentially of” means that the composition or component may include additional ingredients, but only if the additional ingredients do not materially alter the basic and novel characteristics of the claimed compositions or methods. 
     Furthermore, the disclosed subject matter may be implemented as a device, method, apparatus, or article of manufacture using standard programming and/or engineering techniques and/or programming to produce hardware, firmware, software, or any combination thereof to implement aspects detailed herein. 
     The various aspects of the invention will be described in connection with a device for producing an autostereoscopic image. The features and advantages that arise due to aspects of the invention are well suited to this purpose. Still, it should be appreciated that the various aspects of the invention can be applied to other applications and to achieve other objectives as well. 
     Referring now to the Figures, and more particularly  FIG.  1   , a device for generating an autostereoscopic image according to a first embodiment of the present invention is shown. The device  100  includes an imaging member  101  and an addressing unit  102 . The imaging member  101  includes a first image-forming layer  104  disposed on a substrate  110 , a second image-forming layer  108 , and a light-transmissive layer  106  disposed between the first image-forming layer  104  and the second image-forming layer  108 . The first image-forming layer  104  and the second image-forming layer  108  are preferably light-transmissive and colorless, but contain a material having a thermally adjustable optical property. As used herein, “light-transmissive” layer means that sufficient light is transmitted through the layer designated as light-transmissive to enable an observer, looking through that layer from one side, to observe the change in optical states of the layer or another material on an opposing side of the layer. The material having a thermally adjustable optical property in the first and second image-forming layers may absorb specific wavelengths of light as defined by a first absorption spectrum and a second absorption spectrum respectively. In some aspects of the invention, the first and second absorption spectra are the same, that is, identical wavelengths of light that can be absorbed. However, in other aspects, the first and second absorption spectra overlap, but are not identical. The thermally adjustable optical property of the first material transitions at a first temperature and the thermally adjustable optical property of the second material transitions at a second temperature. The first temperature may be greater than the second temperature. 
     An optional light-transmissive protective layer  112  may also be disposed on the first image-forming layer  104 . In yet another aspect, the substrate  110  may include a reflective sheet (not shown in  FIG.  1   ), if the imaging member  101  is intended to form a reflective device. Alternatively, the substrate  110  may be a release sheet that is subsequently removed, so that the imaging member  101  may be laminated onto a light emitting member (not shown in  FIG.  1   ) comprising a backlight for illuminating the image-forming layers and provide an emissive device. 
     The image-forming layers  104  and  108  are optically adjustable so that their respective absorption spectra can be altered when the addressing unit  102  is used to address the imaging member  101 . The addressing unit  102  is capable of addressing the first image-forming layer  104  and the second image-forming layer  108  substantially simultaneously, thereby providing an auto registered autostereoscopic device. As previously explained, the image-forming layers  104  and  108  are preferably light-transmissive and colorless; however, specific locations on the image-forming layers may be addressed individually so that the color, i.e. absorptive/reflective properties, of the specific locations is adjusted. This allows a unique image to be produced on each of the image-forming layers. When adjusted, either the first or second image-forming layers  104  and  108  may form a parallax barrier, while the other of the first and second image-forming layer  104  and  108  provides a rear image to be viewed through the parallax barrier, and together the optically adjusted first and second image-forming layers  104 ,  108  generate an autostereoscopic image. 
     In one aspect, a desired three-dimensional image is provided to a controller, which computes the images to be produced on the first and second image-forming layers to form the three-dimensional image. As used herein, the term “controller” may include one or more processors and memories and/or one or more programmable hardware elements and is intended to include any types of processors, CPUs, microcontrollers, digital signal processors, or other devices capable of executing software instructions. The controller communicates the images to be produced to the addressing unit  102 , which adjusts the first image-forming layer  104  and second image-forming layer  108  accordingly. In some aspects, the controller may be a component of the device  100 ; however, the computation of the images to be produced may also be done remotely and communicated to the device  100 . 
     In one non-limiting aspect of the invention, the first image-forming layer  104  and the second image-forming layer  108  are thermally sensitive. The application of heat to one location of the image-forming layers changes the optical property of the material within that location, such that its respective absorption spectrum is adjusted. The addressing unit  102  has a heating element for applying heat to the imaging member  101  and the light-transmissive layer  106  may be thermally insulating to control the transmission of heat through the imaging member  101 . Because the addressing unit  102  is in contact with only one surface of the imaging member  101 , the first image-forming layer  104  may be less sensitive to heat than the second image-forming layer  108 , so that a variation in the time and intensity of heat applied to the surface of the imaging member  101  enables the materials in the first image-forming layer  104  and second image-forming layer  108  to be optically adjusted independently. The degree of light transmissivity or color of the adjusted regions in the first and second image-forming layers  104 ,  108  may also be varied, thereby improving the viewing angle of the image produced by the device. 
     An example of a device comprising a single addressing unit able to individually adjust the first and second image-forming layers is disclosed, for example, in U.S. Pat. No. 7,408,563, the entire content of which is incorporated by reference herein. The device eliminates the extra step of precisely registering the first and second image-forming layers by providing for the substantially simultaneous formation of the parallax barrier and rear image from two pre-laminated image-forming layers. In another embodiment, the device may include a second addressing unit that is applied to an opposing surface of the imaging member, such that the first addressing unit adjusts the optical properties of the first image-forming layer and the second addressing unit adjusts the optical properties of the second image-forming layer. 
     A direct thermal imaging technique may be used to form an image by heating the corresponding image-forming layer, which may be initially colorless, by the addressing unit. In direct thermal imaging, there is no need for ink, toner, or thermal transfer ribbon. Rather, the chemistry required to form an image is present in the imaging member itself. A discussion of various direct thermal color imaging methods is provided in U.S. Pat. No. 6,801,233 B2, the entire content of which is incorporated by reference herein. In the method of the present invention, an imaging member having two or more image-forming layers is addressed by an addressing unit, which may be a thermal printing head, to provide a colored image. The image may comprise multiple colors. The imaging member may be addressed in more than one pass of the addressing unit, at least one pass being at a different speed from at least another pass. Optionally, the imaging member is preheated to a different extent in at least one pass than in at least another pass. The heating may be direct heating or indirect heating. Each image-forming layer can change color, e.g., from initially colorless to colored, where it is heated to a particular temperature referred to herein as its activating temperature. All the layers of the image member may be transparent before color formation. The image-forming layers may be addressed at least partially independently by variation of two adjustable parameters, namely, temperature and time. These parameters can be adjusted to obtain the desired results in any particular instance by selecting the temperature of the addressing unit (e.g. the thermal printing head) and the period of time during which heat is applied to the thermal imaging member. Thus, each color of a multicolor imaging member can be printed alone or in selectable proportion with the other colors. The temperature-time domain is divided into regions corresponding to the different colors that it is desired to obtain in the final image. The image-forming layers of the imaging member undergo a change in color to provide the desired image in the imaging member. The change in color may be from colorless to colored, from colored to colorless, or from one color to another. The term “image-forming layer” includes all such options. Each of the image-forming layers may be independently addressed by application of heat with a thermal printing head in contact with the topmost layer of the member. In imaging members with two image-forming layers, the activating temperature of the second image-forming layer (that is, the image-forming layer closest to the surface of the thermal imaging member) is greater than the activating temperature of the first image-forming layer. 
     Referring now to  FIGS.  2 A to  2 E , a second embodiment of a device according to the present invention is illustrated.  FIGS.  2 A to  2 E  illustrate an imaging member of a device for generating an autostereoscopic image. The imaging member comprises a first image-forming layer  204  and a second image-forming layer  208  separated by a light-transmissive layer  206 . A substrate  210  on which the first image-forming layer is located includes a plurality of electrodes for addressing the first and second image-forming layers  204  and  208 . 
     The first image-forming layer  204  and the second image-forming layer  208  preferably each comprise a plurality of light-transmissive microcapsules containing dispersions of electrophoretically responsive particles disposed in a carrier medium, such as a fluid. The electrophoretic particles in the first and second image-forming layers may or may not have the same absorption spectra and/or electrophoretic mobility. 
     Numerous patents and applications assigned to or in the names of the Massachusetts Institute of Technology (MIT) and E Ink Corporation describe various technologies used in encapsulated electrophoretic and other electro-optic media. The technologies described in the these patents and applications, the entire contents of which are incorporated by reference herein, include:
     (a) Electrophoretic particles, fluids and fluid additives; see for example U.S. Pat. Nos. 7,002,728; and 7,679,814;   (b) Capsules, binders and encapsulation processes; see for example U.S. Pat. Nos. 6,922,276; and 7,411,719;   (c) Microcell structures, wall materials, and methods of forming microcells; see for example U.S. Pat. Nos. 7,072,095; and 9,279,906;   (d) Methods for filling and sealing microcells; see for example U.S. Pat. Nos. 7,144,942; and 7,715,088;   (e) Films and sub-assemblies containing electro-optic materials; see for example U.S. Pat. Nos. 6,982,178; and 7,839,564;   (f) Backplanes, adhesive layers and other auxiliary layers and methods used in displays; see for example U.S. Pat. Nos. 7,116,318; and 7,535,624;   (g) Color formation and color adjustment; see for example U.S. Pat. Nos. 7,075,502; and 7,839,564;   (h) Methods for driving displays; see for example U.S. Pat. Nos. 7,012,600; and 7,453,445;   (i) Applications of displays; see for example U.S. Pat. Nos. 7,312,784; and 8,009,348; and   (j) Non-electrophoretic displays, as described in U.S. Pat. No. 6,241,921; and U.S. Patent Application Publication Nos. 2015/0277160; 2015/0005720; and 2016/0012710.   

     Encapsulated electrophoretic media comprise one or more types of charged pigment particles that move through the fluid under the influence of an electric field, forming an image. Encapsulated electrophoretic media may comprise numerous small capsules, each of which itself comprises a charged pigment particles in a fluid medium, and a capsule wall surrounding the internal phase. Typically, the capsules are themselves held within a polymeric binder to form a coherent layer positioned between two electrodes. Alternatively, the charged particles and the fluid may be retained within a plurality of sealed cavities formed within a carrier medium, typically a polymeric film, often referred to as microcells. 
     Although electrophoretic media are often opaque (since, for example, in many electrophoretic media, the particles substantially block transmission of visible light through the display) and operate in a reflective mode, many electrophoretic films can be made to operate in a so-called “shutter mode” in which one optical state is substantially opaque and one is light-transmissive. See, for example, U.S. Pat. Nos. 5,872,552; 6,130,774; 6,144,361; 6,172,798; 6,271,823; 6,225,971; and 6,184,856. Examples of the can operate in such a mode include dielectrophoretic displays, which are similar to electrophoretic displays but rely upon variations in electric field strength; see U.S. Pat. No. 4,418,346. 
     In order to provide the required distance between the first image-forming layer  204  and the second image-forming layer  208  (illustrated in  FIGS.  2 A to  2 E ), the light-transmissive layer  206  may comprise one or more rows of light-transmissive capsules consisting essentially of a light-transmissive fluid and not containing optically adjustable materials, such as electrophoretic particles, such that the optical properties of the light-transmissive layer  206  remain substantially constant during operation of the device. Display devices formed by applying successive rows of encapsulated electrophoretic media and methods of driving the devices are disclosed, for example, in U.S. Pat. No. 8,576,476, the entire content of which is incorporated by reference herein. 
     The plurality of electrodes  211   a  and  211   b  may be used to apply an electric field to the image-forming layers  204  and  208  of an image member  200 , shown in  FIG.  2 A . Applying an electric field to the first and second image-forming layers  204  and  208  causes the particles to move within their respective capsules, adjusting the respective optical properties of the image-forming layers. The plurality of electrodes  211   a  and  211   b  can control the first image-forming layer  204  and the second image-forming layer  208  from one side of the imaging member  200 , thereby eliminating the need for any intervening electrode or conductive layers that may adversely affect the light transmissivity of the device. Depending on the applied voltage waveform, the electrophoretic particles may be driven towards various locations within their respective capsules, adjusting the respective optical properties of the image-forming layers. For example, referring to  FIG.  2 A , the electrophoretic particles  209  in the first image-forming layer  204  and the electrophoretic particles  207  in the second image-forming layer  208  may have a similar charge polarity and may be driven towards a transparent “open” state, wherein the particles aggregate towards the lateral walls of the capsules. 
     In another example depicted in  FIG.  2 B , an image member  250  comprises electrodes  251   a  to  251   d  that are in the form of concentrator electrodes. The electrophoretic particles  209  in the first image-forming layer  204  and the electrophoretic particles  207  in the second image-forming layer may have a similar charge polarity, such that the particles in both image-forming layers may be driven towards the plurality of electrodes. In this example, the particles  209  in the first image-forming layer  204  are shuttered by being concentrated into a small area in proximity to the electrode. Similarly, because the microcapsules  205  in the second image-forming layer  208  may include a conical or pyramidal-shaped well  203 , the particles  207  in the second image-forming layer  208  may also be shuttered by concentrating the particles  207  into a small area, thereby providing an imaging member with a transparent optical state. 
     In  FIG.  2 C , addressing the microcapsules at a different frequency or voltage may cause the particles  209  to spread out, such that an observer will observe the optical property of the particles  209 . In  FIG.  2 D , the polarity of the electric field is reversed, in relation to the electric field of  FIG.  2 C . As a result, the particles  209  in the first image-forming layer  204  are shuttered by concentrating the particles  209  into the conical or pyramidal-shaped wells  201  of the microcapsules  215  in the first image-forming layer  204 , and the particles  207  are spread out on one side of the microcapsules  208 , so that the optical property of the particles  207  may be observed. As illustrated in  FIG.  2 E , because the electrodes  211   a  and  211   b  are independently addressable, the image-forming layers  204  and  206  may be adjusted differently in different pixel locations. 
     The imaging member  200  (illustrated in  FIGS.  2 A to  2 E ) may further include a protective layer  214  that may be adhered to the second image-forming layer  208  with an adhesive, preferably an optically clear adhesive. If the device is viewed from the side of the protective layer  214 , the protective layer  214  is preferably light-transmissive. In addition, if the device is a reflective display, an optional reflective layer  212  may be incorporated below the first image-forming layer  212 . In another embodiment, the substrate  210  may include a reflective material. Alternatively, if the reflective display is viewed from the opposing side (not from the side of the protective layer), the substrate  210  is preferably light-transmissive, and the protective layer  214  may be reflective. In yet another embodiment, the imaging member  200  may be used to form an emissive display, wherein it is preferred that both the protective layer  214  and substrate  210  are light-transmissive, so that a backlight may be applied to either side of the imaging member  20 . 
     The imaging member may be further combined with a controller (not shown in  FIGS.  2 A to  2 E ) that, upon receiving a desired three-dimensional image, can compute an image to be produced on the first image-forming layer  204  and second image-forming layer  208 . The controller may then control the plurality of electrodes to apply the electric field to microcapsules  205 ,  215  that will form the two images and generate an autostereoscopic image. The computation may be performed locally or remotely. 
     The foregoing has been a detailed description of illustrative aspects of the invention. Various modifications and additions can be made without departing from the scope thereof. Furthermore, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described. For example, any of the various features described herein can be combined with some or all of the other features described herein according to alternate aspects. While the preferred aspect has been described, the details may be changed without departing from the invention, which is defined by the claims. 
     Finally, it is expressly contemplated that any of the processes or steps described herein may be combined, eliminated, or reordered. In other aspects, instructions may reside in computer readable medium wherein those instructions are executed by a processor to perform one or more of processes or steps described herein. As such, it is expressly contemplated that any of the processes or steps described herein can be implemented as hardware, software, including program instructions executing on a computer, or a combination of hardware and software. Accordingly, this description is meant to be taken only by way of example, and not to otherwise limit the scope of this invention.