Abstract:
Optical wave guide panel for visualization of an image, wherein the panel has an image interface surface for interfacing with an image to be visually presented and a viewing interface surface opposite the image interface surface for reviewing the image located at the image interface surface. The panel has at least one boundary, and is fabricated from a transparent solid material. The panel is provided with a pattern of grooves and to the image interface surface, extending at lease partially into the panel between image interface surface and the viewing interface surface of the panel. The pattern of grooves comprises at least one groove following a contour of the at least one boundary of the panel. The boundary of the panel exhibits an angle with respect to the at least one groove, such that a length of a panel segment, defined by the groove following the contour of the at least one boundary and the boundary at the viewing interface surface, along a cross section of the panel transverse to a direction of said at least one groove is greater than a length of the segment at the image interface surface along the cross section.

Description:
FIELD OF THE INVENTION 
       [0001]    The invention relates to an optical wave guide panel for visualization of an image visual presentation an assembly comprising at least one visual presentation and a corresponding optical wave guide panel, a visual presentation and a method of manufacturing a visual presentation assembly. 
       BACKGROUND 
       [0002]    Certain visual presentations may comprise an image portion and be surrounded by a frame portion, which frame portion does not contain image information. When such an image is to be visually presented, such that the frame portion is not visible, but within the limits defined by the outer circumference of the frame portion, optical means can be used to enlarge the image such that it can be viewed within the outer circumference of the frame portion, by guiding light irradiated from or reflected from the image surface. 
         [0003]    Such optical guidance means are known for example from U.S. Pat. No. 4,139,261 where by means of optical fibers a composite visual presentation of increased area is constructed. The fiber optic image transform construction of this guidance means is arranged in front of a plurality of visual presentation panels for transforming an image collectively provided by panels into a corresponding continuous image in which discontinuities between adjacent panels visual presentation zones are eliminated. 
         [0004]    In published US patent application 2011/0102302 A1 a direct viewing type visual presentation device is disclosed having at least one visual presentation panel having visual presentation region and a frame region provided outside a visual presentation region with a boundary extending along the first direction between a visual presentation region and a frame region and at least light transmitting cover disposed on a viewer side of the at least one visual presentation panel. The panel cover includes a lens portion disposed a astride the boundary for refraction a portion of light emitted from a visual presentation region towards the frame region and a viewer side surface of the lens portions is a curved surface and a rear side surface of the land portion is also a curved surface. This structure allows seamless visual presentation of an image in a case of tiled images. 
         [0005]    Furthermore from published US patent application no. 2005/0140613 A1 an image visual presentation is disclosed comprising an image visual presentation device having a ray of electrically driven picture elements which are viewable at a viewing interface surface. An optical device comprising a plurality of mechanically bonded waveguides having a surface adapted to a surface of an image or visual presentation to be visually presented and a viewing interface surface, wherein optical wave guide fibers guide the light from the image side to the viewing side of the panel such that the image can be viewed at the viewing interface surface side having an apparent form and size corresponding to the outer circumference of the image edge. 
         [0006]    Solutions having optical fibers, such as U.S. Pat. No. 4,139,261 and US 2005/0140613 A1 are disadvantageous as the fibers comprised in such solutions are to be mechanically bonded and supported. Other solutions such as described in US2011/0102302 comprising a lens like optical guidance are disadvantageous since their viewing angle may be limited. 
       SUMMARY 
       [0007]    It is therefore an object of the invention to provide optical guidance means that overcomes the disadvantages known in the art. The object is achieved in an optical wave guide panel for visualization of an image, wherein the panel is fabricated from a transparent solid material. The panel comprises an image interface surface and a viewing interface surface opposite the image interface surface, at least one boundary, a pattern of grooves, the grooves extending at least partially into the panel between the image interface surface and the viewing interface surface of the panel. The pattern of grooves comprises at least one groove following a contour of the at least one boundary of the panel. The boundary of the panel exhibits an angle with respect to the at least one groove, such that a length of a panel segment, defined by the groove following the contour of the at least one boundary and the boundary at the viewing interface surface, along a cross section of the panel transverse to a direction of said at least one groove is greater than a length of the segment at the image interface surface along the cross section. 
         [0008]    This causes light irradiating from or reflected on the image interface surface to spread over the viewing interface surface. The image part covered by the image interface surface delimited by at least one groove and the boundary appears enlarged at the viewing interface surface, and may be viewed from a larger range of a viewing angles. Due to the grooves which extend at least partially into the panel towards a viewing interface surface, the panel is formed continuously. Thus it is no longer necessary to position and fixate optical wave guide fibers in order to obtain the desired effects. 
         [0009]    In an embodiment, the grooves extend at least partially into the panel from the image interface surface towards the viewing interface surface of the panel. 
         [0010]    In an embodiment the optical wave guide panel comprises an inclined side of the panel. The inclined side allows reflection of incident light at the viewing interface surface towards the image interface surface and vice versa. 
         [0011]    In an embodiment the boundary comprises the curved side of the panel. This allows more freedom in the design and manufacturing of the wave guide panel with respect to optimization of visibility of the seams as a function of the viewing angle. 
         [0012]    In a further embodiment the optical wave guide panel comprises a truncated edge, such as a facet or a curved surface extending from the viewing interface surface to substantially the boundary up to the upper level of the at least one groove. This allows a larger viewing angle at the viewing interface surface side of the panel and less distortion of a perceived picture element size at the truncated edge of the panel. 
         [0013]    In an embodiment the boundary comprises a side of a wedge shaped groove, partially extending perpendicularly from the image interface surface into the panel. This allows a plurality of optical wave guide panel segments to be formed from a single panel, such that a plurality of images of the image interface surface can be accommodated. 
         [0014]    In an embodiment the panel material has a first optical refractive index and each groove is filled with a medium having a second optical refractive index, lower than the first optical refractive index. This allows incident light in and light irradiated from the visual presentation to be reflected along the grooves. 
         [0015]    In an embodiment, the grooves are formed in a first surface in a regular pattern. This allows application of the panel in combination with for example pixel oriented visual presentations as image forming device at the image interface surface side of the panel. Pixel oriented devices generally have the pixels arranged in a regular pattern. In a further embodiment the panel has a rectangular or a square shape. This also allows application of the panel with image forming devices or images which have such rectangular or square shape. 
         [0016]    In a further embodiment the at least one groove following the boundary is positioned parallel to the boundary. 
         [0017]    In an embodiment of the optical waveguide panel, the grooves are found perpendicular relative to the image interface surface. The allows for easy manufacturing of the grooves, since all grooves have the same perpendicular angle with respect to the image interface surface. As the area of the image interface surface between the groove and boundary of the panel is smaller than the predicted area of the viewing interface surface opposite of the panel, the effect of masking the frame portion of the image or visual presentation placed at the image interface surface side of the panel is preserved. 
         [0018]    In an embodiment the grooves of the optical wave guide panel are found in a fan-shaped fashion in a cross section of the panel perpendicular to the grooves. The allows an even distribution of the grooves as viewed from the image interface surface side and the viewing interface surface side of the panel respectively. This is especially advantageous for interfacing with visual presentations having picture elements or pixels of equal size arranged in a regular pattern. 
         [0019]    The object is also achieved in a visual presentation assembly comprising at least one visual presentation and a corresponding optical wave guide panel as described above. The wave guide panel is mounted on a visual presentation, the visual presentation comprises an image portion having image elements and a frame portion, wherein the dimensions of the optical wave guide panel image interface surface matches with the dimensions of the image portion of the visual presentation, such that the boundary of the optical wave guide panel overlaps with the frame portion of the visual presentation. 
         [0020]    The assembly allows multiple visual presentations to be presented by means of the corresponding wave guide panels whereby the seams formed by the frame portions of the visual presentations are made invisible. Thus an integrated visual presentation assembly having multiple visual presentations appears to a viewer as a single visual presentation, not showing seams or frame portions. 
         [0021]    In an embodiment the optical wave guide panel corresponds to a plurality of visual presentations arranged in tiles positioned adjacent to each other. 
         [0022]    In an embodiment the boundary of the optical wave guide panel is positioned such that it is aligned with a transition between two visual presentations. 
         [0023]    In an embodiment a medium is applied between said optical wave guide panel and said visual presentation, wherein the medium has a refractive index which approximate refractive index of the material of the optical wave guide panel. 
         [0024]    This allows light emitted from the visual presentation, or reflected therefrom without reflection of said reflected or emitted light by the image interface surface. 
         [0025]    In another embodiment, the panel comprises a diffusion layer applied to said viewing interface surface. This causes light emitted from picture elements from a light emitting visual presentation at the image interface surface, such as a display or incident light to be diffused such that the picture elements appear evenly across its surfaces, reducing any reflected light by the grooves or boundary and masking any obstructive visible feature at the viewing interface surface of the panel, such as undesired reflections from the grooves. 
         [0026]    The object is also achieved in a visual presentation comprising an image portion having image elements and a frame portion, wherein the image elements adjacent to said frame portion have a width such that the width of said image elements added to a width of said frame portion equals a width of image elements non-adjacent to said frame portion. Such a visual presentation having pixels with unequal size at the frame portion of the visual presentation, where the size is compensated for the width of the frame portion of the visual presentation, can be used in combination with an optical wave guide panel having grooves formed perpendicularly to the image interface surface of the panel, provided that the grooves are aligned with the pixel boundaries of the visual presentation. 
         [0027]    In a preferred embodiment the visual presentation has a rectangular or square shape. 
         [0028]    The object is also achieved in a method for manufacturing a visual presentation assembly as described above. The method comprises the steps of providing a visual presentation comprising an image portion having image elements and a frame portion, providing an optical wave guide panel, joining the visual presentation and the optical wave guide panel, aligning a frame portion of the visual presentation with the boundary of the optical wave guide panel and aligning the grooves in the panel with corresponding image element boundaries. 
         [0029]    In an embodiment the step of joining further comprises applying a medium between said optical wave guide panel and the visual presentation, wherein the medium as a refractive index approximates the refractive index of the material of the optical wave guide panel. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0030]      FIG. 1 a    shows a top view of visual presentation. 
           [0031]      FIG. 1 b    shows a combination of visual presentations arranged adjacent to each other. 
           [0032]      FIG. 1 c    shows an alternative top view of a visual presentation. 
           [0033]      FIG. 1 d    shows an alternative top view of a visual presentation. 
           [0034]      FIG. 2 a    shows a cross section of an optical waveguide panel according to an embodiment of the invention. 
           [0035]      FIG. 2 b    shows a cross section of the optical waveguide panel of  FIG. 2 a    in combination with a cross section of an visual presentation. 
           [0036]      FIG. 2 c    shows a cross section of the optical waveguide panel, according to an embodiment of the invention. 
           [0037]      FIG. 2 d    shows an end section of an optical waveguide panel according to an embodiment of the invention. 
           [0038]      FIG. 3 a    shows a cross section of an optical waveguide panel according to an embodiment of the invention. 
           [0039]      FIG. 3 b    shows the cross section of the waveguide panel according to  FIG. 3 a    in combination with a visual presentation. 
           [0040]      FIG. 4  shows a visual presentation adapted according to an embodiment of the invention. 
           [0041]      FIG. 5 a    shows a cross section of a combination of two optical waveguide panels according to an embodiment of the invention. 
           [0042]      FIG. 5 b    shows a cross section of a combination of two optical waveguide panels according to an embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0043]      FIG. 1 a    shows a visual presentation  11  having an image portion  12  and a frame portion  13 . The image portion  12  is subdivided into picture elements  14 , however a plain image portion is also possible. The visual presentation  11  in the example of  FIG. 1 a    is shown having a rectangular shape, but also other regular shapes, but not necessarily rectangular may apply. Image portions  12  having picture elements  14 , such picture elements can have dimensions L 1 , L 1 ′. The frame portion may have dimensions d or d′ for horizontal and/or vertical portions respectively.  FIG. 1 b    shows four visual representations according to  FIG. 1 a   , connected together at the frame portions  13  were appropriate. A connection of two respective frame portions  13  causes a seam to be visible which causes a disturbance for a viewer in the overall view of the visual presentation combination. 
         [0044]      FIG. 1 c    shows a viewing interface surface, i.e. top view, of an visual presentation  11  with picture elements  14  in a diamond shaped pattern. The picture elements  14  and boundaries  15  between the picture elements  14  may be curved, as is shown in  FIG. 1   d.  The shape of the visual presentation may be designed such that a plurality of presentations can be concatenated, i.e. tiled with an together with subsequent optical waveguide panels  21  according to the invention. 
         [0045]      FIG. 2 a    shows a partial cross section of an optical waveguide panel  21  to be aligned with a visual presentation according to  FIG. 1 a    along the line A-A′. The optical wave guide panel  21  extends in the two dimensions corresponding to a visual presentation  11  according to any of the  FIGS. 1 a   - 1   d.  The optical wave guide panel  21  has a viewing interface surface  25  and an image interface surface  24  for interfacing with the image portion  12  of a visual presentation  11 . The optical waveguide panel  21  has grooves  23  extending into the waveguide panel  21  body, thereby forming segments  22   n - 3 ,  n - 2 ,  n - 1 ,  n . Each groove  23  has its own angle with respect to its predecessor and successor as shown for example between segments  22   n - 2 ,  n - 1  having a respective angle α n-1  and segment n- 1  and n having a respective angle α n  with respect to the boundary  26  of the waveguide panel  21 . In this fashion, the grooves as viewed along the cross section are structured in a fan-shaped manner. The optical waveguide panel  21  has grooves  23  structured likewise in the transverse direction of the line A-A′ corresponding to any one of the examples of the visual presentation of  FIGS. 1 a   - 1   d.    
         [0046]    The grooves  23  in  FIGS. 2 a -2 b    are shown extending into the panel  21  between the image interface surface  24  to the viewing interface surface  25 . The grooves  23  can be formed from the image interface surface  24  into the panel  21  by for example laser cutting. The grooves  23  may be closed at the image interface surface  24  after cutting by partially filling with for example a resin which is cured afterwards, as shown in  FIGS. 2 a  and 2 b   . In that case also another medium is possible. Likewise the grooves  23  can be formed starting from the viewing interface surface  25  side. 
         [0047]    As is shown in  FIG. 2 a   , the segments  22  have a length L 1  when viewed from the image interface surface  24  side, whereas at the viewing interface surface side  25  of the panel  21  the segments have a length L 2  in the direction A-A′ at the image interface surface side  24 , which is larger than L 1 , caused by the successive angles between the grooves  23  separating each segment  22   n - 3 , . . . ,  n.    
         [0048]    The thickness of the optical waveguide panel  21  is denoted by “h 1 ” and the depth of the grooves  23  extending into the panel is denoted by “h 2 ”. The length L 2  is defined by the intersections of the grooves  23  with the viewing interface surface  25  if the grooves  23  would be extended all the way through the optical waveguide panel  21 . 
         [0049]    The boundary  26  of the optical waveguide panel  21 , at the last segment  22  near the edge of the panel  21  substantially has an inclined surface, such that the viewing interface surface  25  has a length L 2  along the line A-A′ which is larger than the corresponding length L 1  along the image interface surface  24 , the difference at boundary  26  being denoted by d. 
         [0050]    The optical waveguide panel  21  is constructed from an optical transparent material, such as glass, Perspex, acryl, polycarbonate, etcetera. When left open the grooves  23  are preferably filled with air as medium, but other media may be used as long as the medium refractive index is lower than the refractive index of the panel  21  material. A medium other than air can be used especially when the grooves  23  are closed after cutting and filling with the medium. In such case the grooves  23  can alternatively be cleared of any medium and put into a vacuum state. 
         [0051]    The viewing interface surface  25  may be provided with a diffusion layer for example by applying a diffuser film to its surface. Otherwise, the viewing interface surface  25  may be etched or otherwise modified to this effect. 
         [0052]    In  FIG. 2 b    the cross section of the optical waveguide panel  21  is shown in combination with a cross section of a visual presentation  11  subdivided into picture elements  14 . The optical waveguide panel image interface surface  24  is aligned with the visual presentation  11  such that the image interface surface  24  contacts a top surface of the visual presentation  11  and the frame portion  13  of the visual presentation  11  is aligned with the edge  28  of the viewing interface surface  25  of the optical waveguide panel, see dotted line x. A viewer  29  at the viewing interface surface  25  side of the panel  21  viewing the visual presentation  11  at the image interface surface  24  side of the panel  21 , will perceive the visual presentation  11  subdivided in segments determined by the grooves  23  as determined at level h 2  at the surface of the image portion of the visual presentation  11 , slightly enlarged and such that the frame portion  13  of the visual presentation  11  is hidden underneath edge  28  of the panel viewing interface surface  25 . 
         [0053]    A viewer  29  viewing the viewing interface surface  25  of the panel  21  perceives light emitted from a light source  61  which is refracted by the image interface surface  25 , specularly or diffusely reflected by the picture element  14  of the visual presentation  11 , reflected by the groove  23  and refracted towards the viewer  29  by the viewing interface surface  25 . 
         [0054]    A transparent, light conducting second medium can be inserted between the top side of the image forming portion  12  of the visual presentation  11  and the image interface surface  24  of the optical wave guide panel  21 , not shown in  FIG. 2 b   . The optical refractive index of the second medium is preferably near the optical refractive index of the panel  21  material, such that light can be exchanged between the panel  21  and the visual presentation  11  such that reflection at the image interface surface  24  of the optical waveguide panel is minimal. For this purpose for example acrylic Tesa ACX plus  film can be used. 
         [0055]    The edge  28  in  FIG. 2 b    can be truncated as shown in  FIG. 2 c    for example by means of a facet  27 . Instead of a facet, the boundary may also be curved. The truncated edge  27  extends from the viewing interface surface  25  towards the boundary  26  of the panel  21  such that it intersects with the boundary  26  at a distance approximately h 2  from the image interface surface  24  of the panel  21 . This allows a larger viewing angle at the viewing interface surface side of the panel and less distortion of the perceived pixel size at the edge of the panel. 
         [0056]    The boundary  26  which is shown in  FIGS. 2 a -2 c    as an inclined side of the panel  21 , may also be curved as shown in  FIG. 2 d   . This allows more freedom in the design and manufacturing of the wave guide panel with respect to optimization of visibility of the seams as a function of the viewing angle. 
         [0057]      FIG. 3 a    shows a partial cross section of an optical waveguide panel  21  to be aligned with a visual presentation  32  along the line B-B′ of  FIG. 4 . In  FIG. 3 a    it is shown that the grooves  23  may also extend perpendicularly with respect to the image interface surface  24  into the panel  21 . Also in  FIGS. 3 a    (and  3   b ) it is shown that the grooves  23  can extend from the image interface surface  24  into the panel  21 . An outer most groove  23  has an angle β with boundary  26  of the panel  21 . The boundary  26  is shown as inclined side of the panel such that edge  28  projects from the panel over a distance d. 
         [0058]    As a consequence the segments  22   n - 3 ,  n - 2 ,  n - 1  do not have the same length L 1  along the line A-A′ in comparison with segment  22   n . Segment n is substantially shorter than for example segment n- 1 , such that L 1 =L 2 =L 3 +d. 
         [0059]    As a consequence, when the panel of  FIG. 3 a    is combined with the visual presentation  11  as is shown in  FIG. 3 b   , an edge picture element  31  of the image portion of the visual presentation  11  has to be aligned with the shorter base with length L 3  of the image interface surface  24  of the panel  21 . Edge  28  of the viewing interface surface  25  of the panel  21  is aligned with the outer edge of the frame portion  13  of the visual representation  32  of  FIG. 4 . Like in  FIG. 2 b   , a viewer  29  viewing the visual presentation  11  through the optical waveguide panel  21  will perceive the edge of the image portion of the visual presentation  32  having the same size L 2  as the other picture elements  14  of the image portion of the visual presentation  32 . 
         [0060]    Like in the example of  FIG. 2 b   , but not shown in  FIG. 3 b   , a second medium can be applied between the visual presentation  32  and the optical waveguide panel image interface surface  24 , to minimize reflection at this interface surface  24 . Illustrated in  FIG. 3 b    is also light from a light source  61  reflected at the boundary  26 , a top surface of a picture element  14  of visual presentation  11 , groove  23 , refracted at the viewing interface surface  25 , reaches a viewer  29  at the viewing interface surface side of the panel  21 . Edge  28  is aligned with the frame portion  13  of the visual presentation  11  along line y. Furthermore, like in  FIG. 2 c   , edge  28  can be a truncated edge  27 . 
         [0061]      FIG. 4  shows a visual presentation  32  for use with the optical waveguide panel  21  of  FIGS. 3 a  and 3 b   . Picture element  31  bordering the frame portion  13  of the visual presentation  32  has smaller dimensions L 3 , L 3 ′ than the picture elements  14  in the central part of the visual presentation portion  12  of the visual presentation  32  to compensate for the length d, d′ of the frame portion  13  of the visual presentation  32 .  FIGS. 5 a  and 5 b    show variations of the way more than one optical waveguide panels  21 ,  21 ′ can be combined. In  FIG. 5 a    the panels  21 ,  21 ′ are aligned such that the edges  28 ,  28 ′ of the viewing interface surfaces  25 ,  25 ′ of those panels  21 ,  21 ′ are aligned. As a consequence, it is clear that frame portions  13 ,  13 ′ of the visual presentation  11 ,  11 ′ are no longer visible for a viewer  29  viewing the combination of panels from the viewing surface  25  side. 
         [0062]    In  FIG. 5 b    it is shown that the edge portions  28 ,  28 ′ of the respective panels  21 ,  21 ′ can be merged, such that at the junction  51  the respective panels  21 ,  21 ′ appear as a single panel. In both  FIGS. 5 a , and 5 b   , the boundary  26 ,  26 ′ in cooperation with the grooves  23 ,  23 ′ cause visual presentations  11 ,  11 ′ to appear as one, such that frame portions  13 ,  13 ′ are no longer visible.
   For all examples, a visual presentation  11 ,  32  may be formed by a picture, photo, drawing, poster and even a decoration tile and the like. Preferably a visual presentation is formed by a display, such as an Liquid Crystal Display, LED display, electrowetting display and the like, which have an image portion having picture elements or pixels in a regular pattern. The optical wave guide panels  21  described above have grooves  23  and segments  22  that correspond to the pixel pattern of the display, such that the pattern of grooves  23  in the image interface surface  24  of the panel  11 ,  32  align with the picture element boundaries  41  of the display or visual presentation  11 ,  32 . Vice versa, picture elements  14 ,  31  of visual presentations  11 ,  32  may be designed to correspond to the grooves  23  pattern at the image interface surface  24  of an optical waveguide panel  21 .   
 
         [0064]    All embodiments described above are presented by way of example only, not limiting the scope of protection conferred by the claims presented below.