Abstract:
An image display device, including: a luminous display having a light emitting face for providing a luminous image; and a reflective image in a screen pattern located on the light emitting face, whereby when the luminous display is emitting light, the luminous image dominates, and when the luminous display is not emitting light the reflective image dominates.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates to image display devices, and more particularly to an image display device that displays a reflection image and a luminous image.  
         BACKGROUND OF THE INVENTION  
         [0002]    It is known to provide luminous image displays that emit light in an imagewise pattern from an array of light emitting elements. Examples of imagewise addressable luminous displays are CRT&#39;s, organic light emitting diode (OLED) displays and plasma displays. It is also known to provide luminous image displays that employ a non imagewise light source, located behind an imagewise light modulator. Examples of such none imagewise light source luminous displays include fixed displays such as back lit photographic transparencies, and addressable displays such as back lit liquid crystal displays.  
           [0003]    It is also known to provide an electronic image display device tailored specifically for displaying digital still images. An example is the Kodak Smart Picture Frame that includes a digital camera card reader, full-color display and modem. The Kodak Smart Picture Frame can display a single image or sequentially cycle through up to 36 separate fall-color digital pictures. The user inserts a COMPACTFLASH memory card from a digital camera to display and view images on the frame. Using a built-in slide show function, pictures can be sequentially displayed for an ever-changing display. The frame owner can select how long a given image is displayed—from 5 seconds to a full day. The frame can double as an information appliance, delivering news, weather, traffic, fine art and other information.  
           [0004]    One drawback of such luminous displays is that they need to be continuously powered to display the images. If powered by line current, they are not completely portable. If powered by batteries, they rather quickly deplete the batteries, requiring inconvenient recharging or expensive battery replacement.  
           [0005]    When the power to an addressable image wise luminous display is turned off to save energy and or save the lifetime of the battery or the device itself, a flat uniform appearance is generally presented. When the power to a non image wise light source luminous display (e.g. a backlit transparency) is turned off, such as during the day, an image of poor quality can result.  
           [0006]    There is a need therefore for a luminous display device that does not require continuous power, but which can display a good quality image when the power is turned off.  
         SUMMARY OF THE INVENTION  
         [0007]    The need is met according to the present invention by providing an image display device that includes: a luminous display having a light emitting face for providing a luminous image; and a reflective image in a screen pattern located on the light emitting face, whereby when the luminous display is emitting light, the luminous image dominates, and when the luminous display is not emitting light the reflective image dominates. In one embodiment of the invention, the luminous image is a motion image sequence and the content of the reflection image is related to the content of the luminous image.  
         ADVANTAGEOUS EFFECT OF THE INVENTION  
         [0008]    The advantage of this invention is that the when an emitting device is not powered, a static image can be seen in reflection in contrast to the uniform blank images provided with standard display devices. The content of the reflection image can be related to the content of the luminous image. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]    [0009]FIG. 1 is a schematic diagram showing a display device according to the present invention;  
         [0010]    [0010]FIG. 2 is a cross sectional view of a portion of the display screen having a shadow mask image according to the present invention;  
         [0011]    [0011]FIG. 3 is a plan view of a shadow mask having a permanent image formed thereon according to the present invention;  
         [0012]    [0012]FIG. 4 is a schematic diagram representing an image motion sequence displayed on the display device of the present invention;  
         [0013]    [0013]FIG. 5 is a schematic diagram showing a laser writer for making one embodiment of a reflective screen used with the present invention;  
         [0014]    [0014]FIG. 6. is a schematic diagram showing a lamination step used in the manufacture of a reflective screen used with one embodiment of the present invention; and  
         [0015]    [0015]FIG. 7 is a schematic side view of a display device according to one embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0016]    In luminous display devices, often only a portion of the image area emits light. In some devices, light emitting pixel elements are separated from adjacent pixels by region which include electrical lines and transistors necessary for operation of the pixels in the device. This region can be a significant fraction of the total area (e.g.&gt;50%) of the luminous display. These non light emitting regions are not visible when the device is in operation because when the luminous display is emitting light, the luminous image dominates. When the luminous display is turned off, these non light emitting regions are featureless and not visually appealing.  
         [0017]    According to the present inventio, a reflective image is placed over these non light emitting regions. In this manner when the luminous display is turned on, the emitted light is much greater than the ambient light reflected from the reflective image and the luminance image dominates. When the luminous display is turned off, the reflected light from the reflective image dominates.  
         [0018]    In a similar manner, a continuous luminous image such as a backlit transparency image can be provided with a reflective image that covers only a portion of the transparency in a screen pattern, such that when a the backlight is on the transparency image predominates, but when the backlight is turned off the reflective image predominates.  
         [0019]    To produce a luminous display device according to the present invention, a conventional luminous display, such as an OLED display, backlit liquid crystal display (LCD), cathode ray tube (CRT), or backlit transparency is manufactured and then a static reflective image is applied in a screen pattern to the light emitting surface of the display, for example by laser dye transfer, thermal transfer, electrophotography, inkjet, or other high resolution printing technique well known in the art. The reflective image is applied in a regular pattern such that the printed region covers more than 10% of the available image area. Preferably, the reflective image is located over non light emitting portions such as circuitry of the luminous display.  
         [0020]    Referring to FIG. 1, an image display device  10  according to one embodiment of the present invention, includes a luminous display such as an organic light emitting diode (OLED) display  12 . Drive electronics  14  are connected to the luminous display  12  to drive the display to cause it to display a still image or a motion image segment. A memory  16  for holding digital image data representing the still or motion image segment is connected to the drive electronics  14 . A power supply  18 , preferably a battery, is connected to power the components of the display device  10  through a switch  20  that can be activated to temporarily apply power to the drive electronics to cause the luminous display to display the still or motion image sequence. An input/output port  22 , such as USB port is provided for supplying the digital image data to the memory  16 . Optionally, a speaker  24  can be connected to the drive electronics to produce an audio clip to accompany the displayed image.  
         [0021]    Referring to FIG. 2, in one embodiment, the luminous display  12  is and organic light emitting diode (OLED) display that includes a transparent substrate  26 . An array of organic light emitting elements  28  and conductors  30  for powering the organic light emitting elements  28  are arranged on one side of the substrate  26 . The other side of the substrate is provided with a light reflective screen  32  that covers the regions between the light emitting elements  28 . The light reflective screen includes a reflective base layer  33 , such as a white pigment, covered by a color layer  35 . Referring to FIG. 3, an image  34  is formed by the color layer  35  on the light reflective screen  32 . The image  34  is clearly visible when the display device  10  is not powered. A detail of a portion of the image is shown in the inset  3   a  of FIG. 3.  
         [0022]    Referring to FIG. 4, when the display device  10  is powered by depressing switch  20 , a still or motion image sequence  36  is presented on the display device corresponding to the still or motion image sequence that is stored in memory  16 . The light from the display device swamps the image  34 , and the still or motion image sequence  36  is predominate.  
         [0023]    According to an alternative embodiment of the present invention, the memory  16  may contain an audio clip related to the motion image sequence, and the audio clip is played on speaker  24  when the video clip is displayed.  
         [0024]    The luminous display can also be an OLED device of the type that emits light from the same side of the display on which the light emitting elements are located. In this case, the reflective screen  32  with image  34  is formed on top of the light emitting surface of the display. This same arrangement can be used with a back lit liquid crystal display, or a back lit transparency. In the case of the transparency, the screen does not obscure any electronics, and may therefore be any perforated pattern that covers at least 10% of the display area.  
         [0025]    The two following examples were prepared to demonstrate the concept of a regular reflection image over a luminance image.  
       EXAMPLE 1  
       [0026]    Referring to FIG. 5, the reflective screen pattern  32  was formed on a substrate  40  using a laser writer  42  having a single laser  44 , which was focussed and scanned across a donor/receiver composite. Specifically, an SDL, Inc 1-watt diode laser (model 5400 C-mount laser) was used as the laser source  44 . This diode laser has a nominal operating wavelength of 830 NM. The output beam was shaped and oriented by beam shaping optics  46 , reflected off a scanning galvanometer  48 , and imaged on the substrate  40  through an F-theta lens  50 . All optics were antireflective coated for 830 NM to reduce power loss. The output beam  52  of the laser  44  was imaged onto the substrate  40  to yield a spot that was approximately 17 micron by 80 microns full width half minimum (FWHM). The scanning galvanometer  48  scans the beam  52  such that the long axis of the spot is always parallel to the scan. The galvanometer  48  and F-theta lens  50  combination was constructed to give 3.5 inches of scan.  
         [0027]    A substrate comprising a  104  micron film of polyethylene terephthalate was coated with nickel to an optical transmission density of 1.3. The laser writer  42  was used to ablate the nickel leaving clear spaces  54 , which were 70 microns wide separated by untouched metal stripes 90 microns wide.  
         [0028]    A white donor sheet  56  was prepared as taught in U.S. Pat. No. 6,190,827 issued Feb. 20, 2001 to Weidner, by coating a transparent support with a hydrophilic layer, a propellant layer comprising a gas producing polymer, and a colorant layer having a white pigment and an optical brightener. The white donor sheet was placed in contact with the metal lined side of the substrate  40  . The laser writer  42  was then used to transfer a white coating in registration with the metal lines on the substrate  40 . The resulting substrate with screen had a whitish-gray appearance when illuminated from the side having the screen and transparent when illuminated from the opposite side.  
         [0029]    A color image was then transferred to the screen using colored dye donor elements having a support with an image dye in an infra-red absorbing binder of the type described in U.S. Pat. No. 6,208,364 issued Mar. 27, 2001 to Tutt et al. The dye donor elements were placed in registration with the support  50  and a color image was transferred using the laser writer  42  onto the reflective screen  32  centered on the white lines and about  45  microns in width.  
         [0030]    Referring to FIG. 6, a transparent transfer laminate  58  coated on a carrier  60  was then applied to the support  40  over reflective image screen  32  by thermal transfer as detailed in U.S. Pat. No. 6,239,068 issued May 29, 2001 to Tutt et al. The transfer laminate carrier  60  was a 36 micron thick sheet of poly (ethylene terephthalate). Onto this carrier  60  was coated a layer containing 0.82 g/m2 polyvinybutyral (Butvar® 76, Monsanto Co.) and 0.02 g/m2 Fluorad FC 431® surfactant (3M Co). An adhesive layer was then coated over this layer consisting of 3.3 g/m2 of a sodium polyacrylate polymer (AQ55D, Eastman Chemical Co., Tennessee), 0.02 g/m2 of Olin 10 G (Olin Corp., Norwalk, Conn.) surfactant, 0.02 g/m2 of FT248 (Bayer Co., Germany) surfactant, and 0.02 g/m2 of Triton X 200E (Union Carbide Corp., Charleston, W. Va.) surfactant.  
         [0031]    Lamination of the protective material was effected by passing the substrate  40  with the reflective screen image  32  and carrier  60  with transfer laminate  58  through a laminator. The laminator  62  was a modified GMP Co. LTD (Kyoungki-Do, Korea) laminator model Passport 175LSI. The modification was to adjust the gap thickness to about a 1270 micron gap and disabling heating in the lower roller  64 . Lamination was conducted at 133 C. and a feed rate of 0.36 cm/sec. The transfer laminate was placed adhesive side to image side and the reverse side in contact with the heated roller  66 . Upon exiting the laminator  62  the 36 micron polyethylene terephthalate carrier  60  was peeled off and discarded. The lamination operation fused the dyes into the transfer laminate  58  and served to protect the image.  
         [0032]    Referring to FIG. 7, the resulting reflective image on substrate  40  was placed in front an image transparency  68  to form a display device according to one embodiment of the present invention. Under front lighting conditions from lamp  70 , with no back lighting, the reflective image predominated and was the only one visible. When transparency was illuminated from the rear by lamp  72 , the transparency image predominated and only the image in the transparency  68  was visible.  
       EXAMPLE 2  
       [0033]    According to this example, a support with a reflective screen image was generated as in Example 1. Next, a second unpatterned transparency color image was produced on the reverse side of the substrate  40  using the laser writer  42  and three subtractive color cyan, magenta and yellow (CMY) dye donors to sequentially write the unpatterned color image onto the reverse side of the substrate  40 . A clear laminate was then applied, as described above to this unpatterned color image on the back side of the support.  
         [0034]    When the support with the unpatterned transparency image on the back, and the reflective image on the front was illuminated from the front, the reflective image predominated and only the reflective image was visible. When support was illuminated from the backside, the transparency image predominated and only the transparency image was visible.  
         [0035]    The invention has been described in detail with particular reference to certain preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention.  
       Parts List  
       [0036]    display device  
         [0037]    luminous display  
         [0038]    drive electronics  
         [0039]    memory  
         [0040]    power supply  
         [0041]    switch  
         [0042]    I/O port  
         [0043]    speaker  
         [0044]    transparent substrate  
         [0045]    OLED element  
         [0046]    conductor  
         [0047]    reflective screen  
         [0048]    reflective base layer  
         [0049]    image on screen  
         [0050]    color layer  
         [0051]    motion image sequence  
         [0052]    substrate  
         [0053]    laser writer  
         [0054]    laser  
         [0055]    beam shaping optics  
         [0056]    scanning galvanometer  
         [0057]    F-theta lens  
         [0058]    output beam  
         [0059]    clear spaces  
         [0060]    white donor sheet  
         [0061]    transparent laminate  
         [0062]    aminate carrier  
         [0063]    laminator  
         [0064]    lower laminator roller  
         [0065]    heated roller  
         [0066]    transparency  
         [0067]    front lamp  
         [0068]    rear lamp