Reflective image-providing display viewed with holographically diffused ambient light

DETAILED DESCRIPTION OF THE INVENTIVE SUBJECT MATTER The present invention encompasses a display viewable by reflection, the display comprising an image-providing display element and a reflective holographic diffuser.
The image-providing display element is one that is capable of providing an image viewable by the transmission of light therethrough.
Examples of such images include, but are not limited to, images produced by addressable electrooptical devices, such as liquid crystal display elements and electrophoretic display elements; and static light-transmissive images, such as binary images provided on a light-transmissive substrate and photographic slides.
In accordance with the present invention, the reflective holographic diffuser is positioned proximate to (e.
g.
, spaced apart proximately or contiguous with) the image-providing display element, whereby the image-providing display element is made reflectively viewable.
The reflective holographic diffuser comprises a light-reflective layer and a holographic transmission diffuser.
With regard to embodiments involving static fight-transmissive images, by way of illustration, a reflective holographic transmission diffuser can be applied onto, for example, an initially light-transmissive display in the nature of a "sign", thus converting said sign to a reflectively-viewable sign.
A resultant sign can be made to utilize ambient light to give the effect of an electrically illuminated backlit sign.
In such embodiment, the sign may utilize an "off-axis" diffuser which would take incident overhead light and reflect it horizontally toward a predetermined viewing location.
Similar use of the reflective holographic diffuser as a light-manipulating backing can be accomplished with photographic slides or other like imaged transparencies.
In such embodiments, due to relatively more relaxed optical requirements, the reflected holographic diffuser need not be based on the combination of a holographic transmission diffuser and reflection layer.
Although still confined by the aforediscussed inherent limitations, a reflective holographic diffuser based on a volume phase reflection hologram can be employed