Transparent-scattering type optical device including a prism with a triangular longitudinal cross section

A transparent-scattering type optical device comprising:

• a transparent-scattering type optical element, said element comprising a transparent-scattering mode optical material layer whose light scattering characteristics are changed in response to an external input;
• and
• two or more prisms having a same bottom surface attached to the back surface of said transparent-scattering type optical element, wherein said prisms each have a longitudinal cross section of a shape which is either triangular or triangular with a top portion cut away, and
• wherein said prisms are provided in a side-by-side relation and the recessed valley portion formed between a pair of adjacent prisms functions as an absorbing face.

A transparent-scattering type display apparatus comprising:

• a transparent-scattering type optical element, said element comprising a transparent-scattering mode optical material and having patterned electrodes,
• wherein light scattering characteristics of said element are changed at each of the electrodes in response to an external input, and a display image of said element is formed according to the operation of said patterned electrodes;
• and
• at least one prism having a bottom surface attached to the back surface of said transparent-scattering type optical element,
• wherein said prism has a longitudinal cross section of a shape which is either triangular or triangular with a top portion cut away, and
• wherein first and second angles formed by two sides of the triangular longitudinal cross section of the prism and said bottom surface are each between 65.degree. and 90.degree., inclusive, such that one of said angles does not equal 90.degree., and wherein an area defined by portions of the side surfaces of the prism nearest to the top of the prism or, when the top portion is cut away, a portion of the top face of the prism, functions as absorbing faces or an absorbing face, respectively.