BACKLIGHTING APPARATUS EMPLOYING AN ARRAY OF MICROPRISMS

摘要

An improved backlighting apparatus comprising a slab waveguide (6) that acce pts light rays generated by a light source (4) and transmits the light rays via total internal reflection. Attached on one face of the slab waveguide is an array of microprisms (28), with each microprism (28) having a light input surface (30) parallel to a light output surface (32) and at least one sidewall (33) tilted at a n angle from the direction normal to the surface of the waveguide (6) such that ligh t rays escape from the slab waveguide (6), reflect off t he tilted sidewall (33) and emerge from the microprism (28) as a light source substant ially perpendicular to the light output surface (32). An array of microlenses may be positioned to accept the output of the microprisms so that the light exiting from the microlenses is substanti ally more perpendicular. The backlight apparatus is advantageously used as a back lighting means for flat panel electronic displays.