US Patent No. 9,110,361

ILLUMINATION OPTICAL SYSTEM AND PROJECTION DISPLAY APPARATUS


Patent No. 9,110,361
Issue Date August 18, 2015
Title Illumination Optical System And Projection Display Apparatus
Inventorship Atsushi Katou, Tokyo (JP)
Assignee NEC DISPLAY SOLUTIONS, LTD., Tokyo (JP)

Claim of US Patent No. 9,110,361

1. An illumination optical system, comprising:
two solid-state light sources;
a first light guide configured to guide light emitted from one of the two solid-state light sources in a first direction;
a second light guide configured to guide light emitted from another one of the two solid-state light sources in a second direction
different from the first direction; an optical path conversion unit including a total reflection surface for totally reflecting
the lights guided by the first light guide and the second light guide to enter the lights into a third light guide; wherein

an incident light that enters the total reflection surface at an angle equal to or larger than a critical angle is totally
reflected on the total reflection surface and incident light that enters the total reflection surface at an angle less than
the critical angle is transmitted through the total reflection surface; and

a reflection unit disposed oppositely to the total reflection surface via an air layer andconfigured to reenter light transmitted through the total reflection surface into the optical path conversion unit.