US 12,072,617 B2
Light source optical system, light source device, light source unit, and image display apparatus
Makoto Hirakawa, Tokyo (JP); Yohei Takano, Kanagawa (JP); and Kasumi Nakamura, Kanagawa (JP)
Assigned to RICOH COMPANY, LTD., Tokyo (JP)
Filed by Ricoh Company, Ltd., Tokyo (JP)
Filed on Apr. 21, 2023, as Appl. No. 18/137,445.
Application 18/137,445 is a continuation of application No. 17/533,119, filed on Nov. 23, 2021, granted, now 11,669,004.
Claims priority of application No. 2020-196706 (JP), filed on Nov. 27, 2020; and application No. 2021-139519 (JP), filed on Aug. 30, 2021.
Prior Publication US 2023/0251559 A1, Aug. 10, 2023
Int. Cl. G03B 21/20 (2006.01); F21V 8/00 (2006.01); G02B 6/10 (2006.01); G02B 6/27 (2006.01); G02B 27/10 (2006.01); G02B 27/28 (2006.01)
CPC G03B 21/204 (2013.01) [G02B 27/1066 (2013.01); G02B 27/283 (2013.01); G03B 21/2066 (2013.01); G03B 21/208 (2013.01); G02B 6/0056 (2013.01); G02B 6/105 (2013.01); G02B 6/2773 (2013.01)] 18 Claims
OG exemplary drawing
 
1. A light source optical system comprising:
a first optical system to guide a first light beam having a first wavelength emitted from a light source to a wavelength conversion element;
the wavelength conversion element to convert the first light beam into a second light beam having a second wavelength different from the first wavelength, and emit the second light beam; and
a second optical system through which the second light beam emitted from the wavelength conversion element passes, the second optical system including a light guide element to guide a portion of the second light beam from one end surface of the light guide element to the other end surface of the light guide element to separate the portion of the second light beam from the second light beam,
wherein the light guide element includes:
a first surface,
a second surface that the portion of the second light beam enters,
a third surface, and
a fourth surface,
wherein a projection area of the second surface is smaller than that of the first surface, the projection area on a plane perpendicular to an optical axis of the second optical system,
wherein a portion of the second light beam enters the light guide element from the second surface, propagates through the light guide element while repeating total internal reflection multiple times, and exits the light guide element from the fourth surface,
wherein a projection area of the fourth surface on the plane perpendicular to the optical axis of the second optical system is smaller than a projection area of the third surface,
wherein in a direction perpendicular to the optical axis of the second optical system, both the second surface and the fourth surface are within a range of the optical path through which the second light beam passes, and
wherein a magnitude of the second light beam passing through the light guide element includes a magnitude of light entering the first surface which exits the third surface and a magnitude of light entering the second surface and exiting the fourth surface.