US 12,298,596 B2
Optical system and projector
Hitoshi Hirano, Suwa (JP); Yasuyuki Kiyama, Suwa (JP); Koji Shiokawa, Suzaka (JP); and Yuta Ito, Azumino (JP)
Assigned to SEIKO EPSON CORPORATION, Tokyo (JP)
Filed by SEIKO EPSON CORPORATION, Tokyo (JP)
Filed on Aug. 3, 2022, as Appl. No. 17/880,185.
Claims priority of application No. 2021-127323 (JP), filed on Aug. 3, 2021.
Prior Publication US 2023/0054195 A1, Feb. 23, 2023
Int. Cl. G02B 9/62 (2006.01)
CPC G02B 9/62 (2013.01) 9 Claims
OG exemplary drawing
 
1. An optical system comprising:
a first lens having negative refractive power; a stop; a second lens having positive refractive power; an aperture stop; a third lens having positive refractive power; a fourth lens having negative refractive power; a fifth lens having positive refractive power; and a sixth lens having positive refractive power with the first to sixth lenses sequentially arranged from a magnifying side toward a demagnifying side,
wherein the third lens and the fourth lens are bonded to each other into a doublet,
the doublet has negative refractive power,
one of the fifth lens and the sixth lens is made of plastic and has aspherical surfaces on opposite sides, and another of the fifth lens and the sixth lens is made of glass,
a portion on the demagnifying side of the sixth lens is a telecentric portion, and
Conditional Expression (1) below is satisfied,
SD12/SD2<0.9  (1)
where SD12 represents an effective radius of the stop, and SD2 represents an effective radius of the second lens.