US 11,988,890 B2
Fixed focus lens
Shuo-Chieh Chang, Hsinchu Science Park (TW); and Yi-Hsueh Chen, Hsinchu Science Park (TW)
Assigned to YOUNG OPTICS INC., Hsinchu Science Park (TW)
Filed by YOUNG OPTICS INC., Hsinchu Science Park (TW)
Filed on Jan. 31, 2020, as Appl. No. 16/779,046.
Claims priority of application No. 108104182 (TW), filed on Feb. 1, 2019.
Prior Publication US 2020/0249418 A1, Aug. 6, 2020
Int. Cl. G02B 3/02 (2006.01); G02B 7/04 (2021.01); G02B 13/18 (2006.01); G02B 13/04 (2006.01); G02B 13/16 (2006.01)
CPC G02B 7/04 (2013.01) [G02B 13/18 (2013.01); G02B 13/04 (2013.01); G02B 13/16 (2013.01)] 19 Claims
OG exemplary drawing
 
1. A fixed focus lens, comprising:
a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens and a ninth lens arranged in order from a magnified side to a minified side, the first lens having at least one aspheric surface, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the eighth lens and the ninth lens comprising at least two compound lenses, wherein a total number of lenses with refractive powers of the fixed focus lens is no more than ten, a total number of plastic lenses of the fixed focus lens is no more than three, and a distance between any two lenses of the fixed focus lens keeps fixed during focusing; and
an aperture stop disposed between the third lens and the fourth lens, wherein a number of lenses with refractive powers disposed between the aperture stop and the magnified side is three or four, and the three or four lenses disposed between the aperture stop and the magnified side include a spherical lens with a positive refractive power and two aspheric lenses.