JP2004252312A5 - - Google Patents

Claims (4)

A first lens having an aperture and a positive refractive power in order from the object side to the image surface side, a second lens having a meniscus positive refractive power with a concave surface facing the object side, and at least one bent surface The third lens having a negative refractive power having a spherical shape satisfies the following conditions (1) and (2), and the following conditions (3) for the object-side and image-side surface shapes of the second lens: An imaging lens characterized by satisfying
(1) 0.6 <f ₁ /f<2.5
(2) TL / f <1.9
(3) 0.2 <r ₅ / r ₄ <0.8
Where f: total focal length f ₁ of the entire lens system f ₁ : focal length of the first lens TL: distance from the stop to the image plane r ₄ : radius of curvature r ₅ on the object side of the second lens r ₅ : image side of the second lens Radius of curvature The imaging lens according to claim 1, wherein the following condition (4) is satisfied with respect to a surface shape of the first lens on the object side.
(4) 0.4 <r ₂ /f<1.3
Where r ₂ : radius of curvature of the first lens on the object side 3. The imaging lens according to claim 1, wherein the following condition (5) is satisfied with respect to the power of the third lens, and the following condition (6) is satisfied with respect to the object-side and image-side surface shapes of the third lens. An imaging lens characterized by that.
(5) −75 <f ₃ /f<−0.6
(6) 0.25 <r ₇ /f<0.8
Where f ₃ : focal length of the third lens r ₇ : radius of curvature on the image side of the third lens The imaging lens according to claim 2 or 3, wherein the following conditions (7) and (8) are satisfied.
(7) 0.7 <f ₁ /f<1.3
(8) 0.6 <r ₂ /f<1.0