Image pickup unit for endoscope
First Claim
1. An image pickup unit for endoscope consisting of an objective optical system and a solid-state image pickup device, and having a maximum field angle of 150°
- or larger,wherein said objective optical system is composed of spherical lens elements and plane parallel plates, and consists of a first lens unit which comprises a first meniscus lens element having a convex surface on the object side and having negative refractive power and has negative refractive power as a whole, a second lens unit which comprises at least a convex lens element and has positive refractive power as a whole and an aperture stop which is disposed between the first lens unit and the second lens unit, and satisfies the following conditions (1), (2) and (3);
0.7<
f/IH<
1
(1)
−
1.2<
f1/f<
−
0.7
(2)
0.9<
D/|f1|<
1.8
(3)wherein a reference symbol f represents a focal length of the objective optical system, a reference symbol IH designates a maximum image height in a display area of the solid-state image pickup device, a reference symbol f1 denotes a focal length of the first lens unit and a reference symbol D represents an equivalent air distance as measured along an optical axis from an image side surface of the first lens element in the first lens unit to the aperture stop.
4 Assignments
0 Petitions
Accused Products
Abstract
An image pickup unit which consists of an objective optical system and a solid-state image pickup device: the objective optical system being composed of a first negative lens unit comprising a first meniscus lens element having a convex surface on the object side and negative power, a second positive lens unit comprising a convex lens element and an aperture stop disposed between the first lens unit and the second lens unit and this image pickup unit having a small outside diameter, allowing a field angle to be changed little due to variations of parts and an assembling variation, and having a maximum field angle of 150° or larger.
76 Citations
18 Claims
-
1. An image pickup unit for endoscope consisting of an objective optical system and a solid-state image pickup device, and having a maximum field angle of 150°
- or larger,
wherein said objective optical system is composed of spherical lens elements and plane parallel plates, and consists of a first lens unit which comprises a first meniscus lens element having a convex surface on the object side and having negative refractive power and has negative refractive power as a whole, a second lens unit which comprises at least a convex lens element and has positive refractive power as a whole and an aperture stop which is disposed between the first lens unit and the second lens unit, and satisfies the following conditions (1), (2) and (3);
0.7<
f/IH<
1
(1)
−
1.2<
f1/f<
−
0.7
(2)
0.9<
D/|f1|<
1.8
(3)wherein a reference symbol f represents a focal length of the objective optical system, a reference symbol IH designates a maximum image height in a display area of the solid-state image pickup device, a reference symbol f1 denotes a focal length of the first lens unit and a reference symbol D represents an equivalent air distance as measured along an optical axis from an image side surface of the first lens element in the first lens unit to the aperture stop. - View Dependent Claims (2, 3, 4, 5, 6)
- or larger,
-
7. An image pickup unit for endoscope consisting of an objective optical system and a solid state image pickup device, and having a maximum field angle of 150°
- or larger,
wherein said objective optical system is composed of spherical lens elements and plane parallel plates, and satisfies the following conditions (4) and (5);
4f<
r1<
12f
(4)
|LH|≦
IH
(5)wherein a reference symbol f represents a focal length of the objective optical system, a reference symbol r1 designates a radius of curvature on a most object side surface of a first lens element, a reference symbol IH designates a maximum image height in a display area of the solid state image pickup device, and a reference symbol LH denotes a distance from a principal ray to be incident at said maximum image height to an optical axis on the most object side surface. - View Dependent Claims (8, 9, 10, 11, 12)
- or larger,
-
13. An image pickup unit for endoscope consisting of an objective optical system and a solid-state image pickup device, having a maximum field angle of 150°
- or larger and satisfying the following condition (6);
0.68<
IH2/IH1<
0.76
(6)wherein a reference symbol IH1 represents an image height of a ray which is incident on the objective optical system in a direction of 75°
relative to an optical axis and a reference symbol IH2 designates an image height of a ray which is incident on the objective optical system in a direction of 50°
relative to the optical axis. - View Dependent Claims (14, 15, 16, 17, 18)
- or larger and satisfying the following condition (6);
Specification