1. An imaging lens comprising:
a first lens group having a positive refractive power on an object side and including at least three positive lenses and at least two negative lenses; and
a second lens group having a negative refractive power on an image side and having a negative lens, the first and second lens groups arranged in this order from the object side with a widest air space in-between, wherein
in focusing an object from infinity to a close range, only the first lens group is moved to the object side and the second lens group is fixed relative to an image plane.
2. An imaging lens according to claim 1, wherein
the first and second lens groups are arranged to satisfy the following condition:
0.20<D1G-2GL<0.50
where D1G-2G is a distance from a lens surface of the first lens group closest to the image side to a lens surface of the second lens group closest to the object side when focusing on the infinite object, and L is a distance from a lens surface of the first lens group closest to the object side to the image plane when focusing on the infinite object.
3. An imaging lens according to claim 1, wherein
the first and second lens groups are arranged to satisfy the following conditions:
0.20<D1G-2GL<0.50
0.75<f1Gf<0.95
where D1G-2G is a distance from a lens surface of the first lens group closest to the image side to a lens surface of the second lens group closest to the object side when focusing on the infinite object, L is a distance from a lens surface of the first lens group closest to the object side to the image plane when focusing on the infinite object, f1G is a focal length of the first lens group, and f is a focal length of the entire lens system.
4. An imaging lens according to claim 1, wherein
the second lens group is configured to satisfy the following condition:
\u22126.5<(R2GF+R2GR)(R2GF\u2212R2GR)<\u22121.0
where R2GF is a curvature radius of an object-side surface of the negative lens, and R2GR is a curvature radius of an image side surface of the negative lens.
5. An imaging lens according to claim 1, wherein:
the first lens group comprises an aperture diaphragm, a front lens group arranged closer to the object side than the aperture diaphragm, and a rear lens group arranged closer to the image side than the aperture diaphragm;
the first lens group is configured to satisfy the following condition:
1.0<fG1Ff<2.0
where fG1F is a focal length of the front lens group and f is a focal length of the entire lens system.
6. An imaging lens according to claim 5, wherein:
the rear lens group includes a negative lens closest to the object side and having a concave surface on the object side; and
the rear lens group is configured to satisfy the following condition:
\u22122.5<R1RGFD1FG-1RG<\u22121.0
where R1RGF is a curvature radius of the concave surface of the negative lens and D1FG-1RG is a distance from a lens surface of the front lens group closest to the image to a lens surface of the rear lens group closest to the object side.
7. An imaging lens according to claim 5, wherein:
the rear lens group includes an aspheric surface shaped such that the closer to a periphery a portion is, the smaller a positive refractive power the portion has;
the rear lens group is configured to satisfy the following condition:
0.25<LS-ALS-I<0.55
where LS-A is a distance from the aperture diaphragm to the aspheric surface and LS-I is a distance from the aperture diaphragm to the image plane.
8. An imaging lens according to claim 5, wherein
the rear lens group comprises, from the object side, a negative lens with a concave surface on the object side, a positive lens with a convex surface on the image side, and a positive lens with a convex surface on the image side.
9. An imaging lens according to claim 1, wherein
the imaging lens is configured to satisfy the following condition:
1.2<Lf<2.0
where in focusing on the infinite object, L is a distance from a lens surface closest to the object side to the image plane and f is a focal length of the entire lens system.
10. An imaging lens according to claim 1, wherein
the imaging lens is configured to satisfy the following conditions:
0.50<Y\u2032f<0.75
0.50<tan(\u03b8Pmax)<0.70
where Y\u2032 is a maximal image height, \u03b8Pmax is an incidence angle of a principal beam reaching the maximal image height on the image plane, and f is a focal length of the entire lens system in focusing on the infinite object.
11. A camera comprising the imaging lens according to claim 1 as a photographic optical system.
12. A hand-held data terminal device comprising a camera function and the imaging lens according to claim 1 as a photographic optical system.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A system for exhaust gas purification, comprising, in the following order from an upstream side of an exhaust passage of an internal combustion engine:
a device for direct injection into an exhaust pipe;
an oxidation catalyst;
at least one of a catalyst for NOx removal and a catalyzed diesel particulate filter,
wherein a support of the oxidation catalyst is formed of a metallic material or a material having a specific heat not higher than that of a metallic material into a structure having a function of mixing exhaust gas;
an exhaust gas purification control unit which performs:
in-exhaust pipe direct injection in a predetermined first supply amount for raising a temperature of the oxidation catalyst when a first index temperature indicative of a temperature of the oxidation catalyst is above a first judgment temperature;
in-exhaust pipe direct injection in a predetermined second supply amount for raising a temperature of the exhaust gas when the first index temperature is above a second judgment temperature; and
in-exhaust pipe direct injection in a predetermined third supply amount for performing a corresponding one of regeneration by NOx removal and forced regeneration by particulate matter removal when a second index temperature indicative of a temperature of the at least one catalyst for NOx removal and the catalyzed diesel particulate filter reaches a third judgment temperature.
2. The system for exhaust gas purification according to claim 1, wherein the exhaust gas purification control unit employs:
a temperature at which the temperature of the oxidation catalyst becomes 200\xb0 C. as the first judgment temperature;
a temperature at which the temperature of the oxidation catalyst becomes 220\xb0 C. as the second judgment temperature; and
for the regeneration by NOx removal, a temperature at which the temperature of the catalyst for NOx removal becomes 250\xb0 C. as the third judgment temperature, or for the forced regeneration by particulate matter removal, a temperature at which the temperature of the catalyzed diesel particulate filter becomes 300\xb0 C. as the third judgment temperature.
3. A method of controlling a system for exhaust gas purification which includes, in the following order from an upstream side of an exhaust passage of an internal combustion engine, a device for direct injection into an exhaust pipe, an oxidation catalyst, and at least one of a catalyst for NOx removal and a catalyzed diesel particulate filter, comprising:
using a support of the oxidation catalyst formed of a metallic material or a material having a specific heat not higher than that of a metallic material into a structure having a function of mixing exhaust gas;
performing in-exhaust pipe direct injection in a predetermined first supply amount for raising a temperature of the oxidation catalyst when a first index temperature indicative of a temperature of the oxidation catalyst is above a first judgment temperature;
performing in-exhaust pipe direct injection in a predetermined second supply amount for raising a temperature of the exhaust gas when the first index temperature is above a second judgment temperature; and
performing in-exhaust pipe direct injection in a predetermined third supply amount for performing a corresponding one of regeneration by NOx removal and forced regeneration by particulate matter removal when a second index temperature indicative of a temperature of the at least one of the catalyst for NOx removal and the catalyzed diesel particulate filter reaches a third judgment temperature.
4. The method of controlling a system for exhaust gas purification according to claim 3,
wherein a temperature at which the temperature of the oxidation catalyst becomes 200\xb0 C. is employed as the first judgment temperature,
a temperature at which the temperature of the oxidation catalyst becomes 220\xb0 C. is employed as the second judgment temperature, and
for the regeneration by NOx removal, a temperature at which the temperature of the catalyst for NOx removal becomes 250\xb0 C. is employed as the third judgment temperature, or for the forced regeneration by particulate removal, a temperature at which the temperature of the catalyzed diesel particulate filter becomes 300\xb0 C. is employed as the third judgment temperature.