Zoom lens and image projection apparatus
AssigneeCanon Kabushiki Kaisha
InventorsJunya Ichimura, Kazuhiro Inoko, Saburo Sugawara
Life of this patent
Estimating the term…
Abstract
A zoom lens includes a negative lens unit having a negative refractive power, at least one positive lens unit having a positive refractive power, an intermediate lens unit including a stop, and at least one reduction side lens unit, in order from a magnification conjugate side to a reduction conjugate side, at least two magnification side movable lens units in the negative lens unit and the at least one positive lens unit, and at least one reduction side movable lens unit in the at least one reduction side lens unit are moved during zooming, and conditions of 0.9<(XT·βTb·φW)/(XW·βWb·φT)<1.1, 0.9<φW/φT<1.1, 0.8<(βTS·βTb)/(βWS·βWb)<1.2, and 1.4<fT/fW are satisfied.
Claims9
A zoom lens comprising, in order from a magnification conjugate side to a reduction conjugate side:
- a negative lens unit having a negative refractive power;
- at least one positive lens unit having a positive refractive power;
- an intermediate lens unit including a stop;
- and
- at least one reduction side lens unit,
- wherein at least two magnification side movable lens units out of the negative lens unit and the at least one positive lens unit, and at least one reduction side movable lens unit out of the at least one reduction side lens unit are moved during zooming, and
- wherein the following conditions are satisfied:
- 0.9<(XT·βTb·φW)/(XW·βWb·φT)<1.1
- 0.9<φW/φT<1.1
- 0.8<(βTS·βTb)/(βWS·βWb)<1.2
- 1.4<fT/fW
- where XW indicates an interval between a focal position at a wide angle end, of a front synthetic system constituted by lens elements arranged at the magnification conjugate side as compared with the stop, and the stop, βWb indicates an imaging magnification at the wide angle end, of a rear synthetic system constituted by lens elements arranged at the reduction conjugate side as compared with the stop, βWS indicates an imaging magnification of the intermediate lens unit at the wide angle end, φW indicates a diameter of the stop at the wide angle end, XT indicates an interval between a focal position at a telephoto end, of the front synthetic system, and the stop, βTb indicates an imaging magnification at the telephoto end, of the rear synthetic system, βTS indicates an imaging magnification of the intermediate lens unit at the telephoto end, φT indicates a diameter of the stop at the telephoto end, fW indicates a focal distance of a whole zoom lens system at the wide angle end, and fT indicates a focal distance of the whole zoom lens system at the telephoto end.
An image projection apparatus comprising:
- a light modulation device configured to modulate light;
- and
- a zoom lens configured to project the light from the light modulation device onto a plane to be projected,
- wherein the zoom lens comprises, in order from a magnification conjugate side to a reduction conjugate side:
- a negative lens unit having a negative refractive power;
- at least one positive lens unit having a positive refractive power;
- an intermediate lens unit including a stop;
- and
- at least one reduction side lens unit,
- wherein at least two magnification side movable lens units out of the negative lens unit and the at least one positive lens unit, and at least one reduction side movable lens unit out of the at least one reduction side lens unit are moved during zooming, and
- wherein the following conditions are satisfied:
- 0.9<(XT·βTb·φW)/(XW·βWb·φT)<1.1
- 0.9<φW/φT<1.1
- 0.8<(βTS·βTb)/(βWS·βWb)<1.2
- 1.4<fT/fW
- where XW indicates an interval between a focal position at a wide angle end, of a front synthetic system constituted by lens elements arranged at the magnification conjugate side as compared with the stop, and the stop, βWb indicates an imaging magnification at the wide angle end, of a rear synthetic system constituted by lens elements arranged at the reduction conjugate side as compared with the stop, βWS indicates an imaging magnification of the intermediate lens unit at the wide angle end, φW indicates a diameter of the stop at the wide angle end, XT indicates an interval between a focal position at a telephoto end, of the front synthetic system, and the stop, βTb indicates an imaging magnification at the telephoto end, of the rear synthetic system, βTS indicates an imaging magnification of the intermediate lens unit at the telephoto end, φT indicates a diameter of the stop at the telephoto end, fW indicates a focal distance of a whole zoom lens system at the wide angle end, and fT indicates a focal distance of the whole zoom lens system at the telephoto end.
Dependencies are inferred from the claim text.