Projection zoom lens and projector
AssigneeRicoh Company, Ltd.
InventorTakashi Kubota
Life of this patent
Estimating the term…
Abstract
A projection zoom lens constituting a projection optical system of a projector, which projects an image displayed on a surface of an image display element on a projected surface, so as to magnify and display the image includes, in order from the projected surface side to the image display element side, a first lens group having a negative refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, a fourth lens group having a positive refractive power, and a fifth lens group, wherein a refractive power of the fifth lens group is weaker than the refractive power of the first lens group, the refractive power of the second lens group, the refractive power of the third lens group, and the refractive power of the fourth lens group.
Claims17
A projection zoom lens constituting a projection optical system of a projector, which projects an image displayed on a surface of an image display element on a projected surface, so as to magnify and display the image, the projection zoom lens comprising in order from the projected surface side to the image display element side:
- a first lens group having a negative refractive power;
- a second lens group having a negative refractive power;
- a third lens group having a positive refractive power;
- a fourth lens group having a positive refractive power;
- and
- a fifth lens group,
- wherein a lens group having a lens closest to the image display element side moves from the image display element side to the projected surface side when changing a magnification from a wide-angle to a telephoto end, and
- wherein the following condition is satisfied, where OALw is a distance (mm) from a lens surface on the projected surface side in a lens closest to the projected surface to a surface of the image display element when the image projected on the projected surface is focused, and Fw is a focal length (mm) of an entire projection optical system at the wide-angle end:
- 10.0<OALw/Fw<12.0.
A projection zoom lens constituting a projection optical system of a projector, which projects an image displayed on a surface of an image display element on a projected surface, so as to magnify and display the image,
- the projection zoom lens comprising in order from the projected surface side to the image display element side:
- a first lens group having a negative refractive power;
- a second lens group having a negative refractive power;
- a third lens group having a positive refractive power;
- a fourth lens group having a positive refractive power;
- and
- a fifth lens group, wherein
- a half-field angle ω satisfies the following condition,
- 39°<ω<45°.
A projection zoom lens constituting a projection optical system of a projector, which projects an image displayed on a surface of an image display element on a projected surface, so as to magnify and display the image, the projection zoom lens comprising in order from the projected surface side to the image display element side:
- a first lens group having a negative refractive power;
- a second lens group having a negative refractive power;
- a third lens group having a positive refractive power;
- a fourth lens group having a positive refractive power;
- and
- a fifth lens group,
- wherein a lens group having a lens closest to the image display element side moves from the image display element side to the projected surface side when changing a magnification from a wide-angle to a telephoto end, and
- wherein the fifth lens group includes, in order from the projected surface side, a negative lens, a positive lens, a negative lens and a positive lens.
Dependencies are inferred from the claim text.