Imaging optical system and image projection apparatus
AssigneeCanon Kabushiki Kaisha
InventorJunya Ichimura
Life of this patent
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Abstract
An imaging optical system includes, in order from an enlargement conjugate side to a reduction conjugate side, a first lens unit having a positive refractive power, a second lens unit having a positive refractive power, and a third lens unit. A distance between adjacent lens units varies in focusing from a far side to a near side. An intermediate image is formed inside the second lens unit. In focusing from the far side to the near side, the second lens unit moves to the reduction conjugate side, and the third lens unit moves to the enlargement conjugate side.
Claims7
An imaging optical system comprising in order from an enlargement conjugate side to a reduction conjugate side:
- a first lens unit having a positive refractive power;
- a second lens unit having a positive refractive power;
- and
- a third lens unit having a positive refractive power,
- wherein a distance between the second lens unit and the third lens unit varies in focusing from a far side to a near side,
- wherein an intermediate image is formed inside the second lens unit,
- wherein in focusing from the far side to the near side, the second lens unit moves to the reduction conjugate side, and the third lens unit moves to the enlargement conjugate side, and
- wherein the third lens unit consists of a single lens having a convex shape on the enlargement conjugate side.
An image projection apparatus comprising:
- an imaging optical system that includes, in order from an enlargement conjugate side to a reduction conjugate side, a first lens unit having a positive refractive power, a second lens unit having a positive refractive power, and a third lens unit having a positive refractive power, wherein a distance between the second lens unit and the third lens unit varies in focusing from a far side to a near side, an intermediate image is formed inside the second lens unit, in focusing from the far side to the near side, the second lens unit moves to the reduction conjugate side, and the third lens unit moves to the enlargement conjugate side, and the third lens unit consists of a single lens having a convex shape on the enlargement conjugate side;
- and
- a light modulation element disposed on the reduction conjugate side of the imaging optical system,
- wherein the imaging optical system is a projection optical system configured to project light from the reduction conjugate side onto a surface on the enlargement conjugate side.
Dependencies are inferred from the claim text.