Projecting optical system
AssigneeCanon Kabushiki Kaisha
InventorSaburo Sugawara
Life of this patent
Estimating the term…
Abstract
A projecting optical system includes, in order from the side of a screen, a first lens unit of positive refractive power of retrofocus type and a second lens unit composed of one positive lens, wherein parameters of the projecting optical system are determined such that an off-axial principal ray crosses an optical axis between the first lens unit and the second lens unit, and the following condition is satisfied: 0.2<D2f/f<0.95 (1) where D2f is a distance from a vertex of a lens surface facing the screen side of the second lens unit to an original-image display plane, and f is a focal length of the projecting optical system.
Claims22
A projecting optical system comprising, in order from a first conjugate point of a longer distance, a first lens unit of positive refractive power of retrofocus type and a second lens unit consisting of one positive lens, wherein parameters of said projecting optical system are determined such that an off-axial principal ray crosses an optical axis between said first lens unit and said second lens unit, and the following condition is satisfied:
- 0.2<D2f/f<0.95 (1)
- where D2f is a distance from a vertex of a lens surface facing the first conjugate point of said second lens unit to a second conjugate point of a shorter distance, and f is a focal length of said projecting optical system.
A projecting optical system comprising, in order from a first conjugate point of a longer distance, a first lens unit of positive refractive power of retrofocus type and a second lens unit consisting of one positive lens, wherein parameters of said projecting optical system are determined such that an off-axial principal ray crosses an optical axis between said first lens unit and said second lens unit, and said second lens unit is provided with at least one aspheric surface.
A projecting optical system comprising:
- a light source;
- a first optical element having a diffracting portion for separating light from said light source into three color light beams, and a total reflection surface for totally reflecting one color light beam of the three color light beams separated out by said diffracting portion;
- a second optical element for totally reflecting one of the other color light beams which have exited from said first optical element and for transmitting the remaining color light beam;
- and
- image modulating elements respectively disposed in optical paths of the three color light beams having exited from said first optical element and said second optical element.
Dependencies are inferred from the claim text.