Ultra Short Throw Projection Lens

Abstract

The invention discloses an ultra-short-focus projection lens, which is used for imaging a first image displayed on a display into an enlarged second image. A first lens group for the first intermediate image, an aperture stop arranged at the imaging position of the first intermediate image, a second lens group for imaging the first intermediate image into a second intermediate image, and a second lens group for imaging the second intermediate image The intermediate image is reflected to form a mirror that magnifies the second image. The first lens group, the aperture stop and the second lens group have the same main optical axis. The transmittance of the ultra-short-throw projection lens is 0.2-0.25, the focal length is -2.9mm--3.2mm, and the offset of the first image relative to the main optical axis is greater than 120%. The invention can project a large image in a short distance and has high imaging quality.

Description

technical field [0001] The invention relates to the field of optical systems, in particular to an ultra-short-focus projection lens. Background technique [0002] The ultra-short-throw projection lens can effectively shorten the projection distance of the projector, and is an important solution for projecting large-size images at short distances on the market. [0003] There are three ways to shorten the focal length of the projection lens: refraction, reflection and hybrid. Refractive design lenses are all composed of lenses, including spherical lenses or aspheric lenses. Because the lens of this design has a large number of lens lenses and various types, the structure is often complicated, which is not conducive to manufacturing. Reflective lenses are all composed of reflectors, including spherical or aspheric reflectors. The reflectors can be convex, concave or plane reflectors, but the processing and detection of aspheric reflectors are more difficult. The mirror undou...

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