Projection lens and projection apparatus

Abstract

The invention provides a projection lens. The projection lens comprises a first lens group and a second lens group, wherein the first lens group is provided with negative diopter, is adjacent to an object side and comprises a first lens with negative diopter; and the second lens group is provided with positive diopter, is adjacent to an image side and comprises a second lens with positive diopter and a third lens with negative diopter; the second lens is disposed between the first lens and the third lens; the third lens is made of a dense flint glass material; the thermal variation parameter of the second lens is D0, and -3.0*e<-5><=D0<=-6.0*e<-7>.

Description

technical field [0001] The invention provides a projection lens and a projection device, especially a projection lens and a projection device that can automatically compensate for focus shift / defocus due to thermal shift. Background technique [0002] In order to save costs, common projectors on the market often use aspherical lenses in the projection lens. Aspheric lenses are usually made of plastic materials. Using a large number of aspheric lenses can easily lead to poor production yield of projection lenses. In addition, as the brightness of the projector increases, the plastic aspheric lens will have defects such as thermal variation and film removal. Among them, thermal shift refers to that after the projector has finished focusing, the temperature rises with the time of use, the optical engine (Optical Engine) metal casing produces thermal expansion and the optical components of the projection lens mounted on it produce refractive index changes, resulting in project...

AI Technical Summary

Problems solved by technology

Using a large number of aspheric lenses can easily lead to poor production yield of projection lenses

In addition, as the brightness of the projector increases, the plastic aspheric lens will have defects such as thermal variation and peeling

Among them, thermal shift refers to that after the projector has finished focusing, the temperature rises with the time of use, the optical engine (Optical Engine) metal casing produces thermal expansion and the optical components of the projection lens mounted on it produce refractive index changes, resulting in projection Lens defocus (Focus shift / Defocus), which affects the imaging quality of the projection lens

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