Pantoscopic zoom lens for projection and projection type display device

Abstract

The invention provides a projection pancratic pantoscope which structure is compact and which half view angle is over 45 DEG on the wide angle end, and a projection-type display device carrying the projection pancratic pantoscope. From the amplification side, the invention comprises: a set of focusing lenses (G<1>) having fixed negative refraction force during varying the power; three sets of room movable lenses (G<2>-G<4>) capable of independently moving during varying the power; a set of lenses (G<5>) which has fixed positive refraction force during varying the power for fixing the pupil position; and the reduction side is telecentric. The set of focusing lens (G<1>) is composed of four pieces of negative lenses (L<1>-L<4>) which are arranged continuously from the most amplification side, wherein, both sides of the first lens (L<1>) and the reduced side of the fourth lens (L<4>) are configured as aspheric surface.

Description

technical field [0001] The present invention relates to a zoom lens used as a projection lens of a projector device, etc., and particularly relates to enlarging and projecting an original image formed by a light valve such as a liquid crystal display element or a DMD (digital micro mirror device: digital micro mirror device) on a A wide-angle zoom lens for projection on a screen, and a projection display device equipped with the wide-angle zoom lens for projection. Background technique [0002] A so-called front projection type projector that projects an image onto a screen in front of the device has been widely used in recent years for school education, corporate training, presentations, and the like. [0003] A projection lens mounted on such a front projection type projection device is required to have a variable magnification function (zoom function), have a compact configuration, and have a wide viewing angle in consideration of portability of the device and compatibili...

AI Technical Summary

Problems solved by technology

[0008] Among fixed-magnification projection lenses mounted on rear projector devices, etc., lenses with a half angle of view of 45 degrees or more are known. It is difficult to maintain good optical performance from the wide-angle end to the telephoto end, and it is particularly difficult to maintain axial aberrations such as spherical aberration common to the viewing angle (image height), and distortion or curvature of field that vary with the viewing angle. The balance of off-axis aberrations, and it is difficult to make good corrections for the above-mentioned aberrations

In addition, there is also the problem that compaction is difficult due to the large lens system of the lens group arranged on the magnification side, and it has not been realized.

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