Projection zoom lens and projection type display apparatus

Abstract

The invention provides a projection zoom lens, which has nine lenses in five groups. The first group is set as simple structure with the F value of wide-angle end lower than 1.7 and field angle more than 55 degree, which can well modifies various aberration and is cheap and smart. The projection zoom lens includes a first lens group (G) having a negative reflecting power and a second to fifth lens groups (G-G) each having a positive reflecting power are provided in the order from the reduction side. Nine lenses are distributed in a manner that the first lens group (G) has one lens, the second lens group (G) has one lens, the third lens group (G) has two lenses, the fourth lens group (G) has four lenses and the fifth lens group (G) has one lens. Since the second lens group (G), the third lens group (G) and the fourth lens group (G) are moved at the time of the power-varying operation, various kinds of aberrations may be made despite of simple configuration. Furthermore, the first lens group (G) is an aspherical lens which concave surface is directed to the reduction side.

Description

technical field [0001] The present invention relates to a compact projection zoom lens with a structure of 5 groups and 9 elements loaded in a projection display device and the projection display device loaded with the projection zoom lens. A zoom lens for projection and a projection display device that are used especially when light beams of image information from a light valve such as a transmissive or reflective liquid crystal display device or a DMD (Digital Micromirror Device) display device are enlarged and projected onto a screen from the front side. Background technique [0002] In recent years, projection display devices using light valves, such as liquid crystal display devices and DMD display devices, have been widely used. In particular, a structure in which each illumination light is modulated by using three light valves and corresponding to the illumination lights of RGB3 primary colors is widely used. , Combining the light modulated by each light valve with a ...

AI Technical Summary

Problems solved by technology

[0009] However, although the projection zoom lenses described in the above-mentioned Patent Document 1 and the above-mentioned Patent Document 2 are relatively small, they have a dark F value of 2.0 or more at the wide-angle end, and a narrow field of view at the wide-angle end of 50° or less.

[0010] Furthermore, the projection zoom lens described in Patent Document 3 is bright with an F value of 1.6 at the wide-angle end and wide-angled at a field angle of 55° at the wide-angle end, but the first lens group with the largest lens outer diameter Using three lenses makes it difficult to reduce the size and weight of the entire lens system

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