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Optical element, polarization illumination device, and projector

a technology of polarization illumination and optical elements, applied in the direction of polarising elements, lighting and heating apparatus, instruments, etc., can solve the problems of reducing the efficiency with which light is used, ineffective light-incoming areas ua are areas, etc., and achieve the effect of brighter image and high efficiency

Inactive Publication Date: 2006-08-22
SEIKO EPSON CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention provides an optical element that can more efficiently use the light of a polarization illumination device or a projection display apparatus. This is achieved by using two polarization conversion element arrays that convert polarized light with random polarization directions to one type of polarized light. The optical element has a predetermined space between the two arrays, and the light beams incident upon the first array are converted into a predetermined type of polarized light beam, while the light beams incident upon the second array are not converted. This allows the effective polarized component of the light to be utilized, increasing the efficiency with which the light is used. Additionally, dummy regions may be formed to mitigate the issue of light beams incident upon the end of the arrays not being effectively used. The construction also allows for the use of fewer polarization separating surfaces and reflecting surfaces, reducing the cost of the optical element.

Problems solved by technology

On the other hand, the ineffective light-incoming areas UA are areas of the light-incoming surface of the polarization conversion element where the incident light beams leave the polarization conversion element after being converted into undesired polarized light beams.
In this case, the aforementioned outgoing p-polarized light beams are not used, thereby reducing the efficiency with which light is used.

Method used

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  • Optical element, polarization illumination device, and projector
  • Optical element, polarization illumination device, and projector
  • Optical element, polarization illumination device, and projector

Examples

Experimental program
Comparison scheme
Effect test

first embodiment

[0055]B:

[0056]FIG. 4 is a front view showing the light-incoming surface of the optical element 300 of the first embodiment. FIG. 5 is a rear view of the light-outgoing surface thereof. FIG. 6 is a sectional view taken along line A—A′ of FIG. 5. FIG. 7 is a side view of the optical element 300.

[0057]In the optical element 300, two polarization conversion element arrays 320a and 320b are affixed to the flat light-outgoing surface of the light-gathering focus lens array 310, using an optical adhesive. The two polarization conversion element arrays 320a and 320b are arranged opposite to each other, and are disposed on the left and right sides of a center CL in the horizontal direction of the focus lens array 310 so as to be spaced apart by a predetermined space Cp which is described later. Like the first optical main element 200 (of FIG. 2), the focus lens array 310 contains substantially rectangular focus leaves 311 in a matrix arrangement with M rows and 2N columns. Thus, there are N ...

second embodiment

[0070]C.

[0071]FIG. 12 is a diagram illustrating an optical element of the second embodiment. The middle portion of FIG. 12 shows the distribution of the quantities of light illuminating the light-incoming surface of a polarization conversion element array 320a, after gathering of the light by each of the lenses La to Ld of the lens array 310 in a structure such as that of the polarization illumination device 50 (FIG. 1). In general, the intensity Ia of the light gathered by the lens La nearest the optical axis is the strongest, while the intensity of the light gathered by the lens furthest from the optical axis is weakest. In FIG. 12, the intensity Id of the light gathered by the fourth lens is the weakest. The light quantity distribution shifts from its associated lens center towards or away from the optical axis starting from a certain lens position (the position of the third lens Lc in FIG. 12), so that for the light quantity distributions of the lenses La to Ld, the closer the l...

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Abstract

Two polarization conversion element arrays are disclosed. Each polarization conversion element array is composed of a plurality of polarization conversion elements for converting light incident upon the polarization conversion element array to a linearly polarized light beam with a predetermined polarization direction. The plurality of polarization conversion elements are disposed opposite to each other with a predetermined space provided between at about the center of the light-outgoing surface of a lens array in the direction of arrangement. Of the light beams (s-polarized+p-polarized light beams) gathered by the lens array, light beam that is not incident upon the polarization conversion element and passes through the predetermined space is a light beam including a predetermined polarized light beam (s-polarized light beam) that is primarily made to leave the array 320a and an ineffective polarized light beam (p-polarized light beam). Of the light passing through and leaving the space, the required polarized light beam alone can be made to leave as an effective light beam by providing a polarization plate or the like at the light-outgoing side of the space.

Description

[0001]Notice: More than one reissue application has been filed for the reissue of U.S. Pat. No. 5,978,136. The reissue applications are application numbers 09 / 985 / 390 (the present application), Reissue Application No. 11 / 066,243 filed Feb. 25, 2005, and Reissue Application No. 11 / 403,242 filed Apr. 13, 2006, all three of which are reissue applications of Pat. No. 5,978,136.BACKGROUND OF THE INVENTION[0002]1. Field of Invention[0003]The present invention relates to an optical element for converting light incident thereto to a predetermined polarized light beam, as well as a polarization illumination device and a projection display apparatus using the same.[0004]2. Description of Related Art[0005]In order to increase the efficiency with which light is utilized to provide a bright display, illuminating optical systems of projection display apparatuses make use of a method that converts polarized light with random polarization directions to polarized light with one polarization directio...

Claims

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Application Information

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Patent Type & Authority Patents(United States)
IPC IPC(8): G02B5/30G02B27/28G03B21/00G02F1/13G02F1/1335G02F1/13357H04N9/31
CPCG02B27/283G02B27/285H04N9/3105H04N9/3167
Inventor OGAWA, YASUNORIYAJIMA, AKITAKAUSHIYAMA, TOMIYOSHI
Owner SEIKO EPSON CORP