Image fiber

Abstract

An image fiber includes an image fiber body having a twisted portion which is formed by heating, softening, and twisting a portion of the image fiber body. The rate of twist in the twisted portion is made to be constant. Moreover, the rate of twist may preferably be set in a range from 1°/mm to 4000°/mm. In addition, the rate of twist at the beginning portion of the twisted portion and the rate of twist at the end portion of the twisted portion may preferably be set in a range from 3°/mm to 400°/mm. The twisted portion may be provided with a protective element.

Description

BACKGROUND OF THE INVENTION[0001]Priority is claimed under 35 U.S.C. § 119 to Japanese Patent application No. 2002-249139 filed Aug. 28, 2002, which is incorporated herein by reference.FIELD OF THE INVENTION[0002]The present invention relates to an image fiber in which a twisted portion is provided in order to rotate the orientation of a transmitted image, or to improve the quality of a transmitted image.BACKGROUND ART[0003]Image fibers, to which a twisting process is applied, are known in the art. One of the purposes of applying such a twisting process is to rotate the orientation of a transmitted image at the object side of an image fiber with respect to that at the observer's side thereof. Another purpose is to improve the quality of a transmitted image such as contrast, etc., as disclosed, for example, in Japanese Unexamined Patent Application, First Publication No. 2000-185931. Contrast in a transmitted image is improved because undesired light, which leaks from a core and pass...

AI Technical Summary

Benefits of technology

[0007]In view of the above problems, an object of the present invention is to provide an image fiber in which a twisted portion is provided so that a transmitted image is rotated without degrading the quality of the transmitted image.

Problems solved by technology

When the twisted portion is formed through the twisting process at an excessively large rate of twist, i.e., when the degree of twisting is excessive, deformation such as bending, elongation, etc., of cores that form pixels tend to become too great, and problems may be encountered in that defects such as dark spots are included in the transmitted image because light cannot pass through the cores.

Another defect is that contrast in the transmitted image is reduced because light leaking from some cores affects adjacent cores.

In particular, the above-mentioned defects tend to be significant in the cores disposed near the periphery of the image fiber because deformation due to twisting is greater in the cores near the periphery than in the cores disposed around the center of the image fiber.

The above-mentioned defects may occur where the degree of twisting is locally significant in the twisted portion.