To obtain a wetting detection sensor by which an optical transmission loss by a cause other than a wetting operation is exclused and by which a wetting position can be detected by a method wherein a plurality of wetting detection fibers in which every water- absorbing swelling layer is formed on every optical fiber core wire in which every coating layer is formed on every optical fiber strand are arranged in parallel and a common coating layer is provided on the outer circumference of every core wire and of the detection fibers.
A water-absorbing welling layer on the outer circumference of an optical fiber core wire is a resin layer which captures moisture in a wetted place and which absorbs the moisture so as to be swollen, a local bend or a microbend is generated in a strand due to a swelling operation, and an optical transmission loss is increased. A hydroxyl group is added to a photocuring resin as the swelling layer, and an epoxy acrylate resin or the like is used as a resin for a common coating layer on the outer circumference of the core wire and of a wetting detection optical fiber. The core wire is manufactured in such a way that the strand is coated with a resin composed mainly of an ultraviolet curing resin so as to be passed through an ultraviolet irradiation apparatus. The swelling layer at the detection fiber absorbs moisture when it is wetted, a side pressure is applied to the strand, the optical transmission loss is increased, the loss is detected so as to be compared, and the loss due to a true wetting operation is detected.
SHIONO TAKEO
ITO MITSUO
TANIMOTO HAJIME
OOSADA KOUJI
SEKI TOSHIKUNI
CHO HARUNARI
SHIRAISHI KEIKO
MURASE TOMOTAKA
