Optical waveguides – Miscellaneous
Reexamination Certificate
1999-11-12
2001-10-02
Healy, Brian (Department: 2874)
Optical waveguides
Miscellaneous
C383S105000, C383S049000
Reexamination Certificate
active
06298193
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATION
This application claims the priority of German Patent Application Serial No. 198 52 345.9, filed in Germany on Nov. 13, 1998, the subject matter of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
The present invention relates to a device for applying light conductive fibers onto substrates, which device has a mounting yoke, a holding device and a stamping device, as well as to a method for applying light conductive fibers, as is described in detail below.
Light conductive fibers, e.g. containing locally inscribed structures such as Bragg grids, can be used as optical sensors for measuring pressure, temperature or expansion. Among other things, they are distinguished by their EMI safety and chemical robustness, can be produced cheaply and can be adapted, based on the respective requirements, to the measuring variables to be detected. Fiber sensors of this type can be used for monitoring tasks in many areas of industrial technology. For this, the Bragg grid fiber sensors, for example, are either embedded in the material of the region to be tested or applied to the material surface.
So far, electro-optical modules and production methods are known from the U.S. references U.S. Pat. Nos. 4,997,253 and 4,237,474, where fibers are applied to a planar substrate surface. The U.S. Pat. No. 4,997,253 teaches installing the fiber on a T-shaped mounting aid to position it relative to an electronic component, e.g. a diode. Subsequently, the fiber is applied to the substrate base and is adjusted by means of a micro-manipulator acting upon the mounting aid and a soldering operation. According to the U.S. reference U.S. Pat. No. 4,237,474, this is done with the aid of several cube-shaped, glued-together mounting aids.
The mechanical dimensions present problems during the handling and processing, particularly when securing the sensors on a surface structure, because a sensor of this type can have a total length of several meters while its diameter is only approximately 100-200 &mgr;m. This results in considerable handling problems for the user, which normally require extensive adjustment procedures.
It is the object of the invention to specify a device and an advantageous method for applying light conductive fibers to substrate surfaces.
SUMMARY OF THE INVENTION
The invention involves a device for applying light conductive fibers onto substrates, which device comprises a mounting yoke, a holding device and a stamping device.
The holding device consists of a U-shaped base body having an outside region that arches upward and is provided with guide grooves as well as holders for installing the fibers in the device.
Guide grooves that completely accommodate the fibers extend in the region of the joint contact surface for the underside of the holding device and the substrate. The guide grooves installed in the outside region of the holding device are preferably V-shaped, wherein magnetic holders are used there to secure the fibers.
The stamping device, which comprises a stamp, a stamp neck and a stamp head, is located in the U-shaped die sink in the holding device and is arranged such that it can move in linear direction, relative to the holding device. A guide pin that is attached to the stamp head and extends inside a bore through the holding device serves as linear guide. This guide pin prevents a twisting of the stamping device, relative to the holding device. A spring that is fitted over the stamp neck is positioned between the base body and the stamp head, such that for the basic adjustment, the stamping device assumes a position that is slightly pulled back during the application, relative to the substrate surface. This position is determined by a detent on the stamp neck.
The stamp is provided with a rubber plate on the underside. This plate prevents damage to the plastic casing of the fiber to be applied. At least one separating foil is fitted over the underside of the rubber plate to prevent the fiber from adhering as a result of excess adhesive. Moreover, the stamp underside has either a level design or the center region contains an indentation, preferably in the sub-millimeter range, between the stamp and the rubber plate. As a result, undesirable stresses in the material arc prevented locally during the application.
The method for applying light conductive fibers to a substrate involves the following separate steps:
The holding device with the stamping device is fitted onto the mounting yoke, such that the stamp underside points upward.
The cleaned fiber is inserted into the device, is aligned and is secured.
Adhesive is applied to the fiber and the substrate over the predetermined gluing length.
The holding device, comprising the stamping device and the secured fiber, is removed from the mounting yoke.
The fiber is applied to the substrate surface by exerting pressure on the stamp head and remains in this position until the adhesive has hardened.
If necessary, an additional separating foil is loosely fitted over the stamp head between the fiber and the separating foil prior to exerting the pressure.
A particular advantage of the invention is that it ensures a precise positioning of fibers, particularly of functional units in fiber segments. Fiber breaks can be nearly ruled out as a result of the application method. Another advantage is the stress-free application in the form of fiber segments with functional units because the indentations on the stamp underside pointedly reduce the contact pressure in those regions.
The separating foils ensure that the device can be removed, following the hardening of the adhesive, so that no forces are exerted on the fiber as a result of excess adhesive that sticks.
REFERENCES:
patent: 4237474 (1980-12-01), Ladany
patent: 4950046 (1990-08-01), Hughes et al.
patent: 4997253 (1991-03-01), Enochs
patent: 5046800 (1991-09-01), Blyler, Jr. et al.
patent: 5155782 (1992-10-01), Kamir et al.
patent: 5194105 (1993-03-01), Nguyen
patent: 5259051 (1993-11-01), Burack et al.
patent: 5574811 (1996-11-01), Bricheno et al.
patent: 3815459A1 (1989-11-01), None
patent: 69311074T2 (1997-09-01), None
patent: 0665455A1 (1995-08-01), None
Staudigel Lothar
Trutzel Michael
Daimler-Chrysler AG
Healy Brian
Kunitz Norman N.
Venable
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