Classifications

• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
  • G02B6/44—Mechanical structures for providing tensile strength and external protection for fibres, e.g. optical transmission cables
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
  • G02B6/24—Coupling light guides
  • G02B6/36—Mechanical coupling means
  • G02B6/3608—Fibre wiring boards, i.e. where fibres are embedded or attached in a pattern on or to a substrate, e.g. flexible sheets
  • G02B6/3612—Wiring methods or machines
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
  • G02B6/24—Coupling light guides
  • G02B6/42—Coupling light guides with opto-electronic elements
  • G02B6/43—Arrangements comprising a plurality of opto-electronic elements and associated optical interconnections
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
  • G02B6/44—Mechanical structures for providing tensile strength and external protection for fibres, e.g. optical transmission cables
  • G02B6/4401—Optical cables
  • G02B6/4403—Optical cables with ribbon structure
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
  • G02B6/44—Mechanical structures for providing tensile strength and external protection for fibres, e.g. optical transmission cables
  • G02B6/4479—Manufacturing methods of optical cables
  • G02B6/448—Ribbon cables

Definitions

• the invention relates to a method and a device for applying an optical fiber to a substrate, in particular for making optical waveguide fiexfoils, i.e. flexible sheets having optical waveguides arranged therein or thereon, using optical fibers as the waveguides.
• the short range optical interconnect medium here presented consists of optical fibers mounted on a flexible substrate, i.e. an optical fiber flexfoil.
• optical flexfoil technique has been presented by the company AT&T, see U.S. patent No. 5,259,051 for Burack et al.
• This patent describes how optical fibers are routed using a rotatable wheel on a surface of a substrate coated with an adhesive.
• the rotatable wheel has three parallel grooves and is mounted at the lower end of a manipulator, i.e. a robot arm.
• the fiber is fed from a reel through a fiber guide to pass over a lower portion of the wheel in one of the grooves to be deflected at the wheel by an angle of about 45°.
• the wheel When the manipulator is moved down to the flat surface having an adhesive coating, the wheel will press the piece of optical fiber at its lower surface and partly inside the groove against the surface to make the fiber stick to the surface.
• the optical fiber is placed on the surface in one whole length of fiber.
• the substrate After placing the fiber on the surface, the substrate is cut to provide accessible fiber ends at the cutting lines, the whole length of fiber then being separated into a plurality of individual fiber pieces.
• the optical fiber can be severed after each interconnection made, i.e. after applying the optical fiber between e.g. a start tab and an end tab.
• the patent also describes how the optical fiber is encapsulated between two plastic foils, the surface having the adhesive coating being an inner surface of one of the foils. Before applying the other foil the optical fibers applied are encapsulated by a layer of a thermoplastic material.
• the problem to be solved by the invention is how to apply an optical fiber to a base flexfoil only at positions where it is needed for forwarding light and in an accurate manner with a good control of the applied fiber and with as small curvatures as possible with a minimum mechanical stress to the fiber during the application thereof.
• an optical fiber to a substrate, such as producing a flexfoil structure having optical waveguides located between two flexible plastics sheets which are laminated to each other, the substrate being one of the two foils to be laminated, this substrate is assumed to be coated with a suitable adhesive or at least to have a surface to which the optical fiber adheres when pressed against it.
• a supply of the optical fiber is located wound around a reel and the optical fiber is fed in a loose loop providing a fiber magazine from the reel to a collet or nozzle, giving the fiber located in front of or downstream the outlet of the collet a definite, accurately defined direction.
• the optical fiber is passed as freely extending fiber portion, not in contact with the substrate surface or anything else, to a hold-down means having a fixed bottom surface or pressing surface located at a small distance of the outlet of the collet.
• the hold-down means presses at its bottom or pressing surface the fiber against the surface of the substrate, the collet and its outlet then being located at some small distance from the substrate surface.
• the reel, collet and the holding-down means are moved so that the contact point at the substrate surface is moved along a desired path, where the optical fiber is to be placed.
• a fiber cutter is located upstream the collet and it can cut the fiber at the places where it is to end so that no loose fiber end portions are produced.
• a fiber feeder is provided behind the cutter to feed more fiber after it has been cut.
• the important features comprise firstly that in the laying-out-operation of the optical fiber the direction is defined by a device, the outlet of the collet, and the pressing operation of the fiber against the substrate is performed by a separate device, the hold-down means, or that the optical fiber is fed from the supply to contact, with a top side portion of the fiber, all the time the same bottom surface of the hold-down means and that simultaneously a bottom side portion of the fiber, which is opposite the top side portion, is pressed by the bottom surface to contact the surface of the substrate.
• the bottom surface is thus a fixed portion of the fixed hold-down means meaning that the fiber will all the time contact the same definite area of the bottom surface.
• the bottom surface is thus not rotatable or a portion of some rotatable body.
• the fiber is thus not guided in lateral directions of the fiber at the bottom or pressing surface of the hold-dow means, the lateral directions here being taken as directions parallel to the substrate surface and perpendicular to the longitudinal direction of the fiber.
• the bottom or pressing surface has no groove or any other guiding means, but it may be curved, as seen in the fiber direction, and straight, as seen in a direction perpendicular to the fiber direction along the substrate surface, or generally be part of a circular-cylindrical surface having its axis parallel to the substrate surface and a diameter of typically 10 - 20 mm.
• the direction of the fiber along the substrate surface when it is applied thereto, is only defined by the collet and the rigidity of the fiber between the outlet of the collet and the pressing surface.
• the distance between the outlet of the collet and the pressing surface is selected to be sufficiently small, so that the rigidity of the optical fiber will substantially maintain the direction given by the collet up to the pressing surface.
• the optical fiber when being feed from the outlet of the collet up to the pressing surface of the hold-down means will not be sharply deflected at the "pinch" between the pressing surface and the substrate surface. If it was too sharply deflected it could, owing to the bending and elastic forces in the fiber, easily loose its definite direction and slip away from the central portion of the pressing surface. Therefor, the free portion of fiber between the outlet of the collet and the pressing surface is made to form a small angle to the substrate surface, the angle being chosen to be as small as possible considering the necessary dimensions of the collet and the free portion of the fiber from the collet to the bottom surface.
• an angle of 5 - 15° preferably an angle of 5 - 10°
• the distance from the outlet of the collet to the substrate surface also called the height of the outlet, will then be equivalently small, e.g. about 0.2 - 0.5 mm, for a free portion of the fiber of about 3 - 5 mm, preferably substantially 4 mm between the outlet of the collet and the central point of the pressing surface. Since the width of the pressing surface or bottom surface of the hold-down means, as seen in the fibe direction, can suitably be about 3 - 4 mm, this means that the distance from the collet outlet to the most adjacent portion of the pressing surface is about 2 mm or generally 1.5 - 2 mm.
• the height of the collet outlet above the substrate surface should be as small as possible still allowing that the collet will not contact optical fibers earlier placed on and adhering to the substrate.
• the free portion of the fiber between the outlet of the collet and the pressing surface is selected to be as small as possible, considering that the collet should not touch earlier placed fibers and that the rigidity of the this portion should be sufficient to guide the fiber to the same central area at the lowest surface of the pressing means.
• a second feature comprises the cutting operation which can be performed at any place at the substrate and thus allows fiber pieces to start and end at any desired places.
• the magazine portion of the optical fiber between the supply and the contact point configured as a loosely hanging or suspended portion having a curvature allows a rapid feeding of the optical fiber at the contact point subjecting the fiber to a minimum of mechanical stress during the fiber-placing operation and in particular at bends of the laid- out fiber and at starts and stops.
• the lamination of the top foil could be performed before the cutting operation and in the lamination process then also there could be a risk a causing damage to the place fiber.
• the risk of such damage is virtually eliminated.
• the remaining risk of damage or malfunctioning will then reside in the activities made for connecting the optical fibers to external devices. However, such malfunctioning can only be detected by loss measurements on the individual fiber pieces in the finished flexfoil structure.
• the fiber routing method and device described herein have the capability of routing fiber for forming cross-overs even though the angle between the two fibers crossing each other is small. If the fiber routing device is equipped with a grooved wheel, as suggested by the cited first patent assigned to AT&T, low angle fiber cross-overs may be difficult to achieve.
• the fiber-carrying grooved wheel may be blocked by the adjacent fiber. If the wheel would be moved in the Z-direction or height direction away from the substrate surface, the fiber may loose track due to the small and shallow key way on the wheel and the elasticity of the fiber at the rather sharp bend at the wheel.
• this patent describes that the wheel is spring-loaded in order to allow cross-overs what will make sharp cross-overs even more difficult.
• the radius of the wheel in order to route fiber curvatures with small radii, the radius of the wheel must be small. Depending on the depth of the groove in the wheel, the radius of this wheel may need to be smaller than the smallest routing radius used. If the smallest radius used is close to the mechanical safe bending limit of approximately 5 mm for conventional glass fiber, that is only valid for short time periods of bending - for longer periods substantially larger bending radii are only allowed, the bending radius during routing due to the wheel may be harmful to the fiber.
• the placement definition and the actual attachment are separated into two parts by the collet and the sleigh or hold-down means instead of being provided by a single part performing simultaneously or integrated both functions, the grooved wheel. This avoids all problems associated with using a grooved wheel as described above.
• FIG. 1 is a perspective view of an apparatus for applying an optical fiber to a substrate
• FIG. 1 is a schematic cross-sectional view of the apparatus of Fig. 1 ,
• Fig. 3 is a cross-sectional view showing schematically a lower portion of a cutting tool
• Fig. 4 is a cross-sectional view showing schematically a lower portion of a feeding unit.
• Fig. 2 a schematic cross-sectional view of an apparatus for routing optical fiber 1 on a surface of a substrate 3 is shown, the apparatus being shown also in a perspective view in Fig. 1.
• the surface of the substrate is made to adhesive to an optical fiber to be applied such as by coating with a suitable adhesive or subjecting the surface to some other suitable treatment.
• a vertical flat house 5 is mounted on a robot arm 7 of a manipulator, not shown.
• a feeding collet 9 is attached at a low position of the house 5.
• a hold-down means or sleigh 11 is mounted at the lower end of the robot arm 7, so that the nozzle, outlet or mouth of the collet 9 is located at a small distance from and directed towards the bottom surface of the sleigh 11.
• the bottom surface has a part-cylindrical shape, the cylindrical surface thus being directed downwards and the axis of the part-cylindrical surface being perpendicular to the direction of a fiber passing through the collet 9 to the part-cylindrical surface and also horizontal and thus substantially parallel to the top surface of the substrate 3.
• the manipulator is capable of moving the arm 7 in parallel to the top surface of the substrate 3 located underneath the apparatus, the adhesive top surface being horizontal and extending in the X-Y-plane.
• the manipulator is also capable of moving the arm 7 in the vertical direction or Z-direction perpendicular to said surface and of rotating it in the ⁇ -direction about a vertical axis passing through the center of the generally vertical arm 7, through the contact point of a routed fiber drawn from the collet 9 and the bottom side of the sleigh 11.
• a reel 13 having the optical fiber wound thereon is mounted at the top edge of housing 5 .
• a motor unit 15 is attached to the reel 13 and has control means allowing the fiber to be automatically unwound from the reel 13. From the reel 13 the fiber is fed inside and in parallel to the vertical large surfaces of the house 5 in a specially designed path comprising first a loose, freely hanging or freely suspended loop 17, generally a free, non-straight portion having a curvature, and from that, as guided by a border 19 of the house 5, that projects laterally or in a horizontal direction from the large surfaces of the house 5, to the inlet of the feeding collet 9.
• a high precision fiber feeding unit 21 and a fiber cutting tool 23 are attached to the plate 5 behind or upstream the feeding collet 9. The fiber feeding unit 21 feeds the fiber or fiber-end region before and during the actual fiber routing.
• the house 5 thus has the shape of a basically inverted, triangular main body having a horizontal upper side and containing the fiber freely hanging loop 17.
• the reel 13 is attached to the front upper corner of the triangular shape.
• a channel projects for guiding the fiber to the feeding unit 21 , the channel being limited in the forward direction of the house by the border 19 and extending first in a vertical direction to finish in a curved portion having a forward bend to end in a small angle to the horizontal plane.
• a steel plate 24 connects the main triangular body of the house 5 and the channel portion for stabilizing the channel portion.
• a lower portion of the cutting tool 23 is shown in Fig. 3. It comprises a housing in which a cylindrical channel 31 is arranged for guiding the optical fiber 1 through the tool.
• a knife 33 is arranged in the housing in order to be moved, as driven by a suitable motor, not shown, see the arrow 34, in a direction perpendicular to the that of the channel 31 for cutting the optical fiber when required.
• a cleaning channel 35 is provided from the outside of the housing to the edge of the knife 33. Particles which can be formed in the cutting operation can be sucked out through this channel.
• the front mouth of the fiber channel 31 is connected to the nozzle 9, not visible in Fig. 3.
• a lower portion of the feeding unit 21 is shown in Fig. 4. It has a housing in which a cylindrical channel 41 is arranged for guiding the optical fiber 1 through the unit. Two rollers 43, acting on opposite sides of the optical fiber to be transported, are arranged inside the housing. The rollers 43 can rotate freely or be rotated by being driven by a motor, not shown, when required, for feeding the optical fiber in the channel 41 , both when introducing a new piece of optical fiber and after cutting the optical fiber in the cutting tool 23.
• the optical fiber is manually unwound from the reel 13 and positioned in the desired path inside the house 5, first in the loosely hanging loop 17 and then along a semi-circular path having its central point located highest, the border 19 and thus the channel portion of the house being configured correspondingly. From the semi-circular path the fiber is placed along a o vertical path and is then bent to a direction which is nearly horizontal and is therefrom inserted in the inlet of the fiber feeding unit 21.
• the fiber feeding unit 21 senses the inserted fiber end and feeds, by activating its motor acting on the rollers 43, a piece of fiber through the cutter 23 and the collet 9 and up to the central, lowest point of the bottom or pressing surface of the sleigh 11.
• the manipulator moves the arm 7 downwards, so that the sleigh 11 is moved towards the adhesive-made upper surface of the substrate 11 with the lowest points of its bottom surface forming a straight line parallel to the substrate surface. Then the bottom surface presses the fiber against the substrate surface, so as to make the fiber 1 adhere to the 0 adhesive surface of the substrate 11. The thickness of an adhesive coated on the substrate surface and/or the pressure are adjusted so that the bottom surface of the sleigh 11 never touches the adhesive and only the upper side of the fiber 1. The manipulator then moves the robot arm 7 in parallel to the upper surface of the substrate 3.
• the optical fiber 1 adheres to the substrate along a selected path determined by the 5 movement of the arm 7 in relation to the substrate 3.
• the friction or adhesive forces between the pressed-down fiber 1 and the adhesive surface causes the optical fiber to be automatically fed from the loose loop 17 inside the housing 5 and further through the feeding collet 9.
• the robot arm 7 is rotatable in the ⁇ - direction about its vertical central axis which passes through the contact point between the 0 sleigh 11 and the fiber 1 during the pressing operation.
• a change in the direction of the path of the fiber to be placed on the adhesive surface requires a rotation of the robot arm 7 as well as a change of the velocity of its movement in the X- and Y-directions.
• the amount of the rotation (movement in the ⁇ -direction) of the robot arm 7 in each instant is determined by the radius of the fiber path curvature.
• the cutting tool 23 is activated for cutting off the fiber by moving the knife 33.
• the robot arm 7 then continues its horizontal movement along a short additional path so that the fiber piece between the sleigh 11 and the edge of knife 33 in the cutting means 23 is expelled from the feeding collet 9 and is pressed on to the coated top surface.
• a piece of optical fiber has been placed at the coated surface in a desired path.
• the robot arm 7 is moved upwards, in the Z-direction from the top surface of the substrate 3.
• the robot arm 7 is free to move to a new starting point for another piece of optical fiber to be routed, i.e. to perform a movement in the X- and Y-directions.
• additional fiber is fed automatically by the feeding unit 21 by activating the motor acting on the rollers 43 through the cutting tool 23 and the feeding collet 9 in order to place the fiber end in a suitable start position centrally at the bottom surface of the sleigh 11.
• the robot arm 7 is then moved downwards, in the Z-direction towards the substrate surface, which causes the fiber at the lower surface of the sleigh 11 once again to adhere to the surface of the substrate 3. Now, a movement of the robot arm 7 in the X- and/or Y-directions causes new fiber to be routed, etc.
• a control and sensing unit 25 is mounted at a vertical side of the house 5 at the location of the loosely hanging fiber loop 17 and it is arranged to control the amount of fiber contained in this loop.
• the control and sensing unit 25 starts the motor 15 attached to the reel 13 for feeding a predetermined length of fiber from the reel 13 to restore the original shape of the loosely hanging loop 17.
• This can made by arranging e.g. two sensors 27, 29 such as photodetectors at different heights in the area of the loosely hanging loop 17.
• the upper sensor 27 signals when the loosely hanging loop has 17 been used sufficiently for feeding more fiber from the reel 13 and the lower sensor 29 signals that sufficient new fiber has been fed from the reel 13.
• a fiber crossing an already placed fiber may be routed even though the angle between the two fibers is small.
• the manipulator moves the robot arm 7 in the Z-direction upwards from the substrate surface at the starting point of the fiber crossover.
• the bottom surface of the sleigh 11 does not any more press the currently routed fiber against the substrate surface it moves in an oblique direction, i.e. simultaneously both in parallel with as well as perpendicular to, the adjacent fiber.
• the manipulator moves the arm 7 in the Z-direction towards the substrate surface which causes the fiber at the bottom surface of the sleigh 11 once again to adhere to the substrate surface.
• Attached to the robot, that carries the manipulator is a unit, not shown, that makes alignment marks on the substrate.
• the alignment marks are used as reference points in the coordinate system used by a control system using video cameras and controlling the manipulator in the same way as in automatic component mounting machines for e.g. surface mounting of electronic components.
• the alignment marks thus allow that a low accuracy is used when the substrate is placed in a fixture in the fiber routing apparatus.
• the fibers placed on a substrate as described above are then, for forming a flexfoil, encapsulated by a top substrate, not shown, placed on top of the fibers and of the substrate 11 and adhering to the fibers and the substrate, the substrates then usually comprising flexible plastic sheets.
• the flexfoil thus formed may then be subjected to a cutting operation for adjusting the shape of the flexfoil and for forming tongues, not shown, used for external optical connections. If the cutting machine is equipped with a vision system that locates the alignment marks on the substrate, the punching/cutting process may be performed using the internal coordinate system given by the alignment marks.
• the fiber routing technique here described allows a large number of fibers of arbitrary lengths to be routed on a substrate surface, i.e. arbitrary lengths in sense of several fibers having predetermined lengths or also one continuous fiber.
• the technique may be used for any kind of optical fiber, e.g. optical glass fibers and plastics or polymer optical fibers.

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Optics & Photonics (AREA)
• Mechanical Coupling Of Light Guides (AREA)
• Manufacture, Treatment Of Glass Fibers (AREA)
• Optical Couplings Of Light Guides (AREA)
• Light Guides In General And Applications Therefor (AREA)

Applications Claiming Priority (3)

Publications (1)

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Family Applications (1)

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• 1997
  • 1997-02-18 SE SE9700573A patent/SE9700573D0/xx unknown
  • 1997-03-26 TW TW086103852A patent/TW342462B/zh not_active IP Right Cessation
  • 1997-03-26 TW TW087111821A patent/TW416013B/zh active
• 1998
  • 1998-02-18 JP JP53567798A patent/JP2001511910A/ja active Pending
  • 1998-02-18 CN CN98802640A patent/CN1248328A/zh active Pending
  • 1998-02-18 AU AU62360/98A patent/AU6236098A/en not_active Abandoned
  • 1998-02-18 KR KR1019997007310A patent/KR20000071043A/ko not_active Application Discontinuation
  • 1998-02-18 EP EP98904511A patent/EP0970398A2/de not_active Withdrawn
  • 1998-02-18 WO PCT/SE1998/000285 patent/WO1998036306A2/en not_active Application Discontinuation
  • 1998-02-18 CA CA002281657A patent/CA2281657A1/en not_active Abandoned

Non-Patent Citations (1)

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