GB2182326A - Cutting optical fibre ribbon - Google Patents

Abstract

A manual device for bending an optical fibre ribbon, which has been cut to effect a transverse score in each optical fibre, to cause the fibres to break with end faces that are flat and lie in a common plane, comprises a convexly curved table 12 and, on opposite sides of the table, clamping means 9 and guide means is for clamping and guiding the optical fibre ribbon across the table. The table 12 and clamping and guide means are interconnected in such a way that the table is constrained to move towards or away from the clamping and guide means in a direction normal to the optical fibres and is urged away from the clamping and guide means by a spring. By moving the table 12 between the clamping means 9 and guide means 19 against the action of the spring 16, the convexly curved surface 14 of the table engages and bends the optical fibre ribbon about an axis normal to the axes of the optical fibres to cause the fibres to break. <IMAGE>

Description

SPECIFICATION Cutting optical fibre ribbon This invention relates to optical fibre ribbon ofthe kind comprising a plurality of optical fibres arranged side by side with their axes lying in a substantially common plane and embedded in an elongate body of plastics material.

When effecting a splice between optical fibres of an optical fibre ribbon ofthis kind and optical fibres ofanother optical fibre ribbon ofthe same kind, in orderto ensure optimum light coupling efficiency in each optical fibre joint or, in other words to keep light losses at each joint as low as possible, it is desirable that the end faces of each pair of optical fibres to be jointed be substantially flat and lie in planesradialto the axes of the fibres and that end faces of the optical fibres of each optical fibre ribbon lie in a substantially common plane.

In one known method of providing optical fibres of an optical fibre ribbon of the kind described with end faces that are substantially flat and lie in a substantially common plane radial to the axes of the fibres, a length of optical fibre ribbon is supported on a sub stantially smooth surface; a rectilinear cut is effected substantially normal to the axes ofthe optical fibres across the whole transverse width of the optical fibre ribbon to a depth sufficient to effect a transverse score in each optical fibre; and thereafter the optical fibre ribbon is bent about an axis extending substantially normal to the axes ofthe optical fibres to such an extent that the fibres of the ribbon cleave to form on the fibres end faces which are substantially flat and lie in a substantially common plane radial to the axes of the fibres.

It is an object ofthe present invention to provide, for use in the aforesaid method, an improved manual device for bending an optical fibre ribbon of the kind described about an axis extending substantially normal to the axes ofthe optical fibres.

According to the invention the improved manual device comprises a table which has a substantially smoothsurfaceofconvexlycurvedform and, on each of two opposite sides of the axes containing the centres of curvature of the convexly curved surface ofthetable, one of a pair of clamping and guide meansforclamping and guiding across the table on optical fibre ribbon of the kind described, which has in each of its optical fibres a transverse score which is substantially normal to the axis of the optical fibre, the transverse scores in the optical fibres lying in a substantially common plane, in such a way that the transverse scores overlie and are remote from the convexly curved surface of the table and the optical fibres ofthe ribbon lie substantially normal to the axis containing the centres of curvature of the con- vexly curved surface ofthe table, the table and the pairs of clamping and guide means being inter connected in such awaythatthetable, orthe pairsof clamping and guide means, is orare constrainedto movetowardsorawayfromthepairsofclamping and guide means, orthetable, in a direction substan tially normal tothe optical fibres ofthe ribbon and to said axis containing the centres of curvature ofthe convexlycurvedsurfaceofthetableandisorare urged away from the pair of clamping and guide means, or the table, by associated spring means, the arrangement being such that, after an optical fibre ribbon has been so clamped and guided by said clamping and guide means, relative movement can be effected between the table and the pairs of clamping and guide means against the action of said associated spring means to cause the convexly curved surface of the table to engage and bend the optical fibre ribbon about an axis extending substantially normal to the axes of the optical fibres to such an extent that the fibres ofthe ribbon cleave to form on the fibres end faces which are substantially flat and lie in a common plane radial to the axes ofthe fibres.

Preferably, at least one surface ofthe clamping means which will be contiguous with an optical fibre ribbon, and the convexly curved smooth surface of the table, are made of a material which is sufficiently resilient, or which is rendered sufficiently resilient, to accommodate the shock of any optical fibre breaking and thereby limit the extent to which such a shock will be imparted to a neighbouring optical fibre. It is preferred to employ, for this purpose, a rubber-like material of about 60 shore hardness.

Each pairofclamping and guide means preferably is mounted on a substantially rigid base and the table preferably is slidably mounted in a chamber between the pairs of clamping and guide means and is urged away from the pairs of clamping and guide means by an associated spring. Alternatively, the table may be mounted on a substantially rigid elongate base and each pair of clamping and guide means may be slidably mounted on a shaft upstanding from the base on one side ofthetable and urged awayfromthe base by a coil spring positioned on the shaft.

Each of the clamping means preferably comprises a bed having a substantially smooth fiat surface and, for clamping an optical fibre ribbon on the bed, a pivotally mounted lever mechanism which can be snapped into the closed or clamping position and which has a clamping pad of substantially resilient material. Alternatively, the pivotally mounted lever mechanism may be urged into the closed or clamping position by an associated spring.

In a preferred embodiment, the beds of the clamping means may be integral parts of an arm which extends laterally across the table in a direction substantially normal to the axis ofthe centres ofcurvature of the convexly curved surface, the chamber in which thetable is slidably mounted opening into the surface of the arm between the clamping means.

To provide for effecting movement of the table relativetothe pairs of clamping and guide means against the action of said associated spring, preferably the chamber extends through and opens intotheopposite surface of the arm so that the table can be moved towards the pairs of clamping and guide means by manual pressure; alternatively, the undersurface ofthetable in the chamber may be engaged by a cam controlled by an operating lever pivotally mounted on a side wall of the arm.

The guide means on each of said two opposite sides of the table preferably comprises the riser of a step on the bed of the clamping means, which step extends substantially normal to the axis ofthecen- tres of curvature of the convexly curved smooth su rface of the table.

The improved manual device preferably comprises a component part of a hand tool for effecting a transverse score in each optical fibre of an optical fibre ribbon of the kind described, which hand tool comprises at least two elongate members pivotally connected together at or near one oftheir ends about an axis extending transverse to the members, one of the members or at least one ofthe members being urged away from the other member or members by associated spring means; an improved manual device as hereinbefore described mounted on one of said members art a position remote from said pivotal axis; and an elongate cutter which is associated with the table of said manual device and is mounted on the other or anther ofthe members and which has a rectilinear cutting edge which extends substantially parallel to the axis containing the centres of curvature ofthe convexly curved smooth surface of the table.

Preferably, the improved manual device of the present invention constitutes a component part ofthe improved hand tool for effecting a transverse score in each optical fibre of an optical fibre ribbon ofthe kind described as described and claimed in the specification of our co-pending British Patent Application No: 8430922. This improved hand tool may incorporate any one or more of the optional features described and claimed in the specification ofthe aforesaid co-pending patentapplication.

The invention is further illustrated by a description, byway of example, of a preferred hand tool for effecting a transverse score in each optical fibre of an optical fibre ribbon ofthe kind described, which hand tool incorporates a preferred manual deviceforben- ding the optical fibre ribbon about an axis normal to the transversely scored optical fibres, with reference to the accompanying drawings, in which Figure lisa sectional side view of the hand tool shown with the rectilinear cutting edge ofthe elongate cutter in the position it will be when effecting a rectlinearscore in each optical fibre, and Figure2 is a front end view of thetool.

Referring to the drawings, the improved hand tool comprises three elongate members 1,2 and 3 exten ding side by side and interconnected together near one of their neighbouring ends by an end wall 4. One outer elongate member 1 is fixed to the end wall 4 and the other outer elongate member 3, which is of inverted channel-shaped cross-section, is pivotally connected to the end wall about an axis 5 transverse to the members.

At the end of the outer elongate member 1 remote from the end wall 4 is an arm 6 which extends late rally on opposite sides ofthe member and which has an upper smooth flat surface 7. Mounted on the late- rally extending arm 6 on opposite sides of the central transverse axis ofthe arm are clamping means 9for clamping an optical fibre ribbon on the smooth surface 7 ofthe arm. The clamping means 9 comprises a pivotally mounted lever mechanism 10 which can be snapped into the closed or clamping position and which has a pad 11 of rubber-like material of about 60 shore hardness and the smooth flat surface 7 ofthe laterally extending arm 6, the pad serving to clamp an optical fibre ribbon against the smooth surface of the arm.Atable 12which has a smooth surface 14of convex form of rubber-like material, the centres of curvature of the convex surface lying on an axis normal to the pivotal axis 5 of the elongate member 3, isslidably mounted in a chamber 15 extending through and opening into the upper surface 7 of the arm 6 between the clamping means 9 and is urged away from the clamping means by a coil spring 16.

The chamber 15 also opens into the undersurface 17 of the arm 6 to provide, as will be explained,for movement of the table 12 with respect to the clamping means 9.

Adjacent each clamping means 9 on the uppersur face 7 of the laterally extending arm 6 is a step 19 which extends normallyto the axis of the centres of curvature of the convexly curved smooth surface 14 of the table 12 and whose riser constitutes guide means for an optical fibre ribbon.

The elongate member 2 is pivotally connected to the end wall 4 about axis 5 and, between its ends, the elongate member is connected to the outer elongate member 3 by a screw 21 which depends from the member 3, passes through a hole 22 in the member2 and which, on the side of the member 2 remote from the member 3, carries a coil spring 23 positioned be tweenthe member2 and a nut 24, which spring urges the member2towardsthe member 3. Pivotal movement of the elongate member 2 is restrained by a leaf spring 26 which is secured to the member and which bears against the end wall 4. At the end ofthe elongate member 2 remote from the end wall 4, the member carries an elongate cutter 28 which is resiliently mounted on the member by means of a leaf spring 29.The elongate cutter 28 has a rectilinear cutting edge 30 which is parallel to the axis ofthe centres of curvature of the curved smooth surface 14 of the table 12 and which is normal to the pivotal axis 5 of the elongate member 2. Secured to the elongate member 2 near its free end remote from the end wall 4 by means of a screw 32 is a button 31 which protru des through an aperture 33 in the outer elongate member 3. The elongate member2 is urged away from the fixed elongate member 1 by a coil spring 37 bounding an adjustable screw 36 which upstands from the elongate member 1 and whose head protru des into a hold 38 in the elongate member 2.For adju sting, within a limited range, the depth of thereby ctilinear scorewhich the rectilinear cutting edge 30 of the cutter 28 will effect across each optical fibre of an optical fibre ribbon, an adjustable screw 34 is carried by the elongate member 1 and constitutes an abut mentagainstwhichthescrew32will abutwhenthe elongate member is caused to pivot about the axis 5 against the action of the coil spring 37 by depression of the button 31.

When the hand tool isto be employed to effect a rectilinear score across each optical fibre of an opti cal fibre ribbon of the kind described, any plastics covering on the fibres over a part of their lengths adjacenttheirfree ends is removed and the optical fibre ribbon is positioned on the upperflat surface 7 of the arm 6 against one of the risers 19 constituting the guide means so that the stripped optical fibres lie side-by-side across the convexly curved upper surface 14 of the table 12. The lever mechanism 10 ofthe clamping means 9 adjacent the riser 19 is then snapped into the clamping position to clamp the optical fibre ribbon to the surface 7 of the arm 6 by the resilient pad 11.The button 31 is then depressed against the action of the spring 37 to cause the elongate arm 2 to pivot about its pivotal axis 5 with respect to the rigid elongate arm 1 so that there- ctilinear cutting edge 30 of the elongate cutter 28 effects a rectilinear score across each optical fibre of the optical fibre ribbon. The pressure on the button 31 is then isthen released andthe elongatearm 2 returnsto its normal position under the action of the spring 37.

Manual pressure isthen applied to the under- surface 40 of the table 12, which is exposed in the opening ofthe chamber 15 in the undersurface 17 of the laterally extending arm 6,to causethetableto move towards the clamping means 9 to bend the transversely scored optical fibres ofthe optical fibre ribbon about an axis normal to the axes of the optical fibres to causethem to cleave so that the optical fibres ofthe ribbon have end faces which are flat and lie in a common plane radial to the axes ofthe optical fibres.

Claims (12)

1. A manual device for bending an optical fibre ribbon of the kind described about an axis extending substantially normal to the axes ofthe optical fibres, which manual device comprises a table which has a substantially smooth surface of convexly curved form and, on each of two opposite sides of the axis containing the centres of curvature of the convexly curved surface ofthetable, one of a pairofclamping and guide meansforclamping and guiding across the table an optical fibre ribbon of the kind described, which has in each of its optical fibres a transverse score which is substantially normal to the axes ofthe optical fibre the transverse scores in the optical fibres lying in a substantially common plane, in such away thatthetransverse scores overlie and are remote from the convexly curved surface of the table and the optical fibres ofthe ribbon lie substantially normal to the axis containing the centres of curvature ofthe convexly curved surface of the table, the table and the pairs of clamping and guide means being interconnected in such awaythatthetable, orthe pairs of clamping and guide means, is or are constrained to move towards or away from the pairs of clamping and guide means, orthetable, in a direction substantially normal to the optical fibres ofthe ribbon and to said axis containing the centres of curvature ofthe convexly curved surface of the table and is orare urged awayfrom the pair of clamping and guide means, or the table, by associated spring means, the arrangement being such that, after an optical fibre ribbon has been so clamped and guided by said clamping and guide means, relative movement can be effected between the table and the pairs of clamping and guide means against the action of said associated spring means to cause the convexly curved surface of the table to engage and bend the optical fibre ribbon about an axis extending substantially normal to the axes ofthe optical fibres to such an extentthatthefibresoftheribbon cleave to form on the fibres end faces which are substantially flat and lie in a common plane radial to the axes ofthe fibres.

2. A manual device as claimed in Claim 1, wherein at least one surface ofthe clamping means which will be contiguous with an optical fibre ribbon, and the convexly curved smooth surface of the table, are made of a material which is sufficiently resilient, or which is rendered sufficiently resilient, to ac commodate the shock of any optical fibre breaking and thereby limitthe extent to which such a shock will be imparted to a neighbouring optical fibre.

3. A manual device as claimed in Claim 2, wherein at least one surface of the clamping means which will be contiguous with an optical fibre ribbon, and the convexly curved smooth surface ofthe table, are made of a rubber-like material of about 60 shore hardness.

4. A manual device as claimed in any one ofthe preceding Claims, wherein each pair of clamping and guide means is mounted on a substantially rigid base and the table is slidably mounted in a chamber between the pairs of clamping and guide means and is urged away from the pairs of clamping and guide means by an associated spring.

5. A manual device as claimed in any one of Claims 1 to 3, wherein thetable is mounted on a sub stantiallyrigid elongate base and each pairofclam- ping and guide means is slidably mounted on a shaft upstanding from the base on one side ofthetable and is urged away from the base by a coil spring positioned on the shaft.

6. A manual device as claimed in Claim 4, wherein each ofthe clamping means comprises a bed having a substantially smooth flat surface and, for clamping an optical fibre ribbon on the bed, a pivotally mounted lever mechanism which can be snapped into the closed or clamping position and which has a clamping pad of substantially resilient material.

7. A manual device as claimed in Claim 6, wherein the beds ofthe clamping means are integral parts of an arm which extends laterally across the table in a direction substantially normal to the axis of the centres of curvature of the convexly curved sur face,the chamberin which thetable isslidably mounted opening into the surface of the arm between the clamping means.

8. A manual device as claimed in Claim 7, wherein the chamber extends through and opens into the opposite surface of the arm so that the table can be moved towards the clamping and guide means against the action of said associated spring by manual pressure.

9. A manual device as claimed in Claim 7, wherein the undersurface of the table in the chamber is engaged by a cam controlled by an operating lever pivotably mounted on a side wall ofthe arm.

10. Amanual device as claimed in any one of Claims 6 to 9, wherein the guide means on each of said two opposite sides of the table comprises the riser of a step on the bed ofthe clamping means, which step extends substantially normal to the axis of the centres of curvature of the convexly curved smooth surface ofthetable.

11. A manual device for bending an optical fibre ribbon of the kind described about an axis extending substantially normal to the axes of the optical fibres, which manual device is substantially as hereinbefore described with reference to and as shown in the accompanying drawings.

12. In a hand tool for effecting a transverse score in each optical fibre of an optical fibre ribbon ofthe kind described, which hand tool comprises at least two elongate members pivotally connected together at or near one of their ends about an axis extending transverse to the members, one of the members or at least one ofthe members being urged away from the other member or members by associated spring means, a manual device as claimed in any one ofthe preceding Claims mounted on one of said members at a position remote from said pivotal axis, and an elongate cutterwhich is associated with the table of said manual device and is mounted on the other or another of the members and which has a rectilinear cutting edgewhich extends substantially parallel to the axis containing the centres of curvature ofthe convexly curved smooth surface ofthetable.