Signal transmitting cable
A cable ( 302 ) has (8) fibers ( 304 ) are encapsulated by a UV curable layer ( 306 ) having a diameter of approximately (1010) microns, and (16) outer fibers ( 316 ) arranged in a circular formation around the inner fibers ( 304 ). The optical fibers ( 304 ) are held in position by means of the UV curable layer ( 306 ) so that the UV curable material of the layer ( 306 ) does not penetrate into the gaps between the optical fibers ( 304 ) and the outermost optical fibers ( 304 ) are restrained by the layer from moving axially. It is found that such an arrangement provides surprisingly favorable bending properties, making the cable particularly suitable for installation in a tube by means of blowing.
1. A signal transmitting cable for installation into a tube by means of blowing by compressed fluid, the cable comprising a first signal transmitting portion including a plurality of elongate, flexible first optical signal transmitting members, wherein the first optical signal transmitting members of the first signal transmitting portion are surrounded by a first layer of resin material curable by means of radiation such that only the outermost optical signal transmitting members are in contact with said first layer, and said first optical signal transmitting members are arranged to form at least three rows, wherein for each said row containing a plurality of said members, said members are arranged such that neighbouring members of said row are in touching contact with each other, each recess formed by neighbouring members of a first said row facing towards a second said row accommodates a respective member of said second row, said first layer is in touching contact with substantially all of the outward facing surface of the first signal transmitting portion, and wherein a material forming an outer surface of the cable is modified to facilitate installation into a duct by means of fluid flow.
2. A cable according to claim 1 , wherein the first signal transmitting portion includes 12 said first optical signal transmitting members arranged in 4 rows having 2, 3, 4 and 3 optical signal transmitting members respectively.
3. A cable according to claim 1 , wherein the first signal transmitting portion includes 18 said first optical signal transmitting members arranged in 5 rows having 2, 4, 5, 4 and 3 optical signal transmitting members respectively.
4. A cable according to claim 1 , wherein the first signal transmitting portion includes 24 said first optical signal transmitting members arranged in 5 rows having 4, 5, 6, 5 and 4 optical signal transmitting members respectively.
5. A cable according to claim 1 , wherein said first layer is formed of resin material cured by means of ultraviolet radiation.
6. A cable according to claim 1 , further comprising a second signal transmitting portion comprising a plurality of elongate, flexible second optical signal transmitting members arranged around the periphery of said first layer, wherein said external dimensions of said first layer are arranged such that each said second optical signal transmitting member is in touching contact with two adjacent said second optical signal transmitting members.
7. A cable according to claim 6 , further comprising a third signal transmitting portion comprising a plurality of elongate, flexible third optical signal transmitting members arranged outwardly of said second signal transmitting portion.
8. A cable according to claim 6 , wherein said second optical signal transmitting members are embedded in a second layer.
9. A cable according to claim 1 , wherein said outer surface is provided with ribs.
10. A cable according to claim 1 , wherein said outer surface includes at least one anti-static material.
11. A cable according to claim 1 , wherein said outer surface includes at least one friction reducing material.
12. A cable according to claim 1 , further comprising an outermost layer having an inner periphery longer than the outer periphery of the layer adjacent thereto to enable removal of said outermost layer from the cable.
13. A method of forming a signal transmitting cable, the method comprising:
arranging a plurality of elongate, flexible first optical signal transmitting members in at least three rows, wherein for each said row containing a plurality of said members, said members are arranged such that neighbouring members of a row are in touching contact with each other, and each recess formed by neighbouring members of a first said row facing towards a second said row accommodates a respective member of a said second row;
surrounding said first optical signal transmitting members by a first layer of resin material curable by means of radiation such that only the outermost optical signal transmitting layers are in contact with said first layer, and said first layer is in touching contact with substantially all of the outward facing surface of the first signal transmitting portion;
curing said first layer by means of radiation; and
modifying a material forming an outer surface of the cable to facilitate installation into a duct by means of fluid flow.
14. A method according to claim 13 , further comprising:
arranging a plurality of elongate, flexible second optical signal transmitting members around the periphery of said first layer such that each said second signal transmitting member is in touching contact with two adjacent said second optical signal transmitting members; and
fixing said second optical signal transmitting members in position relative to said first layer.
15. A method according to claim 14 , wherein the step of fixing said second optical signal transmitting members in position relative to said first layer comprises embedding said second optical signal transmitting members in a second layer.