Fiber multitube optical fiber cable

• US 10,641,981 B1
• Filed: 12/18/2018
• Issued: 05/05/2020
• Est. Priority Date: 12/18/2018
• Status: Active Grant

• Current Assignee: Sterlite Technologies Limited (Volcan Investments Ltd.)
• Original Assignee: Sterlite Technologies Limited (Volcan Investments Ltd.)
• Inventors: Sahoo, Kishore, Kumar, Sravan, Chintada, Kavya, Shukla, Vikash, Murthy, Venkatesh, Mishra, Atul
• Primary Examiner(s): Blevins, Jerry M
• Application Number:
  US16/224,505
• Time in Patent Office: 504 Days
• Field of Search: 385111
• CPC Class Codes: G02B 6/4413 Helical structure
• CPC Class Codes: G02B 6/4431 with provision in the protective covering, e.g. weak line, for gaining access to one or more fibres, e.g. for branching or tapping break-out terminations G02B6/4471
• CPC Class Codes: G02B 6/4434 Central member to take up tensile loads
• CPC Class Codes: G02B 6/44384 the means comprising water blocking or hydrophobic materials G02B6/4439, G02B6/4479 take precedence

Abstract

The present disclosure provides an optical fiber cable. The optical fiber cable includes a central strength member. The central strength member lies substantially along a longitudinal axis of the optical fiber cable. The optical fiber cable includes at least one buffer tube. The at least one buffer tube is stranded helically around the central strength member. Each of the at least one buffer tube encapsulates at least one optical fiber. The optical fiber cable includes a first layer. The first layer circumferentially surrounds a core of the optical fiber cable. The optical fiber cable includes a second layer. The second layer is formed of high density polyethylene. The optical fiber cable includes at least one set of water swellable yarn and a plurality of ripcords.

Claims

1. An optical fiber cable, comprising:

a central strength member lying substantially along a longitudinal axis of the optical fiber cable, wherein the central strength member being characterized by a first diameter, wherein the first diameter of the central strength member is 3.2 millimeter;

at least one buffer tube, wherein the at least one buffer tube being stranded helically around the central strength member, wherein each of the at least one buffer tube encapsulates optical fiber, wherein a change in attenuation of each of the at least one optical fiber is 0.05 decibels per kilometer at a wavelength of 1550 nanometer, wherein the at least one buffer tube being formed of polybutylene terephthalate, wherein the at least one buffer tube being maintained in tension during stranding, wherein the tension maintained during stranding is 900 to 1000 grams, wherein the at least one buffer tube being stranded around the central strength member by maintaining a negative excess elongation of 0.01%, wherein each of the at least one buffer tube being characterized by;

an inner diameter, wherein the inner diameter of each of the at least one buffer tube is in a range of 1.6±

0.05 millimeters,

an outer diameter, wherein the outer diameter of each of the at least one buffer tube is in a range of about 2.0±

0.05 millimeters,

a first thickness, wherein the first thickness of each of the at least one buffer tube is in a range of 200 microns±

50 microns,

a first density, wherein the first density of each of the at least one buffer tube is 1.31 gram per cubic centimeter,

a first layer, wherein the first layer circumferentially surrounds the at least one buffer tube, wherein the first layer is formed of a pair of binder yarns, wherein the pair of binder yarn comprising;

a first binder yarn, wherein the first binder yarn being wrapped helically in clockwise direction;

a second binder yarn, wherein the second binder yarn being wrapped helically in anti-clockwise direction;

a plurality of sets of water swellable yarn; and

a second layer, wherein the second layer is a covering jacket of the optical fiber cable, wherein the second layer circumferentially surrounds the first layer, wherein the second layer being formed of high density polyethylene, wherein the second layer being characterized by a second thickness, wherein the second thickness of the second layer lies in a range of 0.4 millimeter to 0.6 millimeter, and

wherein the optical fiber cable being characterized by a fourth diameter, wherein the fourth diameter is radial distance between diametrically opposite ends of the optical fiber cable, wherein the fourth diameter of the optical fiber cable is in a range of 8.0±

0.3 millimeters.

2. The optical fiber cable as recited in claim 1, wherein the at least one buffer tube in the optical fiber cable is 8.

3. The optical fiber cable as recited in claim 1, wherein the central strength member includes a polyethylene coating.

4. The optical fiber cable as recited in claim 1, wherein the plurality of sets of water swellable yarn includes a first set of plurality of water swellable yarns, wherein the first set of plurality of water swellable yarns being helically wrapped around the central strength member.

5. The optical fiber cable as recited in claim 4, wherein the plurality of sets of water swellable yarns includes a second set of plurality of water swellable yarns, wherein the second set of plurality of water swellable yarns being helically wrapped around a core of the optical fiber cable.

6. The optical fiber cable as recited in claim 1, wherein each of the at least one buffer tube has a lay length in the range of 95 millimeter to 100 millimeter.

7. The optical fiber cable as recited in claim 1, wherein the second layer being characterized by a second density, wherein the second density of the second layer being in a range of 0.90 gram per cubic centimeter to 0.96 gram per cubic centimeter.

8. The optical fiber cable as recited in claim 1, wherein the optical fiber cable has a coverage factor of 99%.

9. The optical fiber cable as recited in claim 1, wherein the optical fiber cable has a buffer tube packing factor of 58% to 66%.

10. The optical fiber cable as recited in claim 1, wherein each of the at least one optical fiber has a diameter of 200 microns.

11. The optical fiber cable as recited in claim 1, wherein the optical fiber cable includes a plurality of ripcords, wherein a color of the plurality of ripcords is different from a color of the first layer, and wherein the color of the plurality of ripcords is different from a color of the at least one set of water swellable yarn.

12. The optical fiber cable as recited in claim 1, wherein the optical fiber cable is blown into a duct having an inner diameter of about 10 millimeter and an outer diameter of 14 millimeter.

13. The optical fiber cable as recited in claim 1, wherein a number of the at least one optical fiber in each of the at least one buffer tube is 36.

14. The optical fiber cable as recited in claim 1, wherein the optical fiber cable has 288 optical fibers.

15. The optical fiber cable as recited in claim 1, wherein the maximum core concentricity error of each of the at least one optical fiber is 0.5 microns.

16. The optical fiber cable as recited in claim 1, wherein the at least one optical fiber has primary protective composite coating consisting of a double layer of acrylate.

17. The optical fiber cable as recited in claim 1, wherein the central strength member is formed of fiber reinforced plastic.

18. The optical fiber cable as recited in claim 1, wherein the optical fiber cable is characterized by a cable weight, wherein the cable weight of the optical fiber cable is in a range of 58 kilogram per kilometer to 70 kilogram per kilometer.