Textiles: spinning – twisting – and twining – Apparatus and processes – Alternate twist
Reexamination Certificate
1999-03-18
2001-11-13
Worrell, Danny (Department: 3741)
Textiles: spinning, twisting, and twining
Apparatus and processes
Alternate twist
C057S031000, C385S147000
Reexamination Certificate
active
06314713
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to method and system for identifying a feature on a generally longitudinal member which is advanced longitudinally and then marking the advancing member based on the identification, and more particularly, for identifying S-Z reversals on an optical fiber cable including a strand of S-Z stranded buffer tubes during advance of the optical fiber cable on a cable manufacturing line and for marking either the strand or covering applied to the strand during manufacture of the cable, based on the identified reversals.
BACKGROUND
Optical fiber cables are currently used in telecommunication applications for transmitting optical signals from one location to another. Oftentimes, it is desired to tap or splice into an optical fiber cable at a point other than at an end of an optical fiber cable to obtain access to an optical fiber in the cable.
A large number of optical fiber cables currently in use and being manufactured have a core formed from buffer tubes, each of which encloses a plurality of optical fibers. The buffer tubes typically are stranded longitudinally along the length of a central strength member using the well known technique of S-Z or alternate-hand stranding. Although the core without a jacket can be used as a cable, the core usually is enclosed by a plastic jacketing or sheath which obscures the positions on the strand where the S-Z reversals occur. At the S-Z reversal positions of the S-Z strand, the buffer tube lengths are longer than the length of the overlying elements of the cable, e.g., the jacket, which makes slack available in the tubes and the fibers contained in the tubes. As is known, this slack eases the process of making connections to the fibers in the cable at the point where the cable is entered.
It is known that markings applied on the outer jacket of an optical fiber cable, which includes S-Z stranded buffer tubes, at positions corresponding to the S-Z reversals in the strand are advantageous because the markings identify on the outside of the cable the positions of the S-Z reversals within the cable. See, for example, U.S. Pat. Nos. 4,828,352, 4,746,190 and 4,496,214, incorporated by reference herein. These markings, in effect, identify the slack points or S-Z reversal positions and guide one desiring access to a fiber in the cable to a point along the cable where access is more easily obtainable.
The current art, however, does not describe how to identify accurately the position of an S-Z reversal in a strand of S-Z stranded buffer tubes during optical fiber cable manufacture and, accordingly, how to place a mark accurately on jacketing applied on the strand of the cable at a position corresponding to an S-Z reversal of the strand contained within the cable, based on the identification of the S-Z reversals and as part of an integral and efficient cable manufacturing process performed along a conventional cabling line.
Therefore, there exists a need for a method and system for identifying the location of an S-Z reversal feature on a strand of S-Z stranded buffer tubes included in an optical fiber cable while the cable is advanced longitudinally along an optical fiber cable manufacturing line and for marking a covering, such as a jacket, applied to the strand at a position corresponding to the identified S-Z reversal, based on the identification of the S-Z reversal on the advancing cable.
SUMMARY OF THE INVENTION
In accordance with the present invention, a generally longitudinal member is advanced longitudinally on a path extending from a first position to a second position and a feature on the member is detected at a selected position on the path which is not the same as the second position. Based on the detection of the feature on the member and by monitoring the advance of the member on the path between the first position and the second position, indicia can be applied to a desired position on the member at a position on the path spaced from the selected position in the direction of the advance of the member.
In one aspect of the invention, the feature is created on the member while the member is advancing on the path and before the member reaches the second position. The feature and its position on the member is detected by monitoring the advance of the member between the first and second positions and based on knowledge of the location on the path where the feature is created on the member.
In a preferred embodiment, the member is an optical fiber cable including a strand of buffer tubes, each of which contains at least one optical fiber. The tubes are S-Z stranded together and around a central strength member by a stranding means at the first position. The feature to be identified is an S-Z reversal of the buffer tubes in the strand. A marker for applying indicia to the strand, or a covering encircling the strand, is at the second position. A means for monitoring advance of the cable is coupled to the path and monitors the advance of the cable from the stranding means to the marker. A microcontroller, which is coupled to the stranding means, the marker and the monitoring means, correlates the position on the strand where an S-Z reversal is created with the advance of the cable from the stranding means to the marker. The microcontroller transmits a trigger signal to the marker to cause the marker to apply indicia on the strand, or if present, a covering encircling the strand, at the position on the cable detected as having an S-Z reversal when the cable passes opposite the marker.
In another aspect of the invention, the feature is already present on the member before the member is advanced on the path and an optical light detector is utilized to detect the feature. The feature and its position on the member is detected by monitoring the advance of the member between the first and second positions and based on a knowledge of the location on the path where the feature on the advancing member is detected.
In an alternative preferred embodiment, the member is an optical fiber cable including a strand of S-Z stranded buffer tubes, each of which contains at least one optical fiber, and the feature is an S-Z reversal on the strand. An optical reflected light detector is at the first position and the marker is at the second position. A means for monitoring advance of the cable is coupled to the path and monitors advance of the cable on the path from the detector to the marker. A microcontroller is coupled to the optical reflected light detector, the marker and the monitoring means. The detector obtains optical image samples of the strand which are then converted into representative digital intensity data values. The microcontroller processes the intensity data to identify an image sample of the strand that includes an S-Z reversal and tracks the position of the identified S-Z reversal on the advancing cable based on data provided by the monitoring means. Further, the microcontroller transmits a trigger signal to the marker to cause the marker to apply indicia to a desired position on a jacketing layer which is applied to the strand as the cable advances from the detector to the marker. Preferably, the desired position on the jacketing layer corresponds to the position of an S-Z reversal of the underlying strand which the jacketing layer covers.
In one of the preferred embodiments, the optical reflected light detector includes a linear sensor which generates digital intensity data representative of linear optical image samples obtained of the strand. The microcontroller performs processing operations on the intensity data to identify S-Z reversals in the sampled images of the strand by first accounting for any shifting of the strand relative to the line of sensors between an image sample and the next consecutive image sample and then determining the apparent motion of the strand between the consecutive image samples. The microcontroller, based on the apparent motion determination for image samples consecutively preceding and succeeding a subject image sample, identifies whether the subject image sample
Fitz Jonathan G.
McNeill Stephen Richard
Norris McLaughlin & Marcus P.A.
Pirelli Cables & Systems, LLC
Worrell Danny
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