Electricity: conductors and insulators – Conduits – cables or conductors – Insulated
Reexamination Certificate
1999-07-21
2001-04-10
Kincaid, Kristine (Department: 2831)
Electricity: conductors and insulators
Conduits, cables or conductors
Insulated
C174S1170FF, C174S027000
Reexamination Certificate
active
06215071
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a flat cable, and more particularly to a flat cable comprising fused portions and twisted pair portions and a process for producing the same.
BACKGROUND OF THE INVENTION
In commercially available flat cables comprising fused portions and twisted pair portions, the fused portions to be connected to a connector are disposed at equal spacings with each of the fused portions being sandwiched between the twisted pair portions.
In the twisted pair portions in this type of flat cables, adjacent twisted pairs are twisted in directions opposite to each other from the viewpoint of preventing crosstalk. When attention is drawn to one twisted pair, however, in some of this type of flat cables, the twisted pair portions sandwiching the fused portion are twisted in directions opposite to each other, while in the other flat cables of this type, the twisted pair portions sandwiching the fused portion are always twisted in the same direction. This difference is attributable to a difference in the production system.
An example of the construction of the system for producing flat cables will be explained.
A system for producing a flat cable comprises: a feeder for delivering insulated conductors for a flat cable at even tension; a twister for twisting two insulated conductors to each other to form a twisted pair; a fusing device for fusing all the insulated conductors to one another to form a fused portion with the insulated conductors being juxtaposed to each other; a take-up unit for taking up at a constant speed insulated conductors that have been subjected to pair twisting and fusing; a coiler for winding the cable around a bobbin; a controller for controlling the operation and stopping of the twister and for controlling the operation and stopping of the fusing device; and the like.
In the flat cable wherein the twisted pair portions sandwiching the fused portion are twisted in directions opposite to each other, during the formation of a certain twisted pair portion, twist is accumulated in the insulated conductors between the twister and the feeder. Since, however, twisting is carried out in the opposite direction in the formation of the next twisted pair portion, the accumulation of the twist is eliminated. On the other hand, in the flat cable wherein the twisted pair portions sandwiching the fused portion are always twisted in the same direction, the twist between the twister and the feeder is increasingly accumulated. The twist cannot be infinitely accumulated in the insulated conductors between the twister and the feeder. Therefore, a twist back mechanism for eliminating the twist should be provided at the delivery portion.
The twist back mechanism should be provided in number equal to the number of pairs. In some of actual flat cables, the number of pairs is 50 or 100. This incurs very high cost for the provision of the twist back mechanisms.
The conventional flat cables described above are produced on the premise that the mounting spacings of the connector are constant. In recent years, however, there is a demand that the connector is provided at different mounting spacings in one cable, for example, at mounting spacings of 125 mm, 250 mm, 325 mm and the like. In order to meet the above demand, when a cable with the fused portions being provided at spacings of 125 mm and 250 mm is taken by way of example, if the length of the fused portions is 50 mm with the pitch of the twisted pairs being 25 mm, the number of twists is 3 in the portion having a fused portion spacing of 125 mm and 8 in the portion having a fused portion spacing of 250 mm. In the production of a cable wherein the portion with the number of twists being 3 is provided alternately with the portion with the number of twists being 8, when the twist sense is changed for the formation of each of the fused portions as described above, twist is increasingly accumulated between the feeder and the twister. This ultimately requires the provision of twist back mechanisms.
SUMMARY OF THE INVENTION
The present inventors have found that the accumulation of the twist can be minimized by independently regulating the twist sense of the twisted pair portions.
Accordingly, it is an object of the invention to provide a flat cable with the spacings of fused portions being not constant that can be produced without any twist back mechanism, and to provide a process for producing the same.
Thus, according to the first feature of the invention, a flat cable comprises fused portions and twisted pair portions, the length of the twisted pair portions being not constant, the twist pitch of the twisted pair portions being substantially constant independently of the length of the twisted pair portions, some of the twisted pair portions being constituted by S twisted pair portions with the other twisted pair portions being constituted by Z twisted pair portions, twisting in the twisted pair portions having been carried out in such a manner that, when the number of twists in the S twisted pair portions in the longitudinal direction of the flat cable is added as “plus (+)” value with the number of twists in the Z twisted pair portions being added as “minus (−)” value, the twist sense in the next twisted pair portion is Z twist sense if the integrated value of the number of twists is plus (+) while the twist sense in the next twisted pair portion is S twist sense if the integrated value of the number of twists is minus (−).
The determination of the twist sense in the twisted pair portions by the above method permits the twist accumulated in insulated conductors between the feeder and the twister to be suppressed to a given extent or less. This in turn eliminates the need to provide any twist back mechanism in the delivery portion even when various fused portion spacings are provided, contributing to reduced production system cost. Further, also for the controller regarding pair twisting, the twist sense of the twisted pair portion is determined based on the integrated value obtained by adding up or subtracting the number of twists according to the twist sense. This eliminates the need to consider the number of twists in the next twisting or to previously determine the twist sense and hence can save a lot of time and labor.
According to the second feature of the invention, there is provided a process for producing a flat cable comprising fused portions and twisted pair portions, the length of the twisted pair portions being not constant, the twist pitch of the twisted pair portions being substantially constant independently of the length of the twisted pair portions, wherein twisting of the twisted pair portions is carried out in S twist sense or Z twist sense based on the integrated value of twists in the twisted portions determined in such a manner that when twisting in the twisted pair portion is carried out in the S twist sense, the number of twists is added to the integrated value while when twisting in the twisted pair portion is carried out in the Z twist sense, the number of twists in the twisted pair portion is subtracted from the integrated value and wherein, in initiating the S twisting of the twisted pair portions, when the integrated value of twists in the twisted pair portions is plus (+), twisting is carried out in the Z twist sense while when the integrated value of twists in the twisted pair portions is minus (−), twisting is carried out in the S twist sense.
REFERENCES:
patent: 4404424 (1983-09-01), King et al.
patent: 4413469 (1983-11-01), Paquin
patent: 4767891 (1988-08-01), Biegon et al.
patent: 4837405 (1989-06-01), Bonjour et al.
patent: 4992625 (1991-02-01), Izui et al.
patent: 5142105 (1992-08-01), Kihlken et al.
Aoyagi Masaaki
Kasahara Tsukasa
Mizushima Satoshi
Mochizuki Osamu
Hitachi Cable Ltd.
Kincaid Kristine
Mayo III William H.
Scully Scott Murphy & Presser
LandOfFree
Flat cable and process for producing the same does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Flat cable and process for producing the same, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Flat cable and process for producing the same will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2525955