USB cable and method for producing the same
View Patent ↗A method and apparatus for producing a USB cable capable of being fed out of and returned to a cable reel is disclosed along with a cable reel that houses the cable and provides connectivity for the cable.
1. A universal serial bus cord reel apparatus comprising:
a cable, the cable comprising a) first and second data wires adjacent to each other, and twisted around each other at approximately four twists per inch; b) a first braided shield surrounding the first and second data wires to prevent electromagnetic or radio frequency interference; c) two or more additional conductors adjacent to the shield surrounding the first and second data wires, the additional wires being twisted about the shield at approximately two twists per inch; d) a polytetrafluoroethylene cover enclosing the additional conductors and first and second data wires; and e) a second shield enclosing the polytetrafluoroethylene cover; whereby the cable has an impedance of approximately 90 ohms;
a universal serial bus connector at each end of the cable;
a housing;
a reel attached to and rotatable with respect to the housing for accepting the cable;
a spring mounted between the housing and the reel for biasing the rotation of the reel in one direction for retracting the cable;
a ratchet attached to the housing for selectively restraining rotation of the reel whereby the cable may be maintained in an extended position, or retracted and wound on the reel.
2. A method for manufacturing a universal serial bus cable comprising the steps of:
placing first and second data wires adjacent to each other;
twisting the first and second data wires about each other at approximately four twists per inch;
covering the twisted first and second data wires with a braided shield;
placing one or more additional data wires in close proximity to the shield;
forming a circular cross-section of the first and second data wires, the braided shield, and the one or more additional data wires by either twisting or helically fluting the one or more additional data wires about the braided shield at approximately two twists per inch, so that the resulting structure has a bend radius of at least approximately 55 millimeters;
coating the braided shield and one or more additional data wires with a low-friction substance;
covering the low-friction substance with a second shield resisting radio-frequency and electromagnetic interference, so that the resulting structure has an impedance of approximately 90 ohms and a signal rate of at least approximately 1.5 megabytes per second.