Electricity: conductors and insulators – Conduits – cables or conductors – Insulated
Reexamination Certificate
2001-07-27
2002-12-17
Nguyen, Chau N. (Department: 2831)
Electricity: conductors and insulators
Conduits, cables or conductors
Insulated
Reexamination Certificate
active
06495763
ABSTRACT:
This invention relates to an improvement in the handling of reactance, improved electron flow balance, enhanced electron movement and subsequent improved performance in a signal carrying cable design to be used, for example, as an interconnect cable with phono or RCA type plug termination (connecting two pieces of electronic equipment such as CD or DVD player to pre-amplifier, pre-amplifier to amplifier etc) and loudspeaker cable (connecting amplifier to loudspeaker) for audio and home theatre applications. The invention is also effective for other cable applications such as data communication cables, microphone leads, patch cords and the like, video and digital cables, and any other signal carrying cables. Furthermore the invention can be used effectively for copper traces for circuit boards and in some signal carrying connecting hardware such as RCA type phono plugs and sockets, RF or coaxial connectors, and spade connectors wherever a signal and return conductor are involved.
As such, this invention has particular but not exclusive application to signal carrying cables, and for illustrative purpose reference will be made to such application.
Many signal carrying cable products are expensive, complex designs that are difficult to manufacture.
The complexity of the cable designs come about as designers seek to electrically optimize cables by reducing distortion and coloration to a minimal level. Two types of distortion that are recognized as being problematic are inductive reactance and capacitive reactance.
Variable current flow in a conductor generates inductance and capacitance as well as inductive reactance and capacitive reactance. Inductive reactance is directly proportional to frequency. So, when frequency increases, inductive reactance also increases. Capacitive reactance is inversely proportional to frequency. In other words, as frequency increases, capacitive reactance decreases.
In a signal carrying cable where the signal and return have the same strand number, strand size and mass, the overall inductive and capacitive reactance characteristics are increased (i.e. a doubling effect where reactance in the signal is combined with the reactance in the return) and as such the reactive resistance to each frequency is not balanced.
The present invention overcomes problems of reactance in signal carrying cables by speeding up the flow of electrons in the return conductor and balancing the reactive characteristics between signal and return. This is achieved by increasing the mass in the return conductor in relation to the mass of the signal conductor by using a specific ratio. When the mass of the return conductor is greater than the mass in the signal conductor the resistance of the return is significantly lower (than that of the signal) thereby providing a faster pathway for electrons to travel.
The return conductor is by its nature always responding to the signal conductor because it is constantly in delay mode. In the present invention the increased size and mass of the return conductor enables the return to respond more rapidly to the signal allowing an unimpeded and speedy flow of electrons.
By enhancing the flow of electrons in the cable, problems such as capacitive and inductive reactance appear to be diminished. A useful analogy is wind effect on a speeding bullet. The faster the bullet, the less influence wind has on its movement.
When using the ratio, the electron flow between signal and return conductors also appears more evenly balanced, with electrons at all frequencies travelling at the same apparent speed.
The ratio at the heart of the present invention is a ratio of firstly the cross sectional area of the signal core in relation to the return core, and secondly the diameter or perimeter of each electrically conductive strand in the signal in relation to the return, where the mass is intentionally increased in the return core.
The present invention relates to a cable with cores defined as the following:
1: A single strand within an insulated jacket hereinafter called “solid core”.
2: A multi-strand core comprising non-insulated strands grouped together within an insulated jacket hereinafter called “multi-strand core”.
3: Multiple strands individually insulated which may be grouped together within an insulated jacket hereinafter called “Litz style core”.
4: Any of the above where the signal conductor core is shielded by a braided or foil shield as in a coaxial configuration, hereinafter called “shielded core”.
The ratio of cross sectional area of the total signal core in relation to the total return core for solid cores, multi-strand cores and Litz-style cores is between 1:2.6 and 1:4.0 with the preferred ratio being 1:2.778.
When using a shielded core, the preferred ratio of cross sectional area of the total signal core in relation to the total return core is 1:3.56.
The increase in preferred ratio used for a shielded core (for example coaxial style 75 Ohm or 110 Ohm video or digital cable) appears to be due to a capacitive and/or inductive effect caused by an interaction between signal conductor and the surrounding shield, and return conductor and the shield.
The preferred ratio may also increase or decrease as a result of various shielding configurations, insulation types and metal conductors that may be used or the combination thereof. For example heavier shielding and/or change of impedance between signal conductor and shield may change the ratio. Similarly the use of high purity silver conductors may require a slightly different ratio to Oxygen free copper (OFC) conductors.
The ratio of stranding size of individual solid strand/s within the signal core in relation to individual solid strand/s within the return core of solid cores, multi-strand cores and Litz-style cores, and based on the diameter or perimeter of each strand, is 1:1.6 to 1:2.0, with the preferred ratio being 1:1.667. When using a shielded core, the preferred ratio is 1:1.887.
The preferred signal carrying cable design is one that uses the cross sectional area ratio and the diameter or perimeter ratio together.
For cables comprising multi-strand cores or Litz style cores and where the diameter or perimeter of each individual strand is the same for both signal and return, the ratio is based on the cross sectional area between the signal and return core and is between 1:2.6 to 1:4.0 with the preferred ratio being 1:2.778. When using a shielded core, the preferred ratio is 1:3.56.
Using the ratio with multi-strand cores or Litz style cores, the signal transmission appears to improve when the least number of strands are used. From our understanding of reactance this makes sense: less strands means that less reactance distortion effects are generated. Further, when using multi-strand cables, small diode or rectification effects arise from imperfect contact among the strands. Again, fewer strands are better.
Signal carrying cables can comprise conductor strands other than round i.e. square, flat, rectangular, tubular etc
There are currently five types of geometry's utilized in signal carrying cables, the coaxial, the twisted pair, the woven, the helical pair and the parallel pair.
The present invention is preferably utilized in a parallel configuration where each conductive core needs to be laid beside each other and not twisted together.
Twisting of cores increases inductive and capacitive reactance in cables. However, where specific impedance is required i.e. 75 Ohm or 110 Ohm for digital and video use, then cores may be twisted to achieve the desired impedance.
To date, there has not been a signal carrying cable design that addresses and minimizes the effects of the above mentioned reactance problems by using a specific ratio as per the present invention. There is therefore a need for this invention.
REFERENCES:
patent: 4628151 (1986-12-01), Cardas
patent: 5428189 (1995-06-01), Dorner et al.
patent: 6194663 (2001-02-01), Friesen et al.
Eichmann Keith Louis
Woodland Robert Bruce
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