Cable for Conducting Simultaneously Electricity and Light

The invention concerns a cable with at least one core and at least one layer of insulation

Electric cable is employed is almost every field of technology. Antenna signals for example are forwarded to receivers, television or radio receivers for example, by way of coaxial cable. Telephone communications are no longer conceivable without coaxial cable. In this area in particular, however, coaxial cable is being increasingly replaced with optical cable, which features an essentially more extensive band width and lower attenuation, because light is a form of energy that requires no shielding, and because the crosstalk that is so irritating with coaxial cable does not occur at all with optical.

Many types of equipment, television sets and video recorders for example, are designed only for coaxial cable. The video signal is transmitted from the recorder to the television set over a coaxial cable. To operate a combination television set and video recorder, however, it is of advantage to transmit control signals in addition to video and audio signals between the two units. Due to the narrow band width and especially due to the distortions occasioned in the video signal and the extreme difficulty of separating the video signal from the audio signal inside the equipment it is not advisable to transmit control signals over the coaxial cable along with the video signals. One of skill in the art is accordingly compelled to provide a separate line to transmit the control signals, which is undesirably expensive. The separate components in other types of consumer electronics-- high-fidelity sets with record players, compact-disk players, radio receivers, audio-cassette recorders, and amplifiers for example-- are connected by simple cable. When control signals must be transmitted along with music and speech, a separate line is also necessary for the aforesaid reasons.

The object of the present invention is accordingly to provide a means of transmitting information between two pieces of equipment connected by a cable without a separate line and without detriment to the transmission over the cable of either the information or the energy.

This object is attained in accordance with the invention, a cable with at least one core and at least one layer of insulation, in that the layer of insulation is made of optically conductive material and transmits the information optically.

The invention will now be described with reference to the drawings, wherein

FIG. 1 is a transverse section through a singlecore cable in accordance with the invention,

FIG. 2 is a longitudinal section through a cable in accordance with the invention with a connector at one end,

FIG. 3 is a longitudinal section through a cable in accordance with the invention with a connector at one end, and

FIG. 4 illustrates an information-transmission system comprising a video recorder, a television set, and a cable in accordance with the invention.

FIG. 1 is a transverse section through a single-core cable K in accordance with the invention. Its core A is made of wire and extends through a cylindrical, optically conductive layer I of insulation.

FIG. 2 is a longitudinal section through the cable K illustrated in transverse section in FIG. 1. One end is secured in a connector in the form of a plug VS. The outside of plug VS terminates in a tubular sleeve H that extends partly over cable K Extending along the axis of sleeve H is a pin S that is electrically connected to the core A of cable K. Between pin S and sleeve H is a tubular coupling L with a cross-section that preferably matches the cross-section of the layer I of insulation around cable K. Layer I of insulation can rest against optical coupling L but need not do so, because any space between the two components, although it might attenuate the optical connection, could not interrupt it.

The light, indicated by the arrows, travels from layer I of insulation into optical coupling L, emerges from its face, and enters for example the optical coupling of a jack VB that plug VS fits into and that can for example be accommodated in the housing of a piece of equipment.

The outside of the jack VB in FIG. 3 terminates in a sleeve H that extends partly over cable K. Extending along the axis of sleeve H is a cylindrical opening R that accommodates the pin S on plug VS and is electrically connected to cable K. Embedded between the cylindrical opening R that accommodates the pin S in plug VS is an also cylindrical optical coupling L. Its cross-section preferably matches that of the layer I of insulation on cable K. As with the plug VS illustrated in FIG. 2, the layer I of insulation on cable K can rest against optical coupling L but need not do so, because any space between the two components could not interrupt the optical connection. The light, indicated by the arrows, leaves the optical coupling L of the plug VS illustrated in FIG. 2 and enters the optical coupling L in jack VB, from the end of which it shines into the layer I of insulation on cable K.

Cable K can be secured in plug VS or jack VB by known, threaded, tension, or soldered connections. The pin S on plug VS is secured in the cylindrical opening R in jack VB by springs or by fitting tight, establish an electric contact between pin S and cylindrical opening R.

When, as illustrated in FIG. 2 for example, the light travels from the transparent layer I of insulation on cable K into optical coupling L, it is of advantage for the cross-section of coupling L to be larger than that of layer I of insulation to ensure that all the light leaving the insulation will be intercepted by the coupling.

If on the other hand the light travels from optical coupling L into the optically conductive layer I of insulation on cable K, it is of advantage for the cross-section of optical coupling L to be smaller than that of layer I to ensure that all the light leaving the coupling will be intercepted by the insulation.

If light is to be transmitted alternately in each direction, however, it will be more effective for the cross-section of optical coupling L to match that of layer I of insulation.

The information-transmission system illustrated in FIG. 4 represents one way of employing the cable in accordance with the invention.

A video recorder V is connected to a television set F by a coaxial cable K with a layer of insulation in the form of a dielectric that conducts light effectively in accordance with the invention. The ends of cable K are secured in plugs VS for example as illustrated in FIG. 2. Mounted on the components--video recorder V and television set F--are jacks VB that match plugs VS, which are also provided with an optical coupling facing the optical coupling L on plug VS. Connected to the end of the coupling in each plug VS opposite plug VS is an optical transmitter and/or receiver. The light from the optical transmitter in whatever component is transmitting travels through the optical coupling in the jack to the optical coupling on the plug, through coaxial cable KA, and through the optical coupling on the plug and the optical coupling in the jack on the receiving component. Both video recorder V and television set F can be provided with an optical transmitter, an infrared-emitting diode for example, and an optical receiver to allow the transmission of information in both directions.

Since the video signals are transmitted electrically and the control signals optically, they have no effect on each other and need not be separated in video recorder V or television set F. Finally, there is no need for two different cables to transmit information, each with a plug at each end and a jack on each component. A single cable is enough.

Another advantage is that optical transmission over the coaxial cable is not interfered with by infrared remote controls.

The cable in accordance with the invention, a combination of electric and optical cable, is not limited to the application described herein. The cable in accordance with the invention can be employed to simultaneously transmit information of any type both electrically and optically between any two components--repeaters, terminals, data banks, etc. for example.

In a ribbon-type cable for example, the individual wires can be insulated with an optically conductive material to provide as many optical-transmission channels as there are wires. Optically conductive insulation can also be employed in power cords and other cables that transmit energy to provide optical channels without increasing the cross-section of the cable. A power or energy cable will accordingly transmit not only electricity but also information of all types without one mode prejudicing the other.

The layer I of insulation around the cable can for example be divided into several mutually optically insulated transmission channels by longitudinal optically insulating intermediate layers to create several information channels without increasing the cross-section of the cable but considerably augmenting its transmission capacity.

If the cable in accordance with the invention is compared with a conventional cable of the same specifications and cross-section, the transmission capacity of the cable in accordance with the invention will be found to considerably exceed that of the known embodiment.