CA1322118C

CA1322118C - Electricity-light transmitting composite wire

Info

Publication number: CA1322118C
Application number: CA000560313A
Authority: CA
Inventors: Kazuo Sawada; Hajime Hitotsuyanagi; Kengo Ohkura
Original assignee: Sumitomo Electric Industries Ltd
Current assignee: Sumitomo Electric Industries Ltd
Priority date: 1987-03-05
Filing date: 1988-03-02
Publication date: 1993-09-14
Anticipated expiration: 2010-09-14
Also published as: JP2584476B2; JPS646308A; DE3883558T2; US4842366A; EP0281133A1; EP0281133B1; DE3883558D1

Abstract

ABSTRACT OF THE DISCLOSURE
A ceramic type superconductive layer (2) is formed on the outer peripheral surface of an optical fiber (1), and a stabilizing layer (3) is formed so that it contacts the outer peripheral surface of the superconductive layer (3).
The diameter of the optical fiber is, for example, not more than 100 µm. The superconductive layer may be formed with a spirally extending groove (7) which divides the superconductive layer.

Description

` - 1 3 ~
, TITLE OF THE INVENTION ~ .
F.lectricity-Light Transmitting Composite Wire BACKGROUND OF THE INVENTION
Field of the Invention This invention relates to an electricity-light transmitting composite wire for transmitting both electrical energy and optical signals.
Description o~ the Prior Art Heretofore, in the~field of power transmission, composite of optical fiber and electric wire have been used. In a typical construction, an optical fiber unit formed by gathering~a suitable number of optical fihers is positioned at the center and a pluxality of metal strands are twisted together around said optical fiber unit.
At present, such composites of optical fiber and electric wire~are~limited in use to the field of power transmissio~. It seems that the reason is that composite wires having optical fibex and electric wire compounded together are highly rigid and hence hard to handle and are not so compact in form. Therefore, in the field of power distribution including connection between two parts, they cannot be used as such.
As is known in the art, optical fiber has the merit of being capable of transmitting an extremely high density optical signal despite the fact that it is compact in .

. : :: : .... : ., ~ .. ; :: -:

~322~18 form. In contrast, in the case of electric wire, when it is desired to transmit high electric energy or to transmit electric signals or the like over a long distance without sufering much attenuation, it is necessary to correspondingly increase the cross-~ectional area of the electric wire. Therefore, in a COmpQSite wire of optical fiber and electric wire, if a compact form is to be attained, this involves a reduction in the cross-sectional area of the wire section, entalling a reduction in the amount o~ electric energy which can be transmitted or attenuation of electric signals to be transmitted.
SUMMARY OF THE IN~ENTION
Accordingly, this inven~ion is intended to provide an electricity-light transmitting composite wire which is capable of ~ransmitting optical signals and electric energy in a high density manner.
An electricity-light transmitting composite wire according to this invention includes a light transmitting body mean~, such as an optical fiber, to tran~mit optical signal~, and ~ ceramic type ~uperconductor which exhibits superconductive phenomena at an operat.ing temperature and which is compounded with ~aid li~ht transmitting body means.
The compounding manners include one in which the light ~ran~mitting body and the superconductor are ... -. ..... ,, . ,. ~, , . ~ . , 13221~ g compounded in a concentric construction and another in which they are compounded in a planar laminated construction.
In this invention, the transmission of optical signals is undertaken by the light transmitting body, while the transmission of electric eneryy or electric signals is effected by the superconductor.
Thus, according to the invention, the transmission of optical signals in a h1gh density manner is realized by the light transmitting body, while in the superconductor, electric resistance can be made zero, so that even if the cross-sectional area is small, high electric energy or accurate electric signals can be transmitted; such electricity~light transm1tting composite~wire can be constructed in compact fcrm.
Therefore, the field of application is widened to the extent that it is applicable not only in the field of power transmissicn but also in the field of power distribution including connection between parts, and since it is made compact in form, it is easier to handle.
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In a preferred embodiment, a stabilizing member is inccrporated which ccntacts the superconductor to stabilize the superconductive state.
As for the superconductor, it is preferable to use one whose critical temperature is higher than 77 K
.

_ 3 _ ~322118 (absolute temperature). Thereby, it becomes possible to use liquefied nitrogen t77 K3, which is inexpensive, as a refrigerant. Further, there would be a possibility of using a superconductor which exhibits superconductive phenomena at a temperature in the vicinity of normal temperature. Thereby, the refrigerant can be dispensed :
with, and the composite wire can be prevented from becoming increased in size owing to the refrigerant passage or it becomes possible to use an inexpensive safe refriyerant, such as water.
The superconductors which exhibit relatively high critical temperature described above include a group which is represented by the general formula AaBbCc ~where a, b : and c are numbers indicating the proportions of : 15 composition of A, B and C, respectively~, wherein A is at least one member selected from the group consisting of the group Ia, IIa and IIIa elements in the periodic table, B
is at least one member selected from the group consisting o~ the group Ib, IIb and IIIb elements in the periodic table, and C is at least one member selected from the group consisting of oxygen, carbon, nitrogen, fluorine and sulfux. In the above general formula AaBbCc, it is preferable that the relation a x (average molecular weight of A) + b x (average molecular weight of B3 = c x (average molecular weight of C) hold. Presumably, a ceramic type 1~221~8 superconduc~or having a relatively high critical temperature would have a layer-Iike perovskite t~pe crystalline structure.
In addition, as for tha group Ia elements in the 5 periodic table, mention may be made of H, Li, Na, K, Rb, Cs and Fr. As for the group IIa elements in the periodic table, mention may be made of Be, Mg, Ca, Sr, Ba and Ra~
As for the group IIIa elements, mention ma~ be made of Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, 10 Lu, Ac, Th, Pa, U, Np, Pu, Am, Cm, Bk, Cf, Es, Fm, Md, No and Lr.
As for the group Ib elements in the periodic table, mention may be made of Cu, Ag and Au. As for the group IIb elements in the periodic table, mention may be made of 15 Zn, Cd and Hg. As for group IIIb elements, mention may be made of B, Al, Ga, In and T1.
As for the A in the above-mentioned general formula AaBbCc, preferably it is at least two members selected from the group consisting of the group Ia, IIa and IIIa 20 elemen~s in the periodic table. Further, preferably, the B contains at least copper, and the C contains at least oxygen.
These objects and other objects, features, aspects and advantages of the present invention will become more 25 apparent from the following detailed description of the d 1 3 ~

present invention when taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is an enlarged sectional view showing an embodiment of the invention;
Fig. 2 is an enlaxged sectional view showing a , .
stabilizing layer 3 and a pipe 5 added to ~he electricity-light transmitting composite wire shown in Fig. l;
Fig. 3 is a front view showing spiral groves 7 formed in a superconductor layer 2;
Fig. 4 is an enlarged sectional view showing another :
embodiment of the invention; and Fig. 5 is~an enlarged sectional view showing a ; 15 further embodiment of~the~invention. ~
DESCRIPTION OF THE PREFERRED EMBODIMENTS
E~bodiments of the invention will now be described with ~eference to the drawings.
First, an optical fiber 1 having a diameter of 0.5 mm and formed of quartz or fluoride glass, as shown in an enlarged seational view ln Fig. l, is prepared, and lt is coated with~a 0.2 mm-thick superconductive layer 2. This superconductive layer 2 is made form a ceramic type supercsnductive~material having a composition such as, for example, (La, Ba)2CuO4, (La, Sr)2CuO4 or YBa2Cu3O7_x.
: ~ :
' ~32211~ ~

Such superconductive layer 2 can be formed as by gas phase process, such as sputtering or CVD, or by the so-called sol-gel process involving condensation of alkoxide.
In addition, a protective layer (not shown) for the optical fiber 1 may be formed between the optical fiber and the super conductive layer 2.
The electricity-light transmitting composite wire 10 shown in Fig. 1, though thin as a whole, is capable of transmitting optical siynals and electric energy in the form of power or electric signals in a hi~h density manner or in large amounts.
Fig. 2 is an enlarged sectional view showing other ,, components added to the composite wire 10 shown in Fig. 1.
;~ ~ First, the superconductive layer 2 is coated with high purity copper or aluminum, for example, so as to ~orm a stabilizing layer 3 ~or stabilizing the superconductive state of~the superconductor which forms the super conductive layer 2. And the structure starting with the optical fiber 1 and ending in the stabilizing layer 3 is received 1n a pipe 5~with a sui~able clearance 4 defined therebetween. The clearance 4 serves as a passage for a refrigerant~6 used to cool the superconductor which forms the superconductive layer 2 to its critical temperature to put it in the su~erconductive state. The pipe 5 itself is : ~
preferably formed of a heat insulating material or is ,. .. , , ,., .. i~

132211~

coated with a separate heat insulating material (not shown). Further, the pipe 5 performs the function o protecting the optical fiber 1 and the superconductive layer 2.
In the description of the above embodiment, the diameter o~ the optical fiber 1 is 0.5 mm and the superconductive layer 2 is formed thereon; however, tb provide magnetic stabilization o~ the superconductor ~orming the superconductive layer 2, it is preferable to reduce the diameter of the optical fiber 1, for example, to not more than 100 ~m.
As fox the means for magnetically stabili7.ing the super onduct~ve state o~ the superconductive layer 2, besides the measure of making the diameter of the optical ~iber 1 relatively small, a number of spirally extending grooves 7, as shown in Fig 3, may be formed in the superconductive layer 2 to divide the latter. The dividing of the superconductive layer 2 shown in Fig. 3 may, of course, be ef~ected concurrently with reducing the diameter of the optical fiber 1 to not more than 100 ~m as described above.
Fig. 4 is an enlarged sectional view showing another : embodiment of the invention. The compounding manner of the composite wire 10 shown in Fig. 1 is such that the light transmltting body (optical fiber 1) and the . ~

. , , 1322~.18 superconductor (superconductive layer 2) are compounded in a concentric construction. In the embodiment shown in Fig. 4, however, the light transmitting ~ody and the ;~
superconductor are compounded in a planar laminated construction.
That is, the electricity-light transmitting composite ;
wire 20 s~own in Fig. 4 has a lisht transmitting tape 11 serving as a light transmitting body, and a superconductive layer 12 laminated thereon. In addition, the material of the light transmitting tape 11, and the material of the superconductive layer 12 and the method of producing the same can be made the same as in the electricity-light transmitting composite wire 10 shown in Fig. 1. ;
Fig. 5 is an;enlarged sectional view showing a further embodiment of the invention.
In the~electricity-llght transmitting composite wire 30 shown therein, a reinforcing member 22 formed with a plurality o~ grooves 21 is disposed at the center. The xeinforcing member 22 is made, for example, of fiber-reinforced plastic or metal. The grooves 21 are foxmed so that they extend spirally on the outer peripheral surface of the xeinforcing member 22. The reinforcing me~ber 22 is received in a pipe-like sheathing member 24 with a suitable clearance 23 defined - , , . . ~. , ~ ,, ,. ., .. - .

, . , . - , : . . . .
.. , ~ , " ~22~18 therebetween. the clearance 23 serves as a passage for a refrigerant 25 used to cool a superconductor (to be later described) to its critical temperature to put it in the superconductive state.
s In addition, if the rein~orcing member 22 is made of metal, it itself can be used as a conductor. Further, if a superconductor to be later described is disposed in cont~ct with the reinforcing member 22 while forming the latter of high purity copper or aluminum, then the r~inforcing member 22 can be made to function as a stabilizing member for stabilizing the superconductive state of the superconductor.
In the composite wire 30 shown in Fig. 5, there are two possibilities concerning wires denoted by the reference numeral "26" and disposed in the grooves 21 of the reinforcing membex 22.
The first possibility is that each wire 26 is in the form of the electricity-light transmitting composite wire 10 shown in Fig. 1. The second possibility is that some of the wires 26 are formed of optical ~iber while the others are in the form of wires made of ceramic type superconductor itself. In either case, electric enersy or both electric and optical signals can be transmitted.
In the prev.ious description relating to Fi~ (La, Ba)2CuO4, (La, Sr)2Cu04 and YBa2Cu307_x have been given as . . . ~ .:
., - .

i3~2118 examples of the composition o~ the superconductor. In this connection, it has been found that a superconductive material which belongs to the third example, or a Y-Ba-Cu-O type superconductor and which has the ~ollowiny composition exhibits a-higher critical temperature.
Respective powders of Y2O3, BaCO3 and cuO were mixed together so that the ratio Y : Ba : Cu was 1 2 : 3, and the mixture was then preliminarily sintered. Thereafter, this prelimlnarily sintered body was crushed, molded at a ~
10 pressure of 100 bar and ~ired at 940C in the air for 24 ;
hours. The sintered body obtained by such firing exhibited symp~toms of superconduction at 90 K. Thus, if ~ Y
this ceramic ty~e superconductive material is used as the superconductive material contained in the superconductive layer 2 or 1~ or the wires 26, extremely high operating :: :
temperat~re is available.
In addition, in the composite wire 10 shown in Fig.
1, the superconductive layer 2 has been located outwardly of the optical fiber 1. However, as another embodiment of the invention, the posltional relation between the superconductor and the light transmitting body may be reversed.
Further, in~Figs. 1 ~nd 4, a single light transmitting body and a single superconductor have been ~ 11 --.. . : -; . :: ~ - :
.. :, : .
- ~ ~ . : .

formed; however, each component may have a laminated construction comprising a plurality o~ layers.
Although the present invention has been described and illustrated in detail, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation, the scope of the present invention belng limLted only by the terms of the appended claims.

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Claims

1. An electricity-light transmitting composite wire comprising a light transmitting body means (1, 11, 26) and a ceramic type superconductor (2, 12, 26) exhibiting superconductive phenomena at an operating temperature, characterized in that the superconductor is of a ceramic type represented by the general formula AaBbCc (where a, b and c are numbers indicating the proportions of composition of A, B and C, respectively), wherein A is at least two members selected from the group consisting of the group Ia, IIa and IIIa elements in the periodic table, B is at least one member selected from the group consisting of the group Ib, IIb and IIIb elements in the periodic table, and C is at least one member selected from the group consisting of oxygen, carbon nitrogen, fluorine and sulfur, wherein said B includes copper, and said C includes oxygen, and wherein said superconductive body has a layer-like perovskite structure; said superconductor including a superconductive layer (2) on the surface of said light transmitting body means.

2. The electricity-light transmitting composite wire of claim 1, wherein said light transmitting body means includes an optical fiber (1) of a diameter of not more than 100 µm.

3. An electricity-light transmitting composite wire as set forth in claim 2, wherein said superconductive layer (2) is formed with a groove (7), whereby said superconductive layer is divided.

4. An electricity-light transmitting composite wire comprising a longitudinally extending reinforcing member (22), and a plurality of separate wires (26) disposed on said reinforcing member, wherein at least one of said wires is an electricity-light transmitting composite wire as set forth in any one of claims 1 to 3.

5. An electricity-light transmitting composite wire as set forth in any one of claims 1 to 3, further including a stabilizing member (3) contacting said superconductor means (2) for stabilizing the superconductive state of said superconductor means.

6. An electricity-light transmitting composite wire as set forth in any one of claims 1 to 3, further including pipe means (5, 24) which receive said superconductor body means and provide a refrigerant passage.