US1417287A - Copper conductor for electric-lamp bulbs and other vacuum tubes - Google Patents

Description

T. YANAI. COPPER CONDUCTOR FOR ELECTRIC LAMP BULBS AND OTHER VACUUM TUBES.

APPLICQHON FILD MAY 29, I918- 1,417,387.

Patented my23,1922.

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ATTY- I in glass rods and UNITED STATES PATENT OFFICE.

TEIZO YANAI, OF TOKYO, JAPAN, ASSIGNOR TO NIHON DENKI KOGIJ'O KABUSHIKI KAISHA, OF TOKYO, JAPAN.

COPPER CONDUCTOR FOR ELECTRIC-LAMP BULBS AND OTHER VACUUM TUBES.

Application filed May 29,

Tokyo, Japan, have invented new and use ful Improvements in Copper Conductors for Electric-Lamp Bulbs and Other Vacuum Tubes, of which the following is a specification.

This invention relates to leading-in conductors of electric lamp bulbs and the like, which consists of slender copper tubes sealed to a process of forming such conductors. The object of this invention is to obtain a cheap substitute for platinum which is usually employed for the purpose, by the use of a copper conductor which is made hollow, the conductor being thus made somewhat flexible and crevices being prevented from appearing between the conductor and the glass rod in which it is sealed, due to difference of the coefiicient of expansion of copper and glass.

In the accompanying drawings, Fig. 1 shows a tube formed by windmg or bending a long thin skelprof copper, and Fig. 2 shows copper tubes sealed in a glass rod in accordance with this invention.

Hitherto there have. been incandescent electric lamps and other vacuum tubes with leading-in conductors of copper, but in such bulbs and vacuum tubes, although the surface of the conductors and the glass rods tightly stick together, there a drawback of their not perfectly maintaining vacuum, crevices being formed, "when subjected to changes of temperature between the copper wire and the glass rod due to the difference of coeflicients of expansion of the two. The present invention is an improvement on the above, and consists in the use of copper wire which is made hollow, thus a certain degree of flexibility being given thereto and the separation of the wire from the glass being effectively prevented notwithstanding the strain caused between the two when subjected to change of temperature due to differences in their coefficients of expansion.

The following is an example of one man- Specification of Letters Patent.

Patented May 23, 1922.

1918. Serial No. 237,183.

nor in which my invention may be put into prac-tlce Take a thin copper wire and press part of 1t fiat and thin by a roller or any other suitable means. Bend this flattened part 1nto a tube, joining the edge (1) with the edge (2), as shown in Fig. 1, and leaving vacant place (3) within. A conducting wire 6 formed of any suitable material is now inserted into the tubular portion, whereupon the front end 5 thereof is pressed toward the wire 6 so that the tubular portion is closed. The tube and wire are now inserted into the glass wall of the bulb, whereupon the glass is subsequently heated to a semimelted condition. The heating is continued for a while and the glass rodis pressed flat as far as the hollowness of the copper tube is not interfered with. Thus the copper tube is hermetically sealed, and a glass rod with hollow space within, which hollow space being surrounded by copper, is formed.

I am aware that before this invention there is known a leading-in wire of metal tube used with vacuum containers such as vapor lamps or vapor rectifiers through which a large amount of electric current passes; but such leading-in wire cannot practically be used with ordinary incandescent lamp bulbs. Now, according to my invention, a'copper tube is formed by bending one edge of a thin narrow strip of that metal over the other edge, and a very slender tube can very easily be formed by simply passing a very narrow thin strip through'a die.

I claim A leading-in conductor for vacuum containers comprising a single length of material having a slit tube formed integral therewith at one end thereof, the longitudinal edges of said tube overlapping, and a wire closing the open end of the tube. y

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

TEIZO YANAI.

Witnesses:

' H. F. ALTMANs, YOSHIO lKAWADA.

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