US2046475A - Sodium lamp - Google Patents

Description

y 1936- J. w. MARDEN ET AL SODIUM LAMP Filed June 22, 1934 2 Sheets-Sheet l BY G- MAW-57' July 7, 1936. J. w. MARDEN ET AL SODIUM LAMP Filed June 22, 1934 2 Sheets-Sheet 2 INVENTOR BY MF/STE/F ATTORNE I Patented July 7, 1936 warren STATES SODIUM LAlVIP John W. Mai-den, East Orange, and George Meister, Newark, N. J., assignors to Westinghouse Lamp Company, a corporation of Pennsylvania Application June 22,

9 Claims.

This invention relates to electric discharge tubes and relates more'particularly to a discharge chamber surrounded by a sealed envelope to provide the discharge with a heat insulating enclosure.

In co-pending application Serial No. 668,506 filed April 29, 1933 and assigned to the present assignee, a discharge lamp is shown and described in which a plurality of cold electrodes are em- 10 ployed in conjunction with a hot electrode or cathode. The construction shown and described is directed primarily to a sodium lamp operable on alternating current.

. It is well known that, when operating a lamp 18 such as that shown in the above identified pending application or other lamps'in which a metal solid at room temperatures is employed, it is nec- -essary to provide a structure in which means are employed for maintaining the necessary temper- 20 ature conditions to keep the sodium or other metal at a temperature necessary to maintain the vapor condition. I

Heretofore in devices of such character that it was necessary to conserve the heat from the discharge, it was the practice to enclose the discharge device in what was termed a vacuum bottle construction. This vacuum bottle form of enclosure was relatively expensive and required a double wall of glass and necessarily increased the size of a the device and made it difiicult to construct a lamp with a base in accordance with the common lamp practice.

The relatively large dimensions of the enclosure together with the dimculty in uniting or sup- 85 porting such an enclosure in proper relation to the discharge device, caused certain practical difflculties and it was not only a disadvantage from' an economical .and appearance standpoint, but

' made it necessary to increase the size of the base 40 and to provide means for supporting the vacuum bottle enclosure in-a base and to support the discharge device in proper relation to the enclosure.

In lamps employing a metallic vapor such as sodium it is dimcult t'o confine the vapor when condensed to portions of the device not in the effective path of the light rays.

It is desirable to keep the condensed sodium position to be quickly heated and vaporized. If the sodium becomes condensed in the ends of the bulb a considerable time is necessary to heat it for vaporization to obtain a good light. In accordance with the present invention means are employed for providing a relatively cool area on the bulb at one side adjacent to the electrodes so that any sodium that may condense during 1934, Serial No. 731,804

the operation 'of the lamp will become deposited on the cooled surface. This surface may be so positioned as to be in the rear of the lamp or adjacent to a reflector as when the lamp is mounted in a lighting housing. When the lamp cools ofi, the provided area being at the lowest temperature the sodium wfll condense thereon and be disposed in the most advantageous position for heating when the current is again turned on.

The above is accomplished by providing metallic contacts on the surface of the bulb so that heat is conducted away and the surface cooled. The same object may be attained by providing the bulb with a radiating fin formed of the glass but it has been found that a metallic strip or a plurality of metallic contacts give good results and are more practical from a manufacturing standpoint.

Although the above outlined feature is of particular advantage in connection with metallic vapor discharge devices generally, it is especially effective with a device constructed in accordance with the present device in which the discharge chamber is provided with a single enclosing envelope.

It is an object of the present invention to provide a lamp having a discharge chamber and an integral enclosing vacuum chamber.

Another object of the invention is to provide a discharge device consisting of a discharge chamber having an enclosing vacuum in an enclosing compartment sealed to said chamber.

Another object of the invention is to provide a discharge device comprising a chamber having means for supporting electrodes and an outer integral sealed envelope.

Another object of the invention is to provide a device of the character described in which the condensed vapor is confined to a predetermined area.

Another object of the invention is to provide'a metallic vapor discharge device with means for causing condensed vapor to deposit on such portion of the bulb as to be subjected to heat to facilitate starting of the device.

Other objects and advantages of the invention will be more fully understood by reference to the accompanying drawings in which Fig. 1 is a side elevational view of a device constructed in accordance with the present invention showing a double-walled envelope in section with electrodes supported therein;

Fig. 2 is a view taken on 'line lI-II in Fig. 1;

Fig. 3 shows a complete bulb constructed in accordance with the present invention and having a base applied thereto;

Fig. 4 is a modified form of the construction shown in Fig. 1 and discloses an inner discharge chamber supported by means of support members extending from a portion of the outer chamber;

Fig. 5 is a view taken on line V-V in Fig. 41;

Fig. 6 is a modified tubular form of the device in which an inner tubular chamber is supported concentric with an outer tubular envelope;

Fig. 7 is a, view taken on line VII-VlI in Fig. 6 and Fig. 8 is a modification of a support member shown in Fig. 4.

A lamp constructed in accordance with the present invention may comprise an outer sealed envelope l0, and an inner discharge chamber ill. The discharge chamber may contain electrodes l2i3 and l4-l5 and a cathode l6 asshown in Figs. land 3. This'construction is similar to that shown in the above mentioned copending application and will be more fully described hereinafter.

As shown, the sealed envelope may be of tubular form and have a reentrant tube or stem H. The chamber ll may also be of tubular form disposed concentrically within the envelope l8 and may be provided with a neck portion l8 fitting the reentrant tube II. A clamp collar I9 may be employed to grip the end of the neck and a pack ing ring 2! of suitable material as resilient ma-' terial to hold the chamber ll against endwise movement. Conductive support wires or members 2223 for the electrodes and similar wires 24-25 for the cathode may be sealed through a press 26 closing the reentrant tube ll.

The usual flexible conductors 20 may be connected to the support members for the supply of electrical energy from a suitable source (not shown). An exhaust tube 21 is provided for exhausting the device or the exhausting operation may be performed through a tubulature at one end of the bulb and tipped oif.

The chamber l I is provided with a quantity of sodium .or other vaporizable material or ionizable medium together with a gas for promoting initial ionization and the neck of this chamber is closed by a partition 28 cemented in place. This closure may be a disk of mica and serves to seal the chamber against the escape of the ionizable medium but need not be a seal of the character employed for the outer bulb l0 since the operation of exhausting the outer bulb may serve to exhaust the innerchamber. The inner chamber may. how- .1 ever, be exhausted and supplied with the metal vaporizable material before it is mounted in the outer bulb. When constructing a device such as shown in Figs. 1 to 3, the inner chamber is completed with its internal electrode structure and is mounted on the tube I! which is provided with a flange 29. This flanged tube and chamber II is then inserted into the bulb l0 and sealed at 3| to the neck portion 32 thereof. The bulb l8 may then be exhausted by means of the exhaust. tube 21 anda suitable base 33 secured tothe neck of the device in the usual manner, and a rare gas, as

for example, neon. may be admitted; The neon serves, in the chamber II, to cause the initial ionization as found desirable with devices of the present character. The neon gas enters the chamber II as well as the chamber II] but it has been-found that a metallic vaporizable material such as sodium does not escape into the outer envelope.

n the device shown in Figs. 1 to 3 electrical Y aoiaare energy may be supplied and the'eathode E6 is heated, the medium becomes vaporized and ionized resulting in a glow discharge. The initial ionization occurs between two starting tips 3:3

and 34'. The structure shown'is operable on alternating current and a discharge occurs between electrodes l3 and M and cathode lliduring one-half cycle and electrodes l2i5 and the oathode IG during the other half of the cycle. With this construction it is possible to operate with a current of relatively low density. With a current of say five amperes supplied. the two electrodes will receive the current and divide it and by reason of the relatively large surface area of the electrodes the current density is reduced per unit area.

The device shown in Fig. 4 employs two electrodes 35 and 36 and a cathode 31 enclosed in a chamber 38 of tubular form disposed concentri cally of a tubular sealed bulb or envelope 39. The bulb 39 is provided with a reentrant stem 4i through which lead wires 42-43 for electrodes 35 and 36 and lead wires 44-45 for the cathode 31' extend. Extending from the stem 4| and secured thereto by a clamp 41 is a rigid conductive rod 48 which connects with a terminal support 49 of the .cathode 31. Then another terminal support of the cathode is connected with a conductor 5| connected to lead wire 44.

The rod 48 is provided with a plurality of spacer members 53 which are clamped to the rod and contact with the outer surface of the chamber 38. The members 53 act as a cooling means and cause any condensed vapor to concentrate along the inner surface of the chamber adjacent to these members. If desirable the rod 48 may be made in the form of a T-bar 54, as shown in Fig. 8, to

provide a continuous contacting surface 55 along the chamber.

\ The chamber may be closed at its ends by walls 56 and 51 of any suitable material such as mica.

The chamber may be held in a collar 58 and a split collar 58 both of which may be secured to the rod 48.

The device just described may be constructed by first mounting the chamber 38 on the reentrant tube 4| and then sealing the flange of this tube to the end of the bulb 39.

Figs. 6 and 7 show a device in which a sealed envelope 6l is provided with a concentrically disposed chamber 62 of tubular form. In this device electrodes 82 and 63 are disposed at one end of the chamber with conductive support members 65 and 66 within the chamber. chamber 62 is arranged to slip over a reentrant One end of the tube 61. A split ring 68 clamps the end of the chamber and a packing 69 to hold thechamber against endwise movement. The chamber may be closed at one end by a wall H which rests on the upper end or press portion 12 of the reentrant stem. The other end of the chamber may be closed by a wall continuous with the side or tubular wall.

It is to be understood that the bulb chamberschamber and bulb may be adjusted so that heat dissipation is controlled to maintain the temperature within the desired range.

Whereas heretofore it was necessary to employ a cumbersome and outer vacuum bottle type of heat insulative material the present invention provides a simple construction which is more readily applied to housings such for example as employed for street lighting or in work rooms where it is desirable to avoid the installation of large size units.

Although a preferred embodiment of the in-' vention is shown and described herein it is to be understood that modifications may be made therein without departing from the spirit and scope of the invention as set forth in the appended claims.

What is claimed:

1. A discharge lamp comprising a chamber having a neck portion, means for producing a glow discharge within said chamber, a sealed envelope enclosing said chamber, a reentrant tube in said envelope said tube extending into the neck portion of said chamber for supporting said chamber and a partition separating said tube from said chamber.

2. A discharge lamp comprising a sealed envelope, support wires sealed through a wall of said envelope, electrodes mounted on said support wires, a chamber closed at one end enclosing said electrodes, a tubular portion integral with said envelope and extending interiorly thereof, the other end of said chamber being closed by said tubular portion, and a partition between said tubular portion and said chamber.

3. A discharge lamp comprising a sealed envelope,-a tubular stern in said envelope, conductive support wires sealed through said stem, elec trodes mounted on said support wires, a chamber enclosing said electrodes, a sleeve integral with said chamber disposed about said stem anda partition separating said sleeve from said chamber.

4. A discharge lamp comprising a sealed envelope, a reentrant tube integral with said envelope, a plurality of electrodes supported from said tube, a bulb enclosing said electrodes, said bulb having a constricted neck portion fitting said tube.

5. A discharge lamp comprising a sealed envelope, a reentrant tube integral with said envelope, a plurality of electrodes supported from said tube, a bulb enclosing said electrodes, said bulb having a constricted neck portion fitting said tube and means for clamping said neck portion on said tube.

6. A discharge lamp comprising a. sealed envelope, conductive support wires sealed through a wall 0! said envelope, a chamber within said envelope, a metallic vapor within said chamber, electrodes mounted on said support wires and disposed at one end of said chamber, a cathode in said chamber at the opposite end thereof, a conductive support member for said cathode extending along the outer side of said chamber and means supported by said support member for confining condensed metallic vapor to a given area.

'7. A discharge device comprising a sealed en- 7 velope, a plurality of electrodes in said envelope,

a metallic vapor within said envelope, a member for maintaining a portion of the envelope relatively cool to condense said vapor in a re- 2 stricted area on the surface of said envelope and a conductive member for one of said electrodes supporting said member.

8. A discharge device comprising a sealed envelope, a plurality of electrodes in said envelope, a metallic vapor within said envelope, a member for cooling given portions of the surface of said envelope to cause condensed vapor to be confined to said portions and a conductive member for one of said electrodes disposed adjacent to the outer' surface of said envelope supporting said first mentioned member.

9. A discharge device comprising a sealed envelope, a plurality of electrodes in said envelope, a metallic vapor within said envelope a conductive member for one of said electrodes and metallic members carried by said conductive member and disposed in contact with the surface of said envelope to provide a relatively cool area tor the deposit of condensed vapor.

JOHN W. MARDEN.

- GEORGEJMEISTER.

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