US2336923A

US2336923A - Glow switch

Info

Publication number: US2336923A
Application number: US405921A
Authority: US
Inventors: Walter E Carpenter
Original assignee: Westinghouse Electric and Manufacturing Co
Current assignee: CBS Corp
Priority date: 1941-08-08
Filing date: 1941-08-08
Publication date: 1943-12-14
Anticipated expiration: 1960-12-14

Description

Dec. 14, 1943.

w. E. CARPENTER GLOW SWITCH Filed Aug. 8, 1941 lNVENTOR LEE/V727? ATTORNEY Patented Dec. 14, 1943 GLOW SWITCH Walter E. Carpenter, West Caldwell,

N. J., as-

signor to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania Application August 8, 1941, Serial No. 405,921

Claims.

The present invention relates to gaseous discharge devices and more particularly to such a device as is now known to the art as a gaseous relay for the starting of fluorescent lamps.

In a device of this character a glow discharge is first established between the electrodes and since one of the electrodes is a bimetallic element, it deflects under the heat of the discharge into contact with the other electrode to shortcircuit the discharge and complete a circuit to the lamp for the purposes of starting the latter. However, the disadvantages of glow switches of the prior art has resided in the fact that engagement of the electrodes has not lasted long enough for the lamp to be properly conditioned for starting because the bimetallic electrode of the glow switch cooled too quickly and returned to its normal separated position.

It is accordingly an object of the present invention to provide a glow switch wherein a desired time lag is provided during which the electrodes remain in engagement with each other following extinguishment of the glow discharge and the cessation of heat generation.

Another object of the invention is to provide for production of the desired thermal lag in the operation of the switching electrodes of the gaseous relay by concentrating the heat of the glow discharge upon one of the electrodes at such a region thereof that for a second or two after the glow has ceased, the heat will flow from this superheated portion to the cooler portion of the electrode where most of the operating flexure will occur, thereby keeping the contacts closed for the desired longer period.

A further object of the invention is to increase the superheating of the switching electrode by producing at the region of superheat a crater of the general type disclosed in U. S. Patent No. 2,251,568, issued August 5, 1941, to D. S. Gustin et a1. and assigned to the same assignee as the present invention.

Among other ancillary objects of the invention is the provision of a bipartite electrode of the known U-shaped or bent bimetal type, and the provision thereon of such a crater, situated at a portion of the free leg of the bimetal which is remote from the region of maximum bend, in order to localize the superheat at a region where the transference of heat by conduction to the cooler portion of the bimetal, where most of the bending occurs, will maintain the flexed condition thereof, prolonging the contact during which the heating current from the source flows with an exhaust stem Iii,

through the thermionic charge lamp.

Still further objects and features of the present invention will become clear to those skilled in the art by reference to the accompanying drawing, wherein:

Fig. 1 is a vertical sectional view of a gaseous electric relay device, showing in perspective switching electrodes in the construction of which the present invention has been embodied; Fig. 2 is a fragmentary detail view in side elevation of the switching electrodes taken apart from the container and illustrating the open position or the switch; and Fig. 3 is a similar fragmentary detail view showing the switching electrodes in their closed position.

Referring now to the drawing in detail, the reference character l3 designates generally a gaseous electric relay device of the general type intended to be used in conjunction with a discharge lamp in such a system as that illustrated in detail in Letters Patent Nos. 2,200,443 and 2,228,210 and to which reference may be had for a more complete description of this system. The system, as such, has not been illustrated in the drawing herein, for the reason that such systems are now well known to those skilled in the art, and constitute merely illustrative examples of one application of the improved gaseous electric relay device herein disclosed and claimed.

The gaseous electric relay device, as shown in Fig. 1, comprises an envelope or container M which after evacuation is filled with an ionizable gas such as helium, neon or the like, at a pressure approved in practice, which may be approximately thirty millimeters, depending upon the particular line voltage, and at the voltage of the customary commercial source or volts, the pressure approximates fiiteen millimeters. The device has a reentrant press portion is provided as customarily employed in the fabrication of incandescent lamps, and a suitable base (not shown) may be provided, if desired.

A pair of leading-in conductors ll and it are sealed into the reentrant press, and interioriy of the envelope a supporting post is, connected electrically with the conductor ii, is provided, forming one or the interior contact terminals 01 electrodes in the displate 28 of nickel, iron, molybdenum or the like, coated with an electron emissive material such as the oxides of barium, strontium, etc.

The other electrode comprises a U-shaped bimetallic strip 25 having its high expansive side 22 on the inside of the bend, this electrode being welded or otherwise rigidly secured to a post 23 extending -lrom the press it, within which it has electrical connection with the conductor iii. This electrode is of a bipartite form, one of its parts being made of a strip of metal 2% connected firmly, as by the clamping fingers 25, to the lower end 2% of the bimetal, within which it eX- tends inwardly and upwardly around the bend, as at 2'5, and then downwardly, in the form of a free leg 23, past the region at which the contact terminal 29 of the bimetal leg 3% is adapted to be engaged with the contact terminal it hereinbefore mentioned.

Ihe strip 25 may desirably be made of zinc in the event that helium is used as the ionizable gas, but this is not intended to exclude the use of other suitable materials and gases. For example, the strip 2 may be made of magnesium in the event that neon is utilized as the ionizable gas.

The bimetal is coated with an electron emissive substance adapted to emit a copious new of electrons, and the electrodes 2d and 32 are oper able to initiate a glow discharge therebetween in known manner upon the application thereto of a suitable potential by means of the conductors I? and it, which derive the same from a current source such as that shown in the patents above enumerated.

A crater ti is provided in the surface of the electron emissive strip near the end 2% thereof for concentrating the discharge therein to cause rapid heating of the adjacent bimetal electrode leg and in pursuance of an important feature of the instant invention this crater is disposed, as shown, at a region remote from the bend so that the superheat induced at the crater by the glow discharge continues to affect the bend 2i and thus maintain the leg 36 in the position shown in Fig. 3, keeping the contact terminals is and it closed, and affording a period of prolonged duration during which heating current may pass through conductors H and E8 to the thermionic electrodes of the discharge lamp, as in the systems of the above-mentioned patents.

Referring to Figs. 2 and 3, it will be understood that as one or both of the opposed surfaces of the members 263 and 3B are electron emissive, the glow will be developed therebetween and the member so will swing away from the member 2 under the action of the heat thus engendered, making the contact between the contact point 255 and the terminal Hi.

This will be effected with relative rapidit for the reason that there is what may be called a region of superheat developed within the concave side of the crater 3 l and this concentration of heat radiates from the crater against the high expansive side 22 of the member 39. This superheat is dissipated with relative slowness along the member 33, and helps to maintain the bimetal in its Fig. 3 position for an unusually long duraion of time, and thus retards the'breaking of contact at Zt-l 9 long enough to permit the lamp electrodes to heat up to the desired operating temperature.

It accordingly becomes clear to those skilled in the art that a gaseous electric relay device is herein provided with an improved construction and arrangement of the switching elements, the operation of which affords a thermal lag between the making and breaking of the heating circuit, with a consequent heating period of adequate duration to bring the thermionic electrodes up to the temperature required for their most efficient action in striking the arc in the partially ionized gas between these electrodes of the lamp; also that the relay of this improved construction is adapted for use in any field in which it may be employed advantageously by reason of the nature of the improvements herein disclosed.

It will be clear further that the disposition of the crater at a region remote from the bend of a U-shaped bimetal, to concentrate superheat upon the end of a leg coated with the electron emissive substance, causes the crater to cooperate with the other structural features above disclosed to accomplish the-objects set forth in the opening paragraphs of this specification.

Although but one embodiment of the present invention has been herein shown and described, it is to be understood that modifications thereof be made without departing from he spirit and scope of the appended claims.

claim: A gaseous electric relay device for completan electri circuit comprising an envelope l. vided with an ionizable medium therein and air of electrodes between which a glow disarge occurs upon the application of a potenal thereto, one of said electrodes being a heatsponsive element having parts separable durlg operation to be heated by the discharge and operable to deflect into engagement with the other of said electrodes to short-circuit the same and extinguish said discharge and to complete said circuit, and means carried by said heatresponsive electrode remote from the axis of defiection thereof to provide a location of concentrated heat from the discharge and from which location heat is transmitted to the axis of deflection of the heat-responsive electrode after extinguishment of the discharge to cause separation of said heat-responsive element and a prolonged time delay in the engagement of the electrode prior to their complete separation following cooling of said heat-responsive electrode.

2. A gaseous electric relay device for completing an electric circuit comprising an envelope provided with an ionizable medium therein and a pair of electrodes between which a glow discharge occurs upon the application of a potential thereto, one of said electrodes being a U-shaped heatresponsive element having parts separable durmg operation to be heated by the discharge and operable to deflect about an axis adjacent the base thereof until its free end engages the other of said electrodes and short-circuits the same with extingulshment of the discharge and completion of said circuit, and means carried by the free end of said heat-responsive electrode remote from the axis of deflection thereof to provide a location of concentrated heat from the discharge which continues to transmit heat to the axis of deflection of said heat-responsive electrode after extinguishment of the discharge to cause separation of said heat-responsive element and a prolonged time delay in the engagement of said electrodes prior to their complete separation following cooling of said heat-responsive electrode.

3. A gaseous electric relay device for completing an electric circuit comprising an envelope provided with an ionizable medium therein and a pair of electrodes between which a glow discharge occurs upon the application of a potential thereto, one of said electrodes being a heat-responsive bipartite element including a metallic strip and a superimposed bimetallic strip to be heated by the discharge end operable to cause defiection of said bimetallic strip away from said metallic strip into engagement with the other of said electrodes to short-circuit the same and extinguish said discharge and to complete said circuit, and means carried by said heat-responsive electrode adjacent the end of said bimetallic strip and remote from the axis of deflection of the latter to provide a location of concentrated heat from the discharge which continues to transmit heat to the axis of deflection of said bimetallic strip after extinguishment of said discharge to cause a prolonged time delay in the engagement of the bimetallic strip with the other of said electrodes prior to its separation and return to superimposed position with said metallic strip following cooling of said heat-responsive elec trode.

4. A gaseous electric relay device for completing an electric circuit comprising an envelope provided with an ionizable medium therein and a pair of electrodes between which a glow discharge occurs upon the application of a potential thereto, one of said electrodes being a heat-responsive bipartite element including a metallic strip and a superimposed bimetallic strip to be heated by the discharge and operable to cause deflection of said bimetallic strip into engagement with the other of said electrodes to short-circuit the same and extinguish said discharge and to complete said circuit, and a crater provided in the end of said metallic strip adjacent said bimetallic strip and remote from the axis of deflection of the latter to provide a location of concentrated heat from the discharge which continues to transmit heat to the axis of deflection of said bimetallic strip after extinguishment of said discharge to cause a prolonged time delay in the engagement of the bimetallic strip with the other of said electrodes prior to its separation and return to superimposed position with said metallic strip following cooling of said heat-responsive electrode.

5. A gaseous electric relay device for completing an electric circuit comprising an envelope provided with an ionizable medium therein and a pair of electrodes between which a glow discharge occurs upon the application of a potential thereto, one of said electrodes being a heat-responsive bipartite electrode of normally superimposed elements one of which is of bimetal anchored at one end and the other element of which is supported by said bimetallic element, and said bimetallic element being free to deflect under the heat of the discharge into engagement with the other of said electrodes to short-circuit the same and extinguish said discharge and to complete said circuit, and a crater provided in the end of said other element adjacent the free end of said bimetallic element to provide a location of concentrated heat from the discharge which continues to transmit heat to the axis of deflection of said bimetallic element after extinguishment of said discharge to cause a prolonged time delay in the engagement of said bimetallic element with the other of said electrodes prior to its separation and return to superimposed position with said other element following cooling of said heatresponsive electrode.

W ALTER E. CARPENTER.