US2412883A - Starting switch - Google Patents

Description

Dec. 17, 1946. F. P. GASSER 2,412,883

STARTING SWITCH Filed April" 1e, 1943 IN V EN T 0R. Haq/wf P 64556K A TTOQNEY Patented Dee. 17, 1946 2,412,883 STARTING SWITCH Frank P. Gasser, Bever] to Gasard Patents Inc poration of New York Application April 16, 1943, Serial No. 483,253

4 Claims.

This invention relates to starting switches for electric discharge lamps. More particularly the invention pertains to a switch of the character described in which at least one of a pair of contacts is carried by a bimetallic element.

Fixtures for fluorescent electric discharge lamps are usually provided with sockets for starting switches. These sockets are so arranged in the fixtures that both the diameter and height of the switches are limited to small dimensions. As a result, much dimculty has been experienced in so designing the switches that, despite their small size, the starting contacts may be rapidly opened after the lamp laments have been raised to incandescence in order to quench sparking more rapidly and obtain a maximum surge voltage.

Another difficulty has been that the distance between the bimetallic strip and the heating means therefor changed during operation of the switch and adversely affected the heat transfer. Heretofore, complicated congurations of the strip have been resorted to for overcoming such diiiculty, but these congurations have considerably increased the manufacturing and assembly costs of the switches.

It is an object of my invention to provide an improved switch of the character described in which the bimetallic element is so shaped and the heating means so constructed and arranged relative to the bimetallic element that the con- -tact without aiecting heat transfer.

Another object of my invention is switch of the character described to provide a which comprises relatively few and simple parts, is easily fabricated, durable and encient to a high degree.

Other objects of this invention will in part be obvious and in part hereinafter pointed out.

The invention, accordingly, consists in the features of construction, combinations of elements, and arrangement of parts which will be exemplied in the construction hereinafter described, and of which the scope of application will be indicated in the appended claims. A

In the accompanying drawing, in which is shown one of the various possible embodiments of this invention.

Fig. 1 is a schematic circuit diagram for a fluorescent electric discharge lamp with the starter switch embodying my invention shown in perspective;

Fig. 2 is Ya sectional view of the switch taken substantially along the line 2-2 in Fig. 1; and Fig. 3 is a top plan view of said switch.

Referring now to .the drawing, I have there y Farms, Massi, assigner New York, N. Y., a cor- (Cl. ZOO-122) shown a fluorescent electric discharge tube I0 of a standard type comprising an elongated pellucid vitreous envelope I2 which is internally coated with a suitable luminescent composition, such as a mixture of phosphors. The tube is lled with a gaseous ionizable medium at a proper pressure, the ends are sealed off. Two spaced i'ilamentary electrodes I4 are enclosed within the tube. These electrodes may be fashioned from or coated with material which will emit electrons when raised to an elevated temperature of or approaching incandescence.

Said tube IIJ is of a type adapted to be used in a xture and with an electric supply and starting circuit requiring the use of a four-terminal starting switch such as the switch I6 which embodies my invention. One of the electrodes I4 is connected to a terminal I8 of a power source, such as an alternating current line, through a lead-in wire 20, in which there is series-connected a standard, manually operated switch 22 and a ballast reactor 24. The other power terminal 26 is connected by a lead-wire 28 to one terminal 38 of my improved starting switch. The diametrically opposite terminal 32 of said switch is connected by a lead-Wire 34 to the other electrode I4 of the discharge lamp. The remaining two diametricallyopposed pair of switch terminals 36, 38 are connected across the other ends of the electrodes I4 by lead- wires 40, 42.

It may be mentioned that the current supply circuit, starting circuit, and starting switch for the lamp, insofar as they have been above described, are conventional and that other standard supply and starting circuits and other starting switches embodying my invention may be employed.

The starting switch of insulating material I6 comprises a base disc 44 from which the terminals 36, 38 project. These terminals, as well as the terminals 30, 32, are adapted to be detachably received in a conventional starting socket (not shown). A tubular shell 46 cooperates with the a to provide an enclosure for the opera- A conductor wire 48 connected to the terminal 3G projects upwardly from the base 44 inside of the shell 45. A similarly disposed conductor wire 5D is connected to the terminal 38. Said two wires have angularly disposed portions 52, 54 received in apertures in a partition 56 of insulating material in such manner as .to support said partition vertically in the shell 46. Any suitable means, such, for example, as a drop of solder (not shown), adhered on the angularly disposed wire portions 52, 54, may be employed to rigidly i'lx the partition. Vertical extensions 58, 60 of the conductor wires 48, 50 on the other Vside of the partition 56 may serve to receive the operative elements of the switch.

In accordance with my invention, said operative elements comprise two contacts 52, S3 which may consist of horizontally arranged electrically conductive heavy metal wire elements which afford large contact areas and are thus capable of opening a great number of times before they become pitted.

In the illustrated form of my invention, the two contacts 52, 53 are closed when the hand switch 22 is open. It will be understood, however, that when my invention is embodied in other types of switches, these contacts may be disposed in spaced relationship when the hand switch is open.

Pursuant to my invention one of the contacts 62 is carried on the free end of a at bimetallic strip A of special but simple configuration. The strip is so fashioned and arranged that, upon energization of a heating means associated therewith, the contacts 62, 63 will open. Said strip includes a vertical leg @li on whose upper end the contact 52 is welded. A second leg 56 is integral with and extends horizontally away from the bottom of the leg 6d. A third leg 53, integral with and angularly disposed relative to the leg B6, is Welded to the upright wire portion 58 to firmly hold the bimetallio strip A in position.

It will be evident as the description proceeds that the third leg 63 of the bimetallic strip A may be omitted and that, in general, said bimetallic strip should be of such shape as to provide two legs which are relatively angularly disposed, one of the legs being supported and the other leg serving to support a contact.

l vAlso in accordance with my invention, suitable heating means, hereinafter described in detail, are arranged in heat transfer relationship with a leg of the bimetallic strip which is disposed in angular relationship to the leg on which the contact 62 is carried.`

By employing this construction I am able to obtain a rapid deiiectionof the free end of the leg SLB of the bimetallic strip A which carries the contact E2, within a shell i6 of limited height. Such result is achieved because the leg lwhen the leg 66 is heated, swings about the bend conrnecting the two legs t@ and t8. Thus the contact 62 swings about a center comprising the supporting point of the leg 56 rather than that of the leg 6d. In the illustrated example this supportingpoint is the bend between the legs Et and 68.'

The other contact et is supported in any suitable manner. For example, it may be welded to the upper end of a vertically `disposed bimetallic strip B whose lower end is secured to the conductor wire portion 6E. A feature of my invention is the provisionof indentation or offset te in the short unbent strip B which points in the direction the strip fiexes upon application of heat and thus serves as an indicating symbol to aid an operator in assembly of a switch. The groove may be formed when the straight strip is cut to length.

Preferably both bimetallic strips are so fashioned and arranged that upon a change in temperature arising from any source other than the heating means, both contacts 62, 63 will move in the same direction. This will com*- pensate for changes in room temperature and heating of the switch by the tube ID.-

Although any suitable heating means may be employed with the bimetallic strip A to effect the foregoing operation, I prefer to employ a heating means which is so constructed that it can be maintained in close and constant heating transfer relationship to the leg 66 of said bimetallic strip. One such heating means comprises a helical resistance wire heating coil 1D encircling and running llongitudinally of said leg 66. One end of the heating coil is welded to a short vertical conductor wire l2 electrically connected to the terminal 32. The other end of the heating coil is connected to a similar conductor wire 'id electrically connected to the terminal 3.` The latter end of the heating wire passes through an aperture 'it in the partition 56. 'Ihe leg 66 is disposed substantially diametrically of vthe heating coil 'E0 and said heating coil is sufficiently large so that when said leg 66 is flexed by heat generated by the coil the strip will not touch the coil.

It will be appreciated that by arranging thecoil li and leg in the foregoing manner, I am able to effect a good heat transfer between said coil and strip which will not be affected by movement of the strip, since as the strip moves away from one segment of the coil, it approaches an opposite segment of the coil.

I It may be mentioned that the switch I6 may be disposed in different positions depending upon the position of the receiving socket therefor. It will, therefore, be apparent that, where in the foregoing description various operative elements have been described as arranged vertically or horizontally, these terms are not limitative. The usual condenser i8 is connected across the terminals 36, 38.

The switch operates in the following manner:

When the hand switch 22 is closed, current flows through va low impedance path, including the ballast reactor 2li, one of the lamp electrodes I4, switch terminal 343, electrode wire 58, bimetallic strip A, contact S2, contact 63, bimetallic strip B, electrode wire 50, switch terminal 38, other lamp electrode lll, switch terminal 32, resistance coil lil, switch terminal 3B, and thence back to the current source. After a short while, which is determined by the time required to heat the electrodes i@ to incandescence and which can be changed by altering the resistance of the coil l0, the heat generated by said coil will cause the bimetallic strip A to flex sufficiently to open the contacts E2, B3. This will break the low impedance series path between the two electrodes I4 and cause surge potential to be applied to said electrodes. If a discharge in the lamp is struck at this time, the lighting current passing through the coil l!) will keep the contacts 62, 63 open. If no discharge is struck, no lighting current will flow through the heating coil, and the coil will, therefore, cool off, permitting the contacts 52, 53 to close after a short time lag. This cycle of actions will be repeated until either the lamp lights or the switch 22 opened.

It will thus be seenV that there is provided a device in which the-several objects of this invention are achieved, and which is well adapted to meet the conditions of practical use.

As various possible embodiments might be made of the above invention, and as various changes might be made in the embodiment above set forth, it is to be understood that all matter herein set forth or shown in the accompanying drawing is to be interpreted as illustrativeandnot in a limiting sense. Y

Having thus described my invention, I claim as new and desire to secure by Letters Patent:

1. A starting switch for an electric discharge lamp comprising a pair of contacts, a bimetallic strip including two straight angularly disposed portions, means to support one of said portions,-

and heating means disposed in heat transfer re lationship with said one portion and open to the atmosphere, one of said contacts being carried by the other of said portions, said heating means including a helical resistance coil enciru cling and running longitudinally of said other portion.

2. A starting switch for an electric discharge lamp comprising a base, a pair oi contacts, an L-shaped flat birnetallic strip one of the legs of which is parallel to and supported from said base, a helical resistance coil of low impedance encircling and running longitudinally of said one leg to repetitvely open and close the contacts for starting the lamp, one of the contacts being carried by the other leg, and a member to support the second contact from said base.

3. A starting switch for an electric discharge lamp comprising a base, a pair of contacts, a

Z-shaped bimetallic strip, the central leg of which is parallel to said base, one of the end legs of said strip being supported from said base, the other end leg of said strip carrying one of the contacts, a helical resistance coil of low impedance encircling and running longitudinally of said central leg to repetiti'vely open and close the contacts for starting the lamp, and a member to support the second contact from said base.

4. A starting switch for an electric discharge lamp comprising a base, a pair of contacts, a flat bmetallic strip including two straight integrally connected, adjacent, angularly disposed portions, one of which lies parallel to said base, means to support said one portion from said base, heating means disposed in heat transfer relationship with said one portion to open and close the contacts for starting the lamp, said heating means comprising a helical resistance coil of low impedance encircling and running longitudinally of the portion of the strip parallel to the base, one of said contacts being carried by the other of said portions, and a member to support the second contact from said base.

FRANK P. GASSER.

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