US2155789A - Resistance shunt - Google Patents

Description

`April 25, 1939.

H. A. GANZ El' AL RES ISTANGE SHUNT Filed June 1, `1937 Patented Apr. 25, 1939 UNITED STATES RESISTANCE sHUN'r Harry A. Ganz and Robert A. Kamm, Hartford, Conn., assignors to Electra Sales Corporation, Hartford, Conn., a corporation of Connecticut Application June 1, 1937, Serial No. 145,875

6 Claims. l(Cl. 200-118) circuit closed through a socket of a lamp when the lamp burns out cr is otherwise damaged and inoperative.

An object of this invention is to provide a simple and inexpensive structure which may be lo disposed in the socket of the lamp Without requiring special construction or dimensions of kthe socket, and wherein the circuit Wires may be secured in the ordinary manner to the inner shell and central contact point of the lamp socket.

15 Another object of the invention is to provide a construction admitting the use of an inexpensive insulating element which may comprise paper` or other suitable material having a shunt perforation therein which is produced in a novel eo and inexpensive manner, such as by depositing a small drop of water on the paper at the desired point for the perforation and subjecting the paper between conductors to the action of a current of lsuflicient potential to arc through the wet 15 spot or portion of the paper and perforate and oxidize the same to provide the shunt aperture of the required size and resistance.

The rinvention also provides a novel construction of outer conductor member which is wiped o or bent into two positions about the insulating element to hold the latter against the outer side of the socket shell by the action of assembling the socket shell within the outer casing or husk of the lamp socket. The construction thus ma- 3 terialiy reduces the number of operations required in the assembling of the parts and maintenance of the parts in the proper relative positions to produce the desired resistance and shunt when the current fails to pass through the lamp t.) socket and the lamp in the usual manner.

With the foregoing and other objects in view, the invention will be more fully described hereinafter, and will be more particularly pointed out in the claims appended hereto.

45 In the drawing, wherein like symbols refer to like or corresponding parts throughout the several views,

Figure l is an enlarged sectional view taken lengthwise through a socket having the shunt :i6 resistance of this invention applied thereto;

Figure 2 is a detail plan view of the resistance element employed;

Figure 3 is a similar View of the outer conductor member for engagement with the resist- 55 ance element;

Figure 4 is an enlarged longitudinal section taken through a modified form of lamp socket constructed according to the present invention and vembodying the novel resistance shunt;

Figure 5 is a det-ail perspective View of the 5 modified form of resistance element shaped in substantially its normal position when assembled in the lamp socket of Figure 4;

Figure 6 is a detail perspective view of the n 'modified form of outer conductor strip prior to 10 mounting and bending into shape yin ythe socket of Figure 4;

Figure '7 is a longitudinal sectional View vthrough another modified form of the invention; and 15 Figure 8 is a detail perspective View of the further modified form of resistance element as applied to the conductor strip.

Referring now to the drawing, I5 designates the casing or husk comprising the outer por- 20 tion of a lamp socket which may be of any suitable fanciful conguration and which has an inwardly extending ledge or shoulder I6 near its upper end. A metallic shell Il is disposed in the casing- I5 and is provided with interior screw 25 threads adapted to receive the threaded ferrule on the base portion of an electric lamp and is adapted to engage the same in electric contact to ground the lamp through the shell I'l. As shown, the shell may comprise a sheet metal 30 body portion flared at its outer end to provide a -ange I8 which may be slitted as shown or other- Wise constructed to snap into position upon the shoulder IB for holding the shell in place. One circuit wire I9 may enter through an opening 20 35 in the bottom of the casing I5 and is secured by solder 2| or the like to the side of the shell Il between the same and the casing, as shown in Figure l.

The bottom of the shell I1 is open and has an 40 inturned flange 22 upon which rests a bottom disc `23 ofl insulating material for closing the lower end of the shell I "I, The shell I1 is beaded or `otherwise suitably formed to embrace the marginal edge portion of the bottom disc 23 for hold- 45 ing it firmly in place. A central bulb contact rivet 24 is secured through the central portion of the bottom disc 23 with the head of the rivet exposed at the upper side of the disc for engaging the central contact of the light bulb when the 50 latter is screwed into the shell I1. Disposed against the lower face of the flange 22 of the shell Il is an insulating or resistance element 25 which may comprise a disc of paper relatively thin and which has a centra-l aperture 26 receiv- 55 ing the lower end portion of the rivet 24 therethrough for centering the disc 25 against the bottom of the shell il. The insulating element 25 is held against the shell by an outer conductor member 2? which also is preferably of disc form and provided with a central aperture 28 for the reception of the lower end of the rivet 24 therethrough, and which is of sufficient inherent stiffness to hold the disc 25 firmly against the bottorn flange 22 of the shell. The rivet 24 is sWaged or expanded over the bottom surface of the conductor member 2 to hold all of the discs 23, 25 and 2l in assembled relation at the bottom of the shell. The rivet 24 preferably has a central depression in its lower end for receiving the exposed extremity of the second wire 29 of the circuit and also to accommodate a blob of solder 35 or the like for securing the wire 29 to the lower end of the rivet.

An important feature of this invention is the preparation and construction of the resistance element 25. When initially formed, the element 25 has deposited at a suitable point upon its surface a small drop of water or the like and the disc is then placed in position in the socket and, before the light bulb is fitted in the socket, a current of suicient potential is passed through the wires i9 and 2S to burn through the wet spot in the disc 25 for perforating the resistance element, as shown at 3| in Figure 2, and for oxidizing the marginal edge portion of the perforation to maintain the same uniform so that the desired resistance, also dependent upon the thickness of the disc 25, is maintained throughout the use of the socket.

In use, when a bulb is inserted in the socket the current passes in the usual manner from the wire 25, rivet 24 to the central contact of the bulb, and from the outer grounded ferrule of the bulb to the shell il' and back to the wire |9.

When the bulb burns out, or otherwise becomes damaged so that current will not flow through it, the potential in the circuit wires 29 and I9 is built up by the resistance of the element 25 sufficiently to pass through the perforation 3 I maintaining the resistance sufficiently to prevent a short-circuiting through the wires 29 and I9. The resistance ol the element 25 is gauged such that it is but slightly greater than the resistance oered by the lamp bulb so that the condition of the circuit through the wires 29 and I9 is maintained with respect to this particular socket. This socket is adapted to be used in a circuit having other sockets therein so that should a lamp in the socket herein disclosed burn out the circuit is maintained to keep the other lamps burning by the passage of the current through the perforation 3| in the resistance 25.

In the modified form of the invention shown in Figures 4, 5 and 6, the resistance element 25 is in the form of a paper cup which may be made from a strip of paper wrapped about the side of the shell l?, as shown in Figure 4, and which has its lower edge portion folded or crumpled upwardly against the bottom of the shell. In this instance the rivet 24 carries a bottom insulating disc 32 against which the paper cup 25 engages. An cuter conductor member 2l of strip form is secured to the lower end of the rivet such as by the solder 39 so that the strip 2'| is in electric contact with the wire 29. The strip 21' is of metal and is also very thin and bendable. The strip 21 initially extends beyond the side of the shell Il so that as the latter is pushed down into the casing l5 the outer end portion of the strip 21 is bent or wiped upwardly about the outer side of the paper resistance cup 25. At any suitable point for registering with the conductor strip 21', the resistance cup 25' is provided with the perforation 3| which is disposed and operates in the same manner as above described in connection with Figure 2.

Referring now to the second modified form shown in Figures 7 and 8, in lieu of the paper cup 25 the conductor strip 21 is provided with a sleeve 252 of paper or the like which comprises the resistance element. This sleeve 252 is of sufficient length to extend considerably across the bottom of the shell and upwardly beyond the free end of the strip 21. The shunt perforation 3|, above described, is provided on the inner sides of the sleeve 252 so as to lie between the strip and shell when the socket is assembled as shown in Figure 7.

The action in both of the modified forms is similar to that of the preferred form of Figures l, 2 and 3 so as to maintain a desired resistance through the socket when the lamp burns out and to also maintain the circuit through the wires connected to the socket from shorting.

The resistance shunt is manufactured by taking a blank of paper, or other suitable material, cut or shaped to the desired size and form for application to the socket and of the necessary thickness to afford the required insulating property. A small drop of water, or other suitable substance, is then deposited on a selected spot on the blank to provide a blank portion of less electricity resistance than the remaining body portion of the blank. The blank is then interposed between conductors in an electrical circuit, such as mounting the blank in the socket as shown in Figures l, 4 and 7, and is subjected to a current of a potential slightly greater than the normal potential circuit of the socket to cause current flow and jump sparking of the current through the wet spot on the blank. This current flow causes the perforation of the wet portion or spot of the blank, as shown at 3|, and the oxidation and carbonizing of the marginal edge portion of the blank defining the perforation. The edge portion of the perforation 3| is therefore hardcned and maintains the size of the perforation 3| so that the resistance to shunting through the perforation remains substantially constant, and the resistance shunt element 25 may be used continuously throughout the life of the socket.

It is obvious that Various changes and modiiicaticns may be made in the details of construction and design of the above specifically described embodiment of this invention without departing from the spirit thereof, such changes and modifications being restricted only by the scope of the following claims.

What is claimed is:

l. A lamp socket, comprising a casing, a lamp receiving shell fitted in the casing, an insulating sheet cupped about the side and bottom of the shell and having a shunt perforation therethrough, a central contact mounted in insulated relation through the bottom of the shell for contact with the central contact of a lamp in the shell, and a contact strip connected to the central contact and extending over the outer side of the insulation sheet and over the perforation therein for maintaining the circuit through the socket closed through said perforation with the desired resistance upon the burning out of the lamp in the shell.

2. A lamp socket having a lamp receiving shell with an insulated contact through the bottom thereof, a contact strip secured to the outer lower end of the contact, an insulating sheet having a shunt perforation therein disposed about the side and bottom of the shell between the latter and the contact strip, and a casing engaging about the shell and the insulating sheet and contact strip to house the same and bind the contact strip against the sheet over the perforation therein and hold the latter to the side of the shell.

3. A lamp socket, comprising a casing, a lamp receiving shell tted in the socket, an insulating bottom in the shell, a central contact carried through the bottom for engaging the central contact of a lamp, an insulating member wrapped about the outer side and bottom of the shell between the same and the casing and having a shunt aperture therethrough, and a conductor strip secured to the central contact of the bottom of the shell and extending against the bottom of the insulating member and upwardly between the side thereof and the casing over said shunt perforation to maintain when the lamp is burned out the circuit closed with a resistance equal substantially to that of the lamp.

4. A lamp socket, comprising a casing, a lamp receiving shell fitted in the casing and having an insulated bottom with a central contact extending therethrough, a bendable strip secured to the outer end of the central contact and extending therefrom across the insulated bottom and upwardly between the side of the shell and the casing, and an insulating sleeve disposed over the strip for insulating the same from the shell and having a shunt perforation through its inner side for closing the circuit upon increased potential between the strip and the shell.

5. A lamp socket having an outer casing, a lamp receiving shell in the casing and having a central insulated contact secured through the bottom thereof, a conductor member connected to the lower end of said central contact and disposed exterior of the shell, and an insulating element having a current shunting perforation therethrough disposed between the shell and the conductor member for shunting the circuit through the lamp socket upon increased potential incident to failure of current in the lamp.

6. A lamp socket comprising a casing, a lamp receiving shell fitting in the casing and having an open bottom with an inturned flange, an insulating bottom seated on the flange, a central contact secured through the bottom, an insulating member fitted against the lower face of the flange, a conductor member secured upon the lower end of the central contactagainst the outer face of the insulating member to hold the latter to the flange, said insulating member having a shunt perforation therethrough for maintaining the circuit closed with the necessary resistance when the lamp burns out.

HARRY A. GANZ. ROBERT A. KAMM.

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