US2604505A - Lamp socket for elongated tubular fluorescent discharge lamps - Google Patents

Description

f July 22, 1952 F. c. DE REAMER 2,604,505

LAMP SOCKET FOR ELONGATED TUBULAR FLUORESCENT DISCHARGE LAMPS Original Filed Nov. 2, 1945 Inventor: Frank C Patented July 22,;1952

- jmtttisoesm [FLUORESCENT DISCHARGE LAMPS 1 Frank C. De Reamer, Bridgeport, Con'nsassig'nor ew York 1 toiGeneral Electric Company, a corpm'ation of M ijr'i inai applicatiofi'Novemtel-"z, 1945;seri'a1'No.

626,346. Divided and thisapplicatioli June 16; e '1951,*St":ri al'No. 231,917 7 T r This is a divisionaof my copendingapplication :Serial. "No. 626,346, filed November. 2, ..1945,x or Lamp Sockets which; has. matured into- United States :Patent No..2.5l8.4,677, issuedFebruary 5, 1952; 1 I, Myinvention relatesito lampso'ckets and :more particularly to .lamp sockets for fluorescent discharge lamps .of thetype which operate at relatively-high voltages. v r

Certain types of fluorescent discharge lamps now in use, particularly those, applicable ,to commercial installations, operate, at relatively high ,voltages on the order 0360,0110 1000 volts. Such voltages are usually obtai-nedjrom an au-totrans- :former'which a-lsoacts as a ballast in 711612111113 operating circuit. Connections irom' the transformer to the-lamp are, made through lamp o t -w h u p tc pesite e s. of helamp- In such installations, thereis dangerot shock to a e se i t e ninadv n t uch s h J o t t of t e 'eeek ti nles ee u ie e taken in designing such sockets to prevent shock hazards e e di sjte .m v ti l t lamp sockets are so designed and connected into a lamp 1 @r raibeste r ek it kn 9s i e e a person to vreceive a shock from the sockets when the lamp s em ea 1; .e ei r ziti e. an b t or m ve o to provide a "new and improved lamp socket for lsupporting one end of a discharge lamp in an ,p'perating circuit, the socket beingconstructed .and" arranged to open the circuit to the primary 50 the ballast transformer when the lamp is Tfeiriov'ed in order to prevent shock hazardj 'It'ig anotherobjec't'loi my invention to provide ,anew and improved lamp socket for supporting the other end of the lamp, the two sockets being so arrang'd'tha-t the lamp can be mounted in the sockets in onlyone way. "Ih'e arrangement protects aperson" from 's'ho'ck"if the contact atone Qci'ld of the lamp grasped when inserting the 'oth'ereiid' in either or the sockets.

It is' 'a further objeet of my invention to provide sockets for a tubular lamp which are of simpleconstruction, easily manufactured at low cost, Thesocketsare so designed as to hold the .lamp securely in position at all times.

' In -the aocornpanying drawing, Fig.1 illustrates a tubular discharge lam'p supported at each end lamp sockets constructed in accordance with my invention; Fig. 2 is a sectional view through ithe l'ampsocket mounting the left hand end of Lthe lamp, the viewbeing taken along line 2- -2 -qiFig-B; Fig. .3' is an end view, ;partly in section, of the socket of Fig. 2; Fig. 4 is a view looking "2f seals. (01. 173-323 at the bas of thesecket with part o th cover plat broken away: F oisa s tional vi w hrou h the socket. taken alon t e line '55.of i -L 5 F g. 6. is asectionalviewth ous th socket supporting the right .-hand end 01 ;the lamp, the viewbeingtaken along the line B fi of Fig. 7; Fig. 7 is an end view oftihe .SQcket of F 6 with part of t hous g cut aw .Fis- 8 is a view of the base of the socket with part of t e e P e. b ke ewah nd. Fis- 9 a schematic view showing the sockets connected into a lamp operating circuit. 7 v I Referring tothe-drawing, Fig. 1 shows .a tubular discharge lamp SllCh as a cold cathode fluorescent lamp,, suppor,ted atopposi-te ends in lamp sockets 2 and 3 constructed in accordance with my invention. The sockets in turn-are supported from a reheating surfaced :forming part of a lighting fixture, or the like. As shown in dotted lines in Fig. 1, cold cathode discharge lamps of the ype used'with the. sockets are provided with a single contact lamest each'end thereof con-' nected to an eleetrode, The lamps are adapted to start at voltages ranging frorri 600 to 1000 volts without preheatingof thela'mpleleetrodes.

Referring to Fig. ,I'have shown the lamp socket-in schemati term cjnneted into a suitable operating circuit for the lalhp. The lamp socket .3 is providedwith a single contact for engaging one end of the lamp. Qnfthe other hand, the lamp" socket .2 is provided with two spaced contacts which are Bridged or? short-circuited by thecointact pin on the ipther' end of the lamp whrithe lamp'is inserted in the socket.

TO supply the proper voltagefor starting and operating the lamp, an autotran'sformer 6' is con-, nected into the voperatingcircuit. It also acts as a ballast. When the jlamp is inserted in the socket 2, a circuit is closed from thellO Volt A.-C supply to the primary ,of the ballast transformer. Inasmuch as the ballast acts as an autotransformer, a high" voltage willappear across the secondarywhichis applied across .the lamp electrodes .tostart' the. lamp and maintain it in operation. With a 11.01 volt A.-,C.- supply. the voltage applied by the transformer to the lampr'nay reach .600' tons or more. When .the

lamp'is ,removed'iromthe -.so'ckets,-the circuit to the primary of the lautotrans'f ormer is opened :at

.the socket 2' because the circuit is tor-med in part by the contact pin on the endcf the-lamp, I Thus when the lamp is removed from the sockets, the primary of the transformer is deenergized and consequently there is no danger of secondary high voltage being applied to the socket 3. This arrecess.

contacts are inadvertently touched.

Turning now to the construction of the sockets and referring to Figs. 2, 3, and 4, socket 2 comprises a housing 1 of any suitable molded insulatingmateriaL wPreferably, the housing is molded in a'single piece. It is formed with a base portion 8 for mounting the socket on a support and an extension 9 for supporting the lamp. During the molding operation, the ,extension is formed with a recess in to accommodate spaced conducting bars II. The conducting bars H are formed of relatively heavy sheet metal, such as brass. As shown in Fig. 2, they are bent with a curve ['2 of large radius to form an angle. One end of each of the conductingbars is fastened to the base 8 in any suitable manner, as by two disk 3'! for making an electrical connection with the lamp contact pin. A spring 3'2 biases the contact disk into engagement with the lamp contact pin. One end of the spring rests against the flared edge of an opening 33 in a conductor bar ;34, the-flarededge servingto 'engage. one of the convolutions of the spring"tohold the spring in drive pins l'3. The same ends of the conducting bars are tapped and screw-threaded to carry a terminal screw M for making an electrical connection therewith, The screws extend downw'ardlyinto openings [5 molded inthe base. 'At the'other end, the-bars. extend downwardly into the-recess I0 and rest against abutments I6 extending outwardly from the side Wallsoi' the The-spring action acquired by means of the bend l2 in the bar holds it firmly in engagementwith the abutment I'B. a v -'Each bar H carries a-flexible spring contact -member I! fastened thereto in any suitable man- ;ner as by spot welding. As shown in Fig. 4, the --"spring contact members are formed with curved portions extending toward each other to provide contact surfaces l8 for engaging the contact pin Son the end of the lamp. The contact surfaces are normally spaced from each other maintainiing-the circuit open, unless the lamp is inserted i'nthe socket so that the lamp contact pin engages and brid es the contact surfaces. "In-order to guide the lamp contact pin into engagement with the contact members, the front part of the extension}! is provided with a recess 19 to accommodate the end of the lamp. The wall at the bottom of the recess is provided with an opening 201throughwhich the contact pin of the lamp extendsinto engagement'with the contact-surfaces" l8. 'Thus the recess 19 serves as a :guidewhen inserting the lamp in the socket. I also-serves to support one end of the lamp to prevent the lamp from falling out of the socket.

When connectin the socket into the lamp op- -crating circuit shown by Fig. 9,'the lead wires areinserted ina groove 2| formed in the base 8 jand'are' bound around the terminal screws [4. A pover plate 22, formed of sheet insulating material, is then placed over the base 8 and protects the electrical connections. It is held in position @by a U-shaped spring clip 23, the ends of which ifrictionally engage the walls of openings '24 in the base 8. In order to mount the socket on a support, the base is provided with spaced open- 'ings'25 for receiving fastening screws. 1

Turning now to the construction of the right hand socket and referring particularly to Figs. 6, 7, and 8, the socket 3 comprises a housing 26 of any suitable insulating material molded in a single piece. It isformed with a base portion 21 for securing the socket to a support and an extension 28 for supporting the lamp. As shown in Fig. 6, the extension is provided with a recess having an opening 29 in one side wall thereof for receiving the end of the lamp when the lamp is mounted in the socket. The contact pin on the end of the lamp is adapted'to rest in an opening in an insulating disk 30 which carries a contact "conductor bar 34.

the contact disk 3|. In this Way an electrical connection is obtained between the contact disk and the conductor bar. It will be apparent that the insulating disk 30 has a considerable amount of movement within the socket housing since the coiled spring 32 may be compressed to aconsiderable degree when inserting the lamp. The purpose or this will be more fully described later. 1-

The conductor bar 34 comprises a strip of sheet metal such as brass. It is bent to form an angle.

One arm of the angle containing the opening 33 extends along the opposite side wall of the housing where it rests in a recess 35. The other arm extends inwardly in a direction parallel to 'theaxis of a lamp when the lamp is inserted in tion with the socket. V

In order to provide a'guide for the insulatin disk 30 and to maintain it'and the spring 32 in 'position, a guide plate 4| is mounted on edge within the extension. One edge of the uide plate is provided withan abutment 42 which rests in,

an opening 43 in the conductor bar 3 4. The opposite edge is provided with a similar abutment 44 which rests in a groove 45 formed in the wall of'the housing 26. Preferably the guide plate is formed of any suitable insulating material such as sheet fiber.

' In assembling the socket the coiled spring 32, the insulating disk 30 and the contact disk 3! are first inserted in the'recess in the housing extension 28. The guide plate 4| is then assembled in an upright position on the base plate 3'! with the abutment 42 inserted in the opening 43 in the This assembly is then fitted down into the housing with the conductor bar 34 resting in the groove 35 on one wall of the housing and the abutment 44 of the. guide plate resting in the groove 45 on the opposite wall of the housing. The base plate 31 is then fastened to. the housing by the drive. pins 39 in the manner already mentioned. As shown in Fig. 6, when in assembled position, guide plate 4 1 forms a guide and support so that the insulating disk 30 may 'slide back and forth along its inner edge 46.

.When making an electrical connection with the socket, the insulated conductor is laid in a groove 41 formed in the base and the bared end is bent around the terminal screw 40;. A cover plate 48 of sheet insulating material is then placed on the base to enclose the socketand provide protection for the electrical connection. It is held in position by means of a U-shaped spring clip 49 which cooperates'with openings. in the base in the same manner as the spring'clip 23 01' socket 2.

Referring to Fig. 9 in which the sockets 2 and 3 are shown in diagrammatic form, it will be seen that the circuit to the primary of the transformer is open at all times .unless the lamp is mounted in position in the socket 2 so that the lamp contact pin short-circuits the normally open contacts of the socket. As long as the lamp is removed from the socket, there is no possibility of high voltages being applied to the single contact of socket 3. Thus if the contact disk 3| of socket 3 is touched inadvertently, no shock can be obtained from it. Similarly, if the lamp itseli. is inserted in socket 3 and the other end of the lamp gripped in the hand, a shock cannot be obtained through the lamp itself because the socket 3 is dead. It, on theother hand, the user accidentally touches the live contacts in socket 2, no appreciable harm will result because this socket is connected to the low voltage side of the ballast transformer at 110 volts A.-C. In some instances, the contacts may be short-circuited by inserting one end of the lamp in socket 2 and grasping the other end in the hand. Still a shock cannot be obtained through the lamp in such a situation because the socket 2 is connected into the low voltage side of the circuit.

With further reference to Figs. 2, 6, and 9, it will be seen that the sockets 2 and 3 are constructed and mounted so that the lamp can be inserted in one way only. The arrangement is such that the lamp must first be inserted in the high voltage or secondary socket 3 and then inserted in the low voltage socket 2. If one end of the lamp is first inserted in the socket 2, the other end cannot be inserted in socket 3 because the end of the lamp will rest against the fixed.

bottom wall of the recess 29. The spacing of the edges of the sockets is, less than the length of the lamp so that it will be impossible to insert the other end of the lamp in socket 3. However, when one end of the lamp is first "inserted in socket 3, this end of the lamp may be inserted a considerable distance into the socket due to the large amount of movement provided by the coiled spring 32. This means that the lamp may be inserted a distance sutficient so that the other end of the lamp 'clears the edge of the socket 2 into which it. is snapped by the pressure of the spring 32 in the socket 3. Thus the circuit to the primary of the transformer is completed to energize the lamp operating circuit only after the lamp is fully mounted on the lamp fixture first by inserting it in socket 3 and then mounting it in socket 2.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In a lamp socket, a housing of insulating material having walls therein forming a recess having one open end, one of said walls being provided with an opening having a diameter suitable for receiving an axially inserted lamp contact pin, spaced abutments within said housing extending from said walls adjacent said opening, spaced conducting members, one end of each resting against a corresponding abutment, and conducting member being fastened to said housing, the other end extending into said recess and resting against a corresponding abutment, and spaced apart flexible contact fingers carried one by each of said conducting members to be dis posed behind said opening for making an electrlcal connection with a lamp pin.

2. In a lamp socket, a housing of insulating material having walls forming therein a recess having one open end, one of said walls being provided with an opening having a diameter suit-.- able for receiving an axially inserted lamp contact pin, spaced abutments extending from said walls adjacent said opening, spaced apart contact strips carried by said housing, one end of each strip being fastened to said housing and being provided with terminal means, the other end of each strip being disposed at an angle and extending into said recess to rest against a corresponding abutment, and a flexible spring contact finger carried by each of said said contact strips and being disposed behind said opening for making an electrical connection with a lamp pin.

FRANK C. DE REAMER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Levenson Nov. 14, 1950

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