US2584677A - Lamp socket for elongated tubular lamps - Google Patents

Description

Feb. 5, 1952 F. c. DE REAMER LAMP SOCKET FOR ,ELONGATED TUBULAR LAMPS Filed Nov. 2, 1945 Fig.\.

Inventor:

Frank C. De Reamen by M His Attorney.

Patented Feb. 5, 1952 LAMP SOCKET FOR ELONGATED TUBULAR LAMPS Frank C. De Reamer, Bridgeport, Conn., assignor to General Electric Company, a corporation of New York Application November 2, 1945, Serial No. 626,346

8 Claims. (Cl. 173-328) My invention relates to lamp sockets and more particularly to lamp sockets for fluorescent discharge lamps of the type which operate at relatively high voltages.

Certain types of fluorescent discharge lamps now in use, particularly those applicable to commercial installations, operate at relatively high voltages on the order of 600 to 1000 volts. Such voltages are usually obtained from an autotransformer which also acts as a ballast in the lamp operating circuit. Connections from the transformer to the lamp are made through lamp sockets which support opposite ends of the lamp. In such installations, there is danger of shock to a person if the person inadvertently touches the live contacts of the socket unless precautions are taken in designing such sockets to prevent shock hazards. According to my invention, the lamp sockets areso designed and connected into a lamp circuit as to make it impossible for a person to receive a shock from the sockets when the lamp is removed.

Therefore it is an object of my invention to provide a new and improved lamp socket for supporting one end of a discharge lamp in an operating circuit, the socket being constructed and arranged to open the circuit to the primary of the ballast transformer when the lamp is removed in order to prevent shock hazard.

It is another object of my invention to provide a new and improved lamp socket for supporting the other end of the lamp, the two sockets being so arranged that the lamp can be mounted in the sockets in only one way. The arrangement protects a person from shock if the contact at one end of the lamp is grasped when inserting the other end in either of the sockets.

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

In the accompanying drawing, Fig. 1 illustrates a tubular discharge lamp supported at each end in lamp sockets constructed in accordance with my invention; Fig. 2 is a sectional view through the lamp socket mounting the left hand end of the lamp, the view being taken along line 2-2 of Fig. 3; Fig. 3 is an end view, partly in section, of the socket of Fig. 2; Fig. i is a view looking at the base of the socket with partof the cover plate broken away; Fig. 5 is a sectional view through the socket taken along the line 5-5 of Fig. 4; Fig. 6 is a sectional view through the socket supporting the right hand end of the lamp, the view being taken along the line 66 of Fig. 7; Fig. 7 is an end; view of the socket of Fig. 6 with part of the housing cut away; Fig. 8 -=is a view of the base of the socket with part of the cover'plate broket'r away, and Fig. 9 is a schematic view showingthe sockets connected into a lamp operating cir-'v cuit. I

Referring to the drawing, Fig. 1 shows a tubular discharge lamp I, such as a cold cathode: fluorescent lamp, supported at opposite endsinlamp sockets 2 and 3 constructed in accordance: with my invention. The'sockets in turn are supported from a reflecting surface '4 forming. part of a lighting fixture, or the like. As shown. in dotted lines in Fig. 1, cold cathode discharge. lamps of the type used with the sockets are provided with a single contact pin 5 at each end thereof connected to an electrode. The lampsare adapted to start at voltages ranging from 600 to 1000 volts without preheating of the lamp electrodes.

Referring to Fig. 9, I have shown the lamp socket in schematic form connected into a suit able operating circuit for the lamp. The lamp socket 3 is provided with a single contact for engaging one end of the lamp. On'the other hand, the lamp socket 2 is provided with two spaced contacts which are bridged or shortcircuited by the contact pin on the other end of the lamp when the lamp is inserted in the socket. To supply the proper voltage for starting and operating the lamp, an autotransformer 6 is connected into the operating circuit. It also acts as a ballast. When the lamp is insertedv in the socket 2, a circuit is closed from the '110 volt A.-C. supply to the primary of the ballast transformer. Inasmuch as the ballast acts as an autotransformer, a high voltage will appear across the secondary which is applied across the lamp electrodes to start the lamp and maintain it in operation. With a volt AL-C. supply, the voltage applied by the transformer to the lamp may reach 600 volts or more. When the lamp is removed from the sockets, the circuit to the primary of the autotransformer is opened at the socket 2 because the circuit is formed in part by the contact pin on the end of the lamp. 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 arrangement eliminates danger of shock if the lamp contacts are inadvertently touched. H a

Turning now to the construction of the sockets and referring to Figs. 2, 3, and 4, socket 2 comprises a housing I of any suitable molded insulating material. Preferably, 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 Hi to accomo date spaced conducting bars .l.l.. The conducting bars II are formed of relatively heavy sheet metal, such as brass. As shown in Fig. 2, they are bent with a curve I2 of large radius to form an angle. One end of each of the conducting bars is fastened to the base 8 in any suitable manner, as by two drive pins 13. The same ends of the conducting bars are tapped and screw-threaded to carry a terminal screw 14 for making an electrical connection therewith. The screws :downwardly into openings .15 molded in tl'le b'ase. At :the other end, the .bars extend dovmward-ly into the recess l-il"=-and rest againstiabntments 16 extending outwardly from the-sidewalls of the recess. The spring action acquired by :means'nfthe bend 12 in the bar holds fit'ifirmly in engagement with the abutment l6.

Each bar I I "carries .a flexible spring contact member I] fastened "thereto inany suitable manner'ras by spot welding. As shown in Fig. 4, the

spring contact members are formed with curved 4 nection with the lamp contact pin. A spring 32 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 flared edge serving to engage one of the convolutionsof the spring to hold the spring in position. The other end of the spring bears against 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 38 has a considerable amount of movement within the socket housing since the coiled spring 32 may be compressed to a'considerable degree when inserting the lamp. The purpose of this will be more fully described later.

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 housingwhereit rests. in a recess ,35. The other arm extends inwardly in :a direction parallel to the axis of a lamp when the lamp is inserted in the socket .and is secured in any suit- In order to guide the lamp contact .pin into engagement withthe contact members, the front part of the extension 9 is provided witha recess 9 to accommodate the end of the lamp. The wal1;:at thebottom .of the recessis provided with aniopening 2 0 throughw-hich the contact pinof the lamp extendszinto engagement with the contlct -suriaces [8. Thus the. recess Iii serves as a guide when inserting the lamp in the socket. Italso serves to .support one end of the lamp to pneventithelampfrom tailing out of the socket.

when .connecting .the socket .into the lamp operating circuit shown by Fig. 9, the lead wires are .insentedin a groove 2| formed in the base 8 and are bound around the terminal screws l4.

A cover plate 22,.formed of sheet insulating materiahis then placed over the base 8 and protects the electrical connections. It is held in position bya U-shaped spring clip 23, the ends ofwhich .frictionally engage the walls of openlugs 24 inthe base 8. In order to mount the socket on a support, the base is provided with spaced openings-25' for receiving fastening screws.

'I'Iurn'ing 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 is formed 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 havingan opening29 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 openingin an insulatingdisk '30 which carries a contact disk 3| for making an electrical conable manner, as by a.rivet 3.6, to .a base plate 31 which closes the recess in the extension 28. The base plate 31 rests on a ledge 38 formed around the wall of the base and is held in position by drive pins 39. .A terminal screw -40 .is mounted in the conductor bar 34 for making .an electrical connection with the socket.

In order to provide .a guide for the insulating disk 38 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 guide plate is provided with an abutment 42 which rests in an opening 43 in the conductor .bar 34. 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 41 is then assembled in an upright position on the base plate 31 withv the abutment 42 inserted in the opening 43 in the conductor bar 34. 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 thegroove 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! 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 hatred 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 socket and 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 of 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 itself 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. If, on the other 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 shortcircuited 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 con-' structed 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 ininserted 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 suflicient 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.

The embodiment illustrated in Figures 2 to 5, inclusive, is being claimed in the applicant's copending divisional application, Serial No. 231,917, filed June 16, 1951, and assigned to the same assignee as the present application.

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 forming a recess therein, a conducting member set in a groove in one of said walls, a movable contact disk in said recess for engaging the contact pin of a lamp, a single coiled spring disposed between said contact disk and said conducting member to bias the disk into engagement with the lamp pin and to electrically connect said disk and said conducting member, a guide plate of insulating material extending across the recess, one end of said plate being supported on said conducting member and the opposite end resting in a groove in the opposite wall of the recess and means retaining said plate in the recess, an edge surface of said plate forming a guide and support for said movable contact disk.

2. In a lamp socket, a housing of insulating material having walls forming a recess therein open at one end, a base plate of insulating material for closing said recess, a conducting strip fastened to said plate and being provided with terminal means, a portion of said conducting strip being bent at an angle to said plate and extending into said recess, movable contact means in said recess for engaging a lamp contact pin and a single coil spring disposed between said conducting strip and said contact means for biasing the contact means into engagement with the lamp pin and electrically connecting said contact means and said portion of said conducting strip, the axis of said spring being parallel to said base plate.

3. A lamp socket for a lamp'having a contact pin at one end comprising, in combination, a housing of insulating material having side walls forming a recess therein open at one end, one of said side walls being provided with an opening.

therein for receiving the lamp, a base plate of insulating material positioned at the end of said housing for closing said recess, conducting means fastened to said base plate and being provided with terminal means, a portion of said conducting means being formed at an angle to said plate and extending into said recess, movable contact means in said recess adjacent said opening for engaging the lamp contact pin, a coil spring disposed between said contact means and said portion of said conducting means for biasing said contact means into engagement with the lamp pin and electrically connecting said contact means and said portion of said conducting means, the axis of said spring being parallel to said base plate, and a guide plate disposed between said conducting member and said one wall of the housing, an edge of said guide plate forming a guide for said contact means.

4. A lamp holder comprising, a hollow housing closed at its upper end and opened at the bottom and having an opening in the front face thereof adjacent the upper end, an electrical contact assembly loosely positioned in the housing adjacent its upper end and back of the front opening, said contact assembly including a spring-biased contact member normally positioned adjacent the front opening and movable backwardly therefrom, insulating means positioned within the housing beneath the contact assembly in spaced relation to the bottom edge of the housing to hold said assembly in operating position, said insulating means serving as a lower guide for the contact element, and means for detachably securing said insulating means to the housing.

5. A lamp holder for use with double-ended tubular discharge lamps comprising, a hollow housing member closed at the top and open at the bottom and having an opening in the front face thereof to receive the end of the lamp, a contact element movably positioned back of said opening in the upper closed end of the housing, a spring positioned in said end of the housing normally biasing the contact element to a position adjacent said opening, insulating means positioned within the housing beneath the contact element for supporting and guiding said element, a contact terminal mounted on said means having one end extending upwardly into the housing into electrical contact making relation with the contact element, said contact element and said means being removable through the open bottom of the housing member, and

means tov retainsaid insulating :meansin position within the housing.

6. A lamp holder for use with double-ended tubular discharge lamps comprising, a hollow housing member open at thebottom and having an opening in the front face thereof to receive the end of the device, a spring-biased movable contact element positioned in the upper closed end of the housing, insulating means positioned within the housing beneath the contact element, said means serving as a lower guide for the movable contact element, a contact'terminai mounted on said means'ha'ving one end extending upwardly into the housing into engagement with the contact element, said contact element and said means being removable through the open bottom of the housing member, and means to retain said insulating means'inposition.

7. A lampholder for use with double-ended tubular discharge lamps comprising, a hollow housing member open at the bottom and having an opening in the front face thereof to receive the end of the device, a contact assembly including aspring-biased-movable contact member and an insulatingfollower'carrying said-contact member positioned within-the upper end of the housing member opposite theopening in the front face, insulating means detachably mounted'within the housing member-beneath the contact assembly for supporting said contact assembly, said insulating means :having an upper surface serving as a lowerguide for the follower, a contact terminal having one end mounted-in said insulating means and the other endengaging the contact assembly,

8 and locking means'extending through'thehousing into a vportion of said insulating means for retaining it in position. v

8. A lampholder for use with double-ended tubular electric discharge lamps comprising, a hollow housing of insulating material open at the bottom and having a circular opening in the front face thereof adjacent the top, insulating means detachably secured within thehousing with an upper surface in spaced relation with the top of the housing, acontact assembly positioned within the housing above said insulating means, said contact assembly including'a movable insulating disc disposed adjacent the circular opening in the face of the housing, a contact disc carried by the disc and a coil spring'interposed between the back of the housing and contact disc, and an L-shaped terminal member mounted on said insulating means having its 'upper end in engagement with the coil spring and its other end provided with a binding screw.

FRANK C. DE 'REAMER.

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

UNITED STATES PATENTS Number Name Date 2,262,091 Bryant Nov. 11, 1941 2,297,616 Funk sept. 28,1942 2,393,180 Merrill Jan. 15, 1946 2,393,616 De Reamer et a1. -Jan. 29,1946

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