US2570104A

US2570104A - Lamp socket for elongated tubular discharge lamps

Info

Publication number: US2570104A
Application number: US607622A
Authority: US
Inventors: Reamer Frank C De; John M Pistey
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1945-07-28
Filing date: 1945-07-28
Publication date: 1951-10-02
Anticipated expiration: 1968-10-02
Also published as: DE833086C

Description

06in 1951 F. c. DE R EAMER E'TAL 2,570,104

LAMP SOCKET FOR ELONGATED TUBULAR DISCHARGE LAMPS Filed July 28, 1945 2 Sheets-Sheet 1 Inventors: Franfi C. DeReamer, Jchn M. pisteyq by 4% WV weir" Attorneg.

LAMP SOCKET FOR ELONGATED TUBULAR DISCHARGE LAMPS Filed July 28, 1945 Oct. 2, 1 51 F. c. DE REAMER ETAL 2 Sheets-Sheet 2 iii Patented Oct. 2, 1 951 LAMP SOCKET FOR ELONGATED TUBULAR DISCHARGE LAMPS Frank 0. De Reamer, Bridgeport, and John M. Pistey, Fair-field, Conn assignors to General Electric Company, a corporation of New York Application July 28, 1945, Serial No. 607,622

Claims.

Our invention relates to lamp sockets and more particularly to lamp sockets for fluorescent lamps operated at relatively high voltages with cold cathodes.

Certain types of fluorescent lamps about to be placed on the market are designed to be operated at high voltages and are started with cold cathodes as distinguished from the low voltage fluorescent lamp now in use and in which it is customary to preheat the electrodes before starting the lamp. The cathodes. of such lamps are provided with a single contact pin, one being located at each end of the lamp envelope. Lamps of this type are operated at potentials which may reach 600 volts or more. This voltage is usually obtained by means of an autotransformer which acts as a ballast, connections from the transformer being made to lamp sockets which support opposite ends of the lamp. If such installations employ conventional socket designs, there is some danger of shock to a person if a lamp is removed from the socket and the person inadvertently touches the live contacts of the socket. To overcome this hazard, We so design the lamp sockets and utilize them in a circuit as to make it impossible for a person to receive a shock from the lamp sockets when the lamp is removed therefrom.

It is an object of our invention to provide a new and improved lamp socket for use in a lamp operating circuit, the socket being so designed as to open the circuit to the primary of the ballast transformer when the lamp is removed to prevent shock hazard.

It is another object of our invention to provide lamp sockets for opposite ends of a tubular discharge lamp so arranged that the lamp can be inserted in only one way. With our arrangement, a person is protected from shock if the contact at one end of the lamp is grasped in the hand while the other end is being inserted in either one of the sockets. I

It is still another object of our invention to provide a new and improved socket for tubular discharge lamps provided with means for ejecting the lamp from the socket.

It is a further object of our invention to provide a. socket for a tubular discharge lamp which is of rugged construction and which holds 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 our invention; Fig. 2 is a sectional view through the lamp socket mounting the left hand end of the lamp; Fig. 3 is an end view of the socket of Fig. 2; Fig. 4 is a sectional view through the socket mounting the right hand end of the lamp; Fig. 5 is a view of the interior of the socket of Fig. 4; Fig. 6 is a rear view with the socket terminals exposed; Fig. 7 is a sectional view through the socket taken substantially along the line 'l'! of Fig. 4; Fig. 8 is a schematic view showing the sockets connected into a lamp operating circuit; Fig. 9 is a sectional view through a modified form of socket supporting the right hand end of the lamp; Figs. 10 and 11 are views looking at opposite ends of the socket; Fig. 12 is a sectional view of the socket taken substantially along line l2-l2 of Fig. 9, and Fig, 13 shows the modified form of socket connected into an operating circuit for the lamp.

Referring to the drawing, Fig. 1 shows a tubular discharge lamp I, such as a fluorescent lamp, supported at opposite ends in

lamp sockets

2 and 3. The sockets aresupported beneath a reflecting surface 4 which may form a part of a lighting fixture, or the like. In order to easily remove the lamp from the fixture, the socket 3 is provided with an ejector 5 for moving the lamp axially out of the socket. When removed from one socket the lamp may be easily grasped in the hand and removed from the other socket 2. An ejector of this type is particularly useful in those installations in which the fluorescent lamp is used with a close fitting reflector where it is extremely diflicult to grasp it by hand for removal from the fixture.

Referring to Fig. 8, the lamp sockets are illustrated in schematic form and are shown connected into the operating circuit for the lamp. The lamp socket 2 is provided with a single contact for engaging the contact pin on one end of the lamp I; the socket 3 is provided with two spaced contacts which are bridged by the contact pin on the other end of the lamp so that a circuit is closed between themwhen the lamp is inserted in the socket. In order to supply the proper voltage for starting and operating the lamp, an autotransformer B is connected into the operating circuit. It acts as a ballast. When the lamp is inserted in the socket 3, a circuit is closed from the volt A.-C. supply to the primary of the ballast transformer. Since the ballast acts as an autotransformer, the high voltage appearing across the secondary is applied across the lamp cathodes to start the lamp and to maintain it in operation. With a 110 volt A.-C. supply, the voltage across the secondary of the ballast transformer may reach 600 volts or more. It will be apparent from the circuit of Fig. 8, that when the lamp is removed from the sockets, the circuit to the primary of the transformer is opened at the socket 3. This occurs because the contacts of this socket are short-circuited by the lamp contact pin. Hence, when the lamp is removed from the sockets, the primary of the transformer is deenergized and there is no danger of the high voltage of the secondary being applied to the socket 2. This eliminates danger of shock.

Turning now to the construction of the sockets and referring to Fig. 2, the lamp socket 2 comprises a tubular housing 1 of any suitable molded insulation material. One end of the housing is provided with an opening 8 for receiving the end of the lamp which is provided with a ferrule 9. An insulating plate or disk I is slidably mounted Within the housing and is biased by a Spring II outwardly into engagement with the lamp. An abutting flange I2 adjacent the opening 8 limits outward movement of the disk. The disk carries a metallic contact button |3 which is seated in a recess I4 in the disk and which is held in position by the biasing spring II. In this way, the spring I I makes an electrical connection with the contact button I3. The disk I0 is provided with an opening |5 for receiving the contact pin |li carried by the ferrule at the end of the lamp.

When the lamp is seated in position on the lamp socket, the contact pin on the end of the lamp extends through the opening I5 in the disk I0 into engagement with the contact button I3. In order to provide terminal means for the socket, the opposite end of the spring engages a terminal plate I1. As shown in Fig. 3, the terminal plate I1 is seated in grooves I8 in opposite side walls of the housing 1. It is held in position against movement by means of the insulating tube I9 which extends across the shell. The terminal member I1 is held in position against the tube by action of the spring II.

A screw 20 extends through the insulating tube I9 and is used to mount the socket on any suitable support such as a U-shaped strap 2|. As shown in Fig. 1, this U-shaped strap is mounted on the reflecting surface 4. In actual use, the U-shaped strap would be mounted on the fixture channel and the reflector would be cut out at either end to surround the strap. The plate I1 is provided with a terminal screw 22. When a conducting wire is fastened to the screw 22, the wire is so arranged as to rest in a recess 23 formed in the upper side wall of the housing. This permits the rear end of the socket to be completely protected by a cover plate 24. The plate is formed of sheet insulating material and is pivoted to the socket by means of a drive pin 25. When making an electrical connection, the cover plate is ro tated to expose the terminal screw 22. After the connection is made, the cover plate is snapped back over the exposed terminal plate I1 where it is held in position by a lug 26 adapted to be seated in a corresponding recess 21 formed in the cover plate 24.

The socket is one which may be easily manufactured at low cost. Inmanufacture, the disk I0 and contact button I3 are assembled together and placed in the housing. Then the sprin II is inserted and the terminal plate seated in the grooves l8. The insulating sleeve I9 is installed to hold the parts in assembled position.

The socket supports one end of the lamp firmly and securely. The spring II serves to bias the lamp into engagement with the socket at the opposite end. As shown in Fig. 2, the housing 1 is elongated to provide for a substantial amount of movement of the disk In so that the lamp may be inserted into the socket for a considerable distance before the other end of the lamp is clear of the other socket 3 for insertion therein. The reason for this construction will be described later.

Turning now to the construction of the right hand socket and referring to Fig. 4, the socket 3 comprises a base 28 of insulating material, such as a molded plastic, the base bein provided with a recess 29 for receiving the lamp ferrule and contact pin. As shown by Fig. 7, the bottom wall of the recess carries two spaced contact means in the form of hollow rivets 30, each being provided with a terminal screw 3| and each having a contact member 32 secured thereto. The contact members are fastened to the hollow rivets by any suitable means, such as spot welding. The contact members 32 are bent in the form of a U to provide flexible contact blades 33 which extend inwardly from the walls of the recess toward each other and which are spaced apart a distance slightly less than the thickness of the lamp contact pin I6. When the lamp is mounted on the socket, the lamp contact pin I6 engages each one of the contact blades 33 and electrically short circuits the contacts. At the same time the socket contacts make an electrical connection with the lamp contact pin.

In order to insulate the contact members and prevent them from being completely exposed in the open end of the recess 29, a plate 34 of insulating material is placed in the recess and overlies the spring contact members in the manner shown by Figs. 5 and 7. The plate rests on abutments 35 extending inwardly from the wall of the recess. It is held in position by drive pins 36. So that the lamp contact pin may engage the socket contact members, the plate 34 is provided with an opening 31 of a size to receive the lamp contact pin. The plate is also provided with a slot 38 extending from the opening 34 to the outer wall of the recess 29 which provides a space for movement of the ejector 5 in a manner to be described later.

As shown in Fig. 6, the terminal screws 3| are set in recesses 39 in the rear wall ofthe base and they are separated from each other by an upstanding boss 40. The rear wall of the base is provided with spaced grooves 4| for receiving conductors to be connected to the terminal screws 3|. The terminal screws and the electrical connections to the socket are protected by a pivoted cover plate 42 mounted on the base by means of a drive pin 43. Fig. 6 shows the cover plate rotated away from the base to expose the terminal screws for making an electrical connection with the socket. The cover plate is formed of flexible insulating material, such as sheet fiber, and it is held in position protecting the terminal screws 3| by means of a lug 44 on the housing which engages a corresponding slot 45 formed in the edge of the cover plate. A screw 46 extends through the base and serves to fasten it to one of the U- shaped strap members 2| which in turn is mounted on the reflecting surface 4.

The ejector 5 comprises a lever 41 which is formed of insulating material and which is mounted by a pivot 48 on a U-shaped bracket 49. The bracket is fastened to the base by means of the aforementioned screw 45. One end of the lever extends outside the housing to form a handle. The other end extends within the housing and is provided with a curved surface 50 for engaging the lamp contact pin. This surface itself is provided with a groove 5| which tends to grip the lamp contact pin and prevent it from slipping sideways when the lever is moved to force the lamp contact pin out of the socket.

When the lamp is in seated position on the socket, as shown in Figs. 4 and 7, the inner end of the lever 41 rests against the bottom wall of the recess immediately in back of the lamp contact pin. When it is desired to eject the lamp from the socket, the handle of the lever is moved toward the back of the socket, as shown in the dotted line position of Fig. 4. This causes the opposite end of the lever to move forwardly into the space between the contact blades 33 and through the slot 38 in the protecting plate 34 to forcibly move the lamp and the lamp contact pin out of the socket. The curvature of the inner face 50 of the ejecting lever is such as to move the lamp contact pin outwazdly and downwardly to eject the lamp from the socket into a position such as indicated in dotted line by Fig. 1. During ejection of the lamp, the lamp is moved against the action of the spring I I in the opposite socket 2.

Referring to Fig. 8 in which the

sockets

2 and 3 are shown in schematic form, it will be zipp rcut that the circuit to the primary of the ballast transformer is open at all times unless the lamp is mounted in position in the socket 3. When mounted in the socket, the lamp contact pin bridges the space between the contact members of the socket to close the circuit to the primary. As long as the lamp is out of the circuit, there is no possibility of high voltages being applied to the single contact of socket 2. Thus, if the contact member of the socket 2 is inadvertently touched, no shock can be obtained from it. For the same reason, if one end of the lamp is inserted in the socket 2 and the other end gripped in the hand, a shock cannot be obtained through the lamp because the socket 2 is dead. On the other hand, if the user comes in contact with the live contacts in socket 3, no harm will result because this socket is connected to the low voltage side of the ballast transformer. Moreover, the contacts are normally open circuited. Even if the contacts are short-circuited by inserting one end of the lamp in the socket 3 and the-other end of the lamp grasped in the hand, still a shock cannot be obtained through the lamp because the socket 3 is connected into the low voltage primary of the transformer.

It will be apparent that the

sockets

2 and 3 are constructed and mounted so that the lamp can b inserted only in one way. The arrangement is such that the lamp must first be inserted in the high voltage or secondary socket 2 and then inserted in the low voltage socket 3. If one end of the lamp is inserted in the socket 3, the other end can not be inserted in socket 2 because the contacts in the socket 3 are not movable and the end of the lamp will simply rest against the plate 34 or the ejector lever 41. The spacing between the edges of the sockets is less than the length oi the lamp so that it is impossible to insert the other end of the lamp in socket 2. On the other hand, when one end of the lamp is first inserted in the socket 2, the end of the lamp may be inserted a considerable distance into the socket due to the movement of the disk III in the elongated housing 1 against the action of the spring II. By this arrangement, the lamp may be inserted in the socket 2 a sufficient distance so that the other the lamp. For example, in the corner of a show 7 end of the lever by a pin 54.

case the lamp is mounted so close to the walls that it is troublesome to grasp the lamp and move it longitudinally for removal from the sockets. In such instances, the ejector greatly facilitates removal of the lamp because it not only removes the lamp from the one socket but also guides the lamp away from the socket to a position such that it may be easily grasped in the hand for removal from the socket 2.

The modified form oi? socket shown by Figs. 9, 10, 11, and i2 is similar to that shown by Fig. 4 except that a slightly different arrangement of the socket contact members and ejector is provided for. With the exception of these parts, the various elements of the socket are the same and have been identified with the same numerals used to identify the parts of the socket of Fig. 4.

Referring to Fig. 12, it will be seen that the hollow rivets 30 are mounted in the bottom wall of the recess 29 and are provided with terminal screws 3|. However, instead of being provided v ith the spaced flexible contact members 32, one of the rivets carries a flexible spring blade or arm 52. The spring arm 52 is fastened to the hollow rivet inany suitable manner, as by spot welding, and extends across the bottom of the recess to a position such that it may be moved into engagement with the other rivet to shortcircuit the socket contacts. In order to make an electrical connection with the lamp contact pin, the ejector lever 41 is provided with a conducting tip 53 which is adapted to engage the lamp contact pin. This tip is fastened to the When the lamp is seated in position on the socket, the lamp contact pin l6 engages the conducting tip 53 and forces it backward against the flexible spring blade 52 to short-circuit the contacts. This position of the elements is shown by Fig. 9. The conducting tip is provided with a curved surface 55 which provides a good contacting surface for the lamp contact pin and which serves to guide the contact pin when ejecting the lamp from the socket in the manner already described.

Fig. 13 shows the modified form of socket connected into a lamp operating circuit. When a lamp is inserted in socket 3, the conducting end of the ejector engages the spring blade 52 to move into engagement with the rivet 3 0. This short-circuits the socket contacts and closes the circuit to the primary of the ballast so that a high voltage appears at the secondary to start and operate the lamp.

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

1. In a lamp holder for an elongated tubular lamp having a single contact pin at each end comprising a pair of spaced sockets, the first of said sockets having spring biased means adapted to exert axial pressure against a lamp inserted in the socket to urge the opposite end of the lamp into the second socket, the improvement comprising ejector means in said second socket including a lever pivoted on said second socket and having an arm extending into the interior thereof and a second arm extending outside thereof adapted to be manually operated for urging a lamp, out of said second socket and farther into the first socket against the action of said spring means. i

2. In a lamp holder for an elongated tubular lamp having a single contact pin at each end comprising a pair of spaced spckets, the first of said sockets having spring biased means adapted to exert axial pressure against a lamp inserted in the socket to urge the opposite end of the lamp into the second socket, the improvement comprising ejector means in said second socket including a lever pivoted on said second socket and having an arm extending into the interior thereof and a second arm extending outside thereof adapted to be manually operated for urging a lamp out of said second socket and farther into the first socket against the action of said spring means, a pair of normally open-circuited contact means disposed within said second socket and positioned so as to be interconnected with a lamp pin under the pressure exerted thereby by reason of the influence of the spring bias in said first socket, said interior arm of said lever being positioned between said contact means to act directly against the lamp contact pin.

-3. A lamp socket for a lamp having a contact pin at one end comprising, in combination, a base of insulating material having a recess therein. contact members mounted in said recess, said contact members extending toward each other but with a space therebetween whereby they may be engaged by a lamp contact pin to close an electrical circuit between them, a protecting plate of insulating material overlying said contact members and having an opening therein for receiving the lamp contact pin, and a lever pivoted on said base and having a portion within said recess adapted to engage the lamp contact pin, said portion being movable through the space between the contact members and the opening in said plate to eject the lamp from the socket.

4. A lamp socket for an elongated tubular lamp having at one end a single axially projecting contact pin comprising a housing having a recess therein, an apertured wall of insulating material partially closing said recess and disposed in a fixed position with respect to said housing, said wall aperture being adapted to receive a lamp contact pin whereby said pin may be extended into the recess in back of said wall, a pair of individual permanently spaced contact blades, means for securing the same in said housing recess in back of said wall, each contact blade extending from its securing means towards said wall aperture to have a yieldingly spring-tensioned contact end portion positioned wholly within said housing and in proximity to said wall aperture, the contact end portions of both of said blades being positioned in a common plane perpendicular to the axis of said wall aperture, and said contact end portions lying within the projectionof said wall aperture on said plane whereby said lamp contact pin when inserted in said aperture is yieldingly contacted by both of said contact blades thereby interconnecting said blades and the lamp contact pin for completing circuit connections therethrough.

5. A lamp socket for an elongated tubular lamp having at one end a single axially projecting contact pin comprising a housing having a recess therein, an apertured wall of insulating material partially closing said recess and disposed in a fixed position with respect to said housing, said wall aperture being adapted to receive a lamp contact pin whereby said pin may be extended into the recess in back of said wall, a pair of individual permanently spaced contact blades, means for securing the same in said housing re-. cess in back of said wall, each contact blade extending from its securing'means towards said wall aperture to have a yieldingly springtensioned contact end portion positioned wholly within said housing and in proximity to said wall aperture, one of said blades having its contact end portion positioned in a plane perpendicular to the axis of said wall aperture with the contact end portion of each of said blades lying within the projection of said wall aperture on said plane whereby said lamp contact pin when inserted into said aperture is yieldingly contacted by both of said contact blades thereby interconnecting, said blades and the lamp contact pin for completing circuit connections therethrough, said blade securing means comprising a second wall forming a part of said housing and having a pair of apertures receiving a portion of said contact blades, screw means positioned on the 0pposite side of said second wall from said contact blades engaging each of said contact blade portions extending through said apertures to provide terminals for making circuit connections to said blades.

FRANK C. DE REAMER.

JOHN M. PISTEY.

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

UNITED STATES PATENTS Number Name Date 646,179 Irland Mar. 27, 1900 2,109,341 Rebl Feb. 22, 1938 2,259,378 Heidkamper Oct. 14, 1941 2,307,423 Savage Jan. 5, 1943 2,393,180 Merrill Jan. 15, 1946 2,415,496 Ingwersen Feb. 11, 1947 2,427,225 Mueller Sept. 9, 1947 2,464,643 Kulka Mar. 15, 1949 FOREIGN PATENTS Number Country Date 19,045 Great Britain of 1909 445,486 Great Britain Apr. 14, 1936 480,774 Germany Aug. 9, 1929 684,289 Germany Nov. 25, 1939