US2716224A - Lamp sockets for single pin fluorescent lamps - Google Patents

Description

Aug. 23, 1955 M. H. KRUG ER LAMP SOCKETS FOR SINGLE PIN FLUORESCENT LAMPS Filed April 9, 1952 TEEN;

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1 lNVENTOR MICHHEL HENRY KRUGER (A: ATTORNEY United States Patent LAMP SOCKETS FDR SINGLE PIN FLUORESCENT LAMPS Michael Henry Kruger, Maiden, Mass., assignor to A. L. Smith Iron Company, Chelsea, Mass., a corporation of Massachusetts Application April 9, 1952, Serial No. 281,315

Claims. (Cl. 339 -55) This invention relates to sockets for fluorescent lamps in general and more particularly to lamp sockets for single pin fluorescent lamps.

With fluorescent lamps, and particularly with single pin fluorescent lamps where a low voltage circuit and a high voltage circuit are both required to be established,

in the interest of safety, various contrivances have been devised to insure that one circuit is not closed before the other circuit is closed, and similarly that when removing a lamp, both circuits will be interrupted simultaneously. To this end a fixed sleeve and a fixed seat have been provided for one pin and a yieldable seat for the other pin, the contact associated with the pin for the yieldable seat not completing a circuit until contact associated with the pin for the fixed seat is in contact, the pin associated with the fixed seat being barred from contact until after the pin associated with the yieldable seat has been positioned. With these contrivances, however, difliculty has been encountered in effecting a positive contact with the pin associated with the yieldable seat.

With the foregoing in mind, the present invention aims to provide a socket having a yieldable seat which will insure a positive contact with the pin associated with the yieldable seat when the pin associated with the fixed seat is brought into contact and to maintain such positive contact throughout the illumination of the lamp.

In practice, the authorities, such as the Underwriters Laboratory, have required with the conventionally fixed socket and yieldable socket between which a fluorescent lamp is positioned, that the contact disk of the yieldable socket be spaced not less than a predetermined distance, conventionally one-quarter of an inch from the outer face or outer seat of the yieldable socket to the contact disk. This requirement has created problems. As an instance, since the outer free end of the head of the contact pin of a fluorescent lamp is conventionally spherical, it has been considered good practice to adopt a length of five-sixteenths of an inch for the same extending from the outer free end of the head of the contact pin to the outer face of the cap of the lamp, thus allowing onesixteenth of an inch tolerance for the pin to find its final seat on the contact. Normally, this one-sixteenth of an inch tolerance would permit the desired positive contact between the pin head and the contact disk in the yieldable.

socket. However, because of the difiiculty, from a manufacturing standpoint, to produce uniform spherical forms for the free ends of the contact pins, because of the difiiculty from a manufacturing standpoint to produce uniformly formed round holes for the contact disks constituting the seats for the contact pins, and because of other variations from a manufacturing standpoint, this one-sixteenth of an inch tolerance does not always result in a positive contact, and consequently objectionable arcing and accompanying burning of associated parts is encountered.

According to the present invention a weaker spring is provided mainly to maintain the contact disk the required 2,7 16,224 Patented Aug. 23, 1955 further compression necessary securely to accommodate.

a fluorescent lamp between the yieldable socket and the fixed socket. Consequently, when the contact pin of a fluorescent lamp is inserted into the yieldable socket,

(l) The initial pressure placed upon the yieldable socket is taken up by the weaker spring to insure a positive contact between the outer free end of the contact pin and the seat of the contact disk,

(2) The ultimate compression securely to accommodate the fluorescent lamp between the yieldable socket and the fixed socket is taken up by the stronger spring,

(3) In inoperative position, that is when not supporting a lamp, the one-quarter of an inch space between the contact disk and the outer face of the yieldable contact is maintained, and

(4) In operative position, that is when supporting a lamp, the space between the contact disk and the outer face of the yieldable contact is always slightly less than one-quarter of an inch and the tolerance length of the contact pin of the yieldable socket is always slightly more than one-sixteenth of an inch.

These and other features, capabilities and advantages of the invention will appear from the subjoined detailed description of specific embodiments thereof illustrated in the accompanying drawings, in which Fig. 1 is a transverse section of a socket fixture made according to one embodiment, and the Wiring, lamp and lamp pin associated with the fixed seat illustrated diagrammatically.

Fig. 2 is a section on the line 22 of Fig. 1.

Figs. 3, 4, 5 and 6 are transverse sections of four additional embodiments of the present invention.

Fig. 7 is an enlarged fragmental detail of the embodiment illustrated in Fig. 1.

In the embodiment illustrated in Fig. 1, the improved socket fixture 1 is shown in section and the connection thereof with a fixed socket fixture is shown diagrammatically. The fixture 1 consists essentially of a housing section 2 composed of a suitable insulating material which has a main terminal plate 3 provided with a screw 4 connected to the high voltage conductor 5 which in turn is connected to the ballast or transformer 6 from which, in the present instance, two conductors 7 and 8 extend, the conductor 7 extending to one line of the source of current, and the conductor 8 extending to one of the twin contacts 9, the other twin contact 10 normally being spaced from the contact 9 and being connected by the conductor 11 to the other line of the source of current. The contacts 9 and 10 are positioned in the sleeve 12 a distance of about five-sixteenths of an inch from the fixed socket having the fixed seat consisting of the disk 13 provided with the central opening 14 to receive the spherical or rounded head of the pin 15 of the single pin lamp 16. The other pin 17 of the lamp 16 conventionally having a spherical or rounded outer free end is provided to cooperate with the yieldable socket having the yieldable seat 18.

The yieldable seat 18 consists of the disk 19, in the present instance integral with the sleeve 20, the disk 19 having an opening 21 to receive the spherical or rounded head of the pin 15. The sleeve is slidably mounted in the cylindrical portion 22 of the housing section 23 secured to the main housing section 2. The main housing section 2 has a channel 24 therein to receive the conductor portion 25 connected at one end to the terminal plate 3 and at its other end being integral with the main strong spiral spring 26 which at one end surrounds the extension 27 formed on the main housing 2 and disposed in axial alinernent with the cylindrical chambers in the portion 22 and sleeve 20, the spring 26 extending from the extension 27 through the cylindrical chambers of the portion 22 and sleeve into engagement with the metal contact disk 28, in the present instance provided with a round central opening 29, which disk 28 in turn engages the insulating washer 30 which forms the seat or abutment for one end of the weak spiral spring 31, the other end of which spring 31 abuts against the disk 19 whereby the insulated housing sections 2, 20 and 22 composed of insulating material will supplement the washer 30 to prevent the current from the terminal plate 3 to pass to the pin 17 except through the disk 28.

The strengths and lengths of the springs 31 and 26 are determined so that they have different loading factors, the spring 31 to resist greater compression forces than the spring 26 will resist for the reasons now to be set forth. In practice, the authorities, such as the Underwriters Laboratory, have required that the distance between the outer face of the contact disk 28 and the outer face of the disk 19 be predetermined, conventionally onequarter of an inch. This requirement has created problems. As an instance, due in part to the difliculty of producing uniformly shaped spherical forms for the outer free ends of the pins 17 and to produce uniformly shaped rounded openings 29 in the contact disks 28, and due furthermore to the many other manufacturing variations conventionally encountered, it has been considered good practice arbitrarily to adopt a length of five-sixteenths of an inch for the lengths of the pins 17 measuring from the i outer free end of each pin 17 to the outer face 33 of the cap of its associated lamp 16, thus allowing a tolerance of one-sixteenth of an inch for the pin to find its final seat or, positive contact on the contact disk 28. Normally, this one-sixteenth of an inch tolerance would permit the desired positive contact between the head of the pin 17 and the contact disk 28 in the yieldable socket 18. However, because of the manufacturing variations aforesaid, this one-sixteenth of an inch tolerance does not always result in a positive contact and consequently objectionable arcing and accompanying burning of associated parts is encountered.

To overcome the aforesaid objection, according to the present invention, the loading factors of the springs 26 and 31 are in part determined to maintain the distance between the outer face of the contact disk 28 and the outer face of the disk 19 at the required predetermined distance, as an instance, one-quarter of an inch. Consequently, when the contact pin 17 of the lamp 16 is initially inserted into the yieldable socket 18,

(1) The initial pressure placed upon the yieldable socket 18 will be mainly taken up by the weaker spring 31 to insure a positive contact between the outer spherical free end of the contact pin 17 and the seat of the contact disk 28,

(2) After the position of the pin 17 in positive con tact relationship with the contact disk 28 has been effected, and the consequent ultimate compression of the spring 31 has been fixed, the ultimate compression necessary securely to accommodate the fluorescent lamp in positive contact with the contacts of the yieldable and fixed sockets is taken up by the stronger spring 26,

(3) In inoperative position, that is, when not supporting a lamp, the predetermined space required, one-fourth of an inch as an instance, between the contact disk 28 and the outer face of the yieldable contact 18, is maintained, and

(4) In operative position, that is, when supporting a lamp, the space between the contact disk 28 and the outer face of the disk 19 of the yieldable contact 18 is always slightly less than the predetermined required distance, one-quarter of an inch as an instance, and the tolerance length of the contact pin 17 in the yieldable socket 18 is always slightly more than one-sixteenth of an inch.

To anchor the sleeve housing section 23 to the housing section 2, screws, such as the screw 34, are provided which extend from the partition 35 of the housing section 23 face of the sleeve 22 terminating at 38 to receive projections, such as the projection 39, Fig. 2, on each side of the sleeve 20.

The embodiment shown in Fig. 3 differs from the embodiment shown in Fig. 1, primarily in that the insulating washer 30 is omitted and the sleeve 22 omitted, and

in place of the latter the disk 40 is provided forming the yieldable seat which in turn is provided with an annular shoulder 41 to rest against the shoulder 42 of the main housing 43 in expanded position of the springs 44 and 45. Here furthermore, the weak spring 44 is tapered with its large coil disposed inside of the shoulder 41 and its small coil disposed inside of the shoulder 46 of the contact disk 47, while the small coil of the strong spring 45 is disposed on the outside of the shoulder 46 with the large coil of the spring 45 disposed in the opening formed in the disk 48, which in the present instance constitutes a conductor connected to the outgoing line 49.

The embodiment shown in Fig. 4 differs from the embodiment shown in Fig. 1 primarily in that the insulating washer 30 is omitted, and that the sleeve 50 integral with the disk 51 constituting the yieldable seat, rides on the outside of the sleeve 52. Here furthermore, the large spring 53 is contained between the disk 54 at the inner end of the sleeve 52 and the flange 55 of the contact disk 56 with the small coil of the tapered weak spring 57 positioned adjacent the inside of the shoulder 155 of the disk 56, and the large coil of the Weak spring 57 engaging the inner face of the disk 51 adjacent the inner face of the cylindrical wall of the sleeve 50. The outermost position of the sleeve 50 is here effected by the engagement of the split ring 58 positioned in the recess 59 formed in the sleeve 50 abutting against the shoulder 60 formed on the inner sleeve 52.

The embodiments shown in Figs. 5 and 6 resemble the embodiment shown in Fig. 3 rather than the embodiments shown in Figs. 1 and 4 since here too the yieldable seat is not associated with an elongated sleeve, such as the sleeve 20 of Fig. 1, or the sleeve 50 of Fig. 4.

In Fig. 5, as an instance, the disk 61 having the central opening 62 is slidably mounted in the cylindrical chamber formed in the upper part of the housing 63 having an opening 64 slightly less in diameter than the diameter of the disk 61 so that an annular lip 65 is provided to form a stop for limiting the outward movement of the disk 61. Extending inwardly from the disk 61 adjacent the opening 62 there is an annular shoulder 66 on the outside of which the outer coil of the weak spring 67 engages, the inner coil of which is disposed inside of the shoulder 68 formed on the contact disk 69. The inner coil of the strong spring 70 engages the outer face of the shoulder 68 while the outer coil of the spring 70 engages the outer face of the annular shoulder 71 formed on the disk 72 which is connected to the conductor 73.

In Fig. 6, a cylindrical chamber is formed at one side of the housing 74 in which the disk 75 constituting the yieldable seat is slidably mounted, it having a pin receiving opening 76 and an annular shoulder 77 to abut against the annular shoulder 78 of the housing 74 to determine the outermost position of the disk 75. The weak spring 79 here has its outer coil engaging the outer face of the inwardly extending annular shoulder 80 formed adjacent the opening 76, while its inner coil engages the inner face of the shoulder 81 formed on the contact disk 82. In turn, the inner coil of the strong spring 83 engages the annular flange 84 around the shoulder 81, and the outer coil of the spring 83 engages the outer face of the projection 85 which is electrically connected to the conductor 86.

It will, of course, be apparent that the sleeves 20 and 50 are substantially parts of the disks 19 and 51, respectively, except that the outer ends of these disks are turned into aprons, constituting an exaggeration of the shoulders 41 and 77 of the embodiments shown in Figs. 3 and 6, which sleeves 20 and 50 and shoulders 41 and 77 may be omitted as shown in Fig. 5 when the outer edge of the disk 61 cooperates with the shoulder 65 of the housing 63, or in turn, looking at the invention from the standpoint of the sleeves 20 and 50, the shoulders 41 and 77,

although shorter than the sleeves 20 and 50, are substantially sleeves and the outer periphery of the disk 61 of the embodiment shown in Fig. 5 serves substantially the same function performed by the sleeves 26 and 5t and shoulders 41 and 77, when cooperating with the inner face of the cylindrical wall of the housing 63 to position the disk during its slidable motion and also to locate the outermost position of this disk.

It is obvious that various changes and modifications may be made to the details of construction without departing from the general spirit of the invention as set forth in the appended claims.

I claim:

1. A socket having a yieldable seat for cooperating with a socket having a fixed seat to support between the two a fluorescent lamp having a single pin terminal at each end, characterized by a chambered housing composed of insulating material, having an opening and having an internal abutment, a disk composed of insulating material having a narrow pin opening therein, said disk constituting a seat and being slidable relative to said abutment, a single contact, a first spiral spring for normally spacing said contact from said disk a predetermined distance when expanded and the coils of which spring in a radial direction when contracted elfectively clearing said narrow pin opening and spacing said contact from said disk a shorter predetermined distance, a second spiral spring in engagement with the said contact disposed in said housing and tensed between said abutment and said contact, said housing and disk cooperating to enclose said springs and contact, the second spring being less sensitive than said first spring so that compression on the seat by the lamp will initially be mainly taken up by said first spring until positive contact has been established whereupon any further compression necessary to accommodate the lamp between the socket fixtures will be absorbed by said second spring.

2. The combination as set forth in claim 1, characterized by a metal disk constituting said contact, and abutments formed on said housing to cooperate with said disk to determine its outermost position.

3. The combination as set forth in claim 1 in which said disk is characterized by a sleeve at its periphery slidably mounted in said housing and constituting the slidable support for said disk.

4. The combination as set forth in claim 1 in which said disk is characterized by a shoulder at its periphery slidably mounted in said housing and constituting the slidable support for said disk.

5. The combination as set forth in claim 1 in which an insulating Washer is interposed between said contact and said first yieldable means.

References Cited in the file of this patent UNITED STATES PATENTS 2,412,826 Mills et a1. Dec. 17, 1946 2,446,154 Haven July 27, 1948 2,495,196 Kulka Jan. 17, 1950

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