US3329924A

US3329924A - Fluorescent lampholders with breakage resistant plunger stop arrangement

Info

Publication number: US3329924A
Application number: US461846A
Authority: US
Inventors: Jr Wallace H Henshaw
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1965-06-07
Filing date: 1965-06-07
Publication date: 1967-07-04
Anticipated expiration: 1984-07-04

Description

w. H. HENSHAW, JR 3,329,924 FLUORESCENT LAMPHOLDERS WITH BRBAKAGE RESISTANT PLUNGER STOP ARRANGEMENT July 4, 1967 Filed June '7, 1965 2 Sheets-Sheet 1 I Attarwqg.

y 4, 1967 w. H. HENSHAW, JR 3,

FLUORESCENT LAMPHOLDERS WITH BREAKAGE RESISTANT PLUNGER STOP ARRANGEMENT Filed June 7, 1965 2 Sheets-Sheet 2 4 orwey United States Patent 3,329,924 FLUORESCENT LAMPHOLDERS WITH BREAK- AGE RESISTANT PLUNGER STOP ARRANGE- NIENT Wallace H. Henshaw, Jr., Trumbull, Conn., assignor to General Electric Company, a corporation of New York Filed June 7, 1965, Ser. No. 461,846 11 Claims. (Cl. 339-52) This invention relates generally to electric wiring devices and more particularly to lampholders for mounting gaseous discharge lamps such as fluorescent lamps.

In order to support an elongated fluorescent lamp of the high output type, it is customary to provide a pair of lampholders. One of the lampholders with a retractable spring-biased plunger, generally referred to as the telescopic lampholder is used to support the fluorescent lamp at one end while a lampholder of the fixed type is used at the other end. With such a set of lampholders, it is possible to mount the fluorescent lampby inserting one end of the lamp into the lampholder with the springbiased plunger and depressing the plunger until the other end of the lamp can be inserted into the other lampholder of the set. With the lamp engaged between the lampholders, a resilient support is provided for the fluorescent lamp. The lampholders also serve as sockets for energizing the lamps from a fluorescent lamp ballast.

lit will be appreciated that considerable length of travel is required for the plunger of the telescopic lampholder. When the spring-biased plunger is pushed inwardly, one or a pair of springs is being compressed as the plunger travels into the cavity of the lampholder. If the spring biased plunger is released from its retracted position, the spring forces the plunger outwardly. A boss on the plunger engages a flange formed in the lampholder housing and thereby stops the plunger in its extended position.

In conventional plunger stop arrangements a sudden release of the plunger from its retracted position not too infrequently causes the boss or the flange of the lampholder to break thereby causing permanent damage to the lampholder. Thus, such conventional arrangement for stopping the travel of a retractable plunger have not been entirely satisfactory in practice because of the susceptibility to breakage. Further, materials commonly used to fabricate the lampholder plunger and housing are the phenolic and urea-formaldehyde resins which have a relatively hard and low impact strength. Although more expensive materials are available with more suitable strength properties, it has not been commercially desirable to use these materials because of the added cost to the end product.

Accordingly, a general object of my invention is to provide a new and improved telescopic lampholder construction.

A more specific object of my invention is to provide a new and improved lampholder wherein possible breakage of the lampholder parts, when the plunger is suddenly released from its retracted position, is substantially reduced.

In accordance with one form of my invention I have provided a lampholder embodying an improved arrangement for stopping a retractable plunger when it is suddenly-released from a retracted position. In the lampholder, which I have used to illustrate my invention, the lampholder housing is formed with a plunger-receiving chamber member. A contact support plunger or member is slidably mounted within the plunger-receiving chamber member for movement between an extended position and a retracted position. At least two or more slots are provided in one of the members, either the contact support member or the plunger-receiving member, and an equal number of slot-engaging projections are provided on the other member to guide the movement of the plunger member from the retracted position to the extend position and vice versa.

Each elongated slot and slot-engaging projection is formed with a front end portion. When an associated pair of front end portions is engaged, the spring-biased movement of the contact support member from a retracted position is stopped. At least one front end portion of an associated pair of front end portions includes a slanted or inclined surface. The other front end portion of the associated pair of front end portions includes an impact part. The impact part is arranged with respect to its associated slanted surface so that whenever the contact support member is suddenly released from its retracted position, one impact part will initially strike its associated slanted surface to deflect the movement of the contact support member. The impact part of another associated pair of front end portions then strikes its associated slanted surface to effect another deflection of movement of the contact support member before it is finally stopped in the extended position. Preferably, at least two such deflections should normally be produced to minimize the impact produced by the contact support member striking the lampholder housing.

An important advantage resulting from the improved plunger stop arrangement is that breakage of lampholder components is substantially reduced. The assembly of the lampholder may require that the plunger be depressed to a retracted position in order to facilitate installing the lampholder on the fixture and breakage frequently occurs during assembly. The improved arrangement is particularly advantageous in reducing breakage while lampholders are assembled on fluorescent lamp fixtures. Also, with the improved arrangement it is possible to reduce breakage that occurs when the lamp is suddenly removed from a lampholder and the plunger is suddenly released from its retracted position.

Further aspects of my invention will become apparent upon consideration of the following more detailed description. The subject matter which I regard as my invention is set forth in the appended claims. The invention, however, together with further objects and advantages thereof may be best understood by referring to the following description taken in conjunction with the accompanying drawings in which:

FIGURE 1 is a side elevational view showing one end of a fluorescent lamp supported in a telescopic lampholder embodying one form of the invention, the retractable plunger being shown in its retracted position;

FIGURE 2 is an enlarged bottom view of the lampholder shown in FIGURE 1 with the housing and plunger sectionalized to show the position of the plunger and springs when the plunger is in the retracted position;

FIGURE 3 is a bottom view corresponding to the View shown in FIGURE 2 with the housing cut away to show the position of the plunger and springs when the plunger is in an extended position;

FIGURE 4 is a fragmentary front elevational view of the lampholder shown in FIGURE 3;

FIGURE 5 is an exploded view of the lampholder;

FIGURE 6 is an enlarged view, partly in perspective and as seen from the general direction indicated by the arrow 6 in FIGURE 3, of the slot formed in the plungerreceiving opening with the slot-engaging projection being shown in section;

FIGURE 7 is a view corresponding to the view shown in FIGURE 6 illustrating a modification of the configuration of the slot-engaging projection and slot front end portion that can be employed in the practice of another form of the invention;

FIGURE 8 is a view corresponding to the view shown in FIGURE 6 illustrating another modification in the shape of the front end portions of the slot and slot-engaging projection that can be utilized in the practice of the invention; and 7 FIGURE 9 is a view, partly in section, illustrating still another modification in which an inclined surface is provided at the front end portion of the slot and extends transversely across the slot.

Having more specific reference now to FIGURE 1 of the drawing, I have illustrated therein a lampholder 10 embodying one form of my invention and supporting the left end of a fluorescent lamp 11 of the bi-pin type. The lampholder 10 is supported on a bracket 12 attached to a support member 13 by screws 14, 15. The support member 13 may form the part of the lighting fixture or other surface on which it is desired to attach the lampholder. It will be understood that the fluorescent lamp 11 Y is normally supported at the other end by a lampholder (not shown) that provides 'a supprt for the right end 7,

of the lamp. 7

As is well known, the fluorescent lamp 11 is usually inserted into a set of two lampholders by first depressing a spring-biased plunger 16 into the lampholder sufiiciently so that the right end of the fluorescent lamp 11 can then be inserted in the other lampholder (not shown).

It will be apparent that for a given lamp length a set of lampholders must be mounted and attached to a support in a predetermined spaced relation.

Referring now more specifically to FIGURES 16, in j which like numerals have been used to denote the corresponding parts in all of the figures, I will now more particularly describe the construction of the improved lampholder 10 embodying one form of the invention. It will be seen that lampholder 10 includes a housing 17 comprised of front and

rear housing sections

18, 19 joined to form a unitary housing structure by a suitable securing means such as a rivet 20 (see FIGURE 4). When the

housing sections

18, 19 are assembled, all of the component parts of the lampholder are located and locked in their proper assembled relation. The

housing sections

18, 19 and the spring-biased plunger 16 are formed from any suitable insulating material such as phenolic or urea-formaldehyde resins.

As'is best seen in FIGURES 3, 4 and 5, the plunger 16 is essentially cylindrical in shape and has a pair of opposed radially extending slot engaging projections or

extensions

22, 23 integrally formed thereon. The slot-

engaging projections

22, 23 are slidably disposed in a pair of opposed

elongated slots

24, 25 to guide the travel of the plunger 16 between its extended position (FIGURE. 3) and its retracted position (FIGURE 2). It will be seen in FIGURE 5 that when the housing sections 18 and ends of the

springs

33, 34 are biasingly; engaged with

contact strips

43, 44 at one end. At the other end the contact strips 43, 44 (see FIGURE 5) provide pressure= lock terminal for external leads from a fluorescent ballast.

or other power source. Since the contact strips 43, 44 and springs 33, 34 are a part of the electrical circuit, they are formed from any suitable electrically conductive material, such as an alloy of copper.

In FIGURE 6, I have illustrated a fragmentary portion of the lampholder housing section 18 as viewed from the inside of the plunger-receiving opening 32. Also, shown in FIGURE 6 is a sectionalized view of the slot-engaging projection 22. .It will be appreciated that the front ends 45, 46 (the. ends adjacent to the lamp) of both the

opposed slot portions

26, 28, as seen in FIGURE 5, have essentially the same shape. Also, the pair of

opposed slotengaging projections

22, 23 formed integrally on the plunger 16 have essentially the same configuration. Thus, the description of the slot-engaging projection 22 and slot portion 26 is equally applicable to the other corresponding slot portion and slot-engaging projection.

An important feature of the present invention is the provision of an inclined surface 47 for engagement with the front end portion of projection 22. Preferably, the

angle of this inclined surface is selected to minimize the a It will be appreciated that when the plunger 16 is suddenly released from a retracted position, the slot-engag- 19 are assembled, the

slot portions

26, 27 and 28, 29 are 7 oined to form the pair of elongated slots '24 and 25 respectively. The rear ends 30 of the slot portions 27, 29 (see FIGURE 5) serve as a stop for the plunger 16 when it is pushed'to a fully retracted position.

. The plunger 16 is biased outwardly through an opening

contacts

35, 36. When the

springs

33, 34 are compressedas shown'in FIGURE 2, the

springs

33, 34 bias the plunger 16 outwardly and also bias

thecontacts

35, 36

outwardly from each other so that the contacts make a positive resilient connection with lamp pins or inleads ;32- by means of a pair of laterally spaced

current conductf

37, 38. Asis best seen in FIGURE 2, thecontacts are" a formed with coined projections 39, 40 respectively and pivot aboutthe shoulders 41, 42 so that the springs-urge the

contacts

35,36 against the lamp inleads 37, 38, The

coined projections 39, 40 serve as a stop for the pivotal movement of the

contacts

35, 36 when the plunger 16 is in the fully'extended position.

In order that an electrical connection be provided between the

springs

33, 34 and contact strips'43, 44, the

ing projection 22 will not generally travel precisely on the longitudinal center line of theslot portion 26. Let

use assume that when the slot-engaging projection 22 initially strikes the inclined surface of the slot, it is in the position shown in dashed outline in FIGURE 6. When the impact part 48 strikes the inclined surface 47, it will glance off, and then the other impactjpart 49 will strike the lower inclined. surface 50 of slot portion 26. The plunger bounces back and forth until it is finally seated in the fully extended position. I have found that such a plunger stop arrangement minimizes the possibility of lampholder breakage. It will be understood that in the embodiment of my invention, which I have illustrated in FIGURE 6, the

surfaces

51, 52 formed on the frontend portion of slot-engaging projection 22 are provided for the purpose of facilitating entry of the slot-engaging pro 7 jection into the slot portion 26. By way of illustration of a another modification, I have shown in FIGURE 7 a front end 53 of a slot-engaging projection 54 that is es-,

sentially squared off.

In the practice of the present invention, it will be understood that the inclined surface used to produce the desired deflections of'the plunger 16 may be formed either on the slot or plunger. Animportant feature of the present invention is that the inclined surface, whether it is formed on the slot or plunger, is that it will cause the plunger initially to strike the housing at. several points before it is seated in the extended position. a

In FIGURE 8 I have illustrated another modification of the slot-engaging projection and slot wherein a pair of impact shoulders 54, 55 are formed at the front end of a slot portion 56 and a pair of

inclined surfaces

57, 58 are formed on a slot-engaging projection 59. Near the end of .another view of a section taken through a slot portion formed at various locations to achieve the desired results in accordance with the invention. The angle of inclination of the surface with respect to the longitudinal axis of the slot should be preferably less than 80 degrees and greater than degrees in order to minimize the impact force on the housing section. Also, this angle of inclination should be greater than the friction and plastic locking angles of the insulating materials used in the fabrication of the housing sections and the plunger in order to prevent the plunger from jamming into the housing section.

From the foregoing description it will be apparent that I have provided a lampholder construction utilizing an improved plunger stop arrangement. An important advantage of the improved arrangement is that the possibility of breakage is minimized when the spring loaded plunger is suddenly released from a retracted position. It was found that the use of the impact deflecting surfaces to take up the impact forces substantially reduce the possibility of damage to the lampholder during manufacture and whenever the spring-loaded plungers are compressed and suddenly released.

While I have described herein exemplifications of the invention wherein the slot-engaging projections were formed on lampholder plungers, it will be apparent to those skilled in the art that, for example, the slot-engaging projections may be formed in the plunger-receiving opening of the lampholder housing and that the slots may be formed in the plunger. Also, it will be apparent that the inclined surface need not be planar but may be, for example, conical in shape. Thus, it will be understood that various other changes and modifications may be made without departing from the invention. It is therefore intended in the following claims to cover all such equivalent variations as come within the true spirit and scope of this invention.

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

1. A lampholder for an electric discharge lamp, said lampholder comprising a housing having a plunger-receiving opening formed therein, a retractable plunger slidably mounted in said plunger-receiving opening, a pair of spaced contacts mounted in a wall of said plunger and movable relative to said plunger, terminal means for providing connections with external electrical leads, a pair of current conducting springs in said housing, one end of said current conducting springs engaging said' contacts to bias said contacts pivotally and to bias said plunger outwardly of said plunger-receiving opening from a retracted position to an extended position, means at the other end of said springs for providing an electrical connection between the current conducting springs and said terminal means, at least a pair of oppositely disposed elongated slots formed in said housing and extending toward said plunger-receiving opening for guiding the movement of said retractable plunger between said retracted and extended positions, a pair of slot-engaging projections formed on said plunger and extending into said elongated slots, each of said slot-engaging projections having an impact member formed at the front ends thereof, each of said elongated slots formed with at least one surface generally inclined relative to the direction of movement of said slot-engaging projection and engageable with said surface to deflect the movement of the members of said slot-engaging projections when the lampholder is near the end of its travel to the extended position.

2. A lampholder for an electric discharge lamp having at least one inlead for energization from an electrical current source, said lampholder comprising a housing of insulating material including a plunger-receiving member with an opening formed therein, a retractable plunger slidably mounted in the opening of said plunger-receiving member for movement between an extended position and a retracted position, spring means disposed between said retractable plunger member and said housing to cause said plunger member to be biased to the extended position, contact means carried on said plunger member, one of said members having a pair of elongated slots, the other of said members having formed thereon slot-engaging projections extending into said elongated slots for guiding the travel of said plunger member between extended and retracted positions, each of said slots and said slot-engaging projections having a front end portion, one of said front end portions having at least one surface generally inclined relative to the direction of movement of the retractable plunger member, the other front end portion having an impact part associated with one of said inclined surfaces, whereby when the plunger member is released from the retracted position, normally one of the impact parts strikes the inclined surface associated therewith to cause a first deflection of said plunger member to change and to cause another impact part to strike the inclined surface associated with it and cause at least a second deflection of said plunger member before said plunger member is seated in the extended position.

3. The lampholder set forth in claim 2 wherein the sloten gaging projections are formed in said retractable plunger member and said elongated slots are formed in said plunger-receiving member.

4. The lampholder set forth in claim 2 wherein each front end portion of the slot-engaging projections includes a pair of spaced inclined surfaces.

5. The lampholder set forth in claim 2 wherein the inclined surface has an angle of inclination of not less than 10 degrees and not more than degrees with respect to the longitudinal axis of the elongated slot.

6. A lampholder for a fluorescent lamp having at least one inlead for energization from a power supply, a said lampholder comprising an insulating housing formed with a plunger-receiving member having an open end, a hollow contact support member slidably mounted in said plunger-receiving member for movement between a retracted position and an extended position, said contact support member extending through the open end of said housing when in the extended position, spring means disposed between the hollow cont-act support member and the housing to normally cause said hollow contact support member to be biased to the extended position, contact means carried in said hollow contact support member for engagement with an inlead of the fluorescent lamp, one of said members having a pair of elongated slots formed thereon, the other of said members having a pair of slot-engaging projections engaged in said elonated slots for guiding the movement of the contact support member from a retracted position to the extended position, each of said elongated slots and said slot-engaging projections having a front end portion, one of said front end portions formed with at least one slanted surface inclined with respect to the direction of travel of the slot engaging projection, and the other front end portion associated therewith having an impact part aligned with one of said slanted surfaces to cause the hollow contact support member to be deflected back and forth before the contact support member is seated in the extended position after being released from a retracted position.

7. The lampholder set forth in claim 6 wherein said slot-engaging projections are formed on said plunger-receiving member and said slot-engaging projections are a formed in the plunger-receiving member.

8. The lampholder set forth in claim 6 wherein said slanted Surfaces have an angle of inclination with respect to the general line of direction of the contact support member that is not less than 10 degrees and not more than 80 degrees.

'9. A lampholder for an electric discharge lamp having at least one inlead for energization source of electrical current, said lampholder comprising an openended insulating housing having a plunger-receiving member, a hollow contact support member slidably mounted in said plunger-receiving member, contact means carried on said hollow contact support member for engagement with 'an inlead of the electric discharge lamp, at least a pair of slot-engaging extensions formed on one of said members, at least a pair of elongated slots formed on the other of said members and extending generally along a longitudinal axis, said slot-engaging extensions'being movably disposed in the slots formed in the said ,other member to slidably guide the hollow contact support member between a retracted position and an extended position, spring means supported between said housing and said hollow contact support member to bias said hollow contact support member outwardly toward the extended position, each of said elongated slots and said slot-engaging extensions having a front end portion, one of said front end portions having an impact part and the other of said front end portions having a slanted surface for engagement with the associated impact part, said impact part striking said slanted surface to deflect the movement of the hollow contact support member when it is near the end of its travel to the extended position thereby tot minimize the a resulting impact.

10. The lampholder set forth in claim9 wherein at least one of said slanted/surfaces has an angle of inclination of not less than 10 degrees and not greater than 80 degrees with respect to the longitudinal axis of said elongated slot associated therewith.

' 11. A lampholder for a fluorescent lamp having at least low movable contact support member slidably mounted in said plunger-receiving member for movement between a retracted position and an extended position, said movable contact support member extending through saidopen' end of said housing when in the extended position, spring means disposed between the hollow movable contact support member and the housing to normally bias said movable contact support member to the extended position, contact means carried by the movable contact support mem-' ber and engageable with an inlead of a fluorescent lamp, said movable contact support member having a projection extending circumferentially over at least a portion of said support member, said projection having a front end portion, said plunger-receiving member having a slanted sur-- face inclined with respect to the direction of travel of said front end portion of the projection, said slanted surface having an angle of inclination with respectto said direction of travel that is not less than 10 degrees and not more than degrees, and said slanted surface being engageable with said front end portion of said projection when the movable contact support member is returned to the extended position to cause said plunger-receiving member to be deflected at least once before the plunger-receiving member is seated in the extended position.

7 References Cited UNIT ED STATES PATENTS 2,651,024 9/1953 Miller .V 33945 2,883,639 4/1959 Kulka 339, ss. 2,977,563 3/1961 Lennox 339 ss MARVIN A. CHAMPION, Primary Examiner.

I. H. MCGLYNN, Assistant Examiner.

Claims

1. A LAMPHOLDER FOR AN ELECTRIC DISCHARGE LAMP, SAID LAMPHOLDER COMPRISING A HOUSING HAVING A PLUNGER-RECEIVING OPENING FORMED THEREIN, A RETRACTABLE PLUNGER SLIDABLY MOUNTED IN SAID PLUNGER-RECEIVING OPENING, A PAIR OF SPACED CONTACTS MOUNTED IN A WALL OF SAID PLUNGER AND MOVABLE RELATIVE TO SAID PLUNGER, TERMINAL MEANS FOR PROVIDING CONNECTIONS WITH EXTERNAL ELECTRICAL LEADS, A PAIR OF CURRENT CONDUCTING SPRINGS IN SAID HOUSING, ONE END OF SAID CURRENT CONDUCTING SPRINGS ENGAGING SAID CONTACTS TO BIAS SAID CONTACTS PIVOTALLY AND TO BIAS SAID PLUNGER OUTWARDLY OF SAID PLUNGER-RECEIVING OPENING FROM A RETRACTED POSITION TO AN EXTENDED POSITION, MEANS AT THE OTHER END OF SAID SPRINGS FOR PROVIDING AN ELECTRICAL CONNECTION BETWEEN THE CURRENT CONDUCTING SPRINGS AND SAID TERMINAL MEANS, AT LEAST A PAIR OF OPPOSITELY DISPOSED ELONGATED SLOTS FORMED IN SAID HOUSING AND EXTENDING TOWARD SAID PLUNGER-RECEIVING OPENING FOR GUIDING THE MOVEMENT OF SAID RETRACTABLE PLUNGER BETWEEN SAID RETRACTED AND EXTENDED POSITIONS, A PAIR OF SLOT-ENGAGING PROJECTIONS FORMED ON SAID PLUNGER AND EXTENDING INTO SAID ELONGATED SLOTS, EACH OF SAID SLOT-ENGAGING PROJECTIONS HAVING AN IMPACT MEMBER FORMED AT THE FRONT ENDS THEREOF, EACH OF SAID ELONGATED SLOTS FORMED WITH AT LEAST ONE SURFACE GENERALLY INCLINED RELATIVE TO THE DIRECTION OF MOVEMENT OF SAID SLOT-ENGAGING PROJECTION AND ENGAGEABLE WITH SAID SURFACE TO DEFLECT THE MOVEMENT OF THE MEMBERS OF SAID SLOT-ENGAGING PROJECTIONS WHEN THE LAMPHOLDER IS NEAR THE END OF ITS TRAVEL TO THE EXTENDED POSITION.