EP0704101A1

EP0704101A1 - Bulb mounting arrangement for an electrodeless discharge lamp

Info

Publication number: EP0704101A1
Application number: EP95914456A
Authority: EP
Inventors: Allan Gould; Kenneth Downton
Original assignee: GE Lighting Ltd
Current assignee: GE Lighting Ltd
Priority date: 1994-04-11
Filing date: 1995-04-06
Publication date: 1996-04-03
Anticipated expiration: 2015-04-06
Also published as: WO1995027995A1; CA2164708A1; EP0704101B1; DE69511975T2; JPH08511650A; GB9407132D0; DE69511975D1

Abstract

A mounting arrangement for mounting a lamp envelope (14) to a lamp base (12) for an electrodeless fluorescent discharge lamp (10) includes a bulb mounting clip (36) having a center support portion and a plurality of arms (44) extending therefrom. Each of the plurality of arms (44) is formed having at least two curved portions one of which contacts a ridge portion (12a) formed on the lamp base to secure the bulb mounting clip (36) to the lamp base (12). The second curved portion (42) of each of the plurality of arms (44) contacts an indention formed in the region of the lamp envelope (14) which fits within the lamp base (12). The contacting relations between the lamp base (12) and lamp envelope (14) achieved by use of the bulb mounting clip (36) are effective to prevent rotational movement of the lamp envelope (14) relative to the lamp base (12). The plurality of arms (44) are in contacting relation to the lamp envelope (14) such that, if excessive force is exerted on the lamp envelope (14), the lamp envelope (14) will break first within the lamp base (12) rather than on the outer envelope area.

Description

BULB MOUNTING ARRANGEMENT FOR AN ELECTRODELESS DISCHARGE LAMP

FIELD OF THE INVENTION The present invention relates to an arrangement for mounting the lamp envelope portion of an electrodeless discharge lamp to the base portion of such lamp and more particularly, to such a mounting arrangement as provides for a complete mechanical failure in the event of damage to the lamp as can occur for instance by mishandling.

BACKGROUND OF THE INVENTION

Electrodeless discharge lamps are expected to become increasingly popular for home, industrial and commercial uses because of the obvious advantages of energy efficiency and long life over the standard incandescent and even other compact fluorescent products which are electroded. In an electrodeless discharge lamp, an ionizable medium is excited to a discharge state by introduction of an radio frequency (RF) signal and light is produced from such discharge by use of a suitable phosphor. An example of such a lamp can be found in US Patent No.4,010,400 wherein it is disclosed that an electric field generated by the RF signal initiates the ionization that produces visible light output whereas a magnetic field then sustains ionization for continuous lamp operation. The lamp envelope in this instance is shown in the shape of a typical A-line incandescent lamp having a central cavity through which a coil member is disposed, such coil member being effective for coupling the RF signal to the ionizable medium. The lamp envelope is then shown being mounted on a base member in which a ballast circuit effective for generating the RF signal is disposed. Though no discussion is provided in this patent for the actual manner by which the lamp is mounted to the lamp base, it is known that some form of adhesive could be used to both secure the envelope to the base and to provided a seal therebetween. The problem with such a mounting arrangement particularly with a potentially long lasting lamp such as the electrodeless discharge lamp is that the adhesive has a potential for degradation at a joint where safety is a critical factor. Moreover, for other safety reasons, it is important to insure that the lamp envelope will definitely be rendered inoperative before it can be separated from the lamp base, such feature is not guaranteed for a lamp which utilizes an adhesive mounting arrangement.

Accordingly, it would be advantageous if a mounting arrangement for mounting a lamp envelope to a lamp base could be provided for use with an electrodeless discharge lamp wherein such mounting arrangement would not be subject to degradation over time and wouldjnsuπe that upon damage to the lamp as may occur by mishandling for instance, the lamp is definitely disabled before it could be separated from the lamp base.

SUMMARY OF THE INVENTION

Based on the principles of the present invention, there is provided a mounting arrangement for mounting a lamp envelope to a lamp base which includes a mounting member having a center support portion and a plurality of arms extending outwardly therefrom. The plurality of arms may have formed thereon, at least two curved portions, the first of which is effective for contacting a ridge portion of the lamp base and thereby securing the mounting member to the lamp base. The second curved portion of each of the arms contacts an indention portion formed at the lower region of the lamp envelope which fits into the lamp base, the second curved portion of the plurality of arms contacting such indention portions in a manner to secure the lamp envelope to the mounting member which is secured to the lamp by virtue of the first curved portion contacting the ridge portion of the lamp base.

In another embodiment of this invention, it is possible to form the mounting member having an outer circular ring portion which contacts the ridge portion of the lamp base to secure the mounting member to the lamp base. In this instance, the plurality of arms need only include a single curved portion for contacting the indention portion of the lamp envelope and thereby securing the lamp envelope to the mounting member which has been secured to the lamp base by way of the circular ring portion contacting the ridge portion of the lamp base. It is also possible to provide bent or offset arms in cooperation with the central ring portion.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1- is a sectional view of an electrodeless discharge lamp constructed in accordance with the teachings of the prior art.

Figure 2 is an elevational view in section of a lamp envelope and lamp base configuration for an electrodeless discharge lamp constructed in accordance with the principles of the present invention.

Figure 3 is an elevational view of a bulb clip device used in conjunction with the lamp envelope and lamp base configuration shown in Fig. 2.

Figure 4 is an elevational view of another bulb clip device used in conjunction with an alternate lamp envelope and lamp base configuration constructed in accordance with the principles of an alternate embodiment of the present invention.

Figure 5 is an elevational view in section of yet another bulb clip arrangement constructed in accordance with the principles of the present invention.

Figure 6 is an elevational view in section of still another bulb clip arrangement constructed in accordance with the principles of the present invention. DETAILED DESCRIPTION OF THE INVENTION

With reference to Fig. 1, it can be seen that an electrodeless fluorescent lamp 10 includes a lamp base portion 12 and a lamp envelope portion 14. When finally assembled, the lamp; 10 can resemble a conventional A-line incandescent lamp, or it can be shaped as a reflector lamp as shown in Figure 1. The base portion 12 is constructed having a conventional edison type threaded base 13 capable of easy installation in a conventional light socket typically used in conjunction with a standard incandescent lamp. A housing portion 22 is formed adjacent the threaded base 12a and serves to contain the ballast circuit 24 which receives the line power and converts such line power into an operating signal capable of driving the electrodeless lamp 10 to a discharge state. A core member 20 which extends from the housing portion 22 is made of a magnetizable material and has wound thereon, an excitation coil 18. The excitation coil 18 is effective in conjunction with a capacitor (not shown) disposed within the housing portion 22, for forming a resonant circuit which receives the operating signal from the ballast circuit 24 and develops the RF signal therefrom. The RF signal is then inductively coupled to a gas fill contained within the lamp envelope 14 so as to initiate and maintain the gas discharge 23 within the lamp envelope 14. The inner surface of the lamp envelope 14 is coated with appropriate fluorescent materials shown generally as reference 21, such fluorescent materials being selected from a group of known materials and applied to the inner surface in a known manner. With the RF energy coupled to the gas fill as previously described, the molecules which make up the gas fill are ionized first by an electric field generated by the RF signal and thereafter maintained in such discharge state by a magnetic field also produced by the RF signal. The resulting gas discharge is then used to produce visible light by the known principles of fluorescent lighting. In setting forth the principles of operation for an electrodeless fluorescent lamp 10, the prior electrodeless fluorescent lamps as shown in U.S. 4,010,400 provide no direction regarding the manufacture of such a lamp nor specific teachings regarding certain safety features of the lamp. For instance, as seen in Fig. 1 or U.S. 4,010,400, the manner of attaching the lamp envelope to the lamp base merely shows a lower tapered portion of the lamp envelope 14 fitting into a lip region associated with the lamp base. One skilled in the art of lamp manufacture would most likely use an adhesive arrangement for securing purposes. The disadvantage with such an adhesive arrangement however is that because of the expected long life of an electrodeless discharge lamp 10, the adhesive used may deteriorate before the end of the life of the lamp 10. In order to address this problem, the present invention provides an arrangement which mechanically secures the lamp envelope 14 to the lamp base 12 so as to provide an expected life at least as long as the lamp 10. In addition, the present invention also provides an added safety feature in that, should the lamp envelope 14 be subjected to excessive forces by mishandling for instance, the lamp securing arrangement as will be described with reference to Fig. 2, will operate to disable operation of the lamp 10.

As further seen in Fig. 1, the electrodeless fluorescent lamp; 10 of the present invention further includes a re-entrant cavity portion 15 of the lamp envelope 14. The core member 20 extends into the re-entrant cavity 15. An exhaust tube 16 extends through the center of the re-entrant cavity 15.

As seen in Fig.2, an electrodeless fluorescent lamp 10 constructed in accordance with the present invention incorporates the safety feature which provides for the lamp shutdown in the event of an excessive force being exerted on the lamp envelope and further, which addresses the above discussed life expectancy problem related to the envelope, base securing arrangement. Electrodeless fluorescent lamp 10 provides that the lamp base member 12 and a lamp envelope 14 which are cooperatively interlocked by means of a bulb clip member 36 as will be more fully described with reference to Figs. 3 through 6. With the ballast circuit components disposed within the lower portion of the base member 12, the bulb clip member 36 will reside within the top portion of the lamp base 12 as depicted in Fig. 2. At the upper end of the bulb clip member 36, a plurality of arm ends 44a ( see Fig. 3) contact a lip portion 12a formed along the upper inner rim of the lamp base member 12. In this manner, the bulb clip member 36 is prevented from being pulled away from the lamp base 12 and, as will be described hereinafter in further detail, further prevents the pulling out of the lamp envelope 14 from the lamp base 12. Though the lip portion 12a prevents movement of the bulb clip member 36 and the lamp envelope 14 out of the lamp base 12, it can be appreciated that such lip portion 12a may not prevent the bulb clip member 36 from dislocating to a position further within the lamp base member 12. As a means of support for preventing the bulb clip member 36 from dislocating to a position within the lamp base 12, it is possible to provide a lower stop member 38 disposed on the inner surface of the lamp base 12 at a point just below the bottom portion of the bulb clip member 36. Of course, once the lamp envelope 14 is fitted within the bulb clip member 36, it is also possible to rely on the support of the lamp envelope 14 contacting the topmost portion of the lamp base 12 in order to prevent the bulb clip member 36 from falling to a lower position within the lamp base 12. It is also possible to provide a sealing ring (not shown) around the point at which the topmost portion of the lamp base 12 contacts the lamp envelope 14; this sealing ring could cushion this junction point as well as provide a barrier for preventing dirt, moisture or other materials from entering the lamp base member 12. As further seen in Fig. 2, the bulb clip member 36 has a central opening 40 through which the core member 20 and the excitation coil 18 extend into the re-entrant cavity 15 of the lamp envelope 14. Additionally, the bulb clip member 36 includes a plurality of curved portions 42 which are effective for retaining a flared end portion 14a of the lamp envelope 14. The flared end region 14a of the lamp envelope 14 can be formed in a continuous annular manner or, in the alternative, can include at least one stop portion (not shown) formed along the surface of the lamp envelope 14. This stop portion can be effective for engaging a side portion of one of the arm extensions 44a of the bulb clip member 36 thus preventing the rotation of the lamp envelope 14 relative to the bulb clip member 36 or the lamp base 12.

As hereinabove discussed, the securing arrangement between the lamp envelope 14 and the lamp base 12 is one that, should an excessive force be exerted on the lamp envelope 14, a lamp shutdown will occur. This lamp shutdown is affected by use of the bulb clip member 36 which can be constructed of a metal having a spring coefficient that allows for the flexing of the extension arms 44 as shown in Fig. 3. The bulb clip member 36 can also be constructed of a high temperature, non¬ conducting plastic material. Referring again to Fig. 2 and the manner by which the bulb clip member 36 contacts the lip portion 12a of the lamp base, it can be seen that any excessive pulling force exerted on the lamp envelope 14 will result in the flared end portion 14a of the lamp envelope 14 transferring such force to the region of the curved portions 42 of the bulb clip member 36. Sincere bulb clip member 36 is constructed of a resilient material, such force on the curved portion 42 will be translated in a direction away from the longitudinal axis of the electrodeless lamp 10 to exert a further force between the plurality of arm ends 44a to the lip portion 12a of the lamp base member 12. Should this force be increased above a threshold level, the result will be a breakage of the lamp envelope 14 at the point where the flared end portion 14a contacts the curved portions 42 of the bulb clip member 36. In this manner, the lamp 10 is effectively shut down by the fact that a no discharge condition will alter the loading on the ballast 24 thereby causing the circuit to shut down. Additionally, with the provision of at least one stop portion on the surface of the lamp envelope 14 at the flared end region 14a, if an excessive rotational force is exerted on the lamp envelope, the stop portion will contact the side of the extension arm 44a of the bulb clip member 36 such that a breakage will occur thus effectively shutting down the electrodeless lamp 10 under these conditions as well. The bulb clip member 36 described in the lamp structure of Fig. 2, is more clearly illustrated in Fig. 3 where it can be seen that a plurality of extension arms 44a extend from a central hub portion 46 having the opening 40 formed centrally therein. As illustrated in Fig.3, there are four extension arms 44a extending from the central hub 46 spaced equally about the circumference of the central hub 46 so that the force needed to retain the lamp envelope 14 in the lamp base 12 is equally distributed. It should be understood that the benefits of the present invention could be equally well enjoyed by the provision of a different number of extension arms as that illustrated in this figure and that any variation of such number of arms is within the scope of the present invention. The curved portions 42 formed on the extension arms 44a are sized to correspond closely to the flared end portion 14a groove of lamp envelope 14. There is another bend portion formed in each extension arm, such bend 48 being effective for achieving the force transfer feature previously discussed. As seen in Fig. 4, an alternate bulb clip arrangement 50 to that shown in Fig. 3 includes an annular ring portion 52 with a plurality of extension arms 54 extending downward and in an inwardly direction relative to the annular ring 52. Each of the plurality of extension arms 54 includes a curved portion 54a similar to the curved portions 42 of the bulb clip member 36 of figs. 2 and 3, such curved portions 54a of alternate bulb clip member 50 also serving to contact the flared end region 14a of the lamp envelope 14 and secure the lamp envelope 14 to the bulb clip member 50 thereby. With the lamp envelope 14 secured to the alternate bulb clip member 50, the envelope and clip arrangement 14, 50 is secured to the lamp base 12 in a similar manner as discussed relative to the bulb clip arrangement of Fig. 2. The alternate bulb clip member 50 fits just under the lip portion 12a of the lamp base 12 and further, is prevented from dislocating to a downward position within the lamp base 12 by the sizing of the annular ring 52 which is larger than the inside diameter of the lamp base 12 at that region just below the lip portion 12a of the lamp base 12. Also as previously discussed, the selection of four as the number of extension arms 52 is considered to be a design choice that could be modified without departing from the inventive concept embodied in the present invention. As seen in Figures 5 and 6, two other alternate bulb clip arrangements 60 and 70 are shown. In each of these embodiments, a central annular ring portion 62, 72 is provided and first and second sets of extension arms are provided extending from each of the respective annular rings 62, 72. In Fig. 5, the first set of extension arms 64 extend downward and are effective for clamping the bulb clip 60 to the lamp envelope 14. The second set of extension arms 66 clamp the bulb clip 60 and lamp envelope assembly to the lamp base 12.

Similarly, the bulb clip 70 of Fig. 6 has a first set of extension arms 74 which clamp the bulb clip to the lamp envelop 14 and a second set of extension arms, extending outward from the annular ring portion 72 for clamping the bulb clip 70 and lamp envelope 14 to the lamp base 12.

Although the hereinabove described embodiments constitute preferred embodiments of the invention, it should be understood that further modifications can be made thereto without departing from the scope of the invention as set forth in the appended claims.

Claims

C L A I M S

1. A mounting arrangement for an electrodeless discharge lamp which provides mounting of a lamp envelope to a lamp base, said mounting arrangement comprising: a mounting member having a center support portion and a plurality of arms extending outwardly therefrom; wherein each of said plurality of arms has at least one curved portion; wherein -one curved portion of said plurality of arms contacts a ridge formed on an inner surface of said lamp base thereby securing said mounting member to said lamp base; and, wherein a second portion of said plurality of arms contacts an indention portion formed at the end of the lamp envelope which extends into said lamp base, said second portion of said plurality of arms thereby securing said lamp envelope to said mounting member which in turn has been secured to said lamp base by said curved portion of said plurality of arms.

2. An electrodeless discharge lamp mounting arrangement as set forth in claim 1 wherein said curved portion and said second portion of each of said plurality of arms extend in opposite directions so that when a pulling force is exerted on said lamp envelope, said curved portion exerts a greater force on said ridge formed in said lamp base and thereby causes said second portion of said plurality of arms to exert a greater contacting force on said indentions formed in said lamp envelope.

3. An electrodeless discharge lamp mounting arrangement as set forth in claim 1 wherein said mounting member has a center opening formed therein through which a coil member associated with a ballast circuit disposed in said lamp base extends.

4. An electrodeless discharge lamp mounting arrangement as set forth in claim 1 wherein at least one extrusion portion is formed in said indention portion of said lamp envelope so as to contact side portions of a pair of said plurality of arms thereby preventing rotational movement of said lamp envelope relative to said mounting member.

5. An electrodeless discharge lamp mounting arrangement as set forth in claim 4 wherein an extension is formed in the region of said ridge formed on said inner surface of said lamp base, said extension contacting an end portion of at least one of said plurality of arms and being effective so as to prevent rotational movement of said mounting member relative to said lamp base thereby.

6. An electrodeless discharge lamp mounting arrangement as set forth in claim 1 wherein said plurality of arms are spaced substantially equidistant around the circumference of said center support portion.

7. An electrodeless discharge lamp mounting arrangement as set forth in claim 1 wherein an outer lip portion is formed on said lamp base in an extending manner above said ridge on which said mounting member is secured, said outer lip portion having a sealing member disposed thereon such that said lamp envelope contacts said sealing member when said lamp envelope has been mounted onto said lamp base.

8. A mounting arrangement for an electrodeless discharge lamp which allows mounting of a lamp envelope to a lamp base, said mounting arrangement comprising: a mounting member having a ring portion and a plurality of arms extending therefrom; wherein each of said plurality of arms has at least one curved portion extending therefrom; wherein said ring portion of said mounting member contacts an annular ridge formed on the inner surface of said lamp base thereby securing said mounting member to said lamp base; and wherein a first one of said at least one curved portion of said plurality of arms contacts an indention portion formed at the end of the lamp envelope which extends into said lamp base, said first curved portion of said plurality of arms thereby securing said lamp envelope to said mounting member which in turn has been secured to said lamp base by said ring portion contacting said annular ridge formed on said lamp base.

9. An electrodeless discharge lamp mounting arrangement as set forth in claim 1 wherein at least one extrusion portion is formed in said indention portion of said lamp envelope so as to contact side portions of a pair of said plurality of arms thereby preventing rotational movement of said lamp envelope relative to said mounting member.

10. An electrodeless discharge lamp mounting arrangement as set forth in claim 9 wherein an extension is formed in the region of said ridge formed on said inner surface of said lamp base, said extension contacting an end portion of at least one of said plurality of arms and being effective so as to prevent rotational movement of said mounting member relative to said lamp base thereby.

11. An electrodeless discharge lamp mounting arrangement as set forth in claim 8 wherein said plurality of arms are spaced substantially equidistant around the circumference of said center support portion.

12. An electrodeless discharge lamp mounting arrangement as set forth in claim 8 wherein an outer lip portion is formed on said lamp base in an extending manner above said ridge on which said mounting member is secured, said outer lip portion having a sealing member disposed thereon such that said lamp envelope contacts said sealing member when said lamp envelope has been mounted onto said lamp base.