Fluorescent lamp and method for attaching a base member to an end of same

Information

  • Patent Grant
  • 6794811
  • Patent Number
    6,794,811
  • Date Filed
    Friday, February 15, 2002
    22 years ago
  • Date Issued
    Tuesday, September 21, 2004
    19 years ago
Abstract
A fluorescent lamp includes a glass envelope having a sealed end portion, a base shell member of a cup-shape configuration adapted to engage the envelope end portion, and a collar of shrink wrap material disposed around the envelope end portion and sides of the base shell member, the shrink wrap material being shrunken and compressing against the envelope end portion and the base shell member, to fix the base shell member on the envelope end portion.
Description




BACKGROUND OF THE INVENTION




1. Field of the Invention




The invention relates to fluorescent lamps, and is directed more particularly to a base for such lamps.




2. Description of the Prior Art




In the manufacture of lamps, a lamp envelope is usually provided with at least one base. Generally, a lamp base comprises a rigid shell secured to an end portion of the lamp envelope. At least one insulating disk is fixed in the shell for carrying one or more hollow base pins, or contacts, into which the lamp lead wires are electrically secured. The lamp is supported by one or more holders, or sockets, into which the lamp bases extend for communication with a source of electrical energy.




Typically, such lamp bases are secured to the end portions of the lamp envelope by means of a cement which is applied to the inside surface of a base shell annular wall. A sufficient quantity of cement is used to fill a gap between a lamp seal and the annular wall of the base. During manufacturing, each base is first fitted loosely onto a respective end portion of the lamp envelope. Thereafter, the cement is cured, as by heating, which allows the base to adhere to the lamp bulb and withstand industry torque requirements.




While the above technique of securing the lamp base by means of a suitable cement has been employed successfully in many lamp families, including fluorescent, it has been found that certain disadvantages exist. For example, the cement not only adds cost to the lamp but also requires the need for a separate process of applying the raw cement to the base shell. Moreover, while present manufacturing facilities using such a technique are equipped with machines which dispense cement, the machines require constant monitoring and periodic mechanical and electrical maintenance. Another disadvantage is the curing process of the cement, wherein indirect natural gas flame heat is used to cure the basing cement after the base is fitted to the end of the lamp. The temperatures required to cure the cement sometimes cause damage in the seal area of the lamp envelope. In addition, the machinery needed to provide the heat for curing not only requires periodic maintenance but also takes up valuable floor space in the production line.




Various alternatives for securing the base to the lamp end with little or no cement, or other type of adhesive, have been proposed in the past. For example, U.S. Pat. No. 2,993,191, which issued on Jul. 18, 1961 to Pietzsch et al, discloses a base for an electric discharge lamp wherein the base is constructed from resin having a modulus of elasticity which is greater than 5,000 kg./cm.


2


and as high as about 19,000 kg./cm.


2


. The resin has a breaking dilation of more than 50% and as high as about 230% and has an initial softening temperature of as low as about 150° Celsius and as high as about 210° Celsius. In one embodiment, the base of Pietzsch et al is positioned with the annular wall adjacent to the trough of a bulb end which has been heated to about 330° to 350° Celsius. As a result, the base material melts and occupies the trough or channel and, by reason of the character of the material of which the base is composed, adheres to the surface of the glass bulb. Alternatively, the base may be pressed against the bulb end to cause an annular rib or reinforcement to snap over the bead or rim and into a trough or channel of the bulb without heating the bulb neck.




U.S. Pat. No. 4,221,453, which issued to Wagener on Sep. 9, 1980, discloses a base for a fluorescent lamp. The base comprises a frontal portion, contact pins electrically connected to the connecting wires, at least one drop of glue which dries at room temperature, and an annular wall extending circumferentially from and perpendicular to the frontal portion. The annular wall has at least two equally circumferentially spaced knobs protruding inwardly. The base is formed from an elastic, bendable thermoplastic material so that when the base is fitted to the tube over the end portion, the annular wall elastically deforms and the knobs slide over the collar and snap into the groove of the lamp end portion. To safeguard against rotary movement of the base relative to the bulb, the base is formed with radial ribs to be disposed in notches provided in the bulb neck.




U.S. Pat. No. 5,432,400, which issued Jul. 11, 1995 to Spaulding et al, discloses a lamp including a glass envelope having a base fitted at each end portion thereof. Each lamp base includes a metallic base shell having an annular flange. The annular flange is heated prior to fitting over the end portion of the envelope so as to increase the inner flange diameter. Cooling of the annular flange after fitting reduces the flange diameter, thereby providing an interference fit with the end portion. The lamp base is retained on the end portion without the need for basing cement. In order to accommodate variations in the diameter of the lamp seals, an annular rib is formed on the inner surface of the flange. After cooling, the annular rib forms an interference fit with the lamp end portion.




While the bases described in the above patents appear to be satisfactory from a functional standpoint, it is believed that unanticipated production and/or other related problems, as well as material cost, may explain why such bases have not been commercially successful. Accordingly, it is deemed advantageous to provide another viable alternative.




SUMMARY OF THE INVENTION




An object of the invention is, therefore, to provide a fluorescent lamp in which each base is fixed to a lamp envelope end in a manner requiring little machinery, reduced time, and greatly reduced costs.




A further object of the invention is to provide a method for attaching a base member to an end of a lamp envelope, which method is relatively simple and easily accomplished with little machinery, and reduced time and costs.




With the above and other objects in view, as will hereinafter appear, a feature of the present invention is the provision of a fluorescent lamp comprising a glass envelope having an end portion, and a base shell member of a cup-shape configuration adapted to engage the envelope end portion. A collar of shrink wrap material is disposed around the envelope end portion and sides of the base shell member, the shrink wrap material being shrunken and compressing against the envelope end portion and the base shell member, to fix the base shell member on the envelope end portion.




In accordance with a further feature of the invention, there is provided a method for attaching a base member to an end of a fluorescent lamp glass envelope. The method comprises the steps of providing an annular end portion on a wall portion of the glass envelope, and pressing a base shell member of a cup-shape configuration onto the end portion of the envelope. Further steps include applying a collar of shrink wrap material to the envelope end portion and the base shell member, and shrinking the collar to compress against the envelope end portion and the base shell member, to fix the base shell member on the envelope end portion.




In accordance with a still further feature of the invention, there is provided a fluorescent lamp comprising a glass envelope having an end portion and a base shell member of a cup-shape configuration adapted to engage the envelope end portion. A collar of wrap material is disposed around the envelope end portion and sides of the base shell member, an adhesive is disposed on an interior surface of the collar, the adhesive being contiguous with the glass envelope end portion and the base shell member, to fix the base shell member on the envelope end portion.




In accordance with a still further feature of the invention, there is provided a method for attaching a base member to an end of a fluorescent lamp glass envelope, the method comprising the steps of providing an annular end portion on a wall portion of the glass envelope, pressing a base shell member of a cup-shape configuration onto the end portion of the envelope, and applying a collar of wrap material to the envelope end portion and the base shell member, the wrap material having an adhesive on an interior surface of the collar, to fix the base shell member on the envelope end portion.




The above and other features of the invention, including various novel details of construction and combinations of parts and method steps will now be more particularly described with reference to the accompanying drawings and pointed out in the claims. It will be understood that the particular devices and method steps embodying the invention are shown by way of illustration only and not as limitations of the invention. The principles and features of this invention may be employed in various and numerous embodiments without departing from the scope of the invention.











BRIEF DESCRIPTION OF THE DRAWINGS




Reference is made to the accompanying drawings in which is shown an illustrative embodiment of the invention, from which its novel features and advantages will be apparent.




In the drawings:





FIG. 1

is a side elevational, partly sectional, view of an end portion of a fluorescent lamp, showing one form of base member attachment to the lamp envelope, illustrative of an embodiment of the invention;





FIG. 2

is similar to

FIG. 1

, but illustrative of an alternative embodiment;





FIGS. 3 and 4

are exploded perspective views of the components of the base member attachment means of

FIGS. 1 and 2

; and





FIG. 5

is a perspective view of the assembled components of the base members attachment means of

FIGS. 1-4

.











DESCRIPTION OF THE PREFERRED EMBODIMENTS




Referring to

FIG. 1

, it will be seen that a fluorescent lamp


10


comprising a tubular vitreous or glass envelope


12


is provided with an inner coating of phosphor


14


and is hermetically sealed at each end by a glass mount


16


. Each mount


16


includes a stem press


18


within which a pair of lead wires


20


are sealed. A thermionic electrode


22


is mounted on the inner ends of lead wires


20


within the tubular glass envelope


12


. Each thermionic electrode


22


comprises a tungsten coil coated with an emissive material of alkaline earth oxides.




In accordance with standard lamp-making practices, the envelope


12


is filled with a suitable starting gas and doped with mercury to provide an ionizable medium within the sealed envelope, which permits an electric discharge to pass between the thermionic electrodes.




Each end portion


24


of the lamp envelope


12


may include an annular groove


34


which terminates at an annular rim or seal


38


. Each of the sealed end portions


24


of envelope


12


is fitted with a base


30


that includes a pair of axially-extending metal base pins


32


, or other form of contacts, which serve as terminals for the lamp


10


and are adapted, by virtue of their spacing and dimensions, to permit the lamp to be inserted into the socket components of a lighting fixture and be operated from a suitable electrical power supply. Each lead wire


20


extends through the stem press


18


in mount


16


to a respective metal base pin


32


.




Base


30


includes a metallic base shell


42


having an annular flange


44


. When the base


30


is secured to the lamp end portion in a manner to be described below, an inner surface


40


of the annular flange


44


contacts the lamp end portion


24


and when the end portion includes the seal


38


, contacts the annular seal


38


. Base shell


42


is formed of a suitable metal, such as aluminum. The base shell


42


may be provided with an inwardly-directed annular ridge (not shown) for engaging the groove


34


.




A disk


46


of insulating material is secured to base shell


42


. The base pins


32


are received in registering apertures formed in the insulating disk


46


. Each of the base pins


32


is provided with a flange portion


48


engaging the lower surface of disk


46


, the base pin inner ends being swaged or riveted into contact with the upper surface of disk


46


, thus rigidly securing the pins in position.




While the base


30


is shown including two base pins, any number of pins may be used depending upon the type of lamp. While only one insulator disk is used in the base illustrated, each base pin may be mounted on separate insulating disks.




To secure the base shell


42


to the envelope


12


, the base shell member


42


is pressed onto the end portion


24


of the envelope


12


. A collar


60


of shrink wrap material is fitted around the annular end portion


24


of the envelope


12


, and around the flange


44


of the base shell member


42


. The collar


60


is shrunken, as by the application of heat, to compress against the envelope end portion


24


, and the base shell member flange


44


, to urge the shell member flange


44


against envelope end portion


24


, including the seal


38


, if present, to fix the base shell member


42


on the envelope end portion


24


.




Alternatively, or in combination with the above, the collar


60


may be provided with a layer of adhesive


62


(

FIG. 2

) on an interior surface


64


thereof. In this embodiment, the collar


60


is adhered to the glass envelope end portion


24


and the base member flange portion


44


, with which the adhesive


62


is contiguous, to fix the base shell member


42


on the envelope end portion


24


. The adhesive


62


may be heat curable, in which case the adhesive is cured by the application of hot air, or the like, to bond with the envelope end portion


24


and the base shell flange


44


to fix the shell member


42


on the glass envelope end portion


24


.




There is thus provided a fluorescent lamp in which a base member is fixed to a lamp envelope end portion in a manner and by way of a method requiring little machinery, and reduced time and costs relative to prior methods.




It will be understood that many additional changes in the details, materials, steps and arrangement of parts, which have been herein described and illustrated in order to explain the nature of the invention, may be made by those skilled in the art within the principles and scope of the invention as expressed in the appended claims.



Claims
  • 1. A fluorescent lamp comprising:a glass envelope having a sealed end portion; a base shell member of a cup-shape configuration adapted to engage the envelope end portion; a collar of shrink wrap material disposed around the envelope end portion and sides of the base shell member, the shrink wrap material being shrunken and compressing against the envelope end portion and the base shell member, and an adhesive disposed on an interior surface of said collar and continuous with the glass envelope end portion and said base shell member, to fix the base shell member on the envelope end portion.
  • 2. The lamp in accordance with claim 1 and further comprising insulating means secured to said base shell member.
  • 3. The lamp in accordance with claim 2 wherein said base shell member is of metal.
  • 4. The lamp in accordance with claim 1 wherein said adhesive is curable adhesive.
  • 5. The lamp in accordance with claim 4 wherein the shrink wrap material is heat shrunk and said adhesive is heat cured.
  • 6. The lamp in accordance with claim 1 wherein the shrink wrap material is heat shrunk.
  • 7. A fluorescent lamp comprising:a glass envelope having a sealed end portion; a base shell member of a cup-shape configuration adapted to engage the envelope end portion; a collar of wrap material disposed around the envelope end portion and sides of the base shell member; and an adhesive disposed on an interior surface of said collar and contiguous with the glass envelope end portion and said base shell member, to fix said base shell member on the envelope end portion.
  • 8. The lamp in accordance with claim 7 and further comprising insulating means secured to said base shell member.
  • 9. The lamp in accordance with claim 8 wherein said base shell member is of metal.
  • 10. The lamp in accordance with claim 7 wherein said adhesive is cured adhesive.
  • 11. The lamp in accordance with claim 10 wherein said adhesive is heat curable and said collar is of shrink wrap material which is heat shrinkable.
  • 12. The lamp in accordance with claim 7 wherein said collar is of a shrink wrap material and is shrunken on the glass envelope end portion and said base shell member.
US Referenced Citations (7)
Number Name Date Kind
2993191 Pietzsch Jul 1961 A
4221453 Wagener Sep 1980 A
4990821 Blaisdell et al. Feb 1991 A
5432400 Spaulding et al. Jul 1995 A
5747551 Lewandowski et al. May 1998 A
6078136 Sica Jun 2000 A
6517243 Huffer et al. Feb 2003 B2