US 2937308 A
Description (OCR text may contain errors)
May 17, 1960 D. A. HOWLES ETA!- 2,937,303
ELECTRIC LAMPS Filed Sept. 5, 1956 2 Sheets-Sheet 1 IN VE/V TORS DOA/4L D H THUR H0 W450 .%:H5r THOM WRIGHT ATTORNEY May 17, 1960 D. HOWLES ET 2,937,308
' ELECTRIC LAMPS Filed Sept. 5, 1956 2 Sheets-Sheet 2 lNl/FN TORS DON 7L0 RR THUR H0 WL E6 JOHN WILLOUGHSXWPI6H a r 7OFPNE f United States Patent 2,937,308 ELECTRIC LAMPS Donald Arthur 'Howles and John Willoughby Thomas Wright, Leicester, England,- assignors to The British Thomson-Houston Company Limited, London, England,aBritish company w d Application September 5, 1956, Serial No. 608,019
(Claims riority application Great Britain p September 7, 1955 Y '4 Claims. (Cl. 313-315) ,This invention relates to electric lamps and is herein described with particular reference to the smaller orminiature types of incandescent lamp such as those used on automobiles or cycles in which the filaments occupy adefinite position in the bulb. Such lamps are usually made by the butt-seal method in which an exhaust tube is sealedto the neck of the bulb and the leading-in wires are sealed through the sides of the neck at the glass joint made between the exhaust tube" and the bulb.
After sealing and exhausting operations have been completed the lamps heretofore have been provided with ametal cap which is attached to the neck of the bulb by means of a cement or plaster. This method of manufacture has the disadvantage that owing to the'nature of the sealing operation it is diiiicult to control the location of the filament in the. bulb and even if the filament is posi- 2,937,308 Patented May 1960 lead-in wires 2 maintained in spaced apart relationship by a vitreous bead 3. The wire from which the lead wires 2 are formedis compatible with the glass of the bulb 1 and the'vitreous bead 3, that is, their relative coefficients of thermal expansion are matched to a considerable degree. In the manufacture of the lamp illustrated, the filament'mount, including the lead wires 2 having U- shaped end parts, and an exhaust tube 6 are introduced into the neck portion of the bulb prior to the pinching operation for the formation of the two-wing pinch 4.
v To prevent closure of the upperend of the exhaust tube 6 during the pinching operation, we provide the tube with means represented by the shaded portion in Fig. 1 which may consist of a thin metal sleeve, a thin rod of porous material (elg. asbestos or carbon) or a zirconium dioxide powder coating. During the pinching operation the neck portion of the glass bulb 1 is formed into the flattened two-winged pinch 4 and the U-shaped end parts of the leadwires 2 are sealed through the wings of the pinch so that a pair of loops project from the bottom faces of the wings, thelead wires 2 emerging from the respective tioned correctly within the bulb, loose or faulty capping may result in the-filament being incorrectly positioned relative to the axis of the cap.
' As lamps of this type are frequently used'with a reflector it is most important that the filament should occupy a definite position with respect to any reflector employed with the lamp and that the base of the lamp should be firmly and securely housed in its holder.
According to our inventionwe obviate the above disadvantage by providing a lamp which is capless and in which ,the mount structure is correctly located prior'to the'sealing operation and held firmly in that position during the time't hat the exhaust tube is being sealed'at the neck-of th'ebiilb. To this-end our invention consists ,in' electricda'mp comprising a glass bulb, a flattened glass pinch sealed to close 'the bulb; the lead wires being wings of the pinch 4-at 8 and re-entering the wings 4 at gage these notches to hold the lamp in position. These notches 7, instead of occupying the positions as shown may be-formed' at positions approximately midway between theroot of the bulb 1 and the bottom of the pinch 4. It then becomes convenient to depress the tips of the lamp contacts 5 into the notches. As an alternative to the notches 7, the pinch 4 could be formed with pro-' tuberances'which are engageable by the spring contactmaking members of a spring clip holder for locating and retaining the lamp in the'holder. v
The double filament embodiments of the invention 4 shown inFig-ures 3 to 11 inclusive follow the general patbroughtthroughthe seal, looped and returned into the seal; the-loopportions of each "lead wire being flattened down on to the pinch. 'As'a further feature of the invention location-of an incandescent lamp according to the invention in asuitable holder is facilitated by holding on to the pinch which is suitably shaped for the purpose,
and to assist in determining the light centre length and locking within the holder the shaping may include suitably,
shaped and disposed notches, grooves or protuberances.
The invention may be better understood from the following description read with the accompanying drawings, in which Figures 1 and 2 show two views of a single filament lamp constructed in accordance with the present invention, and Figures 3, 4 and 5 show three views of a lamp similar in all respects to that shown in Figures 1 v and 2 except that it has two filaments disposed side-byside in the plane of the pinch.
Figures 6, 7 and 8 show three views of another double 1 filament capless lamp formed similarly with a straight ternof the single filament embodiment shown by and described with reference to Figures 1 and 2. For this reason itfis convenient to'refer to like parts by like reference numerals) Thethree double filament embodiments are illustrated by w'ay -of example as being lamps each employing bow filaments of the same -L.'C.L. (light center length). It will be appreciated, however, thatthe filaments may be of any desired-form, e.g.' one filament could be'of V formation transversely-disposed with reference to an associated bow filament having a ditferent L.C.L.
In-Figures 3 and 4, the two bow filaments are mounted sidejby side in the plane of the two-wing pinch 4 while the lainp contacts 5 are arranged on both wings of the pinch with the contacts appertaining to a particular filament being located on the same wing.
Whilelthe pinch is again a flattened two-winged one in the embodiment illustrated by Figures 6, 7, and 8, and the lamp contacts 5 appertaining to a particular filament are arranged on the same wing of the pinch 4, the filaments are arranged side by side so that one of the filaments lies in the plane of the pinch 4 while the other is offset therefrom.
Figures .9 to 11 illustrate a further double filament embodiment of the invention having a cruciform or fourwing'glass pinch whereby considerable physical stability of the lamp is achieved when. the pinch is located in a,
suitable holder. The illustrated position of the filaments is purely exemplary since it is obvious that either or both pairs of lead wires 2 could be bent to give any required disposition of the filaments within the bulb 1.
Anyof the lamps described above could have portions of their contacts 5 flattened if desired, thereby further increasing the surface area of the contacts engageable by the contacts of a suitable holder.
In each of the illustrated embodiments the lead wires 2 emerge from the wings of the pinch 4 at 8 and re-enter these wings at points 9 spaced from the points of emergence 8, thereby anchoring both ends of the lamp contacts 5 in the body of the pinches 4.
While the invention has been particularly described with reference to incandescent lamps it will be obvious to those skilled in the art that insofar as the invention is directed to a specific form of pinch and contact combination the invention in its broadest aspect is not to be limited by any other features that may necessarily form part of a commercial product. For instance, the fila ment may be replaced by an electrode assembly where an indicator lamp of the gas-filled glow discharge type is required. Likewise while we have described an incandescent lamp of which the filament assembly includes a vitreous bead itwill be obvious that the invention is not to be limited. thereto although the use of a head is preferred particularly where such lamps are intended for use under vibration conditions and where one or more extra filament supports are required.
The design and manufacture of the lamp according to the present invention offers several advantages among which are a shorter overall length for a given bulb size, and lower cost due to a reduction in the number of parts and steps in the process of making a complete lamp and no two-part lead.
It will be also appreciated by those skilled in the art that although the contact wires are shown located one on each side of the pinch they could be spaced in any other practical position and that by using a properly designed mount and bulb a lamp of prefocused design could be made.
What we claim is:
1. A capless electric lamp comprising a glass bulb, an external substantially solid flattened plural-winged glass pinch sealed to close said bulb and providing plane surfaces extending parallel to the axis of said lamp for 10: cating the lamp in a suitable holder, and a plurality of lead wires which emerge from said pinch after passing therethrou-gh from within said bulb and re-enter said pinch atpoints spaced from their points of emergence, the external parts of the lead-wires being in the form of flat free loops bent back against said plane surfaces of said pinch wings to provide lamp contacts whereby the substantially solid pinch provides a mechanically strong abutmentfor said contacts.
- -;2;. A ca'pless electric lamp comprising a glass bulb, an external substantially solid flattened two-winged glass pinch sealed to close said bulb and providing plane surfaces extending parallel, to the axis of said lamp for 10- cating the lamp in a suitable holder, and a plurality of lead wires which emerge from the wings of said pinch after passing therethroughfiroiri within the bulb and reenter said wings at points spaced from. their points of emergence, the external parts of the lead wires being in the form of flat free loops bent back against said' plane surfaces of said wings to provide lamp contacts whereby the substantially solid pinch provides a mechanically strong abutment for said contacts.
3. 'A capless electric lamp comprising a glas's bulb, an external substantially solid flattened two winged glass pinch sealed to close said bulb and providing plane surfaces extending parallel to the lamp axis for locating the lamp in a suitable holder, and two lead wires which emerge respectively from the wings of said pinch after passing therethrough from within the bulb and re-enter the same wings at points spaced 'from their points of emergence, the external parts of the lead wires being in the form of fiat free loops bent back against the plane surfaces of said wings to provide lamp contacts whereby the substantially solid pinch provides a mechanically strong abutment for said contacts. m
4. A capless electric lamp comprising a glass-bulb, an
1 external substantially solid flattened four-winged glass pinch sealed to close the bulb and providing plane surfaces extending .parallel to the axis of the lamp forlocating the lamp in a suitable holder, and a pair or filaments arranged within said bulb, and four lead wires connecting in pairs to the respective filaments and which emerge from different wings of said pinch after passing 1 therethrough from within said bulb and re-enter the, same wings at points spaced from their points of emergence, the external parts of the lead wires being in the form of flat free loops bent back against the plane surfaces of said wings to provide lamp contacts whereby the substantially solid pinch provides a mechanically strong abutment for said contacts.
References Cited in the file of this patent [UNITED STATES PATENTS Westra Nov. 18, 1958