EP0381269A1

EP0381269A1 - Electric lamp

Info

Publication number: EP0381269A1
Application number: EP19900200179
Authority: EP
Inventors: Livio Borgis; Cornelis Penning
Original assignee: Philips Gloeilampenfabrieken NV; Koninklijke Philips Electronics NV
Current assignee: Koninklijke Philips NV
Priority date: 1989-01-31
Filing date: 1990-01-25
Publication date: 1990-08-08
Also published as: HUT53470A; NL8902438A; CN1044736A; HU900378D0; JPH02234343A; HU203003B

Abstract

The electric lamp has a lamp vessel (1) with an end portion (3) and a plastic lamp cap (5) carrying electrical contacts (7, 8). The lamp cap (5) has a sheath portion (9) with an open end portion (11) and a base portion (12). The end portion (3) of the lamp vessel (1) is fixed in the open end portion (11) of the lamp cap (5) by cooperating cams (20) and grooves (10). The lamp cap (5) has an axial separation surface (15) and a first (16) and a second part (17) arranged laterally thereof, which are rigidly connected to each other.

Description

The invention relates to an electric lamp provided with
a translucent lamp vessel with an axis and an end portion on said axis,
an electric element in the lamp vessel,
a plastic lamp cap with an axis, which carries electrical contacts and is fixed around said end portion of the lamp vessel, and which has a sheath portion with an open end portion surrounding said end portion of the lamp vessel and a base portion opposite to the open end portion, which base portion carries at least one of the contacts,
current supply conductors which extend from the electric element to the contacts of the lamp cap,
the lamp cap and the lamp vessel having cooperating cams and grooves, which limit a relative rotation and translation of the lamp cap.
Such a lamp is known from GB 1,210,346.
The lamp cap of the known lamp is a Swan (bayonet) lamp cap, with which a lampholder makes electrical contact at two discrete points on the base portion. In this known lamp, the lamp cap has axial slots at the open end portion to make the lamp cap flexible at said end portion so that the lamp cap, when it is assembled with the lamp vessel, can become wider at its open end portion in order that the cams and grooves can be brought into engagement with each other.
A disadvantage of this known lamp is that the lamp cap of a finished lamp can again become wider due to its flexibility when forces are exerted on it and that the coupling between the lamp cap and the lamp vessel can then be lost. In order to obviate this disadvantage, the slots are closed, for example by means of glue or cement, after the assembling operation. This has the disadvantage that the use of, for example, cement, which must be cured in order to secure the lamp cap to the lamp vessel, is not avoided.
Another plastic lamp cap of the Swan type is known from GB 2,152,746A. This lamp cap also has slots at the open end portion or is thermally deformed after being arranged on the end portion of a lamp cap so as to form cams which are in engagement with grooves in the lamp vessel.
GB 1,380,720 discloses an electric lamp having a plastic lamp cap of the Swan type in which the lamp cap is glued to the lamp vessel. The lamp has no means to make it resistant to torsional forces exerted on the coupling between the lamp cap and the lamp vessel. The known lamp has no essential advantages in comparison with a lamp having a lamp cap secured by means of cement.
The invention has for its object to provide an electric lamp of the kind described in the opening paragraph, which has a lamp cap having a construction which permits among others an easy assembly of the lamp cap and the lamp vessel and is further suitable to be formed as an Edison lamp cap, in which in fact an electrical contact is made in a lampholder at an arbitrary point along the periphery of the lamp cap near its base portion.
This object is achieved in a lamp of the kind described in the opening paragraph in that the lamp cap has an axial separation surface and first and second parts arranged laterally of said separation surface, which parts are rigidly connected to each other.
This construction has great advantages, both in Swan and in Edison lamp caps, i.e. amongst others a rapid assembly, a good coupling between lamp vessel and lamp cap, and the possibility of providing a defined path through the lamp cap for the current supply conductors.
The parts of the lamp cap may be connected to each other through means integral therewith, for example by mechanical means like a snap connection. Thus, for example, cooperating cams can be present at the first and second part of the lamp cap. Very favourable also is an embodiment which has projections and recesses, in which each time one projection at a part of the lamp cap is arranged with clamping fit in a recess in another part of the lamp cap. In one embodiment a recess has a part of reduced width, through which a projection is passed. Mostly, the presence of such a part of reduced width results in that the recess opens out into the outer surface of the lamp cap.
The coupling of one lamp cap part to the other, and thus the coupling of the lamp cap to the lamp vessel, is particularly tight if a snap connection is present at the open end portion of the lamp cap. This is favourable for lamp caps having a comparatively large diameter, for example 20 mm or more, in which case higher requirements are set for the minimum torsional force which the lamp cap must be able to withstand without losing its coupling to the lamp vessel than in the case of lamp caps having a smaller diameter.
A snap connection, for example a snap connection in the open end portion, may be combined with connection means of a different kind elsewhere at the lamp cap, for example mutually cooperating projections and recesses.
Due to the fact that the lamp cap is axially divided, the current supply conductors can readily be passed from the lamp cap to the exterior, i.e. along the axial separation surface. The comparatively slack current supply wires then need no longer be threaded through narrow openings in the lamp cap.
An important further consequence of the axial division of the lamp cap is that a very satisfactory coupling between the lamp cap and the lamp vessel is obtained so that the lamp cap and the lamp vessel are very satisfactorily locked against rotation and translation with respect to each other. Owing to the axial division, elasticity of the lamp cap is not necessary for coupling the lamp cap and the lamp vessel to each other. The cooperating cams and grooves present on the lamp vessel and the lamp cap, consequently, can be high and deep, respectively. During the assembling operation the parts of the lamp cap are in fact moved diametrically towards each other with the interposition of the lamp vessel.
In a favourable embodiment, the lamp vessel and the lamp cap have cooperating transverse grooves and cams for an axial coupling, so that the lamp vessel is externally unround at its end portion and the lamp cap is internally unround at its open end portion for locking against relative rotation.
The cams and the grooves may be so shaped that the end portion of the lamp vessel and the open end portion of the lamp cap have cooperating cross-sections which are in the form of a flattened ellipse whose major axis is at right angles to the separation surface. Torsional forces exerted by the lamp vessel on the lamp cap then form a smaller load for the coupling of the parts of the lamp cap.
In the end portion of the lamp cap, inwardly extending, for example tapering, projections may be present, for example prismatic ribs. These can compensate for dimensional differences, so that a coupling without play between the lamp vessel and the lamp cap can be obtained in spite of tolerances.
In a favourable embodiment, the lamp vessel has a first pair of mirror-imaged grooves and a second such pair facing the first pair. It is advantageous for the grooves to have boundaries which lie in a substantially axial plane of the lamp vessel. Owing to these boundaries, cams at the end portion of the lamp cap have a good grip of the lamp vessel in order to prevent relative rotation. It is favourable if these cams have an engagement surface which lies in a substantially axial plane of the lamp cap.
In another version of this embodiment each cam is connected to the lamp cap via an elastic arm. This version can be realized by surrounding each cam with a U-shaped split in the lamp cap. In this version a rattle-free coupling between the lamp cap and the lamp vessel can be obtained, irrespective of dimensional tolerances. The division of the lamp cap leads to the advantage that the cams can be made to engage with the grooves without having to be bent further outwards to that end than they would be, possibly, in their final position.
A contact may be formed at the base portion of the lamp cap around a current supply conductor, for example by means of solder. In a favourable embodiment, however, the lamp cap has on the separation surface at the base portion an axially directed cam, through which a current supply conductor emerges, said current supply conductor being bent backwards around said cam, while a metal tube, for example of brass or bronze, grips with clamping fit around said cam and said supply conductor to form an electrical contact.
This contact has the advantage that no welding or soldering operation is required and further that cold flow of the contact during the use of the lamp, which occurs with soldered contacts, is prevented. The metal tube may be provided with protruding tongues which enter the base portion of the lamp cap. As a result, the tube is additionally locked against rotation with respect to the lamp cap.
The axially directed cam at the base portion of the lamp cap may be recessed into the surface of the base portion so that the metal tube just projects from said surface. If the tube is closed on one side so as to be bush-shaped, a flat transverse contact surface is formed. Alternatively, the metal tube may extend at a comparatively great distance from the base portion to form a pin-shaped contact which may or may not be closed at its free end. The lamp cap may have two similar contacts at the base portion, such as two pin-shaped contacts in, for example, a fluorescent lamp or two contact surfaces in, for example, an incandescent lamp having a Swan-d lamp cap.
In another embodiment, a contact is formed at the base portion by means of a metal disk which comprises a perpendicularly flanged tongue, which is split so as to form a piercing contact. Piercing contacts are frequently used in technology for achieving electrical connections with conductors, which may or may not be insulated. In the case of insulated conductors, which can also be used in the lamp according to the invention, the piercing contact cuts through the insulation.
It is possible for the base portion of the lamp cap to comprise a duct-shaped recess, in which a current supply conductor is inserted when the lamp is assembled. The said recess can be intersected by a cavity for accommodating the split tongue of the contact. A contact applied centrally at the base portion may in this way be sufficiently fixed already. However, the contact may have a cylindrical rim, which can be inserted in a recess in the lamp cap for further fixation.
In an Edison lamp cap or a Swan-s lamp cap, in which cases in conventional metal lamp caps the sheath portion of the lamp cap makes electrical contact with a lamp holder at an arbitrary point along its periphery near the base portion, the lamp cap of the lamp according to the invention is formed in a favourable embodiment, for example, in the following manner. A current supply conductor emerges from the lamp cap near the periphery of the base portion and is bent backwards along the sheath portion of the lamp cap. A metal ring of U-shaped axial section engages the base portion and grips with clamping fit around the sheath portion of the lamp cap and around the current supply conductor. In a variation thereof, the sheath portion of the lamp cap has a continuous groove and the metal ring is additionally locked in that it is bent in said groove.
In another embodiment, a metal ring has the shape of an annular U-shaped duct. The lamp cap may have a circumferential groove near the periphery of the base portion, from which groove a current supply conductor emerges, which conductor is bent back along the sheath portion. The metal ring engages with the circumferential groove and grips around the sheath portion.
In a further embodiment, the lamp cap has a ring for making a second electrical contact with a lamp holder, which ring is provided with a split tongue connecting the ring with a current supply conductor by way of piercing contact. The ring may have a second tongue, which, like the piercing contact, is lodged in a cavity in the lamp cap and which provides an extra fixation for the ring. The ring may, however, be bent into recesses in the sheath portion of the lamp cap. The ring may have the form of a U-shaped annular duct, have a U-shaped cross-section, or it may have a different shape, for example conical, with or without a cylindrical outer rim.
In an Edison lamp cap, the sheath portion of the lamp cap has screw-thread; in a Swan lamp cap, the sheath portion is provided with radial projections for mechanical cooperation with a lamp holder.
An advantage of a lamp cap of synthetic material is that it is prevented that the lamp cap becomes welded to a lamp holder at the end of lamp life. This phenomenon may occur in a conventional incandescent lamp. When the filament breaks, a discharge arc may be produced in the lamp vessel. Due to the high current intensity of said arc, a fuse melts, which may be included in a current supply conductor. In the lamp cap, a discharge arc may then be produced, which may jump over to the metal sheath of the lamp cap and welds the said sheath to the lamp holder.
It is also possible that a discharge arc in one current supply conductor jumps over within the lamp cap to the other current supply conductor. The divided lamp cap of the lamp according to the invention permits of providing for each of the current supply conductors an individual path through the lamp cap closed from the other path and of thus preventing flash-over of a discharge arc within the lamp cap.
In conventional Edison lamp caps, in which the second contact is formed in that a current supply conductor is passed to the exterior at the open end of the lamp cap and is secured to the lamp cap, the distance of this securing point from the lamp vessel is considerably smaller than that of the contact at the base portion from the lamp vessel. Therefore, a portion must be cut from the first-mentioned current supply conductor in order to prevent that the free end of this conductor, which may be connected to mains voltage, extends along the lamp vessel and can be touched.
In the lamp according to the invention having an Edison or a Swan lamp cap, the difference between the distances of the contacts from the lamp vessel is small to begin with. In a favourable embodiment, the path for the current supply conductor to the contact at the cylindrical portion of the lamp cap has such a length that the distances of the contacts from the lamp vessel are substantially the same. The relevant current supply conductor then need not be shortened.
It is favourable if a part of the lamp cap has in the base portion a transversely directed groove at the separation surface and the other part of the lamp cap has a transversely directed cam at the separation surface, which cooperates with the groove and encloses a current supply conductor in said groove. The current supply conductor then emerges from the lamp cap at a defined point, which makes it easier to secure mechanically said conductor to a contact of the lamp cap. This cam and this groove also prevent that the bent portion of the conductor can become located between the two parts of the lamp cap and fails to establish a good connection with the contact of the lamp cap.
Electric lamps may also radiate light, albeit a small quantity, through the end portion of the lamp vessel. In some applications, for example in darkroom lamps, it may be a disadvantage if light from the end portion of the lamp vessel emerges along the axial separation surface of the lamp cap. In a particular embodiment, one part of the lamp cap has, at least at the open end portion, a rabbet which receives the other part. This makes the lamp cap impervious to light.
The electric lamp according to the invention may be, for example, an incandescent lamp, for example a halogen incandescent lamp, a low-pressure discharge lamp or a high-pressure discharge lamp. The kind of the electric element is in fact not essential to the invention. The electric element may be arranged in an inner envelope in the lamp vessel.
A disk-shaped prolongation of the open end portion of the lamp cap may extend from the said portion laterally of the lamp vessel, which prolongation is curved, for example parabolically or elliptically. The inner surface thereof may be mirror-coated to form a lamp/reflector unit.
It is favourable in a Swan lamp cap if the radial projections which have to cooperate with a lampholder are formed by metal pins anchored in the lamp cap. The projections may also consist of the ends of one continuous pin. It may then be recommendable that the pin(s) is (are) enveloped entirely with synthetic material within the lamp cap in order to prevent contact with current supply conductors.
A great variety of plastics may be used in the lamp cap, taking into consideration the temperature the lamp cap assumes during operation of an electric lamp of a given type. By way of examples, thermoplastic synthetic materials, such as polyether imide, polyether sulphone, polyether etherketone, for example with a basic structure as shown in Fig. 16, polybutylene terephthalate, polypropylene oxide, polyphenylene sulphide, polyamide imide and polyimide are mentioned.
Embodiments of the electric lamp according to the invention are shown in the drawing. In the drawing:

Fig. 1 is a side elevation of an electric lamp,
Fig. 2 is the elevation of the parts not yet assembled of the lamp cap of Fig. 1 taken on II,
Fig. 3 is a sectional view taken on III-III in Fig. 2,
Fig. 4 is a sectional view taken on IV-IV in Fig. 3,
Fig. 5 is the elevation of the separation surface of the lamp cap of Fig. 1 with contacts in sectional view,
Fig. 6 shows in side elevation, partly broken away, another embodiment of an electric lamp,
Fig. 7 shows a further embodiment of a lamp cap, represented as in Fig. 5,
Fig. 8 shows the elevation of the parts of the lamp cap taken on VIII in Fig. 7 after these parts have been made to face one another,
Fig. 9 shows an exploded view of a further embodiment of the lamp according to the invention,
Fig. 10 shows a cross-section through the lamp vessel of Fig. 9 taken on X-X,
Fig. 11 shows an elevation of contacts suitable for the lamp of Fig. 9,
Fig. 12 shows a sectional view taken on XII-XII in Fig. 11,
Fig. 13 shows an interior view of the parts of another embodiment of a lamp cap made of synthetic material, represented as in Figs. 5 and 7,
Fig. 14 shows cross-sections taken on XIV in Fig. 13, after the parts have been made to face one another, and
Fig. 16 shows the basic structure of a synthetic material used in the lamp cap, a linear aromatic polymer.

The electric lamp shown in Fig. 1 has a translucent lamp vessel 1 with an axis 2 and an end portion 3 on said axis. The lamp vessel 1 is blown, consists of glass and is sealed in a vacuum-tight manner. An electric element 4, i.e. a filament, is arranged in the lamp vessel 1. A plastic lamp cap 5, for example of polyether sulphone, has an axis 6, carries electrical contacts 7, 8 and is fixed around the end portion 3 of the lamp vessel 1. The lamp cap 5 has a sheath portion 9 with an open end portion 11 and a base portion 12 opposite to the open end portion 11. The base portion 12 carries a contact 8. Current supply conductors 13, 14 extend from the electric element 4 to the contacts 7, 8 of the lamp cap 5.
The lamp cap 5 and the lamp vessel 1 have cooperating cams 20 and grooves 10, which limit the relative rotation and translation of the lamp cap.
The lamp cap 5 has an axial separation surface 15 and a first 16 and a second part 17 arranged laterally of said separation surface 15, which parts 16, 17 are rigidly connected to each other. In the lamp cap shown, the means by which the parts 16, 17 are rigidly connected to each other are integral with these parts.
Fig. 2 shows the first part 16 and the second part 17 of the lamp cap 5, which are arranged opposite to each other before being assembled. The first part 16 has projections 18 and the second part 17 has recesses 19 (Fig. 4) as integral means by which the parts are coupled to each other.
Fig. 3 shows cams 20 at the parts 16 and 17 of the lamp cap 5, which engage into the grooves 10 of the lamp vessel 1.
In Fig. 4, the recesses 19 are shown, into which the projections 18 are passed. The recesses 19 have a portion 21 of reduced width, through which the projections are passed. In order that these portions 21 of reduced width can be realised, the recesses 19 extend as far as to the outer surface of the lamp cap.
Fig. 4 also shows that the cams 20 in the lamp cap 5 (Fig. 3) and the grooves 10 in the end portion 3 of the lamp vessel (Fig. 1) are formed so that the open end portion 11 of the lamp cap 5 has a cross-section in the form of a flattened ellipse, whose major axis 22 is at right angles to the separation surface 15. The end portion 3 of the lamp vessel 1 has a cooperating cross-section of complementary shape. The lamp cap 5 and the lamp vessel 1 are thus locked against relative rotation. Each of the two parts 16 and 17 of the lamp cap 5 in itself already strongly limits the relative rotation possibility of the lamp vessel 1. As a result, the coupling between the parts 16, 17 of the lamp cap 5 is loaded only very slightly in the longitudinal direction of the projections 18 when the lamp vessel 1 exerts a torsional force on the lamp cap 5.
Fig. 5 shows that the current supply conductors 13, 14 are passed to the exterior along the separation surface 15 of the lamp cap 5. When the lamp vessel is arranged in the first part 16 of the lamp cap 5, the current supply conductors 13, 14 are simply arranged over the base portion 12 of the lamp cap 5 so as to emerge from the lamp cap 5 after the second part 17 has been applied. The thin wires constituting the current supply conductors 13, 14 need not be threaded through narrow openings.
The lamp cap 5 has (Figs. 2, 3, 5) on the separation surface 15 at the base portion 12 an axially directed cam 23, through which a current supply conductor 14 is passed from the lamp cap 5 to the exterior, which conductor is bent backwards around the cam 23. A metal tube 8, shown in axial cross-section in Fig. 5, grips with clamping fit around said cam 23 and around said current supply conductor 14. It is visible in Fig. 5 that the cam 23 is recessed into the base portion 12 of the lamp cap 5. The tube 8 is closed in the Figure on one side to form a transverse contact surface. Protruding tongues 24 are provided at the tube 8, which engage into the base portion 12 and lock the tube 8 against relative rotation. Moreover, the tube 8 constitutes an additional coupling between the parts 16, 17 of the lamp cap 5 at the extreme end of the base portion 12, where there is little room for projections 18 and recesses 19 (Fig. 4), which already provide for a coupling between the parts 16, 17 of the lamp cap and hence between the lamp cap 5 and the lamp vessel 1.
The other current supply conductor 13 is passed to the exterior along the separation surface 15 of the lamp cap 5 near the periphery of the base portion 12 and is bent backwards along the sheath portion 9. A metal ring 7 of U-shaped axial section engages the base portion 12 and grips with clamping fit around the sheath portion 9 and around said current supply conductor 13. In Fig. 5, the sheath portion 9 has a circumferential groove 25, into which the ring 7 is bent. The ring 7 constitutes the side contact of the Edison lamp cap 5 shown. The ring 7 can make electrical contact with a lamp holder at any point on its periphery.
The lamp cap 5 is secured to the lamp vessel 1, the current supply conductors 13, 14 are secured to the contacts 7, 8 of the lamp cap 5 and these contacts are secured to the lamp cap in the lamp shown entirely by assembly. In this case, no use is made of thermal processes, such as cementing, glueing, soldering and welding, and of auxiliary materials, such as cement or glue.
In the embodiment shown (Figs. 2, 3, 5), the axially directed cam 23 on the separation surface 15 has a cooperating transversely directed cam 26 and a groove 27 in the second and first parts 17 and 16, respectively, of the lamp cap 5, the cam 26 and the groove 27 enclosing the current supply conductor 14 and causing said conductor to emerge at a defined point from the lamp cap 5.
The lamp cap 5 has near the periphery of the base portion 12 a transversely directed projection 28 on the separation surface 15 and a transversely directed recess 29 in the separation surface 15 at the second and first parts 17 and 16, respectively, of the lamp cap, which cause the current supply conductor 13 to emerge at a defined point from the lamp cap (Figs. 2, 3, 5). Moreover, this projection 28 and this recess 29 ensure that the current supply conductor 13 covers within the lamp cap 5 a path which has a transverse portion, as a result of which the length of the path within the lamp cap 5 is increased. Thus, it is achieved that the lengths of the paths of the two current supply conductors 13, 14 between the end portion 3 of the lamp cap and the contacts 7, 8 (Fig. 5) are substantially equal. With the use of equally long current supply conductors 13, 14 of the correct length, the conductor 13 need not be shortened.
The electric lamp shown in Fig. 6, in which identical parts have the same reference numerals as in the preceding Figs., has a lamp cap 55, in which an internally concave mirror-coated body 40 integral with the lamp cap 55 extends from the open end 11 along the lamp vessel 1. The first part 66 of the lamp cap 55 has a duct 41, in which the current supply conductor 13 is arranged. Otherwise, the first part 66 is identical to the first part 16 in Figs. 1 - 5. The second part 67, which, except for the concave mirror-coated part 40, is identical to the second part 17 in Figs. 1 - 5, entirely closes the duct 41. The duct 41 constitutes a closed path for the current supply conductor 13. As a result, no discharge arc can be produced in the cavity of the lamp cap 55 between the current supply conductors 13, 14.
An advantage of the lamp cap of the lamp according to the invention is that the end portion of a lamp vessel may have one given shape and dimension, independently of the kind of lamp cap which is to carry the lamp vessel, for example a B22 lamp cap or an E27 lamp cap. With the use of conventional lamp caps of these types, the lamp vessel must have at the end portion other dimensions with the use of a bayonet lamp cap of 22 mm diameter than with the use of an Edison lamp cap of 27 mm diameter. In the production of lamps, with the use of conventional lamp caps, this requires a conversion on the machines on which the lamp vessel is shaped at its end portion, even when lamps of the same power and operating voltage are concerned. B22 and E27 lamp caps of synthetic material may internally be dimensioned and shaped so that they fit onto one lamp vessel.
Instead of a blown lamp vessel, for example a bi-partite lamp vessel of pressed glass may be used in the lamp according to the invention.
Parts in Figs. 7 and 8 which correspond to parts in Figs. 1 - 5 have reference numerals which are 70 higher than those in Figs. 1 - 5. Cams 90 in these Figs., which cooperate with tangential grooves in the end portion of a lamp vessel, are formed by the walls of recesses 89, which are to accommodate projections 88, and by the envelopes of the extensions of these projections 88. Fig. 8 clearly shows the internally unround shape of the open end portion 81. The projections 88, 88′ and the recesses 89, 89′ cooperate in joining together the parts 86, 87 of the lamp cap 75. These parts 86, 87 are securely held together by the ring 77, shown in axial cross-section, near the base portion 82. The contact 78 also contributes to this.
The projections 88′ have a smaller diameter than the projections 88, which give a strong coupling to the open end portion 81. The projections 88′, therefore, have a less important function, the more so since a lateral displacement of the two parts 86, 87 along the separation surface 85 is also obstructed by a rabbet 100 and a rim 91 cooperating with it.
The first part 86 of the lamp cap 75, however, has the rabbet 100 with which engages a rim 91 of the second part 87 mainly with the object of making the lamp cap impervious to light.
The lamp cap has tapering projections 90′ in the open end portion 81, constituted by prismatic ribs in the Figure, which can compensate for dimensional differences with a lamp vessel. This lamp vessel is capable of deforming or partly breaking them away. The axially directed cam 93 has a cooperating transversely directed cam 96 and groove 97 on the separation surface 85, the cam 96 lying closer to the open end portion 81 than the cam 26 in Fig. 5. Farther removed from the open end portion 81, the groove 97 has two projections 97′. A current supply conductor is radially passed between these projections 97′ during assembly of the lamp cap 75 and held in the groove 97 by these projections until the second part 87 has been applied.
The base portion 82 of the lamp cap has a circular groove 99, in which a metal ring 77 with the shape of a annular, U-shaped duct can be accommodated and from which a current supply conductor 83 emerges, with which the ring makes an electrical connection. The groove may be provided with prismatic ribs which correspond to ribs 90′ in the open end portion 81.
Parts in Fig. 9 which correspond to parts in the Figs. 1 - 5 have reference numerals which are 100 higher than those in these Figs. In Fig. 9, the end portion 103 of the translucent lamp vessel 101, in which, for example, a pair of electrodes may be included as the electrical element, has grooves 110, 110′ (see also Fig. 10). The lamp cap 105 of synthetic material has a first 116 and a second 117 part on either side of the axial separation surface 115, each part being provided with cams 120 for cooperating with the grooves 110, 110′. The parts 116, 117 of the lamp cap 105 can be rigidly interconnected by means of snap connections 118, 119 at the open end portion 111. Projections 118′ and recesses 119′ contribute to the connection. The lamp cap 105 carries contacts 107 and 108.
Fig. 10 shows shapers S₁, S₂, each of which has made a pair of grooves 110, 110′ in the end portion 103 of the lamp vessel 101 (Fig. 9). Each pair of grooves 110, 110′ has a groove 110 which is the mirrored image of the other groove 110′. The pair of grooves 110, 110′ made by shaper S₁ in the Figure, moreover, is the mirrored image of the pair of grooves made by the other shaper S₂ opposite the first one. The grooves each have a boundary 110a, 110′a, which lies in a substantially axial plane of the lamp vessel 101. The grooves enable the cams of the same shape to get a good grip.
Fig. 11 shows a metal strip 201 which carries a contact 208 corresponding to the contact 108 from Fig. 9 and a contact 207 corresponding to contact 107, which contacts are suitable as contacts at the base portion and the sheath portion, respectively, of a lamp cap. They can be easily detached from one another and from the strip 201.
The tapering, ring-shaped contact 207 (see also Fig. 12) has a split tongue 210 (see also 107 in Fig. 9) acting as a piercing contact. When the ring 207 is detached from the strip 201, the tongue 210 is bent through 90°. The ring 207 has a cylindrical rim 212, which can be bent into recesses in a lamp cap for fixation. A connection tag 211 can also remain integral with the ring 207 as a, possibly split, tongue. On the other hand, the strip 211 in the form of a tongue, which may or may not be split, can be detached together with contact 208 or it can be completely removed from the contacts 207, 208.
The contact 208 in the Figs. 11 and 12 has a split tongue 209 as a piercing contact which is identical to the tongue 210. The contact 208 has a cylindrical rim 213 (Fig. 12) which can be inserted in a recess in a lamp cap made of synthetic material.
Parts in Figs. 13 - 15 which correspond to parts in Figs. 1 - 5 have reference numerals which are 140 higher than those in these Figs. 1 - 5.
The first 156 and the second part 157 of the E27-lamp cap 145 of Fig. 13 have a snap connection 158, 159 (see also Fig. 14) at the open end portion 151, which results in a very strong interconnection of these parts. In cooperation with the cams 160 they also provide a secure connection with a lamp vessel (Figs. 9 and 10). The cams have a surface 160a (Fig. 14), which lies substantially in an axial plane and on which a groove in a lamp vessel exerts pressure through its axial boundary in the case of a torsional force. This pressure has a tangential direction and loads the snap connection 158 - 159 tangentially, i.e. in the direction in which this connection is very strong.
The cams 160 are present at an elastic arm 160b, which finds its origin in that the cams are each surrounded by a U-shaped split 160c in the lamp cap 145. Thanks to this elastic arm 160b, the cam 160 adapts itself to the depths of the grooves 110, 110′. The two parts 156, 157 of the lamp cap 145 with the cams 160 traverse the same path, but in opposite direction, when the lamp cap is applied on the lamp vessel, as the shapers S₁ and S₂ after making the grooves 110, 110′. It is apparent from this that the elastic arms 160b are not deformed before the cams are in full engagement with the grooves. The deformation of these arms 160b in the end position, therefore, is the greatest deformation these arms have ever had; there has been no previous plastic deformation. The elastic arms 160b provide a rattle-free coupling of the lamp cap 145 and the lamp vessel.
The projections 158′ and the recesses 159′ provide an additional coupling of the parts 156, 157, partly or mainly to prevent shifting of these parts along the axial separation surface 155.
Part 157 (Fig. 13) is provided with tapering, flat projections 170 (see also Fig. 15), which during assembly of the lamp cap 145 on a lamp vessel catch the latter's current supply conductors 153, 154 and guide them towards duct-shaped recesses 171, 172 in the base portion 152 of the lamp cap. A partition 170′ in part 156 (Fig. 13) axially shifted relative to the projections 170 encloses the current supply conductors 153, 154 laterally when the parts 156 and 157 are brought together. This enclosing action takes place well before these parts have reached their end positions (see Fig. 15). In a modification of the embodiment shown, the partition 170′ protrudes so far (170˝ in Fig. 15) that it carries along the current supply conductor 153 (Fig. 13) over a distance d perpendicularly to the axis 146, thus lengthening its path inside the lamp cap 145. It can be prevented in this way that the current supply conductor 153 (compare 113 in Fig. 9) extends past the relevant contact (107, Fig. 9) and is visible at the outside of the lamp cap after the lamp has been completely assembled. The duct-shaped recesses are intersected by cavities 173, 174 for accommodating split tongues 210, 209 at contacts 207, 208, respectively (see Figs. 11, 12). The cavity 173′ can accommodate a second tongue 211, if present, at contact 207. This tongue 211 can provide an extra locking of the contact 207 against rotation.
In Fig. 15, recesses 175 are present in the axial cam 163, in which recesses the contact (108, Fig. 11) can be inserted, as well as recesses 165, in which the contact (107, Fig. 11) can be pressed for fixation.

Claims

1. An electric lamp provided with
a translucent lamp vessel (1) with an axis (2) and an end portion (3) on said axis,
an electric element (4) in the lamp vessel,
a plastic lamp cap (5) with an axis (6), which carries electrical contacts (7, 8) and is fixed around said end portion (3) of the lamp vessel (1) and which has a sheath portion (9) with an open end portion (11) surrounding the said end portion (3) of the lamp vessel (1) and a base portion (12) opposite to the open end portion (11), which base portion (12) carries at least one (8) of the contacts,
current supply conductors (13, 14) which extend from the electric element (4) to the contacts (7, 8) of the lamp cap (5),
the lamp cap (5) and the lamp vessel (1) having cooperating cams (20) and grooves (10), which limit a relative rotation and translation of the lamp cap (5), characterized in that
the lamp cap (5) has an axial separation surface (15) and first and second parts (16, 17) arranged laterally of said separation surface (15), which parts (16, 17) are rigidly connected to each other.

2. An electric lamp as claimed in Claim 1,
characterized in that the parts (16, 17) of the lamp cap (5) have means (18, 19) integral therewith which connect the parts to each other.

3. An electric lamp as claimed in Claim 2,
characterized in that the parts of the lamp cap are connected to each other by means of projections (18) and recesses (19), projections (18) of a part (16) being arranged with clamping fit in respective corresponding recesses (19) in the other part (17) each time.

4. An electric lamp as claimed in Claim 3,
characterized in that recesses (19) have a part (21) of reduced width, through which a projection (18) is passed.

5. An electric lamp as claimed in Claim 2,
characterized in that the parts (156, 157) of the lamp cap (145) are connected to each other by means of a snap connection (158, 159).

6. An electric lamp as claimed in Claim 5,
characterized in that the snap connection (158, 159) is present at the open end portion (151) of the lamp cap (145).

7. An electric lamp as claimed in Claim 1 or 2,
characterized in that the current supply conductors (13, 14) are passed to the exterior along the separation surface (15) of the lamp cap (5).

8. An electric lamp as claimed in Claim 1, 2 or 7,
characterized in that the cooperating cams (20) and grooves (10) are shaped so that the end portion (3) of the lamp vessel (1) and the open end portion (11) of the lamp cap (5) have cooperating cross-sections, which are in the form of a flattened ellipse, whose major axis (22) is at right angles to the separation surface (15) of the lamp cap (5).

9. An electric lamp as claimed in Claim 8,
characterized in that the open end portion (81) of the lamp cap (75) has inwardly extending, tapering projections (90′).

10. An electric lamp as claimed in Claim 1, 2, 5 or 7,
characterized in that the lamp vessel (101) has in its end portion (103) a first pair of mirror-imaged grooves (110, 110′) and a second opposing pair of grooves (110, 110′) with which cams (120, 160) in the open end portion (111, 151) of the lamp cap (105, 145) cooperate.

11. An electric lamp as claimed in Claim 10,
characterized in that the grooves (110, 110′) have boundaries (110a, 110′a) which lie in a substantially axial plane (102a - d) of the lamp vessel (101).

12. An electric lamp as claimed in Claim 11,
characterized in that the cams (120, 160) have a surface (160a) which lies in a substantially axial plane (146a) of the lamp cap (145) and which cooperates with the grooves (110, 110′).

13. An electric lamp as claimed in Claim 10 or 12,
characterized in that each cam (160) is connected to the lamp cap (145) via an elastic arm (160b).

14. An electric lamp as claimed in Claim 13,
characterized in that each cam (160) is surrounded by a U-shaped split (160c) in the lamp cap (145).

15. An electric lamp as claimed in Claim 7,
characterized in that the lamp cap (5) has on the separation surface (15) at the base portion (12) an axially directed cam (23), through which a current supply conductor (14) emerges, said current supply conductor being bent backwards around said cam (23), while a metal tube (8) grips with clamping fit around said cam (23) and said current supply conductor (14).

16. An electric lamp as claimed in Claim 15,
characterized in that the metal tube (8) is provided with tongues (24), which engage into the base portion (12) of the lamp cap (5).

17. An electric lamp as claimed in Claim 15,
characterized in that the axially directed cam (23) is provided on the separation surface (15) with a cooperating transversely directed cam (26) and groove (27), which enclose the current supply conductor (14).

18. An electric lamp as claimed in Claim 7,
characterized in that a current supply conductor (13) emerges from the lamp cap (5) near the periphery of the base portion (12) and is bent backwards along the sheath portion (9) of the lamp cap, and in that a metal ring (7) of U-shaped axial section engages the base portion (12) and grips with clamping fit around the sheath portion (9) and around the current supply conductor (13).

19. An electric lamp as claimed in Claim 18,
characterized in that the sheath portion (9) of the lamp cap (5) has an annular groove (25), into which the ring (7) is bent.

20. An electric lamp as claimed in Claim 7,
characterized in that the paths of the current supply conductors (13, 14) between the lamp vessel (1) and the contacts (7, 8) at the lamp cap (5) are substantially equally long.

21. An electric lamp as claimed in Claim 20,
characterized in that the lamp cap (5) has near the periphery of the base portion (12) a transverse projection (28) at the separation surface (15), and a cooperating recess (29), which enclose the current supply conductor (13).

22. An electric lamp as claimed in Claim 21,
characterized in that a part (157) of the lamp cap (145) has flat projections (170) and the other part (156) has a partition (170˝) cooperating with them, so that a current supply conductor (153) is made to run transversely to the axis (146) of the lamp cap over a predetermined distance.

23. An electric lamp as claimed in Claim 7,
characterized in that a current supply conductor (83) emerges from the lamp cap (75) near the periphery of the base portion (82) and is bent towards the sheath portion (79) of the lamp cap, and in that a metal ring (77) in the form of a U-shaped duct engages with a circumferential groove (99) in the base portion (82), from which said current supply conductor (83) emerges, and grips around the sheath portion (79).

24. An electric lamp as claimed in Claim 7,
characterized in that the lamp cap (145) has at the base portion a contact (208) provided with a split tongue (209) which enters the lamp cap and clamps around a current supply conductor (154).

25. An electric lamp as claimed in Claim 24,
characterized in that the lamp cap (145) has a cavity (174) in which the split tongue (209) is accommodated.

26. An electric lamp as claimed in Claim 25,
characterized in that the lamp cap (145) has a duct-shaped recess (172) in which a current supply conductor (154) extends, which recess is intersected by the cavity (174) which accommodates the split tongue.

27. An electric lamp as claimed in Claim 24,
characterized in that the lamp cap (145) has recesses (175) in an axial cam (163) at its base portion (152), into which recess a contact (208) gripping around said cam (163) is inserted.

28. An electric lamp as claimed in Claim 7,
characterized in that the lamp cap has a ring-shaped contact (207) which grips around the sheath portion (149) and has a split tongue (210), which projects into the lamp cap (145) and clamps around a current supply conductor (153).

29. An electric lamp as claimed in Claim 28,
characterized in that the contact (207) has a second tongue (211), and in that the tongues (210, 211) project into cavities (173, 173′) in the lamp cap, respectively.

30. An electric lamp as claimed in Claim 28,
characterized in that the lamp cap (145) has in its sheath portion (149) recesses (165), in which the ring-shaped contact (207) is pressed.

31. An electric lamp as claimed in Claim 7,
characterized in that a current supply conductor (13) has within the lamp cap (55) a duct (41) closed to the other current supply conductor (14).

32. An electric lamp as claimed in Claim 1, 2 or 7,
characterized in that a part (86) of the lamp cap (75) has a rabbet (100) and the other part (87) a rim (91) which is held in said rabbet (100) in order to make the lamp cap (75) at least at its open end portion (81) impervious to light.

33. An electric lamp as claimed in Claim 1, 2 or 3,
characterized in that an internally concave mirror-coated body (04) extends from the open end (11) of the lamp cap (55) laterally of the lamp vessel (1), integral with the lamp cap (55).