EP1633024B1 - Wedge-base lamp socket having a centering ring - Google Patents

Abstract

The lamp socket, comprising a base (1) and two or more electrical contact strips (20) for the lamp electrodes, has a centering ring (3) with projecting tongues on one side to engage with the base, and centering lugs on the other side that have inclined surfaces making contact with the surface of the lamp bulb. The contact strips are made from spring steel or stainless steel.

Description

The present invention generally relates to the field of sockets for filament lamps with a glass base. More particularly, the invention relates to a lampholder for glass base suitable for use in lighting and / or signaling devices for motor vehicles, including traffic lights.

It will be mentioned later that applications to traffic lights, for the sake of brevity.

Lamps with a base of glass ("wedge-base lamp" in English) are of interest for integration into a traffic light of a motor vehicle. Indeed, these lamps have the advantage of a smaller footprint compared to bayonet lamps used more conventionally in traffic lights. This feature of a smaller footprint is likely to facilitate the achievement of more compact traffic lights and providing a better optimization of the surfaces of optical elements, such as reflector or other, included in these lights.

Thus, W16W type lamps can advantageously replace P21 W bayonet lamps in certain traffic lights.

The use of lamps with a glass base is, however, hampered by the difficulties encountered by manufacturers in maintaining a close tolerance for the positioning of the filament in the bulb of the lamp. For example, in the case of a W16W type lamp, the tolerance on the distance between the filament and lamp retention grooves may be of the order of ± 2.3 mm.

However, in a traffic light, as in a lighting projector, the filament of the lamp must occupy a specific position with respect to optical elements included in the lamp or the projector, and this in order to obtain the optical performance sought. This results in a very tight dimensional tolerance for the mechanical connection between the lamp and its socket.

The sockets currently available for lamps with a glass base are unsuitable for use in a signaling light for a motor vehicle. Indeed, these bushings respond poorly to different mechanical stresses to which is generally subject a traffic light. Thus, tests carried out by the inventors show that the casings of the prior art do not guarantee a sufficiently reliable positioning of the filament with respect to the optical elements during the application of mechanical vibrations.

Of the currently available lamp base lampholders, it is known from the document EP0404135B1 a socket intended to be mounted on an electrically insulating substrate 8.

A sectional view of the socket according to EP0404135B1 is shown at the Fig.6 in this application.

This socket according EP0404135B1 comprises hook-shaped electrical contact blades 6a and 6b and a sheath 7 for holding the base of the lamp in the socket.

The blades 6a and 6b are fixed on the substrate 8 and are arranged to clamp the lamp base 5a together and to make electrical contact with electrodes thereof. The blades 6a and 6b each have a hook shape and are conventionally made of brass or phosphorous copper.

The sheath 7 is made of an electrically insulating material and is clipped onto the substrate. The sheath 7 is provided with two hooks 7a. The hooks 7a fit into grooves in the base 5a and serve to maintain the position of the lamp.

The combined action of the blades 6a, 6b and hooks 7a on the base 5a ensures retention of the lamp in the socket, but this action is however not sufficient to meet all the constraints that apply during the design of a traffic light, and in particular in terms of the vibratory response of the traffic light.

The main object of the present invention is to provide the prior art with the improvements necessary for wider use of lamps with a glass base in lighting and / or signaling devices for a motor vehicle.

The present invention aims first of all at providing a lamp base with a glass base comprising a base and at least two electrical contact blades mounted in the base for electrically connecting the electrodes of the lamp to a power supply circuit. electric contact blades each having a resilient clip forming part into which the glass base of the lamp is inserted. According to the invention the base comprises a centering piece made in the form of a ring extending on a first face, by at least one leg adapted to provide a fixed positioning of the centering piece on the base, and having, on a second face, centering elements forming a portion in contact with the base of the bulb of the lamp in order to center in a predetermined manner the lamp in the base and to oppose a movement of the lamp relative to the base.

It is considered here that the term "base" designates the portion of the bulb which is adjacent to the lamp base, this portion generally having at least partially a flared shape or a shape with inclined faces in the lamps with a glass base.

The invention thus provides a socket perfectly adapted to use in a traffic light for a motor vehicle.

According to another preferred feature, the contact blades are made of spring steel. According to a preferred embodiment, the contact blades are made of stainless steel strip steel for spring.

Preferably, the resilient clamp portion of an electric contact blade is designed to exert on the base a clamping force adapted to the type of lamp, W16W or W5W.

Due to their separation into two distinct parts, the centering piece and the base can easily be made of different materials, the material of the centering piece being chosen to be adapted to direct thermal contact with the base of the bulb.

This separation into two separate parts also has the advantage of keeping a standard base and only change the centering part when you want to adapt the socket according to the invention to different types of lamp, for example, W16W or W5W.

Preferably, the centering piece is made of polycarbonate and the base is made of polypropylene. The use of a low cost material such as polypropylene for the base allows a better compromise of cost for the manufacture of the socket.
According to a preferred embodiment, the centering piece comprises two axially symmetrical lugs extending from its first face and able to snap onto the base, and on the second face, at least four centering elements forming the part in contact with the base. Preferably, at least one centering element has the shape of a wedge whose inclined face is in contact with a flared or inclined portion of the base of the bulb.

According to yet another characteristic, the resilient part forming a gripper of a contact blade comprises two resilient contact tongues in facing each other and forming between them a nip zone, the contact tongues having a substantially curved profile and comprising free ends spaced apart from each other and oriented towards the bulb.

According to another preferred embodiment, the socket according to the invention is integrated in a lamp holder for lighting and / or signaling device comprising several sockets.

Correlatively, the invention also relates to a lighting and / or signaling device, in particular for a motor vehicle, in which is included at least one socket as briefly described above.

• la Fig.1 est une vue globale en perspective d'une douille selon l'invention et de la lampe portée par celle-ci ;
• la Fig.2 est une vue en perspective d'une embase comprise dans la douille de la Fig.1 ;
• la Fig.3 est une vue en perspective de deux lames de contact électrique comprises dans la douille de la Fig.1 ;
• la Fig.4 est une vue en perspective d'un anneau de centrage compris dans la douille de la Fig.1 ;
• la Fig.5 est une vue en coupe axiale de l'anneau de la Fig.4, et montre également le positionnement d'une lampe par rapport à l'anneau ; et
• la Fig.6 est une vue en coupe d'une douille selon la technique antérieure.

Other aspects and advantages of the present invention will appear more clearly on reading the description of particular embodiments which will follow, this description being given by way of nonlimiting example and with reference to the accompanying drawings, in which: which :

• the Fig.1 is an overall perspective view of a socket according to the invention and the lamp carried by it;
• the Fig.2 is a perspective view of a base included in the socket of the Fig.1 ;
• the Fig.3 is a perspective view of two electrical contact blades included in the socket of the Fig.1 ;
• the Fig.4 is a perspective view of a centering ring included in the sleeve of the Fig.1 ;
• the Fig.5 is an axial sectional view of the ring of the Fig.4 , and also shows the positioning of a lamp with respect to the ring; and
• the Fig.6 is a sectional view of a socket according to the prior art.

The invention is now described in detail, essentially through a preferred embodiment in which the socket according to the invention is integrated in a lamp holder intended to be mounted on a block of traffic lights for a motor vehicle.

A lamp holder for traffic lights is conventionally formed of a molded plastic body equipped with mechanical assembly means and electrical connection. Lamps are inserted into corresponding lampholders of the lamp holder in order to be connected to the vehicle power supply circuit and to form the light sources of the different lights of the signal block. After insertion of the lamps, the lamp holder is assembled on the signal block and closes a rear opening thereof.

With reference to Figs.1 and 2 , the socket according to the invention essentially comprises a base 1, electrical contact blades 20 and 21 and a centering ring 3.

As shown in Fig.1 a lamp with a glass base 5, for example of the W16W type, is inserted into the socket.

In this preferred embodiment, the base 1 is integrally molded with the body 4 of the lamp holder and thus forms a single piece therewith. Body 4 is only partially shown Fig.1 .

The base 1 and the body 4 are made here in the same low-cost material such as for example polypropylene. The base 1 is preferably made in the form of a generally hollow body.

As shown also to Figs.1 and 2 conductive strips 40 and 41 forming part of a cut-off electrical circuit of the lamp holder are provided for connecting the contact blades 20 and 21 to the vehicle power supply circuit.

The conductive strips 40 and 41 have folded ends (the folded end 400 of the band 40 is shown in FIG. Fig.2 ) which engage in female connecting portions 200 and 210 of the contact blades 20 and 21, respectively.

The contact blades 20 and 21 are shown in detail in FIG. Fig.3 , with the same positioning relative to each other as they once mounted in the base 1.

The contact blades 20 and 21 have in this embodiment substantially identical shapes and dimensions. Of course, the contact blades may be different in other embodiments.

As shown in Fig.3 each contact blade 20, 21 comprises an elastic part forming a clamp 201, 211 into which the glass base of the lamp 5 is inserted.

The gripper portions 201, 211 are housed in an upper open cavity 10 ( Fig.2 ) of the base 1. Four notches 11 are also provided in the base 1 in order to be able to install the gripper parts 201 and 211 in the cavity 10.

A gripper portion 201, 211 comprise two elastic contact tongues facing one another and forming between them a nip area. The contact tabs have a substantially curved profile. The nip region between the contact tabs is located at generally convex surface portions thereof.

When the base of the lamp 5 is inserted between the tongues of an electrical contact blade, an electrical connection is established between the tongues and a wire electrode of the lamp 5.

The facing contact tabs are connected in their lower parts and form at their level a common portion 202, 212 which extends to the female connection part 200, 210. In their upper parts, the contact tabs have free ends oriented towards the bulb of the lamp 5. These free ends are spaced apart from each other by the effect of the curved profile of the contact tongues, thus facilitating the insertion of the base of the lamp 5 between the contact tabs.

According to the invention, the contact blades 20 and 21 are preferably of spring steel. More specifically, in this preferred embodiment, the contact blades are made of stainless steel strip steel for spring.

The tests carried out by the inventors have shown that steel, unlike brass and other materials usually used for electrical contacts in the sockets, makes it possible to obtain a pinch force capable of guaranteeing correct retention of the lamp. in the socket. Preferably, the collet elastic portions 201, 211 are designed to exert on the base a nipping force adapted to the type of lamp, W16W or W5W.

It should be noted here that the terms "correct retention" must be interpreted in the context of lighting and automobile signaling. Thus, the retention of the lamp 5 in the socket will be judged correct if maximum displacement stresses of the lamp relative to the socket are satisfied when specific mechanical stresses, such as vibrations and shocks, are applied to the lamp assembly. socket. Indeed, when the lamp is assembled to the optical elements of the traffic light and is subjected to mechanical stresses, the movements of its filament must remain within clearly defined limits with respect to a focus of these optical elements, and this in order to not disturb the optical performance of the fire.

With particular reference to Figs.4 and 5 , it is now described the centering ring 3.

The centering ring 3 generally has a shape of hollow cylinder of revolution which is extended in its lower part by two axially symmetrical lugs 30 and 31. In its upper part, the centering ring 3 comprises four centering elements 32 which, in this preferred embodiment, are each in the form of a wedge.

According to the invention, the centering ring 3 is made of a material capable of withstanding the thermal stresses imposed by the lamp 5, and in particular by direct contact with the bulb of the lamp 5. For example, the ring of centering 3 can be made of polycarbonate (PC).

The tabs 30 and 31 have the function of locking by clipping the centering ring 3 on the base 1. The lugs 30 and 31 respectively comprise protruding lugs 310 and 311 located at their lower free ends.

When mounting the ring 3 on the base 1, the lower ends of the tabs 30 and 31 are respectively inserted into two complementary clipping slots 12 shown in FIG. Fig.2 . A lower annular surface 33 of the ring 3 then comes into contact with an upper face 13 of the base 1, thus ensuring a positioning along the axis X. The lugs 310 and 311 hang on an internal rim of the clipping notches 12 , thus locking the ring 3 on the base 1.

A positioning of the ring 3 in the base 1 along the two perpendicular axes Y and Z is obtained by means of four abutment elements 14 of the base 1.

The stops 14 are shown at the Fig.2 . The four stops 14 are located around the axis of symmetry along X of the base 1, on a circle perpendicular to this axis of symmetry and centered on it. The stops 14 are separated from each other by an angle of 45 °. Each stop 14 has a face 140 oriented towards the axis of symmetry of the base 1, which is intended to come into positioning contact with an outline wall 34 of the ring 3.

We will also notice at the Fig.2 , a face 141 and a flange 142 which are also provided in each of the stops 14 for positioning the socket in an optical device such as reflector or the like.

Of course, the above description of the stops 14 should not be interpreted in a limiting manner, because these stops 14 may be modified by those skilled in the art to adapt the sleeve according to the invention to different possible applications. Thus, for example, in certain variants, the abutments 14 may be replaced by a collar provided with notches provided for mounting the contact blades 20 and 21 in the base 1.

With reference again to Figs.4 and 5 the corners 32 of the ring 3 each comprise an inclined face intended to come into contact with the bulb of the lamp 5, at a base 50 of the bulb.

The base of the bulb is a lower part of the bulb, adjacent to the base of the lamp. As shown in Fig.5 , in this embodiment adapted to a W16W lamp, the base 50 is located between a cylindrical portion of revolution 51 of the bulb and the base of the lamp 5.

Preferably, in this embodiment for a W16W lamp, the contact of the corners 32 with the base 50 occurs at a flared portion 52 thereof

In the case of an embodiment adapted to a W5W lamp, the bulb base of the W5W lamp comprises two substantially plane and axially symmetrical inclined faces at which the contact with the corners 32 preferably intervenes.

The above description of the centering elements 32 should not be interpreted in a limiting manner, since the number and shape of these elements 32 may be modified by those skilled in the art in order to adapt the socket according to the invention to different possible applications.

Thus, for example, in other embodiments, the centering elements 32 may be replaced by a flange providing continuous contact over a full circumference of the base 50.

Note however that the preferred embodiment described here, with several discrete centering elements, offers the advantage of thermal contacts with the bulb that remain punctual. The temperature of the material of the centering ring is thus lower than that which would be achieved with a larger contact surface, thus improving the durability of the material.

Claims (10)

1. Socket for a wedge-base lamp, comprising a base (1) and at least two electrical contact studs (20, 21) which are fitted in the said base (1) in order to connect electrodes of the lamp (5) electrically to an electric supply circuit, the said electrical contact studs (20, 21) each comprising a resilient part which forms a gripper (201, 211) into which the said wedge base of the lamp (5) is inserted, characterised in that the said base (1) comprises a centring part (3) which is produced in the form of a ring, which is extended on a first surface by at least one lug (30, 31) which can assure fixed positioning of the said centring part (3) on the said base (1), and which on a second surface has centring elements (32) which form a part in contact with the base (50) of the bulb of the lamp (5), in order to centre the lamp (5) in a predetermined manner in the said base (1) and to oppose displacement of the lamp (5) relative to the said base (1).
2. Socket according to claim 1, characterised in that the said contact studs (20, 21) are made of a spring steel or stainless steel strip for springs.
3. Socket according to claim 1 or claim 2, characterised in that the said resilient part which forms a gripper (201, 211) is designed to as to exert on the said base a gripping force which is suitable for the type of lamp (5).
4. Socket according to any one of claims 1 to 3, characterised in that the said centring part (3) and the said base (1) are made of different materials, the material of the said centring part (3) being selected in order to be suitable for direct thermal contact with the said base (50).
5. Socket according to claim 4, characterised in that the said centring part (3) has a polycarbonate (PC) basis, and the said base (1) has a polypropylene (PP) basis.
6. Socket according to any one of claims 1 to 5, characterised in that the said centring part (3) comprises two axially symmetrical lugs (30, 31) which extend from its first surface, and can be clipped onto the said base (1), and on a second surface it has at least four centring elements (32) which form the said part in contact with the said base (50).
7. Socket according to claim 6, characterised in that at least one of the said centring elements (32) is in the form of a wedge, an inclined surface of which is in contact with a splayed (52) or inclined part of the said base (50).
8. Socket according to any one of claims 1 to 7, characterised in that the said resilient part which forms a gripper (201, 211) of a said contact stud (20, 21) comprises two resilient contact tongues which are opposite one another and form a gripping area between one another, the said contact tongues having a substantially curved profile, and comprising free ends which are spaced from one another and are oriented towards the said bulb.
9. Socket according to any one of claims 1 to 8, characterised in that it is integrated in a lamp-holder (4) for a lighting and/or signalling device comprising a plurality of sockets.
10. Lighting and/or signalling device, in particular for a motor vehicle, characterised in that it comprises at least one socket according to any one of claims 1 to 9.

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