Lamp base allowing for electrical contact in various rotational positions

The present invention relates to a screw-in type base for a lighting device being arranged to be mounted in a socket comprising a socket bottom conductor is provided. The base (100, 200, 300) comprising a threaded tubular enclosure (102) extending along an axial direction between a first (102a) and a second (102b) end portion of the enclosure (102), a base bottom conductor (103, 203, 311) arranged to be in electrically conductive contact with a light source (106) of the lighting device (400), and arranged to make electrically conductive, biased contact with the socket bottom conductor when the lighting device (400) is mounted in the socket, wherein the base bottom conductor (103, 203, 311) comprises a compliant thin-walled member (105, 205, 308) arranged such that the base bottom conductor (103, 203, 311) is, relative to the enclosure (102), movable in the axial direction in response to engagement with the socket bottom conductor when the lighting device (400) is mounted in the socket. The present invention also relates to a lighting device (400) comprising the base.

CROSS-REFERENCE TO PRIOR APPLICATIONS

This application is the U.S. National Phase application under 35 U.S.C. § 371 of International Application No. PCT/EP2015/059767, filed on May 5, 2015, which claims benefit of European Patent Application No. 14167609.8, filed on May 9, 2014. These applications are hereby incorporated by reference herein.

FIELD OF THE INVENTION

The present inventive concept relates to a screw-in type base for a lighting device and a lighting device comprising such a base.

BACKGROUND OF THE INVENTION

Lighting devices, such as incandescent light bulbs and light emitting diodes LED lamps are available in various designs. Some lighting device designs are compatible with existing lighting fixtures and sockets. For example, a lighting device may be provided with a threaded base which may be screwed into a socket, i.e. an Edison screw fitting. Such a lighting device comprising a threaded base needs to be hand-tightly fixed to the socket to ensure electrical connection to the socket such that the light source of the lighting device may be powered.

The lighting devices that are currently available on the market are predominantly rotational symmetric. The light emission and visual appearance of such a lighting device does not significantly depend on the rotational angle of the lighting device after it is screwed into the socket of a luminaire. In other words, the actual rotational position of the lighting device, after it is hand-tightly fixed to the socket, does therefore not influence the visual appearance of the luminaire. This same reasoning holds for a lighting device having a rotational symmetric light emission, since the directionality of the light emitted from the luminaire is not affected by the rotational position of the light source.

If, however, the lighting device and/or its light emission is rotationally asymmetric the visual appearance and/or directionality of the light emission depend on the rotational angle of the lighting device.

A lighting device provided with a threaded base is typically screwed into a socket until it makes electrical contact and is hand-tight. However, the appearance of a lighting device being rotationally asymmetric or the light emission of a lighting device having a rotationally asymmetric light emission may be pointed at a non-ideal angle when screwed into the socket.

Hence, it is desirable to be able to rotationally adjust the position of the lighting device or to direct its light emission by turning the lighting device.

It may be possible to turn the lighting device somewhat to aim it correctly but that will loosen the device in the socket and may diminish or even break the electrical connection. This condition could either cause the light to go out, or result in a poor electrical connection that gets hot and creates a fire hazard.

In U.S. Pat. No. 8,147,267 a solution to this problem is presented. According to U.S. Pat. No. 8,147,267 a spring coil biased movable conductor mounted in the center of the base is used in order to solve the problem of being able to turn a rotationally asymmetric lighting device with retained good electrical connection between the lighting device and the socket.

However, there is a need to find new means to direct asymmetric lighting devices with a screw-in type base.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide new means to direct asymmetric lighting devices with a screw-in type base. Such a screw-in type base shall preferably also be designed to be easy and cheap to manufacture. The reduction in number of parts required and the reduced complexity in assembly contribute towards the reduction of cost.

According to a first aspect of the invention, these and other objects are achieved by providing a screw-in type base for a lighting device being arranged to be mounted in a socket comprising a socket bottom conductor. The base comprising a threaded tubular enclosure extending along an axial direction between a first and a second end portion of the enclosure; a base bottom conductor arranged to be in electrically conductive contact with a light source of the lighting device, and arranged to make electrically conductive, biased contact with the socket bottom conductor when the lighting device is mounted in the socket, wherein the base bottom conductor comprises a cylindrical compliant thin-walled member partly embedded in the base and arranged such that the base bottom conductor is, relative to the enclosure, movable in the axial direction in response to engagement with the socket bottom conductor when the lighting device is mounted in the socket.

By providing a base bottom conductor that is axially movable, in relation to the enclosure, the base may be rotated in the socket without reducing or breaking the electrical contact between the base bottom conductor and the socket bottom contact. It is thereby possible to rotationally adjust the position of the lighting device or to direct its light emission by turning the base in the socket.

The biased contact between the base and the socket further mitigates that the base becomes loose in the socket.

The compliant thin-walled member further reduces the building height needed for forming the base.

The wording compliant thin-walled member should be construed as a substantially flat or dome shaped structure that is conformed as a result of forces being exerted on it. In other words, the compliant thin-walled member is resilient such that it is able to substantially recoil or spring back into shape after bending, stretching, or being compressed. Hence, the compliant thin-walled member is flexible and at least partly elastically deformable. The material of which the compliant thin-walled member is composed of may be resilient. The compliant thin-walled member may alternatively be shaped such that it provides a resilient structure.

The compliant thin-walled member may be overmolded during production to further reduce the number of parts required to secure the compliant member to the lamp base/cap.

The base bottom conductor may be centrally arranged in the base. This makes the base rotationally symmetric which simplifies the mounting of the base in the socket.

The base bottom conductor may be in electrically conductive contact with the light source of the lighting device via an electrically conductive wire. This provides efficient assembly of the lighting device and ensures efficient contacting of the lighting device such that it may be powered when mounted in the socket. The use of the electrically conductive wire for establishing electrically conductive contact between the base bottom conductor and the light source also provide for such that the base bottom conductor may be moved in relation to the light source which typically is fixed in relation to the tubular enclosure.

The base bottom conductor may further comprise an electrically conducting contact pin, and the base may further comprise an insulator attached to the first end portion of the enclosure, the insulator having an inner portion facing towards an inner space of the enclosure, an outer portion facing away from the inner space, and a channel for receiving the electrically conducting contact pin, the channel extending from the outer portion, through the insulator and leading into the inner space, wherein the compliant thin-walled member is arranged in the inner space. This arrangement has the advantage that the base may have an appearance that resembles known lamp bases such as the Edison screw mount or the Casun cap. The compliant thin walled member may by being in the inner space of the enclosure be better protected from external forces that may mechanically damage the compliant thin walled member. A more durable base may thereby be obtained.

A further advantage of the compliant thin-walled member is that less space is used within the lamp base/cap to locate the contact than is required in the prior art devices.

The contact pin may be attached to the compliant thin-walled member. This is advantageous as it may simplify the assembly of the base. The contact pin is further held in position by the compliant thin-walled member which mitigates problems associated with the contact pin becoming loose in the base.

The compliant thin-walled member may comprise an electrically conducting material. The electrical contact between the base and the socket may thereby be facilitated by the compliant thin-walled member. In other words, the compliant thin-walled member may constitute the base bottom conductor.

The electrically conducting wire may be in electrical connection with the compliant thin-walled member. This simplifies assembly of the bas and ensures efficient contacting of the lighting device such that it may be powered when mounted in the socket. The electrically conducting wire may further be compliant to the movement of the thin-walled member.

The electrically conducting wire may be attached to the contact pin.

The base may further comprise an insulator attached to the first end portion of the enclosure, the insulator having an inner portion facing towards an inner space of the enclosure and an outer portion facing away from said inner space, wherein the compliant thin-walled member is arranged at the outer portion of the insulator. This arrangement further reduces the building height needed to form the base.

The base may further comprise a shell in which the compliant thin-walled member is formed. The shell may thereby provide stability to the compliant thin-walled member.

The shell may be partly embedded in the insulator, which simplifies manufacturing of the base.

According to a second aspect a lighting device is provided. The lighting device comprising a base according to any one of the above embodiments and a lighting module arranged on the base. The function and benefits of using a lighting device comprising the base are described above. The above mentioned features, when applicable, apply to this second aspect as well. In order to avoid undue repetition, reference is made to the above.

DETAILED DESCRIPTION

FIG. 1illustrates a screw-in type base100for a lighting device according to an embodiment of the present invention. The base100is arranged to be mounted in a socket comprising a socket bottom conductor. The socket is for clarity not shown. The base100comprises a threaded tubular enclosure102extending along an axial direction between a first102aand a second102bend portion of the enclosure102and a base bottom conductor103. The threaded tubular enclosure102and the base bottom conductor103are electrically conductive. Typically the threaded tubular enclosure102and the base bottom conductor103comprise metals.

It should be noted that the socket may comprise threads corresponding to the threads of the enclosure102. The outer dimensions of the enclosure102and the corresponding inner dimensions of the socket may by way of example correspond to those of the E14 or E27 Edison screw fitting.

The enclosure102and the base bottom conductor103are electrically isolated from each other by an insulator104.

The base bottom conductor103is further in electrically conductive contact with a light source106of the lighting device via an electrically conductive wire107a. The tubular enclosure102is in electrically conductive contact with the light source106of the lighting device via an electrically conductive wire107b. The wires107a,107bensure efficient contacting of the lighting source106such that the lighting device may be powered when mounted in the socket. The electrically conductive wire107ahas preferably a length that is at least as large as the distance the base bottom conductor103may move in response to engagement with the socket bottom conductor when the lighting device is mounted in the socket.

The insulator104may comprise a polymer material, such as an engineering thermoplastic, for instance, polybutylene terephthalate (PBT) or polycarbonate (PC), a glass or a ceramic material. The insulator104may advantageously be injection molded.

The base bottom conductor103further comprises a compliant thin-walled member105. The compliant thin-walled member105forms the base bottom conductor103and has a bulging portion103awhich is arranged to make an electrically conductive contact with the socket bottom conductor. The compliant thin-walled member105may comprise stainless steel. As an inherent feature of the thin-walled member105being compliant the thin-walled member105is resilient. As a result of the compliant thin-walled member105being resilient, the compliant thin-walled member105, and especially the bulging portion103a, may move in an, relative to the enclosure102, axial direction in response to engagement with the socket bottom conductor when the lighting device is mounted in the socket.

The compliant thin-walled member105disclosed inFIG. 1has a dome shape which provides a resilient structure. By this arrangement a base bottom conductor103is provided which ensures a biased electrically conductive contact with the socket bottom conductor. Hence a base bottom conductor103that is axially movable, in relation to the tubular enclosure102is provided. The base100may therefore be rotated in the socket without reducing or breaking the electrical contact between the base bottom conductor103and the socket bottom conductor. It is thereby possible to rotationally adjust the position of the lighting device or to direct its light emission by turning the base100in the socket.

The biased contact provided between the base100and the socket further mitigates that the base100becomes loose in the socket.

Hence, the base bottom conductor103may be set in an extended position and a compressed position and any position there between. The distance between the extended position and the compressed position is preferably being large enough such that the base100of the lighting device may be rotated at least 180 degrees. In other words, base bottom conductor103may move a distance that corresponds to at least half the height of the tread of the treaded tubular enclosure102, without reducing or breaking the electrical contact between the base bottom conductor103and the socket bottom contact.

Depending on the symmetry of the lighting device, in another embodiment the distance between the extended position and the compressed position may be smaller than the above mentioned distance corresponding to at least half the height of the tread of the treaded tubular enclosure102. For example the distance between the extended position and the compressed position of the base bottom conductor103may be set such that the base100may be rotated for example anywhere between 0-180 degrees with remaining contact between the base bottom conductor103and the socket bottom conductor.

The base bottom conductor103is further centrally arranged in the base100. This makes the base100rotationally symmetric which simplifies the mounting of the base100in the socket.

According to another embodiment an electrically conducting wire may be in electrically conductive contact with the compliant thin-walled member.

The compliant thin-walled member105and the bulge103amay further be joined together. They may e.g. be joined by welding or gluing them together.

The person skilled in the art understands that the compliant thin-walled member may flexible and biased in different ways than illustrated inFIG. 1. The thin-walled member may for example comprise biased resilient plate like structure similar to the one illustrated inFIG. 2.

FIG. 2illustrates a screw-in type base200, according to another embodiment of the present invention, for a lighting device being arranged to be mounted in a socket. The socket comprising a socket bottom conductor is for clarity not shown.

The base200comprises a threaded tubular enclosure102extending along an axial direction between a first102aand a second102bend portion of the enclosure102, a base bottom conductor203, and an isolator204.

The base bottom conductor203comprises a compliant thin walled member205and an electrically conducting contact pin206. The insulator204is attached to the first end portion102aof the enclosure102, such that the isolator204has an inner portion204afacing towards an inner space207of the enclosure102and an outer portion204bfacing away from the inner space207. The isolator204further comprises a channel208for receiving the electrically conducting contact pin206. The channel208extends from the outer portion204b, through the insulator204and leads into the inner space207.

The compliant thin walled member205is arranged in the inner space207of the enclosure102such that it may be better protected from external forces that may mechanically damage it. A more durable base200may thereby be obtained.

The contact pin206, made of electrically conducting material, may further attached or joined to the compliant thin-walled member205. The contact pin206may e.g. be attached or joined to the compliant thin-walled member205by means of welding or gluing. The contact pin206is thereby held in position by and in electrical contact with the compliant thin-walled member205. The contact pin206is thereby hindered from falling out of the base200.

The compliant thin-walled member205may be made of an electrically conducting material such as stainless steel. In case of the thin-walled member205being made of electrically conducting material the electrical contact between the contact pin206and the socket may be facilitated via the thin-walled member205.

An electrically conducting wire107ais further arranged in the inner space207of the base200and is in electrical connection with the compliant thin-walled member205. Hence, efficient contacting of the lighting device may be provided such that the lighting device may be powered when mounted in the socket. The electrically conducting wire107ais as discussed above compliant to the movement of the thin-walled member205.

The thin-walled member205is formed as a resilient plate like structure. The thin-walled member205further biases the contact pin206such that the contact pin206is in an extended position209when no external force is applied to it.

As the compliant thin-walled member205is resilient it and the contact pin206are axially movable in relation to the tubular enclosure102. When an external force is applied to the contact pin206, such as when the base200is mounted in the socket, the compliant thin-walled member205may bend. As a result, the compliant thin walled member is moved away from the inner portion204aof the isolator204and the contact pin206reaches a compressed position210. The base bottom conductor203is thereby arranged such that the base200may be rotated in the socket without reducing the efficiency in powering the lighting device.

Hence, the base bottom conductor203may be set in the extended position209and the compressed position210and any position there between. The distance between the extended position209and the compressed position210is preferably being large enough such that the base200of the lighting device may be rotated at least 180 degrees. In other words, the contact pin206may move a distance that corresponds to at least half the height of the tread of the treaded tubular enclosure102, without reducing or breaking the electrical contact between the base bottom conductor203and the socket bottom contact.

As describe above, depending on the symmetry of the lighting device, in another embodiment the distance between the extended position209and the compressed position210may be smaller than the above mentioned distance corresponding to at least half the height of the tread of the treaded tubular enclosure102.

The electrically conducting wire may alternatively be attached to the contact pin. This is for example advantageous if the compliant thin-walled member comprises an electrically non-conducting material.

According to other embodiments the compliant thin-walled member may comprise a compressible resilient material. The compliant thin-walled member may comprise a resilient membrane such as silicone. The silicone may further be electrically conductive.

FIGS. 3 and 4illustrate a screw-in type base300, according to another embodiment of the present invention, for a lighting device being arranged to be mounted in a socket.FIG. 3illustrates a cross-sectional side view of the base300andFIG. 4illustrates the same base300in a perspective view.

The base300comprises an insulator304attached to the first end portion102aof an enclosure102. The insulator304has an inner portion304afacing towards an inner space306of the enclosure102and an outer portion304bfacing away from the inner space306. A compliant thin-walled member308is further arranged at the outer portion304bof the insulator304. The compliant thin-walled member308has a U-shaped channel312such that a resilient tongue309is formed. The tongue309further has a bulge310which facilitates an effective electrically conductive contact with the socket. The compliant thin-walled member308thereby forms a base bottom conductor311. This arrangement reduces the building height needed to form the base300.

The compliant thin-walled member308is further formed in a shell313. The shell may thereby provide stability to the compliant thin-walled member308. The shell313is cylindrical in shape and surrounds the tongue309. The tongue309may thereby be formed by means of punching through the cylindrical shell313. The shell313is further partly embedded in the insulator304which simplifies manufacturing of the base300.

The resilient tongue309of the compliant thin-walled member308further biases the bulge310in such way that the bulge310is in an extended position313when no external force is applied to it.

As the compliant thin-walled member308, i.e. the tongue309is resilient it is axially movable in relation to the tubular enclosure102. When an external force is for example applied to the bulge310, such as when the base300is mounted in the socket, the tongue309of the compliant thin-walled member308may bend. As a result, the bulge310reaches a compressed position314. A base bottom conductor311is thereby provided such that the base300may be rotated in the socket maintaining electrically conductive contact between the base bottom conductor311and the socket bottom conductor of the socket.

Hence, the base bottom conductor311may be set in the extended position315and the compressed position314and any position there between. The distance between the extended position315and the compressed position314is preferably being large enough such that the base300of the lighting device may be rotated at least 180 degrees. In other words, the bulge310may move a distance that corresponds to at least half the height of the tread of the treaded tubular enclosure102, without reducing or breaking the electrical contact between the base bottom conductor311and the socket bottom contact.

As describe above, depending on the symmetry of the lighting device, in another embodiment the distance between the extended position and the compressed position may be smaller than the above mentioned distance corresponding to at least half the height of the tread of the treaded tubular enclosure102.

The skilled person in the art should understand that the compliant thin-walled member may be formed differentially than what is disclosed onFIGS. 3 and 4.

FIG. 5illustrates a lighting device400according to one embodiment of the present invention. The lighting device400comprises a base300arranged to be mounted in a socket comprising a socket bottom conductor, not shown. The lighting device400further includes a lighting module402, arranged on the base300. The lighting module402comprises at least one light source, not shown. The lighting module402is asymmetric and as a consequence the lighting device400is rotationally asymmetric. The base300is the base disclosed above in relation toFIGS. 3 and 4. The base300comprises a tubular enclosure102and a base bottom conductor311. The base bottom conductor311is axially movable, in relation to the tubular enclosure102, such that the base300may be rotated after it is mounted in the socket without reducing or breaking the electrical contact between the base bottom conductor311and a socket bottom contact. It is thereby possible to rotationally adjust the position of the lighting device400by turning the base300in the socket, without reducing the efficiency of lighting device400. The visual appearance, i.e., its rotational position may thereby be tuned by changing the rotational angle of the lighting device400in the socket. Hence, the lighting module402may be oriented in a preferred rotational direction.

According to another embodiment of the present invention a lighting device may be provided comprising a symmetric lighting module, but having a rotationally asymmetric light output. Again, by being able to rotationally adjust the position of the lighting device, by turning the base of the lighting device in the socket, the light emission from the lighting device may be tuned.

It should be noted that in other embodiments the base300may be any base according to the subject matter of the present invention. The person skilled in the art realizes that the present invention by no means is limited to the preferred embodiments described above. On the contrary, many modifications and variations are possible within the scope of the appended claims.

For example, the tubular enclosure and the base bottom conductor may consist of the same or different electrically conductive materials.

It should further be noted that the lighting device may comprise various types of light sources. For example, the lighting device may be a light emitting diode LED or an electric lamp comprising one or more halogen light sources.