LED LIGHTING BULB AND MANUFACTRING METHOD

Abstract

A LED lighting bulb (10) has a lighting driver (28) which is located within the bulb envelope (12). During assembly, the lighting driver (28) may be positioned away from an opening (14) of the envelope (12) so that high temperature sealing of a stem portion (22) of the end cap (16) to the envelope opening (12) can take place. The lighting driver (28) can then be pulled into position against the stem portion (22), and assembly of the end cap (16) can then be completed.

Claims

1. A LED lighting bulb comprising: an envelope having an opening; an LED arrangement being enclosed in the envelope; an end cap at the opening comprising a first terminal, a second terminal and a stem portion which closes the opening; a first wire and a second wire extending from the stem portion into the envelope; a lighting driver at an envelope side of the stem portion, the lighting driver comprising a shape feature for allowing the lighting driver to slide relative to the first wire and the second wire during assembly, and the lighting driver being electrically connected to the first wire and the second wire; a first tube extending from the stem portion on an opposite side to the envelope; a second tube extending from the stem portion on an opposite side to the envelope; and a first supply wire which makes electrical connection between the first terminal and the lighting driver through the first tube and through the stem portion; and a second supply wire which makes electrical connection between the second terminal and the lighting driver through the second tube and through the stem portion.

2. A LED lighting bulb as claimed in claim 1, wherein the first supply wire is sealed within the first tube and the second supply wire is sealed within the second tube.

3. A LED lighting bulb as claimed in claim 1, wherein the shape feature comprises a first through hole or slot around the first wire and a second through hole or slot around the second wire.

4. A LED lighting bulb as claimed in claim 1, wherein the lighting driver comprises an anode output wire and a cathode output wire which are soldered to the first wire and second wire respectively.

5. A LED lighting bulb as claimed in claim 1, wherein the holes or slots are electrically connected to output terminals of the lighting driver and the output terminals of the lighting driver are connected the first and second wires by electrical contact between the first and second wires and the holes or slots.

6. A LED lighting bulb as claimed in claim 1, wherein the envelope is glass and the stem portion is sintered to the envelope.

7. A LED lighting bulb as claimed claim 1, wherein the first and second tubes are glass and they are each sintered around their respective supply wire.

8. A LED lighting bulb as claimed in claim 1, wherein the end cap further comprises a terminal portion which defines the first and second terminals.

9. A LED lighting bulb as claimed in claim 1, wherein the LED arrangement is connected between the first wire and the second wire.

10. A method of manufacturing a LED lighting bulb comprising: providing an envelope having an opening; providing a stem portion of an end cap, having a first wire and a second wire extending from the stem portion; mounting a lighting driver along the first wire and second wire, wherein the lighting driver comprises first and second supply wires which extend through the stem portion and each through a respective tube which extends back from the stem portion; providing an LED arrangement within the envelope; hermetically connecting the stem portion to the opening of the envelope with the lighting driver remote from the stem portion and within the envelope; pulling the lighting driver towards the stem portion along the first and second wires using the first and second supply wires; sealing the tubes around the first and second supply wires; assembling the end cap by connecting the first and second supply wires to first and second terminals of a terminal portion of the end cap and connecting the terminal portion to the stem portion.

11. A method as claimed in claim 10, wherein the envelope and the tubes are glass, and the hermetically connecting and the sealing comprise sintering.

12. A method as claimed in claim 10, further comprising evacuating the envelope or filling the envelope with a gas before sealing the tubes around the first and second supply wires.

13. A method as claimed in claim 10, wherein pulling the lighting driver towards the stem portion using the first and second supply wires comprises pulling the lighting driver to slide relative to the first wire and the second wire along a shape feature of the lighting driver.

14. A method as claimed in claim 10, further comprising connecting the lighting driver to the first and second wires by soldering before hermetically connecting the stem portion to the opening of the envelope.

15. A method as claimed in claim 11, further comprising connecting the LED arrangement between the first wire and the second wire before hermetically connecting the stem portion to the opening of the envelope.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0052] For a better understanding of the invention, and to show more clearly how it may be carried into effect, reference will now be made, by way of example only, to the accompanying drawings, in which:

[0053] FIG. 1 shows a known LED bulb;

[0054] FIG. 2 shows a bulb in accordance with an example of the invention;

[0055] FIG. 3 shows the stem portion and connected wires and tubes;

[0056] FIG. 4 shows the lighting driver mounted over the first wire;

[0057] FIG. 5 shows the lighting driver mounted further down over both the first wire and the second wire;

[0058] FIG. 6 shows the assembly of FIG. 5 inserted into the bulb envelope;

[0059] FIG. 7 shows how the supply wires are pulled to move the lighting driver towards the stem portion;

[0060] FIG. 8 shows the electrical connections in more detail;

[0061] FIG. 9 shows an alternative design for the electrical connections; and

[0062] FIG. 10 shows a method of manufacturing a LED lighting bulb.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0063] The invention will be described with reference to the Figures.

[0064] It should be understood that the detailed description and specific examples, while indicating exemplary embodiments of the apparatus, systems and methods, are intended for purposes of illustration only and are not intended to limit the scope of the invention. These and other features, aspects, and advantages of the apparatus, systems and methods of the present invention will become better understood from the following description, appended claims, and accompanying drawings. It should be understood that the Figures are merely schematic and are not drawn to scale. It should also be understood that the same reference numerals are used throughout the Figures to indicate the same or similar parts.

[0065] The invention provides a LED lighting bulb in which a lighting driver is located within the bulb envelope. During assembly, the lighting driver may be positioned away from an opening of the envelope so that high temperature sealing of a stem portion of the end cap to the envelope opening can take place. The lighting driver can then be pulled into position against the stem portion, and assembly of the end cap can then be completed.

[0066] FIG. 1 shows a known LED bulb 10 comprising an envelope 12 having an opening 14. An end cap 16 is at the opening. The end cap defines the external electrical connector for connection to a bulb holder.

[0067] Within the volume of the end cap 16 is a lighting driver. To make space for the lighting driver in the end cap volume, outside the envelope 12 of the bulb, the end cap comprises a standard connector part 16a (such as a screw fitting as shown) and also an additional volume 16b.

[0068] As this additional volume 16b is normally enclosed by a non-transparent material, such as a metal/plastic over-molding housing, it changes the appearance of the bulb and may not be desired. It would be preferred to enable the connector to be as small as possible and to house the lighting driver in the envelope.

[0069] FIG. 2 shows a bulb in accordance with an example of the invention. The LED bulb 10 again comprising an envelope 12 in a bulbous shape, for example of glass, having an opening 14, and an end cap 16 at the opening.

[0070] The end cap 16 has an electrical connector part 40 with a first terminal 18 and a second terminal 20 for making electrical connection with a bulb holder.

[0071] The end cap further comprises a stem portion 22 which closes the opening in the envelope. A first wire 24 and a second wire 26 extend from the stem portion 22 into the envelope. The stem portion is the part that closes and therefore seals the envelope volume. It is also a glass component. Note that for the purposes of this description, the stem portion is considered to be part of the end cap. It could equally be considered to be a separate part to which the end cap connects.

[0072] The lighting driver 28 is positioned at an envelope side of the stem portion 22, namely within the envelope volume. The lighting driver 28 comprises a shape feature (described further below) for allowing the lighting driver to slide relative to the first wire 24 and the second wire 26, and the lighting driver 28 is electrically connected to the first wire and the second wire.

[0073] This shape feature allows the lighting driver to be located further towards the center of the envelope volume when the stem portion 22 is connected to the envelope. The lighting driver can then be pulled back to the stem portion.

[0074] An LED filament 42 is provided between the first wire and the second wire. This takes the form of one or more light emitting strips.

[0075] The bulb thus has the lighting driver on the envelope side of the stem portion of the end cap, i.e. within the bulb envelope. To protect the lighting driver during assembly, for example during sintering of the envelope to the stem portion (to seal the envelope), the lighting driver is slideable along the first and second wires.

[0076] The parts of the design of FIG. 2, and the way the assembly takes place, will be described with reference to FIGS. 3 to 9.

[0077] FIG. 3 shows the stem portion 22, with the first wire 24 and second wire 26 projecting from a first side, in particular the envelope side (i.e. the side or end of the stem portion 22 which faces into the envelope volume when the bulb is assembled). The opposite side of the stem portion may be considered to be an end cap side.

[0078] Extending from the end cap side is a tube arrangement 34 comprising a first glass tube 34a and a second glass tube 34b.

[0079] FIG. 4 shows the lighting driver 28 mounted over the first wire 24. In FIG. 4 it is shown initially mounted over the first wire 24, but it is then slid down until it also passes over the second wire 26.

[0080] The lighting driver comprises a circuit board 28a and components 28b mounted on the circuit board 28a. A driver output anode cable 27a and a driver output cathode cable 27b extend from the circuit board 28a for soldering with the first wire 24 and second wire 26 respectively to provide the electrical output connections from the driver.

[0081] A shape feature is provided for allowing the lighting driver to slide relative to the first wire 24 and the second wire 26. This shape feature for example comprises a pair of openings, one opening 30 of which can be seen in FIG. 4 which will slide over the second wire 26 when the lighting driver 28 is lowered further towards the stem portion 22.

[0082] It is noted that the openings (such as opening 30) may instead be radially opening slots.

[0083] A first supply wire 36 extends from the lighting driver 28, through a first opening 23a in the stem portion 22 and through the first tube 34a. A second supply wire 38 extends from the lighting driver 28, through a second opening 23b in the stem portion 22 and through the second tube 34b. The first and second supply wires make electrical contact with input terminals of the lighting driver.

[0084] The first supply wire 36 is for making electrical connection between the first terminal 18 and a first input terminal of the lighting driver through the first tube 34a and through the stem portion 22; and the second supply wire 38 is for making electrical connection between the second terminal 20 and a second input terminal of the lighting driver 28 through the second tube 34b and through the stem portion.

[0085] FIG. 5 shows the lighting driver 28 mounted over both the first wire 24 and the second wire 26. The LED string 42 can then be connected between the first wire and second wire.

[0086] Furthermore, the driver output anode cable 27a connects to the first wire at location 29a and the driver output cathode cable 27b connects to the second wire at location 29b. This is by for example soldering. As shown in FIG. 5, there is slack in the cables 27a, 27b so that the driver 28 is free to slide towards the stem portion, which will result in straightening of the cables 27a, 27b.

[0087] FIG. 6 shows that the assembly of FIG. 5 is then inserted into the bulb envelope 12. The stem portion closes the opening of the envelope. A sintering process is then used to seal the stem portion to the envelope.

[0088] During this sintering process, the lighting driver 28 is positioned spaced apart from the stem portion, as shown. Thus, it is not in contact with the stem portion, but there is an air gap between them. This prevents direct thermal conduction to the lighting driver 28 and protects the lighting driver from the sintering temperature. The spacing is for example more than 5 mm, for example more than 1 cm.

[0089] FIG. 7 shows how the supply wires 36, 38 are then pulled to move the lighting driver 28 towards the stem portion 22, preferably until it makes contact with the stem portion 22. The driver output anode cable 27a and the driver output cathode cable 27b are straightened during this process.

[0090] As shown most clearly in FIG. 8, the first supply wire 36 is then is sealed within the first tube 34a and the second supply wire 38 is sealed within the second tube 34b. This is a further sintering process.

[0091] This process provides a hermetic seal to the interior volume of the envelope (and the seal between the stem portion 22 and the opening is also hermetic). The tubes may be used to evacuate the envelope volume or to provide a gas such as a gas with a high coefficient of thermal conductivity and low viscosity. Helium or hydrogen or a mixture thereof may be used, and this can reduce the heat sink requirements.

[0092] FIG. 8 shows more clearly the electrical connections and shows that the driver inputs 36 and 38 contact with the end cap, whereas the driver output cables 27a and 27b are soldered to the first wire 24 and the second wire 26 at soldering points 29a and 29b.

[0093] The end cap 16 is then assembled. This involves connecting the first supply wire 36 to the first terminal 18 and connecting the second supply wire 38 to the second terminal 20, as shown. The end cap is thereby assembled, by coupling the stem portion 22 and the terminal portion 40.

[0094] FIG. 9 shows an alternative electrical connection arrangement. The first and second wires 24, 26 each comprise a respective enlarged foot portion 24a, 26a. The PCB 28a of the lighting driver 28 comprises conductive vias as the openings 30. When the lighting driver 28 is fully retracted to abut against the stem portion 22, the enlarged foot portions 24a, 26a make electrical contact and frictional engagement with the conductive vias. Thus the output of the lighting driver is connected to the first wire and second wire for driving the LED filament in an automatic way without needing additional soldered wires. The other features are the same as in FIG. 8.

[0095] Any other electrical contact design may be used by which the movement of the lighting driver 28 into its final position results in an electrical connection being made between the lighting driver output terminals and the first and second wires. Also, instead of soldered connection wires, other types of electrical connections may be made such as using electrical connectors.

[0096] FIG. 10 shows a method of manufacturing a LED lighting bulb.

[0097] In step 50, an envelope is provided having an opening.

[0098] In step 52, a stem portion of an end cap is provided, having a first wire and a second wire extending from the stem portion (shown in FIG. 3). A pair of tubes also extend back from the stem portion on the opposite side to the first and second wires.

[0099] In step 54, a lighting driver is mounted along the first wire and second wire (shown in FIG. 4). The lighting driver comprises first and second supply wires which extend through the stem portion and each through a respective one of the tubes.

[0100] In step 56, an LED arrangement is connected between the first wire and the second wire and, for the design of FIG. 8, soldered electrical connections are made between the first wire and second wire and the driver output cables.

[0101] In step 58, the stem portion is hermetically connected to the opening of the envelope with the lighting driver remote from the stem portion and within the envelope (shown in FIG. 6), preferably by sintering.

[0102] In step 60, the lighting driver is pulled towards the stem portion along the first and second wires using the first and second supply wires (shown in FIG. 7). For the design of FIG. 9, this step 60 creates the electrical connections between the first wire and second wire and the driver outputs.

[0103] In step 62, the envelope is optionally evacuated or filled with a gas.

[0104] In step 64, the tubes are sealed around the first and second supply wires, preferably by sintering.

[0105] In step 66, the end cap is assembled by connecting the first and second supply wires to first and second terminals of the terminal portion of the end cap and connecting the terminal portion to the stem portion.

[0106] The example above is based on one envelope shape and one end cap design. The invention may of course be applied to other designs. The LED arrangement may take any desired form with a single color or a controllable color, and the invention can be applied to any type of driver. There may be additional circuit components in the end cap or as part of the lighting driver, such as sensors, or RF communications circuits to enable remote wireless control. Thus, the invention may be applied to a variety of bulb types.

[0107] Variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure and the appended claims. In the claims, the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality. Any reference signs in the claims should not be construed as limiting the scope.