Lamp assembly

Abstract

 A lamp assembly comprises an electrically insulating hollow body (12), a plurality of bulbholders (16) and a plurality of spaced, electrically conductive elements (22), cut from an electrically conductive sheet (18). Each bulbholder (16) is provided with a contact blade (38) having a flat portion (42) extending parallel to and abutting said electrically conductive element (22). The flat portion (42) and the abutting part of the electrically conductive element (22) each having a formation whereby they are retained on the insulating body.

Description

[0001] This invention relates to a lamp assembly and a method of manufacture thereof.

[0002] A lamp assembly is known (see German Auslegeschrift No. 2441330) in which a hollow electrically insulating body supports a plurality of spaced electrically conductive elements which extend from a location at which an electrical supply connector is connected with the elements in use, to respective bulbholder locations. Holes are formed in one of the conductive elements and separately moulded plastics bulbholders are engaged with a snapfit action into the holes. Portions of the respective electrically conductive elements in the region of the electrical supply location are shaped to provide blade terminals for connection with female terminals in the supply connector. Other portions of the electrically conductive elements are shaped to provide contacts which are electrically connected to respective bulb contact blades carried by the bulbholders. The electrically conductive elements are all formed from the same sheet metal blank by piercing the blank to define the electrically conductive portions but leaving parts of the sheet metal unpierced so that the electrically conductive elements are held in the required relative dispositions by the integral joining parts. Then the portions of the electrically conductive elements which are to form the terminals and the contacts are simply bent out of the plane of the sheet to define the terminals and the contacts. At this stage, the sheet, having previously had the sub-assembly of bulbholders and bulb contacts to be carried thereby snap-fitted thereto, is mounted in a die and the joining parts are then removed whilst maintaining the electrically conductive elements and the bulbholders in the required dispositions. The hollow electrically insulating body is inserted into the die so that spigots on the free ends of supports extending integrally from an internal surface of the base of the body extend through holes in the respective conductor elements. The spigots are subsequently deformed over by a heating tool to retain the conductive elements in position. Finally, a moulding including a bulb reflector is fixed in position on the body on the opposite side of the electrically conductive elements to the base of the body and a composite lens element is fitted over said bulb reflector moulding to complete the lamp assembly.

[0003] In the above construction, the portions of the electrically conductive elements to be engaged by parts of the bulb contact blades are bent out of the general plane of the elements to define contact blades which engage in portions of the bulb contact blades which project externally of the bulbholders. Each of these portions of the bulb contact blades is produced by bending an end portion of the blade back on itself to double the thickness of the blade and cutting a slot in the doubled-over portion. The slot has a width which is marginally less than the thickness of the sheet from which the elements and the contact blades integral therewith are formed. The contact blades integral with the elements are engaged in the respective slots so that the plane of each contact blade is at right angles to the plane of the respective slotted portion of the bulb contact blade. This construction only gives a limited contact area.

[0004] An object of the present invention is to obviate or mitigate such problems by improving the electrical contact while simplifying the construction of the contact blades and installation of the conductive elements.

[0005] According to the invention a lamp assembly comprises an electrically insulating hollow body, a plurality of bulbholders, a plurality of spaced, electrically conductive elements, cut from an electrically conductive sheet and extending between a location in the body at which an electric supply connector is attached to the assembly in use and respective locations in the body adjacent to a bulbholder, at least one contact blade for each bulbholder in electrical connection with a respective one of the electrically conductive elements, each contact blade having a flat portion externally of the bulbholder and a blade portion within the bulbholder, the flat portion extending parallel to and abutting said electrically conductive element, said flat portion and the abutting part of said electrically conductive element each having a formation whereby they are retained on the insulating body.

[0006] The insulating body may have a respective projection for securing each blade contact and its associated electrically conductive element thereto, with the formations on such blade contact and electrically conductive element each comprising an aperture through which the projection extends, the formation on the one of said blade and said electrically conductive element further from theinsulating body comprising barbs adapted to engage with said formation to resist withdrawal.

[0007] The electrical connection between each contact blade and its respective electrically conductive element may be formed by a second blade portion which extends from the flat portion of the contact blade at an angle thereto and engages with a corresponding blade portion similarly extending from the electrically conductive element. Recesses may be provided in the insulating body for accommodating each such second blade portion and corresponding blade portion, one of which is resiliently biased to press against the other blade portion which, in turn, is pressed against a wall of the recess.

[0008] An embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings, in which:

Figure 1 is a plan view of electrically conductive elements in the relative dispositions which they occupy in a lamp assembly according to the invention;

Figure 2 is a cross sectional view of a part of a lamp assembly taken on the line 2 - 2 in Figure 1; and

Figure 3 is a fragmentary exploded perspective view illustrating the bulbholder shown in Figure 2.

[0009] Referring to the drawings, the lamp assembly comprises an electrically insulating, hollow moulded plastics body 10 (only partially shown in the drawings) which is of generally dish form having a rectangular base 12 and upstanding walls 14. Integrally moulded with the base 12 are five tubular elements 16 each constituting the electrically insulating part of a respective bulbholder.

[0010] Extending over the otherwise open face of the base 12 are six electrically conductive elements 18 to 23 all formed from the same mild steel sheet as described in the above mentioned German Auslegeschrift. Briefly the sheet is pierced to define the electrically conductive elements 18 to 23 but leaving parts 24 of the sheet metal unpierced so that the electrically conductive elements are held in the required relative dispositions. After the pierced blank has been inserted in a die, the joining parts are removed and the plastics body 10 is offered up to the die so that the electrically conductive elements are retained in position thereon in a manner to be described hereinafter.

[0011] The electrically conductive element 18, which serves as a common return path for all five bulbs, has a respective opening 26 aligned with each of the tubular portions 16. As can best be seen from Figure 3, upturned portions 28 and 30 are disposed at diametrically opposite locations on the edge of each opening 26 and each contains ' a respective opening 32 for receiving the lateral pins 34 (Figure 2) of the bayonet cap of a bulb 36.

[0012] Associated with each tubular portion 16 is a respective spring contact blade 38 having a first blade portion 40 within the tubular portion 16 and engaging with the centre contact of the bulb 36. Each contact blade also has a flat intermediate portion 42 and a second blade portion 44 which extends into a rectangular recess 46 disposed adjacent to the corresponding tubular recess 16. A rectangular opening is formed in the flat portion 42 in order to accommodate a spigot 48 which is moulded integrally with the plastics base 12.

[0013] During assembly, the contact blades 38 are positioned on the plastics body 10 before it is offered up to the die containing the electrically conductive elements 18 to 23. Each such element has at least one rectangular aperture, such as the aperture 50 in the element 22, provided with inwardly directed barbed projections 52 and 54 which engage with opposite sides of the spigot 48. Adjacent to the aperture 50, a tongue 56 is stamped out of the element 18 and bent downwards so as to be insertable into the recess 46 where it engages between one of the walls thereof and the contact portion 44. The engagement of the barbed portions 52 and 54 with the spigot 48 not only serve to retain the conductive element 22 in position but also enable it to hold the contact blade 42 in place as can be seen in Figure 3, a second spigot 58 is formed on the base 12. The spigot 58 is engaged by barbed projections 60 and 62 formed on the edges of an opening 64 in the conductive element 18.

[0014] Similar arrangements of spigots and barbed projections are provided at each of the other bulbholders, at the other ends of each of the conductive strips to which electrical connections are made and at such intermediate locations as are necessary to give the conductor strips the required rigidity.

[0015] It will be appreciated that the invention can be used in a lamp assembly having a different number of bulbholders from that described above.

Claims

1. A lamp assembly comprising an electrically insulating hollow body (10), a plurality of bulbholders (16), a plurality of spaced, electrically conductive elements (19-23), cut from an electrically conductive sheet (18) and extending between a location in the body (10) at which an electric supply connector is attached to the assembly in use and respective locations in the body adjacent to a bulbholder (16), at least one contact blade (38) for each bulbholder in electrical connection with a respective one of the electrically conductive elements (19-23), each contact blade (38) having a blade portion (40) within the bulbholder (16), characterised in that each contact blade (38) has a flat portion (42) externally of the bulbholder (16) extending parallel to and abutting said electrically conductive element (23), said flat portion (42) and the abutting part of said electrically conductive element (22) each having a formation whereby they are retained on the insulating body (10).

2. A lamp assembly according to claim 1, characterised in that the insulating body has a respective projection (48) for securing each blade contact (38) and its associated electrically conductive element (22) thereto, with the formations on such blade contact (38) and electrically conductive element each comprising an aperture through which the projection (48) extends, the formation on the one of said blade (38) and said electrically conductive element (22) further from the insulating body (10) comprising barbs (52, 54) adapted to engage with said formation (48) to resist withdrawal.

3. A lamp assembly according to claim 1 or 2, characterised in that the electrical connection between each contact blade (38) and its respective electrically conductive element (22) is formed by a second blade portion (44) which extends from the flat portion (42) of the contact blade (38) at an angle thereto and engages with a corresponding blade portion (56) similarly extending from the electrically conductive element (22).

4. A lamp assembly according to claim 3, characterised in that recesses (46) are provided in the insulating body (10) for accommodating each second blade portion (44) and corresponding blade portion (56), one of which is resiliently biased to press against the other blade portion which, in turn, is pressed against a wall of the recess (46).

Drawing