EP0451908A1

EP0451908A1 - Electric lamp

Info

Publication number: EP0451908A1
Application number: EP91200794A
Authority: EP
Inventors: Livio Borgis; Marco Vicenzo Pietro Piacibello; Cornelis Penning
Original assignee: Philips Gloeilampenfabrieken NV; Koninklijke Philips Electronics NV
Current assignee: Koninklijke Philips NV
Priority date: 1990-04-09
Filing date: 1991-04-05
Publication date: 1991-10-16
Also published as: JPH04230952A; HU911123D0; HUT57476A

Abstract

The electric lamp has a tubular insulator body (5),
fitted in and extending from a stemtube (3) of the lamp vessel (1). The insulator body (5) has a longitudinal cavity (7) and first (10) and second (11) radial projections. The first projections each bear a respective contact element (8) to which current supply conductors (9) extend via the central vavity (7) from an electric element (4)
mounted within the lamp vessel (1).
The lamp of the invention is of a simple construction and can readily be mounted into a simple holder. The lamp is suitable for use in electrical domestic appliances.

Description

The invention relates to an electric lamp provided with

a translucent lamp vessel having an end portion where a stemtube fused to the lamp vessel projects into the lamp vessel,
an electric element in the lamp vessel,
a tubular insulator body having a longitudinal direction and a longitudinal cavity, fixed in the stemtube and project therefrom to the exterior,
contact elements fastened to the insulator body,
current supply conductors connected to the electric element, extending to respective contact elements and fastened thereto, at least one current supply conductor extending through the cavity of the insulator body.

Such an electric lamp is known from DE 462.796.
In the known incandescent lamp, the insulator body is fixed with its portion projecting from the stemtube in a threaded metal shell, forming a first contact element, and carries at an end surface a metal plate by way of a second contact element. The insulator body thus forms the geometry of an Edison lamp cap in conjunction with these contact elements. The insulator body consists of glass or ceramic material and is secured in the stemtube with cement.
The object of the construction of this known lamp is to render possible the use of a smaller lamp cap than in the case in which a lamp cap is used which grips around the end portion of the lamp vessel. Another object of this construction is to provide a safe lamp in which no live metal parts can be touched. The construction, however, does not offer this safety since the lamp can be inserted in a lampholder whose screwthread is under electrical tension, thus rendering the threaded metal shell at the lamp live. In addition, one current supply conductor runs along the outside of the insulator body towards the threaded shell.
For some applications, such as in electrical appliances, such as, for example, domestic appliances like ovens, microwave ovens, refrigerators and freezers, sewing machines, etc, the construction of the known lamp is expensive, also because the lamp requires an expensive lampholder and inserting of the lamp in the lampholder and mounting and connecting the lampholder in the appliance requires much time.
The invention has for its object to provide an electric lamp of the kind described in the opening paragraph which, inter alia, is of a simple, easily manufactured construction and which can be easily inserted in a holder.
According to the invention, this object is achieved in that the insulator body has, outside the stemtube, first diametrically opposed, radial projections which carry respective contact elements and second diametrically opposed radial projections closer to the lamp vessel than the first projections, the two current supply conductors extending through the longitudinal cavity to the contact elements.
The lamp according to the invention is of a simple construction and can be easily inserted in a holder. This holder may consist of a wall, for example a wall of an electrical appliance, provided with an opening which just allows the first projections to pass. If the lamp is then rotated about the longitudinal direction of the insulator body, the said wall can be included between the first and the second projections, so that the lamp is securely held.
The lamp is safe to touch since the current supply conductors run through the longitudinal cavity. The contact elements, moreover, do not come into contact with contact members until behind the wall of a holder.
For lamp operation in conditions in which the contact elements are exposed to corrosive influences, it is possible to fasten electrical cables to the contact elements, for example by welding or soldering, so that connections with a supply source can be achieved at a distance from the lamp. The holder of the lamp is very simple in that case.
Alternatively, the holder may be provided with contact members which come into contact with respective contact elements when the lamp is inserted in the holder and rotated about the longitudinal direction of the insulator body. An attractive aspect of the lamp acording to the
invention is that the lamp vessel and the stemtube fused thereto as well as the other parts present in the lamp vessel, such as the electric element, current supply conductors and possible additional mounting means for the electric element, are allowed to be of a conventional shape and construction. This means that the lamp can be manufactured on conventional machines and lamps manufactured in this way can be given conventional lamp caps, as required, for applications in which such a conventional lamp cap is required.
In a favourable embodiment of the lamp according to the invention, the contact elements are fixed in a cavity in the first projections. They are then securely anchored to the insulator body. The contact elements may be included in the cavity with clamping fit and/or be fixed in the cavities by a deformation of a portion of said elements.
For fast and easy mounting and for a reliable
electrical connection between the current supply conductors and the contact elements it is favourable for the contact elements to have a split portion which forms a piercing contact with a current supply conductor. The current supply conductor is then held clamped in by that split portion. The electrical resistance of such a connection is very low and to a high degree independent of corrosive influences.
In an embodiment which is favourable for the mechanical stability of the lamp in a holder, the second projections have a position which is rotated through 90^o relative to the first
projections about the longitudinal direction of the insulator body. In another favourable embodiment, the second projections together form a continuous flange around the insulator body. Such a flange is capable of completely covering the opening in a wall through which the first projections have been inserted. It is thus made impossible to touch contact elements with a thin object through the opening of the holder when a lamp has been inserted into a holder.
In a favourable embodiment, the insulator body has a longitudinal partition wall in the central cavity, near its end facing away from the lamp vessel. It is favourable if the partition wall becomes thicker towards that end. The current supply conductors are then easily led to the exterior in a defined spot in order to be connected to the contact elements when the insulator body is mounted.
The insulator body may be made of glass, ceramic
material, or synthetic resin, for example from thermoplastic synthetic resin such as polyphenylene sulphide, polyether imide,
polyether sulphon. The insulator body may be fixed in the stemtube in that the current supply conductors are connected to the contact elements with mechanical tension. Alternatively, lamp cement or a synthetic resin may be used, such as, for example, silicone resin, epoxy resin, or the insulator body itself may adhere to the stemtube.
Embodiments of the lamp according to the invention are shown in the drawing, in which

Fig. 1 is a first embodiment, partly in side elevation, partly in axial cross-section,
Figs. 2-4 show alternative embodiments of the free end of the insulator body comprising contact elements, in perspective view,
Fig. 5 shows a holder for a lamp of Fig. 1 in perspective view,
Fig. 6 shows an alternative embodiment of a holder with a mounted lamp, in perspective view.

In Fig. 1, the electric lamp has a translucent lamp vessel 1 with an end portion 2 where a stemtube 3 fused to the lamp vessel projects into the lamp vessel. An electric element 4, an incandescent body in the Figure, but in an alternative lamp, for example, a pair of electrodes, is positioned in the lamp vessel. A tubular insulator body 5, for example made of polyphenylene sulphide, which has a longitudinal direction 6 and a longitudinal cavity 7, is fixed in the stemtube 3, for example with an adhesive such as silicone cement, and projects therefrom to the exterior. Contact elements 8 are fastened to the insulator body 5. Current supply conductors 9 are connected to the electric element 4, extend to respective contact elements 8, and are fastened thereto. At least one of these current supply conductors 9 runs through the longitudinal cavity 7.
The insulator body 5 has, outside the stemtube 3, first diametrically opposed radial projections 10 which carry respective contact elements 8 and second, diametrically opposed radial projections 11 closer to the lamp vessel 1 than the first projections 10. Both current supply conductors 9 extend through the longitudinal cavity 7 to the contact elements 8.
The contact elements 8 are fixed in a cavity 13 in the
first projections 10 (see also Figs. 2-4). A longitudinal partition wall 12 is present in the longitudinal cavity 7 near the end facing away from the lamp vessel 1, which wall becomes thicker towards this end.
The second projections 11 together form a continuous
flange around the insulator body.
In Figs. 2-4, corresponding parts have reference numerals which are 20 higher each time than those in the immediately preceding Figure.
In Fig. 2, insulator body 25 has second projections 31
which have a position rotated through 90^o relative to the projections 30. The projections 30 have cavities 33 for contact elements 28, 28'.
A current supply conductor 29 issues in straight shape
from the insulator body 25 to the exterior. Contact element 28' can be passed into a cavity 33. A tag 34' on the element may be bent
after insertion by way of extra fixation (compare Fig. 1).
The current supply conductor 29 may now be radially bent
and pulled into the split portion 35' of the contact element in order to be clamped in there. A lamp having two such contact elements 28' is suitable for use in a holder as shown in Fig. 5.
Fig. 2 also shows an embodiment which is provided with a contact element 28 which is suitable for being connected to a cable 28a e.g. by welding or soldering. The portion of contact member 28 included in the cavity 33 is identical to contact member 28'. In a lamp having two contact elements 28 with cables 28a mounted to them, the electrical supply can be connected to a supply source at a distance from the location where the lamp is mechanically held.
In Figs. 3 and 4, again, two contact elements of
different kinds are shown each time. In contrast to the lamp of Fig. 2, the lamps of Figs. 3 and 4 are obtained in that first the current supply conductors 49, 69 are put in their positions in the cavities 53, 73, respectively, by bending them, followed by the contact elements 48, 48' and 68, 68', respectively. The electrical connections between the current supply conductors and the contact elements are effected during that same operation.
In Fig. 5, the holder has a housing 80 with a wall 81 comprising an opening 82 for allowing the first projections 10 and the contact elements 8 of the lamp of Fig. 1 to pass. The housing 80 contains contact members 83 which can make contact with respective contact elements 8 from Fig. 1 and which also form insert contacts for cables 84 extending to an electrical supply. The housing comprises a stop 85 against which a projection 10 (Fig. 1) is checked in the final position of the lamp, and an elevation 86 over which a projection 10 is rotated with friction when the lamp is inserted in order to fix the lamp in its final position. Hooks 87 serve to fasten the holder to a wall having openings designed for these hooks. The housing may be closed with a wall through which cables 84 are passed.
In Fig. 6, the holder shown has a housing 90 with
mounting hooks 97 and an elevation 96 analogous to 86 in Fig. 5. A lamp having an insulator body 25 of Fig. 2 is inserted in the holder. Cables 28a soldered to the contact elements 28 connect the lamp to a supply source. The holder may alternatively consist of a flat wall 91 provided with an opening for accommodating the insulator body, possibly provided with fastening means, such as hooks 97, and stamped or cast elevations serving as stops or fixation means for the lamp.

Claims

An electric lamp provided with
- a translucent lamp vessel (1) having an end portion (2) where a stemtube (3) fused to the lamp vessel projects into the lamp vessel,

- an electric element (4) in the lamp vessel,

- a tubular insulator body (5) having a longitudinal direction (6) and a longitudinal cavity (7), fixed in the stemtube (3), and project therefrom to the exterior,

- contact elements (8) fastened to the insulator body (5),

- current supply conductors (9) connected to the electric element (4), extending to respective contact elements (8) and fastened thereto, at least one current supply conductor (9) extending through the cavity (7) of the insulator body (5),
characterized in that the insulator body (5) has, outside the stemtube (3), first diametrically opposed, radial projections (10) which carry respective contact elements (8) and second diametrically opposed radial projections (11) closer to the lamp vessel (1) than the first projections (10), the two current supply conductors (9) extending through the longitudinal cavity (7) to the contact elements (8).
An electric lamp as claimed in Claim 1, characterized in that the contact elements (8) are fixed in cavities (13) in the first projections (10).
An electric lamp as claimed in Claim 1 or 2, characterized in that the contact elements (28', 48, 68) have split portions (35', 55, 75) which keep respective current supply conductors (49, 69) clamped in, acting as piercing contacts.
An electric lamp as claimed in Claim 1 or 2, characterized in that a cable (28a) is mounted to the contact elements (28, 48, 68).
An electric lamp as claimed in Claim 1, 2 or 3, characterized in that the second projections (31, 51, 71) are rotated through 90^o about the longitudinal direction of the insulator body (25, 45, 65) relative to the first projections (30, 50, 70).
An electric lamp as claimed in Claim 1, 2 or 3, characterized in that the second projections (11) together form a continuous flange around the insulator body (5).
An electric lamp as claimed in Claim 1, 2 or 3, characterized in that the insulator body (5) has a longitudinal partition wall (12) in the longitudinal cavity (7) near its end facing away from the lamp vessel (1).
An electric lamp as claimed in Claim 7, characterized in that the partition wall (12) becomes thicker towards the end facing away from the lamp vessel (1).