Luminaire for installation in an electrical household appliance

Abstract

A luminaire for installation in an electrical household appliance, e.g. a washing machine, includes, in one embodiment, two light-emitting diodes mounted on a circuit board, an elongated luminaire housing having a light exit area, which is formed by a light-permeable piece of the housing wall, in an area of a first longitudinal end of the luminaire housing, and also a light-conducting body having a light-conducting tube which extends inside the luminaire housing and which conducts, towards the light exit area, light which is given off by the light-emitting diodes. In one embodiment, a metalizing layer provided on the inner peripheral face of the light-conducting tube rests, in heat-transmitting contact with one or more conductive traces, on the upper side of the circuit board. In addition to its light-conducting function, the light-conducting tube thus fulfills a function for discharging heat from the circuit board.

Claims

1. A luminaire for installation in an electrical household appliance, the luminaire comprising: a light-source arrangement; an elongated luminaire housing having a substantially cylindrical wall with a light-permeable convex piece formed at a first longitudinal end of the luminaire housing, which convex piece defines a light exit area in the region of the first longitudinal end of the luminaire housing; a light-conducting body forming a tubular light-conducting tube wherein the light-conducting body extends inside the luminaire housing to a position adjacent the convex piece and which conducts, towards the light exit area, light emitted from the light-source arrangement; and a circuit board, the light-source arrangement being mounted on the circuit board, wherein the light-conducting tube projects above the circuit board with a tube axis perpendicular to the plane of the circuit board, wherein the light-conducting tube includes a metal material in heat-transmitting contact with at least one conductive trace of the circuit board, the metal material extending along at least part of a tube length of the light-conducting tube, wherein the light-conducting tube has an axial end face which is adjacent the circuit board, the metal material extending as far as the axial end face, wherein the heat-transmitting contact of the metal material with the at least one conductive trace is established at the axial end face.

2. The luminaire of claim 1 wherein the light-conducting tube has an inner peripheral face, wherein at least a portion of the inner peripheral face is formed of the metal material.

3. The luminaire of claim 2 wherein the light-conducting tube has a tubular wall which is formed from a plastic material and which is provided, on an inner periphery, with a metal coating.

4. The luminaire of claim 1 wherein the end portion of the light-conducting tube extends beyond an end of the substantially cylindrical wall of the luminaire housing and adjacent the light exit area of the convex piece.

5. The luminaire of claim 1 wherein the light-source arrangement includes at least one light-emitting diode.

6. The luminaire of claim 1 wherein the light-source arrangement includes two light-emitting diodes having different emission spectra.

7. The luminaire of claim 1 wherein the light-conducting body has an end portion which is open in a pot-like manner and in which the circuit board is inserted, the end portion having a cross-section adapted to the circuit board.

8. The luminaire of claim 1 wherein the light-conducting tube has a shape of a cylindrical tube.

9. The luminaire of claim 1 wherein the luminaire housing has a housing aperture in the area of a second longitudinal end and the light-conducting body is inserted in the luminaire housing through the housing aperture with the tubular light-conducting tube in front.

10. An electrical household appliance having an interior space and at least one luminaire for illuminating the interior space, the luminaire comprising: a light-source arrangement; an elongated luminaire housing having a substantially cylindrical wall with a light-permeable convex piece formed at a first longitudinal end of the luminaire housing, which convex piece defines a light exit area in the region of the first longitudinal end of the luminaire housing; a light-conducting body forming a tubular light-conducting tube wherein the light-conducting body extends inside the luminaire housing to a position adjacent the convex piece and which conducts, towards the light exit area, light emitted from the light-source arrangement; and a circuit board, the light-source arrangement being mounted on the circuit board, wherein the light-conducting tube projects above the circuit board with a tube axis perpendicular to the plane of the circuit board, wherein the light-conducting tube includes a metal material in heat-transmitting contact with at least one conductive trace of the circuit board, the metal material extending along at least part of a tube length of the light-conducting tube, wherein the light-conducting tube has an axial end face which is adjacent the circuit board, the metal material extending as far as the axial end face, wherein the heat-transmitting contact of the metal material with the at least one conductive trace is established at the axial end face.

11. The electrical household appliance of claim 10 wherein the appliance is a washing machine and the luminaire is mounted in a door seal of the washing machine.

12. The electrical household appliance of claim 10 wherein the appliance is an oven.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 represents a sectional representation through a luminaire according to one example of embodiment.

(2) FIG. 2 represents a detail of FIG. 1 in an enlarged representation.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

(3) The luminaire shown in FIG. 1 is designated generally by 10. It has a luminaire housing 12 produced from a transparent plastic material, a light-conducting body 14 and an electronics plate (circuit board) 16, on which there are mounted a plurality of light-emitting diodes 18 and also, optionally, other electrical parts. In the case of the example shown, a total of two light-emitting diodes 18 can be seen on the circuit board 16. These emit light within different wave ranges, so that an impression of white light is produced when the light from the two light-emitting diodes 18 is mixed. For example, one of the light-emitting diodes 18 emits light within a blue wave range, while the other of the light-emitting diodes 18 emits light within a yellow or yellow/orange wave range.

(4) The light-conducting body 14 forms a light-conducting tube 20 having an axis 22. The light-conducting tube 20 rests on the circuit board 16, with its axis 22 extending perpendicularly to the plane of the circuit board 16. The two light-emitting diodes 18 are located inside the light-conducting tube 20. On its inner peripheral facewhich is designated by 24the light-conducting tube 20 is provided with a metalizing layer 26 consisting, for example, of aluminum or silver, which is applied, for example in a vaporization process, to a base body 28 of the light-conducting body 14, which base body is produced from a plastic material. In the figures, the metalizing layer 26 is indicated diagrammatically by a line of increased thickness. It extends over the entire length of the tube on the inner peripheral face 24 and over the entire inner periphery of the light-conducting tube 20, and also extends as far as an end face 30 which is adjacent to the circuit board 16 and adjoins the inner peripheral face 24 and by means of which the light-conducting tube 20 rests on one or more metallic conductive traceswhich are indicated at 32. The metalizing layer 26 is in heat-transmitting contact, which may be assisted, for example, by a soldered joint or an adhesive capable of conducting heat, with these conductive traces 32 (or/and with tinned soldered points). The circuit board 16 may therefore be fixedly connected to the metalizing layer 26 and, as a result, to the light-conducting body 14 by a soldered joint or by an adhesive of this kind which is applied to the conductive traces 32. Alternatively, it is possible for the light-conducting body 14 to merely rest, with its metalizing layer 26, on one or more metallic components of the circuit board 16 (e.g. soldering lugs), without being fixedly connected to the circuit board 16.

(5) The metalizing layer 26 brings about reflections of the light emitted by the light-emitting diodes 18 inside the light-conducting tube 20, as indicated by arrows 34 in broken lines in FIG. 1. At the same time, part of the light emitted by the light-emitting diodes 18 passes through the light-conducting tube 20 without being reflected, as indicated by arrows 36 in broken lines in FIG. 1. In the area of that end of the tube which is axially remote from the light-emitting diodes 18, the light-conducting tube 20 is closed by a piece 38 of the end wall which is a constituent part of the base body 28 but is devoid of the metalizing layer 26. The light which is conducted within the light-conducting tube 20 passes through this piece 38 of the end wall into the space between the piece 38 of the end wall and the luminaire housing 12. From there, the light passes out through a light exit area 40 which, in the case of the example shown, is formed by a convex piece 42 of the wall of the luminaire housing 12. Like the remaining part of the luminaire housing 12, the piece 42 of the housing wall is produced from a light-permeable plastic material.

(6) Adjacent to the convex piece 42 of the housing wall, the luminaire housing 12 has a mounting section 44 which extends axially and is substantially cylindrical and which is designed, on its outer periphery, with one or more projections 46 which are, for example, rib-like and which serve to position the luminaire housing 12, and with it the luminaire 10 as a whole, in an axially secure manner in an installation aperture which belongs to an electrical household appliance of which no further details are represented and in which the luminaire 10 is to be installed. The installation aperture mentioned may be provided, for example, in a door seal of a household washing machine, as indicated in WO 2011/012292 A1 in FIG. 4 or in DE 38 43 385 A1 in the latter's single FIGURE. The content of these publications is incorporated herein by reference.

(7) In the area of its opposite axial end from the piece 42 of the housing wall, the luminaire housing 12 is of open construction, i.e. has, at that point, a housing aperture 48 through which the light-conducting body 14 is inserted (with the light-conducting tube 20 in front) in the luminaire housing 12. The light-conducting body 14 possesses, distributed in the peripheral direction, a plurality of elastically deflectable latching tongues 50 which permit a latching connection between the luminaire housing 12 and the light-conducting body 14. At least some of the latching tongues 50 are able to engage, in a snapping manner, in corresponding latching recesses 52 belonging to the luminaire housing 12. By means of the latching tongues 50, the light-conducting body 14 is fixed in position axially, relative to the luminaire housing 12.

(8) For its part, the circuit board 16 is inserted in an end section 54, which is open in a pot-like manner, of the light-conducting body 14. This end section 54 possesses an aperture 56 of the pot which has a cross-sectional shape and size that correspond to the contour of the circuit board 16, so that the circuit board 16 is fixed in position radially (referred to the axis 22 of the tube) in the aperture 56 of the pot of the end section 54. The bottom of the pot of the end section 54 is defined by an axial end face 58 which may lie within the same axial plane as the end face 30 or may be slightly offset axially in relation thereto (as indicated in FIG. 2). The end face 58 delimits the axial depth of insertion of the circuit board 16 in the aperture 56 of the pot of the end section 54. Fastening of the circuit board 16 to the light-conducting body 14 may be brought about, for example by adhesion or screwing, in the area of the end face 58.

(9) As a result of the heat-conducting contact of the metalizing layer 26 with the conductive traces 32, discharge of the heat produced by the light-emitting diodes 18 and, optionally, other parts on the circuit board 16 is possible in the area of the light-conducting tube 20, so that overheating of the light-emitting diodes 18 and of the luminaire 10 as a whole can be avoided. In addition to its function for conducting light, the light-conducting tube 20 thereby also fulfils a function for dissipating heat, that is to say for cooling the circuit board 16 and the parts located thereon.

(10) Although the preferred embodiments of the present invention have been described herein, the above description is merely illustrative. Further modification of the invention herein disclosed will occur to those skilled in the respective arts and all such modifications are deemed to be within the scope of the invention as defined by the appended claims.