Switching device with integrated light source
The present invention relates to a switching device of the type comprising a casing delimiting a housing having a base provided externally with connection terminals for the electrical connection of the switching device, an operating member, a switching mechanism disposed in the casing, a light source carried by the said casing, and conductive areas for the connection of the light source, which areas are provided in the casing and are connected to connection terminals, the light source comprising an emitting portion remote from the base of the casing and at least two connection members extending at least partially through the said casing from the said emitting portion as far as at least two areas for the connection of the light source.
It is known to integrate a light source in a switching device in order for the light source to illuminate the control button fitted on the switching device.
A switching device of this type conventionally comprises, in the casing, one or a plurality of resiliently deformable plates which enable one or a plurality of electrical contacts to be established when they are displaced under the action of the operating member.
The switching device comprises, in the base of the casing, electrical connection terminals permitting connection to a printed circuit by welding.
In order to be visible from the operating region, the light source must be arranged on the side of the switching mechanism remote from the connection terminals.
In a switching device of this type, it is known to use, as the light source, a light-emitting diode with pins which comprises a transparent head from which two connection members project. The transparent head contains a ligh - emitting semiconductor element. During the manufacture of the light-emitting diode, one end of each connection member is connected to the light-emitting element and is then embedded in the transparent head.
Once, the connection members of the diode have been fitted in the switching device, they extend through the casing of the switching device. The free end of each member is connected to a conductive connection area provided on the base of the casing, that area being connected to a connection terminal for the supply of energy to the diode.
In practice, the internal region of the casing of the switching device is occupied by the switching mechanism so that the light-emitting diode projects from the casing on the side of the switching mechanism remote from the base of the casing.
The switching device is thus quite bulky in the direction of the height of the casing, considered from the base to the upper end of the diode.
The object of the invention is to propose a switching device which comprises a light source but is more compact in height .
For this purpose, the subject of the invention is a switching device of the above-mentioned type, characterized in that the said light source comprises an S C-type light- emitting diode formed by a body on one face of which at
least two flat, conductive and coplanar connection plates extend, and in that each connection member comprises a connection pin which is welded, at a first end, to a connection plate of the casing and is connected, at its second end, to a connection area of the casing.
According to specific embodiments, the switching device comprises one or a plurality of the following characteristics :
- each connection pin is ultrasound welded to the associated connection plate;
each pin comprises a main arm and a connecting foot extending perpendicularly relative to one another, the foot being welded bearing against the associated connection plate;
- each pin comprises a main arm which is extended, at its end remote from the light-emitting diode, by a tongue bent into the shape of a hairpin substantially along the main arm;
- the casing comprises at least two partitions which project into the housing of the casing from the base and between which the connection pins of the light source are held;
- the tongue of each pin comprises at least one locking tooth directed away from the main arm towards its free end, which tooth engages in one of the partitions in order to secure the light source;
- the light-emitting diode bears on the edge of at least one partition, and
- each connection area comprises a perforation through which the second end of the associated pin is engaged.
A further subject of the invention is a method for the manufacture of a switching device as defined above, characterized in that it comprises the following steps:
a) prefabricating a light source by ultrasound welding a connection pin to each flat conductive connection plate of an SMC-type light-emitting diode, and
b) assembling an operating member and a switching mechanism in a casing equipped with areas for the connection of the pins of the prefabricated light source.
The invention will be understood better from a reading of the following description which is given purely by way of example with reference to the drawings, in which:
Figure 1 is an exploded, perspective view of a switching device according to the invention,
Figures 2 and 3 are views sectioned in the planes P2-P2 and P3-P3 of the switching device, respectively,
Figure 4 is a perspective view of a first embodiment of a light source for the switching device of Figures 1 to 3, on an enlarged scale,
Figure 5 is a perspective view of the switching device according to the invention in perspective, from below, and
Figure 6 is a view, identical to that of Figure 4, of a variant of the light source according to the invention.
The switching device 10 shown in Figures 1 to 5 comprises a casing 12, an operating member 14 movable relative to the casing 12, a switching mechanism 16 housed in the casing 12, a light source 18, and a frame 20 for securing the operating member 14 and the switching mechanism 16 in the casing.
A transparent push-button, not shown, is fitted on the operating member 14, over the light source 18, to improve visual appearance and facilitate operation when the switching device is installed in an electronic apparatus, particularly a portable telephone.
The casing 12 is generally of parallelepipedal shape. It is made of insulating plastics material. It delimits internally a housing 22 of generally cylindrical shape, closed at one end by a base 24.
Six connection terminals 26A, 26B, 26C, 26D, 26E and 26F project laterally from either side of the base 24, in the plane thereof.
Four terminals 26A, 26C, 26D, 26F are connected to conductive areas 28 emerging inside the housing 22 in the vicinity of the base 24.
As is known per se, the switching mechanism 16 provided in the housing 22 comprises two superposed metal conductor plates 30.
These conductor plates are identical and generally have the shape of bell the top of which bears towards the base 24.
They have four radially-projecting arms suitable for cooperating with the areas 28 and thus ensuring an electrical contact. At rest, the arms normally extend away from the conductive areas 28. They are resiliently deformable in order to be brought into contact with the conductive areas 28 under the action of the operating member 14.
The operating member 14 generally has an annular shape defining an axial duct for receiving the light source 18. The operating member 14 can be displaced by sliding along the axis of the housing 22 between a conduction position in which the arms of the plates 30 are in contact with the conductive areas 28, putting the terminals 26A, 26C into communication with the terminals 26D, 26F, and a rest position as illustrated in Figures 2 and 3 in which the arms of the plates 30 are separated from the conductive areas 28.
The light source 18 is electrically connected for its energy supply to two conductive areas in the form of inserts 40 fixed firmly in the casing and connected to the connection terminals 26B and 26E by conductors embedded in the casing 12.
The conductive inserts 40 extend on the bases of two recesses 42 opening in the external surface of the base 24 of the casing.
The light source 18 comprises an SMC-type light-emitting diode 50 and two added pins 52 forming connection members.
A diode of the SMC (surface mounted component) type is intended to be welded directly to the tracks of a printed
circuit. For this purpose, it comprises flat conductive connection plates.
The connection pins are suitable for being fixed firmly, particularly by welding, to the conductive inserts 40. They extend through the conductive plates 30, through a central opening 54.
The pins 52 extend parallel to one another and are held between two partitions 60 formed integrally with the base 24 of the casing. These partitions project through the opening 54.
These partitions are arranged on either side of the conductive inserts 40, defining a channel 61 for receiving the pins 52 of the diode. Moreover, the upper ends of the partitions 60 generally extend in the region of the operating member 14, in the axial duct provided therein, and form a support surface for the light-emitting diode.
The facing surfaces of the partitions, indicated 62, converge towards one another, in the direction towards the base 24.
As shown in Figure 4, the diode 20 comprises a generally parallelepipedal, transparent body 70 having, along a lower surface 74, two coplanar connection plates 76. These plates are flush with the lower surface 74 of the body 70 or project slightly relative to that surface, extending in a common plane, parallel to the lower surface 74.
The connection pins 52 are constituted, in the embodiment of Figure 4, by blanked resilient plates comprising a main arm 80 which is extended at an end for connection to the diode
by a connection foot 82, forming a right angle with the main arm 80.
At its other end, the main arm 80 is extended by a tongue 83 which is bent into the shape of a hairpin along the surface of the main arm 80. A bend elbow 84 is defined between the tongue 83 and the main arm 80. At its free end, the tongue 83 has a tooth 85 diverging from the main arm 80 towards its free end.
As shown in Figure 4, the width of the connection pin is reduced in the vicinity of the bend elbow 84, the cross- section of the pin in this region, which is indicated 86, being suitable for entering a perforation 90 formed through the base of the casing and the connection inserts 40. In this region, the pin 52 is formed by the main arm 80 and the tongue 83.
In their regular portions, the main arms 80 of the pins have a width which decreases progressively from the foot 82 towards the portion 86 of reduced width.
The feet 82 are advantageously welded to the connection plates 76. This welding is performed, for example, by ultrasound welding.
After welding, the pins 52 generally extend parallel to one another and perpendicularly relative to the lower surface 74 of the diode, that is, perpendicularly relative to the surface containing the two conductive connection plates 76.
As shown in Figure 4, when the light source 18 is not mounted in the switching device, the tongues 83 are
separated from the main arms 80 of the members. The light source is assembled before being mounted in the casing 12.
After mounting and as shown in Figure 3, the pins 52 are held in their regular portions between the faces 62 of the internal partitions 60.
More precisely, the main arm 80 and the associated tongue 83 of each pin bear on the converging surfaces 62 of the partitions 60, the tongue 83 and the main arm 80 being pressed towards each other by resilient action on the bent region 84.
The tooth 85 is partially received in the thickness of a partition 60.
The connecting portion 86 extends through the perforation 90 so that the elbow 84 projects into the recess 42. In this position, the foot 82 bears on the upper end of a partition 60.
Finally, a weld, not shown for reasons of clarity, is formed between each insert 40 and the connecting portion 86 of each connection pin. This weld is formed, for example, by the supply of molten conductive material. The weld is housed entirely in the recess 42.
The use of a light source comprising an SMC-type light- emitting diode associated with added conductive pins provides a light source the head of which is at a greatly reduced height, measured along the extent of the connection members. The connection device itself is thus relatively compact axially.
In a variant, and as shown in Figure 6, the light source 18 is replaced by a light source 118 which differs from the light source 18 solely in that the pins, indicated 152, do not have bent tongues 83 but are reduced to a main arm, indicated 180, identical to the arm 80. The regular portion of the pins is thus constituted by a free end, the pins being formed by a single metal portion.