BACKGROUND OF THE INVENTION
The present invention relates to a switching device of the type comprising a casing forming a cavity, a switching mechanism in the casing and an operating member for operating the switching mechanism. A light source carried by the casing is connected to energizing conductors. The light source comprises a LED (light emitting diode) element and at least two connection members extending at least partially through the casing to the energizing conductors. The light source illuminates a control button of the operating member.
In order to be visible from the operating region at which the control button is pushed, the light source must be positioned outside the switching mechanism. The LED is commonly constructed with a transparent head that contains a light-emitting semiconductor element. The LED element is connected to a pair of conductors that are embedded in the transparent head and that have free ends forming flat conductive connection areas on a side of the transparent head. Such flat connection areas are suitable for surface mounting on a circuit board by direct soldering to traces on the circuit board. Such LED's are widely available at moderate cost.
In practice, the internal region of the casing of the switching device is occupied by the switching mechanism. In a switching device where the control button is depressed, or pushed down, the presence of the LED can result in a tall switching device.
A major object of the invention is to provide a low cost switching device with a light source that is compact in height.
SUMMARY OF THE INVENTION
The present invention provides a compact switching device with a SMC-type (surface mounted component type) light-emitting diode (LED) element, of the type that has a body and at least two flat, conductive and coplanar connection plates on the body. The switching device includes a pair of contacts, or connection members that each comprises a base portion that is conductively joined (e.g. by solder or an ultrasonic weld) to one of the connection plates of the LED element. Each connection member also has a pin portion that projects deeply into the casing and below the switching mechanism where it connects to an energizing conductor that supplies electricity. The switching device can include one or a plurality of the following characteristics:
each base portion is ultrasonically welded to the associated connection plate;
each pin portion comprises an arm and comprises a foot extending primarily parallel to each other at a bend of almost 180°, and engaged with one of the energizing conductors;
the casing comprises at least two partition walls which project up into a cavity of the casing and which form channel portions between them into which the pin portions of the connection members are inserted and where they are held;
the foot of each pin portion has a locking tooth that engages one of the casing partitions in order to fix the position of the light source;
the light-emitting diode bears against a top end of at least one partition wall;
each energizing conductor has a perforation, or hole, through which the corresponding pin portion projects and where the pin portion is conductively joined to the energizing conductor.
Other characteristics and advantages of the invention will become apparent from reading the detailed description which follows for the understanding of which reference will be made to the appended drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an exploded isometric view of a switching device according to the invention.
FIGS. 2 and 3 are sectional views taken on the planes P2-P2 and P3-P3, respectively, of the switching device illustrated in FIGS. 2 and 3.
FIG. 4 is an enlarged isometric view of a first embodiment of a light source for the switching device of FIGS. 1 to 3.
FIG. 5 is a bottom isometric view of the assembled switching device of FIGS. 1-3.
FIG. 6 is an isometric view, similar to that of FIG. 4, of a variant of the light source according to the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 shows a switching device 10 that includes a casing 12, an operating member 14 movable relative to the casing 12, and a switching mechanism 16 housed in the casing 12. The switching device also includes 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 indicated at 22 in FIG. 2, is fitted on the operating member 14, over the light source 18, to improve visual appearance and facilitate operating when the switching device is installed in an electronic apparatus, particularly a portable telephone. In the drawings, arrows U and D designate upward and downward directions, and it is assumed that the button 22 is pushed downward to operate the switch.
The casing 12 is generally of parallelepipedal shape and formed of insulating plastic material. The casing forms a cavity 22 of generally cylindrical shape, closed at one end by a base 24. Six connection terminals 26A, 26B, 26C, 26D, 26E and 26F (FIG. 5) project laterally from opposite sides of the base 24, for mounting on a circuit board. Four of the terminals 26A, 26C, 26D, 26F are connected to a conductor 28 (FIG. 2) lying in the housing 22 in the vicinity of the base 24.
The switching mechanism 16 (FIG. 1) which lies the cavity 22, comprises two superposed metal conductor switching plates 30 with central holes 31 that closely receive partitions 60 of the casing. The switching plates are identical and formed of sheet metal, and generally have convex surfaces with one convex surface lying on the base 24. The switching plates have four radially-projecting arms 32 for contacting conductors 28 (FIG. 2) to close circuits as is known in the prior art. At rest, the arms normally extend away from the conductors 28. The arms have to be resiliently deflected to be brought into contact with the conductors 28, which is accomplished by depressing the operating member 14.
The operating member 14 generally has an annular shape defining an axial duct 31 (FIG. 3) for receiving the light source 18. The operating member 14 can be displaced by sliding it along the axis 33 (FIG. 2) of the cavity 22 to downwardly depress or release the arms of the conductor plates. In a conduction position in which the arms 32 of the plates 30 are in contact with the conductors 28, terminals 26A, 26C are in communication with the terminals 26D, 26F, respectively. In a rest position as illustrated in FIGS. 2 and 3, the arms of the plates 30 are separated from the conductors 28.
The light source 18 is electrically connected to two current-carrying energizing conductors 40 in the form of inserts at 40. The inserts are fixed firmly in the casing and connected to the connection terminals 26B and 26E by conductors embedded in the casing. The conductive inserts 40 extend on the bases under two recesses 42 that open downward to lower surface of the base 24 of the casing.
The light source 18 comprises an SMC-type light-emitting diode element 50 (FIG. 4) and two added contacts, or connection members 52. The diode element 50 illustrated is of the SMC (surface mounted component) type which is intended to be electrically connected (e.g. by solder) directly to the tracks of a printed circuit board. For this purpose, the diode device comprises flat conductive connection plates 76. The connection members 52 are suitable for being fixed firmly, in electrical connection joints, to the conductive inserts, or energizing conductors 40 (FIG. 3) that supply electricity to the LED. The inserts 40 extend through a central opening 54 (FIG. 2) in the conductive plates 30.
The casing partitions 60 (FIG. 3) form channel portions 61 and lie above the energizing conductor conductive inserts 40. The inserts have holes under the channel portions for receiving the connection members 52 of the light source. The upper ends of the partitions 60 lie within the duct 31 of the operating member 14, and form a support surface for the light source. The facing surfaces 62 of the partitions converge downwardly D towards one another. As shown in FIG. 4, the light source 18 includes a generally parallelepipedal, transparent body 70 having a lower surface 74 and two coplanar surface mount connection plates 76 on the lower surface. The lower surfaces of the surface mount plates are flush with the lower surface 74 of the body 70 or project only slightly below the lower surface. The surface mount plates 76 (which are shown as parts of right angle bent sheets) extend in a common plane that is parallel to the lower surface 74.
As shown in FIG. 4, the connection members 52 are formed of blanked metal plates. Each connection member 52 has a base portion 82 that is electrically joined (e.g. by soldering, brazing, ultrasonic welding, etc.) to a surface of one of the surface mount plates 76. The electrical-mechanical joints are not shown. Each connection member also has a pin portion 86 connected by a 90° elbow or bend 88 to the base portion. Each pin portion 86 has an arm 80 and has a foot 83 joined to the arm at a bend 84 of more than 135°, and which approaches 180°. FIG. 3 shows that when the arm is installed in a channel portion 61 the arm 80 and foot 83 extend largely parallel. At its free end, which is furthest from the bend 84, the foot 83 forms a tooth 85 diverging away from the arm 80.
The width of the connection pin is reduced in a region 89 (FIG. 4) in the vicinity of the bend 84. The narrow region 89 is suitable for projecting into a perforation 90 (FIG. 2) formed through the base of the casing and through a hole in an energizing conductor 40. The pin portions 86 are preferably joined, as by solder, to the conductors 40 at the holes therein. To mount the pin portions 86 of the connection members, the pin portions are pressed down into the channel portions 61 (FIG. 3) of the casing. The arm 80 and foot 82 of each connection member are resiliently deflected closer together and resiliently bear against the downwardly converging surfaces 62 of the partition portions 60. The tooth 85 adds to resilience and holding. When the pin portions are fully inserted the base portions 82 bear against the upper end of the partitions 60. The electrical joint between the pin portion and energizing conductor lies entirely in the recess 42.
The use of a light source comprising an SMC-type light-emitting diode and added connection members provides a light source of reduced height.
FIG. 6, shows a variant 118 of a light source which differs from the light source of FIGS. 1-5 in that the connector members 152 have pin portions 180 that do not have almost 180° bends. The pin portions have tapered parts 160 that fit in tapered channel portions with the bottom of the pin passing through a hole in an energizing conductor that lies under the channel and soldered thereto to the energizing conductor.
Although terms such as “up” and “down” have been used to describe the switch device as it is illustrated, the switch device can be used in any orientation.
Although particular embodiments of the invention have been described and illustrated herein, it is recognized that modifications and variations may readily occur to those skilled in the art, and consequently, it is intended that the claims be interpreted to cover such modifications and equivalents.
Patent Application
20050263381
