Switch having a complementary diode unit

A diode unit (9) including at least one diode (13) and a pair of terminals (15) is mounted on a switch body (2) having an actuate-able key (6) and at least two terminal points (4). The diode unit (9) is positioned on the exposed end of the key (6) such that surface parts of the diode unit (9) is brought into engagement with corresponding surface parts of the switch body (2) so as to prevent the diode unit (9) from movement in relation to the switch body (2) in a predefined plane. The diode unit terminals (15) extend in a direction transverse to said plane, and the diode unit terminals (15) are connected to the terminal points (4) of the switch body (2) so as to prevent movement of the diode unit (9) in relation to the switch body (2) transversely to said predefined plane.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit and priority to and is a U.S. National Phase of International Application No. PCT/DK2006/000063, filed on Feb. 7, 2006, designating the United States of America and published in the English language, which claims priority under 35 U.S.C. §119 to Danish Patent Application Number PA 2005 00227, filed on Feb. 15, 2005. The disclosures of the above-referenced applications are hereby expressly incorporated by reference in their entireties.

The present invention relates to a switch and particularly to a switch comprising a complementary diode unit mounted thereon. The switch may e.g. be of the type disclosed in U.S. Pat. No. 5,199,557.

BACKGROUND OF THE INVENTION

Electronic switches are available in a range of versions depending on the actual application, the manufacturing methods used, etc. U.S. Pat. No. 5,199,557 discloses different designs of switches comprising one or more diodes mounted thereon. The switch is intended to be mounted e.g. in a keyboard panel by the so-called the Surface Mounting Technique (SMT). However, the diodes cannot withstand this process wherein the tin may be heated for e.g. 240° C. for approximately 60 seconds, and they are therefore mounted afterwards. The diode is mounted in a socket received in the inner space of a push button extender, and the diode terminals extend through slits of the push button extender and further through apertures of the housing component of the switch.

SUMMARY OF THE INVENTION

It is an objective of the present invention to provide a switch that can be manufactured in an automatic process without the need for later mounting of the one or more diodes, and to provide a method of making such switch.

An aspect of the present invention relates to a method of mounting a diode unit including at least one diode and a pair of terminals on a switch having an actuate-able key and a switch body with at least two terminal points, said method comprising positioning the diode unit on the exposed end of the key such that surface parts of the diode unit are brought into engagement with corresponding surface parts of the switch body so as to prevent the diode unit from movement in relation to the switch body in a predefined plane, extending the diode unit terminals in a direction transverse to said plane, and connecting the diode unit terminals to the terminal points of the switch body so as to prevent movement of the diode unit in relation to the switch body transversely to said predefined plane.

The method may ensure a secure fastening of the diode and thereby an easy-to-handle switch which is ready for mounting e.g. in a keyboard panel without the need for later mounting of the diode(s). If the switch is mounted with SMT-technique or another mounting technique involving heating, it is necessary to use diodes that are resistant to the temperatures involved.

In a presently preferred embodiment of the invention, the diode unit is arranged within a recess formed in the exposed end of the key and defined by a surrounding peripheral wall, the diode unit terminals extending through openings or slits formed in said peripheral wall. The recess may have any shape which allows arrangement of the actual diode unit according to the invention. It may e.g. have the same shape as the outer geometry of the diode unit to be placed therein. The cross section of the recess may be substantially circular, or it may have any other shape such as substantially rectangular.

The diode(s) may be mounted in a socket having projections including said diode unit terminals, said projections being arranged so as to extend though said openings or slits formed in the peripheral wall of the key. The shape of the socket may be substantially circular, or it may have any other shape such as substantially rectangular. The clearance between the diode unit and the key is preferably so as to allow actuation of the key without influencing the diode unit.

The connecting of the diode unit terminals to the terminal points of the switch body preferably comprises the steps of mechanically interconnecting the diode unit terminals and the terminal points of the switch, and soldering the connection between the diode unit terminals and the terminal points of the switch. The mechanical interconnection ensures that the diode unit is kept in the right position even if the mounting of the switch includes heating. The soldering may enhance the electrical connection between the diode unit terminals and the terminal points of the switch body, and it may furthermore improve the securing of the diode unit during handling of the switch.

Each terminal point of the switch body preferably comprises a pair of slightly mutually spaced terminal pins, said connecting of the diode unit terminals comprising positioning each diode unit terminal between a respective pair of said terminal pins, and pressing the pins together around the diode unit terminals. However, each terminal point may also comprise only one terminal pin or three or more terminal pins. The step of mechanically interconnecting the diode unit terminals and the terminal points of the switch body may also include twisting or bending the terminal pins.

Another aspect of the invention relates to a switch comprising a switch body having at least two terminal points, and an actuate-able key mounted on said switch body and having a diode unit including at least one diode and a pair of terminals mounted on the exposed end of the key, surface parts of the diode unit engaging with corresponding surface parts of the switch body so as to prevent the diode unit from movement in relation to the switch body in a predefined plane, the diode unit terminals extending in a direction transverse to said plane and being connected to the terminal points of the switch body.

The diode unit is preferably arranged within a recess formed in the exposed end of the key and defined by a surrounding peripheral wall, the diode unit terminals extending through openings or slits formed in said peripheral wall. The key may have any shape, such as having a substantially circular or rectangular cross section. The peripheral wall may have a cylindrical outer surface, i.e. the key has a substantially constant cross section along its height, or the cross section may vary.

The diode(s) is/are preferably mounted In a socket having projections including said diode unit terminals, said projections being arranged so as to extend though said openings or slits formed in the peripheral wall of the key. The diode(s) is/are preferably mounted in a cavity formed in the socket. They may be mounted e.g. by gluing or soldering.

In a presently preferred embodiment of the invention each terminal point of the switch body comprises a pair of slightly mutually spaced terminal pins, each terminal of the diode unit being positioned and pinched between a respective pair of said terminal pins.

The engaging surface parts of the diode unit and the switch body, respectively, may preferably comprise substantially complementary surface parts.

The switch body may further comprises at least four terminal components extending outwards from one or more outer side wall(s) of the switch body, at least two of the terminals each being electrically connected to a respective terminal point. The terminal components may be placed on one, two or more sides of the switch body. They are preferably adapted to be mounted on a plane surface

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 1illustrates a preferred embodiment of a switch1according to the invention in which the switch body2has four terminal components3, three of which are visible in the figure. The switch body2further comprises two terminal points4(only one of them Is visible In the figure) positioned at opposite sides of the switch body2. In the preferred embodiment shown, each terminal point4comprises a pair of slightly mutually spaced terminal pins5. The switch1further comprises an actuate-able key6which when actuated moves along its axis of symmetry. The key6has a recess7formed in the exposed end of the key which recess7is defined by a surrounding peripheral wall8.

The diode unit9has a socket10with a cavity11comprising contacts12for the diode(s)13and projections14each including one of the diode unit terminals15. The projections14are arranged so as to extend though slits16formed in the peripheral wall8of the key6. At least one diode13is/are mounted in the cavity11of the socket10in electrical connection with the contacts12. The switch1according to the present invention is preferably adapted to be used with light-emitting SMD-diodes, but it is possible to use any type of diode suitable for the actual application and mountable in a diode unit according to the invention.

FIGS. 2aand2bshow a switch with one diode13, andFIG. 3shows an embodiment with two diodes13. It may also be possible to use three or more diodes for the switch provided that there is enough space in the cavity11of the socket10.FIGS. 2 and 3show two different shapes of the cavity11for mounting of the diode(s)13. The sizes of the cavities11shown may be adjusted to the size(s) of the diode(s)13. The shape of the cavity11may therefore be of any shape adapted to receive a desired type and size of diode13. However, it may also be possible to use diode units9having a socket10with a cavity11adapted to receive a varying number of diodes for the same cavity geometry and size.FIG. 2bis a top plane view of the switch inFIG. 2awhich illustrates a preferred embodiment of the invention. The projections of the diode unit14may also extend from other positions of the socket10, such as symmetrically from the socket10. For such embodiments it is necessary to use a complementary geometry of the switch body.FIGS. 2 and 3illustrate preferred embodiments of the invention in which the geometry of the diode unit makes it possible to mount the diode unit in any of the two possible directions. The electrical circuit of the whole switch is then determined by the polarisation of the diode(s)13. However, it may also be possible to have diode units9that have to be mounted in one predetermined way. The right mounting must then be ensured e.g. by indications on the switch or by using a geometry that restricts the possible ways of mounting.

FIG. 4illustrates a preferred way of making the electrical connections in a switch.FIG. 4ais a top plane view of a switch, andFIGS. 4band4care diagrams of the electrical connections of switches having one and two diodes, respectively. The signs17shown on the switch body inFIG. 4aare examples of possible markings aimed at guiding the mounting of the switch e.g. in a keyboard panel. The numbers shown correspond to the numbers of the terminal components shown inFIGS. 4band4c.The contact members18in the middle ofFIGS. 4band4cindicate actuating the key. As illustrated InFIG. 4a, terminal component2is electrically connected to one of the terminal point (marked as −), and terminal component3is electrically connected to the other terminal point (marked as +). However, other possible connections between the terminal components and the terminal points will also be possible within the scope of the invention. These connections may e.g. be established by producing all the terminals used for a switch body from one piece of electrically conductive material.

FIG. 5is an exploded view of a preferred embodiment of the invention. The switch body comprises a housing19preferably made from an insulating material cast around a terminal unit (not shown) comprising terminal components3, each extending outwards from an outer side wall20of the housing19, and terminal points4. The terminal unit further comprises electric contact members (not shown) for electrical contact to a switching element21, such as a contact dome. The housing19of the switch body has a recess22for receiving the switching element21and providing a packing surface for a rubber component23, such as a silicone dome. These two elements21,23are placed in guided contact with the housing19. The switchable element21is switchable between a first state in which it is out of electrically conductive contact with at least one of the electric contact members (not shown), and a second state in which the switching element establishes electrically conductive contact between the electrical contact members. An actuate-able key6is placed on top of the silicone dome23. The key6has slits16that enable actuation of the key6also when the diode unit9is mounted with the projections14extending through the slits16. The key6has guides24for correct positioning of a cover25of the switch body. The cover25is fastened to the housing19e.g. by ultrasound welding or gluing. The figure illustrates a possible design of complementary surfaces of the switch body and the diode unit. However, any design that prevents the diode unit9from movement in a predefined plane in relation to the switch body is covered by the scope of the invention.

In a switch according to the present invention each terminal point4of the switch body2is electrically connected to one of the terminal components3of the switch body2. Since the terminal points4are connected to the diode unit terminals15during mounting, the electric connection to the diode(s)13is established when the four terminal components3of the switch body2are mounted to e.g. a key board panel. Hereby the need for establishment of additional electrical connections to the diode(s) is eliminated.

The switch as described above can be used in accordance with Surface Mounting Technique (SMT). However, other manufacturing methods may also be applied within the scope of the invention.

In a preferred embodiment of the invention, the diode socket10and the switch housing19are produced by casting an insulating material around the terminals. However, it may also be possible to cast the insulating components separately and mount the terminal components thereto afterwards, e.g. by gluing.