Patent Application
20060258202
This invention relates to an electrical switch and lamp assembly which includes at least one insulation displacement connector for making electrical contact with insulated wires attached to the switch.
There are places where a rather thin switch and lamp assembly is desirable. An example is with a vanity mirror mounted in a sun visor on an automobile. A lamp to illuminate the user is common, and these may be turned on and off by a switch actuated by movement of the vanity mirror cover. It is desirable that such mechanisms be kept as thin as possible so that the total thickness of the sun visor is minimized.
It is found that using an insulation displacement connector for making electrical connections to the lamp and switch assembly is quite desirable. Insulation displacement connectors (commonly referred to as IDC's) have been known at least as early as 1961. As shown in U.S. Pat. No. 3,012,219. These are widely used for making telephone connections, for example, Such connections have been used on electrical switches as well. Better ways of implementing and making connections to a switch or the like with an IDC are desirable to make the assembly process simpler and more efficient.
There is therefore provided in practice of this invention an insulation displacement connector adjacent a wire-receiving groove in an insulating base. An insulation displacement connector has a fixed end secured on the base and a movable end with an insulation displacement slot on an end of the connector transverse to the length of the groove. The movable end is cantilevered from the fixed end. The movable end of the connector is retained in a position with the slot moved toward the bottom of the groove to make electrical connection with a wire in the groove.
A lamp and switch with an insulation displacement connector has a pair of wire receiving grooves in an insulating base and a pair of upstanding walls straddling each of the grooves. A pair of metal connector members each have a fixed end secured to the base. A movable end on such a connector includes an insulation displacement slot extending in a director transverse to the groove in the base. A switch contact extends from a fixed end on one of the connectors. The lamp is mounted on the base with a wire electrically connected to one of the connector members. The switch contact member is elastically deflectable between an open position away from the switch contact extension, and a closed position in engagement with it. The switch contacts are in approximately the same “plane” as the base. Each of the metal connector members has a pair of opposed ears on the movable end with the distance between the ends of the ears being greater than the distance between the upstanding walls. Thus, when the movable end is pressed against a wire in the groove, the wire is straddled by the slot and the ears plastically engage the walls to inhibit retraction of the slot away from the electrical connection.
These and other features and advantages of the invention will be appreciated as the same becomes better understood by reference to the following description when considered in connection with the accompanying drawings wherein:
A switch and two serially connected incandescent lamps 10 are mounted on an elongated insulating base 11 which is typically made of injection molded plastic. The base includes a number of reinforcing ribs, mounting holes and the like, which are illustrated but need not be described for an understanding of the invention. Such mounting arrangements may be different when such an assembly is used in a context different from the one for which the illustrated assembly is best suited.
In this embodiment, the lamps are connected in series by an insulated wire 12. Another insulated wire 13 from one of the lamps passes between a pair of support posts 14 and is connected to a metal pad 16. (For convenience of illustration, the end of the wire 13 is shown without the insulation stripped from the end. Also, the conventional crimp-type fastener 17 on the pad is shown open to receive the stripped wire before crimping. The crimps are closed in the process of manufacturing and before shipping the assembly to the customer.) The second wire from another lamp is similarly mounted via a crimped connection to one of a pair of insulation displacement connectors 19 (IDC's).
The two IDC's are generally similar and only one needs to be described. In fact, in the enlarged fragmentary view of
The other end 24 of the IDC is movable toward and away from the base since it is connected to the fixed end by a narrowed center section 26, which is easily flexed. Thus, the IDC is essentially in the form of a cantilever fixed at only one end. The center section is preferably narrowed by a central opening to make that portion of the IDC easier to bend.
The movable end of the IDC is bent in an L-shape to have a portion extending transverse to a rounded wire-receiving groove 27 in the base. (The groove could be V-shaped, if desired.) This bent portion has a pair of tines defining a central slot 28 therebetween. For ease of description, it is assumed that the bottom view of
To make an electrical connection to an external wire, an insulated wire such as the wire 29 illustrated in
The downward motion of L-shaped end of the cantilever arm is guided by the slot 31 in the adjacent plastic base for minimized tendency toward twisting and to assure travel in a direction normal to the principal length of the IDC, i.e., in a direction parallel to the slot in the free end. The central weakened section of the cantilever arm permits the L-shaped free end of the arm to move “vertically” downwardly by buckling or bending the arm upwardly in its mid-portion. Otherwise the L-shaped end would move in an arc as the cantilever arm bends. The mid-portion of the sheet is more readily bendable than the principal balance of the sheet because of the longitudinal slot.
The length of the opening 31 in the base which receives the movable end of the IDC is only a little more than the width of the sheet making the tines on the end of the IDC. The tines extend a little ways into the opening, thereby providing guidance for the end of the IDC as it is moved downwardly to a wire-engaging position. This contributes to making the IDC insensitive to off-center application of closing forces.
The movable end of the IDC has four ears 32 in pairs on opposite edges of the movable end. It will be noticed that the ears are bent upwardly from the movable end so that they are rounded or angled diagonally on the bottom face and have a relatively sharp non-rounded edge aligned upwardly. (In fact, it is helpful that a slight burr is often present on the outer non-rounded edge of the ears due to stamping the sheet metal part.) When the IDC is pressed down onto the wire, the ears pass between a pair of upstanding walls 33 on the base. The distance between the edges of the ears is slightly larger than the distance between the walls, so that as the metal moves down, it may plastically deform the walls. However, the non-rounded edges of the ears would dig into the plastic if the movable end were to move upwardly, and they, therefore, act as a pawl with the walls acting as a ratchet to hold the movable end down against the wire.
To make electrical connections to the lamp and switch assembly one simply inserts an insulated wire into the groove underlying the movable end of the IDC. Ordinarily, the assembler inserts a pair of wires into the respective grooves until they engage plastic body at the far end of the grooves. The movable end of the IDC is then pressed downwardly toward the base and the tines on each side of the slot in the IDC displace insulation from the wire and make electrical contact with the wire. Again, the assembler ordinarily presses both IDC's down simultaneously. The top of the plastic body engaging the underside of the IDC arm forms a stop defining the maximum bending of the IDC arm. As the movable end is pressed downwardly toward the base the ears on each edge scrape along the plastic of the opposing walls and may displace some of the plastic. Because of this, when the force pressing the movable end into electrical contact with the wire is released, the non-rounded edges of the ears dig into the plastic of the walls and hold the tines on each edge of the slot in continued engagement with the wire. Thus, the ears and walls act as a ratchet to permit downward movement of the movable end and preventing upward movement.
As best seen in
The arrangement of switch contacts operable by pressing laterally toward the base contributes to the “thinness” of the assembly. These switch contacts lie in approximately the same “plane” as the plastic base of the assembly. The assembly is basically flat, but not planar since it has varying thickness in different areas. For example, the total thickness when the IDC's are down and engaged with wires is only slightly more than 0.3 inch. Thus, by lying in the same “plane”, it is meant that the switch contacts do not protrude significantly above or below the plastic base. (In the illustrated embodiment, the switch contacts actually extend a small distance below the largest flat surface of the bottom of the base and only some small areas of the base extend as far as the maximum extension of the switch contacts.) Similarly, the IDC's are approximately in the same “plane” as the base when engaged with a wire. Before engagement, the movable ends of the IDC's are about ⅜ inch above the bottom of the base, but when pressed down, they are within the 0.3 inch thickness.
The external electrical connections can be made to the assembly either before or after it is mounted in the place where it is to be used. The external connections can be made before mounting since when an IDC is used with the appropriate size of wire the IDC securely engages the wire and successfully resists normal handling.
No special tools are needed for engaging the IDC's with the respective external wires. Almost anything the right size can be used to press the movable end into engagement with the external wire. Simple finger pressure may be used, although the cantilever in an exemplary embodiment is stiff enough that finger pressure is not suitable for use on a production line. A small “U” shaped manual or pneumatic tool may be used, if desired, to press the IDC's into engagement with the respective wires simultaneously. Simultaneous engagement is desirable to avoid inadvertently pressing one of the IDC's downwardly before a wire is in place.
The IDC's employed in this assembly differ significantly from anything previously known. The cantilever IDC is flexed in the center section 26 and then latched in place by the ears engaging the walls. It may be noted that the walls engaging the ears also serve as a guide to assure that the slot remains centered over the wire. The wire is centered because it lies in a round bottom (or V-shaped) groove and also because there is a V-shaped throat at the open end of the slot.
Referring back to
There is one feature of interest in the area of the base illustrated in
Although one embodiment of the IDC, a lamp and switch assembly has been described and illustrated herein it will be apparent that there are variations that can be made embodying the principles of this invention. For example, in this embodiment the movable end of the IDC is latched into engagement with the wire by an opposing pair of ears. A single ear or pair of ears extending from the movable end 90° from the location illustrated, may engage a surface on the base which is also 90° from the opposing faces of the walls on the base. In other words, the ear or ears would stick out in the same direction as the length of the IDC illustrated. Other ways of narrowing the center portion of the cantilever for ease of flexing will be apparent. Electrical connections between the IDC's and switch contacts may differ. Clearly, details of the base will differ for different applications. An IDC as described may be used in quite a different context than the assembly described and illustrated herein. Thus, within the scope of the following claims, the invention may be practiced differently from the embodiment illustrated and described in detail.
This application claims the priority benefit of U.S. application Ser. No. 10/913,669, filed Aug. 6, 2004, which claims the priority benefit of U.S. Provisional Application Ser. No. 60/523,449, filed Nov. 19, 2003.
| Number | Date | Country | |
|---|---|---|---|
| 60523449 | Nov 2003 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 10913669 | Aug 2004 | US |
| Child | 11491425 | Jul 2006 | US |
