Multi-lead keyhole connector

[0001] This application claims priority to corresponding U.S. Provisional Application No. 60/759,447, filed on Jan. 17, 2006, which incorporates U.S. application Ser. No. 10/439,356, filed on May 16, 2003, U.S. application Ser. No. 11/077,934, filed on Mar. 11, 2005, U.S. application Ser. No. 11/105,230, filed on Apr. 12, 2005, U.S. application Ser. No. 11/105,231, filed on Apr. 12, 2005, U.S. application Ser. No. 11/105,232, filed on Apr. 12, 2005, U.S. application Ser. No. 09/998,733, filed on Nov. 30, 2001, and U.S. application Ser. No. 09/908,509, filed on Jul. 17, 2001, now U.S. Pat. No. 6,611,705, the disclosures and contents of which are expressly incorporated herein by reference.

[0002] The present invention relates to electrical connectors used to connect a single or multi-trace circuit to a separate electronic device.

[0003] In a multi-traced circuit, it is often desired that each electrical signal corresponding to each individual trace be kept electronically isolated from the other traces so as to maintain the integrity of each signal. However, oftentimes it is not practical that each trace be individually connected to a separate electronic device. Therefore, the need arises for an electrical connector that forms a single connection between a plurality of electrical traces and a separate electronic device without distorting the quality of the individual electrical signals. The need for such connectors has long been recognized in the medical field for connecting a plurality of electrocardiogram (ECG) leads to a separate device for capturing, storing, and analyzing the electrical signals sensed by a plurality of electrodes placed on a patient's chest. Previously, it was common to connect each ECG lead wire individually to a separate electronic device which often led to entanglement and confusion between the wires.

[0004] A serial port connector has been used to electrically connect a plurality of leads to a separate electronics device with only a single connection. A plurality of leads are combined to form a single information cable which is thereafter connected to a male portion of a serial connector comprised of a plurality of pins, each corresponding to a separate lead. The male portion is inserted into the pin recesses of a female counterpart that is located within the separate electronic device. Such a connection device is practically limited to electrical systems which utilize a plurality of lead wires that are physically moveable to one another and are not confined to a single plane. In a printed circuit or a circuit confined to a flat substrate, the electrical traces cannot easily be gathered to form a single information cable for input into a serial port connector. Furthermore, a printed circuit is limited to lying flat in one plane and therefore, a cable attached will have significant cable strain. Such a limitation is significant as there are a variety of applications in which a flat circuit is used to provide an electronic pathway between electrical components. For example, revolutionary ECG apparatuses have been disclosed which provide more comfort and mobility to the patient and a more stable configuration upon the patient's chest in the form of a flat, flexible chest patch. Integrated within the chest patch are several electrical traces originating from the electrode sensing means such that a conventional serial port connector is not a practical connection to a separate electronics device.

[0005] Typically with such flat circuits, the printed traces terminate along a common, flat trunk or terminal at one end of the circuit such that the traces are aligned adjacent to one another while still maintaining electrical isolation. The flat, printed circuit design is carried through to a connector plug that is attached to the end of the trunk. At the very end of the common trunk, the printed circuit traces ordinarily extend to corresponding contact strips or flat pins of a male connector portion. Where the contact strips lie, the insulating top surfaces of the flat substrate are ordinarily removed leaving the contact strips exposed along a support layer. These contact strips may also be printed conductors but may be formed of a different metal that is better suited for their insertion into a female connector socket located in a separate electrical device. Various mechanisms by which the male connector is inserted and held within the female socket have been disclosed. For example, the female socket may contain a plurality of spring contacts which mate with the contact strips upon insertion of the male connector. Clamps containing a series of teeth are biased into contact with the springs such that the springs are held against the inserted connector. Furthermore, the female socket may contain finger hooks which hook onto apertures that may be formed on the male connector thereby securing the male connector within the female socket. However, due to the fact that these insertion-type connectors require multi-part internal mechanisms for securing the connector at the female socket, they are complex to manufacture, hard to clean, and it is difficult to maintain a waterproof connection.

[0006] It is an object of this invention to provide a simpler mechanism for connection between a flexible, flat circuit that contains conductive electrical traces to a separate electronics device. The conductive traces terminate on the bottom of a female connector plug that contains one or more keyhole-shaped slots where each trace corresponds to one slot. Insert-molded pins corresponding to each of the keyhole-shaped slots are located on the surface of the body of a separate electronics device. Proximate to the pins are electrical contacts in the body's surface. The plug is placed over the pins such that the pins are inserted up through the wider portion of the slots and in a push or pull action, the pins are slid into the narrower portion of the slot such that the pins are locked into place. The conductive traces are then secured into contact with the electrical contacts of the separate electronics device. Therefore, all of the connecting parts are made by simple construction and are found on easily accessible, exterior surfaces of the plug and body rather than on an interior surface that is difficult to reach and hard to clean.

[0007] It is an object of this invention to provide a completely waterproof mechanism for connection between a flexible, flat circuit that contains conductive electrical traces to a separate electronics device. In the assembly described above, a single rubber gasket is placed on the surface of the body where the body contacts the plug thereby creating a completely waterproof fit between the plug and the body when in connection with one another. Due to the fact that the plug is connected to the body simply by sliding the plug in an overlapping configuration about the body surface such that the electrical contacting parts are sandwiched between the two surfaces, waterproofing is made easy by simply applying a gasket between the two surfaces.

[0017] The present invention is a keyhole-shaped electrical connector that is used to connect a single or multi-trace, rigid or flexible circuit to a body of a separate electronics device comprised of one or more fixed pins which serve to mechanically secure the connection between the trace(s) and electrical contacts on the body. In addition to the mechanical use, preferably the pins also maintain electrical continuity between the circuit and the body. The system is designed to be waterproof in such a way that the electrical connection is maintained even while immersed in fluid after the system has been assembled and can be easily cleaned. The arrangement is particularly suitable for securing multiple electrical traces within a flexible membrane circuit of an ECG chest assembly to the body of an electronics unit located on a patient for wireless transmission of ECG data. Electrically conductive tracings may be applied as silver epoxy ink or other conductive means known in the art to a non conductive, flexible substrate such as Mylar.

[0018] Referring to FIGS. 1 and 2, body 4 of the male portion of the connector may contain one or more pins 2 having a conductive element or being made from a conductive material including a conductor or a metallic conductive material in a recessed portion 5 of its surface. The pins have a wide mushroom-head shaped cap and a base of narrower diameter. The pin cap may be further covered by an insulation cap 3 that is preferably composed of a non conductive material such as a plastic or an elastomer. In the surface of the body, proximate to the pins, are electrical contacts 6. The male connector is preferably incorporated into the body of a separate patient electronics unit but may be incorporated onto a conductive cable extending from such patient electronics unit.

[0019] The connector is comprised of a female plug portion 7 with top surface 8 and bottom surface 9. Preferably, the plug is comprised of a nonconducting plastic. The top surface 8 may be in the form of a dome-shaped cover 12 that is attached to the bottom surface [as shown in FIG. 1] such that the unit is reasonably waterproof when assembled. As shown as exposed in FIGS. 1, 4A and 4B, bottom surface 9 of the female plug portion contains one or more keyhole-shaped slots 20 which correspond to pins 2 located on the body of the separate electronics device. As shown in FIGS. 3A and 3B, the keyhole-shaped slot is comprised of a portion of wide diameter 13 that opens into a portion of narrower diameter 14. Portion 13 is depicted in the shape of a circle for illustrative purposes only and in no way limits the shape of portion 13 to a circle. Any shape can be used as long as one portion is large enough to receive the mating pin and another portion is small enough to retain the pin when engaged in the slot. Referring to FIGS. 1 and 5, flexible circuit 1 terminates on the bottom surface of the plug such that each electronic trace 11 within flexible circuit 1 corresponds to one keyhole-shaped slot 10. As shown in FIG. 7B, a double-sided foam adhesive 25 may be applied between the bottom surface 9 of plug 7 and flexible circuit 1 in order to retain the circuit on the bottom surface of the plug. Additionally, a single-sided foam adhesive layer 19 may be applied to the bottom surface of the flexible circuit as shown in FIG. 7A.

[0020] In order to engage the electrical traces 11 on female plug 7 in electrical contact with contacts 6 of body 4, portion 13 of slots 10 are first placed over pins 2 such that the pins come through portion 13 as shown in FIG. 4A. Thereafter, in either a simple push or pull sliding action, the pins are forced through the narrower portion 14 such that the pins are restrictively secured in place at the end of slots 20 in a single orientation as shown in FIG. 4B. Referring to FIGS. 1, 2 and 3A, a cone structure 17 may be applied to the narrow end 14 of slot 20 in order to provide better gripping force and a larger surface area for electrical connection between plug 7 and pins 2. As shown in FIG. 3B, electrical traces 11 of flexible circuit 1 are deflected along the undersurface of cone 17 thereby creating a larger surface area for electrical connection between traces 11 and pins 2. As also shown in FIGS. 1 and 3A, ramp structure 16 is placed along the narrower portion 14 such that pin 2 glides easily into electrical contact with cone structure 17. The cone and ramp structures may be composed of any material with suitable mechanical and electrical properties with cardboard or plastic being most preferred.

[0021] Alternatively, pins 2 may also serve as a point of electrical contact between electrical traces 11 on plug 7 and body 4.

[0022] As shown in FIGS. 1 and 2, a rubber or other type of gasket material 15 may be applied to the recessed surface 5 on body 4 such that the gasket surrounds pins 2 of the male portion of the connector in order to ensure a watertight seal between plug 7 and body 4 when brought into contact.

[0023] In an alternative embodiment as shown in FIGS. 6A and 6B, dome cover 12 does not form the top surface of plug 7 but rather, is composed of rubber and is attached to the body 4 using a living hinge 18. After the plug is secured to the pins, the dome is closed at the hinge and press fit into the recessed portion 5 of the body thereby covering or encapsulating the plug so as to provide a watertight seal.