ELECTRICAL CONNECTOR

Abstract: The invention relates to electrical connectors and in particular to a board mountable socket, a plug for connection to such a socket and a method of attaching a socket to a board. The socket of the invention comprises two main parts, a socket base (1) and a socket head (2). The socket head comprises locking means (34, 35) for locking the socket head (2) to the board, the arrangement being that, in use, the socket base (1) is secured to the board by placing the socket base (1) between the socket head (2) and the board and locking the socket head (2) to the board.

Description: ELECTRICAL CONNECTOR The present invention relates to electrical connectors, particularly although not exclusively to an electrical connector for connection to a printed circuit board. According to one aspect of the present invention there is provided a board mountable electrical socket comprising: a socket base; and a socket head, wherein the socket head comprises locking means for locking the socket head to the board, the arrangement being that in use, the socket base is secured to the board by placing the socket base between the socket head and the board, and locking the socket head to the board. Suitably, the socket is adapted for fitment to a printed circuit board. Preferably, the socket base comprises means for seating the base in an aperture in the board. Preferably said seating means comprises a rim extending around an upper end of the base. Preferably, the socket base is adapted for receiving a first plurality of electrical connectors. Preferably, said base is provided with a plurality of passages extending through the base, each said passage arranged for receiving a said electrical connector. Preferably a said electrical connector comprises a connector pin, preferably a female connector pin. Said connector pin may comprise a crimp connector. Preferably, a said passage is arranged such that a said electrical connector pin may be inserted into the passage from a lower end of said passage, and pushed through said passage, so as to partially protrude from an upper end of said passage, a portion of said electrical connector pin remaining in said passage. Preferably, said passage is surrounded or partially surrounded by a pin seating portion. The pin seating portion is preferably arranged around a periphery of said passage such that said pin seating portion may expand when a said electrical connector pin passes through said passage in a first direction, and may contract thereafter, thereby preventing passage of said electrical connector pin in a second direction, opposite to said first direction. Preferably, a said pin seating portion comprises a substantially tubular portion surrounding said passage. Preferably said socket head comprises a substantially tubular member having a lower end arranged to engage said socket base portion, said lower end being provided with said locking means for locking the lower end of said socket head to a board. Preferably, in use, where the socket is to be fitted to a board, for example a printed circuit board, an aperture is formed in the printed circuit board the aperture having a periphery of a shape which closely fits the base, such that the base may be inserted through the aperture from a position at an upper side of the board, the base being prevented from passing completely through the aperture by the seating rim at the upper end of the base, the seating rim arranged to locate around the periphery of the aperture. The head is placed over the base, and the locking means are inserted between the base and the periphery of the aperture, such that the locking means extend to a position on a lower side of the board. The locking means may then engage the periphery of the aperture on the lower side of the board, such that the locking means can lock the lower end of the head to the board, the base being secured between the head and the board. The invention includes a method of attaching a socket to a board, the method comprising the steps of: forming an aperture in the board; inserting a socket base from a position at an upper side of the board, through the aperture such that a portion of the socket base projects through the aperture and extends beyond a lower side of the board; presenting a socket head at a position at an upper side of the board, and engaging said socket head with said board, such that a portion of said socket head passes through said aperture between a periphery of said aperture and said base, and engages the board, such that a portion of said base is secured to the board on the upper side of the board, between said head and said upper side. Preferably, said locking means comprise first and second arms extending from said lower end of the socket head. A said arm preferably comprises a tapered portion, tapered in a direction substantially along a main length of the socket head. Preferably, said first and second arms are each provided with a said tapered portion, first and second arms capable of initially adopting a first position in which said first and second arms are spaced apart from each other by a first distance, and the arms being deformable when passing through a said aperture, such that the first and second arms move towards each other, and thereafter, once said first and second arms are inserted into the aperture, said first and second arms may return substantially to said first position, by moving away from each other. Preferably said tapered portions are arranged to engage an underside of said board when socket head is engaged with said board. Preferably said socket head comprises first and second housing portions contained within said tubular member, said first and second housing portions surrounding respective first and second cavities. Preferably, said electrical connector pins are arranged to be a close fit within said corresponding first and second cavities. Preferably, an upper end of said tubular member extends beyond an upper end of a said housing, by a distance in the range 5-20mm, and preferably at least 11.5mm. Preferably, a crimp portion of a said female connector pin, is completely contained within a said passage in said base in use. Preferably, said socket head is provided at a lower end thereof, with a downwardly projecting locating lug for locating with said socket base. Preferably said locating lug is provided with a skirt portion for surrounding said pin seating portions. Preferably said tubular member is provided on an internal surface thereof with an elongate spline extending in a direction parallel to a main length of the tubular member. According to a second aspect of the present invention, there is provided a plug for an electrical cable, said plug comprising a cap portion surrounding an end of said cable; a plurality of electrical connector pins, one said connector pin being electrically bonded to an earth conductor of said cable and another said electrical connector pin being connected with a signal conductor of said cable; the arrangement being that said pins extend in a direction transverse to a main length of said cable, said pins being surrounded by an insulating tubular sheath which extends beyond a lower extremity of said pins, in a direction transverse to said main length of cable. Preferably, said sheath extends beyond a lower extremity of a connector pin, by a distance in the range 3-lOmm, and preferably at least 6.5mm. Preferably, said plug is formed of an inner portion which is formed in a first forming operation, and an outer portion which is formed in a second forming operation. Preferably said first and second forming operations comprise moulding operations. Preferably said plug comprises a nylon moulding. Preferably an outer surface of said sheath is provided with a channel for engaging a said spline of the socket head, the arrangement being that the spline of the socket head engages the channel on the sheath, thereby ensuring that a first male connector pin engages a first female connector pin and a second male connector pin engages a second female connector pin. For a better understanding of the invention, and to show how embodiments of the same may be carried into effect, reference will now be made, by way of example, to the accompanying diagrammatic drawings, in which: Figure 1 shows in cut away view from the side, a socket according to a first specific embodiment of the present invention, engaged with a printed circuit board; Figure 2 shows in exploded view an assembly of the socket of figure 1, with the plug and the printed circuit board; Figures 3 to 6 show respectively in under side view, plan view, side view, and cut away end view a base of the socket; Figure 7 shows in expanded view a pin seating portion of the base; Figure 8 shows in perspective view a female pin connector comprising the base; Figure 9 shows in cut away end view a head portion of the socket; Figure 10 shows in expanded view a locking portion of the socket head; Figure 11 shows in expanded view a detail of an upper end of the socket head; Figure 12 shows in side view the socket head; Figure 13 shows in plan view the socket head, and figure 13a shows in expanded view a portion of an upper end of the socket head; Figure 14 shows in cut away side view the socket head; Figure 15 shows in cut away side view a plug according to a second specific embodiment of the present invention; Figure 16 shows in end view the plug of figure 15; Figure 17 shows in plan view the plug of figure 15; and Figure 18 shows from an underside, the plug of figure 15. Referring to figures 1 to 17 of the accompanying drawings, and initially to figures 1 and 2, a plug and socket assembly for fitment to a printed circuit board comprises a socket base 1, a socket head 2, and a plug 3. Referring to figures 3 to 8 of the accompanying drawings, there will now be described the socket base. The socket base comprises for example a nylon base moulding 10 having a base width a, a base length b and a base height c, an upper end of the base having a peripheral seating rim 11, extending around a perimeter of the base, and the base being provided with first and second passages 12, 13 each arranged for receiving a corresponding first or second female electrical connector pin, 20 as shown in figure 8. The passages 12, 13 have a main length which extends in a direction transverse, and in particular perpendicular, to a plane defining a seating surface 15 on a lower side of the seating rim 11. The passages extend between an upper end of the base and a lower end of the base. The passages comprise a first substantially cylindrical section 16, and a second, substantially frusto conical section 17, as shown particularly in figures 5, 6 and 7. At the upper end of each passage is provided a pin seating portion 19. The pin seating portion in the form of a first and second arcuate walls 21, 22 respectively defining the frusto conical section 17 of the passage. The first and second walls 21, 22 are separated from each other such that they face opposite sides of the passage. The first and second walls are deformable from, and normally return to their frusto conical shape, in which they are originally formed. The electrical connector pin 20 comprises a female crimp pin formed by rolling a sheet of resilient metal into a tubular form, to provide a female socket portion 30, and at an upper end of the pin and a crimp portion 31 at a lower end of the pin. Between the female socket portion and the crimp portion is provided a protruding ring portion 32, of diameter larger than the diameter of the female socket portion. In use, the female pin may be inserted into a said passage 12 or 13 in the base, by inserting the female socket portion 30 of the pin at an upper end of the pin into a lower end of the passage 12 or 13 at the lower end of the base, and pushing the pin in a direction along the passage towards the pin seating portion 19, such that the female socket portion 30 of the pin passes through the pin seating portion, splaying the first and second side walls 21, 22 of the pin portion apart as the ring portion 32 passes through the pin seating portion, the pin seating portion then contracting, as the ring portion passes out of the upper end of the passage, such that the electrical pin seats on top of the pin seating portion 19, the ring 32 resting on top of the ring seating portion and preventing the pin from being drawn back into the passage in a direction from the upper end of the base to the lower end of the base. The crimp portion 31 remains contained within the cylindrical portion 16 of the passage. Since the crimp portion 31 is crimped around an electrical wire, and may be soldered to the electrical wire, when the pin 20 is inserted into the passage 12 or 13, and passed out of the upper end of the passage, so that the ring portion passes through the seating portion 19, if the pin passes too far through the passage, the pin may be withdrawn back towards the passage by pulling the wire connected to the crimping portion 31, such that the ring 32 seats on an upper periphery of the seating portion 19. Referring to figures 9 to 13 of the accompanying drawings, there is shown the socket head 2. The head comprises an insulating tubular wall 30 moulded from, from example nylon, the tubular wall closed at a lower end 31 thereof by a floor portion 32 which extends across the lower end of the tubular portion 30, the tubular portion having a substantially oval cross section, the oval cross section comprising first and second semi circles spaced apart and placed oppositely from each other and separated by a linear portion extending between said first and second semi circles, as shown in plan view in particular in figure 13; the lower end 31 of the socket head being provided with first and second locking portions 34, 35 respectively each locking portion comprising an extending arm of a first thickness, having a foot portion of a second, larger thickness, the foot portion comprising a tapered portion, becoming thicker towards a lower extremity of the foot portion 36, the tapered portion as viewed in cross section forming a wedge, the wedge having a lower point extending in a direction along a main length of the head and facing outwardly away from the tubular body; internally of the tubular body are provided first and second substantially cylindrical pin housings 37, 38 each having a central cavity 39, 40 respectively for receiving a female socket portion of a respective said connector pin, the tubular member additionally being provided on one side, with an elongate spline 41 extending along the length of the head and internally of the tubular member, as shown particularly with reference to figure 13a, for ensuring that the plug is fitted into the socket in a predetermined manner such that connection is made to the first and second female pins in the correct electrical polarity. Referring to figures 15 to 18 respectively, there is shown the plug. The plug is moulded around an end of a conventional coaxial cable 50 having an outer sheath 51 surrounding concentrically an earth shielding, and contained within the earth shielding an insulator portion 53 surrounding concentrically a central conductor 54. The plug comprises a moulded cap portion 55 the cap portion being moulded in two parts being a first, inner moulded part 54, which is moulded around the end of the coaxial cable, and a second, outer moulded part 57 which is moulded around the inner moulded part. The outer moulded part includes an elongate tubular sheath 59 surrounding first and second substantially cylindrical cavities 60, 61 respectively. Concentrically with each cavity are provided a first and second male connector pin, the first male connector pin being electrically connected with the inner conductor 54 of the coaxial cable prior to moulding the cap, and the second male pin being electrically connected with the earthing sheath of the coaxial cable, prior to moulding the head. The tubular sheath 59 extends in a direction perpendicular to a main axis of the coaxial cable, such that connection of a coaxial cable to a printed circuit board may be made with the coaxial cable extending substantially parallel to a main plane of the printed circuit board, when the plug is inserted in the socket as previously described here above. Additionally, the tubular sheath 59 is formed having a channel 63 positioned between the first and second male pins, the channel 63 arranged to engage with the spline 41 of the socket head, to ensure that the first and second male pins engage the respective first and second female pins, and that the plug cannot be inserted into the head of the socket the wrong way engaging the second male pin with the first female pin. This ensures that the earth shielding of the coaxial cable is connected to a corresponding earthed female pin of the socket. Fitment of the socket to a printed circuit board will now be described with reference to figures 1 to 18 of the accompanying drawings. Referring in particular to figures 1 and 2, an aperture 80 is formed in a printed circuit board 81, the aperture being of dimension such that it closely fits around a perimeter of the base 1. The base is dropped or mechanically placed into the aperture in a direction from above the circuit board, such that the base protrudes through the circuit board, but is prevented from passing completely through the circuit board by the seating rim 11 which sits on the upper surface of the board around the perimeter of the upper end of the base. The socket head is then aligned such that the lower locating lug 45 of the head portion locates within the seating rim 11 of the base, the locking arms 34, 35 respectively on either side of the head, being inserted between the base and the PCB, and through the aperture 80 in the printed circuit board, such that the tapered portions 34, 35 of the locking arms extend through the aperture and to a position below an underside of the printed circuit board. In this position, the locking arms, which are urged slightly towards each other when passing through the aperture, may expand away from each other their original configuration as formed, thus causing the thicker end of the tapered wedge portions to contact the underside of the printed circuit board at the periphery of the aperture 80, thereby preventing the tapered portions from returning back through the aperture, and thereby locking the lower end of the head to the PCB. Since the base is positioned between the head portion and the PCB, but is prevented from passing through the PCB by virtue of the seating rim 11, the locking arms lock the head portion and the base portion of the socket to the PCB. Once the base and head are located to the PCB, the first and second female pin connectors may be passed from underneath the PCB, through the lower end of the passages 12, 13 in the base of the socket and, such that the ring 31 on the female pin passes through the pin seating 19, through which it cannot return, the female crimp portion of the female pin being housed within the pin housing 40 of the head portion. The plug 3 may then be inserted into the head of the socket, and pushed down such that the male pins engage the corresponding respective female pin connectors to make firm mechanical and electrical contact between the plug and socket, thereby ensuring firm electrical and mechanical contact between the coaxial cable and the printed circuit board. The provision of the locking arms 34, 35, the guidance spline 41 and corresponding channel in the plug sheath, and the protrusion 70 on the outer surface of the pin sheath, ensures a snap fit between the base, head and plug. As shown in figure 1, the plug and socket may be contained within a casing 100, the casing having an aperture 101 through which the upper end of the head may pass, the casing locating on an upper peripheral seating rim 102 formed around an outer surface of the tubular portion of the head. An upper end of the head is arranged to be flush with the outer surface of the casing. In use, the outer surface of the casing is accessible to a person and since the first and second female pins are provided within the tubular socket head, in the pin housings, and the pin housings and female pins are positioned at a depth of at least 11.5mm from the upper end of the socket head, a user is protected from accidentally contacting the female pins when the plug is not connected. Further, since the male pins are enclosed within the insulating sheath 59 of the plug, there being a distance of at least 6.5mm between the tip of the male pins and the lower end of the sheath, the chances of accidentally contacting the male pins and thereby incurring electric shock, are reduced. Specific embodiments of the present invention may have an advantage of providing a socket which can be quickly and easily fitted to a printed circuit board from a position above the printed circuit board, and which is suitable for automated connection of the socket to the printed circuit board. Further, specific embodiments may provide an advantage of providing a socket which is physically shielded, having pins protected from accidental contact due to the inaccessibility of the female pins from a position outside the socket, for anything except the matching plug. The reader's attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings) , and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) , may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features. The invention is not restricted to the details of the foregoing embodiment(s) . The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings) , or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims: CLAIMS 1. A board mountable electrical socket comprising: a socket base; and a socket head, wherein the socket head comprises locking means for locking the socket head to the board, the arrangement being that in use, the socket base is secured to the board by placing the socket base between the socket head and the board, and locking the socket head to the board. 2. A socket according to claim 1, wherein, the socket is adapted for fitment to a printed circuit board. 3. A socket according to claim 1 or 2, wherein the socket base comprises means for seating the base in an aperture in the board. 4. A socket according to claim 3, wherein said seating means comprises a rim extending around an upper end of the base. 5. A socket according to claim 3 or 4, wherein the socket base is adapted for receiving a first plurality of electrical connectors. 6. A socket according to claim 5, wherein said base is provided with a plurality of passages extending through the base, each said passage arranged for receiving a said electrical connector. 7. A socket according to claim 5 or 6, wherein a said electrical connector comprises a connector pin. 8. A socket according to claim 7, wherein the connector pin is preferably a female connector pin. 9. A socket according to claim 7 or 8 wherein said connector pin comprises a crimp connector. 10. A socket according to claim 9 as appendant to claim 8 , wherein a crimp portion of a said female connector pin, is completely contained within a said passage in said base in use. 11. A socket according to claim 7, 8, 9 or 10 wherein a said passage is arranged such that a said electrical connector pin may be inserted into the passage from a lower end of said passage, and pushed through said passage, so as to partially protrude from an upper end of said passage, a portion of said electrical connector pin remaining in said passage. 12. A socket according to claim 11, wherein said passage is surrounded or partially surrounded by a pin seating portion. 13. A socket according to claim 12, wherein the pin seating portion is arranged around a periphery of said passage such that said pin seating portion may expand when a said electrical connector pin passes through said passage in a first direction, and may contract thereafter, thereby preventing passage of said electrical connector pin in a second direction, opposite to said first direction. 14. A socket according to claim 12 or 13, wherein a said pin seating portion comprises a substantially tubular portion surrounding said passage. 15. A socket according to any of the preceding claims, wherein said socket head comprises a substantially tubular member having a lower end arranged to engage said socket base portion, said lower end being provided with said locking means for locking the lower end of said socket head to a board. 16. A socket according to claim 15, wherein said tubular member is provided on an internal surface thereof with an elongate spline extending in a direction parallel to a main length of the tubular member. 17. A socket according to any of the preceding claims, wherein, in use, where the socket is to be fitted to a board, for example a printed circuit board, an aperture is formed in the printed circuit board the aperture having a periphery of a shape which closely fits the base, such that the base may be inserted through the aperture from a position at an upper side of the board, the base being prevented from passing completely through the aperture by a seating rim at the upper end of the base, the seating rim arranged to locate around the periphery of the aperture. 18. A socket according to claim 17, wherein the head is placed over the base, and the locking means are inserted between the base and the periphery of the aperture, such that the locking means extend to a position on a lower side of the board. 19. A socket according to claim 18, wherein the locking means are adapted, in use, to engage the periphery of the aperture on the lower side of the board, such that the locking means can lock the lower end of the head to the board, the base being secured between the head and the board. 20. A socket according to claims 17, 18 or 19, wherein said locking means comprise first and second arms extending from said lower end of the socket head. 21. A socket according to claim 20, wherein a said arm comprises a tapered portion, tapered in a direction substantially along a main length of the socket head. 22. A socket according to claim 21, wherein said first and second arms are each provided with a said tapered portion, first and second arms capable of initially adopting a first position in which said first and second arms are spaced apart from each other by a first distance, the arms being deformable when passing through a said aperture, such that the first and second arms move towards each other, and thereafter, once said first and second arms are inserted into the aperture, said first and second arms may return substantially to said first position, by moving away from each other. 23. A socket according to claims 19 or 22, wherein said tapered portions are arranged to engage an underside of said board when the socket head is engaged with said board. 24. A socket according to claim 15, or any of claims 16 to 23 as appendant thereto, wherein said socket head comprises first and second housing portions contained within said tubular member, said first and second housing portions surrounding respective first and second cavities. 25. A socket according to claim 24, wherein said electrical connector pins are arranged to be a close fit within said corresponding first and second cavities. 26. A socket according to claim 24 or 25, wherein an upper end of said tubular member extends beyond an upper end of a said housing, by a distance in the range 5-20mm, and preferably at least 11.5mm. 27. A socket according to any of the preceding claims, wherein said socket head is provided at a lower end thereof, with a downwardly projecting locating lug for locating with said socket base. 28. A socket according to claim 27, wherein said locating lug is provided with a skirt portion for surrounding said pin seating portions. 29. A plug for an electrical cable, said plug comprising a cap portion surrounding an end of said cable; a plurality of electrical connector pins, one said connector pin being electrically bonded to an earth conductor of said cable and another said electrical connector pin being connected with a signal conductor of said cable; the arrangement being that said pins extend in a direction transverse to a main length of said cable, said pins being surrounded by an insulating tubular sheath which extends beyond a lower extremity of said pins, in a direction transverse to said main length of cable. 30. A plug according to claim 29, wherein said sheath extends beyond a lower extremity of a connector pin, by a distance in the range 3-lOmm, and preferably at least 6.5mm. 31. A plug according to claim 29 or 30, wherein said plug is formed of an inner portion which is formed in a first forming operation, and an outer portion which is formed in a second forming operation. 32. A plug according to claim 31, wherein said first and second forming operations comprise moulding operations. 33. A plug according to claim 32, wherein said plug comprises a nylon moulding. 34. A plug according to any of claims 29 to 33, wherein an outer surface of said sheath is provided with a channel which is specially adapted for engaging a said spline of the socket head of the socket of claim 16, or of any of claims 17 to 28 as appendant to claim 16, the arrangement being that the spline of the socket head engages the channel on the sheath, thereby ensuring that a first male connector pin engages a first female connector pin and a second male connector pin engages a second female connector pin. 35. A method of attaching a socket to a board, the method comprising the steps of: forming an aperture in the board; inserting a socket base from a position at an upper side of the board, through the aperture such that a portion of the socket base projects through the aperture and extends beyond a lower side of the board; presenting a socket head at a position at an upper side of the board, and engaging said socket head with said board, such that a portion of said socket head passes through said aperture between a periphery of said aperture and said base, and engages the board, such that a portion of said base is secured to the board on the upper side of the board, between said head and said upper side.

Inventors: RAWSTHORNE BRIAN, RAWSTHORNE, BRIAN
Applicants: LEM HEME LTD, RAWSTHORNE BRIAN, LEM HEME LIMITED, RAWSTHORNE, BRIAN
Application year: 1996
Main classification: H01R13
IPC codes: H01R12, H01R13