BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will be discussed below in detail with reference to the accompanying drawings, in which:
FIG. 1 is a perspective view of a receptacle which serves as an element of an embodiment of a connector according to the present invention, showing the overall structure of the receptacle;
FIG. 2 is a cross sectional view of a receptacle contact of the receptacle shown in FIG. 1, showing the configuration thereof;
FIG. 3 is a perspective view of a plug which serves as an element of the embodiment of the connector according to the present invention, showing the overall structure of the plug;
FIG. 4 is a cross sectional view of a plug contact of the plug shown in FIG. 3, showing the configuration thereof;
FIG. 5A is a cross sectional view of the receptacle shown in FIG. 1 and the connector shown in FIG. 3 (taken along a plane extending in the insertion/extraction direction of the plug relative to the receptacle), showing a state immediately after the plug commences to be inserted into the receptacle;
FIG. 5B is a cross sectional view similar to FIG. 5A, showing a state in which the insertion of the plug into the receptacle has been completed; and
FIG. 6 is a view similar to those of FIGS. 5A and 5B, showing a state immediately after the plug commences to be extracted from the receptacle.
DESCRIPTION OF THE PREFERRED EMBODIMENT
An embodiment of a connector according to the present invention is provided with a receptacle 1 (shown in FIG. 1) and an associated plug 2 (shown in FIG. 3) which are engaged with each other to be electrically connected to each other. For instance, one of the receptacle 1 and the plug 2 is mounted to an LCD (liquid display device/ display device) unit or a CCD (charge coupled device/ image pickup device) unit, while the other of the receptacle 1 and the plug 2 is mounted to a board (e.g., circuit board) which is electrically connected to the LCD unit or the CCD unit to control operations thereof. The LCD unit or the CCD unit is electrically connected to the board by the engagement of the plug 2 with the receptacle 1. The receptacle 1 and the plug 2 can be adopted for establishing electrical connection within portable terminal equipment (e.g., a cellular phone, a PDA (personal digital assistant) such as a mobile computer and the like) or electrical connection between portable terminal equipment and external equipment. In addition to an LCD unit, the receptacle 1 and the plug 2 can be adopted for use in the following display units: a CRT (cathode-ray tube) display unit, a plasma display unit and an organic EL (electroluminescent) display unit. Moreover, in addition to a CCD unit, the receptacle 1 and the plug 2 can be adopted for use in a CMOS (complementary metal oxide semiconductor) unit.
As shown in FIG. 1, the receptacle 1 is provided with a receptacle body 3 and a plurality of receptacle contacts 4, i.e., two arrays of receptacle contacts 4. The receptacle body 3 is molded from an electrical-insulating synthetic resin, e.g., 9T Nylon (trademark), a modified nylon or a liquid crystal polymer by injection molding, and is provided with an insertion groove 31, into and from which the plug 2 is plugged and unplugged. The insertion groove 31 is provided with a bottom wall 32, a side wall 31a and an inner wall 35 (see FIGS. 5A and 5B). The two arrays of receptacle contacts 4 are arranged on opposite sides of the insertion groove 31.
As shown in FIG. 2, each receptacle contact 4 is molded of metal by stamping so as to be formed in a strip shape, and is provided with a retaining portion 40, a connecting portion 50, a plug-contact contacting portion 55 and an inner-wall-contacting portion 60 which are continuously formed as an integral member. In the following description, the side on which the plug 2 is positioned and another side on which the receptacle 1 is positioned when the plug 2 is inserted into the receptacle 1 are referred to as the upper side and the lower side (the upper side and the lower side as viewed in FIG. 2), respectively.
The retaining portion 40 is U-shaped and is held by the receptacle body 3 in a manner so that the side wall 31a (see FIGS. 5A and 5B) of the insertion groove 31 interposes the retaining portion 40. The connecting portion 50 extends in the widthwise direction of the receptacle 1 (i.e., a direction orthogonal to the lengthwise direction of the insertion groove 31) from one end of the retaining portion 40 which is positioned inside the insertion groove 31. The plug-contact contacting portion 55 is formed as an S-shape in which the receptacle contact 4 firstly bends upward from one end (the left end as viewed in FIG. 2) of the connecting portion 50, subsequently bends back toward a central portion 43 of the retaining portion 40 and thereafter bends in a direction away from the central portion 43.
The retaining portion 40 consists of an outer portion 41, the central portion 43 and a horizontal connecting portion 42. The outer portion 41 extends in the insertion/extraction direction of the plug 2 (which includes both the direction to insert the plug 2 into the insertion groove 31 and the direction to extract the plug 2 from the insertion groove 31). The central portion 43 extends in substantially the same direction as the outer portion 41 to face the outer portion 41. The horizontal connecting portion 42 extends in a direction orthogonal to both the directions of extension of the outer portion 41 and the central portion 43 to connect upper ends of the outer portion 41 and the central portion 43 which are opposed to each other. Each receptacle contact 4 is provided with a terminal portion 44 which is formed integral with the receptacle contact 4 to project outward (rightward as viewed in FIG. 2) from the lower end of the outer portion 41 that is positioned outside of the insertion groove 31 and to project from the bottom end of a side face of the receptacle 3 which extends in the lengthwise direction of the receptacle 3. The terminal portion 44 can be fixed to a conductive pattern formed on a circuit board by, e.g., soldering.
It is desirable that at least one of the outer portion 41 and the central portion 43 of each receptacle contact 4 be provided, at a substantially center thereof in the insertion/extraction direction of the plug 2, with lock lugs (not shown) which project in the opposite directions away from each other along the widthwise direction of the receptacle contact 4, respectively. Such lock lugs are engaged with corresponding engaging portions (not shown) formed on the receptacle body 3 upon the plug contact 4 being mounted to the receptacle body 3. With this structure, the receptacle contact 4 is securely fixed to the receptacle body 3.
In the present embodiment, the receptacle contacts 4 are extremely thin (e.g., 0.1 mm or less), and all the receptacle contacts 4 have a uniform thickness.
However, the following alternative structure is possible. Namely, the central portion 43 can be provided, in an area thereof extending from the end of the central portion 43 on the horizontal connecting portion 42 side to a substantially center of the central portion 43 in the insertion/extraction direction of the plug 2, with a holding projection 43a which projects in a direction away from the outer portion 41. The holding projection 43a can be press-formed at a lower half of the central portion 43 (which is identical in thickness to the terminal portion 44, the outer portion 41 and the horizontal connecting portion 42) from a substantially center of the central portion 43 in the insertion/extraction direction of the plug 2 so as to reduce the thickness of the holding projection 43a. In addition, the dimensions of the holding projection 43a and the installation position thereof in the insertion/extraction direction of the plug 2 can be adjusted by stamping the holding projection 43a from the back (the surface on the outer portion 41 side) using a die. The thin portion having been made thin by the aforementioned press-forming process is identical in thickness to the connecting portion 50 and the plug-contact contacting portion 55. This kind of thickness distribution strengthens the fixing of the retaining portion 40 and the terminal portion 44 relative to the receptacle body 3 and effectively disperses the stress which is transmitted to the receptacle contact 4 by displacements (deformation) thereof when the plug 2 is inserted into and removed from the receptacle body 3 to thereby prevent a plastic deformation of the receptacle contact 4 from occurring. Accordingly, when each receptacle contact 4 is installed to the receptacle body 3, the outer portion 41 and the horizontal connecting portion 42 can be prevented from being deformed. Moreover, stress becomes harder to be transmitted to the terminal portion 44, and accordingly, the receptacle body 3 and solder for use in joining metallic surfaces can be prevented from becoming cracked when the terminal portion 44 is fixed to the receptacle body 3 and when the terminal portion 44 is fixed to a conductive pattern formed on a circuit board by soldering.
The connecting portion 50 consists of a horizontal connecting portion 51 and a first resilient bendable portion 52. The horizontal connecting portion 51 extends in a direction parallel to the direction of extension of the horizontal connecting portion 42 that extends from the upper end of the central portion 43 of the retaining portion 40. The first resilient bendable portion 52 extends from the left end (as viewed in FIG. 2) of the horizontal connecting portion 51 obliquely upward in a direction gradually away from a horizontal plane in which the horizontal connecting portion 51 lies. It is possible that the horizontal connecting portion 51 and the first resilient bendable portion 52 be integrally formed as a single curved portion which extends obliquely upward in a direction gradually away from a horizontal plane in which the horizontal connecting portion 51 lies.
The plug-contact contacting portion 55 consists of a second resilient bendable portion 56, a contact projection portion 58 and a horizontal portion 59 to be formed in the shape of a substantially letter S as a whole. The second resilient bendable portion 56 is bent to extend back toward the central portion 43 from the inner end (left end as viewed in FIG. 2) of the first resilient bendable portion 52. The contact projection portion 58 firstly extends in a direction away from the connecting portion 50 from the upper end of the second resilient bendable portion 56 while approaching the central portion 43, and is subsequently bent to extend in a direction away from the central portion 43 to thereby form a curved projection portion 58a. The horizontal portion 59 extends from the contact projection portion 58 in a direction parallel to the direction of extension of the horizontal connecting portion 51. The first resilient bendable portion 52 and the second resilient bendable portion 56 can be integrally formed in the shape of a single circular arc corresponding to a part of a circle having a constant radius. Forming the plug-contact contacting portion 55 in an S-shape to include a plurality of curved surfaces in this manner makes it possible to form a curved surface with a large radius of curvature, thus making it possible to improve the spring resiliency of the plug-contact contacting portion 55 itself. In addition, connecting the plug-contact contacting portion 55 to the first resilient bendable portion 52 makes it possible for the plug-contact contacting portion 55 to be resiliently deformed in association with the resilient deformation of the connecting portion 50. Therefore, each receptacle contact 4 can make full use of the spring resiliency thereof even in the case of the connector in which space is limited due to a height reduction of the connector.
The inner-wall-contacting portion 60 extends from the inner end (left end as viewed in FIG. 2) of the horizontal portion 59 of the plug-contact contacting portion 55 in a direction away from the retaining portion 40. The inner-wall-contacting portion 60 is provided with an inclined portion 61, an end portion 63, and a bent portion 62 formed between the inclined portion 61 and the end portion 63. The inclined portion 61 extends toward the inner wall 35 of the receptacle body 3 (see FIGS. 5A and 5B) while approaching the bottom wall 32 of the receptacle body 3 in a state where the receptacle contact 4 is held by the receptacle body 3. The end portion 63 extends in a direction substantially parallel to the inner wall 35 of the receptacle body 3 (i.e., along the insertion/extraction direction of the plug 2) from the bent portion 62, that is formed at the lower end of the inclined portion 61, to face the inner wall 35. The end portion 63 can extend in a direction not parallel to the inner wall 35, e.g., can extend from the bent portion 62 in a direction obliquely toward the bottom wall 32 of the receptacle body 3 while gradually approaching the plug-contact contacting portion 55.
Each receptacle contact 4 is made of a base material (e.g., beryllium copper, titanium copper, phosphor bronze or Corson (Ni—Si) copper alloy) on which firstly a base coating (e.g., nickel coating) is plated and subsequently a finishing coating (e.g., gold coating) is plated. In the case where each array of receptacle contacts 4 (each array of plug contacts 7 shown in FIG. 3) are arranged with a pitch of 0.3 mm through 0.5 mm, it is desirable that the thickness of each of the retaining portion 40, the terminal portion 44 and the holding projection 43a be in the range of 0.08 mm through 0.15 mm and that the thickness of each of the portion of the central portion 43 (other than the holding projection 43a), the connecting portion 50, the plug-contact contacting portion 55 and the inner-wall-contacting portion 60 be in the range of 0.05 mm through 0.08 mm from the viewpoint of spring design and workability in consideration of miniaturization of the connector and the reduction of the height thereof. In this particular case, it is desirable that the thickness of the base coating be in the range of 0.5 through 4.0 micrometers. This range is determined due to the fact that the effectiveness of the base coating becomes invalid if the thickness of the base coating is below 0.5 micrometers and that the base coating becomes cracked easily by a deformation thereof when the base coating is in sliding contact with the associated plug contact 6 of the plug 2 if the thickness of the base coating exceeds 4.0 micrometers. In addition, in the case where the finishing coating is gold, it is desirable that the thickness of the finishing coating of each of the retaining portion 40, the connecting portion 50, the plug-contact contacting portion 55 and the inner-wall-contacting portion 60 be in the range of 0.03 mm through 0.5 micrometers and that the thickness of the finishing coating of the terminal portion 44 be in the range of 0.03 mm through 0.2 micrometers. This is determined due to the fact that, if the thickness of the finishing coating of the terminal portion 44 exceeds 0.2 micrometers, solder (e.g., tin-lead, tin-copper, or tin-copper-silver) for use in soldering the terminal portion 44 to a conductive pattern on a circuit board becomes easier to diffuse, which causes the strength of the connection by soldering to deteriorate, thus causing the solder to become cracked easily.
When the receptacle contacts 4 are mounted to the receptacle body 3, each receptacle contact 4 is inserted into the receptacle body 3 from the upper side thereof, and is pressed-fitted into the insertion groove 31 (the side wall 31a) formed in the receptacle body 3 whereby each receptacle contact 4 is held. This fixing manner is possible because each receptacle contact 4 does not have to be inserted into the receptacle body 3 from the lower side thereof since a high holding force for holding the engagement of the receptacle 1 with the plug 2 is achieved by the formation of the inner-wall-contacting portion 60. Accordingly, the receptacle body 3 does not have to be provided in the bottom wall 32 thereof, on which the two arrays of receptacle contacts 4 are to be mounted, with two corresponding arrays of through holes in which the two arrays of receptacle contacts 4 are inserted, //respectively.
Moreover, although through holes are made in the bottom wall of the receptacle body due to limiting factors of the molding dies used for molding the pair of movement preventive portions in the connector disclosed in the aforementioned Japanese Unexamined Patent Publication 2001-338711, the receptacle body 3 can be molded without making any through holes in the bottom wall 32 because there is no need for the receptacle body 3 to be provided with movement preventive portions corresponding to those formed on the receptacle body disclosed in Japanese Unexamined Patent Publication 2001-338711.
Therefore, in the present embodiment of the connector, the conductive-pattern-formation impermissible area (in which formation of conductive patterns is not permitted) on a circuit board to which the receptacle body 3 is mounted can be reduced while intrusion of flux and other foreign particles in the receptacle body 3 can be prevented since no through holes are formed in the bottom wall 32 of the receptacle body 3.
The bottom wall 32 (see FIGS. 5A and 5B) of the receptacle body 3, which is positioned below the horizontal connecting portion 51 and the first resilient bendable portion 52 of each receptacle contact 4 when the receptacle contact 4 is fixed to the receptacle body 3, is positioned with a predetermined slight gap between the bottom wall 32 and the horizontal connecting portion 51 in a state where the plug 2 is not engaged in the receptacle 1. It is desirable that this gap be in the range of 0.01 through 0.05 mm. Note that this gap is not shown in the drawings. Products beyond tolerance are produced (i.e., the bottom wall 32 and the horizontal connecting portion 51 are in contact with each other in one connector and not in contact with each other in another connector) due to manufacturing variations if the gap is set below 0.01 mm, and the behavior of each receptacle contact 4 as a spring becomes unstable to thereby make it impossible to obtain a predetermined contact pressure if the gap exceeds 0.05 mm.
Upon each plug contact 7 being engaged in the associated receptacle contact 4, at least the horizontal connecting portion 51, from among the horizontal connecting portion 51 and the first resilient bendable portion 52, comes into contact with the bottom wall 32, which stabilizes the behavior of the receptacle contact 4. Namely, since the variation of the shape of the receptacle contact 4 is limited by the bottom wall 32, plastic deformation of the receptacle contact 4 can be prevented from occurring. In addition, wiring can be carried out even below the receptacle 1 because the insulating bottom wall 32 is positioned below the two arrays of receptacle contacts 4.
The plug 2 that is shown in FIG. 3 is provided with a plug body 5 formed in the shape of a substantially rectangular parallelepiped, and a plurality of plug contacts 7, specifically, two arrays of plug contacts 7 which are arranged to correspond to the two arrays of receptacle contacts 4. The plug body 5 is molded of an electrical-insulating synthetic resin by insert molding, and each array of plug contacts 7 is arranged with the same pitch as the associated array of receptacle contacts 4. The plug body 5 is an insulating member molded integrally with the two arrays of plug contacts 7 from, e.g., 9T Nylon (trademark), amodified nylon or a liquid crystal polymer by insertion molding.
As shown in FIG. 4, each plug contact 7 is molded of metal by stamping so as to be formed in a strip shape, and is provided with a first contacting portion 71, a second contacting portion 72 and a connecting portion 73 which are continuously formed as an integral member. The first contacting portion 71 extends in the insertion/extraction direction of the plug 2. The second contacting portion 72 extends in substantially the same direction as the first contacting portion 71 to face the first contacting portion 71. The connecting portion 73 extends in a direction orthogonal to both the directions of extension of the first contacting portion 71 and the second contacting portion 72 to connect the lower end 71a of the first contacting portion 71 and the lower end 72a of the second contacting portion 72 to each other. A terminal portion 74 is formed integral with each plug contact 7, projects from the upper end 71b of the first contacting portion 71 and penetrates the plug body 5 to extend in a direction substantially parallel to the connecting portion 73. The terminal portion 74 can be fixed to a conductive pattern formed on a circuit board by, e.g. , soldering. Note that the two arrays of plug contacts 7 can be made of the same material as the two arrays of receptacle contacts 4 in a similar manner, hence, the method of forming the two arrays of plug contacts 7 will be omitted from the following description.
The first contacting portion 71 is provided, at the lower end 71a thereof on the connecting portion 73 side, with a projection 71d which projects in a direction away from the second contacting portion 72. With this configuration of the first contacting portion 71, a tactile feedback can be felt due to the projection 71d riding over the curved projection portion 58a upon the plug 2 being inserted into the receptacle 1, and the holding of each plug contact 7 to the associated receptacle contact 4 therein is ensured.
On the other hand, the second contacting portion 72 is provided with a projection 72b which projects in a direction away from the first contacting portion 71. With this configuration of the second contacting portion 72, a tactile feedback can be felt due to the projection 72b riding over the holding projection 43a upon the plug 2 being inserted into the receptacle 1, and the holding of each plug contact 7 to the associated receptacle contact 4 therein is ensured. Moreover, each plug contact 7 is in contact with the associated receptacle contact 4 at two points of contact (the point of contact between the second contacting portion 72 and the holding projection 43a and the point of contact between the first contacting portion 71 and the curved projection portion 58a) to be pinched by the associated receptacle contact 4, and accordingly, reliable electrical connection is established between each plug contact 7 and the associated receptacle contact 4.
In the present embodiment of the connector that has the above described structure, in the initial stage in the insertion operation of each plug contact 7 into the associated receptacle contact 4, the lower end 71a of the first contacting portion 71 is pressed against an upper portion of the contact projection portion 58, which causes the first resilient bendable portion 52 to approach the bottom wall 32 as shown in FIG. 5A. A further insertion of the plug contact 7 into the receptacle contact 4 causes the inner-wall-contacting portion 60 and the plug-contact contacting portion 55 to be resiliently deformed in the direction of extension of the horizontal connecting portion 51 so as to increase the distance between the holding projection 43a and the curved projection portion 58a. As a result, the bent portion 62 comes into (firm) contact with the inner wall 35 of the receptacle body 3 that extends in the insertion/extraction direction of the plug 7, and the first contacting portion 71 and the second contacting portion 72 are inserted in between the plug-contact contacting portion 55 and the retaining portion 40 as shown in FIG. 5B while causing the first contacting portion 71 and the second contacting portion 72 to slide on the contact projection portion 58 and the central portion 43, respectively.
In a state where the plug contact 7 is not inserted into the receptacle contact 4, the distance (gap) between the holding projection 43a and the curved projection portion 58a is constant (predetermined). This predetermined distance is smaller than the distance between the outer surfaces of the first contacting portion 71 and the second contacting portion 72 (the left and right surfaces of the first contacting portion 71 and the second contacting portion 72, respectively, as viewed in FIG. 5A and 5B). Therefore, upon each plug contact 7 being inserted into the associated receptacle contact 4, the distance between the holding projection 43a and the curved projection portion 58a of the receptacle contact 4 increases, and the plug contact 7 is held (pinched) by the receptacle contact 4 with the resiliency thereof. The predetermined distance between the holding projection 43a and the curved projection portion 58a can be set at any given distance according to a design value of the force holding the plug contact 7.
The behavior of each receptacle contact 4 when the plug 2 is inserted into and extracted from the receptacle 1 will be discussed hereinafter.
Firstly, when the plug 2 is inserted into the receptacle 1, the plug-contact contacting portion 55 is compressed from above by the engagement of the first contacting portion 71 with the curved projection portion 58a, so that the S-shape of the plug-contact contacting portion 55 is compressed, while the plug contact 7 enters in between the plug-contact contacting portion 55 and the retaining portion 40 while widening the gap between the holding projection 43a and the curved projection portion 58a, and accordingly, the plug-contact contacting portion 55 shifts toward the inner wall 35 of the receptacle body 3. Since the inner-wall-contacting portion 60 is provided with the inclined portion 61, and since an upper portion of the inner-wall-contacting portion 60 and the inner wall 35 do not come in contact with each other, the plug 2 can be inserted into the receptacle_1 by a relative small force.
The behavior of each receptacle contact 4 when the plug 2 is inserted into and extracted from the receptacle 1 will be discussed hereinafter.
When the plug 2 is extracted from the receptacle 1, each receptacle contact 4 attempts to move with the associated plug contact 7 in a direction to be disengaged therefrom because the plug contact 7 is pinched between the holding projection 43a and the curved projection portion 58a. Thereupon, the inner-wall-contacting portion 60 slightly rotates in the counterclockwise direction as viewed in FIG. 6 since the friction produced between the plug-contact contacting portion 55 and the first contacting portion 71 creates a torque urging the plug-contact contacting portion 55 to rotate in the counterclockwise direction as viewed in FIG. 6. Accordingly, the inner-wall-contacting portion 60 is in sliding contact with the inner wall 35, which prevents the gap between the holding projection 43a and the curved projection portion 58a from further widening. Additionally, even if the receptacle contact 4 attempts to be resiliently deformed to widen the gap between the holding projection 43a and the curved projection portion 58a, the plug contact 7 is securely held by the receptacle contact 4 since the inner-wall-contacting portion 60 is pushed back toward the plug contact 7 by the inner wall 35 by resiliency of the inner-wall-contacting portion 60. Namely, such a configuration makes it possible to achieve a high holding force for holding the engagement of the receptacle 1 with the plug 2. Moreover, this holding force can be adjusted by, e.g., reducing the thickness of the inner-wall-contacting portion 60 by crushing the inner-wall-contacting portion 60. Therefore, when the connector is handled, either the position of the inner-wall-contacting portion 60 or the receptacle contact 4 does not change excessively even if a load greater than expected is exerted on the connector, so that a plastic deformation of the receptacle contact 4 can be prevented from occurring. Consequently, the performance of the connector can be maintained with reliability.
On the other hand, when each plug contact 7 is extracted from the associated receptacle contact 4, an upward sliding movement of the projection 71d of the first contacting portion 71 on the curved projection portion 58a of the receptacle contact 4 produces a force lifting the plug-contact contacting portion 55 as shown in FIG. 6. Although this force increases in the case where the plug 2 is extracted obliquely from the receptacle 1, the receptacle contact 4 can be prevented from being curled up since the inner-wall-contacting portion 60 is resiliently deformed so that the bent portion 62 thereof is in elastic contact with the inner wall 35 of the receptacle body 3. Upon the extraction of the plug 2 from the receptacle 1 being completed, the gap between the holding projection 43a and the curved projection portion 58a of each receptacle contact 4 becomes small to return the receptacle contact 4 to a state before the insertion of the plug contact 7 into the receptacle contact 4 by the resiliency thereof.
As can be understood from the foregoing, in the present embodiment of the connector, the holding force for holding the engagement of the receptacle 1 with the plug 2 can be prevented from deteriorating while shavings and the like can be prevented from being produced by wear in the connector even if-the plug is repeatedly inserted into and extracted from the receptacle because the inner-wall-contacting portion 60 is made to contact the inner wall 35 while being resiliently deformed, rather than simply being made to engage with the inner wall 35. In addition, since the connector does not have any elements interfering with a reduction in height of the connector, a further reduction in height of the connector is achieved. Furthermore, when the connector is handled, neither the position of the inner-wall-contacting portion 60 nor the receptacle contact 4 changes excessively even if a load greater than would be expected is exerted on the connector since the inner-wall-contacting portion 60 and the inner wall 35 are in contact with each other, so that an elastic deformation of the receptacle contact 4 can be prevented from occurring, thereby the performance of the connector can be maintained with reliability.
In the above illustrated embodiment of the connector, the functions of each receptacle contact 4 and each plug contact 6 are reversible.
Obvious changes may be made in the specific embodiment of the present invention described herein, such modifications being within the spirit and scope of the invention claimed. It is indicated that all matter contained herein is illustrative and does not limit the scope of the present invention.
Patent Application
20070264854
