Electrical Contact Arrangement

1. Field of the Invention

The invention relates generally to electrical terminals and, more particularly, to a multiple-contact configuration for electrical engagement of a blade terminal within a mating receptacle.

2. Background of the Invention

Historically, various types of assemblies have been developed for electrically and conductively interconnecting devices to be electrically energized to sources of electrical power. For example, it is well known to provide various spatial areas of residential, commercial and industrial establishments with electrical receptacle units permanently (through fuses, circuit breakers or other emergency shut-off elements) conductively connected to one or more sources of main utility power. Each of the receptacle units typically comprises one or more engaging assemblies often referred to by the colloquial term "female receptacle."

These receptacle units are conventionally mounted in stationary walls or, alternatively, in the case of modern and modular office furniture systems, in moveable wall panels or even within work surfaces. Devices to be electrically energized often comprise receptacle plugs having two or more prongs or blade terminals adapted to be conductively engaged within the female receptacles. The prongs or blade terminals are conventionally referred to by the colloquial terms "male" plugs, prongs, blades or terminals. The receptacle plugs are typically interconnected to the circuitry of the device so as to be energized by wires extending through flexible insulative cords or the like.

This type of male/female electrical interconnection configuration to provide removable or releasable conductive engagement is utilized in a myriad of electrical connector arrangements. For example, in addition to electrical energization of relatively large and discrete devices (such as lamps, televisions, stereos, typewriters, etc.), male/female interconnection configurations are also utilized internally in electrical devices such as computers and associated peripherals. In addition, male/female electrical interconnection arrangements are also utilized in a number of other applications, such as internal circuit wiring for electrical apparatus of modular office systems and the like.

In the design of male/female electrical interconnection configurations, it is of primary importance to provide a secure and stationary electrical contact between the conductive surfaces of the elements of the electrical receptacle and the conductive surfaces of the prongs or blade terminals. It is also of primary importance to provide surface connections having relatively little resistance. In view of the foregoing, various types of interfaces have been developed for engaging male prongs or blade terminals with mating female receptacles. For example, it is known to utilize an opposing pair of cantilever beams within the female receptacle, which provide a single point of contact on each side of an inserted male terminal. Other known arrangements include the use of single cantilever spring pressure, backed with a steel or similar spring supported within a plastic housing. This type of arrangement will conventionally provide a single point of contact at the electrical interface.

It has become known that it is preferable to provide as many interface points of contact as is reasonably possible, while still maintaining a releasable engagement. For example, an arrangement for providing four contact points is disclosed in Sasaki et al, U.S. Pat. No. 4,795,379 issued Jan. 3, 1989. The Sasaki et al patent refers to the concept that it has been known to utilize certain types of electrical connections in computers, telecommunications equipment and other data processing equipment, which are in the form of a receptacle contact having four resilient cantilever contact members extending forwardly from a base. The contact members are adapted to provide an electrical connection with a tab contact inserted from the front of the receptacle unit. The tab contact is electrically engaged by four leaves from four directions. The four leaves can be arranged as opposing pairs, with each pair arranged orthogonally.

In this type of arrangement, electrical engagement is made with the tab contact at four points, thereby increasing reliability of the receptacle contact relative to a contact arrangement having only two contact points. Sasaki et al also explains that a problem can arise in that a possibility of an incomplete electrical engagement can be caused by foreign matter on the surface of the tab contact. In addition, one of the pairs of contact members may engage the edge surfaces of the tab contact. The edge surfaces of the tab contact are typically the surface edges formed when the contact is made by stamping a sheet of conductive material. The surfaces are often rough in comparison with the planar rolled or formed surface of the sheet, and thus have a lower contact reliability. Accordingly, these contact members may not provide a reliable electrical connection, and a greater insertion force may be required at the time of insertion.

As an improvement, Sasaki et al describes a receptacle contact having opposed leaf spring members formed by two parallel plates linked through a U-shaped portion extending between adjacent sides of the leaf spring members. The leaf spring members include first spring arms and second spring arms formed integrally with the spring members.

The first spring arms and second spring arms are opposed to each other, and outer contact and inner contact members are formed at the free ends of the spring arms, which are also opposed to each other. Additional contact members are located to the rear of the first set of contact members. The spring arms extend side by side from the leaf spring members, with the outer contact members being slightly twice the width of the inner contact members. The contact members are arcuate to facilitate insertion of a tab contact therebetween.

The receptacle contact described in Sasaki et al is formed by stamping from a suitable metal sheet having the desirable conductive and spring characteristics. The stamping process is performed by shaping the metal sheet in an appropriate configuration, and then folding the spring arms to the shape required, while folding another portion into a U-shape. In use, the tip of a tab contact can be inserted into the space between the outer contact members opposed to each other at the front portion of the receptacle contact. Upon insertion, upper and lower surfaces of the contact are brought into a wiping engagement with the outer contact members. Accordingly, foreign matter on upper and lower surfaces of the contact is removed. When the contact is inserted further, the upper and lower surfaces which have been cleaned by the outer contact members are also wipingly engaged by the inner contact members. In this manner, a relatively greater electrical connection reliability between the tab contact and the inner contact members is provided. In addition, the outer contact members and inner contact members are in electrical engagement with upper and lower planar surfaces of the tab contact, and not with side surfaces which may comprise the cut edge surfaces of the contact. Accordingly, this decreases the force needed to insert the contact into the receptacle contact, thereby improving reliability of electrical connection.

In addition, the length of the spring arms which provide the contact force created between the outer contact members and the tab contact, is longer than the length of the spring arms which provide the contact force between inner contact members and the tab contact. Accordingly, the insertion force is reduced by reducing the contact force created between the tab contact and the outer contact members, which clean the upper and lower surfaces of the tab contact. In this manner, the initial insertion force of the tab contact within the outer contact members is less than the insertion force of the inner contact members.

In accordance with the invention, an electrical receptacle apparatus includes at least one electrical receptacle adapted to conductively engage a blade terminal or the like. The electrical receptacle includes upper means extending forwardly, and having a lower surface with at least first, second and third upper contact locations formed thereon. Lower means are provided which extend forwardly and are conductively interconnected to and positioned substantially directly below the upper means. The lower means include an upper surface with at least first, second and third lower contact locations formed thereon. The receptacle is sized and configured so that the blade terminal is insertable between the upper means and the lower means, and is adapted to conductively contact the receptacle at the first, second and third upper and lower contact locations. In this manner, at least six conductive electrical contact locations are formed with the receptacle.

The first, second and third upper contact locations can be formed substantially within a single upper plane, and form a triangular configuration within the upper plane. Correspondingly, the first, second and third lower contact locations can be formed substantially within a single lower plane, and form a triangular configuration with the lower plane. Each of the first, second and third lower contact locations can be respectively positioned substantially directly below each of the first, second and third upper contact locations.

The upper means can include at least one pair of upper lateral arms extending forwardly. The upper means can also include an upper bridge portion positioned transversely across forward portions of the upper lateral arms. The upper bridge portion and the upper lateral arms form an upper spatial area. Upper cantilever means are positioned substantially within the upper spatial area, and comprise an arcuate shape forming the first upper contact location thereon. Correspondingly, the second and third upper contact locations can be formed at interconnections of the upper bridge portion and the upper lateral arms.

The lower surface of the upper means is formed of a lower surface of the upper cantilever means and lower surfaces of the upper bridge portion and upper lateral arms. The upper cantilever means is conductively interconnected to the upper lateral arms.

The lower means can include at least one pair of lower lateral arms extending forwardly. A lower bridge portion can be positioned transversely across forward portions of the lower lateral arms, and conductively interconnect the lower lateral arms. The lower bridge portion and lower lateral arms form a lower spatial area. Lower cantilever means are provided which are positioned substantially within the lower spatial area, and comprise an arcuate shape forming the first lower contact location thereon. Correspondingly, the second and third lower contact locations are formed at interconnections of the lower bridge portion and lower lateral arms.

The upper surface of the lower means is formed of an upper surface of the lower cantilever means and upper surfaces of the lower bridge portion and the lower lateral arms. The lower cantilever means is conductively interconnected to the lower lateral arms.

In accordance with another aspect of the invention, the receptacle apparatus can comprise four of the electrical receptacles. The apparatus can further comprise a connecting beam central to and symmetrically located relative to the four receptacles. The connecting beam can be rectangular in configuration and integrally connected to each of a pair of secondary connecting portions through a pair of U-shaped connecting portions formed at ends of the connecting beam. Each of the secondary connecting portions can form an integral support portion for the upper means.

The apparatus can further comprise a common terminal input channel conductively interconnected to the receptacles. A pair of crimp wings can be formed at lateral sides thereof.

The upper means can include a pair of upper substantially parallel and elongated lateral arms extending forwardly. An upper bridge portion can be conductively interconnected to the upper lateral arms. The upper bridge portion and the upper lateral arms form an upper spatial area. An upper cantilever member can extend forwardly within the upper spatial area, and comprise an arcuate shape forming a first upper contact location on a lower surface thereof. The upper bridge portion can be angled upwardly in a forward direction, and the upper lateral arms can be angled downwardly in a forward direction. The intersections of the upper bridge portion and upper lateral arms form the second and third upper contact locations. The upper cantilever member can be resilient in structure and comprise a rear downwardly angled portion integrally connected at a forward portion thereof to a forward upwardly angled portion. The first upper contact location can be formed at an interface of the rear downwardly angled portion and the forward upwardly angled portion.

An illustrative embodiment of the invention will now be described with respect to the drawings, in which:

FIG. 1 is a perspective view of an electrical contact arrangement in accordance with the invention;

FIG. 2 is a top plan view of the contact arrangement shown in FIG. 1;

FIG. 3 is a side view of the contact arrangement shown in FIG. 1;

FIG. 4 is an end view of the contact arrangement shown in FIG. 1;

FIG. 5 is an underside view from the opposing side of the contact arrangement shown in FIG. 2;

FIG. 6 is a sectional view of the contact arrangement, taken along section lines 6--6 of FIG. 2;

FIG. 7 is a side view showing an example insertion arrangement of a blade terminal into the contact arrangement;

FIG. 8 is an illustration similar to FIG. 7, showing further insertion of the blade terminal; and

FIG. 9 is an illustration similar to FIG. 8, showing final position insertion of the blade terminal.

The principles of the invention will now be disclosed, by way of example, in an electrical contact unit 100 as illustrated in FIGS. 1-9. Although the electrical contact unit 100 described in subsequent paragraphs herein includes a series of four electrical receptacles, the principles of the invention are not limited, in any manner, to the use of four such receptacles. For example, the principles of the invention can be included within one electrical receptacle or any other desired number. The contact unit 100 as described herein provides at least six locations of contact with respect to the electrical engagement of male blade terminals with the electrical contact unit. In addition, the contact unit 100 in accordance with the invention also provides a preferable triangular positioning of contact points so as to maintain a stable electrical connection between the blade terminals and the elements of the electrical receptacles.

Referring primarily to FIG. 1, the electrical contact unit 100 includes a series of four electrical receptacles 102, 104, 106 and 108. As illustrated in FIGS. 1-6, each electrical receptacle 102, 104, 106 and 108 includes an outer, elongated and upper cantilever member 110, and an opposing lower cantilever member 112. The upper cantilever members 110 each include a pair of lateral and parallel elongated arms 114 integrally connected at their forward ends by a bridge portion 116. Correspondingly, each of the lower cantilever members 112 includes corresponding lateral arms 118 integrally connected at their forward ends by a lower bridge portion 120.

As illustrated primarily in FIGS. 3 and 6, the upper lateral arms 114 have a slight downwardly angled configuration, while the upper bridge portion 116 is angled slightly upwardly. With this configuration, a contact surface or edge 122 is formed at the integral interface between the upper bridge portion 116 and each of the lateral arms 114. Correspondingly, the lateral arms 118 of the lower cantilever members 112, as further illustrated in FIGS. 3 and 6, are angled slightly upwardly, while the lower bridge portion 120 is angled slightly downwardly. With this configuration, a contact surface or edge 124 is provided at the interface between the integrally connected lateral arms 118 and lower bridge portion 120.

As shown primarily in FIGS. 2 and 5, the lateral arms 110 and bridge portion 116 of the upper cantilever members 110 form an arcuate spatial area 126 internal to the arms 114 in bridge portion 116. A similar spatial area 127 is formed by the lateral arms 118 and lower bridge portion 120 of the lower cantilever members 112. With respect specifically to FIG. 2, each of the receptacles 102, 104, 106 and 108 also includes an inner and upper cantilever member 128 which extends forwardly within the spatial area 126 formed by the lateral arms 114 and bridge portion 116. An opposing inner cantilever member 130 is formed within the corresponding spatial area 127 of the lower cantilever members 112 and also extends forwardly. As illustrated primarily in FIGS. 3 and 6, each of the upper cantilever members 128 is resilient in structure and has a rear downwardly angled portion 132 integrally connected at the forward portion thereof to a forward upwardly angled portion 134. Correspondingly, each of the lower and inner cantilever members 130 includes a rear upwardly angled portion 136 integrally connected at its forward end to a forward downwardly angled portion 138. The interface between the rear downwardly angled portion 132 and forward upwardly angled portion 134 of the upper cantilever member 128 forms a contact surface or edge 140. Correspondingly, a contact surface or edge 142 is formed at the interface between the integrally connected rear upwardly angled portion 136 and forward downwardly angled portion 138 of the lower cantilever members 130.

The opposing upper and lower cantilever members 110, 112 and the opposing inner cantilever members 128, 130 are flexible and resilient in nature so as to be appropriately flexed when a male blade terminal (illustrated in FIGS. 7-9) is inserted between the opposing cantilever members. In addition, as will be further apparent from additional description herein, the contact surfaces 122 and 140 associated with the upper cantilever member 110 and the upper cantilever member 128 form a triangular contact surface configuration with the male blade terminal. Correspondingly, the contact surfaces 124 and 142 form an opposing triangular contact surface configuration, thereby providing six points of contact between the electrical receptacles 102, 104, 106 and 108 and the inserted male blade terminal. This triangular configuration provides a substantial stabilizing effect to the interconnection between the male blade terminal and the electrical receptacles, while correspondingly providing six points of contact.

Referring again primarily to FIGS. 1, 2 and 5, the four-receptacle unit 100 includes a connecting beam 144 central to and symmetrically located relative to the receptacles 102, 104, 106 and 108. The connecting beam 144 is rectangular in configuration and is integrally connected to each of two secondary connecting portions 146 by means of a U-shaped connecting portion 148 formed at each of the ends of the connecting beam 144. Each of the secondary connecting portions 146 also forms an integral inner support portion for the upper cantilever members 110 and the upper cantilever members 128.

As further illustrated in FIGS. 1, 2 and 5, the four-receptacle unit 100 includes a common terminal input channel 150 having a pair of crimp wings 152 integrally formed at the lateral sides of the channel 150. The channel 150 includes a transition portion 154 integrally connecting the common terminal input channel 150 with the connecting beam 144. In addition to the foregoing, the receptacle unit 100 also includes a pair of tabs 156 each formed on one side of each of the secondary connecting portions 146. These tabs 156 provide a means for controlling positioning of the "boxes" formed by the surfaces of the connecting beam 144, secondary connecting portions 146 and U-shaped connecting portions 148.

The use of the electrical contact unit 100 with corresponding insertion of a male blade terminal 158 will now be described with respect to FIGS. 7-9. The male blade terminal or tab contact 158 may, as illustrated in FIGS. 7, 8 and 9, include tapered surfaces at its forward portion for purposes of facilitating insertion into the electrical receptacles 102, 104, 106 and 108. For purposes of illustration, FIGS. 7, 8 and 9 only illustrate one of the electrical receptacles 106. The forward portion of the blade terminal 158 is first inserted into the spatial area formed between the upper bridge portion 116 and lower bridge portion 120. As the blade terminal 158 is inserted, upper and lower surfaces of the terminal 158 will contact the upper contact surfaces 122 and lower contact surfaces 124 formed at the interface between the bridge portions 116, 120 and the lateral arms 114, 118. As the blade terminal 158 is further inserted, the forward portion of the terminal 158, at its upper and lower surfaces near the central portions thereof, will engage in an electrical contact with the contact surfaces 140, 142 formed at the interfaces of the integrally connected downwardly angled portion 132 and forwardly and upwardly angled portion 134 of the upper cantilever member 128, and the interface between the integrally connected upwardly angled portion 136 and downwardly angled portion 138

As previously described, the upper contact surfaces 122 and 140 provide a triangular configuration, with three locations of electrical contact. This triangular configuration provides a substantial stabilizing effect which prevents relatively poor contact if the interconnection between the male blade terminal 158 and the corresponding receptacle is jarred or otherwise subjected to a "rocking" movement. Correspondingly, the three locations of lower contact provided by the contact surfaces 124 and 142 provide a corresponding triangular contact surface configuration opposing the upper contact configuration. With the three points of lower contact, the interconnection and engagement between the male blade terminal 158 and the corresponding electrical receptacle is provided with six locations of contact. Still further, if the male blade terminal 158 is appropriately sized relative to the relative positioning of the bridge portions 116, 120, the surfaces of the bridge portions 116, 120 will provide a "wiping" engagement with the central portion of the upper and lower surfaces of the blade terminal 158. This wiping engagement will ensure that the central portion of the blade terminal 158 which will be in electrical contact with the upper and inner cantilever member 128 and lower and inner cantilever member 130 will be free from any foreign matter as a result of the "cleaning" function carried out by the bridge portions 116, 118. With the six locations of contact provided for each of the electrical receptacles 102, 104, 106 and 108, the electrical current-carrying capability of the receptacles is greatly improved. In addition, with respect to the particular four-receptacle unit 100 illustrated herein, four receptacles are provided with the necessity of only a single wire crimp configuration in an integral terminal, thereby providing an efficient use of space within a connector system. Still further, the triangular positioning of the three locations of contact on each of the upper and lower surfaces of the male blade terminal provide a substantially "steady" platform for the male blade terminal 158.

As apparent from the foregoing, the electrical connector unit 100 can be formed from a suitable metal sheet by means of stamping and forming the unit 100, with the sheet having the appropriate conductive and spring and resiliency characteristics. Such a stamping process can be achieved by utilizing a suitably formed metal sheet, and then folding over the elements forming the upper cantilever members 110 and the secondary connecting portions 146.

It will be apparent to those skilled in the pertinent arts that other embodiments of electrical contact units in accordance with the invention can be achieved. That is, the principles of an electrical contact unit in accordance with the invention are not limited to the specific embodiment described herein. For example, an electrical contact unit in accordance with the invention can employ other than four electrical receptacles. It will be apparent to those skilled in the art that modifications and other variations of the above-described illustrative embodiment of the invention may be effected without departing from the spirit and scope of the novel concepts of the invention.