Electric connector

0001The present invention relates to an electric connector used mainly for high-speed digital signaling and capable of providing good impedance matches.

0002In a known electric connector of this type, an insulative body has groups of contacts disposed in two rows along its width, and the groups of contacts are arranged in a staggered or zigzag manner. The groups of contacts include ground contacts and pairs of signal contacts to serve as differential pairs for high-speed digital signaling.

0003Some of the ground contacts are wider than some of the signal contacts making up a pair, and each of the ground contacts is arranged so that their widthwise ends overlap widthwise ends of each pair of signal contacts in plain positions. With this structure, impedance is matched within each differential pair of contacts and among the differential pairs of contacts (see Japanese Published Patent Publication No.<patcit id="pcit0001" dnum="JP2003505826A"><text> 2003-505826</text></patcit> (Translation of Published International Application No. <patcit id="pcit0002" dnum="WO01006602A"><text>WO01/006602</text></patcit>)).

0004However, as to a differential pair located at an outermost end of the groups of contacts, there is no ground contact disposed at one side of a signal contact of the differential pair. Therefore, capacitance of this signal contact with respect to a ground contact is smaller as compared with that of the other signal contact of the same differential pair, with the result of increased impedance. For this reason, there are impedance mismatches between the contacts, thereby degrading transmission characteristics of the connector.

0005In this case, it is not impossible to improve impedance matching by disposing a dummy ground contact at the side of the signal contact in question or by bringing a portion of a shield cover of the electric connector close to the signal contact. However, the addition of a dummy ground contact or the change in shape of the shield cover will cause increase in the number of components and assembly steps, leading to increased costs.

0006The present invention was made in view of the above circumstances, and an embodiment of the present invention provides an electric connector capable of providing good impedance matches without adding a dummy ground contact or changing the shape of the shield cover.

0007In order to overcome the above problems, an electric connector according to the present invention includes an insulative body; and groups of contacts disposed in spaced relationship inside the body, the contacts being arranged in at least two rows in a lateral direction of the body. The groups of contacts include a plurality of first contacts; and a plurality of second contacts located in a different row from a row where their associated first contacts exist, the second contacts being arranged next to the first contacts. Out of one of the first contacts and one of the second contacts subject to impedance tuning, one of these two contacts has a width and an area thereof adjusted to compensate for any difference in impedance relative to impedances between other first and second contacts.

0008With such an electric connector, since one of the two contacts subject to impedance tuning has a width and an area thereof adjusted in accordance with a difference in impedance from impedances between other first and second contacts, impedance can be matched between the first and second contacts without adding a dummy ground contact or changing the shape of the shield cover; therefore, transmission characteristics of the connector can be improved without increase in costs.

0009The first and second contacts subject to impedance tuning may be first and second contacts at an outermost end in the groups of contacts in the lateral direction of the body. In this case, one of the first and second contacts present at the outermost end has its width and area adjusted to compensate for any difference in impedance from impedances between other first and second contacts.

0010The groups of contacts may be arranged such that a plurality of sets is disposed in the lateral direction of the body with respective vertical positional relationships of the sets turned upside down alternately. Each of the sets may be made up by a pair of first contacts and a second contact, and the first contacts may be signal contacts and the second contact may be a ground contact. In this case, the pair of first contacts opposes the second contact within each set, while the pair of first contacts is positioned next to second contacts from other sets. This contact arrangement is advantageous in terms of impedance matching and reduction in crosstalk within each pair of first contacts.

0011It is preferred that in each of the sets, widthwise ends of the second contact are so positioned as to overlap widthwise inner ends of the pair of first contacts in plain position. That is to say, when viewed from below, and disregarding the material of the projecting portion of the connector body positioned between the upper and lower groups of contacts, the widthwise ends or edges of the lower contact overlap or overlie the widthwise inner ends of edges of the upper contact in each set. Conversely, when viewed from above, the upper contacts overlap or overlie the lower contacts at the edges. This arrangement is advantageous in terms of impedance matching within each pair of first contacts.

0012Preferably, an overlapping width and area N1 is larger than an overlapping width and area N2, wherein N1 is an overlapping width and area where an outer end of a second contact at an outermost widthwise end of the groups of contacts overlaps, in plain position, a first contact at the outermost end, and N2 is an overlapping width and area where an outer end of another second contact overlaps, in plain position, an inner end of another first contact.

0013In this case also, impedance can be matched within the pair of first contacts at the outermost end without adding a dummy ground contact or changing the shape of the shield cover.

0014The electric connector may be configured such that the first contacts each include a first main portion to be held in the body, a first contact portion continuous from or integral with a distal end of the first main portion and exposed from a first end in a longitudinal direction of the body, a first lead-out portion continuous from or integral with a rear end of the first main portion and exposed from a second end in the longitudinal direction of the body, and a first lead portion continuous from or integral with a rear end of the first lead-out portion, while the second contacts each include a second main portion to be held in the body, a widthwise end of the second main portion being located in such a plain position as to overlap a widthwise end of the first main portion of the nearest first contact, a second contact portion continuous from or integral with a distal end of the second main portion and exposed from the first end in a longitudinal direction of the body, a second lead-out portion continuous from or integral with a rear end of the second main portion and exposed from the second end in the longitudinal direction of the body, and a second lead portion continuous from or integral with a rear end of the second lead-out portion. In this case, an overlapping width and area N1 is preferably larger than an overlapping width and area N2, wherein N1 is an overlapping width and area where an outer end of a second main portion of a second contact at an outermost widthwise end of the groups of contacts overlaps, in plain position, a first main portion of a first contact at the outermost end, and N2 is an overlapping width and area where an outer end of a second main portion of another second contact overlaps, in plain position, an inner end of a first main portion of another first contact.

0015An electric connector according to an embodiment of the present invention will now be described below by way of example only with reference to the drawings, in which: <ul id="ul0001" list-style="none" compact="compact"><li><figref idref="f0001">FIG. 1</figref> is a schematic front view of an electric connector according to an embodiment of the present invention;</li><li><figref idref="f0002">FIG. 2</figref> is a schematic plan view of the electric connector;</li><li><figref idref="f0003">FIGS. 3A and 3B</figref> are schematic back views of the electric connector, where <figref idref="f0003">FIG. 3A</figref> shows a state in which a shield cover is closed, whereas <figref idref="f0003">FIG. 3B</figref> shows a state in which the shield cover is opened;</li><li><figref idref="f0004">FIG. 4</figref> is a schematic plan view of a body of the electric connector, with groups of contacts attached thereto;</li><li><figref idref="f0005">FIG. 5</figref> is a schematic cross-sectional view of the body of the electric connector, with the groups of contacts attached thereto;</li><li><figref idref="f0006">FIGS. 6A and 6B</figref> show arrangement of contacts of the electric connector, where <figref idref="f0006">FIG. 6A</figref> is a schematic plan view and <figref idref="f0006">FIG. 6B</figref> is a schematic bottom view; and</li><li><figref idref="f0007">FIG. 7A</figref> is a schematic perspective view of a first or a second contact of the electric connector, and <figref idref="f0007">FIG. 7B</figref> is a schematic perspective view of a second contact at an outermost end of the electric connector.</li></ul>

0016In the description which follows, relative spatial terms such as "upper", "lower", "downward", "under", "bottom", etc., are used for the convenience of the skilled reader and refer to the orientation of the connector or contacts and their constituent parts as depicted in the drawings. No limitation is intended by use of these terms, either in use of the invention, during its manufacture, shipment, custody, or sale, or during assembly of its constituent parts or when incorporated into or combined with other apparatus.

0017The electric connector shown in <figref idref="f0001 f0002 f0003">FIGS. 1 to 3</figref> is a receptacle adapted to be mounted to a circuit board, capable of high-speed differential signaling. The electric connector includes an insulative body 100, upper and lower groups of contacts 200a and 200b, and a shield cover 300 covering the outer periphery of the body 100. The upper and lower groups of contacts 200a and 200b are disposed in spaced relationship inside the body and arranged in two rows in a lateral direction of the body 100 in a staggered or zigzag manner. Each of the components of the electric connector is detailed in the following description.

0018In the drawings and in the following paragraphs, first or upper contacts and their features have an "a" suffix, and second or lower contacts and their features have a "b" suffix. Similarly, sets of first (upper) and second (lower) terminal insertion holes provided in the electrical connector are denoted by 111a and 111b, respectively.

0019As shown in <figref idref="f0001">FIGS. 1</figref>, <figref idref="f0003">3A</figref>, <figref idref="f0003">3B</figref>, <figref idref="f0004">4</figref> and <figref idref="f0005">5</figref>, the body 100 is formed from a synthetic resin for general use such as PBT (polybutylene terephthalate) or PPS (polyphenylene sulfide) by injection molding. The body 100 can be mated with a plug A, shown in dotted outine in <figref idref="f0005">FIG. 5</figref>.

0020The body 100 includes a connector main portion 110 having a substantially rectangular solid shape, a projecting portion 120 having a substantially inverted-U shape as viewed from the front, a base 130 having a substantially plate-like shape, and a cylindrical boss 140. The projecting portion 120 is provided at the front side of the connector main portion 110 and adapted to enter into a recess provided at a tip end of the plug A. The base 130 is provided under the connector main portion 110 and extended forward. The boss 140 is formed downward on a bottom surface of the base 130 and fits into a hole (not shown) in the circuit board.

0021In a central portion of the connector main portion 110 of the body 100, terminal insertion holes 111a and 111b are lined at equal pitch intervals in the lateral direction of the electric connector in two rows. These holes in two rows are shifted in phase from one another with spacing in between, so as to correspond to contacts (not shown) of the plug A. As shown in <figref idref="f0001">FIG. 1</figref>, the widthwise ends of the first terminal insertion holes 111a are located in such plan positions as to overlap the widthwise ends of the second terminal insertion holes 111b.

0022The terminal insertion holes 111a and 111b are through holes of horizontally elongated rectangular shape. Ten such holes are provided in each of the upper and lower rows to correspond to contact main portions 2012a and 2022b of the upper and lower groups of contacts 200a and 200b. Of the twenty terminal insertion holes, all holes other than a terminal insertion hole 111b' at the rightmost end in the lower row in <figref idref="f0001">FIG. 1</figref> are identical to one another. The terminal insertion hole 111b' at the rightmost end is a through hole of a horizontally elongated rectangular shape, is wider than the other terminal insertion holes 111a and 111b, and corresponds to a main portion 2012b in the lower group of contacts 200b. Regarding the terminal insertion hole 111b' at the rightmost end, an apostrophe is added to the reference numeral as above for distinction from the other terminal insertion holes 111b.

0023As shown in <figref idref="f0003">FIGS. 3B</figref> and <figref idref="f0005">5</figref>, a cutout 112 is provided in the rear surface of the connector main portion 110. In the inner back surface of the cutout 112, there are linear terminal insertion grooves 113 extending downward under the respective terminal insertion holes 111a and 111b. The terminal insertion grooves 113 are long grooves arranged in the lateral direction of the body. The terminal insertion grooves 113 correspond in lateral width to lead-out portions 2013a and 2013b of the upper and lower groups of contacts 200a and 200b.

0024As shown in <figref idref="f0001">FIG. 1</figref>, in an upper surface of the projecting portion 120 of the body 100, there are provided terminal guide grooves 121a communicating with the terminal insertion holes 111a in the connector main portion 110 and extending in straight lines in a longitudinal direction of the body 100. In the lower surface of the projecting portion 120, there are provided terminal guide grooves 121b communicating with the terminal insertion holes 111b in the main portion 110 and extending in straight lines in a longitudinal direction of the body 100. The terminal guide grooves 121a and 121b correspond in lateral width to contact portions 2011a and 2011b of the upper and lower groups of contacts 200a and 200b. The terminal guide grooves 121a and 121b are shifted from each other in phase in the lateral direction, in a similar manner to the terminal insertion holes 111a and 111b.

0025The shield cover 300, as shown in <figref idref="f0001 f0002 f0003">FIGS. 1 to 3B</figref>, is a metal shell which can be brought into contact with an outer peripheral shield (not shown) of the plug A as mated with the body 100. The shield cover 300 includes a cover main body 310, a pair of legs 320 extending downward from opposite widthwise ends of the cover body 310, and a back cover 330 for openably covering an opening on the back side of the cover body 310.

0026The cover body 310, shaped as a substantially square cylinder, fits about the connector main portion 110 of the body 100 so as to cover four sides - upper, lower, right and left sides - of the connector main portion 110 and the projecting portion 120 (i.e., the outer peripheries of the connector main portion 110 and the projecting portion 120).

0027The legs 320 are adapted to be inserted into attachment holes (not shown) in the circuit board and connected to a ground pattern on the circuit board.

0028The back cover 330 is a plate-like member that has its upper end pivotably attached to an upper edge of the opening on the rear side of the cover main body 310. The back cover 330 closes the opening on the rear side of the cover main body 310 so as to cover the rear side of the connector main portion 110 of the body 100.

0029As shown in <figref idref="f0006">FIGS. 6A and 6B</figref>, the upper contact group 200a consists of contacts 201a-210a. The lower contact group 200b consists of contacts 201b-210b.

0030As shown in <figref idref="f0006 f0007">FIGS. 6A to 7B</figref>, the contact 201a is representative of the contacts in the upper contact group 200a and includes a contact portion 2011a, a contact main portion 2012a, a lead-out portion 2013a, and a lead portion 2014a. The contact portion 2011a is a plate-like portion that can be brought into contact with a contact (not shown) of the plug A as engaged with the projecting portion 120 of the body 100. The contact main portion 2012a, a plate-like portion with a larger width than that of the contact portion 2011a, is provided continuously from or integral with the rear end of the contact portion 2011a and is adapted to be press fitted into the associated terminal insertion hole 111a in the body 100. The lead-out portion 2013a, a rod-like portion provided continuously from or integral with the rear end of the contact main portion 2012a, is bent substantially at a right angle so as to extend along the rear surface of the body 100. The lead portion 2014a, a rod-like portion provided continuously from or integral with the rear end of the lead-out portion 2013a, is bent substantially at a right angle so as to be connected to a pattern on the circuit board.

0031The contact 202b is one of the contacts in the lower contact group 200b and includes a contact portion 2021b, a contact main portion 2022b, a lead-out portion 2023b, and a lead portion 2024b. The contact portion 2021b is a plate-like portion which can be brought into contact with a contact (not shown) of the plug A as engaged with the projecting portion 120 of the body 100. The contact main portion 2022b, a plate-like portion with a larger width than that of the contact portion 2021b, is provided continuously from or integral with the rear end of the contact portion 2021b and is adapted to be press fitted into the associated terminal insertion hole 111b in the body 100. The lead-out portion 2023b, a rod-like portion provided continuously from or integral with the rear end of the contact main portion 2022b, is bent substantially at a right angle so as to extend along the rear surface of the body 100. The lead portion 2024b, a rod-like portion provided continuously from or integral with the rear end of the lead-out portion 2023b, is bent substantially at a right angle so as to be connected to the pattern on the circuit board.

0032As shown in <figref idref="f0003">FIG. 3B</figref>, the contacts of the upper group 200a such as contact 201a and the contacts of the lower group 200b such as contact 202b are different from each other in that the lead-out portion 2013a is longer than the respective lead-out portion 2023b by the length of distance between the upper row and the lower row. Contacts 202a, 204a, 205a, 208a and 209a are the same as the contact 201a.

0033As shown in <figref idref="f0006">FIG. 6A</figref>, contacts 203a, 206a, 207a and 210a are the same as the contact 201a except that their contact portions 2031a, 2061a, 2071a and 2101a are each longer than the contact portion 2011a of the contact 201a.

0034Contacts 203b, 205b, 206b and 209b are the same as the contact 202b. Contacts 204b, 207b, 208b and 210b are the same as the contact 202b except that their contact portions 2041b, 2071b, 2081b and 2101b are each longer than the contact portion 2021b of the contact 202b.

0035As shown in <figref idref="f0006">FIG. 6B</figref>, a contact 201b is the same as the contact 202b, except that its contact portion 2011b is longer than the contact portion 2021b of the contact 202b and that it has a plate-like extended portion 2012b1 along a widthwise end of the main portion 2012b.

0036The electric connector according to the present embodiment is used as a power source line and also used for transmission of single end signals and first to fifth differential signals. The contacts 207a, 210a, 207b, 209b and 210b are connected to a pattern on the circuit board to function as contacts used in a power supply line or for single-ended signaling. On the other hand, as connected to the pattern on the circuit board, the contacts 201a, 202b, 204a, 205b and 208a function as positive signal contacts (i.e., one of first contacts in each pair) for transmission of the first to fifth differential signals, the contacts 202a, 203b, 205a, 206b and 209a function as negative signal contacts (i.e., the other one of the first contacts in each pair) for transmission of the first to fifth differential signals, and the contacts 201b, 203a, 204b, 206a, and 208b function as common ground contacts (i.e., second contacts) for transmission of the first to fifth differential signals, respectively.

0037Among the upper and lower groups of contacts 200a and 200b, of special note are the contacts 201a-206a, 208a, 209a, 201b-206b and 208b for transmission of the first to fifth differential signals. As shown in <figref idref="f0001">FIG. 1</figref>, these contacts are disposed in five sets of triangular arrangements on a cross sectional plain of the body 100: each triangular set or group of three contacts is formed by one positive signal contact and one negative signal contact disposed at one side of the triangular arrangement and one common ground contact disposed at the opposite apex. These five sets are sequentially arranged in the lateral direction of the body 100 with their vertical orientations alternately inverted.

0038In the electric connector in the present embodiment, the contacts for signal transmission and other use are arranged in the above-described relationship. Therefore, for the purpose of reducing a skew, etc. between adjacent contacts of each differential pair and between the differential pairs, the longitudinal relationship among the contact portions 2011a-2111a of the contacts 201a-210a and the contact portions 2011b-2111b of the contacts 201b-210b is established as shown in <figref idref="f0006">FIGS. 6A and 6B</figref>.

0039The contacts 201a-210a are positioned and inserted into ten associated terminal insertion holes 111a in the body 100 from the rear side of the body 100. Then, the contact portions 2011a-2101a of the contacts 201a-210a are received in the respective ten terminal guide grooves 121a in the body 100. Simultaneously therewith, the contact main portions 2012a-2102a of the contacts 201a-210a are press fitted within the respective ten terminal insertion holes 111a, and the lead-out portions 2013a-2103a are received in the respective ten terminal insertion grooves 113.

0040Meanwhile, the contacts 201b-210b are positioned and inserted into the terminal insertion hole 111b' and the nine terminal insertion holes 111b in the body 100, respectively, from the rear side of the body 100. Then, the contact portions 2011b-2101b of the contacts 201b-210b are received in the respective ten terminal guide grooves 121b in the body 100. Simultaneously therewith, the contact main portions 2012b-2102b of the contacts 201b-210b are press fitted within the terminal insertion hole 111b' and the nine terminal insertion holes 111b, respectively, and the lead-out portions 2013b to 2103b are received in the remaining ten terminal insertion grooves 113.

0041As shown in <figref idref="f0006">FIGS. 6A and 6B</figref>, in the upper contact group 200a and the lower contact group 200b as fixed to the body 100 in the above-described manner, the widthwise ends of the contact main portions 2012a-2102a of the contacts 201a-210a are located in such plain positions as to overlap the widthwise ends of the contact main portions 2012b-2102b of the contacts 201b-210b.

0042As a consequence, in any one of the common ground contacts, opposite widthwise ends of the contact main portion are located in such plain positions as to overlap an inner widthwise end of the contact main portion of the adjacent plus signal contact and an inner widthwise end of the contact main portion of the minus signal contact. In addition, adjacent to these plus signal contacts and minus signal contacts, the common ground contacts in other sets are arranged. This arrangement of the contacts achieves excellently matched impedances in the respective differential pairs of contacts.

0043The overlapping width and area (N1) of the extended portion 2012b1 of the contact main portion 2012b of the contact 201b overlapping the contact main portion 2012a of the contact 201a is approximately twice as large as each overlapping width and area (N2) of the ends of contact main portions of any other two contacts for differential signaling (i.e., the outer end and the inner end in each triangular set-for example, an end of the contact main portion 2032a of the contact 203a and an end of the contact main portion 2022b of the contact 202b that are next to each other). In this manner, adjustment is made to the width and area of the contact main portion 2012b of the contact 201b, in accordance with the difference in impedance from other signal contacts with respect to common ground contacts. This structure prevents reduction in capacitance between the contact 201a and the contact 201b that should have been created due to the location of the contact 201a at the outmost end of the upper group of contacts 200a and absence of a neighboring common ground contact. Consequently, it becomes possible to suppress variation in impedance within the differential pair located at the outmost end of the groups of contacts, providing matched impedances.

0044With the electric connector as described above, impedance can be matched within the differential pair at an outmost end of the groups of contacts without adding a dummy ground contact or changing the shape of the shield cover 300 as has been previously described. Matched impedances within each pair should result in matched impedances among the differential pairs. Accordingly, the transmission characteristics of the electric connector can be improved without increase in costs.

0045It should be noted that any change in design can be made to the above-described electric connector as long as it includes an insulative body and groups of contacts disposed in spaced relationship inside the body, the contacts being arranged in at least two rows in a lateral direction of the body, as long as the groups of contacts include a plurality of first contacts; and a plurality of second contacts located in a different row from a row where their associated first contacts exist, the second contacts being arranged next to the first contacts, and as long as, out of one of the first contacts and one of the second contacts subject to impedance tuning, one of these two contacts has a width and an area thereof adjusted in accordance with a difference in impedance from impedances between other first and second contacts.

0046Although it is described in the above-described embodiment that adjustment is made to the width and area of the common ground contact located at an outermost end in the groups of contacts, the present invention is not limited thereto. For instance, the width and area of the main portion 2012a of the contact 201a, which is a signal contact, may be reduced as compared with other signal contacts, thereby preventing reduction in capacitance between the contacts 201a and 201b to match the impedances.

0047Further, although it is described in the above-described embodiment that the contacts subject to impedance tuning are the contacts 201a, 202a, and 201b that are the differential pair and the common ground contact thereof at the outermost end in the groups of contacts, the present invention is not limited thereto. That is, contacts subject to impedance tuning may be appropriately selected depending on the arrangement of the contacts.

0048The present electric connector can be applied to an electric connector for unbalanced (single-ended) signaling. More particularly, adjustment may be made to a single-ended signal contact and a ground contact thereof subject to impedance tuning, by adjusting a width and area of one of these two contacts in accordance with the difference in impedance from another set of a single-ended signal contact and a ground contact.

0049The geometry of the contacts is not limited to one described in the above-described embodiment, and any change in design can be made.

0050The arrangement design of the contacts can be changed as appropriate, so long as the contacts are arranged with spacing in at least two rows in the lateral direction inside the body. In the case where the present electric connector is an electric connector for differential signaling, it is preferable that, with a positive signal contact, a negative signal contact, and a common ground contact constituting a set in a triangular arrangement as described above, a plurality of such sets is arranged one set after another in the lateral direction; however, the present invention is not limited thereto. The contact arrangement may be modified such that, for example, a plurality of positive and negative signal contacts is arranged in a first row, and a plurality of common ground contacts is arranged in a second row. The contacts can also be arranged such that their widthwise ends do not overlap one another in their plain positions.

0051In addition, although the above electric connector is described as a receptacle, it may alternatively be a plug having contacts connected to a cable.

Component List

0052<dl id="dl0001"><dt>100</dt><dd>BODY</dd><dt>200a</dt><dd>UPPER GROUP OF CONTACTS</dd><dt>201a</dt><dd>CONTACT (ONE OF FIRST CONTACTS) 2011a CONTACT PORTION 2012a MAIN PORTION 2013a LEAD-OUT PORTION 2014a LEAD PORTION</dd><dt>202a</dt><dd>CONTACT (THE OTHER OF FIRST CONTACTS) 2021a CONTACT PORTION 2022a MAIN PORTION 2023a LEAD-OUT PORTION 2024a LEAD PORTION</dd><dt>200b</dt><dd>LOWER GROUP OF CONTACTS</dd><dt>202b</dt><dd>CONTACT (SECOND)</dd><dt>2011b</dt><dd>CONTACT PORTION</dd><dt>2012b</dt><dd>MAIN PORTION 2012b1 EXTENDED PORTION</dd><dt>2013b</dt><dd>LEAD-OUT PORTION</dd><dt>2014b</dt><dd>LEAD PORTION</dd></dl>