1. Field of the Invention
The present invention relates to a multipolar electrical connector which is to be disposed on a memory card such as an IC card, in order to connect various devices mounted on the memory card with electronic circuits of a computer system.
2. Description of the Prior Art
Such a multipolar electrical connector for a memory card (hereinafter, referred to as merely "connector") is attached to the front end portion of the body of the memory card so as to be united with the body of the memory card. The connector has an electrically insulating body wherein a number of pin terminal insertion spaces into which pin terminals of a counter multipolar electrical connector (hereinafter, referred to as merely "counter connector") are to be respectively inserted are formed. In each of the pin terminal insertion spaces, a contact piece which functions as a contact and which corresponds to a pin terminal of the counter connector is housed.
Conventionally, connectors having such a configuration, are known, such as those shown in FIGS. 7 to 10. These have a number of contacts (number of contacting points) for pin terminals of a counter connector, and a positional relationship in the front-to-back direction between a contact with which a pin terminal of a counter connector contacts and the rocking fulcrum of a contact piece.
The connector shown in FIG. 7 comprises an insulating body A in which pin terminal insertion spaces B are formed. In each of the pin terminal insertion spaces B, a pair of plate-like elongated contact pieces C, C which extend in the pin terminal insertion and extraction direction X are symmetrically arranged. The contact pieces C, C are electrically connected with each other by a short-circuit portion D made of a thin metal plate. The short-circuit portion D and the paired contact pieces C, C are formed into one body by punching or bending a thin metal plate which is common to them.
The connector of FIG. 8 comprises a pair of contact pieces C, C and a short-circuit portion D which also are formed by punching a thin metal plate. The edge faces (which are formed as a result of a punching process of the thin metal plate) of the contact pieces C, C function as contacts F, F.
In the connector of FIG. 9, contacts F, F of paired contact pieces C, C are positionally shifted in the front-to-back direction, and the base portions of the contact pieces C, C are electrically connected with each other by a short-circuit portion D.
In the pair of contact pieces C, C used in the connectors of FIGS. 7, 8 and 9, the contacts F, F corresponding to a pin terminal G1 or G2 are at positions (given positions in the pin terminal extraction direction X1) which are located more forward than rocking fulcrums E, E respectively located in the base portions.
The connector shown in FIG. 10 is similar to that of FIG. 7 in that a pair of elongated plate-like contact pieces C, C extend in the pin terminal insertion and extraction direction X and are symmetrically arranged in each of the pin terminal insertion spaces B formed in the insulating body A, in that the contact pieces C, C are electrically connected with each other by a short-circuit portion D made of a thin metal plate, and in that the short-circuit portion D and the contact pieces C, C are formed into one body by punching or bending a thin metal plate which is common to them. In the connector shown in FIG. 10, however, contacts F, F corresponding to a pin terminal G1 or G2 are at positions (given positions in the pin terminal insertion direction X2) which are located more rearward than rocking fulcrums E, E respectively located in the base portions.
In FIGS. 7 and 10, B1 designates the body of the counter multipolar electrical connector.
A number of pin terminals of a counter connector disposed on a computer apparatus in which a memory card is to be used project from the connector body by lengths varying depending on the kind of signals to be processed. This is because, when the pin terminals of the counter connector are inserted into the pin terminal insertion spaces of a connector to connect the counter connector with the connector, the contact timings between the pin terminals through which signals of different kinds pass and the corresponding contact pieces of the connector are temporarily shifted from each other in accordance with the kinds of the signals.
The connector described in conjunction with FIG. 7 has higher reliability with respect to that, when the two kinds of pin terminals, the short pin terminal G1 and the long pin terminal G2 indicated by phantom lines in the figure are to be inserted, the timings of contacting the pin terminals G1 and G2 with the contacts F . . . of the corresponding contact pieces C . . . (the contact pieces corresponding to the long pin terminal G2 are not shown) are surely temporarily shifted from each other. More specifically, the pin terminal G1 collides with the contacts F, F immediately before the pin terminal G1 is inserted into the lap position of the paired contact pieces C, C (the position where the contact pieces C, C overlap with each other in the thickness direction T of the body A). It is impossible for the pin terminal G1 to contact any portion of the contact pieces C, C before the pin terminal G1 collides with the contacts F, F. This is applicable also to the long pin terminal G2. As a result, it is possible to assure the above-mentioned temporal shift between the contact timings.
However, the contacts F, F are located more forward than the rocking fulcrums E, E which are respectively located in the base portions of the contact pieces C, C. Accordingly, when, in the insertion process of the pin terminals, the short pin terminal G1 collides with the contacts F, F, for example, a part of the force generated by the collision is received by the rocking fulcrums E, E, whereby a large force is generated so as to impede the insertion of the pin terminal G1. This causes the force (insertion force) required for inserting the pin terminal G1 to be increased. Also for the long pin terminal G2, there arises the same situation as that of the short pin terminal G1. Since the pin terminals G1 and G2 respectively correspond to pairs of the contact pieces C, C and a number of the pin terminals G1 . . . and G2 . . . strike the corresponding contacts F . . . in the insertion process of a multipolar electrical connector, it is necessary to exert a large insertion force, whereby the operability in the insertion process is impaired. To comply with this, a configuration may be adopted in which a single contact piece is allocated to one pin terminal so that the operability in the insertion process is improved. In this configuration, however, each pin terminal contacts with only one contacting point, and therefore contact stability is lowered.
The connector described in conjunction with FIG. 8 has a configuration in which the contact pieces C, C are difficult to bend in the directions separating from each other. In this connector, therefore, the force of inserting the pin terminals may be larger than that in the connector of FIG. 7, so that operability in the insertion process is further impaired as compared with that of FIG. 7. Since the edge faces which are formed as a result of a punching process of a thin metal plate function as the contacts F, F, moreover, the maximum width of the contacts F, F is restricted to the thickness of the thin metal plate. When a pin terminal inserted between the contacts F, F is deviated with a somewhat large degree in the width direction of the contacts F, F (the thickness direction, or the direction perpendicular to the sheet in FIG. 8), therefore, it is not possible to absorb the deviation.
In the configuration of the connector described in conjunction with FIG. 9, when a pin terminal is inserted, the two contacts F, F sequentially collide with the pin terminal. Therefore, the operability in the insertion process is improved as compared with that of FIG. 7. In order to equalize the effective lengths L1 and L2 of the contact pieces C, C to each other while keeping the contact pressures against the pin terminal equal to each other, however, the contact piece C having the contact F which is located rearward must be shifted backward from the position of the contact piece C having the contact F which is located forward, by the distance corresponding to the shifting distance between the contacts F, F. This increases the whole length of the connector, thereby impeding the miniaturization.
In the connector of FIG. 10, the contacts F, F are located more rearward than the rocking fulcrums E, E which are located in the base portions of the contact pieces C, C. According to this configuration, when the short pin terminal G1 collides with the contacts F, F in the insertion process, for example, it occurs only that the paired contact pieces C, C swing about the respective rocking fulcrums E, E, and the situation that the force generated by the collision of the pin terminal G1 against the contacts F, F is received by the rocking fulcrums E, E does not occur. Accordingly, a large force of hindering the pin terminal from being inserted is not generated, and therefore the insertion force for the pin terminal G1 can be smaller than that required in the connectors of FIGS. 7 and 8. Also for the long pin terminal G2, there arises the same situation as that of the short pin terminal G1. Although the pin terminals G1 and G2 respectively correspond to pairs of the contact pieces C, C and a number of the pin terminals G1 . . . and G2 . . . strike the corresponding contacts F . . . in the insertion process of a multipolar electrical connector, therefore, the required insertion force is not so large and operability is hardly impaired.
However, the connector has the following drawback. When the two kinds of pin terminals, the short pin terminal G1 and the long pin terminal G2 indicated by phantom lines in FIG. 10 are to be inserted, it is difficult to assure the temporary shift between the timings of contacting the pin terminals G1 and G2 with the contacts F of the corresponding contact pieces C . . . (the contact pieces corresponding to the long pin terminal G2 are not shown). More specifically, the pin terminal G1 collides with the contacts F, F after the pin terminal G1 is inserted into the lap position of the paired contact pieces C, C. If the pin terminal G1 is bent, therefore, there may arise a situation whereby the short pin terminal G1 contacts the corresponding contact piece C before the long pin terminal G2 collides with the corresponding contacts F, F. When such a situation occurs, it is impossible to assure the temporary shift between the contact timings of contacting the pin terminals G1 and G2 of the two kinds with the contacts.
As described above, in a prior art multipolar electrical connector for a memory card, the temporary shift between the timings of contacting contacts with pin terminals having different lengths can be assured at the sacrifice of operability in the insertion process. Further, a prior art multipolar electrical connector has a problem in that the prevention of an impaired operability in the insertion process is liable to be conducted at the sacrifice of the reliability with respect to the assurance of the temporary shift between the contact timings. Moreover, a prior art multipolar electrical connector has another problem in that, when the assurance of the temporary shift between the contact timings is attempted without sacrificing operability in the insertion process, miniaturization is impeded or the reliability of the contacting states between contacts and pin terminals is lowered.