MULTI-PIN ELECRICAL CONNECTOR OF LOW INSERTION FORCE TYPE

Abstract: The connector comprises a male plug (A) having pin terminals (2, 3) of two different kinds, and a female socket (B) having contacts (11) of the same kind. Each pin terminal of one kind (2) has a straight inclination (6) extending from its tip end (23) at a relatively small angle (ϑ₁) whereas each pin terminal of the other kind (3) has a straight inclination (6) extending from its tip end (23) at a relatively large angle (ϑ₂). Thus, the resultant insertion force of pin terminals of the one kind (2) reaches its peak value earlier than the resul­ tant insertion force of pin terminals (3) of the other kind when the male plug (A) is inserted in the female socket (B). Advantageously, the straight inclination (6, 7) can be easily shaped with precision. This permits mass production of pin terminals (2, 3) of the same insertion force characteristics.

Description: The present invention relates to an electrical connector and particularly to a multi-pin electrical connector of low insertion force type which permits reduction of the force which is required in inserting its male plug in its female socket. As is well known, a variety of multi-pin electrical connectors have been proposed and used in practice. Such an electrical connector comprises a male plug having a plurality of pin terminals each having a tapering tip, and a female socket having a plurality of contacts each adapted to make a resilient contact with the tapering tip-and-consecutive straight side of a corresponding pin terminal. At an early stage of development all pin terminals have one and the same inclination angle at its tapering tip. Fig. 26 shows the insertion force-to-insertion depth characteristics of a known pin terminal when inserted in a female contact. As seen from the graph, the insertion force rises with the increase of the insertion depth, and it will reach its peak value when the pin terminal comes close to its final contact position, and accordingly the intervening angle between the tapering tip of the pin terminal and the contact surface decreases. When the intervening angle reduces to zero, the insertion force levels off as indicated at F₀. The peak value is indicated at F₁ in the graph, and sometimes the force of the peak value is called "insertion force". Here, it should be noted that all pin terminals in the socket reach their final positions simultaneously. As a result, the resultant insertion force required for inserting the male plug into the female socket is equal to a multiplication of the insertion force of a single pin terminal by the number of the pin terminals used in the socket. The graph shows the resultant insertion force 2 F₂ of two pin terminals compared with that required for insertion of a single pin terminal into a female contact. This shows the multiplied increase of insertion force required in a multi pin electrical connector. There was a strong demand for decreasing the insertion force required in a multi pin electrical connector. In an attempt to meet such a demand a variety of multi pin connectors were proposed, and are actually used. For instance, US Patent 4,679,890 shows a multi pin electrical connector of low insertion force type. It has a plurality of contacts each having a shape symmetrical with respect to its center axis, and a plurality of pin terminals each having different curvatures on its opposite sides with respect to its center axis. This arrangement caused the insertion force of the pin terminal to be reached twice at different times because one curvature comes to contact with the female contact earlier than the other curvature. This principle may be applied to an electrical connector whose pin terminals are so designed that each pin terminal contacts a counter female contact on its one side. In this case at least two kinds of pin terminals are prepared, and one kind of pin terminal has a first curvature on its contact side whereas the other kind of pin terminal has a second curvature on its contact side. These first and second curvatures are different from each other, hence causing insertion forces to appear at different times, thereby substantially decreasing the resultant insertion force compared with use of only one kind of tapering pin terminals, which would cause simultaneous increase of insertion forces, requiring a multiplied resultant insertion force. Pin terminals are punched from a piece of metal plate, and then their tapering tips are trimmed to the precisely desired curvature. Disadvantageously, however, it is very difficult to shape the tapering tip of a pin terminal into a precisely curved shape. It is likely that pin terminals have less precise curvatures, and this is a cause for failure in decreasing the resultant insertion force to a desired small value. In other words, extreme precision is required in making pin terminals of different kinds to attain a satisfactory result. One object of the present invention is to provide a multi-pin electrical connector which makes it easy to give a pin terminal as precise a shape as desired, thus assuring the substantial reduction of the resultant insertion force. To attain this object a multi-pin electrical connector of low insertion force type comprising a plug having a plurality of pin terminals, and a socket having a plurality of contacts, each being adapted to come into resilient contact with a corresponding pin terminal when said plug is inserted in said socket, said plurality of pin terminals being of at least two groups of such different terminal tip shapes that may cause the resultant insertion force of one group of pin terminals to reach its peak value at a time different from when the resultant insertion force of the other group of pin terminals reaches its peak value when said plug is inserted in said socket, is characterized according to the present invention in that each pin terminal of said one or the other group has a straight inclination extending from its tip end and a consecutive flat surface parallel to its center axis to provide together a contact surface with which a corresponding contact in said socket may come into resilient contact, the inclination angle of the straight inclination of each of the pin terminals of said one group being different from that of the pin terminals of said other group, thereby causing the resultant insertion force of said one group to reach its peak value at a time different from when the resultant insertion force of said other group reaches its peak value when said plug is inserted in said socket. According to one embodiment of the present invention the tip of each pin terminal has a first inclination extending from the tip end to one side of the pin terminal and a second inclination extending from the tip end to the other side of the pin terminal, said first and second inclinations having the same angle of inclination but the tapering tip end being beyond the central axis, thus arranging said first and second inclinations asymmetrically with respect to the central axis, and the inclination angle of said second inclination of each pin terminal of said one group being different from the inclination angle of said second inclination of each pin terminal of said other group. According to another embodiment of the present invention said pin terminals of said one and the other groups are alternately arranged in the same rows and the same lines in said plug. According to still another embodiment of the present invention said pin terminals of said one and the other group are alternately arranged in each line, but the same kind of pin terminals are arranged in each row. According to still another embodiment of the present invention said pin terminals of said one and the other groups are alternately arranged in each row, but the same kind of pin terminals are arranged in each line. As described above, a multi-pin electrical connector uses a plurality of pin terminals of at least two different kinds. Specifically one kind of pin terminals have a relatively small inclination angle whereas the other kind of pin terminals have a relatively large inclination angle. When the male plug is inserted into the female socket, the resultant insertion force of said other kind of pin terminals reaches its peak value earlier than the resultant insertion force of said one kind of pin terminals reaches its peak value. Thus, insertion of the male plug into the female socket requires a decreased insertion force, compared with that which would be required in inserting one and the same kind of pin terminals into corresponding female contacts. Advantageously, the straight inclination can be easily shaped in a pin terminal body with precision, compared with the curved surface which is given to the tip of a conventional pin terminal. Also, necessary punching dies to give a straight inclination to a pin terminal body can be easily designed and can be made with precision. Thus, pin terminals of different precise inclination angles can be easily prepared, and accordingly a lot of multi-pin electrical connectors having exactly the same insertion force characteristics can be provided. Some ways of carrying out the present invention will now be described in detail by way of example with reference to drawings which show one embodiment. In the drawings: FIGS. 1 to 13 show a male plug of a multi-pin electrical connector according to the present invention; FIG. 1 is a front view of the male plug; FIG. 2 is a plane view of the male plug; FIG. 3 is a rear view of the male plug; FIG. 4 is a side view of the male plug as seen from the right in Fig. 2; FIG. 5 is a section of the male plug taken along the line B-B in Fig. 2; FIG. 6 is a section of the male plug taken along the line A-A in Fig. 2; FIG. 7 is an enlarged front view of a fragment of the male plug; FIG. 8 is an enlarged rear view of a fragment of the male plug; FIG. 9 is a front view of a pin terminal having a second straight side inclined at a relatively large angle with respect to its center axis; FIG. 10 is a side view of the pin terminal of Fig. 9; FIG. 11 is a front view of a pin terminal having a straight side inclined at a relatively small angle with respect to its center axis; FIG. 12 is a side view of the pin terminal of Fig. 11; FIG. 13 is a perspective view of a pin terminal; FIGS. 14 to 22 show a female socket of the multi-pin electrical connector; FIG. 14 is a front view of the female socket; FIG. 15 is a plane view of the female socket; FIG. 16 is a rear view of the female socket; FIG. 17 is a side view of the female socket as seen from the right in Fig. 15; FIG. 18 is a section of the female socket taken along the line B-B in Fig. 15; FIG. 19 is a section of the female socket taken along the line A-A in Fig. 15; FIG. 20 is an enlarged front view of a fragment of the female socket; FIG. 21 is an enlarged rear view of a fragment of the female socket; FIG. 22 is a perspective view of a contact; FIG. 23 is a section of the male plug (Fig. 5) and the female socket (Fig. 18) mated together; FIG. 24 is a section of the male plug (Fig. 6) and the female socket (Fig. 19) mated together; FIG. 25 is a graph showing the insertion force-to-insertion depth characteristics of a multi-pin electrical connector of low insertion force type according to the present invention; and FIG. 26 is a graph showing the insertion force-to insertion depth characteristics of a conventional multi-pin electrical connector. Referring to Figs. 1 to 25, Figs. 1 to 13 show the male plug of a multi-pin electrical connector of low insertion force type according to one embodiment of the present invention; Figs. 14 to 22 show the female socket of the multi-pin electrical connector; Figs. 23 and 24 show how the pin terminals of the male plug are inserted in the contacts of the female socket of the multi-pin electrical connector; and finally Fig. 25 shows the insertion force-to-insertion depth characteristics of the multi-pin electrical connector. First, referring to Figs. 1 to 13, the male plug A comprises a plug housing 1, a plurality of pin terminals 2 of one kind, and a plurality of pin terminals 3 of another kind. In this particular embodiment the plug housing 1 has 30 pin terminals in its upper line X and 30 pin terminals in its lower line Y. Each pin terminal has a tapering tip and consecutive opposite sides 4 and 5 parallel to its center axis. The tapering tip of the pin terminal has opposite straight inclinations. One inclination is indicated at 6 in the pin terminal 2 or 3 of one or the other kind, and the other inclination is indicated at 7 in the pin terminal 2 of one kind, and is indicated at 8 in the pin terminal 3 of the other kind. In this particular embodiment only the inclinations of the pin terminals of the male plug may come into resilient contact with the contacts of a female socket, as later described. The inclination angle ϑ₁ of the straight inclination 7 (that is, the angle formed between the line of extension 1 from the straight inclination 7 and the flat surface of one side 5) is different from the inclination angle ϑ₂ of the straight inclination 8 (that is, the angle formed between the line of extension 1′ from the straight inclination 8 and the flat surface of one side 5), as seen from Figs. 10 and 12. In one example, the inclination angle ϑ₁ is 10° whereas the inclination angle ϑ₂ is 17°. As is best seen from Fig. 12, the tip 21 of the pin terminal 2 has a first inclination 6 extending from the tip end 23 to one side 4 of the pin terminal 2 and a second inclination 7 extending from the tip end 23 to the other side 5 of the pin terminal 2. The first and second inclinations 6 and 7 have a same angle with respect to the central axis C, but the tapering tip end is set apart from the central axis C. Thus, the first and second inclinations 6 and 7 are asymmetrical with respect to the central axis C. Also, as is best seen from Fig. 10, the tip 21 of each pin terminal 3 has a first inclination 6 extending from the tip end 23 to one side 4 of the pin terminal 3 and a second inclination 8 extending from the tip end 23 to the other side 5 of the pin terminal 3. The first and second inclinations 6 and 8 have the same angle with respect to the central axis C, but the tapering tip end 22 is set apart from the central axis C. Thus, the first and second inclinations 6 and 8 are asymmetrical with respect to the central axis C. Here, it should be noted that the inclination angle of the second inclination 7 of the pin terminal 2 of one kind is different from the inclination angle of the second inclination 8 of the pin terminal 3 of the other kind. Advantageously, the straight inclination facilitates the precise shaping of the tapering tip of the pin terminal, permitting mass production of pin terminals of exactly same insertion force characteristics. As seen from Figs. 1 and 7, a pin terminal 2 having an inclination angle ϑ₁ is placed at the right end of the lower line Y, and a pin terminal 3 having an inclination angle ϑ₂ is placed on the left side of the pin terminal 2 in the same lower line Y. Pin terminals of one and the other kinds are alternately placed in the lower line Y. Likewise, a pin terminal 3 having an inclination angle ϑ₂ is placed at the right end of the upper line X, and a pin terminal 2 having an inclination angle ϑ₁ is placed on the left side of the pin terminal 3 in the same upper line X. Pin terminals of one and the other kinds are alternately placed in the upper line X. Thus, pin terminals 2 and 3 of one and the other kinds are placed up and down or vice versa on each row. In short, the male plug A has pin terminals 2 and 3 of one and the other kinds alternately arranged in the same rows and the same lines. As is best seen from Figs. 14 to 22, the female socket B has 30 contacts placed in the upper line X′ and 30 contacts placed in the lower line Y′. These contacts have the same shape to make contact with corresponding pin terminals of the one and the other kinds. Figs. 23 and 24 show how pin terminals 2 and 3 of different kinds are inserted in corresponding contacts 11 when the male plug A and the female plug B are mated. Fig. 23 is equivalent to a composite section of the male plug taken along the line B-B in Fig. 2 and the female socket taken along the line B-B in Fig. 15 whereas Fig. 24 is equivalent to a composite section of the male plug taken along the line A-A in Fig. 2 and the female socket taken along the line B-B in Fig. 15. As shown in these figures, the pin terminals 2 and 3 are put in resilient contact with the contacts 11 in the cells 10 of the female socket B. Fig. 25 shows the insertion force-to-insertion depth characteristics of the multi-pin electrical connector. In this graph the insertion force to be applied to a pin terminal having an inclination angle ϑ₁ varies with the increase of insertion depth as indicated at S₁, whereas the insertion force to be applied to a pin terminal having an inclination angle ϑ₂ varies with the increase of insertion depth as indicated S₂. Because of difference in inclination angles in pin terminals 2 and 3 of the one and the other kinds their peak values appear at different times. Thus, the resultant curve S₃ shows a relatively small peak value F₁. As already described, each pin terminal has first and second straight inclinations on opposite sides of the tapering tip of the pin terminal. These straight inclinations can be easily shaped with precision because of their simple shape, and therefore a lot of pin terminals of exactly the same insertion force characteristics can be made without difficulty. This assures that every multi-pin electrical connector causes the appearance of its peak insertion force value at exactly controlled times in the course of insertion. The same result could be hardly attained with pin terminals having different curvatures. In a further embodiment of the present invention having an arrangement of the pin terminals which is different from the one described above with reference to Fig. 1, a pin terminal 2 having an inclination angle ϑ₁ is placed at a given position in the lower line Y, and a pin terminal 3 having an inclination angle ϑ₂ is placed on the same position in the upper line X. Pin terminals of the one and the other kinds are alternately placed in the upper and lower lines. Thus, the pin terminals 2 and 3 of the one and the other kinds are alternately arranged in each line, but the same kind of pin terminals 2 or 3 are arranged in each row. In a still further embodiment, pin terminals 2 and 3 of the one and the other kinds are alternately arranged in each row but the same kind of pin terminals 2 or 3 are arranged in each of upper and lower lines.

Claims: A multi-pin electrical connector of low insertion force type comprising a plug having a plurality of pin terminals, and a socket having a plurality of contacts, each being adapted to come into resilient contact with a corresponding pin terminal when said plug is inserted in said socket, said plurality of pin terminals being of at least two groups of such different terminal tip shapes that may cause the resultant insertion force of one group of pin terminals to reach its peak value at a time different from when the resultant insertion force of the other group of pin terminals reaches its peak value when said plug is inserted in said socket, characterised in that each pin terminal (2 or 3) of said one or the other group has a straight inclination (7 or 8) extending from its tip end and a consecutive flat surface parallel to its center axis to provide together a contact surface with which a corresponding contact (11) in said socket (B) may come into resilient contact, the inclination angle ϑ₁ of said straight inclination (7) being different from the inclination angle ϑ₂ of said straight inclination (8) thereby causing the resultant insertion force of one group of pin terminals (2) to reach its peak value at a time different from when the resultant insertion force of the other group of pin terminals (3) reaches its peak value when said plug is inserted in said socket. A multi-pin electrical connector of low insertion force type according to claim 1 wherein the tip (21) of each pin terminal (2 or 3) has a first inclination (6) extending from the tip end (23) to one side (4) of the pin terminal and a second inclination (7 or 8) extending from the tip end (23) to the other side (5) of the pin terminal, said first and second inclinations having a same angle, but the tapering tip end being apart from the central axis (C), thus arranging said first and second inclinations asymmetrically with respect to the central axis (C), and the inclination angle of said second inclination (7) of each pin terminal (2) of said one group being different from the inclination angle of said second inclination (8) of each pin terminal (3) of said the other group. A multi-pin electrical connector of low insertion force type according to claim 1 or 2 wherein said pin terminals (2 and 3) of said one and the other group are alternately arranged in same rows and same lines in said plug A. A multi-pin electrical connector of low insertion force type according to claim 1 or 2 wherein said pin terminals (2 and 3) of said one and the other group are alternately arranged in each line, but the same kind of pin terminals (2 or 3) are arranged in each row. A multi-pin electrical connector of low insertion force type according to claim 1 or 2 wherein said pin terminals (2 and 3) of said one and the other group are alternately arranged in each row, but the same kind of pin terminals (2 or 3) are arranged in each line.

Inventors: SASAO, MASAMI, YAMADA, SHOJI B-101 CALM TERRACE, YAMAMOTO, YOSHIHISA 302 DEHEN HEIGHTS
Applicants: MOLEX INCORPORATED
Application year: 1989
Main classification: H01R13
IPC codes: H01R24, H01R13