Electrical connector

Abstract: For facilitating and electrical connection of a conductive connection pin (7) to a conductive contact (11) held to a base insulator (13), an electrical connector includes a preload pin (23) which is for carrying out beforehand displacement of a contact portion (21) of the conductive contact at a first position. The preload pin is held to a slider (19) which is placed between the base insulator and a cover insulator (17) and which is movable in a predetermined direction. The cover insulator and the slider have guide and elongated holes (15, 25), respectively, for passing the connection pin therethrough. The elongated hole is greater than the connection pin in a size of the predetermined direction. Therefore, it is possible without movement of the connection pin to move the preload pin in the predetermined direction to a second position at which the preload pin does not carry out the displacement of the contact portion.

Description: The present invention relates to an electrical connector for use in electrically connecting a conductive connection pin according to the preamble of claim 1, in particular one of a circuit package to an LSI circuit, a printed circuit board and the like. A conventional connector is schematically shown in Fig. 9, which depicts the case where an LSI circuit 2 is connected to a printed circuit board 1. A plurality of socket contacts 3 is embraced in a housing or base insulator 4. A cover insulator 6 is slidably combined with the base insulator 4. In the cover insulator 6, there is formed a plurality of penetrating guide holes 5. When a pin contact 7 of the LSI 2 is inserted into the corresponding guide hole 5, and the LSI circuit 2 is then moved in the direction of an arrow 8 together with the cover insulator 6, the pin contact 7 is brought into contact with the corresponding socket contact 3. More specifically, the pin contact 7 is brought into contact with the socket contact 3 as illustrated in Fig. 10. The pin contact 7 is in a laterally slidable manner inserted between a pair of resilient contact portions 9 extending from the socket contact 3 in the direction of the arrow 8 as illustrated in Fig. 10. As a result, the contact portions 9 are spread and slidably make press-contact with a peripheral surface of the pin contact 7. Fig. 11 shows a graph in the case where the pin contact 7 is inserted between the pair of confronting contact portions 9 of the socket contact 3 and removed therefrom, with the insertion force and removal force plotted as ordinate and the lateral movement of the contact pin 7 as abscissa. In Fig. 11, since the directions of the insertion force and removal force are opposite to each other, the respective directions are shown by a positive direction and a negative direction in the graph. As can be seen from Fig. 11, a maximum value F p of the insertion force is greater than the removal force F N , more specifically the maximum insertion force F p is approximately twice the removal force F N . Furthermore, when the frictional force of the contact portions 9 and the contact pin 7 is P and the coefficient of friction between the pin contact 7 and the socket contact 3 is µ, F N = 2µP. As a result, a large force is required for laterally inserting the pin contact 7 between the pair of contact portions 9 of the socket contact 3. Therefore, when a large number of socket contacts 3 are provided in this type of electrical connector, the insertion and removal operation is difficult. Furthermore, as shown in Fig. 12, the initial fitting space g between the opposing contact portions 9 of the socket contact 3 must be smaller than the diameter of the pin contact 7. On the other hand, there must be an appropriate inner protrusion h on each of the contact portions 9 in order that the pin contact 7 can be smoothly laterally inserted between the contact portions 9 of the socket contact 3. In other words, the initial outer diameter W₁ of the contact portions 9 of the socket contact 3 must be larger than the diameter t of the contact pin 7. As a result, when the pin contact 7 is inserted into the socket contact 3, the outer diameter of the socket contact 3 is increased to W₂. Therefore, it is difficult to position a number of the socket contacts 3 with high density. In the case where the socket contacts 3 are positioned with high density, the displacement (t - g)/2 of each resilient contact portion 9, which is equal to d/2, becomes extremely small, because the fitting space g between the contact portions 9 cannot be excessively reduced as can be seen from the above. Therefore, in order to obtain stable frictional force, the socket 3 must be fabricated by from a very hard spring, that is, a spring having a large spring constant. Therefore, if there is a fabrication error in the diameter of the pin contact 7 or a positional error thereof, the frictional force between the contact surfaces 9 and the contact pin 7 becomes insufficient for obtaining stable contact therebetween. In such a case, other problems occur. For example, the socket contact 3 may be excessively displaced so that excessive frictional force is caused between the contact surfaces 9 and the contact pin 7, and the resilient contact portions 9 are permanently deformed, or extremely large insertion and removal forces are required. These problems occur not only in the case where the LSI circuit 2 is connected to the printed circuit board 1 as explained above, but also in the case where printed circuit boards are connected to each other. An electrical connector for use in electrically connecting a conductive connection pin according to the generic portion of claim 1 is known from EP-A-0 122 486. In the known electrical connectors spacers are used to hold the resilient contact portions apart. Then the connection pins of the cover plate, having the same diameter as the spacers, are inserted between the resilient contact portions. The connection pins are used to shift the spacers out of the space between the resilient contact portions. This poses a high load onto the connection pins and the structure connecting them with the cover plate. Since the diameters of the spacers and the connection pins are the same there is no easy insertion of the connection pins into the space between the resilient contact portions. From US-A-4 381 130 an electrical connector is known wherein a tubular member comprises arms defining a space wherein the connection pin is to be inserted. The tubular member may be moved in a cam-like recess in a base plate. If the tubular member is shifted into the narrow part of the cam-like recess the pressure on to the tubular member results in an opening motion of the arms. The connection pin can be inserted. Thereafter, the tubular member is moved into the wider part of the recess so that the pressure on to the tubular member creases and the arms close around the connection pin. Accordingly, it is a principal object of this invention to provide an electrical connector which can connect a conductive terminal pin member thereof to an electrical circuit, which electrical connector can be positioned with high density. It is another object of this invention to provide an electrical connector which can attain stable electrical connection even when there is an error in the diameter of conductive pin members or in the positioning thereof, with minimum variation in the driving force required for the operation of the connector. It is a further object of this invention to provide an electrical connector which can obtain a stable frictional force with connecting members. According to this invention, there is provided an electrical connector for use in electrically connecting a conductive connection pin, having the features of claim 1. Preferred examples of the invention are specified in the subclaims. Fig. 1 is a perspective cross-sectional view of a main portion of an example of an electrical connector according to this invention; Fig. 2 is a plan sectional view of the electrical connector shown in Fig. 1; Fig. 3 is a cross-sectional view of a preload pin and a socket contact which are in contact; Fig. 4 is a side cross-sectional view of the preload pin and the socket contact in Fig. 3; Fig. 5 is a plan view of a connection pin of an LSI circuit and a socket contact which are in contact; Fig. 6 is a side cross-sectional view of the connection pin of the LSI circuit and the socket contact in Fig. 5; Fig. 7 is a perspective view of the connection pin of the LSI circuit and the socket contact in Fig. 5; Fig. 8 is a perspective view of another example of an electrical connector according to this invention; Fig. 9 is a perspective view of a conventional example of an electrical connector in use; Fig. 10 is a perspective view of the conventional electrical connector in explanation of the connection principle thereof; Fig. 11 is a diagram in explanation of the lateral insertion and removal forces of the conventional electrical connector shown in Fig. 9; and Fig. 12 is a diagram in explanation of the programs of the conventional electrical connector shown in Fig. 9 at the time of the insertion and removal thereof. With reference to Figs. 1 to 7, an example of an electrical connector according to the present invention will now be explained. Throughout these figures, the same reference numerals as in Fig. 9 designate identical or corresponding parts in Fig. 9, and the explanation of the identical or corresponding parts in the Fig. 9 is omitted. Referring to Figs. 1 to 4, the electrical connector of this invention comprises a base insulator 13 which supports a number of conductive socket contacts 11, and a cover insulator 17 having a number of penetrating guide holes 15. Each of the guide holes 15 extends in a first direction. The guide holes 15 are arranged in each of second and third directions which are perpendicular to each other. Each of the second and the third directions is perpendicular to the first direction. Between the base insulator 13 and the cover insulator 17, there is disposed a slider 19 which is movable in a direction as a third direction normal or perpendicular to the axis of the connection pin 7 of an LSI circuit 2. The slider 19 has a principal surface, namely, a lower surface. The slider 19 fixedly supports a guide pin 23 (hereinafter referred to as the preload pin 23) in the vicinity of the guide hole 15. The preload pin 23 protrudes from the principal surface of the slider 19 to be inserted between a pair of particular portions 22 of the socket contact 11. In this embodiment, the preload pin 23 is in the form of a cylinder which has a predetermined axis and a peripheral surface surrounding the predetermined axis. The preload pin 23 is not limited to such a form shown in the figure, but may be in other form. In the slider 19, an elongated hole 25 is formed in such a position as to face the corresponding guide holes 15. The elongated hole 25 allows the connection pin 7 of the LSI circuit 2 to be inserted therein and extends laterally as shown in Fig. 2. The socket contact 11 is made by punching or bending a conductive plate. The socket contact 11 includes a pair of support portions 27 and a pair of confronting plate-shaped spring arms 29. The pair of support portions 27 is fixedly inserted into a supporting hole 31 of the base insulator 11 as illustrated in Figs. 3 and 4. Only one of the support portions 27 is integrally provided with a terminal member 33 which projects from the lower end of the base insulator 11. The pair of spring arms 29 include a pair of contact portions 21 at the top thereof. The pair of contact portions 21 face each other with a space therebetween. Each spring arm 29 integrally includes a projected guide member 35 at an upper side portion thereof. Each pair of these projected guide members 35 extends with an inclination from the support portions 27 in such a direction as to be separated from each other. The preload pin 23 can be inserted between the pair of confronting particular portions 22 of the socket contact 11 by moving the preload pin 23 in the third direction normal to the predetermined axis of the preload pin 23 between the pair of the projected guide members 35 so as to be guided thereby. The preload pin 23 has a diameter which is larger than the space between the particular portions 21. In addition, the diameter of the preload pin 23 is larger than that of the pin contact 3. The cover insulator 17 is overlaid on the upper surface of the slider 19. The space between the contact portions 21 of the socket contact 11 is narrow when no external force is applied thereto. However, when the preload pin 23 is inserted between the particular portions 22, the space therebetween is spread. The contact portions 21 are thus displaced beforehand. As a result, the preload pin 23 is brought into press-contact with the particular portions 22 in the second direction by the righting moment of the contact portions 21. Prior to the insertion of the connection pin 7 of the LSI circuit 2, the slider 19 is overlaid on the upper surface of the base insulator 11. At this moment, the preload pin 23 of the slider 19 extends in front of the projected guide members 35 of the socket contact 11. The slider 19 is then moved in the third direction of an arrow 38 as illustrated in Fig. 2. when the slider 19 is moved in the third direction normal to the axis of the preload pin 23, the preload pin 23 is moved from the position of non-contact to the position of the particular portions 22. After the preload pin 23 is inserted between the particular portions 22 to spread the space between the contact portions 21, the cover insulator 17 is overlaid on the upper surface of the slider 19. Furthermore, the LSI circuit 2 is placed on the upper surface of the cover insulator 17. At this moment, the connection pin 7 of the LSI circuit 2 is passed through the guide hole 15 and the elongated hole 25 and reaches the contact portions 21. In the above-mentioned structure, it can be seen that the connection pin 7 of the LSI circuit 2 can be inserted with substantially no insertion force. The connection pin 7 of the LSI circuit 2 has a diameter which is substantially same to the space between the contact portions 21. Preferably, the diameter of the connection pin is slightly less than the space. The slider 19 is then moved in the direction of an arrow 40 as shown in Fig. 5. In accordance with the movement of the slider 19, the preload pin 23 is also moved slidably between the particular portions 21 in the third direction of the arrow 40. At this time, the elongated hole 25 of the slider 19 does not hinder the movement of the connection pin 23. When the slider 19 is further moved in the third direction of the arrow 40, the preload pin 23 is moved slidably along the particular portions 21 and eventually only the preload pin 23 is disengaged from the projected guide members 35 as illustrated in Figs. 5 to 7. Thus, the contact portions 21 are brought in press contact with the connection pin 7, so the necessary connection is achieved. This connection can be released by moving the slider 19 in the direction of the arrow 38 as shown in Fig. 2 again. When these connectors are disposed with high density as illustrated in Fig. 8, the operation force can be reduced by combining a plurality of block units with each block unit comprising the base insulator 11 and the slider 19. In other words, the maximum insertion and removal forces can be minimized. In the above, the case where the connection pin 7 is inserted for connection between a pair of spaced contact portions 21 has been explained. However, the present invention is not limited to the above case, but can be applied to the case where the connection pin 7 is connected by sliding it on one contact surface of the contact of the above-mentioned type. In this case, substantially the same effects can be obtained as in the above explained case. Thus, the electrical connector according to this invention has the advantages over conventional electrical connectors that a smaller force is required for connection and disconnection, multiple connections are easy and therefore a number of the connectors can be positioned with high density.

Claims: An electrical connector for use in electrically connecting a conductive connection pin (7), said connector comprising: a base insulator (13), a conductive contact (11) held to said base insulator (13) and having a resilient contact portion (21), a cover insulator (17) having a penetrating guide hole (15) which extends in a first direction for passing this connection pin (7) therethrough so that said connection pin (7) is brought in contact with said contact portion (21), the contact force between said connecting pin (7) and said contact portion (21) acting in a second direction which is perpendicular to said first direction, a slider (19) provided between said base insulator (13) and said cover insulator (17) and a preload pin (23) being connected to said slider (19), said slider (19) being movable between a first position in which said preload pin (23) is in contact with said contact portion (21) and a second position in which said preload pin (23) is disengaged from said contact portion (21) in a third direction perpendicular to said first and said second directions and having a principal surface facing said base insulator (13) and a hole (25) for passing said connection pin (7) therethrough, said preload pin (23) protruding from said principal surface in said first directionin the vicinity of one end of said hole (25), said preload pin (23) and said hole (25) being arranged in said third direction, and said hole (25) being greater than said connection pin (7) in a size of said third direction to permit said slider (19) be moved relative to said connection pin (7). whereby said preload pin (23) causes said contact portion (21) be at a predetermined position where said connection pin (7) is not brought in contact with said contact portion (21) only when said slider (19) is at said first position, characterized in that said preload pin (23) is greater than said connection pin (7) in a size of said second direction and that said hole (25) is elongated in said third direction. An electrical connector as claimed in claim 1, wherein said preload pin (23) has a peripheral surface surrounding an axis of said preload pin (23) extending in said first direction, said conductive contact (11) having a particular portion (35) adjacent to said contact portion (21), said peripheral surface of the preload pin (23) being brought in press contact with said particular portion (35) to displace said contact portion (21) to said predetermined position when said preload pin (23) faces said particular portion (35). An electrical connector as claimed in claim 2, wherein said conductive contact (11) has a guide portion (35) which is connected to said particular portion for guiding said peripheral surface of the preload pin (23) with said slider (19) moved in said third direction.

Inventors: HASHIGUCHI OSAMU C O JAPAN AVI, KOMOTO MITSUO C O NEC CORPORAT, NODA ATSUHITO C O JAPAN AVIATI, UMESATO SHOJI C O NEC CORPORAT, HASHIGUCHI, OSAMU, C/O JAPAN AVIATION ELECTRONICS, KOMOTO, MITSUO, C/O NEC CORPORATION, NODA, ATSUHITO, C/O JAPAN AVIATION ELECTRONICS, UMESATO, SHOJI, C/O NEC CORPORATION
Applicants: JAPAN AVIATION ELECTRON, NIPPON ELECTRIC CO, JAPAN AVIATION ELECTRONICS INDUSTRY, LIMITED, NEC CORPORATION
Application year: 1990
Main classification: H01R13
IPC codes: H01R24, H01R13