Coaxial electric connector

Abstract

To provide a coaxial electric connector which can easily secure an excellent signal transmission characteristic into a wider bandwidth.SOLUTION: A dielectric body 30 includes a first dielectric body 31 and a second dielectric body 32, the second dielectric body forming a space between the first and second dielectric bodies in a position separate from the first dielectric body 31 in a connection direction. The first electric body 31 and the second dielectric body 32 hold a central conductor 20 in a radial direction. The first dielectric body 31 has a smaller dielectric constant than that of the second dielectric body 32, and the second dielectric body 32 is harder than the first dielectric body 31.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a coaxial electrical connector.

Background Art

[0002] A coaxial electrical connector in which a dielectric (insulating member), a center conductor, and an annular fitting are provided in the internal space of an outer conductor is disclosed, for example, in Patent Document 1. The internal space of the outer conductor is formed by penetrating the outer conductor in the vertical direction perpendicular to the mounting surface of the circuit board. In the internal space, a resin-made dielectric having a cylindrical shape is disposed at a position closer to the lower end, and a center conductor extending in the vertical direction is held by the dielectric in a state of being inserted into the holding hole of the dielectric. Further, an annular fitting is attached from below to prevent the dielectric and the center conductor from coming off.

[0003] The center conductor has an inclined protrusion protruding radially outward of the center conductor at a portion inserted and held in the holding hole of the dielectric, and the inclined protrusion is supported from above by a stepped portion (depression) formed on the inner peripheral surface of the holding hole in a state of abutting against the stepped portion from below. The lower end portion of the center conductor slightly protrudes from the lower surface of the outer conductor, and when the coaxial electrical connector is mounted on the circuit board, with the vertical direction as the connection direction, it comes into contact with the circuit portion on the mounting surface of the circuit board with a contact pressure from above. At this time, the center conductor always receives a reaction force upward from the mounting surface of the circuit board, but the stepped portion of the dielectric supports the inclined protrusion of the center conductor from above to counteract the reaction force, thereby generating a contact pressure between the center conductor and the circuit portion of the circuit board.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In Patent Document 1, the dielectric is configured as a single member and has both the function of holding the central conductor as described above and the function of generating contact pressure between the central conductor and the circuit portion of the circuit board. This dielectric has a cylindrical shape that extends long in the vertical direction and is provided so as to fill the space between the inner peripheral surface of the outer conductor and the outer peripheral surface of the central conductor in the radial direction. Therefore, within the range of the dielectric in the vertical direction, since there is no air layer between the inner peripheral surface of the outer conductor and the outer peripheral surface of the central conductor in the above-described radial direction, the usable frequency band is narrow. As a result, the signal transmission characteristics of the coaxial electrical connector in a wide band are degraded.

[0006] In view of such circumstances, an object of the present invention is to provide a coaxial electrical connector that can easily ensure good signal transmission characteristics up to a wide band.

Means for Solving the Problems

[0007] (1) A coaxial electrical connector that is connected to a connection target with a predetermined one direction as a connection direction, a metal outer conductor in which an internal space having an axis extending in the connection direction is formed to penetrate in the connection direction, a dielectric directly or indirectly held by the outer conductor within the internal space, and a metal central conductor that extends in the connection direction within the internal space, is held by the dielectric, and contacts the connection target at a front end portion in the connection direction.

[0008] In such a coaxial electrical connector, in the present invention, the dielectric has a first dielectric and a second dielectric provided so as to form a space between the first dielectric and the first dielectric at a position separated from the first dielectric in the connection direction. The first dielectric and the second dielectric hold the central conductor in the radial direction. The first dielectric has a lower dielectric constant than the second dielectric, and the second dielectric has a higher hardness than the first dielectric.

[0009] In the invention of (1), the first dielectric and the second dielectric are provided so as to be separated from each other in the connection direction, and a space is formed between the first dielectric and the second dielectric. That is, in the range where this space is formed in the connection direction, an air layer exists between the inner peripheral surface of the outer conductor and the outer peripheral surface of the central conductor in the radial direction. Therefore, compared with the case where one dielectric extending long in the connection direction as in the prior art is provided between the outer conductor and the central conductor, the usable frequency band can be widened by the amount of the existence of the air layer without changing the size of the connector. As a result, good signal transmission characteristics can be ensured up to a wide band.

[0010] Further, in the present invention, since the first dielectric has a lower dielectric constant than the second dielectric, to that extent, it is possible to suppress the degree to which the usable frequency band is narrowed due to the provision of the dielectric. Further, in the present invention, since the second dielectric has a higher hardness than the first dielectric, the holding force of the central conductor by the second dielectric can be improved. Therefore, in the present invention, it is possible to ensure good signal transmission characteristics up to a wide band as much as possible while maintaining the central conductor at the normal position well.

[0011] (2) In the invention of (1), the central conductor may have a contact portion that can contact the second dielectric from the front in the connection direction. When the coaxial electrical connector is connected to a connection target forward in the connection direction, the central conductor may receive a force directed rearward from the connection target. At this time, the contact portion of the central conductor contacts the second dielectric from the front and receives a reaction force directed forward from the second dielectric. Therefore, this reaction force directed forward counteracts the force directed rearward from the connection target, and as a result, it becomes easier to maintain the central conductor at the normal position in the connection direction.

[0012] (3) In the invention of (1) or (2), the first dielectric may be provided in front of the second dielectric in the connection direction.

[0013] (4) In any of the inventions (1) to (3), the first dielectric may have a dimension in the connection direction smaller than that of the second dielectric. Thus, by reducing the dimension of the first dielectric in the connection direction, the dimension of the air layer formed between the first dielectric and the second dielectric can be increased accordingly. Therefore, the usable frequency band becomes wider, and as a result, good signal transmission characteristics can be ensured even in a wider bandwidth.

[0014] (5) In any of the inventions (1) to (4), the second dielectric may have a higher deflection temperature under load than the first dielectric. Thus, when the deflection temperature under load of the second dielectric is high, it is less likely to plastically deform even when the usage environment of the coaxial electrical connector is at a high temperature. Therefore, the holding force of the center conductor by the second dielectric is less likely to decrease, making it easier to maintain the center conductor in its normal position.

[0015] (6) In any of the inventions (1) to (5), the first dielectric may be made of polytetrafluoroethylene, and the second dielectric may be made of polyetherimide.

Effect of the Invention

[0016] The present invention can provide a coaxial electrical connector that can easily ensure good signal transmission characteristics up to a wide bandwidth.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0018] Hereinafter, embodiments of the present invention will be described based on the accompanying drawings.

[0019] FIG. 1 is a perspective view showing a coaxial electrical connector 1 (hereinafter referred to as "coaxial connector 1") according to an embodiment of the present invention together with an electronic device 2 which is a connection target. FIG. 1(A) shows the state before being attached to the electronic device 2, and FIG. 1(B) shows the state after being attached to the electronic device 2 as viewed obliquely from the rear. In FIGS. 1(A) and 1(B), only a part of the electronic device 2 is shown. As shown in FIG. 1(B), the coaxial connector 1 is to be screwed and attached to the rear surface (a plane perpendicular to the front-rear direction) of the electronic device 2. In this way, by attaching the coaxial connector 1 to the electronic device 2 from the rear side (X2 side), the coaxial connector 1 is electrically connected to the electronic device 2. That is, the direction facing forward (X1 direction) is the connection direction of the coaxial connector 1 with respect to the electronic device 2.

[0020] The coaxial connector 1 has an axis extending in the front-rear direction (X-axis direction), and has a symmetrical shape in the connector width direction (Y-axis direction) perpendicular to both the front-rear direction (X-axis direction) and the up-down direction (Z-axis direction). The coaxial connector 1 includes a metal outer conductor 10, a metal center conductor 20 disposed in an inner space 15 (see FIG. 3(A)) described later of the outer conductor 10 so as to be concentric with the inner space 15, a resin dielectric 30, and a metal support 40. Further, the dielectric 30 has a first dielectric 31 and a second dielectric 32 formed of different materials from each other.

[0021] The outer conductor 10 has a plate-like base portion 11 that extends at a right angle to the front-rear direction, and a cylindrical cylindrical portion 12 that extends rearward from the rear surface of the base portion 11. As shown in FIGS. 1(A) and 1(B), the base portion 11 extends in the connector width direction as the longitudinal direction, and mounting hole portions 13, which are screw holes penetrating the base portion 11 in the front-rear direction, are provided one by one on both end sides of the cylindrical portion 12 in the connector width direction. In the present embodiment, the coaxial connector 1 is attached to the housing 60 by screwing a screw member 50 into the mounting hole portion 13 and a screw hole 62B provided in the housing 60 of the electronic device 2 described later corresponding to the mounting hole portion 13 from the rear.

[0022] FIG. 2 is a perspective view showing the coaxial connector 1 of FIG. 1 as viewed obliquely from the front. As shown in FIG. 2, a protrusion 14 that slightly protrudes more than other regions is formed in a region that spreads in the center on the front surface (the surface on the X1 side) of the base portion 11. The protrusion 14 has an annular shape surrounding a small-diameter space 15C (the front end portion of the inner space 15) described later when viewed from the front. This protrusion 14 is concentric with the center conductor 20 when viewed from the front. In the present embodiment, when the coaxial connector 1 is screwed and attached to the housing 60 of the electronic device 2, the front surface of the protrusion 14 is pressed against the rear surface of the housing 60. By providing the protrusion 14 on the front surface of the base portion 11 in this way, it becomes easier to surely bring the outer conductor 10 into contact with the housing 60 in the vicinity of the center conductor 20 and ensure a good electrical conduction state.

[0023] The cylindrical portion 12 has a central axis extending in the front-rear direction and is cylindrical, extending rearward from the rear surface of the base portion 11. In the cylindrical portion 12, an intermediate portion located closer to the rear end in the front-rear direction has a larger diameter than other portions.

[0024] Figs. 3(A) and (B) are partial cross-sectional views of the coaxial connector 1 and the electronic device 2 in Fig. 1(B), showing a cross-section in a plane perpendicular to the vertical direction (the short-side direction of the base portion 11) at the position of the axis of the coaxial connector 1. As shown in Fig. 3(A), the outer conductor 10 has a central axis extending in the front-rear direction, and an internal space 15 is formed that penetrates the base portion 11 and the cylindrical portion 12 in the front-rear direction. The internal space 15 has a large-diameter space 15A, a medium-diameter space 15B, and a small-diameter space 15C, each having a different inner diameter dimension. The large-diameter space 15A, the medium-diameter space 15B, and the small-diameter space 15C are formed in this order from the rear to the front and communicate with each other.

[0025] The large-diameter space 15A is a cylindrical space formed in a range extending from the rear-end position to a position closer to the front end of the cylindrical portion 12 in the front-rear direction. As shown in Fig. 3(A), in the large-diameter space 15A, the space at the rear is slightly larger in diameter than the space at the front. A large-diameter portion 41 of the support 40, which will be described later, is accommodated in a part of the rear space and the front space. Also, the rear space serves as a space for receiving a mating coaxial connector (not shown) when the mating coaxial connector is fitted and connected to the coaxial connector 1 from the rear. When the mating coaxial connector is fitted and connected, the rear surface of the support 40 supported by the outer conductor 10 contacts the front surface of the mating outer conductor (not shown) of the mating coaxial connector, enabling electrical conduction.

[0026] As shown in Fig. 3(A), the medium-diameter space 15B has a smaller diameter than the large-diameter space 15A, and is formed in a range extending from the front-end position of the large-diameter space 15A to a position closer to the front end of the cylindrical portion 12 in the front-rear direction. The space in the front part of the medium-diameter space 15B is cylindrical, and the space in the rear part of the medium-diameter space 15B has a tapered shape in which the inner diameter dimension gradually increases toward the rear. The small-diameter space 15C is a cylindrical space having a smaller diameter than the medium-diameter space 15B, and is formed in a range extending from the front-end position of the medium-diameter space 15B to the front-end position of the base portion 11 in the front-rear direction. A step portion 16 is formed at the boundary position between the medium-diameter space 15B and the small-diameter space 15C. The step portion 16 is in contact with the front surface of the support body 40 and supports the support body 40 from the front. Note that the step portion 16 supports not only the support body 40 but also a first dielectric body 31 described later from the front, but it is not essential to support the first dielectric body 31.

[0027] The center conductor 20 is provided to extend in the front-rear direction at a position concentric with the internal space 15 when viewed in the front-rear direction. As shown in Fig. 3(A), the center conductor 20 has a connection portion 21 provided at the rear portion to which a mating-side center conductor (not shown) of a mating coaxial connector is connected, a contact portion 22 provided at the front portion that can contact a mating-side center conductor 80 (see Fig. 4) provided in the electronic device 2, and a connecting portion 23 provided between the connection portion 21 and the contact portion 22 to connect the two.

[0028] As shown in Fig. 3(A), the connection part 21 is accommodated within the large-diameter space 15A of the external conductor 10. More specifically, it is housed within the rear space 43A of the support 40 disposed within the large-diameter space 15A. The rear end of the connection part 21 is at the same position as the rear end of the rear space 43A in the front-rear direction. The connection part 21 has a female shape. Specifically, the rear part of the connection part 21 is cylindrical, with slits 21A formed at a plurality of positions in the circumferential direction, and connection pieces 21B are formed between adjacent slits 21A. In the space surrounded by the plurality of connection pieces 21B, the mating central conductor (not shown) of the mating coaxial connector is inserted from the rear. At this time, the plurality of connection pieces 21B are pushed radially outward of the connection part 21 by the mating central conductor and are in a state of elastic deformation, and come into contact with the outer peripheral surface of the mating central conductor with contact pressure.

[0029] The contact part 22 has a smaller diameter than the connection part 21 and is accommodated within the small-diameter space 15C as shown in Fig. 3(A). The front end of the contact part 22 is at the same position as the front end of the small-diameter space 15C in the front-rear direction. The contact part 22 has a female shape. Specifically, the front part of the contact part 22 is cylindrical, with slits 22A formed at a plurality of positions in the circumferential direction, and contact pieces 22B are formed between adjacent slits 22A. In the space surrounded by the plurality of contact pieces 22B, the mating central conductor 80 of the electronic device 2 is inserted from the front. At this time, the plurality of contact pieces 22B are pushed radially outward of the contact part 22 by the male mating contact part 82 (see Fig. 4) provided on the mating central conductor 80 and are in a state of elastic deformation, and come into contact with the outer peripheral surface of the mating contact part 82 with contact pressure.

[0030] As shown in Fig. 3(A), the connecting portion 23 is accommodated in the front space 43B and the intermediate space 43C of the support 40, which will be described later, and has three cylindrical portions with different outer diameter dimensions. Specifically, as shown in Fig. 3(B), the connecting portion 23 has a first attachment portion 23A located on the front end side of the connecting portion 23, a second attachment portion 23B located on the rear end side of the connecting portion 23, and an intermediate portion 23C located between the first attachment portion 23A and the second attachment portion 23B in the front-rear direction. The outer diameter dimensions of these cylindrical portions increase in the order of the intermediate portion 23C, the first attachment portion 23A, and the second attachment portion 23B. Further, the first attachment portion 23A has the same diameter as the contact portion 22, and the second attachment portion 23B has a smaller diameter than the contact portion 22. The intermediate portion 23C has a slightly larger diameter than the contact portion 22 and a smaller diameter than the connection portion 21. A first dielectric 31 is attached to the outer peripheral surface of the first attachment portion 23A. A second dielectric 32 is attached to the outer peripheral surface of the second attachment portion 23B.

[0031] As shown in Fig. 3(B), a tapered first contact portion 23C-1 with an outer diameter dimension gradually decreasing toward the front is formed at the front end portion of the intermediate portion 23C, that is, the portion connected to the first attachment portion 23A. The first contact portion 23C-1 is in contact by contacting the tapered surface formed on the inner peripheral surface (to be described later) of the rear end portion of the first dielectric 31 from the rear. In other words, the first dielectric 31 supports the first contact portion 23C-1 from the front. Further, as shown in Fig. 3(B), a second contact portion 23C-2 having a stepped shape is formed at the rear end portion of the intermediate portion 23C at the boundary position with the second attachment portion 23B. The second contact portion 23C-2 is in contact by contacting the front surface of the second dielectric 32 from the front. In other words, the second dielectric 32 supports the second contact portion 23C-2 from the rear.

[0032] The first dielectric 31 is made of, for example, polytetrafluoroethylene (PTFE) and is formed into an annular plate shape. In the present embodiment, the polytetrafluoroethylene, which is the material of the first dielectric 31, has a dielectric constant of about 2.1 and a heat distortion temperature under load of about 55°C. As shown in FIGS. 3(A) and 3(B), the first dielectric 31 is slightly smaller, that is, thinner than the second dielectric 32 in the front-rear direction.

[0033] The first dielectric 31 is formed with an outer diameter slightly larger than the inner diameter of the front space 43B, which will be described later, of the support 40, and is press-fitted and housed in this front space 43B. As shown in FIG. 3(B), a first through-hole portion 31A penetrating the first dielectric 31 in the front-rear direction is formed in the first dielectric 31. The first through-hole portion 31A is formed with an inner diameter slightly smaller than the outer diameter of the first attachment portion 23A of the center conductor 20. That is, the first attachment portion 23A is press-fitted into the first through-hole portion 31A.

[0034] In the present embodiment, the first dielectric 31 has a continuous annular plate shape over the entire circumferential direction. However, instead of this, for example, a cut portion may be formed at one location in the circumferential direction. In this case, the cut portion may be formed so as to completely separate the first dielectric 31 in the circumferential direction, or may be partially formed so as to separate only a part thereof.

[0035] The second dielectric 32 is separate from the first dielectric 31 and is provided at a position behind the first dielectric 31 and spaced apart from the first dielectric 31. The second dielectric 32 is made of, for example, polyetherimide (PEI) and is formed into an annular plate shape. In the present embodiment, the polyetherimide, which is the material of the second dielectric 32, has a dielectric constant higher than that of the first dielectric 31 (about 3.1), and a heat distortion temperature under load higher than that of the first dielectric 31 (about 197 to 200°C). In other words, the first dielectric 31 has a lower dielectric constant and a lower heat distortion temperature under load than the second dielectric 32. Also, the second dielectric 32 has a higher hardness than the first dielectric 31. Here, the "hardness" is defined, for example, as the so-called rebound hardness.

[0036] The second dielectric body 32 is formed with an outer diameter slightly smaller than the outer diameter of the first dielectric body 31. Further, the outer diameter of this second dielectric body 32 is equal to the inner diameter of a front space 43B (described later) of the support 40. A second through-hole portion 32A penetrating the second dielectric body 32 in the front-rear direction is formed in the second dielectric body 32. The second through-hole portion 32A is formed with an inner diameter slightly smaller than the outer diameter of the second attachment portion 23B of the center conductor 20. That is, the second attachment portion 23B is press-fitted into the second through-hole portion 32A.

[0037] Further, a cut portion (not shown) is formed at one location in the circumferential direction in the second dielectric body 32. Therefore, the second dielectric body 32 is discontinuous at the position of the cut portion in the circumferential direction. Note that the cut portion may be formed so as to completely cut off the second dielectric body 32 in the circumferential direction, or may be partially formed so as to cut off only a part thereof.

[0038] The support 40 has a substantially cylindrical shape and is accommodated in the internal space 15 of the external conductor 10. As shown in Fig. 3(A), the support 40 has a large-diameter portion 41 at the rear part and a small-diameter portion 42 having a smaller diameter than the large-diameter portion 41 at the front part. The outer diameter of the large-diameter portion 41 is slightly smaller than the space at the front part of the large-diameter space 15A, and it is accommodated in the large-diameter space 15A. In the present embodiment, the large-diameter portion 41 has a portion that is slightly larger in diameter than other portions at the rear-end side portion, and this portion is press-fitted into the large-diameter space 15A and held by the external conductor 10. The small-diameter portion 42 has a shape adapted to the medium-diameter space 15B. That is, the front part of the small-diameter portion 42 has a cylindrical shape, and the rear part of the small-diameter portion 42, that is, the portion connected to the large-diameter portion 41, has a tapered shape in which the outer diameter dimension gradually increases toward the rear. The outer diameter of the small-diameter portion 42 is slightly smaller than the medium-diameter space 15B, and it is accommodated in the medium-diameter space 15B.

[0039] The support body 40 is formed with an internal space 43 that has the same axis as the internal space 15 of the external conductor 10 and penetrates the support body 40. As shown in FIGS. 3(A) and (B), the internal space 43 includes a rear space 43A formed in substantially the same range as the large-diameter portion 41 in the front-rear direction, a front space 43B formed in substantially the same range as the small-diameter portion 42 in the front-rear direction, and an intermediate space 43C formed near the boundary position between the large-diameter portion 41 and the small-diameter portion 42 in the front-rear direction. The rear space 43A is formed at the rear part of the internal space 43 and houses the connection part 21 of the center conductor 20. The front space 43B is formed at the front part of the internal space 43 with a slightly smaller diameter than the rear space 43A and houses the connection part 23 of the center conductor 20, the first dielectric 31, and the second dielectric 32.

[0040] At the position between the rear space 43A and the front space 43B in the front-rear direction, a support portion 44 that projects radially inward from the inner peripheral surface of the internal space 43 is provided. The support portion 44 is formed over the entire circumferential direction of the internal space 43, and the space surrounded by the support portion 44 forms the intermediate space 43C. The intermediate space 43C has a smaller diameter than the rear space 43A and the front space 43B and houses the rear end portion of the connection part 23 of the center conductor 20. As shown in FIG. 3(B), the support portion 44 is in contact with the rear surface of the second dielectric 32 at its front surface and supports the second dielectric 32.

[0041] The coaxial connector 1 is manufactured as follows. First, the second dielectric 32 is attached to the second attachment portion 23B by inserting the center conductor 20 into the second through-hole portion 32A of the second dielectric 32 from the front end side, that is, the contact portion 22 side. In the present embodiment, the second through-hole portion 32A has a smaller diameter than the contact portion 22, the first attachment portion 23A, and the intermediate portion 23C of the connecting portion 23. However, a cut portion is formed in the second dielectric 32. When the contact portion 22, the first attachment portion 23A, and the intermediate portion 23C are inserted into the second through-hole portion 32A, the second dielectric 32 is deformed so as to open in the circumferential direction at the position of the cut portion, thereby allowing the insertion of the contact portion 22, the first attachment portion 23A, and the intermediate portion 23C. Further, in the present embodiment, since the first contact portion 23C-1 has a tapered shape, when the second dielectric 32 passes through the position of the first contact portion 23C-1, the first contact portion 23C-1 abuts against the peripheral surface of the second through-hole portion 32A, so that the second dielectric 32 smoothly opens at the position of the cut portion. Note that it is not essential for the first contact portion 23C-1 to have a tapered shape as long as the second dielectric 32 opens at the position of the cut portion when passing through the position of the first contact portion 23C-1. For example, it may have a stepped shape.

[0042] Then, when the second dielectric 32 passes through the range of the intermediate portion 23C and reaches the range of the second attachment portion 23B, the second dielectric 32 is deformed so as to close at the position of the cut portion. As a result, the inner peripheral surface of the second dielectric 32 comes into contact with the outer peripheral surface of the second attachment portion 23B, and the second dielectric 32 holds the second attachment portion 23B. In the present embodiment, the second dielectric 32 that has reached the range of the second attachment portion 23B is deformed so as to close at the position of the cut portion by its own restoring force. Instead of this, an operator may perform an operation of closing the cut portion.

[0043] In the present embodiment, the second attachment portion 23B of the center conductor 20 is formed with an outer diameter slightly larger than the inner diameter of the second through-hole portion 32A, and thus it is press-fitted into the second through-hole portion 32A. Therefore, the second dielectric 32 receives a pressing force directed radially outward by the outer peripheral surface of the second attachment portion 23B. In this state, the cut portion of the second dielectric 32 is slightly open.

[0044] In a state where the second dielectric body 32 is attached to the second attachment portion 23B, the rear surface of the second contact portion 23C-2 of the center conductor 20 is in surface contact and abuts against the front surface of the second dielectric body 32. Note that, at this point, it is not essential that the second contact portion 23C-2 abuts against the second dielectric body 32. Instead, when the coaxial connector 1 is connected to the electronic device 2, the second contact portion 23C-2 may abut against the second dielectric body 32 for the first time and support the second dielectric body 32 from the front.

[0045] Next, the center conductor 20 with the second dielectric body 32 attached is inserted forward into the internal space 43 of the support 40. At this time, the center conductor 20 is inserted until the second dielectric body 32 reaches the rear part of the front space 43B of the internal space 43. As a result, the connecting portion 23 of the center conductor 20 is accommodated in the front space 43B and the intermediate space 43C. In the present embodiment, since the outer diameter of the second dielectric body 32 is equal to the inner diameter of the front space 43B, the second dielectric body 32, which receives a pressing force directed radially outward from the second attachment portion 23B, receives a pressing force directed radially inward from the inner peripheral surface of the front space 43B. Therefore, the second dielectric body 32 is compressed in the radial direction. As a result, the second dielectric body 32 firmly holds the outer peripheral surface of the second attachment portion 23B on the inner peripheral surface of the second through-hole portion 32A.

[0046] In the present embodiment, the second dielectric body 32 is formed with an outer diameter equal to the inner diameter of the front space 43B. Alternatively, the second dielectric body 32 may be formed with an outer diameter slightly larger than the inner diameter of the front space 43B. Even in that case, the second dielectric body 32 is compressed by receiving a pressing force directed radially inward by the inner peripheral surface of the front space 43B, and firmly holds the outer peripheral surface of the second attachment portion 23B on the inner peripheral surface of the second through-hole portion 32A.

[0047] Next, the first dielectric body 31 is attached to the first attachment portion 23A from the front. At this time, the center conductor 20 is inserted into the first through-hole portion 31A of the first dielectric body 31 from the front end side, that is, from the contact portion 22 side. In the present embodiment, since the first attachment portion 23A is formed with an outer diameter slightly larger than the inner diameter of the first through-hole portion 31A, it will be press-fitted into the first through-hole portion 31A. The first dielectric body 31 is in contact with and abuts against the first contact portion 23C-1 from the front in a state of being attached to the first attachment portion 23A. Further, in the present embodiment, the outer diameter of the first dielectric body 31 is slightly larger than the inner diameter of the front space 43B of the internal space 43, and it will be press-fitted into the front space 43B from the front. Therefore, the first dielectric body 31 receives a pressing force directed radially inward by the inner peripheral surface of the front space 43B and is compressed by receiving a pressing force directed radially outward by the outer peripheral surface of the first attachment portion 23A. As a result, the first dielectric body 31 firmly holds the outer peripheral surface of the first attachment portion 23A on the inner peripheral surface of the first through-hole portion 31A.

[0048] In a state where the center conductor 20 and the dielectric body 30 are accommodated in the internal space 43, the inner portion of the second dielectric body 32 in the radial direction is supported from the front by the second contact portion 23C-2, and the outer portion in the radial direction is supported from the rear by the support portion 44 of the support body 40 (see FIG. 3(B)). Note that it is not essential for the second dielectric body 32 to be supported from the rear by the support portion 44 at this point, and the second dielectric body 32 may be supported by the support portion 44 for the first time when the coaxial connector 1 is connected to the electronic device 2.

[0049] Next, the support body 40 is press-fitted and accommodated into the internal space 15 of the outer conductor 10 from the rear. The support body 40 is press-fitted until its front surface abuts against the rear surface of the stepped portion 16 of the outer conductor 10. As a result, as shown in FIG. 3(B), the stepped portion 16 abuts against the front surfaces of the first dielectric body 31 and the support body 40 respectively, and the first dielectric body 31 and the support body 40 are supported from the front. Further, the contact portion 22 of the center conductor 20 is accommodated in the small-diameter space 15C. By attaching the support body 40 to the outer conductor 10 in this way, the coaxial connector 1 is completed.

[0050] FIG. 4 is a partial cross-sectional view of the coaxial connector 1 and the electronic device 2 in FIG. 1(B), showing a cross-section in a plane perpendicular to the connector width direction at the position of the axis of the coaxial connector 1. As shown in FIGS. 1(A), (B) and FIG. 4, the electronic device 2 includes a metal box-shaped housing 60, a circuit board 70 built in the housing 60, and a mating center conductor 80 and a mating dielectric 90 held by a mounting portion 62 of the housing 60 to be described later. The housing 60 has a support portion 61 that supports the circuit board 70 from below, and a mounting portion 62 that forms a part of the rear wall of the housing 60 and to which the coaxial connector 1 is attached. A holding hole 62A for holding the mating center conductor 80 and the mating dielectric 90 is formed through the mounting portion 62 in the front-rear direction. Further, in the mounting portion 62, screw holes 62B for screwing the screw member 50 are formed through the mounting portion 62 in the front-rear direction on both sides of the holding hole 62A in the connector width direction (Y-axis direction).

[0051] On the mounting surface (the upper surface in FIGS. 1(A), (B)) of the circuit board 70, a signal pattern 71 extending in the front-rear direction (X-axis direction) and a ground pattern 72 spreading so as to surround the signal pattern 71 are formed. At the rear end portion of the signal pattern 71, as shown in FIG. 4, a mating connection portion 81 of the mating center conductor 80 to be described later is connected by soldering, wire bonding, or the like, and the signal pattern 71 and the mating center conductor 80 are electrically conductive. Further, in the present embodiment, the connection form between the signal pattern 71 and the mating connection portion 81 is not limited to soldering or wire bonding as described above. For example, the mating connection portion 81 may simply contact the upper surface of the signal pattern 71.

[0052] Also, as shown in FIG. 4, on the lower surface of the circuit board 70, a ground pattern 73 is formed in a range including a signal pattern 71 and a ground pattern 72 when viewed in the vertical direction. As shown in FIG. 1(A), on both sides of the signal pattern 71, a plurality of vias 74 penetrating the resin base material 75 in the vertical direction are arranged in the front-rear direction. The ground pattern 72 and the ground pattern 73 are connected by the vias 74 and are electrically conductive through the vias 74. Also, as described above, the circuit board 70 is supported from below by the support portion 61 of the metal housing 60. Therefore, when the upper surface of the support portion 61 contacts the lower surface of the ground pattern 72, the ground pattern 72 and the support portion 61 are electrically conductive.

[0053] The mating center conductor 80 extends straight in the front-rear direction and is provided penetrating the mounting portion 62 of the housing 60 as shown in FIG. 4. The mating center conductor 80 has a male mating connection portion 81 provided at the front end portion, a male mating contact portion 82 provided at the rear end portion, and a mating connection portion 83 provided between the connection portion 21 and the contact portion 22 and connecting the two.

[0054] As shown in FIG. 4, the mating connection portion 81 is in the shape of a pin protruding from the front surface of the mounting portion 62 of the housing 60 and is in contact with the upper surface of the rear end portion of the signal pattern 71 of the circuit board 70. As shown in FIG. 4, the mating contact portion 82 is in the shape of a pin protruding from the rear surface of the mounting portion 62 of the housing 60 and can be in contact with the contact portion 22 of the center conductor 20 of the coaxial connector 1. The mating connection portion 83 is disposed in the holding hole 62A of the mounting portion 62 of the housing 60 and its outer peripheral surface is held by the mating dielectric 90.

[0055] The mating dielectric 90 is in a cylindrical shape having an axis extending in the front-rear direction, is disposed in the holding hole 62A of the housing 60 and held by the mounting portion 62, and holds the outer peripheral surface of the mating connection portion 83 of the mating center conductor 80 as described above.

[0056] Next, the usage method of the coaxial connector 1 will be described. First, for the coaxial connector 1, the contact portion 22 of the center conductor 20 is aligned with the mating contact portion 82 of the mating center conductor 80, and further, the mounting hole portion 13 of the outer conductor 10 is aligned with the screw hole 62B of the mounting portion 62 of the housing 60 and is arranged on the rear surface of the mounting portion 62. The coaxial connector 1 thus arranged on the rear surface of the mounting portion 62 is attached to the mounting portion 62 as shown in Fig. 1(B) by screwing the screw member 50 into the mounting hole portion 13 and the screw hole 62B from the rear.

[0057] When the coaxial connector 1 is attached to the mounting portion 62, the contact portion 22 of the center conductor 20 receives the mating contact portion 82 of the mating center conductor 80 from the front. As a result, as shown in Fig. 4, the contact piece 22B of the contact portion 22 contacts the mating contact portion 82 in an elastically deformed state. Also, when the coaxial connector 1 is attached to the mounting portion 62, the front surface of the outer conductor 10 is pressed against the rear surface of the mounting portion 62. As a result, the outer conductor 10 can be electrically connected to the ground pattern 73 of the circuit board 70 via the mounting portion 62 and the support portion 61, and can also be electrically connected to the ground pattern 72 of the circuit board 70 via the via 74.

[0058] Also, when the coaxial connector 1 is connected to the electronic device 2, for example, due to the friction between the contact portion 22 and the mating contact portion 82, the center conductor 20 may receive a force directed rearward. At this time, the second abutting portion 23C-2 (see Fig. 3(B)) of the center conductor 20 abuts on the second dielectric 32 from the front and receives a reaction force directed forward from the second dielectric 32. Therefore, this reaction force directed forward counteracts the force directed rearward described above, and as a result, it becomes easier to maintain the center conductor 20 in the normal position in the front-rear direction.

[0059] In this embodiment, the first dielectric 31 and the second dielectric 32 are provided so as to be separated from each other in the front-rear direction. As shown in FIG. 3(B), a space 43B-1 as a part of the front space 43B is formed between the first dielectric 31 and the second dielectric 32. That is, in the range where this space 43B-1 is formed in the front-rear direction, that is, in the range of the intermediate portion 23C of the connecting portion 23 of the center conductor 20, an air layer exists between the inner peripheral surface of the support 40 and the outer peripheral surface of the intermediate portion 23C in the radial direction. Therefore, compared with the case where one dielectric that extends long in the vertical direction is provided between the outer conductor and the center conductor as in the prior art, the usable frequency band can be widened without changing the size of the connector by the amount of the existence of the air layer. As a result, good signal transmission characteristics can be ensured up to a wide band.

[0060] Further, in this embodiment, since the first dielectric 31 has a smaller dimension in the front-rear direction (connection direction) than the second dielectric 32, the dimension of the air layer formed between the first dielectric 31 and the second dielectric 32 can be increased accordingly. Therefore, the usable frequency band becomes wider, and as a result, good signal transmission characteristics can be ensured up to an even wider band.

[0061] Further, in this embodiment, since the first dielectric 31 has a lower dielectric constant than the second dielectric 32, the degree to which the usable frequency band is narrowed due to the provision of the dielectric 30 can be suppressed accordingly. Also, in this embodiment, since the second dielectric 32 has a higher hardness than the first dielectric 31, the holding force of the center conductor 20 by the second dielectric 32 can be improved. Therefore, in this embodiment, while maintaining the center conductor in a proper position well, good signal transmission characteristics can be ensured up to a wide band as much as possible.

[0062] Also, the second dielectric 32 has a higher deflection temperature under load than the first dielectric 31. Therefore, the second dielectric 32 is less likely to plastically deform even when the usage environment of the coaxial connector 1 becomes high temperature. As a result, the holding force of the center conductor 20 by the second dielectric 32 is less likely to decrease, so that the center conductor 20 is easily maintained in a proper position.

[0063] In the embodiments described above based on FIGS. 1 to 4, the contact portion 22 of the center conductor 20 had a female shape, but the shape of the contact portion can be variously deformed. FIG. 5 is a cross-sectional view of the coaxial connector 101 according to a modified example of the present embodiment, showing a cross-section in a plane perpendicular to the vertical direction (the short side direction of the base portion 111) at the position of the axis of the coaxial connector 101. In FIG. 5, the portions corresponding to the respective portions in the above-described embodiment are shown with reference numerals obtained by adding "100" to the reference numerals in the above-described embodiment.

[0064] As shown in FIG. 5, the coaxial connector 101 in this modified example is different in configuration from the coaxial connector 1 of the above-described embodiment in that the contact portion 122 of the center conductor 120 has a male shape. Specifically, the contact portion 122 has a pin shape and has a contact end portion 122A that is thinner, that is, has a smaller outer diameter dimension, than other portions of the contact portion 122, at the front end portion that protrudes forward from the front surface of the base portion 111 of the outer conductor 110. When the coaxial connector 101 is connected to an electronic device (not shown), the contact end portion 122A is inserted into a female mating contact portion provided on a mating center conductor (not shown), thereby coming into contact with the mating contact portion. Note that, in the coaxial connector 101, the configurations of the respective portions other than the above-described contact portion 122 are the same as those of the corresponding portions in the above-described embodiment, and thus the description thereof is omitted.

[0065] In the above-described embodiment and the modified example, the dielectric is directly held by the support, in other words, the dielectric is indirectly held by the outer conductor via the support, but it is not essential to provide the support. For example, the dielectric may be directly held by the outer conductor without providing the support.

[0066] Also, in the above-described embodiment and the modified example, the second dielectric is provided behind the first dielectric, but alternatively, the second dielectric may be provided in front of the first dielectric. At this time, in the center conductor, a second contact portion is provided at a position where it can abut on the second dielectric from the front.

Description of Symbols

[0067] 1 Coaxial connector 10 Outer conductor 15 Inner space 20 Central conductor 23C-2 Second contact part (contact part) 30 Dielectric 31 First dielectric 32 Second dielectric

Claims

1. A coaxial electrical connector connected to a connection target with a predetermined one direction as a connection direction, A metal outer conductor having an internal space with an axis extending in the connection direction formed to penetrate in the connection direction, A dielectric directly or indirectly held by the outer conductor within the internal space, In a coaxial electrical connector having a metal center conductor that extends in the connection direction within the internal space, is held by the dielectric, and contacts the connection target at a front end portion in the connection direction, The dielectric has a first dielectric and a second dielectric provided so as to form a space with the first dielectric at a position separated from the first dielectric in the connection direction, The first dielectric and the second dielectric hold the center conductor in the radial direction, The first dielectric has a lower dielectric constant than the second dielectric, The coaxial electrical connector, wherein the second dielectric has a higher hardness than the first dielectric.

2. The coaxial electrical connector according to claim 1, wherein the center conductor has a contact portion that can contact the second dielectric from the front in the connection direction.

3. The coaxial electrical connector according to claim 1, wherein the first dielectric is provided in front of the second dielectric in the connection direction.

4. The coaxial electrical connector according to claim 1, wherein the first dielectric has a smaller dimension in the connection direction than the second dielectric.

5. The coaxial electrical connector according to claim 1, wherein the second dielectric has a higher deflection temperature under load than the first dielectric.

6. The coaxial electrical connector according to claim 1, wherein the first dielectric is made of polytetrafluoroethylene and the second dielectric is made of polyetherimide.

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