Patent Description:
Modules such as camera modules for in-vehicle cameras have a module body housed in a case. The module body is connected to a coaxial cable via a coaxial connector attached to the case.

This coaxial connector includes a socket connected to a board that constitutes the module body housed in the case, and a plug connected to the coaxial cable. The plug and socket are connected by attaching the plug to the case or by assembling a rear case, to which the plug is attached, to a front case.

The plug includes a cylindrical shell made of a conductive metal material, an insulator that is made of an insulating resin and housed in the shell, and a central conductor that is made of a conductive metal material and held in the insulator. An insulator housing in which the socket is to be fitted is formed at one end of the shell.

The insulator is located in the axial recesses of the insulator housing, which is open on an axial end face of the shell, and forms a recessed inner wall of the insulator housing. A tip of the central conductor protrudes from the axial end face of the shell. By fitting the socket in the insulator housing, the shell is brought into contact with an outer conductor of the socket, and the central conductor is also brought into contact with a central conductor of the socket.

On the other hand, when the plug and the socket are connected, the relative position between the plug and the socket to be connected may deviate from a designed value in an axial direction, owing to the position of the board housed in the case, mounting tolerance between the plug and the case, or the like. Even in such a case, a secure connection must be made.

Therefore, a margin of a predetermined distance is provided in the insulator housing in the axial direction (connection direction) in order to absorb the positional deviation. This allows an error from the designed value in the axial direction, so that the connection between the plug and the socket is always maintained.

However, in a case in which the insulator housing is provided with the margin of the predetermined distance in the axial direction (connection direction), as described above, if the relative position between the plug and the socket is farther than the designed value, an air layer with a dielectric constant lower than that of the resin occurs between an axial end face of the insulator and an end face of the socket, which may cause change in matched impedance.

Therefore, for this type of coaxial connectors, coaxial connectors are developed which include a movable insulator housed so as to be slidable with respect to the central conductor in the insulator housing and a metal elastic member, such as a coil spring or a leaf spring, which is interposed between the movable insulator and a fixed insulator held in the shell or between the movable insulator and an inner wall of the shell and which biases the movable insulator to the side of the socket, so as to make an end face of the movable insulator always in contact with the end face of the socket. (See, for example, Patent Literature <NUM>). Further, <CIT> describes an electrical contact device for electrically connecting a first component and a second component. The electrical contact device includes an outer conductor, at least one inner conductor disposed within the outer conductor, and a first elastic member disposed between the outer conductor and the at least one inner conductor. The outer conductor and the at least one inner conductor are respectively connected to or contactable with the first component and the second component. The axial extension of the at least one inner conductor and the at least one outer conductor is respectively changeable. The first elastic element is made of an electrically insulating material and is fixed to the outer conductor.

However, in the technology as described above, the placement of the metal elastic member, such as the coil spring or the leaf spring, around the central conductor could interfere with impedance matching.

In view of these conventional problems, an object of the present invention is to provide a coaxial connector that can suitably bias a movable insulator to the side of a socket and maintain matched impedance.

To solve the above-described conventional problems, a first aspect of the present invention is a coaxial connector, the coaxial connector including a plug in which a socket is fitted at one end. The plug includes: a shell that is made of a conductive material and has an insulator housing open to the one end; an outer conductor that is made of a conductive material and is held inside the insulator housing; a central conductor that is made of a conductive material and is located inside the shell; a movable insulator that is fitted in the central conductor so as to be slidable with respect to the central conductor and is housed in the insulator housing so as to be movable in an axial direction; and a biasing rubber member that is interposed between a partition disposed in the recesses of the insulator housing and the movable insulator or between a fixed insulator fixed in the shell and the movable insulator. The biasing rubber member includes: a pair of bearing plates that are opposite to each other with a space in between; and a plurality of elastic pillars that connect between both the bearing plates. When the socket is connected to the plug, the movable insulator is pushed in by a pushing force from the socket, so that the elastic pillars are bent in an arc shape.

In a second aspect of the present invention , in addition to the configuration of the first aspect, the movable insulator includes, on an outer face, a guide groove into which a guide protrusion protruding to an inner face of the insulator housing is inserted. The movable insulator slides in the insulator housing in the axial direction by being guided by the guide protrusion. The biasing rubber member includes, along side edges of the bearing plates, guide recesses into which the guide protrusion is inserted. The elastic pillars are arranged on the side edges of the guide recesses in such a manner that a side toward the center of the curvature faces the guide protrusion.

In a third aspect of the invention, in addition to the configuration according to the first or second aspect, the elastic pillars each include a plate-shaped pillar body disposed on the side toward the center of the curvature, and a reinforcing protrusion protruding outside the pillar body relative to the curvature.

In a fourth aspect of the present invention, in addition to the configuration of the third aspect, the width of the pillar body is twice or more the width of the reinforcing protrusion in a protruding direction.

In a fifth aspect of the present invention, in addition to the configuration of any one of the first to fourth aspects, the movable insulator is formed with a conductor insertion hole into which the central conductor is inserted, and a slide hole which is communicated with the conductor insertion hole and into which the fixed insulator fixed in the shell is inserted so as to be slidable.

The coaxial connector according to the aspect(s) of the present invention, by having the configuration of the first aspect, can suitably bias the movable insulator to the side of the socket without forming an air layer between the movable insulator and the socket. In addition, no metal material is placed around the central conductor, thus allowing matched impedance to be maintained.

Also, in the aspect(s) of the present invention, by having the configuration of the second aspect, the curvature of the elastic pillars can be suitably controlled, which allows a stable floating state to be maintained.

Furthermore, in the aspect(s) of the present invention, by having the configuration of the third and fourth aspects, a constant biasing force can be exerted and the curvature can be suitably controlled.

Furthermore, in the aspect(s) of the present invention, by having the configuration of the fifth aspect, the central conductor is covered with a resin material, thus allowing impedance matching to be maintained.

Next, an embodiment of a coaxial connector with a floating mechanism according to the present invention will be described on the basis of an example illustrated in <FIG>. In the drawings, the reference numeral <NUM> indicates the coaxial connector with a floating mechanism.

In the coaxial connector with a floating mechanism (hereinafter referred to as coaxial connector) <NUM>, as illustrated in <FIG>, a socket <NUM> is fitted in one end of a plug <NUM> connected to a coaxial cable or the like, so that the plug <NUM> and the socket <NUM> are electrically connected to each other.

As illustrated in <FIG> and <FIG>, the plug <NUM> includes a shell <NUM> containing an insulator housing <NUM> that is open at one end, an external conductor <NUM> held inside the insulator housing <NUM>, a central conductor <NUM> disposed inside the shell <NUM>, a movable insulator <NUM> housed in the insulator housing <NUM> as to be movable in an axial direction, and a biasing rubber member <NUM> that biases the movable insulator <NUM> towards the socket <NUM>.

As illustrated in <FIG>, the shell <NUM> is formed of a conductive metal material in a deformed cylindrical shape as a single body. The shell <NUM> has a round-hole-shaped cable connection part <NUM> and the rectangle-hole-shaped insulator housing <NUM> that are formed continuously in the axial direction through a partition <NUM>.

The partition <NUM> is formed in the shape of a plate orthogonal to the axial direction, and has a round-hole-shaped insulator insertion hole <NUM> formed in the center.

In the cable connection part <NUM>, a fixed insulator <NUM> holding the pin-shaped central conductor <NUM> made of a conductive metal material, a cylindrical intermediate rubber member <NUM>, and a bottomed cylindrical-shaped cable-side insulator <NUM> made of an insulating resin are sequentially fitted. The fixed insulator <NUM>, the intermediate rubber member <NUM>, and the cable-side insulator <NUM> hold the central conductor <NUM> concentrically at the center of the shell <NUM>.

The fixed insulator <NUM> is formed of an insulating resin as a single body. The fixed insulator <NUM> includes a cylindrical protrusion <NUM> and a flange <NUM> protruding from one end of the protrusion <NUM>. The protrusion <NUM> protrudes to the insulator housing <NUM> through the insulator insertion hole <NUM> of the partition <NUM>. The flange <NUM> is configured to be in contact with the partition <NUM>.

In the fixed insulator <NUM>, the central conductor <NUM> is held in a penetration state. The flange <NUM> is pressed by the intermediate rubber member <NUM> and the cable-side insulator <NUM> to the side of the partition <NUM>, and is then fixed in the shell <NUM> in a non-movable manner.

The insulator housing <NUM> is formed in the shape of a rectangular hole with a recessed side closed by the partition <NUM> and the other end open. As illustrated in <FIG>, the biasing rubber member <NUM> and the movable insulator <NUM> are housed in the insulator housing <NUM> from the side of the opening, and the external conductor <NUM> is fitted in and connected to the opening.

Guide protrusions <NUM>, <NUM> protrude on a pair of inner surfaces of the insulator housing <NUM> that are opposite to each other. The movable insulator <NUM> can slide in the insulator housing <NUM> in the axial direction by being guided by both the guide protrusions <NUM>, <NUM>.

The guide protrusions <NUM>, <NUM> are formed in a rectangular parallelepiped shape long in the axial direction, with flat side faces 18a, 18a on both sides. The guide protrusions <NUM>, <NUM> are inserted into guide grooves <NUM>, <NUM> formed on side faces of the movable insulator <NUM> to guide the movable insulator <NUM> in the axial direction.

The guide protrusions <NUM>, <NUM> are formed to be longer at least than the height of the biasing rubber member <NUM> in the axial direction, and have the side faces 18a, 18a that are always positioned on a side A which is a side toward the center of the curvature of elastic pillars <NUM>, <NUM> ···, which will be described later.

Note that, the curvature refers to a direction to which, with respect to each elastic pillar <NUM>, the elastic pillar <NUM> is bent into an arc shape and expands under an axial compression force. The side toward the center of the curvature refers to a side with the center of the expanding arc (a side indicated by arrows A in <FIG>, <FIG>). An outside of the curvature refers to a side of expansion of the expanding arc (sides indicated by arrows B in <FIG>, <FIG>).

As illustrated in <FIG>, the movable insulator <NUM> is formed of an insulating resin in a rectangular parallelepiped shape, and has an outwardly protruding flange <NUM> at one end (on the side of the partition <NUM>). The movable insulator <NUM> is inserted into the external conductor <NUM> so as to be slidable, and the flange <NUM> prevents the movable insulator <NUM> from slipping out of the outer conductor <NUM>.

In this movable insulator <NUM>, a conductor insertion hole <NUM> through which the central conductor <NUM> is inserted is formed by penetrating the center, and a slide hole <NUM> is formed on the side of the partition <NUM> relative to the conductor insertion hole <NUM>. The protrusion <NUM> of the fixed insulator <NUM>, which protrudes from the partition <NUM> into the insulator housing <NUM>, is inserted into the slide hole <NUM> so as to be slidable. The movable insulator <NUM> is fitted in the central conductor <NUM> in the axial direction so as to be slidable.

The axially long guide grooves <NUM>, <NUM> matched with the guide protrusions <NUM>, <NUM> are formed on side faces of the movable insulator <NUM>. The movable insulator <NUM> can move in the axial direction in the insulator housing <NUM> along the guide protrusions <NUM>, <NUM> inserted into the guide grooves <NUM>, <NUM>.

As illustrated in <FIG> and <FIG>, the biasing rubber member <NUM> is formed of an elastic rubber material as a single body. The biasing rubber member <NUM> includes a pair of rectangular bearing plates <NUM>, <NUM> that are opposite to each other in the axial direction separated by a predetermined distance, and the plurality of elastic pillars <NUM>, <NUM> ··· that connect the bearing plates <NUM>, <NUM>. The bearing plates <NUM> are made to be in contact with the partition <NUM> and an end face of the movable insulator <NUM>, respectively. The biasing rubber member <NUM> biases the movable insulator <NUM> to the side of the socket <NUM> by exerting a reaction force on the partition <NUM>.

The bearing plates <NUM>, <NUM> are formed in the shape of a rectangular plate that matches with the shape of the cross section of the insulator housing <NUM>. The bearing plates <NUM>, <NUM> each have an insulator through hole <NUM> in the center through which the protrusion <NUM> of the fixed insulator <NUM> is inserted, and are made to be in surface contact with the partition <NUM> and the end face of the movable insulator <NUM>, respectively.

Along the side edges of the bearing plates <NUM>, <NUM>, guide recesses <NUM>, <NUM> through which the guide protrusions <NUM>, <NUM> are inserted are formed. Both the bearing plates <NUM>, <NUM> are guided by the guide protrusions <NUM>, <NUM> so as to be movable relative to each other in the axial direction.

The elastic pillars <NUM>, <NUM> ··· each include a plate-shaped pillar body 20a that is disposed on the side A toward the center of the curvature and is long in the connection direction of the bearing plates <NUM>, <NUM>, and a reinforcing protrusion 20b that protrudes outside the pillar body 20a relative to curvature. The pillar body 20a and the reinforcing protrusion 20b are formed into a pillar shape continuous in the connection direction of the bearing plates <NUM>, <NUM>, with the shape of the letter L or T as the cross section.

Each of the elastic pillars <NUM>, <NUM> ··· is arranged in such a manner that a surface of the pillar body 20a (a surface on the opposite side of the reinforcing protrusion 20b) is coplanar to an inner face of the guide recess <NUM>. The elastic pillars <NUM>, <NUM> connect between the side edges of the guide recesses <NUM>, <NUM> of both the bearing plates <NUM>, <NUM> in such a manner that the side A toward the center of the curvature faces the guide protrusions <NUM>, <NUM>.

Note that, since the elastic pillars <NUM>, <NUM> ··· are arranged on the side edges of the guide recesses <NUM>, <NUM>, the guide protrusions <NUM>, <NUM> are always arranged on the side A toward the center of the curvature. Thus, each of the elastic pillars <NUM>, <NUM> ··· is prevented from being bent to the side of the guide protrusions <NUM>, <NUM>, and is bent smoothly in an arc shape with the side of the reinforcing protrusion 20b being directed to the outside B of the curvature.

Note that, in order to obtain smooth bending and a predetermined reaction force, it is desirable that the width w1 of the pillar body 20a be twice or more the width w2 of the reinforcing protrusion 20b in a protruding direction.

The external conductor <NUM> is formed into a rectangular cylindrical shape by punching and bending a conductive plate material. On the side faces of the external conductor <NUM>, leaf spring-shaped contacts <NUM>, <NUM> ··· for establishing connection to an external conductor <NUM> of the socket <NUM> are formed by lancing.

The external conductor <NUM> has outwardly protruding engagement pieces <NUM>, <NUM> formed on outer faces at one end. The external conductor <NUM> is fixed and connected to the inside of the insulator housing <NUM> by engagement of the engagement pieces <NUM>, <NUM> with inner faces of the insulator housing <NUM>. The movable insulator <NUM> is inserted into the inside of the external conductor <NUM> so as to be movable, and the flange <NUM> comes into contact with the external conductor <NUM> to prevent the movable insulator <NUM> from slipping out of the external conductor <NUM>.

In this coaxial connector <NUM>, when the socket <NUM> is fitted in the external conductor <NUM>, the socket <NUM> pushes the movable insulator <NUM> to the recesses, and the contacts <NUM>, <NUM> ··· of the external conductor <NUM> come into contact with the socket external conductor <NUM>. A tip of the central conductor <NUM> is inserted into a socket housing <NUM> and comes into contact with a socket contact <NUM> to establish an electric connection.

When the movable insulator <NUM> is pushed to the recesses further, the bearing plate <NUM> on the side of the movable insulator <NUM> is pressed against the bearing plate <NUM> that is in contact with the partition <NUM>, and the elastic pillars <NUM>, <NUM> ···, which connect between both the bearing plates <NUM>, are bent in an arc shape. Thereby, the biasing rubber member <NUM> biases the movable insulator <NUM> to the side of the socket <NUM> by exerting a reaction force on the partition <NUM>.

Therefore, even in a case in which the relative position between the plug <NUM> and the socket <NUM> to be connected deviates from a designed value in the axial direction, owing to the position of a board housed in the case, mounting tolerance between the plug <NUM> and the case, or the like, a tip end face of the movable insulator <NUM> always remains in contact with a connection end face of the socket <NUM> without the occurrence of a gap (air layer) between the movable insulator <NUM> and the socket <NUM>, thus allowing impedance matching to be maintained.

Specifically, in a case in which the distance between the plug <NUM> and the socket <NUM> is larger than a designed value, the movable insulator <NUM> is pushed to the side of the socket <NUM> until the elastic pillars <NUM>, <NUM> ··· are extended as illustrated in <FIG>. In a case in which the distance between the plug <NUM> and the socket <NUM> is lesser than the designed value, the elastic pillars <NUM>, <NUM> ··· are bent, and by the reaction force exerted thereby, the movable insulator <NUM> is pushed to the side of the socket <NUM>, as illustrated in <FIG>.

In this case, the bearing plates <NUM>, <NUM> of the biasing rubber member <NUM> are formed in the shape of plates and thus are in surface contact with the partition <NUM> and the end face of the movable insulator <NUM>, respectively, so that the compression force associated with the pushing of the movable insulator <NUM> is evenly distributed to the individual elastic pillars <NUM>, <NUM> ··· and the elastic pillars <NUM>, <NUM> ··· are suitably bent.

The biasing rubber member <NUM> is designed to be bent in a stable manner, because the guide protrusions <NUM>, <NUM> are arranged on the side A toward the center of the curvature of each of the elastic pillars <NUM>, <NUM> ··· and the direction of curvature of each of the elastic pillars <NUM>, <NUM> ··· is restricted, as illustrated in <FIG>.

In addition, since each of the elastic pillars <NUM>, <NUM> ··· has the reinforcing protrusion 20b protruding to the outside B of the curvature of the pillar body 20a, and the width w1 of the pillar body 20a is twice or more the width w2 of the reinforcing protrusion 20b in the protruding direction, the biasing rubber member <NUM> can bias the movable insulator <NUM> to the side of the socket <NUM> with a suitable biasing force by obtaining a sufficient reaction force to accompany the bending.

In the above-described embodiment, a case in which the partition <NUM> of the shell <NUM> is the object of the reaction force exerted by the biasing rubber member <NUM> is described, but the reaction force may be exerted on the fixed insulator <NUM>.

Claim 1:
A coaxial connector (<NUM>), the coaxial connector (<NUM>) comprising a plug (<NUM>) in which a socket (<NUM>) is fitted at one end of the plug (<NUM>), wherein
the plug (<NUM>) includes:
a shell (<NUM>) that is made of a conductive material and has an insulator housing (<NUM>) open to the one end;
an outer conductor that is made of a conductive material and is held inside the insulator housing (<NUM>);
a central conductor (<NUM>) that is made of a conductive material and is located inside the shell (<NUM>);
a movable insulator (<NUM>) that is fitted in the central conductor (<NUM>) so as to be slidable with respect to the central conductor (<NUM>) and is housed in the insulator housing (<NUM>) so as to be movable in an axial direction; and
a biasing rubber member (<NUM>) that is interposed between a partition (<NUM>) disposed in the recesses of the insulator housing (<NUM>) and the movable insulator (<NUM>) or between a fixed insulator (<NUM>) fixed in the shell (<NUM>) and the movable insulator (<NUM>), the biasing rubber member (<NUM>) including a pair of bearing plate (<NUM>)s that are opposite to each other with a space in between, and a plurality of elastic pillars that connect between both the bearing plate (<NUM>)s, and
when the socket (<NUM>) is connected to the plug (<NUM>), the movable insulator (<NUM>) is pushed in by a pushing force from the socket (<NUM>), so that the elastic pillars are bent in an arc shape.