Cable connection structure used in vehicle antenna device

To provide a cable connection structure used in a vehicle antenna device, capable of being reduced in size, easy to assemble, and having required tensile strength. The cable connection structure includes a connection terminal 10, a circuit board 20, a base plate 30, a positioning abutting part 40, and a cable clamp 50. The connection terminal 10 is attached to a braided wire 3 of a coaxial cable 1. The circuit board 20 has a signal line connection hole 21 and a ground line connection hole 22. The base plate 30 has a cable insertion hole 31. The positioning abutting part 40 is used for determining the position of the circuit board 20 on the base plate 30. The cable clamp 50 grasps a protective outer cover 4 of the coaxial cable 1, holds a core wire 2 such that the core wire 2 is exposed at a predetermined height position, and holds a connection terminal 10 such that the connection terminal 10 is exposed at a predetermined height position.

TECHNICAL FIELD

The present invention relates to a cable connection structure used in a vehicle antenna device, and more particularly to a cable connection structure suitable for an antenna having a low-height structure or compact structure, such as a low-profile antenna device.

BACKGROUND ART

A vehicle antenna device is installed on a vehicle roof or the like. A signal cable connected to a tuner or the like provided in a vehicle is connected to a circuit board of the vehicle antenna device through an installation hole formed in the vehicle roof. The signal cable is connected to the antenna device using a cable attachment structure disclosed in, e.g., Patent Document 1. In the cable connection structure disclosed in Patent Document 1, a metal clamp fixed with a signal cable by clamping in advance is inserted through a through hole formed in a base plate to be pulled above the base plate, turned by a predetermined angle, and then pulled downward to be fixed to a groove formed in the base plate. Then, the signal cable fixed to the metal clamp is soldered to the circuit board.

CITATION LIST

Patent Document

Patent Document 1: Japanese Patent Application Kokai Publication No. 2002-329559

DISCLOSURE OF THE INVENTION

Problems to be Solved by the Invention

However, in the cable connection structure like the one disclosed in Patent Document 1, it is necessary to fix the metal clamp to the signal cable by clamping in advance and to provide a through hole for insertion of the metal clamp. Therefore, it is necessary to provide the through hole for inserting the metal clamp larger than that for insertion of the signal cable, and this hinders miniaturization. Further, since both the metal clamp and the base plate are made of metal, when the press-fitting dimension for press-fitting the metal clamp in the groove of the base plate deviates, even if only slightly, from a designed value, a problem arises with assembly. Further, when backlash occurs due to allowance, it is difficult to achieve position alignment between the metal clamp and the through hole formed in the circuit board, whereby easily assembly is difficult. Furthermore, in this structure, since the metal clamp is fixed in the groove formed in the base plate by pulling the signal cable downward, when upward pushing force occurs in the signal cable, the metal clamp moves, whereby the problem such as the breaking of the signal wire occurs. Thus, a cable connection structure has been desired capable of being reduced in size, easy to assemble and having required tensile strength.

In view of the above situation, the present invention has been made and the object thereof is to provide a cable connection structure used in a vehicle antenna device, capable of being reduced in size, easy to assemble and having required tensile strength.

Means for Solving the Problems

In order to achieve the above object of the present invention, a cable connection structure according to the present invention used in a vehicle antenna device may comprise: a connection terminal attached to a braided wire of a coaxial cable having a core wire as a signal line, the braded wire as a ground line, and a protective outer cover constituting an outermost sheath; a circuit board having a signal line connection hole for the core wire of the coaxial cable and a ground line connection hole for the connection terminal; a base plate on which the circuit board is placed, having a cable insertion hole through which the coaxial cable is inserted; a positioning abutting part for determining the position of the circuit board on the base plate; and a cable clamp grasping the protective outer cover of the coaxial cable, holding the core wire so as to be exposed at a predetermined height position toward the circuit board side for being electrically connected to the signal line connection hole of the circuit board, and holding the connection terminal so as to be exposed at a predetermined height position toward the circuit board side for being electrically connected to the ground line connection hole of the circuit board.

The cable clamp may be disposed between the circuit board and the base plate and be fitted into the cable insertion hole of the base plate from a side on which the circuit board is placed.

The positioning abutting part may be disposed on the base plate.

The connection terminal may function also as the positioning abutting part by being held through the cable clamp.

The connection terminal may have a blade-shaped part vertically extending with respect to a surface direction of the circuit board, and the ground line connection hole of the circuit board may be formed into a slit shape so as to correspond to the blade-shaped part of the connection terminal.

The ground line connection hole of the circuit board may be formed into a slit-like hole elongated parallel to a direction away from the positioning abutting part.

A tip of the blade-shaped part of the connection terminal ma be chamfered.

The connection terminal may be crimped to the braided wire of the coaxial cable.

When the circuit board is disposed to be parallel to the base plate from a state where the circuit board is inclined with one end thereof abutting on the positioning abutting part and with the other end thereof lifted upward during assembling, the cable clamp may hold the core wire and the connection terminal so as to have a height relationship that the connection terminal is inserted into the ground line connection hole before the core wire of the coaxial cable is inserted into the signal line connection hole.

The cable clamp may hold the connection terminal at a side close to the positioning abutting part and the core wire at a side far from the positioning abutting part.

The circuit board may have the ground line connection hole at a side close to the positioning abutting part and the signal line connection hole at a side far from the positioning abutting part.

The cable clamp may have a cable come-off preventing projection that projects toward an outer peripheral surface of the protective outer cover of the coaxial cable so as to prevent the coaxial cable from coming off from the cable clamp.

The cable clamp may have a cable clamp come-off preventing projection that projects toward an inner peripheral surface of the cable insertion hole so as to prevent the cable clamp from coming off from the cable insertion hole of the base plate.

The cable clamp may be formed asymmetric so as to fix a shaft rotation direction thereof fitted into the cable insertion hole to be predetermined direction.

Advantageous Effects of the Invention

The cable connection structure according to the present invention used in a vehicle antenna device has advantages in that it is capable of being reduced in size, easy to assemble and has required tensile strength.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, an embodiment for practicing the present invention will be described with reference to the accompanying drawings.FIG. 1is a schematic exploded perspective view for explaining a cable connection structure according to the present invention used in a vehicle antenna device.FIG. 2is a schematic perspective view for explaining an assembled state of the cable connection structure according to the present invention used in a vehicle antenna device.FIG. 3is a schematic cross-sectional view, as viewed from the front, for explaining the assembled state of the cable connection structure according to the present invention used in a vehicle antenna device. In the drawings, the same reference numerals denote the same parts. As illustrated, the cable connection structure according to the present invention used in a vehicle antenna device mainly includes a connection terminal10, a circuit board20, a base plate30, a positioning abutting part40, and a cable clamp50. The cable connection structure according to the present invention is used for connecting a vehicle antenna device placed on a vehicle roof and a coaxial cable.

The connection terminal10is provided to a coaxial cable1. The coaxial cable1includes a core wire2which is a signal line, a braided wire3which is a ground line, and a protective outer cover4constituting the outermost sheath thereof. The coaxial cable1may be a typical one. In the illustrated example, two coaxial cables1are used and one power cable5is used. However, the number of the coaxial cables1is not limited to this, and only one coaxial cable or more cables may be used in the present invention.

The connection terminal10is attached to the braided wire3of the coaxial cable1. To the braided wire3, the connection terminal10may be attached by crimping. Also, this may be attached by soldering. In either case, the connection terminal10and the braided wire3are electrically connected to each other. Further, in the illustrated example, the connection terminal10is attached to the braided wire3after the coaxial cable1is inserted through a cable insertion hole31formed in the base plate30to be described later. Thus, there is no problem if the connection terminal10has a diameter larger than the diameter of the cable insertion hole31. Further, in the example, the connection terminal10has a blade-shaped part11vertically extending with respect to the surface direction of the circuit board20. More specifically, the connection terminal10includes a crimping part12attached to the braided wire3and a blade-shaped part11formed using the same material as the crimping part12. The blade-shaped part11extends vertically with respect to the surface direction of the circuit board20. In the illustrated example, two connection terminals10are provided so as to correspond to the number of the coaxial cables1. The connection terminal10is attached to the braided wire3of the coaxial cable1and thus serves as a ground. Therefore, even when a plurality of coaxial cables1are used as in the illustrated example, the blade-shaped part11and the crimping part12of each of the connection terminals10can be formed integrally using the same material.

The circuit board20has circuit elements required for a vehicle antenna device, an amplifier circuit and the like placed thereon. In the cable connection structure according to the present invention used in a vehicle antenna device, the circuit board20includes a signal line connection hole21and a ground line connection hole22. The core wire2of the coaxial cable1is inserted into the signal line connection hole21and electrically connected thereto by soldering or the like. The connection terminal10attached to the braided wire3of the coaxial cable1is inserted into the ground line connection hole22and electrically connected thereto by soldering or the like. Since the connection terminal10has the blade shaped part11, the illustrated ground line connection hole22is formed into a slit shaped hole corresponding thereto.

The base plate30has the circuit board20placed thereon. The cable insertion hole31thorough which the coaxial cable1is to be inserted is provided in the base plate30. The cable insertion hole31may be of any size as long as the coaxial cable1or a power cable5can pass therethrough. The base plate30is fixed to, for example, a vehicle roof. Specifically, the base plate30may be a so-called resin base formed of an insulating material such as resin or a so-called metal base formed of a conducting material such as metal. Alternatively, the base plate30may be a composite base of resin and metal. For example, a threaded boss is provided on the back surface side of the base plate30, is inserted into a hole formed in the vehicle roof, and is fixed to the vehicle roof by using a nut from the vehicle interior side so as to interpose the roof. The cable insertion hole31may be provided at a position corresponding to the threaded boss. Further, the base plate30may be constituted to be covered with an antenna cover having an interior space in which, for example, an antenna element, a circuit board and the like are accommodated.

The positioning abutting part40is provided for determining the position of the circuit board20on the base plate30. When the circuit board20is assembled onto the base plate30, the circuit board20is disposed to be parallel to the base plate30from a state where the circuit board20is inclined with one end thereof abutting on the positioning abutting part40and with the other end thereof lifted upward. By this assembly, the circuit board20is accurately disposed at a predetermined position on the base plate30. In the illustrated example, the positioning abutting part40is constituted by two block-shaped bodies which are disposed on the base plate30so as to abut against the corners of the circuit board20. However, the present invention is not limited to this, and the positioning abutting part40may have any shape as long as the relative positions of the circuit board20and the base plate30can be accurately determined. For example, a recessed part may be formed in the circuit board20and a protruding part fitted into the recessed part may be formed on the base plate30. Further, a protruding part abutting against the entire length of one side of the circuit board20may be formed on the base plate30.

The cable clamp50holds the connection terminal10. Specifically, for example, a groove is provided into which the connection terminal10crimped to the braided wire3of the coaxial cable1is fitted. The cable clamp50may have any holding structure as long as the connection terminal10is pinched and fixed therein. Further, the cable clamp50grasps the protective outer cover4of the coaxial cable1. That is, the cable clamp50grasps the protective outer cover4in such a way as to pinch the coaxial cable1. Further, the cable clamp50holds the core wire2such that the core wire2is exposed to the circuit board20side at a predetermined height position. Since the cable clamp50is configured to hold the connection terminal10and the core wire2, it should be made of an insulating material so as to prevent electrical connection therebetween.

As illustrated inFIG. 3, a core wire holding part55is provided, that holds the core wire2at a part of the cable clamp50near the circuit board20. By doing so, the core wire2is fixed, whereby the core wire2can electrically be connected to the signal line connection hole21of the circuit board20. In the illustrated example, the cable clamp50is illustrated as having such a structure as to pinch the connection terminal10from both sides after the coaxial cable1is attached thereto. This allows the assembly to be facilitated. The cable clamp50holds the connection terminal10such that the connection terminal10is exposed to the circuit board20side at a predetermined height position. This allows the connection terminal10to be electrically connected to the ground line connection hole22of the circuit board20. Further, a cable come-off preventing projection51may be provided to the cable clamp50, that projects toward an outer peripheral surface of the protective outer cover of the coaxial cable1so as to prevent the coaxial cable1from coming off from the cable clamp50.

As illustrated inFIGS. 2 and 3, the cable clamp50is disposed between the circuit board20and the base plate30. That is, the cable clamp50has a height dimension corresponding to the distance between the circuit board20and the base plate30so that it is sandwiched therebetween. Further, the cable clamp50is configured to be fitted to the cable insertion hole31of the base plate30from a side on which the circuit board20is placed. That is, the cable insertion hole31of the base plate30has a recessed part so as to allow the cable clamp50to be fitted therearound. Specifically, the cable insertion hole31may be configured to have a diameter larger than the diameter of the coaxial cable1at the side thereof on which the circuit board20is placed and to be fitted with the cable clamp50while holding the coaxial cable1. Since the cable clamp50is fitted into the cable insertion hole31while grasping the protective outer cover4of the coaxial cable1, the coaxial cable1can be gripped more firmly. As a result, sufficient tensile strength can be achieved.

Further, the cable clamp50may be formed asymmetric so as to fix a shaft rotation direction thereof fitted into the cable insertion hole31of the base plate30to be a predetermined direction. For example, as illustrated, a configuration may be possible in which a projecting part is formed to project from the side surface of the cable clamp50, and a recessed part to be fitted to the projecting part is formed in the side surface of the cable insertion hole31. With this configuration, the positional relationship between the core wire2and the connection terminal10can be fixed, whereby preventing error in the fitting direction of the cable clamp50. Additionally, for example, when a plurality of coaxial cables1are to be used, the coaxial cables can be oriented correctly.

Further, as illustrated inFIG. 3, a cable clamp come-off preventing projection52may be provided to the cable clamp50, that projects toward an inner peripheral surface of the cable insertion hole31so as to prevent the cable clamp50from coming off from the cable insertion hole31of the base plate30. With this configuration, even when an upward pushing force acts on the coaxial cable1, a load applied onto the circuit board20side can be further reduced.

In the illustrated example, the cable clamp50is disposed between the circuit board20and the base plate30and is fitted into the cable insertion hole31from a side on which the circuit board20is placed. With this configuration, since the position of the cable clamp50firmly grasping the coaxial cable is fixed, even if the coaxial cable is pushed upward, disconnection will not occur. The present invention is not limited to the above example in which the cable clamp is disposed between the circuit board and the base plate, and the cable clamp50grasping the coaxial cable in a pinching manner may be fitted into the cable insertion hole31of the base plate30from a side opposite to the side at which the circuit board is placed. In this case, in order to prevent come-off of the cable clamp when a pulling-down force acts on the coaxial cable, an engagement part or the like may be appropriately provided so as to fix the cable clamp in the cable insertion hole of the base plate.

In the cable connection structure according to the present invention used in a vehicle antenna device, since the cable clamp50is disposed between the circuit board20and the base plate30, a cable can be connected directly from just below the circuit board20in the shortest route. Therefore, a space on the base plate30can be efficiently used, which in turn allows miniaturization of a vehicle antenna device. Also, since the positional relationship between the core wire2and the connection terminal10is fixed, the core wire2can easily be connected to the connection hole of the circuit board20.

Next, the detailed assembly is described usingFIG. 4.FIG. 4is a schematic cross-sectional view, as viewed from the side, for explaining a state where the cable connection structure according to the present invention used in a vehicle antenna device is being assembled. InFIG. 4, the same reference numerals as those inFIGS. 1 to 3denote the same parts as those inFIGS. 1 to 3. As illustrated, the connection terminal10is crimped to the braided wire3of the coaxial cable1first, attached with the cable clamp50, and then is fitted into the cable insertion hole31of the base plate30. After that, the circuit board20is assembled from its inclined state with one end thereof abutting against the positioning abutting part40and with the other end thereof lifted upward, and then the circuit board20is disposed so as to be parallel to the base plate30. The cable clamp50is configured to hold the core wire2and the connection terminal10in such a height relationship that the connection terminal10is inserted into the ground line connection hole22before the core wire2of the coaxial cable1is inserted into the signal line connection hole21. For example, the cable clamp50may hold the connection terminal10at a side close to the positioning abutting part40and the core wire2at a side far from the positioning abutting part40. Correspondingly, the circuit board20may have the ground line connection hole22at a side close to the positioning abutting part40and the signal line connection hole21at a side far from the positioning abutting part40. As a result, the connection terminal10is inserted into the ground line connection hole22first, and then the core wire2is inserted into the signal line connection hole21. Thus, it is possible to reduce a risk that the core wire2is bent by the circuit board20at the time of assembly.

As described above, the cable connection structure according to the present invention used in a vehicle antenna device is easy to assemble, making it possible to reduce assembly failures.

As illustrated inFIGS. 1, 2, and the like, the ground line connection hole22of the circuit board20may be formed into a slit-like hole elongated parallel to a direction away from the positioning abutting part40. Thus, when the circuit board20is assembled to be parallel to the base plate30from a state where the circuit board20is inclined with one end thereof abutting on the positioning abutting part40and with the other end thereof lifted upward, the blade-shaped part11of the connection terminal10is easily inserted into the slit-like ground line connection hole22from the corner thereof. In this case, when the tip of the blade-shaped part11is chamfered, the blade-shaped part11is inserted into the ground line connection hole22more smoothly as illustrated inFIG. 4. Although the opposite corners are chamfered in the illustrated example, the present invention is not limited to this, and a corner of only one side, e.g., only the corner on the positioning abutting part40side may be chamfered.

Next, another example of the cable connection structure according to the present invention used in a vehicle antenna device is described.FIG. 5is a schematic cross-sectional view, as viewed from the side, for explaining another example of the state where the cable connection structure according to the present invention used in a vehicle antenna device is being assembled. InFIG. 5, the same reference numerals as those inFIGS. 1 to 4denote the same parts as those inFIGS. 1 to 4. As illustrated, the cable clamp50may hold the core wire2at a side close to the positioning abutting part40and the connection terminal10at a side far from the positioning abutting part40. In this case, the top end of the blade-shaped part11of the connection terminal10may be set higher in height position than the top end of the core wire2. Even in such a configuration, the connection terminal10is inserted into the ground line connection hole22first, and then the core wire2is inserted into the signal line connection hole21.

Further,FIG. 6is a schematic cross-sectional view, as viewed from the side, for explaining a still another example of the state where the cable connection structure according to the present invention used in a vehicle antenna device is being assembled. InFIG. 6, the same reference numerals as those inFIGS. 1 to 5denote the same parts as those inFIGS. 1 to 5. In this illustrated example, the connection terminal10is configured to function also as the positioning abutting part40. As illustrated, the top end of the blade-shaped part11of the connection terminal10is set higher in height position than the top end of the core wire2. A projection is formed to project from the lower portion of the blade-shaped part11so as to serve as the positioning abutting part40. In this configuration, the blade-shaped part11is hooked into the ground line connection hole22of the circuit board20to position the circuit board20. At this time, the positioning abutting part40functions to prevent the circuit board20from going too deep to contact the core wire2before the circuit board20gets in position. Thereafter, the circuit board20is assembled so as to be parallel to the base plate30.

In the above illustrated examples, the circuit board and the base plate are disposed parallel to each other; however, the present invention is not limited to this.FIG. 7is a schematic cross-sectional view, as viewed from the front, for explaining an example in which the cable connection structure according to the present invention used in a vehicle antenna device is applied to a vertical board. InFIG. 7, the same reference numerals as those inFIGS. 1 to 6denote the same parts as those inFIGS. 1 to 6. As illustrated, in this example, the circuit board20is disposed vertical to the base plate30. In this case, the coaxial cable1may be bent by 90 degrees in the cable clamp50. Further, in the illustrated example, the corner at which the base plate30and the cable clamp50are fitted to each other functions as the positioning abutting part40and, in this case, as denoted by dashed line inFIG. 7, first the front end of the circuit board20is inserted obliquely into the corner, and then the circuit board20is arranged so as to take a upright posture with respect to the base plate30.

The cable connection structure according to the present invention used in a vehicle antenna device is not limited to the above illustrative examples but may be variously modified without departing from the scope of the present invention.

REFERENCE SINGS LIST