This application claims the benefit of Japanese Patent Application No. 2004-188727 filed in Japan on Jun. 25, 2004, which is hereby incorporated by reference.
1. Field of the Invention
The present invention relates to an in-vehicle antenna apparatus mounted on a windowpane of a vehicle, such as an automobile, and particularly, to an in-vehicle antenna apparatus in which a metal plate soldered on a radiation conductor functions as a ground.
2. Description of the Related Art
A conventional in-vehicle antenna apparatus is provided with a radiation conductor disposed on an inner surface of rear glass or front glass of a vehicle, and an electronic circuit unit that includes a pre-amplifying circuit and that is attached to the inner surface, such that the in-vehicle antenna apparatus is capable of, for example, receiving a circularly-polarized wave or a linearly-polarized wave sent from a satellite or a ground-based station. In comparison with other types of antenna apparatuses that are set on the exterior of a vehicle, such as a roof, this type of antenna apparatus is advantageous in having a longer lifespan and a lower possibility of being stolen. Furthermore, in comparison with antenna apparatuses that are set in the vicinity of the inner surface of a windowpane of a vehicle, this type of antenna apparatus is advantageous in providing a good space factor and a wide angle of view.
In an in-vehicle antenna apparatus of this type, the electronic circuit unit attached to the inner surface of a sheet of glass, such as rear glass or front glass, facing the inside of the vehicle includes a housing that houses a circuit substrate provided with, for example, a pre-amplifying circuit. In the electronic circuit unit, a radiation conductor having a predetermined shape and disposed on the sheet of glass is electrically connected with the circuit substrate via appropriate means so that the radiation conductor can receive electricity and load a received signal.
Japanese Unexamined Patent Application Publication No. 6-53722 (p. 2 to p. 3,
In such a conventional in-vehicle antenna apparatus, in view of the fact that the conductor segment protruding from the housing is soldered to the radiation conductor in order to achieve an electrical and mechanical connection of the electronic circuit unit, the conductor segment requires a suitable dimension and therefore has a large heat capacity. This is problematic in that the heating time for the soldering process takes too much time. Furthermore, in this example of a conventional in-vehicle antenna apparatus, the electronic circuit unit, which is an integrated unit, is fixed to the sheet of glass by, for example, soldering. This is problematic in view of the fact that when the circuit substrate is to be inspected or replaced with a new one, it is necessary to perform complicated processes, such as demounting the electronic circuit unit from the sheet of glass and remounting the electronic circuit unit back to the sheet of glass, and thus makes the maintenance difficult.
Accordingly, it is an object of the present invention to provide an in-vehicle antenna apparatus in which a soldering process with respect to a radiation conductor can be completed within a small amount of time.
In order to achieve the aforementioned object, the present invention provides an in-vehicle antenna apparatus which includes a sheet of glass serving as a windowpane installed in a vehicle; a radiation conductor disposed on an inner surface of the sheet of glass facing an inside of the vehicle; and a sheet-metal base plate soldered on the radiation conductor. A cutout section is provided near a soldering section of the base plate so as to form a narrow section that connects the soldering section and other sections of the base plate.
Accordingly, when the base plate having the narrow section as the connecting section between the soldering section and the other sections of the base plate is soldered onto the radiation conductor, the heat applied to the soldering section during the soldering process is less likely to be transmitted to the other sections even if the overall heat capacity of the base plate is large. Consequently, the soldering process can be completed within a small amount of time.
Furthermore, the in-vehicle antenna apparatus may further include a circuit substrate electrically connected with the radiation conductor; and a housing which houses the circuit substrate such that the housing is attached to the base plate. Accordingly, since the housing that houses the circuit substrate is, for example, screwed on the base plate that is preliminarily fixed on the sheet of glass, it is not necessary to perform complicated processes, such as demounting and remounting processes, when the circuit substrate is to be inspected or replaced with a new one. As a result, this allows for easier maintenance.
Furthermore, according to the in-vehicle antenna apparatus, the soldering section of the base plate is preferably provided with a protrusion which protrudes towards the radiation conductor, the protrusion abutting on the radiation conductor such that a solder-accumulation space is formed around the protrusion. Accordingly, this ensures at least a specific amount of solder to be disposed between the soldering section of the base plate and the radiation conductor so as to prevent strength reduction caused by a lack of solder. In this case, the base plate is more preferably provided with a plurality of height-adjustment portions disposed at different positions and distant from the soldering section, each height-adjustment portion having substantially the same dimension as the protrusion and protruding towards the sheet of glass. Thus, the base plate faces the sheet of glass in a point-contact fashion, thereby ensuring the protrusion of the soldering section to abut on the radiation conductor during the attachment process of the base plate. Accordingly, this prevents undesirable rising of the base plate.
Furthermore, according to the in-vehicle antenna apparatus, the base plate is preferably bonded to the sheet of glass via moisture curing resin. Accordingly, the bonding strength of the base plate with respect to the sheet of glass is increased. Moreover, during the attachment process of the base plate, since the soldering section may be soldered to the radiation conductor while the moisture curing resin disposed between the base plate and the sheet of glass is still in an unhardened state, it is not necessary to temporarily fix the base plate.
Accordingly, the in-vehicle antenna apparatus of the present invention, which is mounted on the inner surface of a windowpane of a vehicle, is provided with the sheet-metal base plate soldered on the radiation conductor. Since the connecting section between the soldering section and the other sections of the base plate is defined by the narrow section, the heat applied to the soldering section during the soldering process is less likely to be transmitted to the other sections. This achieves an in-vehicle antenna apparatus in which the soldering process with respect to the radiation conductor can be completed within a small amount of time.
Embodiments of the present invention will now be described with reference to the drawings.
Referring to
The ground-based antenna device 100 will first be described with reference to FIGS. 2 to 8. The ground-based antenna device 100 is a slot antenna device and mainly includes the electronic circuit unit 1 attached to the inner surface of the rear glass 51 facing the inside of the vehicle 50, and the radiation conductor 2 disposed on the inner surface of the rear glass 51. The electronic circuit unit 1 includes the base plate 4 formed of a sheet metal, which is fixed on the inner surface of the rear glass 51 and is provided with a projecting reflector plate 3; a circuit substrate 6 electrically connected with the radiation conductor 2 via the coaxial feeder cable 5; a sheet-metal housing 7 that houses the circuit substrate 6 and is attached to the base plate 4; a coaxial cable (output cable) 8 whose first end is connected to the circuit substrate 6 and whose second end is connected to an external receiving unit (not shown); and a DC cable 9 for power supply.
The housing 7 includes a sheet-metal frame-body 10 that surrounds and supports the circuit substrate 6; a sheet-metal cover 11 that is engaged with the frame body 10 so as to cover the circuit substrate 6; and a sheet-metal connector-cover 12 for covering an opening 11a of the cover 11. Two projecting sections of the frame body 10, namely, two projection tabs 10a, are fixed to the base plate 4 via setscrews 13. In the electronic circuit unit 1 of the ground-based antenna device 100, the housing 7 is attached to the base plate 4 in a detachable manner, and the base plate 4 is securely fixed to the rear glass 51 with moisture curing resin 14 (see
Each component of the ground-based antenna device 100 will be described in detail. The radiation conductor 2 is a conductor layer composed of highly-conductive metal, such as Ag. Referring to
The reflector plate 3 is a rectangular metal plate that extends from the base plate 4 at an angle and that faces the radiation conductor 2. The reflector plate 3 is used for reflecting radio-waves and thus contributes to achieving a higher gain at low elevation angles. A back surface of the reflector plate 3 is provided with an angle-maintaining member 15 which is fixed to the reflector plate 3 and a section of the base plate 4 adjacent to the reflector plate 3 in a caulked manner. The angle-maintaining member 15 is formed by punching a metal plate into a predetermined shape and then bending the metal plate, and is provided with a pair of contact edges 15a for setting the positional relationship between the back surface of the reflector plate 3 and a flat surface of the base plate 4 in a relatively desired manner. Specifically, the contact edges 15a extend from the flat surface of the base plate 4 and along the back surface of the reflector plate 3, and are lines that are cut with high dimensional accuracy during the punching process of the angle-maintaining member 15. Due to the fact that the pair of contact edges 15a with high dimensional accuracy abuts on the flat surface of the base plate 4 and the back surface of the reflector plate 3, the angle of inclination of the reflector plate 3 can be set in a highly accurate manner with respect to the base plate 4. Furthermore, the angle-maintaining member 15 is also provided with a pair of erect portions 15b which face each other and extend along the respective contact edges 15a. The erect portions 15b are formed by bending two opposite segments of the metal plate at a substantially right angle in a direction in which the two contact edges 15a are opposed to each other. The angle-maintaining member 15 increases the mechanical strength of the reflector plate 3 and thus prevents undesired deformation of the reflector plate 3.
In addition to the three soldering sections 4a, the base plate 4 is also provided with two internal-thread portions 4b. Furthermore, referring to
Furthermore, the base plate 4 is also provided with a plurality of height-adjustment portions 4f at positions distant from the soldering sections 4a such that these height-adjustment portions 4f protrude towards the rear glass 51. The height-adjustment portions 4f have a semispherical shape with substantially the same dimension as the protrusions 4c. Consequently, the base plate 4 faces the rear glass 51 in a point-contact fashion, thereby ensuring the protrusions 4c of the soldering sections 4a to abut on the radiation conductor 2 during the attachment process of the base plate 4. This prevents undesirable rising of the base plate 4. Referring to
Furthermore, referring to
The first end portion of the feeder cable 5 soldered to the electric feeding points of the radiation conductor 2 extends parallel to the inner surface of the rear glass 51 towards the exterior of the frame body 10. Since this parallel-extending portion of the feeder cable 5 is positioned by the pair of supporting segments 4g and the rear glass 51 by being sandwiched therebetween, this portion of the feeder cable 5 above the rear glass 51 can extend efficiently along a predetermined path. On the other hand, since the feeder cable 5 extending outward from the frame body 10 can be positioned readily by hooking the feeder cable 5 onto the hook segment 4h, the feeder cable 5 can also extend efficiently adjacent to the exterior of the frame body 10. Referring to
As shown in
By fastening the setscrews 13 extending through the corresponding projection tabs 10a to the corresponding internal-thread portions 4b, the frame body 10 is secured to the base plate 4 preliminarily fixed on the rear glass 51. Referring to
The arm segment 10f extending from the side wall 10d of the frame body 10 is provided for holding the coaxial cable 8. The arm segment 10f is provided with a cutout notch 10g whose opening side is relatively narrower. By press-fitting a heat shrinkable tube 18 wrapped around the coaxial cable 8 into the cutout notch 10g, the coaxial cable 8 can be engaged to the arm segment 10f in a single-step fashion, and moreover, the inner conductor and the outer conductor of the coaxial cable 8 can be securely protected. Accordingly, this achieves a stable orientation of the coaxial cable 8 during the assembly process, and also prevents the connecting section of the coaxial cable 8 from being damaged in a case where a pulling force acts upon the coaxial cable 8. Furthermore, by changing the metallic arm segment 10f into a desired shape, the orientation of the coaxial cable 8 can be readily corrected.
Referring to
The cover 11 is provided with the opening 11a which is to be covered by the connector cover 12. Since the connector 17 faces the opening 11a, the connector 16 of the feeder cable 5 can be connected to the connector 17 of the circuit substrate 6 in a state where the frame body 10 holding the circuit substrate 6 is capped with the cover 11. The cover 11 is provided with bent segments 11b substantially around the entire peripheral region of the cover 11. The bent segments 11b fit around the side walls 10b to 10e of the frame body 10 and are provided with a plurality of engagement protrusions 11c that protrude inward. The engagement protrusions 11c are provided at positions corresponding to the small holes 10h of the frame body 10. The resilience of the bent segments 11b allows the engagement protrusions 11c to be press-fitted into the corresponding small holes 10h. Consequently, the cover 11 can be readily engaged to the frame body 10 in a snap-fit fashion. Since the circuit substrate 6 is installed in the frame body 10 before the engagement process of the cover 11, the installation process of the circuit substrate 6 is simplified.
Referring to
When the frame body 10 capped with the cover 11 is fixed to the rear glass 51 via the base plate 4, a region of the cover 11 proximate the side wall 10b of the frame body 10 defines a lower region disposed closer to the ground. Consequently, the lower region of the cover 11 is provided with two rectangular drainage holes 11d. The drainage holes 11d allow water droplets entering an internal space defined by the component-holding surface 6a of the circuit substrate 6, the frame body 10, the cover 11, and the connector cover 12 to be drained outward quickly so as to prevent water from accumulating in the internal space.
An assembly process of the ground-based antenna device 100 described above will now be described. Firstly, the radiation conductor 2 is formed on an inner surface of a sheet of glass constituting the rear glass 51. Subsequently, the first end portion of the feeder cable 5 is soldered to the electric feeding points of the radiation conductor 2, and the soldering sections 4a of the base plate 4 are soldered to predetermined positions of the radiation conductor 2. In this case, the first end portion of the feeder cable 5 is positioned by the supporting segments 4g of the base plate 4 and the sheet of glass by being sandwiched therebetween. Moreover, the moisture curing resin 14 is preliminarily applied to the bottom surface of the base plate 4. Secondly, the frame body 10 is fixed to the internal-thread portions 4b of the base plate 4 via the setscrews 13. Here, the circuit substrate 6 is preliminarily installed in the frame body 10; the ends of the coaxial cable 8 and the DC cable 9 are preliminarily soldered on the circuit substrate 6; and the cover 11 is preliminarily engaged with the frame body 10. Moreover, when the frame body 10 is to be screwed onto the base plate 4, the feeder cable 5 is pulled toward the exterior of the frame body 10 via the clearance recess 10j of the side wall 10b. Thirdly, after fixing the frame body 10 to the base plate 4, the feeder cable 5 hooked on the hook segment 4h is pulled into the opening 11a of the cover 11 via the supporting notch 11e. Fourthly, the connector 16 attached to the second end portion of the feeder cable 5 is connected to the connector 17 of the circuit substrate 6 facing the opening 11a. Subsequently, the connector cover 12 is mounted on the cover 11 so as to cover the opening 11a, whereby an attachment process for attaching the electronic circuit unit 1 to the sheet of glass constituting the rear glass 51 is completed.
The satellite antenna device 200 will now be described. The satellite antenna device 200 is a patch antenna device and mainly includes the electronic circuit unit 21 attached to the inner surface of the rear glass 51 facing the inside of the vehicle 50, and the radiation conductor 22 and a ground conductor 23 disposed on the inner surface of the rear glass 51. The electronic circuit unit 21 includes the base plate 24 formed of a sheet metal, which is fixed on the inner surface of the rear glass 51; a circuit substrate 26 electrically connected with the radiation conductor 22 and the ground conductor 23 via a coaxial feeder cable 25; a sheet-metal housing 27 that houses the circuit substrate 26 and is attached to the base plate 24; a coaxial cable (input-output cable) 28 whose first end is connected to the circuit substrate 26 and whose second end is connected to an external receiving unit (not shown); and the DC cable 9 for supplying the ground-based antenna device 100 with power.
The housing 27 includes a sheet-metal rectangular frame body 30 that surrounds and supports the circuit substrate 26; a sheet-metal cover 31 that is engaged with the frame body 30 so as to cover the circuit substrate 26; and a sheet-metal connector cover 32 for covering an opening 31a of the cover 31. Multiple sections of the frame body 30 are fixed to the base plate 24 via setscrews 33. In the electronic circuit unit 21 of the satellite antenna device 200, the housing 27 is attached to the base plate 24 in a detachable manner, and the base plate 24 is securely fixed to the rear glass 51 with moisture curing resin 34 (see
Each component of the satellite antenna device 200 will be described in detail. Referring to
The base plate 24 has a rectangular shape with an opening 24a, and is provided with internal-thread portions 24b at multiple positions. By fastening the setscrews 33 extending through corresponding projection tabs 30a of the frame body 30 to the corresponding internal-thread portions 24b, the frame body 30 is secured to the base plate 24. As shown in
Referring to
Referring to
As shown in
The cover 31 is provided with the opening 31a which is to be covered by the connector cover 32. Since the connector 37 faces the opening 31a, the connector 36 of the feeder cable 25 can be connected to the connector 37 of the circuit substrate 26 in a state where the frame body 30 holding the circuit substrate 26 is capped with the cover 31. The cover 31 is provided with bent segments 31b substantially around the entire peripheral region of the cover 31. The bent segments 31b fit around the side walls 30b to 30e of the frame body 30 and are provided with a plurality of engagement protrusions 31c that protrude inward. The engagement protrusions 31c are provided at positions corresponding to the small holes 30h of the frame body 30. The resilience of the bent segments 31b allows the engagement protrusions 31c to be press-fitted into the corresponding small holes 30h. Consequently, the cover 31 can be readily engaged to the frame body 30 in a snap-fit fashion. Since the circuit substrate 26 is installed in the frame body 30 before the engagement process of the cover 31, the installation process of the circuit substrate 26 is simplified.
When the frame body 30 capped with the cover 31 is fixed to the rear glass 51 via the base plate 24, a region of the cover 31 proximate the side wall 30b of the frame body 30 defines a lower region disposed closer to the ground. Consequently, the lower region of the cover 31 is provided with four rectangular drainage holes 31d. The drainage holes 31d allow water droplets entering an internal space defined by the component-holding surface 26a of the circuit substrate 26, the frame body 30, the cover 31, and the connector cover 32 to be drained outward quickly so as to prevent water from accumulating in the internal space.
An assembly process of the satellite antenna device 200 described above will now be described. Firstly, the radiation conductor 22 and the ground conductor 23 are formed on the inner surface of the sheet of glass constituting the rear glass 51. The first end portion of the feeder cable 25 is then soldered to predetermined positions of the radiation conductor 22 and the ground conductor 23. Secondly, the base plate 24 is securely fixed to the inner surface of the sheet of glass by using, for example, the moisture curing resin 34. The engagement portion 30f of the frame body 30 is then inserted into and positioned within the opening 24a. Subsequently, the frame body 30 is fixed to the internal-thread portions 24b of the base plate 24 via the setscrews 33. Here, the circuit substrate 26 is preliminarily installed in the frame body 30; the ends of the coaxial cable 28 and the DC cable 9 are preliminarily soldered on the circuit substrate 26; and the cover 31 is preliminarily engaged with the frame body 30. Moreover, when the frame body 30 is to be screwed onto the base plate 24, the feeder cable 25 is pulled toward the exterior of the frame body 30 via a clearance recess 30m (see
The unique advantages of the above embodiment will be described below in detail. The unique advantages of the ground-based antenna device 100 will be described first. In detail, due to the fact that the connecting sections between the soldering sections 4a and the other sections of the base plate 4 are defined by the narrow sections 4e, these other sections of the base plate 4 do not receive much heat during the heating process for soldering the base plate 4 to the radiation conductor 2. Consequently, the soldering process can be completed within a small amount of time. Furthermore, each of the soldering sections 4a is provided with one of the protrusions 4c such that a solder-accumulation space is formed around the protrusion 4c. This prevents strength reduction caused by a lack of solder in the soldering sections 4a, whereby a highly reliable solder connection is achieved.
Furthermore, in the ground-based antenna device 100, the back surface of the reflector plate 3 is provided with the angle-maintaining member 15. Specifically, due to the fact that the contact edges 15a with high dimensional accuracy are in contact with the back surface of the reflector plate 3 and the flat surface of the base plate 4, the angle of inclination of the reflector plate 3 is set in a highly accurate manner with respect to the sheet of glass (rear glass) 51. Accordingly, a desired antenna performance can be achieved. Moreover, the angle-maintaining member 15 significantly improves the mechanical strength of the reflector plate 3, and thus reduces the possibility of the reflector plate 3 deforming into an undesired shape in response to receiving an external force during, for example, the assembly process. Accordingly, this further contributes to higher reliability in view of strength.
Furthermore, in the ground-based antenna device 100, the first end portion of the feeder cable 5 connected to the electric feeding points of the radiation conductor 2 is positioned by the supporting segments 4g and the sheet of glass (rear glass) 51 by being sandwiched therebetween, and moreover, the feeder cable 5 extending adjacent to the exterior of the housing 7 is positioned by the hook segment 4h and the supporting notch 11e. Accordingly, the feeder cable 5 can extend efficiently along a predetermined path.
Furthermore, in the ground-based antenna device 100, the coaxial cable 8 is held by the arm segment 10f extending from the frame body 10. This achieves a stable orientation of the coaxial cable 8 during the assembly process, and also prevents the connecting section of the coaxial cable 8 from being damaged in a case where a pulling force acts upon the coaxial cable 8. Moreover, by changing the metallic arm segment 10f into a desired shape, the orientation of the coaxial cable 8 can be readily corrected. Accordingly, the fixing process of the coaxial cable 8 can be performed in an extremely simple manner without using, for example, binders and adhesive tapes.
Furthermore, in the ground-based antenna device 100, the frame body 10 housing the circuit substrate 6 is screwed on the base plate 4 that is preliminarily fixed on the sheet of glass (rear glass) 51. This eliminates the need for performing complicated processes, such as demounting and remounting processes, when the circuit substrate 6 is to be inspected or replaced with a new one, and thus allows for easier maintenance.
Furthermore, in the ground-based antenna device 100, the frame body 10 and the cover 11 included in the housing 7 are respectively provided with the drainage holes 10i and the drainage holes 11d. Since the drainage holes 10i, 11d are provided at the bottommost portion of the electronic circuit unit 1 attached to the rear glass 51 that is disposed at an angle with respect to the ground, the component-holding surface 6a of the circuit substrate 6 is prevented from being immersed in water even when water droplets enter the internal space of the housing 7. Accordingly, a malfunction and failure caused by intrusion of water droplets are less likely to occur in the ground-based antenna device 100 such that high reliability is guaranteed over a long period of time.
Next, the unique advantages of the satellite antenna device 200 will be described. In detail, since the undersurface of the circuit substrate 26 constitutes the radio-wave reflective surface 26b that faces the radiation conductor 22 and the ground conductor 23, a higher radiation gain can be attained in the incoming direction of a tuned radio-wave. In view of the fact that the height of the radio-wave reflective surface 26b must be set accurately with respect to the radiation conductor 22 and the ground conductor 23, since the frame body 30 housing the circuit substrate 26 according to the above embodiment is positioned properly in the planar direction of the base plate 24 via the engagement portion 30f and in the thickness direction of the base plate 24 via the stoppers 30g, the circuit substrate 26 is automatically disposed at a predetermined position when the frame body 30 is mounted onto the base plate 24. This means that the height of the circuit substrate 26 is set accurately with respect to the radiation conductor 22, and moreover, prevents an undesired gap from being formed between the frame body 30 and the base plate 24. In other words, since the electronic circuit unit 21 of the satellite antenna device 200 is an assembly structure in which the height of the radio-wave reflective surface 26b is set in a highly accurate manner, a high antenna performance is guaranteed. Moreover, since the frame body 30 can be fabricated easily due to having a simple structure, the dimensional accuracy of the engagement portion 30f and the stoppers 30g can be readily improved.
Furthermore, similar to the ground-based antenna device 100, the satellite antenna device 200 is advantageous in that the frame body 30 and the cover 31 included in the housing 27 are respectively provided with the drainage holes 30i and the clearance holes 30k, functioning also as drainage holes, and the drainage holes 31d. Since the drainage holes 30i, 31d and the clearance holes 30k are provided at the bottommost portion of the electronic circuit unit 21 attached to the rear glass 51 that is disposed at an angle with respect to the ground, the component-holding surface 26a and the radio-wave reflective surface 26b of the circuit substrate 26 are prevented from being immersed in water even when water droplets enter the internal space of the housing 27. Accordingly, a malfunction and failure caused by intrusion of water droplets are less likely to occur in the satellite antenna device 200 such that high reliability is guaranteed over a long period of time.
Furthermore, similar to the ground-based antenna device 100, the satellite antenna device 200 is advantageous in that the frame body 30 housing the circuit substrate 26 is screwed on the base plate 24 that is preliminarily fixed on the sheet of glass (rear glass) 51. This eliminates the need for performing complicated processes, such as demounting and remounting processes, when the circuit substrate 26 is to be inspected or replaced with a new one, and thus allows for easier maintenance.
Although the above embodiment describes an in-vehicle antenna apparatus in which the ground-based antenna device 100 and the satellite antenna device 200 are arranged in a side-by-side manner and operate in a mutually complementary manner, the present invention is not limited to such a structure. For example, the scope of the present invention may include an in-vehicle antenna apparatus provided with only one of the two antenna devices. Furthermore, the in-vehicle antenna apparatus may alternatively be mounted on, for example, the front glass of the vehicle instead of the rear glass.
Number | Date | Country | Kind |
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2004-188727 | Jun 2004 | JP | national |