Communications: radio wave antennas – Antennas – With vehicle
Reexamination Certificate
2001-01-18
2001-10-30
Ho, Tan (Department: 2821)
Communications: radio wave antennas
Antennas
With vehicle
C343S728000
Reexamination Certificate
active
06310580
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an antenna structure for a vehicle, which includes an antenna element disposed on a window glass of an automobile or the like.
BACKGROUND OF THE INVENTION
In the field of automobiles as representative vehicles, a so-called glass antenna, which is disposed as a print or sticker antenna on the surface of a window glass such as a front window, and receives radio wave (signal wave) outside the vehicle, has been proposed.
As an example of such glass antenna, preceding Japanese Patent Laid-Open No. 9-130124 by the present applicant and U.S. Pat. No. 6,008,767 as its corresponding U.S. application propose an antenna structure for a vehicle that disposes a reverse-convex-shaped antenna element (that is, the antenna element has convex shape in lower direction) on a front window to receive TV (television) radio wave.
According to the aforementioned prior arts, TV radio wave can be satisfactorily received in a vehicle on the move without any antenna element that protrudes outside the vehicle.
However, as general characteristics of an antenna element, since the optimal size and shape largely vary depending on the wavelength (frequency range) of radio wave to be received, a reverse-convex-shaped antenna element must have a considerably large size if it is used as that for receiving FM (frequency modulation) or AM (amplitude modulation) wave, and as such it disturbs the driver's sight on the front window.
When an antenna element is formed as a print antenna, if the pattern of the antenna element is partially disconnected for some reason (e.g., upon cleaning, exchanging an automobile inspection sticker, or the like), the reception characteristics of the antenna element considerably change from original reception characteristics. If an antenna element having a large size is used on the surface (the surface on the passenger room side) of a front window glass to satisfactorily receive FM or AM wave, troubles due to such pattern disconnection are highly likely to occur.
SUMMARY OF THE INVENTION
It is, therefore, an object of the present invention to provide an antenna structure for a vehicle, which satisfactorily receives FM and AM waves on a front window glass without disturbing driver's sight.
In order to achieve the above object, a first antenna structure for a vehicle according to the present invention is characterized by the following arrangement.
That is, an antenna structure for a vehicle including an antenna which is disposed on a front window glass (
11
) and is used to receive FM and AM waves, is characterized by comprising a loop-shaped first antenna element (
1
) disposed near an upper edge portion of the front window glass, one second antenna element (
2
) which is connected in a DC manner to a lower side portion of the loop shape defined by the first antenna element, and has a lower end portion vertically descending toward a lower edge portion of the front window glass, and a feeder distribution center (P) provided to an upper side portion of the loop shape defined by the first antenna element (see FIG.
1
).
According to the antenna structure for a vehicle, FM and AM waves can be satisfactorily received on the front window glass without disturbing driver's sight.
In the first antenna structure for a vehicle, the first and second antenna elements (e.g., print antenna elements) are preferably formed of silver paste containing dark carbon particles. With this structure, the resistance (impedance) can be adjusted to a desired value without increasing the width of each antenna element, and driver's sight can be prevented from being impaired.
Also, the first antenna element is formed into, e.g., a reverse-convex shape, and a base (
13
) of a rearview mirror (
14
) is disposed inside the reverse-convex shaped portion (see FIG.
2
). With this structure, since the rearview mirror is attached to the base inside of the reverse-convex shaped portion, and the first antenna element is hidden from the vision of a passenger, appearance of the antenna can be improved.
Alternatively, in order to achieve the above object, a second antenna structure for a vehicle, including an antenna which is disposed on a front window glass (
11
) as a print antenna and is used to receive FM and AM waves, is characterized by comprising a C-shaped first antenna element (
5
) which is disposed near an upper edge portion of the front window glass and has an opening facing a lower edge portion of the front window glass, two second antenna elements (
6
) which are respectively connected to ends of the C-shaped opening defined by the first antenna element, and substantially vertically descend toward the lower edge portion of the front window glass to have a spacing smaller than a maximum width of the first antenna element in a widthwise direction of a vehicle, a third antenna element (
7
) which is connected in a DC manner to positions different from lower end portions of the second antenna elements so as to connect the two second antenna elements to each other, and a feeder distribution center (P) provided to an upper side portion of the C shape defined by the first antenna element (see FIG.
10
).
According to the antenna structure for a vehicle, FM and AM waves can be satisfactorily received on the front window glass without disturbing driver's sight. Furthermore, according to the antenna structure for a vehicle, when the second antenna element is disposed on the front window glass as a print antenna, and is disconnected at some position, the predetermined effective length of the antenna element can be prevented from becoming extremely short, thus minimizing deterioration of predetermined reception performance.
In the second antenna structure for a vehicle, the first to third antenna elements are preferably formed of silver paste containing dark carbon particles. With this structure, the resistance (impedance) can be adjusted to a desired value without increasing the width of each antenna element, and driver's sight can be prevented from being impaired.
For example, the third antenna element is preferably disposed on the front window glass at a level of a back surface of a rear view mirror. With this structure, since the third antenna element is hidden by the rearview mirror from the vision of a passenger, appearance of the antenna can be improved.
At this time, the third antenna element may be connected to upper end portions of the two second antenna elements to define a loop shape together with the C-shaped first antenna element (see FIG.
22
), or a plurality of third antenna elements equivalent to the third antenna element may be disposed at vertically different positions of the two second antenna elements (see FIGS.
13
and
14
).
In the first or second antenna structure for a vehicle, at least the second antenna element is preferably disposed at substantially the center of the front window glass in the widthwise direction of the vehicle. With this structure, reception performance can be maximized on the front window glass.
Preferably, the first antenna element is preferably disposed on the front window glass above a level of a lower end portion of a rearview mirror (
14
). With this structure, since the first antenna element is hidden by the rearview mirror from the vision of a passenger, the appearance of the antenna can be improved.
For example, a shield member is preferably provided between the second antenna element and an electronic device equipped inside an instrument panel below the front window glass to shield electrical connection therebetween.
In a preferred embodiment, the shield member may use conductive paint applied to a cover of the instrument panel, a cover of the instrument panel which is made of a conductive resin material, or a conductive planar or mesh material disposed along the instrument panel.
According to the aforementioned structure, reception performance can be prevented from being adversely influenced by electrical noise generated by an electronic device arranged inside the instrument panel.
Other
Shigeta Kazuo
Taniguchi Tatsuaki
Ho Tan
Mazda Motor Corporation
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