Communications: radio wave antennas – Antennas – With vehicle
Reexamination Certificate
2002-11-27
2004-09-21
Chen, Shih-Chao (Department: 2821)
Communications: radio wave antennas
Antennas
With vehicle
C343S711000, C343S788000
Reexamination Certificate
active
06795032
ABSTRACT:
This application is based on and claims priority under 35 U.S.C. § 119 with respect to Japanese Application No. 2001-363406 filed on Nov. 28, 2001, the entire content of which is incorporated herein by reference.
FIELD OF THE INVENTION
This invention generally relates to an antenna device. More particularly, the present invention pertains to an antenna which is provided inside of a door handle for opening and closing a door, for communicating with an outside.
BACKGROUND OF THE INVENTION
A known antenna device is disclosed in Japanese Patent Laid-Open Publication No. 2001-308629. The disclosed device is shown in
FIGS. 6
,
7
.
An antenna device
51
, which is used as a part of a keyless entry device of a vehicle, is provided inside of a door handle
52
for opening a vehicle door
60
. The antenna device
51
includes a first antenna
55
and a second antenna
58
. The first antenna
55
includes a coil
54
wound around a ferrite core
53
and a resonant capacitor C
6
connected to the ferrite core
53
in parallel which constitutes a parallel resonant circuit. The second antenna
58
includes a circular coil
56
accommodating therein the ferrite core
53
, a link coil
57
which is formed by one end portion of the circular coil
56
being wound a predetermined number of times around the ferrite core
53
, and a resonant capacitor C
7
connected to the circular coil
56
in series which constitutes a series resonant
5
circuit.
An axial direction of the circular coil
56
is provided perpendicular to an outer surface of the vehicle door. A magnetic field component Hy generated by the circular coil
56
extends in a direction, making an angle of 90 degrees relative to the vehicle door (y-direction in FIG.
7
). The vehicle door is a conductive board so that an image of a magnetic field component −Hy in an opposite direction to the magnetic field component Hy is generated by the vehicle door. The magnetic field component Hy generated by the circular coil
56
is thus cancelled by the magnetic field component −Hy in the opposite direction. In order to solve this problem, the antenna device
51
is provided with an electromagnetic wave absorbing material
59
between the circular coil
56
and the vehicle door
60
.
However, a number of parts is increased and an assembly condition is lowered by providing the electromagnetic wave absorbing material
59
, which is also restricted by a size of the door handle.
Thus, a need exists for the antenna device which addresses at least the foregoing drawback associated with other known antenna devices.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an antenna device which can ensure a required magnetic field strength generated by an antenna without increasing a number of parts.
According to a first aspect of the present invention, the antenna device includes a door handle provided outside of a vehicle door for opening the vehicle door, and the antenna provided inside of the door handle and generating a magnetic field component in a direction different from a perpendicular direction to an outer surface of the vehicle door.
According to a second aspect of the present invention, the antenna includes a first antenna for generating a first magnetic field component and a second antenna for generating a second magnetic field component. The first magnetic field component is generated in approximately parallel to the outer surface of the vehicle door. The second magnetic field component is generated perpendicular to the first magnetic field component.
According to a third aspect of the present invention, the first antenna includes a first resonant circuit having a first coil which axial direction is in parallel to the outer surface of the vehicle door and a first resonant capacitor connected to the first coil. The second antenna includes a second resonant circuit having a second coil which axial direction is perpendicular to the axial direction of the first coil and provided outside of the first antenna, a link coil connected to the second coil and wound in the same direction as that of the first coil, and a second resonant capacitor connected to the link coil.
According to a fourth aspect of the present invention, the antenna further includes a third antenna for generating a third magnetic field component, a fourth antenna for generating a fourth magnetic field component, and a fifth antenna for generating a fifth magnetic field component. The third magnetic field component is generated in approximately parallel to the outer surface of the vehicle door. The fourth magnetic field component is generated perpendicular to the third magnetic field component. In addition, the fifth magnetic field component is generated in approximately parallel to the outer surface of the vehicle door and also perpendicular to the third magnetic field component.
According to a fifth aspect of the present invention, the third antenna includes a third resonant circuit having a third coil which axial direction is in parallel to the outer surface of the vehicle door and a third resonant capacitor connected to the third coil. The fourth antenna includes a fourth resonant circuit having a fourth coil which axial direction is perpendicular to the axial direction of the third coil and provided outside of the third antenna, a link coil connected to the fourth coil and wound in the same direction as that of the third coil, and a fourth resonant capacitor connected to the link coil. Further, the fifth antenna includes a fifth resonant circuit having a fifth coil provided inside of the third antenna and the fourth antenna and which axial direction is in parallel to the outer surface of the vehicle door and also perpendicular to the axial direction of the third coil.
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patent: 5134392 (1992-07-01), Takeuchi et al.
patent: 6400330 (2002-06-01), Maruyama et al.
patent: 6556125 (2003-04-01), Rohrl
patent: 6577228 (2003-06-01), Tsuchida et al.
patent: 2002/0163474 (2002-11-01), Ieda et al.
patent: 1998-98211 (1998-12-01), None
patent: 102 07 944 (2002-11-01), None
patent: 0 943 764 (1999-09-01), None
patent: 1 083 280 (2001-03-01), None
patent: 10-163746 (1998-06-01), None
patent: 2001-308629 (2001-11-01), None
patent: 2002-252521 (2002-09-01), None
patent: WO 02/095873 (2002-11-01), None
Ieda Kiyokazu
Murakami Yuichi
Mushiake Eiji
Aisin Seiki Kabushiki Kaisha
Burns Doane Swecker & Mathis L.L.P.
Chen Shih-Chao
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