Communications: radio wave antennas – Antennas – With radio cabinet
Reexamination Certificate
2000-12-12
2002-01-15
Wong, Don (Department: 2821)
Communications: radio wave antennas
Antennas
With radio cabinet
C343S850000
Reexamination Certificate
active
06339401
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an antenna which is provided in a portable radio, represented primarily by devices for mobile communication terminal such as a portable telephone, PHS (Personal Handy Phone System), and the like. In particular, this invention relates to the antenna for portable radio which is installed to a case of the portable radio and can be freely extracted and stored therefrom/therein.
2. Description of the Related Art
An antenna which can be extracted during use, and stored inside the case of the radio when not in use, is used in this type of portable radio. Such a storable antenna comprises (a) a rod antenna section having a predetermined wavelength (one-quarter, three-eighths, one-half, etc.) when extracted from the radio case, and (b) a coil antenna section which is provided in an insulated state at the tip of the rod antenna section, and has a predetermined wavelength when projected from the radio case while the rod antenna is being stored. A feeding mechanism is provided at the antenna installation position on the radio case. The feeding mechanism electrically connects to the bottom end of the rod antenna section when the rod antenna is extracted, and electrically connects to the bottom end of the coil antenna section when the rod antenna is stored.
A conventional example of the feeding mechanism described above will be explained based on
FIGS. 8 and 9
. Firstly, the basic constitution of the antenna will be explained based on FIG.
8
. As already explained, an antenna
1
comprises a coil antenna section
10
and a rod antenna section
20
. A sleeve
12
of conductive material is provided as a feeding member at the base of the coil antenna section
10
, which is provided at the tip of the antenna
1
. A stopper
22
of conductive material is provided at the base of the antenna as a feeding member of the rod antenna section
20
, which connects to the base of the sleeve
12
. The coil antenna section
10
is provided at the tip of the antenna
1
, and comprises a coil element
14
which is wound around a cylindrical bobbin
13
provided inside a top
11
. The coil element
14
is electrically connected to the sleeve
12
, which is coupled to the base of the top
11
. The rod antenna section
20
comprises a flexible antenna tube
21
having elasticity which covers an antenna element
23
. The antenna element
23
connects to the base of the stopper
22
, provided at the base of the antenna.
When manufacturing the antenna
1
, a holder
30
is attached while the stopper
22
is in the fastened state. The holder
30
comprises a conductive member. A screw section
30
a
is provided around the outer rim of the holder
30
, and a groove
30
b
for a screw-stopping fitting is provided in a flange-like head section. A holding spring
31
is provided inside the holder
30
, and maintains electrical contact with the stopper
22
and the sleeve
12
.
FIG. 9
shows the state when the antenna
1
is attached to the radio case
2
by the holder
30
. An installation metal fitting
32
has a screw section in its inner rim, and is provided at the antenna installation position on the case
2
. The screw section
30
a
around the holder
30
screws into the screw section in the installation metal fitting
32
. A special fitting
40
, such as that shown in
FIG. 10
, is inserted into the groove
30
b
at the head of the holder
30
and clamping is carried out. A feeding spring
33
is connected to the installation metal fitting
32
, and electricity is supplied via the feeding spring
33
to a radio circuit board comprising an RF substrate
4
. A storage cylinder
34
is provided below the installation metal fitting
32
.
The conventional feeding mechanism in the antenna
1
described above has the following problems. Firstly, electrical contact resistance is high and signal transmission is unstable. According to the constitution described above, a received signal flows from the coil antenna and the rod antenna element
14
and
23
, via the sleeve
12
or the stopper
22
, the holding spring
31
, the holder
30
, the installation metal fitting
32
, and the feeding spring
33
, to the RF (Radio Frequency) substrate
4
. Transmitted signals flow along the same route in reverse, passing from the RF substrate
4
, via the feeding spring
33
, the installation metal fitting
32
, the holder
30
, the holding spring
31
, the sleeve
12
and the stopper
22
, to the coil antenna and the rod antenna element
14
and
23
. There are a great many contact points between the members which signals pass through during transmission, and consequently the electrical contact resistance becomes as high as 200 m&OHgr; to 1 &OHgr;. Furthermore, noise is liable to enter the signals at the contact points between the members during transmission, making signal transmission unstable.
Secondly, there is a serious problem regarding weight. Since portable radios such as mobile telephones and PHS, are often carried in users' pockets and the like, the total weight of the portable radio needs to be extremely light. However, in the conventional constitution described above, the weight of the main body of the antenna
1
(including the holder
30
) with the addition of the installation metal fitting
32
is approximately 2.3 g. This is an impediment to making the portable radio lighter.
Thirdly, there is a problem of workability when attaching the antenna
1
to the radio case
2
. In the above constitution, in attaching the antenna
1
to the radio, the holder
30
must be screwed to the installation metal fitting
32
of the radio. As shown in
FIG. 10
, this screwing operation requires the special fitting
40
. In addition, the torque of the clamping must be controlled, making this operation bothersome. Furthermore, there is a possibility that the groove
30
b
for joining the fitting will be damaged during the screwing operation. Moreover, the presence of the groove
30
b
for joining the fitting leads to a problem that the antenna tube
21
of the rod antenna section might be damaged by touching the edges of the groove.
Fourthly, there is a problem of variation in the sliding forces of the holding spring
31
and the sleeve
12
or the stopper
22
. In the conventional mechanism, the holding spring
31
must be provided in a small limited space inside the holder
30
. As a consequence, the holding spring
31
has a short contact piece length and little flexion. This results in an unstable sliding force between the holding spring
31
and the sleeve
12
(stopper
22
), the sliding force varying between approximately 200 to 600 g.
Fifthly, the conventional feeding mechanism comprises so many components that the cost of the antenna
1
is high.
SUMMARY OF THE INVENTION
The present invention has been achieved in order to solve the above problems. It is an object of this invention to improve the feeding mechanism of the antenna by reducing the contact resistance, stabilizing signal transmission, reducing the weight of the antenna, simplifying the operation of installing the antenna, upholding product quality, and reducing costs.
In order to achieve the above objects, a first aspect of this invention provides an antenna for portable radio comprising an antenna section which functions when extracted from a case of a portable radio, and a stopper which comprises a feeding member and is provided at the base of the antenna section. The antenna can be freely extracted from and stored in the case. A cylindrical section is provided on the case at the antenna installation position, and the stopper reaches a clipped state after being inserted into the cylindrical section. The cylindrical section comprises a plate-like feeding spring which pressingly contacts one end of the feeding member when the feeding member faces inside the cylindrical section. The plate-like feeding spring holds the antenna section and feeds electricity when the antenna section is extracted.
A second aspect of this invention provides the antenna for portable radio of the f
Clinger James
Dickstein , Shapiro, Morin & Oshinsky, LLP
Wong Don
Yokowo Co., Ltd.
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