Telecommunications – Transmitter and receiver at same station – Having particular housing or support of a transceiver
Reexamination Certificate
1998-08-18
2001-11-06
Maung, Nay (Department: 2681)
Telecommunications
Transmitter and receiver at same station
Having particular housing or support of a transceiver
C455S575100, C455S550100
Reexamination Certificate
active
06314273
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a mobile telecommunication apparatus such as a portable telephone and a PHS telephone.
2. Description of the Prior Art
FIG. 18
illustrates a conventional mobile telecommunication apparatus shown in Japanese Laid-Open Patent Publication No. 7-74807, “A Portable Telephone”.
FIG. 18
includes a body
1
of a telecommunication apparatus, an antenna
2
, a transmitter
3
, and a receiver
4
.
FIG. 19
is a perspective view which illustrates an internal construction of a conventional mobile telecommunication apparatus. FIG.
20
and
FIG. 21
are sectional views seen from a line A-B and a line C-D in
FIG. 19
, respectively.
In FIG.
19
-
FIG. 21
, the mobile telecommunication apparatus includes a printed circuit board
5
, a radio circuit
6
formed on the printed circuit board
5
, a control circuit
7
formed on the printed circuit board
5
, a voice circuit
8
, shield cases
9
a
and
9
b
surrounding the radio circuit
6
, a feeder line
10
, a feeding circuit
11
, an earth conductor
12
for the radio circuit
6
, an earth conductor
13
for the control circuit, an earth conductor
14
formed between the earth conductors
12
and
13
, and a battery
15
.
The printed circuit board
5
is actually a multi-layered circuit board. Parts constructing the radio circuit
6
and the control circuit
7
are mounted on the printed circuit board
5
. The voice circuit
8
is included in the control circuit
7
.
The shield cases
9
a
and
9
b
are equipped to shield external noise coming into the radio circuit
6
and to prevent the escape of radiation to the outside. However, since the shield construction around the control circuit
7
is complicated, the shield construction is not generally included.
The antenna
2
generally uses a &lgr;/4 monopole antenna (&lgr;indicates a wavelength of the frequency being used) or a &lgr;/2 monopole antenna. Impedance of a &lgr;/4 monopole antenna is easily matched and the structure of the feeding circuit
11
is relatively simple. The radiation characteristic of the &lgr;/2 monopole antenna is better than the &lgr;/4 monopole antenna although the construction of feeding circuit
11
becomes a little bit complicated due to impedance matching. The earth conductor
12
, the earth conductor
13
, and the earth conductor
14
arc equipped on the printed circuit board
5
. The earth conductor
14
is equipped between the earth conductor
12
and the earth conductor
13
, and they are connected electrically.
The operation of the conventional mobile telecommunication apparatus is explained below. During transmitting, a human voice from a transmitter
3
is converted to a voice signal through the voice circuit
8
in the control circuit
7
. The voice signal is modulated to a high frequency signal by the radio circuit
6
. The modulated high frequency signal is radiated from the antenna
2
via the feeding circuit
11
.
On the other hand, during receiving, a high frequency modulated signal which enters the radio circuit
6
via the feeding circuit
11
from the antenna
2
is demodulated to a voice signal through a demodulator circuit. The demodulated voice signal is transduced into an audible human voice by the receiver
4
via the voice circuit
8
in the control circuit
7
. Also, the battery
15
supplies power to the radio circuit
6
and the control circuit
7
.
FIG. 22
illustrates an example of a longitudinal current distribution on the side of the printed circuit board
5
facing the battery
15
in the conventional mobile telecommunication apparatus using a &lgr;/4 monopole antenna as the antenna
2
.
In
FIG. 22
, numerals
16
and
17
indicate current amplitude and phase which distribute along the antenna
2
and the radio circuit
6
, respectively. Numerals
18
and
19
indicate current amplitude and phase which distribute along the control circuit
7
, respectively.
Current flowing through the earth conductor
14
equipped between the radio circuit
6
and the control circuit
7
is amplified by a parallel plane mode oscillation between the battery
15
and the control circuit
7
that generates a sinewave current
18
having large amplitude.
This current having a sinewave distribution greatly influences the voice circuit
8
in the control circuit
7
. This current generates noise in the voice signal which is then transduced by the receiver
4
thereby decreasing the speech quality.
Also, the phase
19
of the current flowing along the control circuit
7
on the printed circuit board
5
is contrary to the phase
17
of current distributing between the antenna
2
and the radio circuit
6
. Therefore, the antenna gain of the telecommunication apparatus toward the horizontal direction is extremely attenuated, which decreases the available communication distance.
SUMMARY OF THE INVENTION
It is an object of the presentation to reduce current around the control circuit on the printed circuit board and to obtain a mobile telecommunication apparatus having less background noise and good antenna radiation characteristics.
According to an aspect of the invention, a mobile telecommunication apparatus includes a printed circuit board equipped in a body of the mobile telecommunication apparatus; a radio circuit including modulator circuit and a demodulator circuit arranged on the printed circuit board; a control circuit including a voice circuit for processing a voice signal arranged on the printed circuit board; a first earth conductor for grounding the radio circuit; a second earth conductor for grounding the control circuit and being continuous with the first earth conductor; an antenna connected to the radio circuit; and a slit arranged between the first earth conductor and the second earth conductor.
According to another aspcct of the invention, a mobile telecommunication apparatus includes first and second printed circuit boards equipped in a mobile telecommunication apparatus; a radio circuit including a modulator circuit and a demodulator circuit arranged on the first printed circuit board; a control circuit including a voice circuit for processing a voice signal arranged on the second printed circuit board; a first earth conductor for grounding the radio circuit on the first printed circuit board; a second earth conductors for grounding the control circuit on the second printed circuit board; a third earth conductors on the second printed circuit board being electrically connected with the second earth conductor; a connector for connecting the first earth conductor with the third earth conductor; an antenna being connected to the radio circuit; and a slit arranged between the second earth conductor and the third earth conductor.
In one preferable alternative, the antenna of the mobile telecommunication apparatus is a slot inner antenna constructed by &lgr;/4 wavelength slot arranged at one portion of the printed circuit board.
In another preferable alternative, the antenna of the mobile telecommunication apparatus is a &lgr;/4 wavelength monopole antenna protruding toward outside of the apparatus body.
The inner antenna of the mobile telecommunication apparatus can also be a &lgr;/2 monopole antenna protruding toward outside of the apparatus body which is excited from the inner antenna by way of non-contact feeding thereby providing a further alternative.
The slit is also preferably constructed by pattern etching process on the printed circuit board.
According to a further aspect of the invention,a mobile telecommunication apparatus includes a printed circuit board equipped in a body of the mobile telecommunication apparatus; a radio circuit including modulator circuit and a demodulator circuit arranged on the printed circuit board; a control circuit including a voice circuit for processing a voice signal arranged on the printed circuit board; a first earth conductor formed on a first surface of the printed circuit board for grounding the radio circuit; a second earth conductor formed on a second surface of the printed circuit board for grounding the c
Maung Nay
Mitsubishi Denki & Kabushiki Kaisha
Trinh Sonny
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