Telecommunications – Transmitter and receiver at same station – With transmitter-receiver switching or interaction prevention
Reexamination Certificate
1998-10-23
2001-04-17
Hunter, Daniel S. (Department: 2749)
Telecommunications
Transmitter and receiver at same station
With transmitter-receiver switching or interaction prevention
C455S078000, C455S082000, C455S083000, C455S575100, C340S311200
Reexamination Certificate
active
06219532
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a movable radio terminal device which is capable of matching impedances.
DESCRIPTION OF THE PRIOR ART
A first conventional movable radio terminal device is disclosed in Japanese Unexamined Patent Prepublication (koukai) No. 23450/1995. The first conventional movable radio terminal device comprises an antenna, a radio transmitting and receiving circuit, a controlling circuit, a switching circuit, a stub, and an impedance detecting circuit. The impedance detecting circuit detects a change of an impedance of the antenna to produce an impedance change detecting signal. The controlling circuit makes the switching circuit connect the antenna to the stub so to match impedances of the antenna and an internal circuit.
Also, a second conventional movable radio terminal device is disclosed in Japanese Unexamined Patent Prepublication (koukai) No. 162618/1997. The second conventional movable radio terminal device comprises an antenna, a radio transmitting and receiving circuit, a switching circuit, a matching stub, and a plurality of stubs which are manually moved. When the second conventional movable radio terminal device is in contact with a human body, matching of impedances of the antenna and an internal circuit is executed by manually moving the stubs so that one of the stubs is connected to the matching stub.
Also, a third conventional movable radio terminal device is disclosed in Japanese Unexamined Patent Prepublication (koukai) No. 135235/1986. The third conventional movable radio terminal device comprises an antenna, a level detecting circuit, a controlling circuit, and a variable reactance element. The level detecting circuit detects, in all time, a level of one of receiving and transmitting signal to produce a detected level signal having a level value. When the level value of the detected level signal is smaller than the level value which was previously detected, the controlling circuit controls a reactance value of the variable reactance element so to match impedances of the antenna and an internal circuit.
Also, a fourth conventional movable radio terminal device is disclosed in Japanese Unexamined Patent Prepublication (koukai) No. 115090/1993. The fourth conventional movable radio terminal device comprises a first impedance matching circuit, a second impedance matching circuit, a switching circuit, a human body detecting circuit, and a controlling circuit. The human body detecting circuit detects that a human body exists near the movable radio terminal device to produce a human body detecting signal. When the controlling circuit is not supplied with the human body detecting signal, the controlling circuit makes the switching circuit connect the first impedance matching circuit to the antenna. When the controlling circuit is supplied with the human body detecting signal, the controlling circuit makes the switching circuit connect the second impedance matching circuit to the antenna.
However, each of the conventional movable radio terminal devices is incapable of precisely matching impedances of the antenna and the internal circuit.
SUMMARY OF THE INVENTION
It is therefore an object of this invention to provide a movable radio terminal device which is capable of precisely matching impedances of an antenna and an internal circuit.
Other objects of this invention will become clear as the description proceeds.
According to a first aspect of this invention, there is provided a movable radio terminal device comprising:
an antenna receiving a radio receiving signal to produce a receiving signal, the antenna receiving a transmitting signal to produce a radio transmitting signal;
a level detecting circuit connected to the antenna for detecting a level of one of the receiving signal and the transmitting signal to produce a detected level signal having a detected level value;
first through N-th impedance matching circuits having first through N-th impedances which are different, where N represents an integer greater than one;
a switching circuit connected to the antenna and to the first through N-th impedance matching circuits for connecting, in response to one of first through N-th matching switching control signals, the antenna to one of the first through N-th impedance matching circuits;
a transmitting circuit connected to the transmitting and receiving switching circuit for producing the transmitting signal;
a receiving circuit connected to the transmitting and receiving switching circuit for receiving the receiving signal;
a transmitting and receiving switching circuit connected to the first through N-th impedance matching circuits and to the transmitting and receiving circuits for connecting, in response to transmitting and receiving switching control signals, the first through N-th impedance matching circuits to one of the transmitting and receiving circuits;
a controlling unit connected to the level detecting circuit, to the switching circuit, to the transmitting and receiving switching circuit, and to the transmitting and receiving circuits for producing and supplying the transmitting and receiving switching control signals to the transmitting and receiving switching circuit, respectively;
a human body contact discriminating circuit connected to the controlling unit for discriminating whether or not a human body is contact with the movable radio terminal device to produce and supply a human body contact discriminating signal to the controlling unit when the human body is contact with the movable radio terminal device; and
a memory device connected to the controlling unit;
the controlling unit producing and supplying the first matching switching control signal to the switching circuit when the controlling unit is not supplied with the human body contact discriminating signal from the human body contact discriminating circuit, the controlling unit producing and supplying, at every predetermined time interval, the first through N-th matching switching control signals to the switching circuit, respectively, to make the memory device memorize, as first through N-th level signals having first through N-th level values, the detected level signals from the level detecting circuit when the switching circuit connects the antenna to the first through N-th impedance matching circuits, respectively, and when the controlling unit is supplied with the human body contact discriminating signal from the human body contact discriminating circuit, the controlling unit selecting, as a selected level value, one of the first through N-th level values that is greatest in the first through N-th level values, the controlling unit producing and supplying one of the first through N-th matching switching control signals that corresponds to the selected level value to the switching circuit.
According to a second aspect of this invention, there is provided a movable radio terminal device comprising:
an antenna receiving a radio receiving signal to produce a receiving signal, the antenna receiving a transmitting signal to produce a radio transmitting signal;
a level detecting circuit connected to the antenna for detecting a level of one of the receiving signal and the transmitting signal to produce a detected level signal having a detected level value;
first through N-th impedance matching circuits having first through N-th impedances which are different, where N represents an integer greater than one;
a switching circuit connected to the antenna and to the first through N-th impedance matching circuits for connecting, in response to one of first through N-th matching switching control signals, the antenna to one of the first through N-th impedance matching circuits;
a transmitting circuit connected to the transmitting and receiving switching circuit for producing the transmitting signal;
a receiving circuit connected to the transmitting and receiving switching circuit for receiving the receiving signal;
a transmitting and receiving switching circuit connected to the first through N-th impedance matching circuits and to the transmitting and receiving c
Hosonuma Yoshimasa
Tanaka Masahiko
Hunter Daniel S.
NEC Corporation
Scully Scott Murphy & Presser
Zewdu Meless N
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