1. A communication apparatus comp(rriissiiin g: first communication means for transmitting differential signals 5 serving as first information over a first wire pair; second communication means for transmitting differential signals serving as second information over a second wire pair; and third communication means for transmitting third information by superimposing one of differential signals over the first wire pair and 10 superimposing the other of the differential signals over the second wire pair. 15 20 25 30

2. The communication apparatus according to Claim 2, wherein the third communication means transmits the third information in common mode by superimposing the one differential signal in such a manner that the one differential signal is in the same phase through both transmission paths forming the first wire pair and superimposing the other differential signal in such a manner that the other differential signal is in the same phase through both transmission paths forming the second wire pair.

3. The communication apparatus according to claim 1 or 2, wherein the first communication means receives differential signals serving as fourth information transmitted over the first wire pair, the second communication means receives differential signals serving as fifth information transmitted over the second wire pair, and the third communication means receives sixth information by receiving one of differential signals transmitted over the first wire pair and the other of the differential signals transmitted over the second wire pair.

4. A signal superimposing circuit comprising: a first superimposing circuit that superimposes differential signals and one of different differential signals over a first wire pair, and a second superimposing circuit that superimposes differential 07 FEB signals and the other of the different differential signals over a second wire pair.

5. The signal superimposing circuit according to Claim 4, wherein 5 the first superimposing circuit superimposes the one different differential signal in such a manner that the one different differential signal is in the same phase through both transmission paths forming the first wire pair, and the second superimposing circuit superimposes the other different 10 differential signal in such a manner that the other different differential signal is in the same phase through both transmission paths forming the second wire pair.

6. The signal superimposing circuit according to Claim 4 or 5, 15 further comprising: first input means for receiving first differential signals; second input means for receiving second differential signals; and third input means for receiving third differential signals, wherein the first superimposing circuit superimposes the first differential 20 signals received by the first input means and one of the third differential signals received by the third input means over the first wire pair, and the second superimposing circuit superimposes the second differential signals received by the second input means and the other third differential signal over the second wire pair. 25 30

7. The signal superimposing circuit according to Claim 6, further comprising a phase delay circuit that delays phases of the third differential signals, wherein the first superimposing circuit superimposes one of the third differential signals phase-delayed by the phase delay circuit over the first wire pair, and the second superimposing circuit superimposes the other third differential signal phase-delayed by the phase adjustment circuit over the ORIGINAL 01 FEB MU 24 second wire pair. flO 955*14

8. The signal superimposing circuit according to any one of Claims 4 to 7, wherein the first and second superimposing circuits superimpose 5 signals so that a sum of vectors of the signals passing through the first and second wire pairs is zero. 10 15 20

9. A method for superimposing signals, comprising: transmitting first differential signals over a first wire pair; transmitting second differential signals over a second wire pair; and superimposing one of third differential signals over the first wire pair and superimposing the other third differential signal over the second wire pair. Dated this 7r't"h day of February 2014 Of Anand and Anana Advocates Agent for the Applicant

DESCRIPTION
COMMUNICATION APPARATUS, SIGNAL SUPERIMPOSING
CIRCUIT, AND METHOD FOR SUPERIMPOSING SIGNALS
5
Technical Field
[0001]
The present invention relates to a communication apparatus for
transmitting signals using multiple wire pairs, a signal superimposing
10 circuit for superimposing multiple signals, and a method for
superimposing signals.
Background Art
[0002]
Inter-apparatus communications conforming to the
15 communication standard 100 BASE-TX or 1000 BASE-T have been widely
used. Known methods for controlling an apparatus that performs
inter-apparatus communications include disposition of input/output
terminals for control and transmission of control signals over main lines.
[0003]
20 However, the disposition of input/output terminals for control
increases the cost, as well as requires space for disposing the
input/output terminals. Further, the transmission of control signals over
main lines reduces the capacity of the main lines.
[0004]
25 Technologies for solving these problems include a transmission
system disclosed in Patent Literature 1. In the transmission system of
Patent Literature 1, common-mode signals are transmitted over a
Ethernet® pair wire. Thus, control signals are transmitted without
having to dispose input/output terminals for control and without reducing
30 the capacity of the main lines. Since this configuration allows
common-mode signals to be transmitted over each wire of the twisted pair,
the communication capacity can be increased.
Citation List
Patent Literature
[0005]
[Patent Literature 1] Published Japanese Translation of PCT International
Publication for Patent Application, No. 2008-521342
Summary of Invention
Technical Problem
[0006]
However, in the transmission system of Patent Literature 1, noise
10 around the wires is input to each wire as common mode noise, and thus the
transmitted common-mode signals are subject to the noise. Further,
since the transmission system of Patent Literature 1 allows common-mode
signals to be transmitted over the wires, each wire generates a magnetic
field in the same direction, thereby causing spurious emission where each
15 wire acts as an antenna.
[0007]
The present invention has been made in view of the above problems,
and an object thereof is to provide a communication apparatus, signal
superimposing circuit, and method for superimposing signals which can
20 transmit signals in such a manner that the signals are not easily subject to
noise and that spurious emission is suppressed.
Solution to Problem
[0008]
A first exemplary aspect of the present invention is a
25 communication apparatus comprising: a first communication unit that
transmits differential signals serving as first information over a first wire
pair; a second communication unit that transmits differential signals
serving as second information over a second wire pair; and a third
communication unit that transmits third information by superimposing
30 one of differential signals over the first wire pair and superimposing the
other of the differential signals over the second wire pair.
[0009]
A second exemplary aspect of the present invention is a signal
superimposing circuit comprising: a first superimposing circuit that
superimposes differential signals and one of different differential signals
over a first wire pair, and a second superimposing circuit that
superimposes differential signals and the other of the different
differential signals over a second wire pair.
5 [0010]
A third exemplary aspect of the present invention is a method for
superimposing signals, comprising: transmitting first differential signals
over a first wire pair; transmitting second differential signals over a
second wire pair; and superimposing one of third differential signals over
10 the first wire pair and superimposing the other third differential signal
over the second wire pair.
Advantageous Effects of Invention
[0011]
15 According to the present invention, it is possible to provide a
communication apparatus, signal superimposing circuit, and method for
superimposing signals which can transmit signals in such a manner that
the signals are not easily subject to noise and that spurious emission is
suppressed.
20 Brief Description of Drawings
[0012]
Fig. 1 is a diagram showing a configuration of a transmission
system according to a first embodiment.
Fig. 2 is a conceptual diagram showing an aspect of signal
25 transmission in the transmission system according to the first
embodiment.
Fig. 3 is a conceptual diagram showing an aspect of signal
transmission in the transmission system according to the first
embodiment.
30 Fig. 4A is a diagram showing an example of the waveforms of
signals which have j u s t been input to a communication apparatus 10 in the
transmission system according to the first embodiment.
Fig. 4B is a diagram showing an example of the waveforms of
signals which have just passed through a phase adjustment circuit 12A in
the transmission system according to the first embodiment.
Fig. 4C is a diagram showing an example of the waveforms of
signals which are passing through a twisted pair wire in the transmission
system according to the first embodiment.
5 Fig. 4D is a diagram showing an example of the waveforms of
signals which have just been output from superimposing coils 21A and
21B in the transmission system according to the first embodiment.
Fig. 4E is a diagram showing an example of the waveforms of
signals which have just passed through a phase adjustment circuit 22A in
10 the transmission system according to the first embodiment.
Fig. 5A is a diagram showing another example of the waveforms of
signals which have just been input to the communication apparatus 10 in
the transmission system according to the first embodiment.
Fig. 5B is a diagram showing another example of the waveforms of
15 signals which are passing through the twisted pair wire in the
transmission system according to the first embodiment.
Fig. 5C is a diagram showing another example of the waveforms of
signals which have just been output from the superimposing coils 21A
and 21B in the transmission system according to the first embodiment.
20 Fig. 6 is a diagram showing a configuration of the transmission
system according to the first embodiment of the present invention.
FIG. 7 is a block diagram showing a configuration of a signal
superimposing circuit according to the first embodiment.
FIG. 8 is a block diagram showing another configuration of the
25 signal superimposing circuit according to the first embodiment.
Fig. 9 is a diagram showing a configuration of the communication
apparatus according to the first embodiment.
Fig. 10 is a diagram showing a configuration of a modification of
the communication apparatus according to the first embodiment.
30 Description of Embodiments
[0013]
Now, an embodiment of the present invention will be described
with reference to the drawings. While the embodiment of the present
invention described below is preferred, the scope of the invention is not
limited thereto. In the following description, components having
similar reference signs operate in substantially the same manner.
[0014]
First Embodiment
5 Now, an embodiment of the present invention will be described
with reference to the drawings. Fig. 1 is a diagram showing a
configuration of a transmission system according to the present invention.
In the transmission system according to the present invention, a
communication apparatus 10 and a communication apparatus 20 are
10 connected together through four twisted pair wires 30A to 30D. Each
twisted pair wire is a wire formed by stranding two transmission wires.
[0015]
The communication apparatus 10 includes superimposing coils l l A,
I I B , l i e , and I ID and phase adjustment circuits 12A and 12B. The
15 communication apparatus 10 outputs signals received from four main
lines and two control lines to the twisted pair wires 30A, 30B, 30C, and
30D. The communication apparatus 10 also outputs signals received
from the four twisted pair wires 30A, 30B, 30C, and 30D to the four main
lines and two control lines.
20 [0016]
Similarly, the communication apparatus 20 includes superimposing
coils 21A, 21B, 21C, and 21D and phase adjustment circuits 22A and 22B.
The communication apparatus 20 outputs signals received from four main
lines and two control lines to the twisted pair wires 30A, 30B, 30C, and
25 30D. The communication apparatus 20 also outputs signals received
from the four twisted pair wires 30A, 30B, 30C, and 30D to the four main
lines and two control lines.
[0017]
The phase adjustment circuits 12A and 12B included in the
30 communication apparatus 10 each include two pairs of input/output
terminals (four terminals). Each phase adjustment circuit receives
differential signals at one pair of terminals and outputs
1/2-phase-delayed differential signals from the other pair of terminals.
That is, the phase adjustment circuits 12A and 12B phase-delay the
7
received differential signals by 1/2 phase and output the phase-delayed
differential signals.
[0018]
For the phase adjustment circuit 12A, one pair of input/output
5 terminals thereof is connected to the control line 1; one terminal of the
other pair of input/output terminals thereof is connected to the
superimposing coil l l A ; and the other terminal of the other pair of
input/output terminals is connected to the superimposing coil IIB.
Similarly, for the phase adjustment circuit 12B, one pair of input/output
10 terminals thereof is connected to the control line 2; one terminal of the
other pair of input/output terminals is connected to the superimposing
coil IIC; and the other terminal of the other pair of input/output
terminals is connected to the superimposing coil IID.
[0019]
15 The superimposing coils l l A , I I B , I I C , and IID included in the
communication apparatus 10 each include two pairs of differential
input/output terminals (four terminals) and one common-mode
input/output terminal. The common-mode input/output terminals of the
superimposing coils l l A , I I B , I I C , and I ID are connected to the twisted
20 pair wires 30A, SOB, 30C, and 30D, respectively.
[0020]
In each superimposing coil, the pairs of differential input/output
terminals are insulated from each other. While differential signals pass
between the pairs, common-mode signals do not pass therebetween. As
25 used herein, a common-mode signal refers to a signal which is propagated
through two transmission paths in the same phase. Each superimposing
coil receives differential signals at one pair of differential input/output
terminals and outputs the differential signals from the other pair of
differential input/output terminals.
30 [0021]
When the differential input/output terminals connected to the
common-mode input/output terminal receive common-mode signals, the
common-mode input/output terminal outputs signals having the same
waveform. When the common-mode input/output terminal receives
8
signals, it outputs signals having the same waveform to the differential
input/output terminals connected thereto.
[0022]
Next, the respective operations of the main lines and control lines
5 of the transmission system of the present embodiment will be described
and then superimposed signals will be described. While the number of
pairs of input differential signals can be any number greater than or equal
to three in the present invention, the control line 1 and the main lines 1
and 2 will be selectively described.
10 [0023]
First, referring to Fig. 2, main line-to-main line transmission will
be described. Fig. 2 shows an aspect where differential signals input to
the main line 1 connected to the communication apparatus 10 are output
through the twisted pair wire 30A to the main line 1 connected to the
15 communication apparatus 20. Differential signals input from the main
line 1 to the communication apparatus 10 are input to the superimposing
coil l l A , which then outputs differential signals having the same
waveform to the twisted pair wire 30A. The differential signals are
input through the twisted pair wire 30A to the communication apparatus
20 20, which then inputs the differential signals to the superimposing coil
21A, which then outputs differential signals having the same waveform to
the main line. Similarly, signals are transmitted from each main line
connected to the communication apparatus 20 to each main line connected
to the communication apparatus 10.
25 [0024]
Next, referring to Fig. 3, control line-to-control line transmission
will be described. Differential signals input from the control line 1 to
the communication apparatus 10 are input to the phase adjustment circuit
12A and phase-adjusted. The phase adjustment circuit 12A
30 phase-adjusts the input differential signals so that the signals are delayed
by 1/2 phase, outputs one of the phase-adjusted differential signals to the
common-mode input/output terminal of the superimposing coil 11 A, and
outputs the other phase-adjusted differential signal to the common-mode
input/output terminal of the superimposing coil IIB.
[0025]
The signal input from the phase adjustment circuit 12A to the
superimposing coil l l A becomes a common-mode signal and is output
from the differential input/output terminal adjacent to the common-mode
5 input/output terminal to the twisted pair wire 30A. Similarly, the signal
input from the phase adjustment circuit 12A to the superimposing coil
I IB becomes a common-mode signal and is output from the differential
input/output terminal adjacent to the common-mode input/output terminal
to the twisted pair wire 30B. At this time, the common-mode signals
10 having opposite phases pass through the twisted pair wires 30A and 308.
For this reason, magnetic fields generated by the wires are cancelled out,
thus suppressing spurious emission based on the common-mode signals.
[0026]
The common-mode signal which has passed through the twisted
15 pair wire 30A is input to the superimposing coil 21A of the
communication apparatus 20. The superimposing coil 21A outputs, as
one of differential signals, the input common-mode signal having the
same waveform from the common-mode input/output terminal to the phase
adjustment circuit 22A. The common-mode signal which has passed
20 through the twisted pair wire 30B is input to the superimposing coil 21B
of the communication apparatus 20. The superimposing coil 21B outputs,
as the other differential signal, the input common-mode signal having the
same waveform from the common-mode input/output terminal to the phase
adjustment circuit 22A. In this way, the two common-mode signals,
25 which have been transmitted over the twisted pair wires 30A and 30B and
satisfy an opposite phase relationship, are extracted as signals forming
differential signals.
[0027]
The differential signals input from the superimposing coils 21A
30 and 21B to the phase adjustment circuit 22A are delayed by 1/2 phase and
synchronized with differential signals over the main lines, and then
output to the control line. In this way, the signals are transmitted from
the control line connected to the communication apparatus 10 to the
control line connected to the communication apparatus 20. Similarly,
10
signals are transmitted from the control line connected to the
communication apparatus 20 to the control line connected to the
communication apparatus 10.
[0028]
5 Next, referring to Figs. 4A to 4E, superimposed signals will be
described. Fig. 4A shows the waveforms of signals input from the
control line 1 and the main lines 1 and 2 to the communication apparatus
10. The differential signals input from the control line 1 and the main
lines 1 and 2 are synchronized with one another. Fig. 4B shows signals
10 which have just passed through the phase adjustment circuit 12A. Since
the signals over the control line have a 1/2-phase-delayed waveform due
to the passage of these signals through the phase adjustment circuit 12A,
the transition timing of the signals over the control line and the transition
timing of the signals over the main lines 1 and 2 are shifted from each
15 other. The necessity for shifting the transition timings of the signals
from each other will be described later. Fig. 4C shows the waveforms of
signals over the twisted pair wires 30A and SOB which have just passed
through the superimposing coils l lA and I I B . At this time, the sum of
the vectors of all the waveforms is zero. Fig. 4D shows outputs from the
20 superimposing coils 21A and 21B. At this time, the waveforms of the
signals over the respective lines are restored, while the waveforms of the
signals over the control line 1 are delayed by 1/2 phase. Fig. 4E shows
outputs from the superimposing coil 22A. Since the phase adjustment
circuit 22A delays the signals over the control line 1 by 1/2 phase, these
25 signals are behind the signals over the main lines 1 and 2 by one phase
and synchronized therewith.
[0029]
Next, referring to Figs. 5A to 5C, the functions of the phase
adjustment circuit will be described. Fig. 5A shows the waveforms of
30 the signals input from the control line 1 and the main lines 1 and 2 to the
communication apparatus 10. These waveforms are the same as those in
Fig 4A. If the signals having these waveforms are input to the
superimposing coils l l A and I IB without passing through the phase
adjustment circuit 12A, signals output from the superimposing coils to
11
the twisted pair wires 30A and BOB take waveforms shown in Fig. 5B
When the signals having these waveforms are input through the twisted
pair wires 30A and 30B to the superimposing coils 21A and 21B, portions
which cannot be divided occur in the waveforms of the signals over the
5 main lines and the waveforms of the signals over the control line, as
shown in Fig. 5C. As seen above, transmission of signals in
synchronization with one another and having similar frequency
components requires a mechanism which shifts the transition timings of
the differential signals and common-mode signal from each other. For
10 this reason, using the ph&se adjustment circuit, the transmission side
phase-delays the differential signals received from the control line
compared to the differential signals received from the main lines and then
superimposes the signals. Thus, the receiving side can properly separate
the signals.
15 [0030]
Note that if the signals over the control line are sufficiently slow
compared to the signals over the main lines, the superimposing coils can
separate the signals. Thus, the phase adjustment circuit becomes
unnecessary. In this case, as shown in Fig. 6, the signals can be
20 superimposed without having to phase-adjust the signals using a phase
adjustment circuit. Specifically, the superimposing coil l lA serving as
a first superimposing circuit superimposes the differential signals
received from the main line 1 and one of different differential signals
received from the control line over the twisted pair wire 30A serving as a
25 first wire pair. Similarly, the superimposing coil I IB serving as a
second superimposing circuit superimposes the differential signals
received from the main line 2 and the other different differential signal
received from the control line over the twisted pair wire 30B serving as a
second wire pair. In this way, the communication apparatus 10
30 superimposes the signals and transmits the superimposed signals over the
twisted pair wires 30A and 30B. In this case, the superimposing coil
l lA serving as a first superimposing circuit superimposes the one
different differential signal received from the control line so that the
signal is transmitted as a common-mode signal over both transmission
12
paths forming the twisted pair wire 30A. Similarly, the superimposing
coil I IB serving as a second superimposing circuit superimposes the
other different differential signal so that the signal is transmitted as a
common-mode signal over both transmission paths forming the twisted
5 pair wire 30B. Accordingly, the sum of the vectors of the four
transmission paths forming the twisted pair wires 30A and 30B becomes
zero. As a result, magnetic fields generated by the wires can be
cancelled out, thereby suppressing spurious emission. Further, the
receiving side, communication apparatus 20, can properly separate the
10 common-mode signals and the differential signals. According to the
present invention, the above configuration is possible.
[0031]
As described above, according to the present invention, the
communication apparatus, which is configured to transmit differential
15 signals over the wire pairs, superimposes signals having a predetermined
phase over a wire pair for transmitting first differential signals and
superimposes signals having an opposite phase over a wire pair for
transmitting second differential signals. That is, as like in the case of
one and the other of differential signals, the signals superimposed over
20 the first wire pair and the signals superimposed over the second wire pair
satisfy an opposite phase relationship. According to this configuration,
it is possible to suppress spurious radio emission resulting from the
transmission of common-mode signals over the transmission paths and to
increase the communication capacity without having to increase the
25 number of wires. Further, although the signals input from the control
line as differential signals are transmitted over the twisted pair wire as
common-mode signals, the signals are extracted as differential signals on
the receiving side. Thus, the resistance to noise can be improved. That
is, since noise generated by the wires is output from the control line in
30 common mode, it is possible to easily separate and eliminate the noise
from the differential signals over the control line. Further, according to
this configuration, it is possible to increase the communication capacity
without having to tailor the existing wires. As a result, it is possible to
reduce the wiring cost for increasing the communication capacity.
13
[0032]
While the configuration where the signals are delayed by 1/2
phase by the phase adjustment circuit 12A on the transmission side and
then delayed by another 1/2 phase by the phase adjustment circuit 22A on
5 the receiving side and thus delayed by a total of one delay has been
described, other configurations may be employed. For example, a
configuration where the signals are delayed by 1/4 phase by the phase
adjustment circuit 12A and then delayed by 3/4 phase by the phase
adjustment circuit 22A and thus delayed by a total of one phase and then
10 separated, may be employed.
[0033]
Fig. 7 is a block diagram of a signal superimposing circuit for
superimposing signals in the communication apparatus described above.
A signal superimposing circuit 100 includes the phase adjustment circuit
15 12A, input/output terminals 13A to 13C, input/output terminals 14A and
14B, and superimposing circuits llOA and llOB.
[0034]
The input/output terminals 13A to 13C receive first to third
differential signals from lines 1 to 3, respectively. Each line is a wire
20 pair composed of two transmission paths. The differential signals
received by the input/output terminals 13A to 13C are directly output to
the superimposing circuits llOA and llOB and the phase adjustment
circuit 12A, respectively.
[0035]
25 The input/output terminals 13A to 13C also receive differential
signals directly from the superimposing circuits llOA and llOB and the
phase adjustment circuit 12A, respectively, and output the differential
signals directly to the lines 1 to 3.
[0036]
30 The phase adjustment circuit 12A phase-delays the differential
signals received from the input/output terminals 13C by a predetermined
amount of phase, outputs one of the phase-delayed differential signals to
the superimposing circuit llOA, and outputs the other phase-delayed
differential signal to the superimposing circuit llOB. The signals
14
output to the superimposing circuits llOA and llOB are one and the other
of the differential signals which have been received and phase-delayed by
the phase adjustment circuit 12A, and therefore satisfy an opposite phase
relationship.
5 [0037]
The phase adjustment circuit 12A also phase-delays the signal
received from the superimposing circuit llOA and the signal received
from the superimposing circuit llOB by the same amount of phase and
outputs the two phase-delayed signals to the input/output terminals 13C
10 as differential signals. The two signals received from the superimposing
circuits llOA and HOB by the phase adjustment circuit 12A satisfy an
opposite phase relationship. Accordingly, a combination of the two
signals can become differential signals.
[0038]
15 The superimposing circuit llOA superimposes the signal received
from the phase adjustment circuit 12A on the differential signals received
from the input/output terminals 13A and then outputs the superimposed
signals to the input/output terminal 14A. That is, the superimposing
circuit llOA outputs the differential signals received from the
20 input/output terminals 13A as they are, while it outputs the signal
received from the phase adjustment circuit 12A to the transmission paths
forming the wire pair as a common-mode signal in such a manner that the
signal is in the same phase through the transmission paths. As a result,
the superimposing circuit llOA outputs the signals where the
25 common-mode signal is superimposed on the differential signals.
[0039]
Further, the superimposing circuit llOA splits the signal received
from the input/output terminals 14A into in-phase components and
differential components, outputs differential signals to the input/output
30 terminals 13A, and outputs common-mode signal components to the phase
adjustment circuit 12A.
[0040]
The superimposing circuit llOB superimposes the signal received
from the phase adjustment circuit 12A on the differential signals received
15
from the input/output terminals 13B and then outputs the superimposed
signals to the input/output terminal 14B. Accordingly, the
superimposing circuit llOB outputs the differential signals received from
the input/output terminals 13B, as they are, while it outputs, as a
5 common-mode signal, the signal received from the phase adjustment
circuit 12A to the input/output terminals 14B in such a manner that the
signal is in the same phase through the transmission paths forming the
wire pair. As a result, the superimposing circuit llOB outputs the
signals where the common-mode signal is superimposed on the
10 differential signals.
[0041]
The superimposing circuit llOB also splits the signal received
from the input/output terminals 14B into in-phase components and
differential components, outputs differential signals to the input/output
15 terminals 13B, and outputs common-mode signal components to the phase
adjustment circuit 12A.
[0042]
The superimposing circuits llOA and llOB correspond to the
superimposing coils l lA and I I B , respectively, of Fig. 1. The
20 common-mode signals input to or output from the superimposing circuits
llOA and llOB are signals which satisfy an opposite phase relationship,
as described above. The common-mode signals are input to the
differential input terminals of the superimposing circuit 11 A and become
differential signals.
25 [0043]
The input/output terminals 14A output the signals received from
the superimposing circuit llOA to a first twisted pair wire or output the
signals received from the twisted pair wire to the superimposing circuit
llOA. The input/output terminals 14B output the signals received from
30 the superimposing circuit llOB to a second twisted pair wire or output the
signals received from the twisted pair wire to the superimposing circuit
llOB. The superimposed differential signals and common-mode signal
are transmitted over each twisted pair wire.
[0044]
16
The signal superimposing circuit 100 may be configured as shown
in Fig. 8. In this configuration, phase adjustment circuits 12A and 12B
are disposed between the input/output terminals 13A and 13B and the
superimposing circuits llOA and llOB, respectively. That is, the phase
5 adjustment circuit 12A phase-delays differential signals received from
the input/output terminals 13A by a predetermined amount of phase and
outputs the phase-delayed differential signals to the superimposing
circuit llOA. Similarly, the phase adjustment circuit 12B phase-delays
differential signals received from the input/output terminals 13B by a
10 predetermined amount of phase and outputs the phase-delayed differential
signals to the superimposing circuit llOB.
[0045]
In this configuration also, each superimposing circuit can
superimpose the differential signals and the common-mode signal in such
15 a manner as to make a phase difference. Thus, the receiving side can
properly separate the signals.
[0046]
The communication apparatus of the present invention may be
configured as shown in Fig. 9. In Fig. 9, a communication apparatus 40
20 includes a first communication unit 41A, a second communication unit
41B, and a third communication unit 41C.
[0047]
The first communication unit 41A transmits differential signals
serving as first information over the twisted pair wire 30A serving as a
25 first wire pair.
[0048]
The second communication unit 41B transmits differential signals
serving as second information over the twisted pair wire 30B serving as a
second wire pair.
30 [0049]
The third communication unit 41C transmits third information by
superimposing one of differential signals over the twisted pair wire 30A
and superimposing the other differential signal over the twisted pair wire
30B.
17
[0050]
At this time, the first communication unit 41A transmits the third
information by transmitting the one differential signal over the
transmission paths forming the twisted pair wire 30A in such a manner
5 that the one differential signal is in the same phase through the
transmission p a t h s a n d transmitting the other differential signal over the
transmission paths forming the twisted pair wire 30B in such a manner
that the other differential signal is in the same phase through the
transmission paths.
10 [0051]
The third communication unit 41C transmits the third information
at a shifted transmission timing. Specifically, the third communication
unit 41C phase-adjusts the signals to be transmitted by a predetermined
amount of phase using an internal phase adjustment circuit and then
15 transmits the signals. Accordingly, while the signals to be transmitted
from the first communication unit 41A and the signals to be transmitted
from the second communication unit 41B are transmitted at the same
timing, the signals to be transmitted from the third communication unit
41C are transmitted at the shifted transmission timing. As a result, the
20 receiving-side communication apparatus can properly separate the
signals.
[0052]
As shown in Fig. 10, a phase adjustment unit 42 for
phase-adjusting signals to be transmitted may be disposed outside the
25 third communication unit 41C.
[0053]
While the configuration where six pairs of differential signals
are received from the four main lines and two control lines have been
described, other configurations may be employed. The number of pairs
30 of differential signals received by the communication apparatus of the
present invention may be any number greater than or equal to three.
[0054]
The present invention is not limited to the above embodiment, and
changes can be made to the embodiment as appropriate without departing
18
from the spirit and scope of the invention. For example, the following
configuration is possible.
[0055]
(1) A communication apparatus comprising: first communication
5 means for transmitting differential signals serving as first information
over a first wire pair; second communication means for transmitting
differential signals serving as second information over a second wire
pair; and third communication means for transmitting third information
by superimposing one of differential signals over the first wire pair and
10 superimposing the other of the differential signals over the second wire
pair.
(2) The communication apparatus according to (2), wherein the
third communication means transmits the third information in common
mode by superimposing the one differential signal in such a manner that
15 the one differential signal is in the same phase through both transmission
paths forming the first wire pair and superimposing the other differential
signal in such a manner that the other differential signal is in the same
phase through both transmission paths forming the second wire pair.
(3) The communication apparatus according to (1) or (2), wherein
20 the first communication means receives differential signals serving as
fourth information transmitted over the first wire pair, the second
communication means receives differential signals serving as fifth
information transmitted over the second wire pair, and the third
communication means receives sixth information by receiving one of
25 differential signals transmitted over the first wire pair and the other of
the differential signals transmitted over the second wire pair.
(4) A signal superimposing circuit comprising: a first
superimposing circuit that superimposes differential signals and one of
different differential signals over a first wire pair, and a second
30 superimposing circuit that superimposes differential signals and the other
of the different differential signals over a second wire pair.
(5) The signal superimposing circuit according to (4), wherein the
first superimposing circuit superimposes the one different differential
signal in such a manner that the one different differential signal is in the
19
same phase through both transmission paths forming the first wire pair,
and the second superimposing circuit superimposes the other different
differential signal in such a manner that the other different differential
signal is in the same phase through both transmission paths forming the
5 second wire pair.
(6) The signal superimposing circuit according to (4) or (5),
further comprising: first input means for receiving first differential
signals; second input means for receiving second differential signals; and
third input means for receiving third differential signals, wherein the
10 first superimposing circuit superimposes the first differential signals
received by the first input means and one of the third differential signals
received by the third input means over the first wire pair, and the second
superimposing circuit superimposes the second differential signals
received by the second input means and the other third differential signal
15 over the second wire pair.
(7) The signal superimposing circuit according to (6), further
comprising a phase delay circuit configured to delay phases of the third
differential signals, wherein the first superimposing circuit superimposes
one of the third differential signals phase-delayed by the phase delay
20 circuit over the first wire pair, and the second superimposing circuit
superimposes the other third differential signal phase-delayed by the
phase adjustment circuit over the second wire pair.
(8) The signal superimposing circuit according to any one of (4) to
(7), wherein the first and second superimposing circuits superimpose
25 signals so that a sum of vectors of the signals passing through the first
and second wire pairs is zero.
(9) A method for superimposing signals, comprising: transmitting
• first differential signals over a first wire pair; transmitting second
differential signals over a second wire pair; and transmitting one of third
30 differential signals over the first wire pair and transmitting the other
third differential signal over the second wire pair.
(10) The signal superimposing circuit according to (6), wherein the
first superimposing circuit splits a signal received from the first wire pair
into differential signal components and common-mode signal components.
20
outputs the differential signal components to the first input unit, and
outputs the common-mode signal components to the third input unit, the
second superimposing circuit splits a signal received from the second
wire pair into differential signal components and common-mode signal
5 components, outputs the differential signal components to the second
input unit, and outputs the common-mode signal components to the third
input unit, the first input unit outputs the differential signal received
from the first superimposing circuit as fourth differential signals, the
second input unit outputs the differential signal components received
10 from the second superimposing circuit as fifth differential signals, and
the third input unit superimposes the common-mode signal components
received from the first superimposing circuit and the common-mode
signal components received from the second superimposing circuit and
outputs the superimposed signals as sixth differential signals.
15 [0056]
While the invention of the present application has been described
with reference to the embodiment, the invention is not limited thereto.
Various changes understandable for those skilled in the art can be made to
the configuration or details of the invention of the present application
20 without departing from the scope of the invention.
[0057]
The present application claims priority based on Japanese Patent
Application No. 2011-181854, filed on Aug. 23, 2011, the disclosure of
which is incorporated herein in its entirety.
25 Reference Signs List
[0058]
10: communication apparatus
l lA to IID: superimposing coil
12A, 12B: phase adjustment circuit
30 13A to 13C: input/output terminals
14A, 14B: input/output terminals
20: communication apparatus
21A to 21D: superimposing coil
22A, 22B: phase adjustment circuit
21
30A to 30D: twisted pair wire
40: communication apparatus
41A to 41C: communication unit
42: phase adjustment unit
100: signal superimposing circuit
llOA, llOB: superimposing circuit

ORIGINAL
22 01 ftB MW
WE CLAIM: no 955.M
1. A communication apparatus comp(rriissiiin g:
first communication means for transmitting differential signals
5 serving as first information over a first wire pair;
second communication means for transmitting differential signals
serving as second information over a second wire pair; and
third communication means for transmitting third information by
superimposing one of differential signals over the first wire pair and
10 superimposing the other of the differential signals over the second wire
pair.
15
20
25
30
2. The communication apparatus according to Claim 2, wherein the
third communication means transmits the third information in common
mode by superimposing the one differential signal in such a manner that
the one differential signal is in the same phase through both transmission
paths forming the first wire pair and superimposing the other differential
signal in such a manner that the other differential signal is in the same
phase through both transmission paths forming the second wire pair.
3. The communication apparatus according to claim 1 or 2, wherein
the first communication means receives differential signals serving
as fourth information transmitted over the first wire pair,
the second communication means receives differential signals
serving as fifth information transmitted over the second wire pair, and
the third communication means receives sixth information by
receiving one of differential signals transmitted over the first wire pair
and the other of the differential signals transmitted over the second wire
pair.
4. A signal superimposing circuit comprising:
a first superimposing circuit that superimposes differential signals
and one of different differential signals over a first wire pair, and
a second superimposing circuit that superimposes differential
07 FEB
signals and the other of the different differential signals over a second
wire pair.
5. The signal superimposing circuit according to Claim 4, wherein
5 the first superimposing circuit superimposes the one different
differential signal in such a manner that the one different differential
signal is in the same phase through both transmission paths forming the
first wire pair, and
the second superimposing circuit superimposes the other different
10 differential signal in such a manner that the other different differential
signal is in the same phase through both transmission paths forming the
second wire pair.
6. The signal superimposing circuit according to Claim 4 or 5,
15 further comprising:
first input means for receiving first differential signals;
second input means for receiving second differential signals; and
third input means for receiving third differential signals, wherein
the first superimposing circuit superimposes the first differential
20 signals received by the first input means and one of the third differential
signals received by the third input means over the first wire pair, and
the second superimposing circuit superimposes the second
differential signals received by the second input means and the other
third differential signal over the second wire pair.
25
30
7. The signal superimposing circuit according to Claim 6, further
comprising
a phase delay circuit that delays phases of the third differential
signals, wherein
the first superimposing circuit superimposes one of the third
differential signals phase-delayed by the phase delay circuit over the first
wire pair, and
the second superimposing circuit superimposes the other third
differential signal phase-delayed by the phase adjustment circuit over the
ORIGINAL 01 FEB MU
24
second wire pair. flO 955*14
8. The signal superimposing circuit according to any one of Claims
4 to 7, wherein the first and second superimposing circuits superimpose
5 signals so that a sum of vectors of the signals passing through the first
and second wire pairs is zero.
10
15
20
9. A method for superimposing signals, comprising:
transmitting first differential signals over a first wire pair;
transmitting second differential signals over a second wire pair;
and
superimposing one of third differential signals over the first wire
pair and superimposing the other third differential signal over the second
wire pair.
Dated this 7r't"h day of February 2014
Of Anand and Anana Advocates
Agent for the Applicant