JP2004072137

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DESCRIPTION JP2004072137
To realize a wire-saving audio system capable of easily connecting devices even when the
number of devices is large. SOLUTION: The respective devices are daisy-chain connected in
duplicate by an AP line and an S line starting from a master device. When slave device B is used
as a source of an audio signal output from a speaker, the audio signal generated by slave device
B and output to the S line on the upstream side (master device side) is amplifier device B,
amplifier device A, slave device A is sequentially relayed to the upstream S line of each device
and sent to the master device. The master device performs predetermined processing on the
audio signal received from the S line and outputs the processed signal to the AP line. The audio
signal output to the AP line is sequentially relayed to the AP line on the downstream side by the
slave device A and the amplifier device A, and is sent to the amplifier device A and the amplifier
device B. The amplifier device A and the amplifier device B amplify the received audio signal and
output it to a speaker connected to itself. [Selected figure] Figure 2
Signal transmission system and audio system
The present invention relates to a signal transmission system for transmitting a signal such as a
digital audio signal among a plurality of devices, and more particularly to a technique for
facilitating the construction of the signal transmission system. . [0002] For example, as a
technology for transmitting and receiving digital audio signals between a plurality of audio
devices constituting an audio system, an interface of IEC 60958 / EIAJ CP 1201 standard known
as S / PDIF or AES / EBU Systems that use audio signals for transmitting audio signals are widely
used. In a system using such an interface of the IEC 60958 / EIAJ CP 1201 standard, each device
constituting an audio system such as a sound processor device, an amplifier device, various
player devices, etc. uses a different cable for each one-on-one. It will connect. As described above,
a system using the interface of the IEC 60958 / EIAJ CP 1201 standard is used to connect a
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plurality of other devices to a specific device constituting an audio system. The following
problems occur because the form of connecting other apparatuses to the specific apparatus in
one-to-one correspondence, that is, the form of star connection is adopted. That is, the wiring
between devices is complicated and easily confused. Also, it is not possible to connect more than
the number of interface ports provided in a particular device to the particular device. Also, in an
audio system composed of a wide variety of devices such as players, tuners, equalizers,
amplifiers, phase controllers, etc., there are many cases where specific rules exist in the device
connection order, connection ports, etc. It is often accompanied by difficulty for a general user to
connect each apparatus appropriately. Therefore, an object of the present invention is to provide
a wire-saving signal transmission system that can easily connect devices even when the number
of devices is large. In order to achieve the above object, the present invention provides a plurality
of source devices for generating signals, an output device for outputting signals, and a master
device for performing signal processing. The signal transmission system for transmitting signals
between the devices of the present invention is daisy-chained to connect each device in duplicate
by two signal lines of the first system signal line and the second system signal line starting from
the master device. The master device is provided with signal processing means for subjecting the
signal received from the signal line of the first system to the signal processing of the first system
and transmitting it to the signal line of the second system. To the source device other than the
downstream end of the signal line of the first system with the upstream direction and the
opposite direction as the downstream direction, the upstream side receives the signal received
from the signal line of the first system downstream Uplink relay means for transmitting to the
first system signal line, generated signal transmitting means for transmitting the signal generated
by itself to the upstream first system signal line, and received from the upstream second system
signal line And downstream relay means for transmitting the signal to the downstream second
system signal line, wherein the output device other than the downstream end of the second
system signal line is received from the downstream first system signal line Upstream relay means
for transmitting an upstream signal to the first system signal line, and downstream relay means
for transmitting a signal received from the upstream second system signal line to the
downstream second system signal line And output means for outputting a signal received from
the signal line of the second system on the upstream side, and the source device, which is the
downstream end of the signal line of the first system, Signal line of the first system Output signal
transmitting means for transmitting to the output device, which is the downstream end of the
signal line of the second system, and output means for outputting the signal received from the
signal line of the second system upstream, It is a thing.
According to such a signal transmission system, the audio source device which is not the
downstream end of the signal line of the first system is provided with a control means, and in the
control means, at least the downstream side of the signal line of the first system. When the audio
source device of the present invention generates a digital audio signal to be output from the
audio output device, the upstream relay means receives the digital audio signal received from the
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signal line of the first stream downstream on the upstream side. The digital audio signal is
transmitted to the generated signal transmission means to the upstream first signal line when the
digital audio signal to be transmitted to the signal line of the signal line is generated at least
when the digital audio signal is output from the audio output device. To allow the first device to
connect to the master device from any source device. A signal is transmitted using the daisy
chain of in, the signal received from any source device is processed in the master, and the signal
as a processing result is transmitted to the output device using the daisy chain of the second line
Can be output. Therefore, the signal transmission system including a plurality of source devices
and output devices can be easily connected by daisy chaining the source devices and the output
devices sequentially without considering the connection order starting from the master device.
Can be built on. In addition, the configuration change and the like can be similarly easily
performed. Moreover, by adopting daisy chain connection, wiring can be reduced as compared
with the case of performing star type wiring. In addition, since the first line, which is a
transmission path used for transmitting a signal to the master device, and the signal line of the
second system, which is a transmission path used for transmitting a signal moving downstream
from the master device, are separately provided. The configuration for signal transmission of
each device can be simplified as compared with the case where bidirectional transmission of
signals is performed on the same signal line. Here, the signal is a digital audio signal, the source
device is an audio source device that generates a digital audio signal, the output device is an
audio output device that outputs a digital audio signal, and the master device is a digital signal. It
may be an apparatus that performs signal processing of an audio signal. Further, in this case, for
example, the audio source device includes a first signal port capable of connecting the first
system signal line and the second system signal line, the first system signal line, and the first
system signal line. A second signal port connectable to two signal lines, a signal generation unit
generating a digital audio signal, and a second signal line connected to the first signal port and
the second signal A first relay means for relaying digital audio signals to a second system signal
line connected to the port; and a first system signal line connected to the first signal port to the
second signal port Relay direction toward the first system signal line connected to the second
system, and from the first system signal line connected to the second signal port to the first
system signal line connected to the second signal port Direction One of the relay directions is
selected, and the first system signal line connected to the first signal port and the first system
signal line connected to the second signal port are selected. Second relay means for relaying the
digital audio signal in the selected relay direction, a first system signal line connected to the first
signal port, and a first system system connected to the second signal port Signal transmission
means for selecting one of the signal lines and transmitting the digital audio signal generated by
the signal generation unit to the selected first system signal line, and for relaying the digital
audio signal of the second relay means Presence or absence, selection of the relay direction of
the digital audio signal of the second relay means, presence or absence of transmission of the
digital audio signal of the signal transmission means, and a first system prior to the signal
transmission means It is preferable to configure and control means for controlling and No. line
selection.
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According to such a configuration, whichever of the first signal port and the second signal port is
on the upstream side can similarly be dealt with. Therefore, when connecting the first system
signal line and the second system signal line to the audio source device, it suffices to connect to
an available signal port, and it is necessary to consider which connection port should be
connected. There is no On the other hand, the audio output device comprises a first signal port
capable of connecting the first system signal line and the second system signal line, a first system
signal line and a second system signal line. A second signal port that can be connected, an audio
output unit that outputs a voice represented by a supplied digital audio signal, a first system
signal line connected to the first signal port, and the second signal port First relay means for
relaying digital audio signals to and from a first system signal line connected to the second
system, and a second system signal line connected to the first signal port to the second signal
port From the relay direction toward the connected second system signal line and from the
second system signal line connected to the second signal port to the second system signal line
connected to the second signal port One of the relay directions is selected, and the second system
signal line connected to the first signal port and the second system signal line connected to the
second signal port are selected. A second relay means for relaying digital audio signals in a
selected relay direction, a second system signal line connected to the first signal port, and a
second system connected to the second signal port Signal supplying means for selecting any one
of the signal lines and supplying a digital audio signal received by the selected second system
signal line to the audio output unit; and relaying of the digital audio signal of the second relay
means It is preferable to comprise control means for controlling selection of the direction and
selection of the signal line of the second system of the signal supply means. According to such a
configuration, whichever of the first signal port and the second signal port is on the upstream
side can similarly be dealt with. Therefore, when connecting the first system signal line and the
second system signal line to the audio output device, it is sufficient for the user to consider which
connection port should be connected if it is sufficient to connect to an available signal port.
There is no When the audio source apparatus is configured as described above, one end of the
second relay unit is connected to the signal line connection terminal of the first system of the
first port, and the other is connected to the other end. The first MOS FET to which the digital
audio signal input from the first system signal line connection terminal of the port is supplied,
and one end is connected to the first system signal line connection terminal of the second port,
and the other end is connected A digital audio signal input from the signal line connection
terminal of the first system of the first port is supplied with two MOS FETs, and the presence or
absence of relaying of the digital audio signal of the second relay means; Selection of the relay
direction of the digital audio signal of the second relay means is controlled by a combination of
on / off states of a first MOS FET and a second MOS FET The signal transmission means is
connected to the signal line connection terminal of the first system of the first port at one end,
and the other end is supplied with the digital audio signal generated by the signal generation unit
at the other end; A fourth MOS FET connected at one end to the signal line connection terminal
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of the first system of the second port and supplied with the digital audio signal generated by the
signal generation unit at the other end, the signal transmission Means for transmitting or not
transmitting the digital audio signal, and selecting the signal line of the first system of the signal
transmitting means, based on a combination of on / off states of the third MOS FET and the
fourth MOS FET. It is also preferable to be controlled.
According to this configuration, the internal circuit of the audio source device can be protected
from an overvoltage on the signal line of the first system by the MOS FETs, and these MOS FETs
are also used to switch the signal transmission path. Since this can be done, the device
configuration can be simplified. Further, also in the audio output apparatus, when the audio
output apparatus is configured as described above, one end of the second relay unit is connected
to the signal line connection terminal of the second system of the first port. Are connected, and
the other end of the first MOS FET to which the digital audio signal input from the second system
signal line connection terminal of the second port is supplied to the other end, and the second
system signal line connection terminal of the second port And a second MOS FET to which a
digital audio signal input from the signal line connection terminal of the second system of the
first port is supplied at the other end and the other end of the digital audio signal of the second
relay means The selection of the relay direction is controlled by the combination of the on / off
state of the first MOS FET and the second MOS FET, and the signal supply means is A third MOS
FET for outputting a digital audio signal which is connected at one end to the signal line
connection terminal of the second system of the first port and supplied to the audio output unit
from the other end, and a second of the second port A fourth MOS FET connected at one end to
the signal line connection terminal of the system and outputting a digital audio signal supplied
from the other end to the audio output unit; selection of the signal line of the second system of
the signal supply means Is preferably controlled by a combination of the on / off state of the
third MOS FET and the fourth MOS FET. In this way, the internal circuit of the audio output
device can be protected from overvoltage on the signal line of the first system by the MOS FET,
and these MOS FETs are also used to switch the signal transmission path. Thus, the apparatus
configuration can be simplified. BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter,
an embodiment of the present invention will be described by taking an application to an audio
system for transmitting digital audio signals between devices as an example. FIG. 1a shows an
example of the configuration of an audio system according to this embodiment. As shown, the
present audio system outputs audio to a single master device that is central to audio processing
in an audio system such as a digital sound processor, one or more slave devices that are sources
of audio signals, and a speaker. And one or more amplifier devices.
Each device is bus-connected by a CNT line that transmits a control signal, and the master device
is double-ended by two signal transmission lines of an AP line and an S line. It is connected in a
chain. Here, the connection order of each slave and each amplifier device on the daisy chain may
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be arbitrary. Hereinafter, in such an audio system, when viewed along a daisy chain composed of
an AP line and an S line, the direction to become the master device side will be described as the
upstream direction and the direction as the reverse side as the downstream direction. Do. Next,
FIG. 1 b shows another configuration example of the audio system according to the present
embodiment. As shown, this audio system doubles with the audio system of FIG. 1a with a master
device in common. Now, as devices constituting such an audio system, in the present
embodiment, each device is 1 port master, 2 port master, 1 port sub master, 2 port sub master, 1
port slave, 2 port slave, 1 Configure as port amplifier and 2 port amplifier. The 1-port master
(1M) is a master device capable of connecting only one set of AP line and S-line as shown in FIG.
1a, and the 2-port master (2M) is shown in FIG. 1b. Is a master device to which one or two sets of
AP lines and S lines can be connected. The 1-port sub-master (1SM) can also function as a master
device that can connect only one set of AP line and S line as shown in FIG. 1a, and downstream of
the daisy chain by AP line and S line It is a device that can also function as a slave device that can
be connected only to the side end. The two-port sub-master (2SM) can also function as a master
device shown in FIGS. 1a and 1b, and can be connected as a slave device that can be connected to
the middle or downstream end of the daisy chain by AP line and S line. Is also a device that can
function. The 1-port slave (1S) is a slave device that can be connected only to the downstream
end of the daisy chain by the AP line and the S line, and the 2-port slave (2S) is a daisy device by
the AP line and the S line. It is a slave device that can be connected to the middle of the chain as
well as to the downstream end. The one-port amplifier (1A) can be connected only to the
downstream end of the daisy chain by the AP line and the S line, and the two-port amplifier (2A)
is the daisy chain by the AP line and the S line Is an amplifier device that can be connected to
either the middle or the downstream end.
Next, the transmission path of the audio signal in the present audio system will be described.
FIGS. 2a and 2b show examples of the transmission path of the audio signal in the configuration
example shown in FIG. 1a. The transmission path shown in FIG. 2A is a transmission path when
the slave device B in the figure is used as a source of an audio signal output from a speaker, and
is generated by the slave device B and shown on the upstream side as shown in FIG. The audio
signal output to the S line is sequentially relayed to the S line upstream of each device by the
amplifier device B, the amplifier device A, and the slave device A, and is sent to the master device.
The master device performs predetermined processing (for example, equalization) on the audio
signal received from the S line, and outputs the result to the AP line. The audio signal output to
the AP line is sequentially relayed to the AP line on the downstream side by the slave device A
and the amplifier device A, and is sent to the amplifier device A and the amplifier device B. The
amplifier device A and the amplifier device B amplify the received audio signal and output it to a
speaker connected to itself. On the other hand, the transmission path shown in FIG. 2 b is a
transmission path in the case where the slave device A is the source of the audio signal output
from the speaker in the figure, and as shown in FIG. The audio signal generated by the above and
output to the upstream S line is sent to the master device. The master device performs
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predetermined processing on the audio signal received from the S line and outputs the processed
signal to the AP line. The audio signal output to the AP line is sequentially relayed to the AP line
on the downstream side by the slave device A and the amplifier device A, as in FIG. 1A, and sent
to the amplifier device A and the amplifier device B. The amplifier device A and the amplifier
device B amplify the audio signal received from the AP line on the upstream side, and output it to
a speaker connected to itself. As described above, according to the present embodiment, an audio
signal generated by an arbitrary slave device is transmitted to the master device simply by daisychaining the slave device and the amplifier device sequentially in an arbitrary order. At the same
time, the audio signal processed by the master device can be transmitted to each amplifier
device. Now, next, FIG. 2 c shows an example of the transmission path of the audio signal in the
configuration example shown in FIG. 1 b. The transmission path shown in FIG. 2c shows the
transmission path when the slave device B in the figure is used as the source of the audio signal
output from the speaker, and as shown in FIG. The audio signal output to the S line is
sequentially relayed to the S line upstream of each device by the amplifier device A and the slave
device A and sent to the master device.
The master device performs predetermined processing on the audio signal received from the S
line, and outputs the processed signal to two connected AP lines. The audio signal output to the
AP line connected to the slave device A is relayed to the AP line downstream by the slave device
A, and is sent to the amplifier device A. On the other hand, the audio signal output to the AP line
connected to slave device D is sequentially relayed to the AP line on the downstream side of each
device by slave device D, slave device E, and amplifier device B, and amplifier device B and
amplifier are amplified. It is sent to the device C. The amplifier device A, the amplifier device B,
and the amplifier device C amplify the audio signal received from the AP line on the upstream
side, and output the amplified audio signal to a speaker connected to itself. Here, in the
configuration shown in FIG. 1 b, two systems (a master device and a slave device A, an amplifier
device A, a slave device B and a slave device of FIG. In each of the system C, the master device,
the slave device D, the slave device E, the system of the amplifier B and the system of the
amplifier C), the audio signal is transmitted by the transmission path in each system as shown in
FIGS. It is also possible to make a transmission. Hereinafter, 1-port master, 2-port master, 1-port
sub-master, 2-port sub-master, 1-port slave, 2-port slave, 1-port amplifier, which enables the
configuration and signal transmission of such an audio system The details of the 2-port amplifier
will be described. First, FIG. 3 a 1 shows the internal configuration of the 1-port master. As
shown, the 1-port master has one signal port 311 capable of detachably connecting the AP line
and the S line, a control port 301 capable of detachably connecting the CNT line, the controller
302, and a signal. A processing unit 303, a switching unit 321, and a driver unit 322 are
included. The control unit 302 performs control via the CNT line of each amplifier device and
each slave device and control of the signal processing unit 303. The signal processing unit 303
performs predetermined audio processing on the audio signal input from the S line via the signal
port 311, the switching unit 321, and the driver unit 322, and transmits the audio signal via the
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driver unit 322, the switching unit 321, and the signal port 311. , Output to the AP line. As
shown in FIG. 3 a 2, the driver unit 322 amplifies an input audio signal from the S line input via
the signal port 311 and the switching unit 321 and sets it as an audio signal input S in of the
signal processing unit 303. And an output driver 341 for amplifying and outputting the audio
signal output APout of the signal processing unit 303.
The switching unit 321 has a drain connected to the S line terminal of the signal port 311 and a
drain connected to the AP line terminal of the signal port 311 and a drain connected to the input
of the input driver. It has a MOS FET 352 whose source is connected to the output. An ON signal
(a constant voltage larger than the voltage value of the output driver 341 and the input driver
331) than the voltage value of the output of the output driver 341 or the audio signal input /
output from the signal port 311 is always applied to the gates of the MOS FETs 351 and 352.
The MOS FETs 351 and 352 are always on. Next, FIG. 3 b 1 shows the internal configuration of
the two-port master. As illustrated, the two-port master includes a control port 381, a control
unit 382, and a signal processing unit 383. Further, two sets 371 and 372 of a set of the signal
port 311, the switching unit 321 and the driver unit 322 in the one-port master shown in FIG.
3a1 are provided. The control unit 382 performs control via the CNT line of each amplifier
device and each slave device and control of the signal processing unit 383. The signal processing
unit 383 performs predetermined audio processing on the audio signal input from the S line via
the signal port 311, the switching unit 321, and the driver unit 322 for each of two systems of
the set 371 and the set 372 , An operation of outputting to the AP line through the driver unit
322, the switching unit 321, and the signal port 311, or the signal port 311 of any one system of
the two systems of the set 371 and the set 372, the switching unit 321, The audio signal input
from the S line through the driver unit 322 is subjected to predetermined audio processing, and
output to the AP line through the driver unit 322 of both systems of the set 371 and the set 372,
the switching unit 321, and the signal port 311 Do the action etc. Here, as shown in FIG. 3 b 2,
the internal configurations of the switch unit 321 and the driver unit 322 of the set 371 and the
set 372 are also the internal configurations of the switching unit 321 and the driver unit 322 of
the 1 port master shown in FIG. Is the same as Next, FIG. 4a1 shows the internal configuration of
the 1-port submaster. As shown, the 1-port sub-master includes one signal port 411 capable of
detachably connecting the AP line and the S line, a control port 401 capable of detachably
connecting the CNT line, and a control unit 402. A signal processing unit 403, a switching unit
421, and a driver unit 422 are included.
When functioning as a master device, the control unit 402 controls the signal processing unit
403, the switching unit 421, and the driver unit 422 via the CNT line of each amplifier device
and each slave device, and functions as a slave device. When doing so, the signal processing unit
403, the switching unit 421, and the driver unit 422 are controlled according to the control of
the master device via the CNT line. When the signal processing unit 403 functions as a master
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device, the signal processing unit 403 performs predetermined audio processing on an audio
signal input from the S line via the signal port 411, the switching unit 421, and the driver unit
422, and then the driver unit 422 and the switching unit 421. , And output to the AP line via the
signal port 411. Further, when functioning as a slave device, the audio signal generated in the
signal processing unit 403 is output to the S line via the driver unit 422, the switching unit 421,
and the signal port 411. As shown in FIG. 4 a 2, the driver unit 422 amplifies an input audio
signal from the S line input via the signal port 411 and the switching unit 421 and sets it as an
audio signal input S in of the signal processing unit 403. 431 and an output driver 441 for
amplifying and outputting the audio signal output APout / Sout of the signal processing unit 403.
The switching unit 421 has a drain connected to the S line terminal of the signal port 411 and a
drain connected to the S line terminal of the signal port 411 and a drain connected to the input
terminal of the input driver 431. The MOS FET 452 has a source connected to the source and a
drain connected to the AP line terminal of the signal port 411 and a source connected to the
output of the output driver 441. Either the ON signal or the OFF signal which is the zero voltage
is applied to the gate of each of the MOS FETs 451 to 453 by the control unit 402, and either the
ON state or the OFF state is selected according to the applied signal. Take. FIG. 5a1 shows the
state of the switching unit 421 when functioning as a master device, and only the MOS FETs 451
and 453 are controlled by the control unit 402 to be turned on, and the input audio signal from
the S line is processed by the signal processing unit 403. The output audio signal APout of the
signal processing unit 403 is output to the AP line. On the other hand, FIG. 5a2 shows the state
of the switching unit 421 when functioning as a slave device, and only the MOS FET 452 is
controlled by the control unit 402 to be turned on, and the output audio signal Sout of the signal
processing unit 403 is the S line. Output to
Next, FIG. 4 b 1 shows the internal configuration of the 2-port sub master. As shown, the twoport sub-master has two signal ports 511 and 512 capable of detachably connecting the AP line
and the S line, and a control port 501 and controller capable of detachably connecting the CNT
line. A signal processing unit 503, a switching unit 521, and a driver unit 522 are included. The
control unit 502 controls the signal processing unit 503, the switching unit 521, and the driver
unit 522 via the CNT line of each amplifier device or each slave device when functioning as a
master device, and functions as a slave device when functioning as a slave device. Control of
operations of the signal processing unit 503, the switching unit 521, and the driver unit 522 is
performed according to the control of the master device via a line. As shown in FIG. 4 b 2, the
driver unit 522 amplifies the audio signal and inputs it to the audio signal input Sin of the signal
processing unit 503, and the signal processing unit 503 amplifies the audio signal. A second
input driver 532 for inputting to the audio signal input APin of the first, an audio signal output
Sout of the signal processing unit 503, an output of the first input driver 531 and an audio signal
output APout of the signal processing unit 503 561, a second selector 562 which receives the
audio signal output APout of the signal processing unit 503 and the output of the second input
driver 532, a first output driver 541 which amplifies the output of the first selector 561, and a
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second selector And a second output driver 542 for amplifying the output of the The switching
unit 521 has a drain connected to the S line terminal of the signal port A 511 and a drain
connected to the S line terminal of the signal port B 512, whose drain is connected to the input of
the first input driver 531. A MOS FET 552 connected with a source connected to the input of the
first input driver 531. A MOS FET 553 connected with a drain connected to the S line terminal of
the signal port A 511 and a source connected to the output of the first output driver 541. The
drain is connected to the AP line terminal of the MOS FET 554 whose drain is connected to the
input of the second input driver 532 and the AP line terminal of the signal port A 511 and the
source is connected to the output of the first output driver 541 MOS FET 555, signal port The
drain is connected to the terminal for S line of the gate B 512 and the drain is connected to the
terminal for AP line of the signal port B 512, whose drain is connected to the output of the first
output driver 541 and to the input of the second input driver 532. The source is connected to the
MOS FET 557, the drain is connected to the AP line terminal of the signal port A 511, the MOS
FET 558 is connected to the output of the second output driver 542, and the drain is connected
to the AP line terminal of the signal port B 512 And a MOS FET 559 whose source is connected
to the output of the second output driver 542.
Either the ON signal or the OFF signal which is the zero voltage is applied to the gate of each of
the MOS FETs 551 to 559 by the control unit 502, and either the ON state or the OFF state is
selected according to the applied signal. Take. The first selector 561 and the second selector 562
select and output one of the plurality of inputs according to the control of the control unit 502.
The operation of such a two-port submaster is as follows. First, when functioning as a master
device, the following operation is performed. That is, when the slave device serving as the source
of the audio signal is connected to the signal port A 511 side, as shown in FIG. 5 b 1, the control
unit 502 turns on only the MOS FETs 551, 555, and 559 and the first selector 561 is a signal
The audio signal output APout of the processing unit 503 is selected, and the second selector
562 is controlled to select the APout of the signal processing unit 503. Then, the audio signal
input from the S line of the signal port A 511 through the switching unit 521 and the driver unit
522 is used as the audio signal input Sin of the signal processing unit 503, and the signal
processing unit 503 performs predetermined audio processing. The audio signal output APout
subjected to audio processing by the signal processing unit 503 is output to the AP line of the
signal port A 511 and the signal port B 512 via the driver unit 522 and the switching unit 521.
Further, when the slave device serving as the source of the audio signal is connected to the signal
port B 512 side, as shown in FIG. 5 b 2, in the control unit 502, only the MOS FETs 552, 555,
and 559 turn on and the first selector 561 is The audio signal output APout of the signal
processing unit 503 is selected, and the second selector 562 is controlled to select the APout of
the signal processing unit 503. Then, the audio signal input from the S line of the signal port B
512 via the switching unit 521 and the driver unit 522 is used as the audio signal input Sin of
the signal processing unit 503, and the signal processing unit 503 performs predetermined
audio processing. The audio signal output APout subjected to audio processing by the signal
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processing unit 503 is output to the AP line of the signal port A 511 and the signal port B 512
via the driver unit 522 and the switching unit 521. The operation when functioning as a slave
device is as follows. That is, when the slave device serving as the source of the audio signal is not
itself and the upstream is on the signal port A 511 side, as shown in FIG. 5 b 3, the control unit
502 turns on only the MOS FETs 522, 523, 524, and 529. Thus, the first selector 561 selects the
output of the first input driver 531, and the second selector 562 controls to select the output of
the second input driver 532.
Then, the audio signal input from the S line of the signal port B 512 is relayed to the S line of the
signal port A 511 via the switching unit 521 and driver unit 522 and output, and the audio signal
input from the AP line of the signal port A 511 Are relayed to the AP line of the signal port B 512
via the switching unit 521 and the driver unit 522 and output. When the slave device serving as
the source of the audio signal is not itself but the upstream is on the signal port B 512 side, as
shown in FIG. 5 b 4, the control unit 502 turns on only the MOS FETs 551, 556, 557, 558. Thus,
the first selector 561 selects the output of the first input driver 531, and the second selector 562
controls to select the output of the second input driver 532. Then, the audio signal input from
the S line of the signal port A 511 is relayed to the S line of the signal port B 512 via the
switching unit 521 and driver unit 522 and output, and the audio signal input from the AP line of
the signal port B 512 Are relayed to the AP line of the signal port A 511 via the switching unit
521 and the driver unit 522 and output. When the slave device serving as the source of the
audio signal is itself and the upstream is on the signal port A 511 side, as shown in FIG. 5 b 5, the
control unit 502 controls only the MOS FETs 553, 554, and 559. The first selector 561 selects
the audio signal output Sout of the signal processing unit 503, and the second selector 562
controls to select the output of the second input driver 532. Then, the audio signal output Sout
generated by the signal processing unit 503 is output to the S line of the signal port A 511
through the driver unit 522 and the switching unit 521, and the audio is input from the AP line
of the signal port A 511. The signal is relayed to the AP line of the signal port B 512 via the
switching unit 521 and the driver unit 522 and is output. On the other hand, when the slave
device serving as the source of the audio signal is itself and the upstream is on the signal port B
512 side, as shown in FIG. 5 b 5, the control unit 502 turns on only the MOS FETs 556, 557 and
558. The first selector 561 selects the audio signal output Sout of the signal processing unit 503,
and the second selector 562 controls to select the output of the second input driver 532. Then,
the audio signal output Sout generated by the signal processing unit 503 is output to the S line of
the signal port B 512 via the driver unit 522 and the switching unit 521, and the audio is input
from the AP line of the signal port B 512. The signal is relayed to the AP line of the signal port A
511 via the switching unit 521 and the driver unit 522 and is output.
Next, FIG. 6a1 shows the configuration of a one-port slave. As illustrated, the 1-port slave has one
signal port 611 capable of detachably connecting the AP line and the S line, a control port 601
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capable of detachably connecting the CNT line, the controller 602, and a signal. A processing unit
603, a switching unit 621, and a driver unit 622 are included. The control unit 602 controls the
signal processing unit 603 according to the control from the master device via the CNT line. The
signal processing unit 603 outputs the audio signal generated in the signal processing unit 603
to the S line via the driver unit 622, the switching unit 621, and the signal port 611. As shown in
FIG. 6 a 2, the driver unit 622 has an output driver 641 that amplifies and outputs the audio
signal output Sout of the signal processing unit 603. The switching unit 621 includes a MOS FET
651 whose drain is connected to the S line terminal of the signal port 611 and whose source is
connected to the output of the output driver. The above-mentioned ON signal is constantly
applied to the gate of the MOS FET 651 by the control unit 602 to be in the ON state. However,
the control unit 602 may turn on the MOS FET 651 only when its own device is the source of the
audio signal, and may turn off the MOS FET 651 other than that. Next, FIG. 6 b 1 shows the
internal configuration of the 2-port slave. As shown, the 2-port slave has two signal ports 711,
712 capable of detachably connecting the AP line and the S line, a control port 701 capable of
detachably connecting the CNT line, and a control unit 702. , A signal processing unit 703, a
switching unit 721, and a driver unit 722. The control unit 702 controls the operation of the
signal processing unit 703, the switching unit 721, and the driver unit 722 according to the
control of the master device via the CNT line. As shown in FIG. 6 b 2, the driver unit 722
amplifies the audio signal and inputs it to the audio signal input Sin of the signal processing unit
703, the audio signal output Sout of the signal processing unit 703, and the input driver It has a
selector 761 which receives the output of 731 and an output driver 741 which amplifies and
outputs the output of the selector 761. The switching unit 721 has a drain connected to the S
line terminal of the signal port A 711 and a drain connected to the S line terminal of the signal
port B 712, whose drain is connected to the input of the input driver 731. The MOS FET 752
whose source is connected to the input of the input driver 731, the MOS FET 753 whose drain is
connected to the S line terminal of the signal port A711 and whose source is connected to the
output of the output driver 741, the S line terminal of the signal port B712 It has a MOS FET 754
whose drain is connected and whose source is connected to the output of the output driver 741.
The AP line terminal of the signal port A 711 is directly connected to the AP line terminal of the
signal port B 712. Either the on signal or the off signal which is the zero voltage is applied by the
control unit 702 to the gate of each of the MOS FETs 751 to 754, and either of the on state or
the off state is taken according to the applied signal. Further, the selector 761 selects and
outputs one of two inputs according to the control of the control unit 702. Now, the operation of
such a two-port slave is as follows. That is, when the slave device serving as the source of the
audio signal is not itself but the upstream is on the signal port A 711 side, as shown in FIG. 7 a 1,
the control unit 702 turns on only the MOS FETs 752 and 753. Control to select the output of
the input driver 731. Then, the audio signal input from the S line of the signal port B 712 is
relayed to the S line of the signal port A 711 via the switching unit 721 and the driver unit 722
and output. Also, an audio signal input from the AP line of the signal port A 711 is directly
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relayed to the AP line of the signal port B 712 and output. When the slave device serving as the
source of the audio signal is not itself but the upstream is on the signal port B 712 side, as shown
in FIG. 7 a 2, the control unit 702 turns on only the MOS FETs 751 and 754 to select the selector
761. Control to select the output of the input driver 731. Then, the audio signal input from the S
line of the signal port A 711 is relayed to the S line of the signal port B 712 via the switching unit
721 and the driver unit 722 and output. Also, an audio signal input from the AP line of the signal
port B 712 is directly relayed to the AP line of the signal port A 711 and output. Next, when the
slave device as the source of the audio signal is itself and the upstream is on the signal port A
711 side, as shown in FIG. 7 a 3, the control unit 702 turns on only the MOS FET 753, The
selector 761 controls to select the audio signal output Sout of the signal processing unit 703.
Then, the audio signal output Sout generated by the signal processing unit 703 is output to the S
line of the signal port A 711 through the driver unit 722 and the switching unit 721. Also, an
audio signal input from the AP line of the signal port A 711 is directly relayed to the AP line of
the signal port B 712 and output.
On the other hand, when the slave device serving as the source of the audio signal is itself and
the upstream is on the signal port B 712 side, as shown in FIG. 7a4, the control unit 702 turns on
only the MOS FET 754 and the selector 761 outputs a signal. Control is performed to select the
audio signal output Sout of the processing unit 703. Then, the audio signal output Sout generated
by the signal processing unit 703 is output to the S line of the signal port B 712 via the driver
unit 722 and the switching unit 721. Also, an audio signal input from the AP line of the signal
port B 712 is directly relayed to the AP line of the signal port A 711 and output. Next, FIG. 8a1
shows an internal configuration of the one-port amplifier. As shown, the 1-port amplifier includes
one signal port 811 capable of detachably connecting the AP line and the S line, a control port
801 capable of detachably connecting the CNT line, the controller 802, and a signal. A
processing unit 803, a switching unit 821, a driver unit 822, and an audio output unit 880
connected to a speaker are included. The control unit 802 controls the operation of the signal
processing unit 803, the switching unit 821, and the driver unit 822 according to the control of
the master device via the CNT line. The signal processing unit 803 amplifies an audio signal
input from the AP line via the signal port 811, the switching unit 821, and the driver unit 822,
and outputs the amplified audio signal from the audio output unit 880 to the speaker. As shown
in FIG. 8 a 2, the driver unit 822 has an input driver 831 for amplifying an audio signal and
inputting it to the audio signal input APin of the signal processing unit 803, and the switching
unit 821 is an AP of the signal port 811. It has a MOS FET 851 whose drain is connected to the
line terminal and whose source is connected to the input of the input driver 831. The abovedescribed ON signal is constantly applied to the gate 851 of the MOS FET by the control unit 802
to be in the ON state. Next, FIG. 8b1 shows an internal configuration of the two-port amplifier. As
illustrated, the two-port amplifier includes two signal ports 911 and 912 capable of detachably
connecting the AP line and the S line, a control port 901 capable of detachably connecting the
CNT line, and a control unit 902 , A signal processing unit 903, a switching unit 921, a driver
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unit 9223, and an audio output unit 980 connected to a speaker. The control unit 902 controls
the operation of the signal processing unit 903, the switching unit 921, and the driver unit 922
according to the control of the master device via the CNT line.
As shown in FIG. 8 b 2, the driver unit 922 amplifies an audio signal and inputs it to the audio
signal input APin of the signal processing unit 903, and an output driver which amplifies and
outputs the output of the input driver 931. And 941. The switching unit 921 has a drain
connected to the AP line terminal of the signal port A 911 and a drain connected to the AP line
terminal of the signal port B 912 and a drain connected to the input of the input driver 931. The
source is connected to the input of the MOS FET 952. The drain is connected to the terminal for
AP line of the signal port A 911. The drain is connected to the terminal for AP line of the MOS
FET 953 whose source is connected to the output of the output driver 941. And a source
connected to the output of the output driver 941. The S line terminal of the signal port A 911
and the S line terminal of the signal port B 912 are directly connected. Either the on signal or the
off signal which is the zero voltage is applied by the control unit 902 to the gates of the MOS
FETs 951 to 954, and either the on state or the off state is taken according to the applied signal.
The operation of such a two-port amplifier is as follows. That is, when the upstream side is the
signal port A 911 side, as shown in FIG. 9 a 1, the control unit 902 controls so that only the MOS
FETs 951 and 954 are turned on. Then, the audio signal input from the AP line of the signal port
A 911 is relayed to the audio signal input APin of the signal processing unit 903 via the
switching unit 921 and the driver unit 922 and relayed to the AP line of the signal port B 912
Do. The audio signal input from the S line of the signal port B 912 is directly relayed to the S line
of the signal port A 911 and output. When the upstream side is the signal port B 912 side, as
shown in FIG. 9 a 2, the control unit 902 controls so that only the MOS FETs 952 and 953 are
turned on. Then, the audio signal input from the AP line of the signal port B 912 is relayed to the
audio signal input APin of the signal processing unit 903 via the switching unit 921 and the
driver unit 922, and relayed to the AP line of the signal port A911. Output. The audio signal
input from the S line of the signal port A 911 is directly relayed to the S line of the signal port B
912 and output.
When a non-signal processing apparatus which is an apparatus which does not process an audio
signal is incorporated in the middle of a daisy chain in the above audio system, as shown in FIG.
The two S-line terminals of the two signal ports 1011 and 1012 and the AP-line terminals may
be directly connected. In this apparatus, for example, the control unit 1002 causes the function
unit 1003 to execute a process requested by the master device via the control port 1001.
Further, in the above audio system, a hub device 1100 may be provided for incorporating a
plurality of slave devices as shown in FIG. 11a into a daisy chain. As shown, the hub device 1100
includes at least one upstream signal port 1101 for detachably connecting at least an S line, a
plurality of downstream signal ports 1102 for detachably connecting at least an S line, and a
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switching unit 1103. , And a switching control unit 1104. As shown in FIG. 11 b, the switching
unit 1103 has a plurality of output drivers 1122, an input driver 1124, and a plurality of drains
each connected to the S line terminal of each downstream signal port 1102 and a source
connected to the input of the input driver 1124. And a source connected to the output of the
output driver 1122 and a drain connected to the terminal for the S line of the upstream signal
port 1101. Either the ON signal or the OFF signal which is a zero voltage is applied to the gate of
each of the MOS FETs 1121 and 1123 by the switching control unit 1104, and either the ON
state or the OFF state is taken according to the applied signal. In such a configuration, when a
slave device connected downstream of the downstream signal port 1102 is used as a source of
an audio signal, the slave device is connected directly or via another slave device. Only the MOS
FET 1123 whose drain is connected to the S line signal terminal of the downstream signal port
1102 and the MOS FET 1121 whose drain is connected to the S line signal terminal of the
upstream signal port are turned on. Then, the audio signal from the slave device serving as the
source of the audio signal is relayed to the upstream S line. Although not shown, each device has
a control port, and the switching control unit 1104 of the hub device controls the operation of
the switching unit 1103 according to the control of the master device via the CNT line.
Further, the above audio system may be provided with a hub device 1200 for incorporating a
plurality of slave devices or amplifier devices as shown in FIG. 12A into a daisy chain. As shown,
the hub device 1200 includes one upstream signal port 1201 for detachably connecting the AP
line and the S line, and a plurality of downstream signals for detachably connecting the AP line
and the S line. A port 1202, a switching unit 1203, and a switching control unit 1204 are
included. As shown in FIG. 12b, in addition to the configurations 1121 to 1124 shown in FIG.
11b, the switching unit 1203 has a plurality of MOS FETs 1214 each of which has a drain
connected to the AP line terminal of each downstream signal port 1202; The MOSFET 1211
whose drain is connected to the AP line terminal of the signal port 1201, the input driver 1212
whose input is connected to the source of the MOS FET 1211 connected to the AP line terminal
of the upstream signal port 1201, and the input driver 1212 The output has a plurality of output
drivers 1213 whose inputs are connected to the outputs, and the output of each output driver
1213 is connected to the source of the MOS FET 1214 connected to the AP line terminal of the
downstream signal port 1202. Either the on signal or the off signal which is the zero voltage is
applied to the gate of each of the MOS FETs 1121, 1123, 1211, and 1214 by the switching
control unit 1204, and the on state and the off in accordance with the applied signal. Take one of
the states. In such a configuration, when a slave device connected downstream of the
downstream signal port 1202 is used as a source of an audio signal, the slave device is connected
directly or via another slave device. Only the MOS FET 1123 whose drain is connected to the S
line signal terminal of the signal port 1202 and the MOS FET 1121 whose drain is connected to
the S line signal terminal of the upstream signal port 1201 are turned on. Then, the audio signal
from the slave device serving as the source of the audio signal is relayed to the upstream S line.
Also, the MOS FETs 1211 and 1214 are always turned on, and the audio signal input from the
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signal line terminal for the AP signal of the upstream signal port 1201 is distributed by the input
driver 1212 and the output driver 1213 and the AP line for each downstream signal port 1202 It
is relayed to the terminal for output.
Although not shown, each device has a control port, and the switching control unit 1204 of the
hub device controls the operation of the switching unit 1203 according to the control of the
master device via the CNT line. Now, for the clock and frame synchronization required for
transmission of audio signals in the above audio system, for example, a line for synchronization
signal is separately connected to each device and the synchronization signal is supplied from
each master device to each device. Alternatively, the audio signal can be framed and transmitted,
and a synchronization signal can be included in the preamble part of the frame. Also, in the
above audio system, a slave device or amplifier device having two signal ports needs to know
which signal port is on the upstream side, and it is necessary to use one-port submaster or twoport sub The master needs to know whether it should act as a master or as a slave. These pieces
of information may be set individually for each device, but can also be set automatically for the
master device and each slave device, for example, by the following method. That is, at the time of
initial operation immediately after power on, the master device transmits an inquiry signal to the
AP line of each signal port. At the time of initial operation, the control unit of the slave device or
amplifier device having two signal ports monitors the reception of the inquiry signal from the AP
line of both signal ports, and receives the inquiry signal if it receives the inquiry signal.
Recognizes that the signal port is upstream, and transmits the received inquiry signal from the
downstream signal port to the AP line. In addition, devices that are 1-port submasters or 2-port
submasters perform the above operations as slave devices at the time of initial operation, but
after the start of the initial operation, within a predetermined period operated to be different for
each submaster. When the inquiry signal is not received, the above operation is performed as a
master device. Note that the 2-port sub-master functioning as a 2-port slave or slave device is not
a slave device that itself is the source only when the downstream slave device is actually the
source. The following operations may be performed. As described above, according to the present
embodiment, the audio system including a plurality of slave devices and amplifier devices is only
connected by daisy chaining the slave devices and the amplifier devices sequentially without
having to consider the connection order. Can be easily built.
Further, the change of the configuration of the audio system can be easily performed as well. In
addition, since the S line, which is a transmission line used to transmit a signal toward the master
device, and the AP line, which is a transmission line used to transmit a signal downstream from
the master device, are separately provided, signal transmission of each device Can be simplified
as compared with the case of bi-directional transmission of signals on the same signal line.
Moreover, by adopting daisy chain connection, wiring can be reduced as compared with the case
of performing star type wiring. In particular, if the connection of CNT lines is also daisy chained,
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CNT lines, S lines, and AP lines between two devices can be realized in the form of one composite
cable. Of course, even when the connection of the CNT line is not a daisy chain connection, it is
preferable to realize the S line and the AP line between the two devices in the form of one
composite cable. Further, according to the present embodiment, since the transmission of the
audio signal between devices is always performed in the form of transmission from one output
driver to one input driver, even when many devices are included in the audio system The
transmission capability does not deteriorate as in the case of transmitting the audio signal
between the devices by the bus connection. Further, since a MOS FET is used as an interface
element of the audio signal transmission path and the gate voltage thereof is controlled to a
predetermined level or less, the input driver and the output driver can be protected from
overvoltage on the transmission path. In addition, since this MOS FET is also used to switch the
signal transmission path, the device configuration can be simplified. In the above description,
although the connection order on the daisy chain of the slave device and the amplifier device is
the same for the S line and the AP line, this may not be necessarily the same for the S line and
the AP line. However, in this case, in the 2-port slave device and the 2-port amplifier device, the
upstream and downstream of each of the S line and the AP line are managed, and the signal
transmission paths in the driver unit and the switching unit are switched. Furthermore, although
the application to an audio system for transmitting digital audio signals between devices has
been described above as an example, the present embodiment is similarly applied to, for example,
a video system for transmitting digital video signals between devices. It is possible. In this case,
the amplifier device in the above embodiment may be replaced by an output device such as a
display device.
Also, in this case, the master device may be, for example, a device that combines characters,
other video, and the like with the video generated by the slave device as digital video data. As
described above, according to the present invention, it is possible to provide a wire-saving signal
transmission system that can easily connect devices even when the number of devices is large. be
able to. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an exemplary
configuration of an audio system according to an embodiment of the present invention. FIG. 2 is
a diagram showing an example of a signal transmission path in an audio system according to an
embodiment of the present invention. FIG. 3 is a block diagram showing a configuration of a 1port master and a 2-port master according to an embodiment of the present invention. FIG. 4 is a
block diagram showing the configuration of a 1-port submaster and a 2-port submaster
according to an embodiment of the present invention. FIG. 5 is a block diagram showing a signal
transmission path of a 1-port submaster and a 2-port submaster according to an embodiment of
the present invention. FIG. 6 is a block diagram showing a configuration of a 1-port slave and a
2-port slave according to an embodiment of the present invention. FIG. 7 is a block diagram
showing a signal transmission path of a 2-port slave according to an embodiment of the present
invention. FIG. 8 is a block diagram showing configurations of a 1-port amplifier and a 2-port
amplifier according to an embodiment of the present invention. FIG. 9 is a block diagram
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showing a signal transmission path of the two-port amplifier according to the embodiment of the
present invention. FIG. 10 is a block diagram showing the configuration of a non-signal
processing apparatus according to an embodiment of the present invention. FIG. 11 is a block
diagram showing a configuration of a hub device according to an embodiment of the present
invention. FIG. 12 is a block diagram showing another configuration of the hub device according
to the embodiment of the present invention. [Description of the code] 301; control port, 302,
control unit, 303, signal processing unit, 311, signal port, 321, switching unit, 322, driver unit,
331, input driver, 341, output driver, 351-352; MOS FET, 381; control port, 382; control unit,
383; signal processing unit, 401; control port, 402; control unit, 403; signal processing unit, 411;
signal port, 421, switching unit, 422, driver unit, 431; input driver, 441; output driver, 451 to
453; MOS FET, 501; control port, 502: control unit, 503; signal processing unit, 511, 512; signal
port, 521; switching unit, 522; driver unit, 531; first input driver, 532; second input driver, 541;
first output driver, 542; second output dry 1st selector, 562; second selector, 601; control port,
602; control unit, 603; signal processing unit, 611; signal port, 621; switching unit, 622; driver
Part, 641; output driver, 651; MOS FET, 701; control port, 702; control part, 703; signal
processing part, 711, 712; signal port, 721; switching part, 722; driver part, 731; 741; output
driver, 761; selector, 751 to 754; MOS FET, 801; control port, 802; control unit, 803; signal
processing unit, 811; signal port, 821; switching unit, 822; driver unit, 831; Driver, 851; MOS
FET, 880; audio output, 901; control port, 902; Signal processing unit 911, 912; signal port 921;
switching unit 922; driver unit 931; input driver 941 output driver 951 to 954 MOS FET 980
audio output unit 1001; Control port, 1002, control section, 1003; functional section, 1011 and
1012; signal port, 1100; hub device, 1101; upstream signal port, 1102; downstream signal port,
1103; switching section, 1104; switching control section, 1121, 1123; MOS FET, 1122; output
driver, 1214; input driver, 1200; hub device, 1201; upstream signal port, 1202; downstream
signal port, 1203; switching unit, 1204; switching control unit, 1211, 1214 ; MOS FET, 1212;
input driver, 1213 Output driver
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