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JP2001028798

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DESCRIPTION JP2001028798
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
short circuit detection apparatus for automatically detecting a short circuit on a speaker circuit,
for example, in a commercial broadcast apparatus or an emergency broadcast apparatus, and
more particularly to the short circuit. The present invention relates to an apparatus for detecting
a short circuit of a speaker line having a function of electrically disconnecting the speaker line
from the broadcasting apparatus.
[0002]
2. Description of the Related Art Conventionally, as a broadcasting apparatus having a function of
electrically disconnecting a shorted speaker line when the speaker line is shorted as described
above, for example, there is a device as shown in FIG. . As shown in the figure, the broadcasting
apparatus includes a plurality of (six) M (speaker) speaker lines 2 to which one or more speakers
1 are connected. Each of the speaker lines 2, 2,... Is also referred to as, for example, a normal (N)
line (or a hot (H) line). 2a) and a common (COM) line 2b, which are connected in parallel to the
output side of a common amplifier 3 for amplifying and outputting a broadcast signal. Although
only one speaker 1 is described for one speaker line 2 in the same drawing for the sake of
convenience, in general, a plurality of speakers 1 are often provided for one speaker line 2.
[0003]
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1
In addition, one of the lines 2a, 2b constituting each of the speaker lines 2, 2,..., For example,
each of the normal lines 2a, 2a,. , 4, ... are provided. These relay switch circuits 4, 4, ... are
provided in the vicinity of the output side of the amplifier 3 in the respective normal lines 2a, 2a,
..., and individually supplied from the CPU (central processing unit) 5 The respective normal lines
2a, 2a,... And the output side of the amplifier 3 are individually connected or disconnected by ON
/ OFF operation according to the open / close control signal.
[0004]
The CPU 5 generates the open / close control signal according to the operated state of the
operation unit 6 having a plurality of push button keys respectively corresponding to the relay
switch circuits 4, 4,. Do. At the same time, the CPU 5 turns on or off each of the relay switch
circuits 4, 4,..., Ie, whether each of the speaker lines 2, 2,. The light emitting diode (LED) or the
liquid crystal display (LCD) is displayed on the display unit 7 of the configuration. The operation
of the CPU 5 is controlled in accordance with a program stored in the storage unit 8 having a
semiconductor memory configuration such as, for example, a ROM or a RAM.
[0005]
Furthermore, a circuit near the output side of the amplifier 3 in each of the normal lines 2a, 2a,...,
For example, between the output side of the amplifier 3 and each relay switch circuit 4, 4,.
Protective fuses 9, 9,... Are provided. As these fuses 9, 9,..., Those of standards (blowing
characteristics) according to the rated current of the speaker line 2 provided with each are used.
[0006]
The amplifier 3, the relay switch circuits 4, 4,..., The CPU 5, the storage unit 8 and the fuses 9, 9,.
Ru. And the operation part 6 and the display part 7 are arrange ¦ positioned, for example on the
operation panel which is not shown which comprises the front part of the said housing ¦ casing.
Each of the speaker lines 2, 2,... Is wired, for example, through a ceiling and a wall in a building
using this broadcast apparatus, and each speaker 1, 1,. It is properly installed in each broadcast
target area such as the corridors and rooms inside.
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[0007]
According to the configuration of FIG. 5, when each of the speaker lines 2, 2,... Is normal, each of
the speaker lines according to the ON / OFF state of each of the relay switch circuits 4, 4,.
Broadcast by 2, 2, ... can be realized. Then, when a short circuit accident occurs in any of the
speaker lines 2 and a signal for broadcast is input from the amplifier 3 to the shorted speaker
line 2 in this state, an overcurrent (short current) is generated in the shorted speaker line 2 ) And
the fuse 9 provided in the short-circuited speaker line 2 blows off (flys). As a result, the shorted
speaker line 2 and the amplifier 3 are electrically disconnected, and the respective circuits
including the shorted speaker line 2 and the amplifier 3 are protected from the above-mentioned
overcurrent. It should be noted that even if part of the speaker lines 2 is disconnected from the
amplifier 3 as described above, the other normal speaker lines 2, 2,... Therefore, the broadcast
can be continued by these normal speaker lines 2, 2,.
[0008]
Further, as another conventional example different from the above-mentioned FIG. 5, there is one
as shown in FIG. 6, for example. As shown in the figure, this is provided with current sensors 10,
10,... For each of the speaker lines 2, 2,. It is The current sensors 10 individually detect the
current flowing through the speaker lines 2, 2,..., And the detection results are input to the CPU
5. The CPU 5 calculates each current value based on each detection result obtained from each
current sensor 10, 10,... (Ie, from the magnitude of each current value detected and obtained by
each current sensor 10, 10,. It is determined whether a short circuit accident has occurred in
each of the speaker lines 2, 2,. Then, if it is determined that one of the speaker lines 2 is short
circuited (that is, if the current value obtained by detection by any one of the current sensors 10
is extremely large), the CPU 5 operates the operated unit 6. Regardless of the state, the relay
switch circuit 4 of the speaker line 2 determined to be short-circuited is turned off. As a result,
the short-circuited (strictly determined to be a short-circuited) speaker line 2 and the amplifier 3
are electrically disconnected.
[0009]
However, in the prior art shown in FIG. 5, whenever the speaker lines 2, 2,... Are shorted, the
shorted speaker lines 2, 2,. It is necessary to replace the fuses 9, 9,... This problem becomes more
pronounced as the number of shorted speaker lines 2, 2,... Increases. Also, there is a problem that
a spare fuse must be prepared in preparation for the short circuit accident.
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[0010]
On the other hand, according to the prior art shown in FIG. 6, it is not necessary to replace the
fuses 9, 9... Or to prepare spare fuses. However, since it is necessary to provide current sensors
10, 10,... For each of the speaker lines 2, 2,..., The configuration of each speaker line 2, 2,. There
is a problem of costing. This problem also becomes more pronounced as the number of speaker
lines 2, 2,.
[0011]
Therefore, according to the present invention, without providing the fuses 9, 9,..., The current
sensors 10, 10, etc. for each of the speaker lines 2, 2,. An object of the present invention is to
provide a short circuit detection device capable of detecting a short circuit accident of 2,.
[0012]
SUMMARY OF THE INVENTION In order to achieve the above object, the present invention
outputs a signal for broadcasting and a speaker circuit to which one or more speakers are
connected, and inputs it to the speaker circuit. And an output portion of the broadcast signal
output means for detecting a total output current of the broadcast signal output means, and
when the current obtained by the detection exceeds a predetermined reference value, an
overcurrent detection signal Current detection means for outputting the
[0013]
The above-mentioned broadcast signal output means referred to here is, for example, a broadcast
apparatus provided with the short circuit detection device of the present invention such as the
above-mentioned amplifier 3 etc. Say the means to
Further, the predetermined reference value is, for example, a reference for determining whether
or not an overcurrent exceeding the rated current flows in the speaker circuit from the current
value obtained by detection by the current detection means. It means the so-called threshold
value.
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As the predetermined reference value, for example, a value of about three to five times the rated
output current of the broadcast signal output means is set.
[0014]
According to the present invention, a broadcast signal is outputted from the broadcast signal
output means, and when this is inputted to the speaker circuit, a current flows from the
broadcast signal output means to the speaker circuit. Here, when the speaker line is normal, the
total output current of the broadcast signal output means, in other words, the current value
obtained by detection by the current detection means becomes equal to or less than the rated
output current of the broadcast signal output means. Therefore, in this state, the current
detection means does not output the overcurrent detection signal. On the other hand, when the
speaker line is short-circuited, an over current far exceeding the rated output current flows from
the broadcast signal output means to the speaker line. Then, the current value obtained by the
detection by the current detection means exceeds the predetermined reference value, and the
overcurrent detection signal is outputted from the current detection means. That is, it can be
recognized whether or not the speaker circuit is short-circuited based on whether or not the
overcurrent detection signal is output from the current detection means.
[0015]
Here, it is assumed that a plurality of speaker lines are connected in parallel to the broadcast
signal output means. Then, in this state, for example, it is assumed that one of the speaker lines is
shorted. Also in this case, an overcurrent flows from the broadcast signal output means to the
shorted speaker line, and an overcurrent detection signal is output from the current detection
means. As described above, even when a plurality of speaker lines are provided, when one or
more speaker lines are shorted, an overcurrent detection signal is output from the current
detection unit common to the speaker lines. Therefore, since this overcurrent detection signal is
output, it can be recognized that any one or more speaker lines are shorted.
[0016]
Further, in the present invention, a switching means is provided between the output side of the
broadcast signal output means and the input side of the speaker line, for electrically connecting
or disconnecting between the two according to the switching control signal, When the current
detection means outputs the overcurrent detection signal, the open / close control signal is
generated and supplied to the opening / closing means in a state of receiving it and
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disconnecting between the broadcast signal output means and the speaker line. Control means
may be provided.
[0017]
Thus, by providing the opening / closing means and the control means for controlling this
according to the above-mentioned overcurrent detection signal, when the speaker line is shorted,
the shorted speaker line is automatically transmitted from the broadcast signal output means.
Can be separated.
In this way, each circuit including the speaker line and the broadcast signal output means can be
protected from the above-mentioned overcurrent.
[0018]
The opening / closing means referred to herein can be constituted by, for example, a relay circuit
or the like. In particular, a broadcasting apparatus provided with the short circuit detection
device of the present invention is originally a means such as the relay switch circuit 4 described
above between the output side of the broadcast signal output means and the input side of the
speaker line, When provided with means for switching the valid and invalid states of the speaker
line according to the operated state, this can be diverted as the opening and closing means. In
this way, it is not necessary to provide a dedicated opening / closing means to realize the present
invention. Further, in this case, if means originally provided for controlling the relay switch
circuit 4 as in the CPU 5 described above is used as control means in the present invention, the
operation of the means is specifically controlled. If the program for rewriting is rewritten, it is not
necessary to provide a dedicated control means.
[0019]
Further, when a plurality of speaker lines are connected in parallel to the broadcast signal output
means, opening and closing means are provided for each of the speaker lines. The control means
is configured to, for example, disconnect between the broadcast signal output means and all the
speaker lines by the respective opening / closing means when the current detection means
outputs the overcurrent detection signal (strictly speaking, Thus, the switching control signal for
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controlling the switching means is generated).
[0020]
According to this structure, all the speaker lines can be automatically disconnected from the
broadcast signal output means when any of the speaker lines is short-circuited, and all the
speaker lines and the broadcast signal output means are included. Each circuit can be reliably
protected from the overcurrent caused by the short circuit.
[0021]
Further, in the case where a plurality of speaker lines are provided as described above and the
switching means is provided for each of the switch lines, for example, when the current detection
means outputs an overcurrent detection signal, each of the control means The speaker circuits
are sequentially connected or disconnected in a predetermined order with respect to the
broadcast signal output means in a state in which a part of each speaker line is connected to the
broadcast signal output means and the rest is disconnected by the opening / closing means. It
may be configured as follows.
At that time, if it is confirmed whether or not the current detection means outputs the abovementioned overcurrent detection signal, which speaker line is connected to the broadcast signal
output means when the current detection means outputs the above-mentioned overcurrent
detection signal That is, it can be specified which speaker line is shorted. Then, by providing
information output means for outputting information representing a speaker line identified as
being short-circuited by the control means, it is possible to easily recognize which speaker line is
short-circuited from the information.
[0022]
The information output means does not output information representing the speaker line
identified as short-circuited by the control means, but outputs information representing the other
speaker lines, that is, normal speaker lines. It may be configured as follows. Further, information
may be output that represents both of the normal speaker line and the speaker line identified as
having a short circuit. And the information said here may be output in a visual form by using
display means, such as a light emitting diode and a liquid crystal panel, for example, and may be
output in the auditory form, such as an audio ¦ voice and a warning.
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[0023]
Here, as described above, for example, the following two procedures may be mentioned as
specific procedures for sequentially connecting or disconnecting the speaker lines to the
broadcast signal output means in the predetermined order by the control means. Be That is, as
the first procedure, when the current detection means outputs an overcurrent detection signal
(ie, when any of the speaker lines is shorted), the broadcast signal output means is once
disconnected from all the speaker lines. Do. Then, in this state, the speaker lines are sequentially
connected to the broadcast signal output means in units of a predetermined number of lines, for
example, one by one. Thus, all the speaker lines are connected to the above-mentioned broadcast
signal output means one by one independently, and in this state, if it is confirmed whether the
above-mentioned current detection means outputs an over-current detection signal, all the
speakers It is possible to reliably check whether the circuits are shorted or not.
[0024]
On the other hand, in the second procedure, reversely to the first procedure, when the current
detection means outputs the overcurrent detection signal, the connection between the broadcast
signal output means and all the speaker lines is once made. In this state, the broadcast signal
output means sequentially disconnects the speaker lines, for example, one by one, in units of a
predetermined number of lines. That is, by connecting all the speaker lines to the broadcast
signal output means, the current detection means intentionally outputs the overcurrent detection
signal. Then, the speaker lines are separated one by one from the broadcast signal output means,
and in the process, the time point when the overcurrent detection signal is not output from the
current detection means is confirmed. In this way, it is possible to identify that the speaker line in
the state of being separated from the broadcast signal output means is short circuited when the
overcurrent detection signal is not output from the current detection means.
[0025]
The second procedure can often detect a short-circuited speaker line earlier than the first
procedure. However, according to the first procedure, it is possible to reliably check whether or
not each of the speaker lines is shorted, whereas according to the second procedure, a plurality
of speaker lines are simultaneously shorted. Sometimes this is very difficult to detect.
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[0026]
Therefore, when the current detection means outputs an overcurrent detection signal, first, each
speaker line is inspected in accordance with the second procedure. When the shorted speaker
line can be detected by the second procedure, the information output means outputs information
representing that effect. Then, if it is not possible to identify a shorted speaker line by the second
procedure, that is, if a plurality of speaker lines are simultaneously shorted, all the speaker lines
are shorted according to the first procedure. Check if it is In this way, a shorted speaker line can
be detected early and reliably.
[0027]
Further, as to the control means, after identifying the shorted speaker line as described above,
the shorted speaker line (in other words, it is specified that the current detection means is the
cause for outputting the overcurrent detection signal) The speaker line may be disabled, and only
the other normal speaker lines may be enabled. Here, to invalidate the speaker line means, for
example, an operation corresponding to the shorted speaker line (more specifically, an operation
corresponding to the opening / closing means provided between the shorted speaker line and the
broadcast signal output means). We say to invalidate operation by means.
[0028]
According to this structure, even if one of the speaker lines is shorted and the shorted speaker
line becomes unusable, the broadcast can be continued by the other normal speaker lines.
[0029]
BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a short circuit detecting
apparatus for a speaker circuit according to the present invention will be described with
reference to FIGS. 1 to 3. FIG.
[0030]
FIG. 1A shows a schematic configuration of a broadcast apparatus provided with the short circuit
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detection apparatus of the present embodiment.
As shown in the figure, in the present embodiment, in terms of hardware, the fuses 9, 9,... Or the
current sensors 10, 10,. The amplifier 3 is configured to supply an overcurrent detection signal
to be described later to the CPU 5 from the amplifier 3.
However, the software-like operation of the CPU 5 when the overcurrent detection signal is
supplied from the amplifier 3 to the CPU 5 is different from the case of each of the abovedescribed conventional techniques, as described later. The other parts of the configuration are
the same as those of the above-described conventional techniques, and therefore, the same
reference numerals are given to these equivalent parts, and the detailed description thereof is
omitted.
[0031]
By the way, the output stage of the amplifier 3 in the present embodiment is configured as
shown in FIG. 1 (b), for example. As shown in the figure, the output stage includes, for example,
an NPN transistor 31, a DC power supply circuit 32 for driving the transistor 31, an anode
terminal of the DC power supply circuit 32, and a collector terminal of the transistor 31. An
output transformer (primary side) 33 connected in series between them, and a resistor connected
in series between the anode terminal of the DC power supply circuit 32 and the emitter terminal
of the transistor 31, so-called It is of the generally known low frequency power amplifier circuit
configuration. According to this configuration, the broadcast signal is input to the base terminal
of the transistor 31, amplified here, and then input to each of the speaker lines 2, 2,... Through
the output transformer 33.
[0032]
Then, the amplifier 3 in the present embodiment indirectly detects the potential difference
between both ends of the emitter resistor 34 to generate the above-mentioned overcurrent
detection signal. Current detection circuit 35 for detecting the current. The current detection
circuit 35 compares the detected current value IE with a predetermined reference value I0, and
detects the overcurrent when the current value IE is larger than the reference value I0 (IE> I0). A
signal is generated and supplied to the CPU 5. The reference value I0 referred to here is based on
the current value IE detected and obtained by the current detection circuit 35 to determine
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whether or not the output current of the amplifier 3 is in an overcurrent state far exceeding its
rated value. Say the threshold to do. As this reference value, for example, a value substantially
equal to the current value IE when the output current of the amplifier 3 becomes about three to
five times the rated value is set.
[0033]
That is, according to the present embodiment, when any one of the speaker lines 2, 2,... In which
the relay switch circuit 4 is turned on is shorted, the shorted speaker line 2 can be The amplifier
3 generates an overcurrent which far exceeds the rated output current. Then, the current
detection circuit 35 in the amplifier 3 generates the overcurrent detection signal and supplies it
to the CPU 5. Therefore, the CPU 5 can recognize that any one of the speaker lines 2 is shorted
by the supply of the overcurrent detection signal from the amplifier 3 (current detection circuit
35).
[0034]
However, the CPU 5 can not identify which of the speaker lines 2 is broken only by the supply of
the above-mentioned overcurrent detection signal. Therefore, as soon as the CPU 5 receives the
above-mentioned overcurrent detection signal, the CPU 5 enters the routine of FIG. 2 in order to
identify which speaker line 2 is shorted. A program for operating the CPU 5 according to the
routine of FIG. 2 is stored in the storage unit 8.
[0035]
As shown in the figure, when the CPU 5 receives the above-mentioned overcurrent detection
signal (YES in step S2), first, each relay switch circuit 4, 4,. The ON / OFF state, that is, the valid /
invalid state of each of the speaker lines 2, 2,... Is stored (step S4). Then, all the relay switch
circuits 4, 4,... Are temporarily turned off to disconnect all the speaker lines 2, 2,... From the
amplifier 3 (step S6).
[0036]
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Next, as an initial setting of this routine, the CPU 5 sets an index [m] representing the number of
each speaker line 2, 2,... To "m = 1" (step S8). After this initial setting, the CPU 5 turns on only the
relay switch circuit 4 of line number [m] to set the speaker line 2 of this line number [m]
(hereinafter referred to as a code representing the speaker line 2) Use the number [m] together. )
Is connected to the amplifier 3 (step S10), and in this state, it is checked whether the overcurrent
detection signal is supplied from the amplifier 3 (step S12). Here, when it is confirmed that the
overcurrent detection means is supplied (in the case of YES), the CPU 5 determines that the
speaker line [m] currently connected to the amplifier 3 is short-circuited. Then, after the speaker
line [m] is stored in the storage unit 8 as the short circuit line [X] (step S14), the speaker line [m]
is disconnected from the amplifier 3 (step S16). On the other hand, when the overcurrent
detection signal can not be confirmed in the step S12 (in the case of NO), the CPU 5 determines
that at least the speaker line [m] currently connected to the amplifier 3 is not shorted. The
process passes step S14 and proceeds to step S16.
[0037]
After disconnecting the speaker line [m] from the amplifier 3 in step S16, the CPU 5 performs
step S10 in the order of the line numbers [m] for all the remaining speaker lines 2, 2,. Step 16 is
repeated (steps S18 and S20).
[0038]
After executing the processing from step S10 to step S16 for all the speaker lines 2, 2,..., The CPU
5 executes the information representing the short circuit line [X] stored in step S14. It displays
on the display part 7 (step S22).
At the same time, the CPU 5 fixes the relay switch circuit 4 of the short circuit line [X] in the OFF
state, and thereafter disables the ON / OFF control of the relay switch circuit 4 of the short
circuit line [X] by the operation unit 6 (Step S24). Then, for the other normal speaker lines 2, 2,...
Excluding the short circuit line [X], the respective valid / invalid states are restored based on the
stored contents in the above step S4 (step S26), Exit this routine.
[0039]
As described above, according to the routine of FIG. 2, it is possible to individually check whether
or not each of the speaker lines 2, 2,... Then, for the short circuit [X], the information indicating
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that is displayed on the display unit 7, so that it is possible to easily recognize the line number
[m] of the short circuit [X].
[0040]
Although the short circuit [X] is invalidated, the other normal speaker lines 2, 2,... Can be used
continuously. Therefore, even if part of the speaker lines [X] is short-circuited, broadcasting can
be continued by the other normal speaker lines 2, 2,.
[0041]
In the routine shown in FIG. 2, with all the speaker lines 2, 2,... Separated from the amplifier 3,
each of the speaker lines 2, 2,. The short circuit line [X] is specified by connecting to the
amplifier 3, but conversely, with all the speaker lines 2, 2, ... connected to the amplifier 3, each
speaker line 2, 2 The short circuit line [X] can also be specified by disconnecting the line 1 to line
3 separately from the amplifier 3 respectively. This procedure will be described with reference to
FIG.
[0042]
That is, when the above-mentioned overcurrent detection signal is supplied (YES in step S30), the
CPU 5 first turns on / off each relay switch circuit 4, 4, ... at that time, That is, the valid / invalid
state of each of the speaker lines 2, 2,... Is stored (step S32). Then, all the relay switch circuits 4,
4,... Are once turned ON, and all the speaker lines 2, 2,... Are connected to the amplifier 3 (step
S34). Further, as the initial setting, the line number [m] is set to m = 1 (step S36).
[0043]
After the above initialization, the CPU 5 turns off only the relay switch circuit 4 of line number
[m] and disconnects only the speaker line [m] from the amplifier 3 (step S38). Then, in this state,
it is checked whether the overcurrent detection signal is not supplied, that is, whether the
overcurrent is eliminated (step S40). Here, when the above-mentioned overcurrent is eliminated
(in the case of YES), the CPU 5 judges that the above-mentioned speaker line [m] currently
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connected to the amplifier 3 is short-circuited, and this is regarded as a short-circuit line [X]. ] Is
stored in the storage unit 8 (step S42). Then, the information representing the short circuit [X] is
displayed on the display unit 7 (step S44), and the relay switch circuit 4 of the short circuit [X] is
fixed in the OFF state. The on / off control of the relay switch circuit 4 of the short circuit [X] is
disabled (step S46). Then, after the CPU 5 restores the respective valid / invalid states of the
other normal speaker lines 2, 2,... Excluding the short circuit line [X] based on the storage
contents in the above step S32 ( Step S48), this routine is exited.
[0044]
On the other hand, if the overcurrent is not eliminated at step S40 (in the case of NO), the CPU 5
reconnects the speaker line [m] to the amplifier 3 (step S50). Then, for the remaining speaker
lines 2, 2,..., Steps S38 and S40 are executed in the order of the line numbers [m] until the
overcurrent is eliminated (steps S52, S54).
[0045]
As described above, according to the procedure of FIG. 3, the CPU 5 exits this routine as soon as
the short circuit [X] is identified. Therefore, the short circuit line [X] can be identified earlier
compared to the procedure of FIG. 2 in which whether or not each of the speaker lines 2, 2,...
[0046]
However, according to the procedure of FIG. 3, when a plurality of speaker lines 2, 2,... Therefore,
if the above overcurrent is not eliminated even if all the speaker lines 2, 2,... Are individually
separated from the amplifier 3 (that is, YES in step S52), the CPU 5 performs line individual
inspection processing ( Step S56) is executed, and specifically, the operation is performed
according to the procedure of FIG.
[0047]
As shown in the figure, the line individual process (step S56) is completely the same as the
process from step S6 to step S20 in FIG. 2, that is, the CPU 5 first performs all the relay switch
09-05-2019
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circuits. .. Are once turned off, and all the speaker lines 2, 2,... Are disconnected from the
amplifier 3 (step S60). Then, as an initial setting in the line individual process, the line number
[m] is set to m = 1 (step S62).
[0048]
Then, only the speaker line [m] is connected to the amplifier 3 (step S64), and in this state, it is
checked whether the overcurrent detection signal is supplied from the amplifier 3 (step S66).
Here, when it is confirmed that the overcurrent detection means is supplied (in the case of YES),
the CPU 5 stores the above speaker line [m] as the short circuit line [X] in the storage unit 8 (step
S68), and thereafter , And disconnect the speaker line [m] from the amplifier 3 (step S70). On the
other hand, when the overcurrent detection signal is not supplied in step S66 (in the case of NO),
the CPU 5 passes step S66 and proceeds to step S70. Then, the CPU 5 repeats the steps S64 to
S70 in the order of the line numbers [m] for all the remaining speaker lines 2, 2,... (Steps S72 and
S74). When the processing from step S64 to step 70 is completed for all the speaker lines 2, 2,...,
The CPU 5 proceeds to step S44 and ends the series of individual line processing.
[0049]
In this way, even when a plurality of speaker lines 2, 2,... Are short-circuited, each short circuit
line [X] can be identified with certainty. Of course, if the short circuit line [X] is only one line, the
CPU 5 does not execute the line individual process (step S56), so the short circuit line [X] is
earlier than in the case of FIG. It can be identified.
[0050]
Incidentally, except for the line individual process (step S56), while the CPU 5 is executing the
procedure of FIG. 3 (strictly, until the CPU 5 enters the routine of FIG. 3 and reaches step S46. ),
The above overcurrent continues to flow. However, the specific operation of the short circuit [X]
according to the procedure of FIG. 3 is performed instantaneously (in other words, the time for
the CPU 5 to enter the routine of FIG. 3 and exit this routine is extremely short) Since there is no
influence of the above-mentioned overcurrent on each circuit including the speaker lines 2, 2,...
[0051]
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Thus, according to the present embodiment, unlike the prior art shown in FIGS. 5 and 6
described above, fuses 9, 9,... Are provided for each of speaker lines 2, 2,. The short circuit of
each of the speaker lines 2, 2 can be detected without providing the current sensors 10, 10,.
Therefore, the configuration of each of the speaker lines 2, 2,... Can be simplified and the cost can
be reduced.
[0052]
Generally, a technique is known that uses a test signal to check a short circuit of a speaker
circuit, but in the present invention, a broadcast signal output from the amplifier 3 is used for the
above test. It is diverted as a signal of Therefore, there is no need to provide special means for
generating a signal for inspection.
[0053]
Each of the relay switch circuits 4, 4,... In the present embodiment corresponds to the opening /
closing means described in the claims. Although this switching means may be configured by
means other than the relay switch circuits 4, 4,..., If the relay switch circuits 4, 4,. There is no
need to provide a dedicated one as the opening / closing means.
[0054]
Also, the CPU 5 in the present embodiment corresponds to the control means described in the
claims. Of course, the control means can be configured not only by the CPU 5 but also by, for
example, a so-called pure hardware configuration.
[0055]
The display unit 7 corresponds to the information output means described in the claims. In
addition, this information output means can be comprised not only by the display part 7, for
example, by means which outputs the information showing the said short circuit line [X] in the
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auditory form, such as an audio ¦ voice.
[0056]
In the present embodiment, a broadcast apparatus provided with a plurality of speaker lines 2,
2,... Has been described. However, the present invention can be applied to a broadcast apparatus
having only one speaker line 2. Further, the present invention can be applied not only to the twowire speaker lines 2, 2,.
[0057]
Furthermore, although the circuit shown in FIG. 1 (b) has been exemplified as a circuit for
detecting the output current of the amplifier 3, the output current of the amplifier 3 may be
detected with a circuit configuration other than this.
[0058]
Then, the CPU 5 is operated according to the procedure shown in FIG. 2 or 3 in order to specify
the short circuit [X], but the present invention is not limited to this.
That is, the CPU 5 may be operated according to a procedure other than the above-described FIG.
2 or FIG. 3 as long as the same operation and effect as those of the present embodiment can be
obtained. For example, in the procedure of FIG. 2 or FIG. 3 above, each speaker line 2, 2,... Is
connected or disconnected to the amplifier 3 one by one, but two or more lines are connected or
disconnected at a time It is also good. Also, when the short circuit line [X] is specified, the
information representing the short circuit line [X] is displayed on the display unit 7, but
conversely, the information showing normal speaker lines 2, 2,. May be displayed, or information
representing both of them may be displayed.
[0059]
As described above, according to the present invention, even if a plurality of speaker lines are
provided, whether each speaker line is disconnected by one current detecting means common to
the speaker lines It can recognize whether or not. Therefore, unlike the above-described prior art,
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it is not necessary to provide fuses 9, 9, ..., current sensors 10, 10, etc. for each speaker line.
Therefore, there is no need to prepare a fuse replacement operation or a spare fuse, and the
configuration of each speaker line can be simplified and the cost can be reduced. This effect is
more remarkable as the number of speaker lines is larger.
[0060]
Brief description of the drawings
[0061]
1 is a diagram showing an embodiment of a short circuit detection device of the speaker line
according to the present invention, (a) is a schematic configuration diagram of a broadcast device
provided with this short circuit detection device, (b) is a part of the amplifier It is an electric
circuit diagram showing.
[0062]
2 is a flowchart showing an example of the operation of the CPU in the present embodiment.
[0063]
3 is a flowchart for operating the CPU according to a procedure different from FIG.
[0064]
4 is a flowchart showing a part of FIG. 3 in detail.
[0065]
5 is a schematic configuration diagram showing an example of the prior art.
[0066]
6 is a schematic configuration view showing a conventional example different from FIG.
[0067]
Explanation of sign
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[0068]
1 Speaker 2 Speaker Line 3 Amplifier 4 Relay Switch Circuit 5 CPU 35 Current Detection Circuit
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