JP4676470B2 - Private broadcasting system - Google Patents

Description

  The present invention relates to a local broadcasting system, and more particularly to expansion and backup.

  In general, in-building broadcasting systems are provided as disaster prevention systems in buildings, stations, airport facilities, and the like. This on-site broadcasting system is used to warn people on the premises and to guide evacuation in the event of an emergency such as a fire or gas leak. In addition, the local broadcasting system is also used for calling people, business communication, BGM broadcasting, and the like. An example of a local broadcasting system is disclosed in Patent Document 1.

  According to the technique in Patent Document 1, the local broadcasting system itself includes a mixer amplifier and a power amplifier, and outputs are supplied from the power amplifier to a plurality of speakers.

JP 2002-344406 A

  Buildings such as buildings, stations, and airports where on-site broadcasting systems are installed may be renovated. In this case, a new floor may be amplified, and it is necessary to add speakers to the floor. However, when the number of speakers is increased, it is necessary to replace the power amplifier with one having a larger output, or to newly install a power amplifier for an additional speaker separately from the existing power amplifier. In any case, the cost burden is large.

  In addition, when the power amplifier fails or a power failure occurs, it is necessary to wait for the power amplifier to be replaced or to recover from the power failure, and there is a problem that the broadcast cannot be quickly restored.

  The present invention provides a local broadcasting system that can easily add a speaker while using a power amplifier and a speaker line of an existing local broadcasting system and can continue broadcasting even if a power amplifier malfunctions or a power failure occurs. The purpose is to provide a system.

In the private broadcasting system according to an aspect of the present invention, the power amplification means amplifies the audio signal from the audio signal source and outputs the audio signal. A plurality of first group speakers are connected to the output terminal of the power amplifying means in parallel with each other via a first transmission line. The power amplifying means and the first group of speakers are connected with high impedance. As the power amplifying means, either an analog power amplifying means or a digital power amplifying means can be used. Because of the high impedance connection, the output voltage of the power amplifying means is higher than the output voltage of the normal power amplifying means, for example, the effective value is 100 V or 70 V, and the output impedance is the output of the normal power amplifying means. It is set higher than the impedance. Each speaker in the first group has a matching transformer, and the combined value of the input side impedances of these matching transformers is set to substantially match the output impedance of the power amplifying means. A power amplifying means having a voltage gain of zero dB is connected to the first transmission line. A plurality of second group speakers are connected in parallel to each other through the second transmission line to the zero-dB power amplifying means. An output voltage equal to the output voltage of the power amplification means is supplied to the plurality of second group speakers via the zero dB power amplification means . The zero dB power amplification means and the second group of speakers are also connected in high impedance. Zero dB power amplifying means can be analog power amplifying means or digital power amplifying means.

  In the private broadcasting system configured as described above, the audio signal is power amplified by the power amplifying means, supplied to the first group of speakers via the first transmission line, and then amplified. The output voltage from the power amplifying means is supplied to the power amplifying means having a voltage gain of 0 dB via the first transmission line, is only amplified without being amplified, and is supplied to each speaker of the second group. Is done. When the same power amplifying means as the power amplifying means supplying power to the first group of speakers is used instead of the zero dB power amplifying means, the voltage is amplified together with the power amplification, so that the output voltage becomes abnormally large. . In order to avoid this, it is necessary to directly supply the audio signal to the power amplifier instead of the zero dB power amplifier, and it is expensive to lay the signal line therefor. On the other hand, when the zero dB power amplifying means is used, the output voltage of the power amplifier can be supplied to the zero dB power amplifying means as it is from the end of the first transmission line, thereby simplifying the transmission line of the audio signal to be installed. This makes it easier to install.

The sum of the rated input powers of the first group of speakers is substantially equal to the rated output power of the power amplification means. In such a configuration, for example, buildings such as buildings, stations, and airports are added, and as a result, it is necessary to add the second group of speakers to a location different from the installation location of the first group of speakers. Even when the second group of speakers cannot be driven by the power amplifying means when viewed from the rated output power of the power amplifying means, the first dB power amplifying means is installed to provide the first The same audio signal as the audio signal being amplified from the group of speakers can be easily amplified from the second group of speakers.

  Alternatively, when the power amplifying means is inoperable, the output side of the zero dB power amplifying means can be connected to the first transmission line, and the audio signal can be input to the input side of the zero dB power amplifying means. In this case, it is desirable that the rated output power of the zero dB power amplifying means substantially corresponds to the total rated input of the first and second groups of speakers. With this configuration, when the power amplifying means is operating normally, the audio signal is amplified from the speakers of the first and second groups in the same manner as the one aspect described above. For example, when the power amplifying unit becomes unable to output due to a failure of the power amplifying unit or a power failure, the audio signal is supplied to the zero dB power amplifying unit, so that the audio signal is power-amplified, and the first group and the second group Supplied to the speaker. Therefore, it is possible to continue the sound amplification of the audio signal, and it is possible to reliably perform emergency broadcasting. Note that the first and second transmission lines can be installed in different places, or can be installed in the same place. When installed in the same location, the zero-dB power amplification means and the second group of speakers function as a backup for the power amplification means and the first group of speakers, and can prevent the loudspeaker from cease and can be installed in different locations. In this case, it is possible to easily cope with the case of extension of the building, and the zero dB power amplification means and the second group speaker function as a backup of the power amplification means and the first group of speakers, It is possible to prevent the loud sound from ending.

  As described above, according to the present invention, it is possible to easily increase the number of speakers using the power amplifying means and transmission line of the existing premises broadcasting system, or to continue broadcasting even if the power amplifying means fails or a power failure occurs. It becomes possible to do.

  As shown in FIG. 1, the local broadcasting system of one embodiment of the present invention has an audio signal source, for example, a local broadcasting sound source 2. For example, a microphone or a BGM sound source is used as the sound source 2.

  The audio signal from the sound source 2 is supplied to power amplification means, for example, a power amplifier 4. As the power amplifier 4, various known ones such as a class AB amplifier, a class B amplifier, and a class D amplifier are used. However, in the power amplifier 4, the output impedance is set to a normal output impedance, for example, in the order of kΩ higher than 8Ω, for example, and the output voltage is set to 100V or 70V higher than normal.

  On the output side of the power amplifier 4, a first group of speakers 6, 6... Are connected in parallel with each other via a first transmission line, for example, speaker lines 8. Although not shown, each of the first group speakers 6 and 6 has a matching transformer, its output side is connected to the voice coil of the first group speaker 6, and its input side impedance is set high. ing. The combined impedance of the matching transformer of each first group of speakers 6 is selected so as to substantially match the output impedance of the power amplifier 4. The rated output power of the power amplifier 4 is set somewhat larger than the combined value of the rated input powers of the speakers of the first group.

  The sound source 2, the power amplifier 4, and the first group of speakers 6 are installed in a building 10 as shown in FIG. 2, and the first group of speakers 6 are respectively arranged at predetermined locations on each floor. Assume that there is a newly built building 12 next to the building 10. It is necessary to install a local broadcasting system in the building 12 and broadcast the same content as in the building 10. However, since the rated output power of the power amplifier 4 is close to the combined value of the rated input powers of the first group of speakers 6, power is supplied from the power amplifier 4 to the speakers of the new local broadcasting system in the building 12. I can't afford it. However, a high output voltage of the power amplifier 4 is supplied to the ends of the speaker lines 8 and 8.

  Therefore, as shown in FIG. 1, the input side of the insulating transformer 14 is connected to the ends of the speaker lines 8 and 8, and a voltage is generated on the output side thereof. The transformation ratio of the insulating transformer 14 is set to 1: 1, and the voltage on the output side of the transformer 14 is the same as the voltage of the speaker lines 8 and 8. This voltage is supplied to a power amplifying means having a voltage gain of 0 dB, for example, a 0 dB power amplifier 16. A plurality of second speakers 18, 18... Are connected to the output side of the 0 dB power amplifier 16 in parallel with each other via second transmission lines, for example, speaker lines 20, 20. These second speakers 18, 18... Are respectively installed at predetermined locations on each floor of the building 12. Since the 0 dB power amplifier 16 amplifies only power without performing voltage amplification, its output voltage is the same as the output voltage of the power amplifier 4. Further, the second speakers 18, 18... Are provided with a matching transformer in the same manner as the first speaker 6. The rated output power of the 0 dB power amplifier 16 is set to be larger than the combined value of the rated input powers of the second group of speakers 18 and 18.

  The operating power for the 0 dB power amplifier 16 is supplied by a power supply circuit 22 that converts an AC power supply in the building 12.

  In the on-site broadcasting system configured in this way, each of the second speakers 18, 18... In the newly built building 12 is also connected to each of the first speakers 6, 6. It is possible to amplify a broadcast with the same content as that being amplified by. In addition, since the same voltage as that supplied to the first speakers 6, 6... Is supplied to each of the second speakers 18, 18. There is no need to adjust the volume at the 18 side.

  For example, when a normal power amplifier similar to the power amplifier 4 is newly installed in the building 12 and the output voltage of the power amplifier 4 is supplied to the building 12 via the insulation transformer 14, not only the output power but also the output voltage is amplified. Is done. As a result, if the gain adjustment is not performed on the power amplifier 4 side, each of the second speakers 18, 18... Is loudened with the same volume as that supplied to the first speakers 6, 6. It cannot be done, and it is difficult to adjust to the same volume.

  It is also possible to install a normal power amplifier similar to the power amplifier 4 in the building 12 and supply an audio signal from the sound source 2 to the building 12. However, a transmission line for transmitting the audio signal is separately provided. It is necessary to do this, and the laying work becomes troublesome.

  On the other hand, in this embodiment, it is possible to broadcast the same content at the same volume as the building 10 in the new building 12 without any adjustment or extra laying work.

  A second embodiment of the present invention is shown in FIG. In the first embodiment, for example, when the power amplifier 4 fails or a power failure occurs in the building 10, broadcasting stops in both buildings 10 and 12. Therefore, in the second embodiment, a normally closed switch 24 is provided between the input side of the 0 dB power amplifier 16 and the output side of the isolation transformer 14, and between the input side and the output side of each 0 dB power amplifier 16. A normally open switch 26 is provided, and a normally open switch 28 is provided between the sound source 2 and the input side of the 0 dB power amplifier 16. The normally closed switch 24 and the normally open switches 26 and 28 are controlled by a failure detection circuit 30 that detects a failure of the power amplifier 4 on the building 10 side and a power failure in the building 10.

  The failure detection circuit 30 closes the normally closed switch 24 and opens the normally open switches 26 and 28 when the power amplifier 4 on the building 10 side has not failed and no power failure has occurred in the building 10. As a result, the audio signal from the sound source 2 can be broadcast on the buildings 10 and 12 as in the first embodiment.

  The failure detection circuit 30 opens the normally closed switch 24 and closes the normally open switches 26 and 28 when the power amplifier 4 on the building 10 side fails or when a power failure occurs in the building 10. As a result, the audio signal from the sound source 2 is supplied to the 0 dB power amplifier 16 via the normally open switch 28, and the power is amplified and supplied to the second group of speakers 18, 18,. As a result, broadcasting is performed in the building 12. Further, the output of the 0 dB power amplifier 16 is supplied from the closed normally open switch 26 to the first speakers 6, 6... Via the insulating transformer 14, and broadcasting is also performed in the building 10. Therefore, emergency broadcasting can be performed at the time of a power failure or failure of the power amplifier 4. Although not shown in FIG. 3, the 0 dB power amplifier 16 is driven by the operating power generated from the AC power supply in the building 12 by the power supply circuit 22 in the same manner as in the first embodiment, and the power is not supplied to the building 10. Will work even if

  When an audio signal is transmitted from the sound source 2, it is necessary to install a transmission line. As a method for solving this problem, for example, the audio signal from the sound source 2 is digitized and the building 12 is connected via a network such as the Internet. May be demodulated by a network receiving terminal device provided on the building 12 side and supplied to the 0 dB power amplifier 16. In this case, when the voltage is amplified in the network terminal device, the power amplifier 4 operates according to the magnitude of the output voltage supplied to each of the first and second speakers 6, 6. It can be set to the same value as in the case where

  In the above-described embodiments, the case where the building 12 is newly constructed has been described. However, the present invention is not limited to this, and the present invention can also be applied to the reconstruction of an existing building. Moreover, although the transformer 14 for insulation was provided in both said embodiment, this is for ensuring safety | security more and it is unnecessary depending on the case. Further, the transformer 14 is provided at the end of the speaker lines 8, 8, but the present invention is not limited to this, and the transformer 14 may be provided in the middle of the speaker lines 8, 8.

It is a block diagram of the local broadcasting system of the 1st Embodiment of this invention. It is a perspective view which shows the building where the local broadcasting system of FIG. 1 is implemented. It is a block diagram of the local broadcasting system of the 2nd Embodiment of this invention.

Explanation of symbols

4 Power amplifier (Power amplification means)
6 First group of speakers 8 Speaker line (first transmission line)
160 dB power amplifier (zero dB power amplification means)
18 Second County Speaker 20 Speaker Line (Second Transmission Line)

Claims (2)

Power amplifying means for amplifying and outputting an audio signal from an audio signal source, and a plurality of first group speakers connected in parallel to each other via an output terminal of the power amplifying means via a first transmission line The power amplifying means and the first group of speakers are connected in high impedance, and the sum of the rated input powers of the first group of speakers is substantially equal to the rated output power of the power amplifying means .
Power amplification means connected to the first transmission line and having a voltage gain of zero dB;
A plurality of second powers connected to the zero-dB power amplifying means in parallel with each other via a second transmission line and supplied with an output voltage equal to the output voltage of the power-amplifying means via the zero-dB power amplifying means . And a second group of speakers connected to each other by a high impedance connection.   2. The private broadcasting system according to claim 1, wherein when the power amplifying means cannot output, the output side of the zero dB power amplifying means is connected to the first transmission line, and the zero dB power amplifying means is connected. A private broadcasting system that supplies the audio signal to the input side.

Images