JP2011159005A - Audible alarm device and fire alarm system including the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an audible alarm device capable of suppressing the peak of current consumption. <P>SOLUTION: The audible alarm device includes: a piezoelectric buzzer ringing circuit 30 having a piezoelectric buzzer 32, a coil 33 connected in parallel to the piezoelectric buzzer 32, a transistor 35 to adjust a current supply period for the piezoelectric buzzer 32 and the coil 33 and a control circuit 31 to control the on/off-operation of the transistor 35 by changing a frequency; and a capacitor 23 connected in parallel to the piezoelectric buzzer ringing circuit 30. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an acoustic alarm device for sounding a piezoelectric buzzer and a fire alarm facility equipped with the same.

2. Description of the Related Art Conventionally, there is known a piezoelectric buzzer driving method in which a booster coil and a piezoelectric element are connected in parallel to an output terminal of a switching transistor to generate sound (for example, see Patent Document 1).
Moreover, there is an alarm device that “changes the ringing frequency of the piezoelectric buzzer by changing the frequency of the voltage output to the piezoelectric buzzer” (see, for example, Patent Document 2).

Japanese Patent Laid-Open No. 57-210396 (page 2, FIG. 1) JP 2009-59137 A (page 2, page 5, FIG. 4)

According to the technique described in Patent Document 1, after applying a voltage to a coil and accumulating (accumulating) energy as magnetic energy in the coil, releasing the energy accumulated in the coil, Let it ring. When the energy accumulated in the coil is released, a boosted voltage due to the back electromotive voltage of the booster coil that is higher than the voltage applied to the coil is generated, so that the sound pressure of the piezoelectric buzzer can be increased.
On the other hand, the piezoelectric buzzer has a specific frequency, and when driven at a frequency deviating from this specific frequency, the sound pressure may drop suddenly. According to the technique described in Patent Document 2, the driving frequency of the piezoelectric buzzer is changed, so that even a piezoelectric buzzer with a variation in the inherent frequency can be struck with a high sound pressure at any timing. . Also, the current consumption varies depending on the drive frequency of the piezoelectric buzzer, but by changing the frequency and ringing the piezoelectric buzzer, it is possible to include the frequency at which the piezoelectric buzzer can ring with low current consumption. Can be reduced.

  However, the power consumption of the entire piezoelectric buzzer is reduced by changing the drive frequency, but the peak of the current consumption does not change. For this reason, it is necessary to use a power source having a large capacity that satisfies this peak current and to use a fuse having a larger capacity.

  The present invention has been made to solve the above-described problems, and provides an acoustic alarm device capable of suppressing a peak of current consumption and a fire alarm facility equipped with the same.

  The acoustic alarm device according to the present invention includes a piezoelectric buzzer, a coil connected in parallel to the piezoelectric buzzer, a switching unit that adjusts the energization time of the piezoelectric buzzer and the coil, and a frequency that changes the switching unit. A piezoelectric buzzer sounding circuit having control means for controlling on / off operation, and a capacitor connected in parallel to the piezoelectric buzzer sounding circuit are provided.

  The acoustic alarm device according to the present invention includes current limiting means for limiting current supplied to the piezoelectric buzzer sounding circuit and the capacitor.

In addition, the duty ratio of the on / off operation for adjusting the energization time to the coil is changed.
Further, the duty ratio of the on / off operation for adjusting the energization time to the coil is changed so that the on time is constant.

  A fire alarm facility according to the present invention includes a fire receiver and the above-described acoustic alarm device connected to the fire receiver via a signal line serving as a signal transmission / reception path, and the acoustic alarm device includes the fire receiver. Sounds based on a control signal transmitted from the machine.

  A fire alarm facility according to the present invention includes a fire receiver, and the plurality of acoustic alarm devices connected to the fire receiver via signal lines serving as signal transmission / reception paths, wherein the plurality of acoustic alarm devices are Based on the control signal transmitted from the fire receiver, the sound is intermittently sounded synchronously between the plurality of sound devices.

  The acoustic alarm device according to the present invention includes a capacitor connected in parallel to the piezoelectric buzzer ringing circuit. For this reason, when the consumption current of the piezoelectric buzzer sounding circuit is small, it can be stored in the capacitor, and when the current consumption is large, current can be supplied from the capacitor to the piezoelectric buzzer sounding circuit. Therefore, the peak of current consumption of the piezoelectric buzzer sounding circuit can be suppressed.

  Further, since the current limiting means for limiting the current supplied to the piezoelectric buzzer sounding circuit and the capacitor is provided, the peak of the current consumption of the piezoelectric buzzer sounding circuit can be further suppressed.

  According to the acoustic alarm device of the present invention, the frequency of the on / off operation for adjusting the energization time to the coil is changed, and the duty ratio of the on / off operation is changed. For this reason, it is possible to shorten the time for energizing the coil when driving at a low frequency, and to reduce the current consumption.

1 is an overall configuration diagram of a fire alarm facility including an acoustic alarm device according to Embodiment 1. FIG. 1 is a block diagram of a fire alarm facility according to Embodiment 1. FIG. FIG. 3 is a schematic diagram showing current limitation of the acoustic alarm device according to the first embodiment. It is a figure which shows an example of the sound pressure and current consumption of a piezoelectric buzzer when the frequency applied to the piezoelectric buzzer which concerns on Embodiment 1 is changed. It is a figure which shows an example of the sound pressure and current consumption of a piezoelectric buzzer when the frequency applied to the piezoelectric buzzer which concerns on Embodiment 1 is changed. It is a block diagram of the acoustic alarm device concerning Embodiment 1, and is a figure at the time of using a PNP type transistor for switching means. It is a figure which shows the switching waveform of the acoustic alarm device which concerns on Embodiment 2, and the charging waveform of a coil. FIG. 6 is a block diagram of a fire alarm facility according to Embodiment 3. It is a figure explaining the signal which a fire receiver transmits, and the transmission signal waveform which a terminal device and an acoustic alarm device receive. It is a block diagram of the fire alarm equipment which concerns on Embodiment 4.

Embodiment 1 FIG.
In the first embodiment, the acoustic alarm device according to the present invention is a so-called R-type fire that notifies the occurrence of a fire when receiving a fire signal detected by a fire detector or the like by transmitting and receiving a transmission signal (pulse signal). A case where the present invention is applied to a fire alarm facility having a receiver will be described as an example.

[Fire alarm equipment]
(overall structure)
First, the fire alarm facility according to the first embodiment will be described.
1 is an overall configuration diagram of a fire alarm facility according to Embodiment 1. FIG. FIG. 2 is a block diagram illustrating the configuration of the fire alarm facility according to the first embodiment. Various terminal devices are connected to the fire receiver FA via a signal line SG.

  In FIG. 1, a photoelectric analog sensor SE11, a thermal analog sensor SE12, an addressable transmitter SE13, an acoustic alarm device C11, and a smoke control relay D11 are connected to a signal line SG. In the first embodiment, devices connected to the fire receiver FA through the signal line SG may be collectively referred to as terminal devices.

The photoelectric analog sensor SE11 is a kind of smoke sensor, and transmits the detected smoke analog value to the fire receiver FA.
The thermal analog sensor SE12 is a kind of thermal sensor, and transmits an analog value of the detected ambient temperature to the fire receiver FA.
The addressable transmitter SE13 is a so-called fire transmitter, and includes a push button that is manually operated by a person who finds the fire, and transmits a fire signal to the fire receiver FA when the push button is turned on.

The acoustic alarm device C11 is an acoustic alarm device according to the present invention. The acoustic alarm device C11 performs acoustic ringing with a piezoelectric buzzer in order to notify a fire in accordance with a control signal from the fire receiver FA.
The acoustic alarm device C11 is connected to the fire receiver FA by a signal line SG, and is connected to the fire receiver FA by a power line PG as a power source for driving a piezoelectric buzzer.

Further, the smoke prevention control repeater D11 is connected with a fire door D111, a smoke exhauster D112, a shutter D113, and a leaning wall D114 as smoke prevention equipment.
In FIG. 1, smoke-proof devices as controlled devices as described above are connected one by one, but a plurality of devices can be connected, and other terminal devices can also be connected. is there.

  The terminal devices connected to these signal lines SG communicate with the fire receiver FA via the signal lines SG and are supplied with power via the signal lines SG.

(Operation of fire alarm equipment)
Next, an example of the operation of the fire alarm facility will be described.
First, when the photoelectric analog sensor SE11 connected as a terminal device detects smoke or the thermal analog sensor SE12 detects heat, the detected information is sent as status information to the fire receiver FA via the signal line SG. Is transmitted.
The fire receiver FA collects status information transmitted from the photoelectric analog sensor SE11 and the thermal analog sensor SE12, and the collected status information includes fire information (detection information exceeding a predetermined threshold). If it is, a control signal is transmitted to the sound alarm device C11 to sound it. In addition, when a fire occurs, the fire receiver FA transmits a control signal to the smoke prevention control relay D11 to operate the fire door D111, the smoke exhaust D112, the shutter D113, the leaning wall D114, etc. prevent.

(Communication operation)
Next, communication performed between the fire receiver FA and the terminal device will be described.
The fire receiver FA and the terminal device communicate with each other by a pulse signal of a combination of a high level voltage (V1H) and a low level voltage (V1L).

(1) About a normal communication method The fire receiver FA communicates with each terminal device in order to collect state information of each terminal device (see FIG. 1) connected to the signal line SG.

The fire receiver FA can collect state information of the terminal device and control the terminal device and the like by the following three methods with each terminal device.
(1-1) Point polling The fire receiver FA transmits a status information request command to a terminal device by collecting several units as one group in order to collect the status of a plurality of connected terminal devices. On the other hand, each terminal device measures the timing according to its own address in response to the status information request command, and reports the status information to the fire receiver FA. The fire receiver FA repeatedly communicates with such a group and collects status information of all terminal devices.

(1-2) Selecting The fire receiver FA designates an address corresponding to a desired terminal device and transmits a predetermined control command to control the terminal device or state information or the like to the desired terminal device. Status information can be collected from individual terminal devices. In response to the control command, the terminal device to which the address is designated reports the control result to the fire receiver FA or reports the requested status information.

(1-3) System polling The fire receiver FA can control each terminal device by transmitting a common control command to all the terminal devices. Here, as a control command by system polling, for example, a fire recovery command (command to restore a sensor or a relay that outputs a fire signal to a normal monitoring state), a district sound stop command (sounding sound alarm device) Command to stop C11).

(2) Collection of information on occurrence of abnormality The fire receiver FA stores the storage unit 13 when the fire information is included in the state information collected by terminal polling from the terminal device such as the photoelectric analog sensor SE11. In accordance with the database stored in, a control signal is transmitted by selecting and operated to the smoke prevention control repeater D11 corresponding to the terminal device that transmitted the fire information. In addition, when a status information request command is transmitted by point polling to a terminal device registered in the database stored in the storage unit 13 of the fire receiver FA, a terminal device that does not respond to the status information request command. If it exists, a non-response failure alarm is issued by the display operation unit 12 or the like.

[Block diagram of fire alarm equipment]
Next, a detailed configuration of the fire alarm facility will be described.
In FIG. 2, the fire receiver FA and the acoustic alarm device C11 are mainly described for the sake of explanation.

(Fire receiver)
The fire receiver FA includes a control unit 11, a display operation unit 12, a storage unit 13, and a transmission / reception unit 14. A battery 15, a power supply circuit 16, and a fuse 17 are provided.
The control unit 11 controls the entire operation including the display operation unit 12 and the transmission / reception unit 14 according to a control program or the like stored in advance in the storage unit 13.
The display operation unit 12 includes display means such as a screen and a lamp for displaying information related to the fire detected by the terminal device and the state of each terminal device, and a touch panel and buttons for performing operations on the fire receiver FA and each terminal device. Etc. are provided.
The transmission / reception unit 14 is controlled by the control unit 11 to transmit a signal to each terminal device, and receives a signal transmitted from each terminal device.
The storage unit 13 stores a program and various data for operating the control unit 11.

The battery 15 is one of the power supplies supplied to the acoustic alarm device C11 via the power line PG at the time of a power failure. The power supplied from the battery 15 is adjusted to a predetermined voltage by the power supply circuit 16 and supplied to the power supply line PG. When there is no power failure, the power supplied from a commercial power outlet (not shown) is adjusted to a predetermined voltage by the power circuit 16 and supplied to the power line PG.
The fuse 17 protects the fire receiver FA from an overcurrent when an overcurrent occurs.

(Configuration of acoustic alarm device)
The acoustic alarm device C11 is connected to the signal line SG and the power supply line PG, and includes a transmission / reception circuit 20, a current limiting circuit 22, a capacitor 23, a piezoelectric buzzer sounding circuit 30, and the like.

  The transmission / reception circuit 20 receives the control signal transmitted from the fire receiver FA via the signal line SG, performs reception processing of the control signal, and is controlled by the control circuit 31 to give a predetermined signal to the fire receiver FA. Send the signal.

  The constant voltage circuit 21 supplies the power obtained via the power line PG to the current limiting circuit 22 as a predetermined constant voltage power source.

The current limiting circuit 22 is a circuit that limits the current supplied to the load side to a predetermined value.
A capacitor 23 is connected to the downstream side of the current limiting circuit 22.

Further, a piezoelectric buzzer sounding circuit 30 is connected in parallel with the capacitor 23.
The piezoelectric buzzer sounding circuit 30 includes a control circuit 31, a piezoelectric buzzer 32 and a coil 33 connected in parallel, a transistor 35, a resistor 36, and a resistor 37. The transistor 35 and the resistor 36 constitute current limiting means 34.

  The transistor 35 is an NPN transistor, and is connected in series to the piezoelectric buzzer 32 and the coil 33 connected in parallel. The transistor 35 is controlled by the control circuit 31 via a resistor 37 for protecting the transistor 35, and performs an on / off operation so as to switch the energization time to the piezoelectric buzzer 32 and the coil 33.

  The piezoelectric buzzer 32 is a buzzer that is configured by adhering ceramics on which electrodes are formed and a metal plate, and that makes an acoustic sound due to a piezoelectric effect that is generated when a voltage is applied. The piezoelectric buzzer 32 has a natural frequency that resonates (resonance frequency), and the pitch and sound pressure level of the piezoelectric buzzer 32 vary depending on the applied voltage and the frequency of the applied voltage.

  The coil 33 is connected in parallel with the piezoelectric buzzer 32. By turning on the transistor 35, an on-current corresponding to the on-continuation time flows through the coil 33, and energy is stored. When the energy stored in the coil 33 is released by turning off the transistor 35, a boosted voltage is generated by a back electromotive voltage higher than the voltage applied to the coil 33. A high voltage can be applied to the piezoelectric buzzer 32 by this boosted voltage, and the sound pressure level of the piezoelectric buzzer 32 can be increased.

  The current limiting unit 34 includes a transistor 35 and a resistor 36 connected in series to the transistor 35. A resistor 36 is connected to the emitter side of the transistor 35 to constitute an emitter follower circuit. Since the current limiting means 34 can fix the voltage applied to the resistor 36 when the transistor 35 is on-controlled, the current flowing through the resistor 36 is limited to a predetermined current. Therefore, the current flowing through the coil 33 connected in series with the resistor 36 via the transistor 35 can be limited.

When receiving the acoustic ringing control signal from the fire receiver FA, the control circuit 31 turns on / off the transistor 35 at a predetermined frequency and applies a voltage to the coil 33 at the predetermined frequency. The boosted voltage generated in the coil 33 when the transistor 35 is turned off is applied to the piezoelectric buzzer 32 so that the piezoelectric buzzer 32 sounds.
Here, the driving frequency of the piezoelectric buzzer 32 capable of obtaining the maximum sound pressure varies among the individual. If the drive frequency is adjusted in accordance with the characteristics of each individual piezoelectric buzzer 32, each piezoelectric buzzer 32 can ring at the maximum sound pressure. Take it. Further, since the drive frequency of the piezoelectric buzzer 32 that can obtain the maximum sound pressure can be changed depending on the temperature condition of the installation location, the maximum sound pressure is not always obtained even if it is adjusted.
Therefore, the control circuit 31 sweeps the frequency at which the transistor 35 is turned on / off, that is, the frequency of the voltage applied to the piezoelectric buzzer 32 within a predetermined range. For example, a voltage is applied in increments of 0.1 kHz, such as 2.5 kHz, 2.6 kHz, 2.7 kHz,..., 3.5 kHz, and the piezoelectric buzzer 32 is caused to ring at that frequency. In this way, by sweeping the frequency of the voltage to be applied within a predetermined range, it is possible to sound the sound with the highest sound pressure level at any timing. Since the transistor 35 operates as a switch for turning on / off the current control means 34 and is also used as a component of the current limiting means 34, the number of parts can be reduced and the cost is excellent.

(Operation when sound alarm device rings)
The operation at the time of sounding of the acoustic alarm device C11 configured as above will be described.
When an on / off voltage is applied to the coil 33 by the transistor 35 controlled by the control circuit 31, the piezoelectric buzzer 32 sounds. As described above, since the control circuit 31 sweeps the frequency of the voltage to be applied within a predetermined range, the piezoelectric buzzer 32 can ring at the maximum sound pressure at any timing regardless of the variation in the inherent frequency. .

  Further, the current gradually increases as a voltage is applied to the coil 33, but the current limiting means 34 limits a current exceeding a predetermined value. Note that the current limit value by the current limiter 34 is set to a value slightly larger than the current value at which the magnetic flux is saturated in consideration of the error of the coil 33.

  FIG. 3 is a diagram schematically showing the current limited by the current limiting means 34. In FIG. 3, the solid line indicates the current flowing in the coil 33 of the acoustic alarm device C11 according to the first embodiment, the alternate long and short dash line indicates the current that flows when the current limiting means 34 is not provided, and the area indicated by the diagonal lines. This is the amount of current reduced by the first embodiment.

  As shown in FIG. 3, the current limiting means 34 can limit the current flowing through the coil 33 to a predetermined limit value. That is, it is possible to suppress a wasteful current from flowing after the magnetic flux of the coil 33 is saturated, and to reduce the maximum value of the current flowing through the coil 33.

Next, the operation of the capacitor 23 will be described.
FIG. 4 is a diagram showing waveforms of sound pressure level and current consumption of the piezoelectric buzzer 32 when the frequency applied to the piezoelectric buzzer 32 is changed. In FIG. 4, the current consumption when the capacitor 23 is provided as in the first embodiment is indicated by a solid line, and the current consumption when the capacitor 23 is not provided is indicated by a broken line.

  Here, in FIG. 4, attention is paid to the sound pressure level of the piezoelectric buzzer 32 and a conventional graph of current consumption. As shown in FIG. 4, when the piezoelectric buzzer 32 is sounded by changing the frequency, the peak of the sound pressure level of the piezoelectric buzzer 32 does not necessarily match the peak of the consumption current. That is, even if the current consumption is increased, it cannot be said that the current necessarily contributes to an increase in the sound pressure level. In this case, useless current consumption occurs.

  The acoustic alarm device C11 according to the first embodiment includes the capacitor 23 connected in parallel to the piezoelectric buzzer sounding circuit 30. For this reason, the surplus current is stored in the capacitor 23 when the current consumed by the piezoelectric buzzer sounding circuit 30 is small. When the current consumed by the piezoelectric buzzer sounding circuit 30 is large, the current stored in the capacitor 23 is released. As a result, as shown by a solid line in FIG. 4, the peak (maximum value) of the current consumption can be suppressed and the current consumption can be substantially averaged.

  FIG. 5 is a diagram showing the sound pressure level and current consumption waveform of the piezoelectric buzzer 32 when the frequency applied to the piezoelectric buzzer 32 is changed, and the effects produced by the current limiting circuit 22 are the same as those in FIG. It is added to the figure.

As described above, the current limiting circuit 22 limits the current flowing to the load side. That is, as shown in FIG. 5, the current limiting circuit 22 suppresses the current consumption in the region indicated by “x” hatching. Therefore, the peak (maximum value) of current consumption can be suppressed.
Even when the load side including the charging current of the capacitor 23 exceeds the constant current limited by the current limiting circuit 22, the current limiting circuit 22 limits the current and supplies the current from the constant voltage circuit 21. It is suppressed that it is done. As a result, an insufficient amount of current is supplied from the stored capacitor 23.
Then, as indicated by “|” hatching in FIG. 5, when the current required for sounding the sound on the load side is less than the current limited by the current limiting circuit 22, the capacitor 23 is charged. The current limiting circuit 22 is mainly provided for limiting the current when the charging current of the capacitor 23 increases.

  As described above, according to the acoustic alarm device C11 according to the first embodiment, the current flowing through the coil 33 can be limited by the current limiting circuit 34. Moreover, the capacitor 23 can suppress and average the current peak consumed by the piezoelectric buzzer sounding circuit 30. Further, the current flowing through the piezoelectric buzzer sounding circuit 30 can be limited by the current limiting circuit 22.

And in the fire alarm facility to which a plurality of acoustic alarm devices C11 are connected, a more remarkable effect can be obtained.
In the fire alarm facility shown in FIG. 1, there is a facility in which a plurality of acoustic alarm devices C11 are connected to the fire receiver FA, and the acoustic alarm device C11 intermittently sounds acoustically such as “boo, boo, boo”. If the plurality of acoustic alarm devices C11 intermittently sound at different timings, it is difficult for the user to hear them, so the timing of the sounding may be synchronized. That is, the plurality of acoustic alarm devices C11 connected to the fire alarm facility will sound at the same timing. For this reason, the current consumed at the same timing also increases, so that it is necessary to increase the power supply capacity and the capacity of the power supply circuit 16.
However, according to the acoustic alarm device C11 according to the first embodiment, it is possible to suppress the peak of current consumption during sounding. Therefore, the current consumption when a plurality of acoustic alarm devices C11 sound simultaneously can be suppressed as a whole, the capacity of the battery 15 and the power supply circuit 16 of the fire receiver FA can be reduced, and the cost can be reduced. Can do.

Also, the capacity of the fuse provided in the fire receiver FA can be optimized. That is, if the capacity of the fuse 17 is small, the fuse is frequently blown at the peak of current consumption, and it becomes difficult to stably operate the fire alarm system. On the other hand, if the capacity of the fuse 17 is increased, there is a possibility that the overcurrent cannot be detected at the timing when the overcurrent is originally desired to be detected.
However, since the current consumption of the acoustic alarm device C11 according to the first embodiment is limited by the current limiting circuit 22, the maximum current consumption per unit is almost constant. Conventionally, it is assumed that the maximum current consumption per unit is large in consideration of errors and individual differences for each acoustic alarm device C11, and when connecting a plurality of acoustic alarm devices C11, the number of such units is taken into account. Therefore, it could not be said that the optimum capacity was selected. However, according to the acoustic alarm device C11 according to the first embodiment, the maximum current consumption per unit is substantially constant, so that the capacity of the fuse can be optimized. Therefore, the fire receiver FA can be appropriately protected.

In the first embodiment, the example in which the transistor 35 is configured by an NPN transistor has been described. However, the transistor 35 may be configured by a PNP transistor.
FIG. 6 is a circuit diagram of the acoustic alarm device C11 when a PNP transistor is used as the transistor 35A.
As shown in FIG. 6, a resistor 36 is connected to the emitter side of the transistor 35A. A resistor 37 for protecting the transistor 35A is connected to the base side of the transistor 35A. The piezoelectric buzzer 32 and the coil 33 are connected in parallel to the collector side of the transistor 35A. The current limiting unit 34A includes a transistor 35A and a resistor 36.
Even in such a configuration, the current limiting means 34A limits the peak of the current flowing through the coil 33, and the same effect as when an NPN transistor is used as the switching means can be obtained.

  In the first embodiment, the switching means such as a transistor for adjusting the energization time to the coil 33 and the current limiting means such as a current limiting circuit for limiting the current to the coil 33 are combined as one component. May be provided separately. Even in this case, the peak current flowing in the coil 33 can be suppressed.

Embodiment 2. FIG.
In the first embodiment described above, an example is shown in which the frequency of the voltage applied to the piezoelectric buzzer is swept within a predetermined range. In the second embodiment, the voltage applied to the piezoelectric buzzer is further duty controlled. In the second embodiment, differences from the first embodiment will be mainly described, and the same or corresponding components as those in the first embodiment are denoted by the same reference numerals.

  FIG. 7 is a diagram showing an on / off waveform of the transistor 35 and a charging waveform of the coil 33 when the frequency of the voltage to be applied is changed. FIGS. 7 (a1), (b1), and (c1) show on / off waveforms of the switching means. The transistor 35 is turned off when the line is on the lower side, and the transistor 35 is turned on when the line is on the upper side. The charging current waveforms of the coil 33 corresponding to these are shown in FIGS. 7 (a2), (b2), and (c2), and the more current flows through the coil 33 as the line goes upward.

  When the transistor 35 is turned on as shown in FIG. 7 (a1), a charging current gradually flows through the coil 33 as shown in FIG. 7 (a2). Then, when the transistor 35 is turned off, the coil 33 is discharged.

  Here, as described above in the first embodiment, the switching means sets the frequency in increments of 0.1 kHz, for example, 2.5 kHz, 2.6 kHz, 2.7 kHz,..., 3.5 kHz. A voltage is applied to the coil 33 by changing the voltage.

  FIG. 7 (b1) shows a waveform when switching is performed at half the frequency of FIG. 7 (a1). As shown in the figure, when the switching frequency is halved, the time for continuously applying the voltage to the coil 33 is doubled, and the charging current to the coil 33 is also increased. For example, assuming that the boosting voltage sufficient to ring the piezoelectric buzzer is obtained with the charging current waveform of the coil 33 shown in FIG. 7A2, useless current consumption occurs in the coil 33 shown in FIG. 7B2. It can be said that.

Therefore, as shown in FIG. 7C1, the duty ratio of the on / off operation of the switching means is changed. Specifically, the switching means is turned off until the second on-time shown in FIG. 7 (b1), with the on-time of the switching means being the same as in FIG. 7 (a1).
By doing in this way, as shown in FIG.7 (c2), the consumption current in the coil 33 can be reduced. Although shown in FIG. 7 (c2), the current limiting effect by the current limiting means 34 can be obtained in the same manner as described in the first embodiment.

  Thus, according to the acoustic alarm device according to the second embodiment, the duty ratio of the voltage applied to the coil 32 is changed. For this reason, since it can suppress that the electric current which does not contribute to the sound pressure level rise of the piezoelectric buzzer 32 flows, power consumption can be reduced.

Embodiment 3 FIG.
In the fire alarm facility according to the first embodiment described above, the fire receiver FA and the acoustic alarm device C11 are connected by the signal line SG and the power line PG. That is, the acoustic alarm device C11 obtains a power source for sounding the piezoelectric buzzer 32 from the power line PG.
In the third embodiment, a fire alarm facility when the signal line SG also serves as a power supply line will be described as an example. In the third embodiment, differences from the first embodiment will be mainly described, and the same or corresponding components as those in the first embodiment are denoted by the same reference numerals.

FIG. 8 is a circuit configuration diagram of the fire receiver FA and the acoustic alarm device C11 of the fire alarm facility according to the third embodiment.
As shown in FIG. 8, the fire receiver FA and the acoustic alarm device C11 are connected by a signal line SG which also serves as a power line. Unlike FIG. 2 described in the first embodiment, the power supply circuit 16 of the fire receiver FA is connected to the signal line SG, and the constant voltage circuit 21 of the acoustic alarm device C11 is also connected to the signal line SG. In addition, the circuit configurations of the control circuit 31, the current limiting circuit 22, the capacitor 23, the piezoelectric buzzer 32, the coil 33, and the current limiting means 34 are the same as those in FIG.

  Even in such a configuration where the signal line SG serves as both a signal line and a power supply line, the current consumption required for the sounding of the acoustic alarm device C11 can be reduced as in the first embodiment.

In general, when the power source and the load are connected by wiring, the voltage reaching the load side is smaller than the voltage applied on the power source side due to the resistance of the wiring. In the example of FIG. 8, the voltage reaching the acoustic alarm device C11 and other terminal devices is smaller than the voltage applied to the signal line SG from the power supply circuit 16 of the fire receiver FA.
This will be specifically described with reference to FIG.
FIG. 9 is a schematic diagram of a pulse signal transmitted by the fire receiver FA and a pulse signal received by the acoustic alarm device C11 which is a terminal device.
The fire receiver FA transmits a signal to the acoustic alarm device C11 as a pulse signal that combines the high level voltage (V1H) and the low level voltage (V1L).
The signal transmitted from the fire receiver FA has a voltage of E = R × I due to the line resistance R of the signal line SG and the current consumption I of the acoustic alarm device C11 and other terminal devices connected to the signal line SG. Reduced and applied to the acoustic alarm device C11 and other terminal devices. Therefore, E increases as the current consumption I increases.
Then, the acoustic alarm device C11 and other terminal devices receive a pulse signal that combines a high level voltage (V2H) and a low level voltage (V2L).

  When E (difference between the voltage applied on the transmission side and the voltage applied on the reception side) increases, the acoustic alarm device C11 and other terminal devices cannot determine the high level voltage (V2H) as a high level signal, and communication is not possible. There is a possibility that it will not be established. Further, when the low level voltage (V2L) is lowered, the applied voltage is lowered, so that the acoustic alarm device C11 and the terminal device may not be able to operate.

Therefore, especially when the signal line SG also serves as a power supply line as in the third embodiment, it is particularly important to reduce the peak of the consumption current of the acoustic alarm device C11. That is, by reducing the peak of current consumption, E (the difference between the voltage applied on the transmission side and the voltage applied on the reception side) can be reduced, and the signal applied by the fire receiver FA can be reduced. Can be suppressed.
Further, since E can be reduced by reducing the peak of the current consumption of the acoustic alarm device C11, the distance of the signal line SG can be extended or an inexpensive thin wiring can be used (increasing the resistance of the wiring). . Moreover, it is also possible to increase the number of terminal devices to be connected instead of reducing the peak of current consumption.

Embodiment 4 FIG.
In the above-described first embodiment, the case where the acoustic alarm device according to the present invention is applied to a fire alarm facility equipped with a so-called R-type fire receiver has been described as an example. In the fourth embodiment, a case where the acoustic alarm device according to the present invention is applied to a fire alarm facility equipped with a so-called P-type fire receiver will be described as an example. In the fourth embodiment, differences from the first embodiment will be mainly described, and the same or corresponding components as those in the first embodiment are denoted by the same reference numerals.

FIG. 10 is a circuit configuration diagram of the fire receiver FA and the acoustic alarm device C11 of the fire alarm system according to the fourth embodiment.
As shown in FIG. 10, the fire receiver FA and the acoustic alarm device C11 are connected by a power line PG.

  The fire receiver FA includes a relay 18 that is controlled by the control unit 11, and is a fire detector such as a photoelectric sensor or a heat sensor that notifies other terminal devices of, for example, a fire signal using an on / off signal. When the fire signal is received from the power supply, the relay 18 is controlled to apply a voltage from the power supply circuit 16 to the power supply line PG.

Although the acoustic alarm device C11 does not include the transmission / reception circuit 20 shown in the first embodiment, the circuit of the control circuit 31, the current limiting circuit 22, the capacitor 23, the piezoelectric buzzer 32, the coil 33, and the current limiting means 34 is also provided. The configuration is the same as in FIG.
In the acoustic alarm device C11, when a voltage is applied to the power supply line PG, the control circuit 31 starts its operation and causes the piezoelectric buzzer 32 to ring.

  Even in such a configuration where the power line PG is connected to the so-called P-type fire receiver FA, the current consumption required for the sounding of the acoustic alarm device C11 is reduced as in the first embodiment. Since the capacity of the battery 15 and the power supply circuit 16 of the fire receiver FA can be reduced, the cost can be reduced. Moreover, the capacity of the fuse can be optimized, and the fire receiver FA can be appropriately protected.

  DESCRIPTION OF SYMBOLS 11 Control circuit, 12 Display operation part, 13 Memory | storage part, 14 Transmission / reception part, 15 Battery, 16 Power supply circuit, 17 Fuse, 18 Relay, 20 Transmission / reception circuit, 21 Constant voltage circuit, 22 Current limiting circuit, 23 Capacitor, 30 Piezoelectric buzzer Ringing circuit, 31 control circuit, 32 piezoelectric buzzer, 33 coil, 34 current limiting means, 34A current limiting means, 35 transistor, 35A transistor, 36 resistance, 37 resistance, SG signal line, PG power line.

Claims (6)

Piezoelectric buzzer,
A coil connected in parallel to the piezoelectric buzzer,
Switching means for adjusting energization time to the piezoelectric buzzer and the coil;
And a piezoelectric buzzer sounding circuit comprising control means for controlling the on / off operation of the switching means by changing the frequency,
An acoustic alarm device comprising: a capacitor connected in parallel to the piezoelectric buzzer ringing circuit. The acoustic alarm device according to claim 1, further comprising current limiting means for limiting a current supplied to the piezoelectric buzzer sounding circuit and the capacitor. The acoustic alarm device according to claim 1, wherein the control unit changes a duty ratio of the switching unit. The acoustic alarm device according to claim 1, wherein the control unit changes the duty ratio so that the energization time to the coil is constant. A fire receiver,
The sound alarm device according to any one of claims 1 to 4, wherein the sound alarm device is connected to the fire receiver via a signal line serving as a signal transmission / reception route,
The sound alarm device sounds sound based on a control signal transmitted from the fire receiver. A fire receiver,
A plurality of acoustic alarm devices according to any one of claims 1 to 4, which are connected to the fire receiver via a signal line serving as a signal transmission / reception route,
The plurality of sound alarm devices sound intermittently and synchronously between the plurality of sound devices based on a control signal transmitted from the fire receiver.

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