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The present invention relates to an electronic siren used for a security device or an alarm device
or the like. Conventionally, as this type of electronic siren, one equipped with a diaphragm driven
by a voice coil as a sound source is known. FIG. 1 is a cross-sectional view showing an example of
such a conventional electric siren. In the figure, at the heel end of a horn 10 made of synthetic
resin or the like, a sound emitting portion 11 and a case portion 13 for housing a drive circuit
portion 12 for driving the sound emitting portion are provided. The sound-producing unit 11 has
a generally disk-shaped diaphragm 14 whose periphery is supported by a corrugated elastic
member, and an IC cylindrical bobbin 15 whose end is fixed to the periphery of the diaphragm
14. A voice coil 16 wound around the outer circumference of 15 and these bobbins 15. It
consists of a permanent magnet 17 having a magnetic pole surface that holds the voice coil 16.
In addition, an alternating current is supplied to the coil 16 to vibrate the diaphragm 1'4, and the
sound wave generated as a result is transmitted to the horn 10 so as to be efficiently discharged
to the outside. . However, in the case of J: 発 音 4 [conventional electronic siren, as described
above, the thickness of the vibration direction of the sound emitting portion 11 can not be made
too small, and hence the case γ 11513 can be miniaturized. As a result, the overall length of the
device can not be known too much. Furthermore, in such a conventional electronic siren, it is
difficult to reduce the weight because a permanent magnet is used for the sounding part, and the
structure of the original high part itself is complicated and it is difficult to reduce the cost. There
was a problem with By the way, although this type of siren usually generates sound waves of a
fixed frequency, such sound waves are extremely annoying. However, it is desirable that the
sound waves have a certain bandwidth by modulation or the like to eliminate the abovementioned unpleasantness. The present invention has been made in view of the above
circumstances, and its first object is to provide an electronic siren that can be reduced in size and
weight. Still another object of the present invention is to provide an electronic siren capable of
emitting a wide band of 74 waves with extremely high efficiency. Hereinafter, embodiments of
the electronic siren according to the present invention will be described with reference to the
drawings. In this embodiment, as shown in FIGS. 2 and 3, the electronic siren 20 generally has a
base 21. Piezoelectric light sound element 22. Inner horn 23. A light sound unit 1-26 having an
intermediate horn 24J3 and an outer bone 25, a drive circuit 27J3 for driving the sound
generation diaphragm 22 and a case 28 for housing the drive circuit 27 are provided. The drive
unit 29 is engaged.
The base portion 21 is a generally annular plate made of a synthetic resin such as plastic, and the
inner peripheral portion of the portion 2 extends vertically forward (leftward in FIG. 2) to form a
cylinder portion 30. doing. At the central portion of the rear surface of the base portion 21, a
four-part 31 having a spherical surface is formed. Further, on the rear side surface of the base
portion 21, the same root-shaped piezoelectric sound-emitting element 22 is disposed so as to
cover the recess 31. The piezoelectric il y power element 22 has a brass disc 32 having a
diameter larger than a circle formed by the outer periphery of the recess 31 and a relamic disc
33 formed on the surface of the circle 4 opposite to the recess 31. And the film-like electrode 3
=! Formed on the surface of the brass disk 32 of the ceramic disk 33 on the opposite side. lどか
らなりている。 For example, PZS-R45 manufactured by Japan Specialty Ceramics Co., Ltd. can
be applied as this piezoelectric sound generation system 22. In addition, as the piezoelectric
sounding element 22, one in which a pattern of a piezoelectric element 1 made of a flexible
polymer composite piezoelectric filler is attached to a diaphragm made of metal or the like may
be used. Then, lead wires are drawn out from both electrodes of the piezoelectric sounding
element 22 and the brass brass disk 32 and the membrane electrode 34 are connected to the
output of the drive circuit 27 described later. A step 811 is formed on the inner peripheral
surface on the distal end side of the cylindrical portion 30, and the base end of the inner bone 23
is inserted into 1 and fixed to this step. In this case, the inner peripheral surface of the ;)
portion 3 o and the inner peripheral surface of the inner horn 23 coincide with each other. In
addition, you may form integrally the inner horn 23 of the base 21 any place. In addition, on the
front side surface of the base portion 21, three convex support tii portions 35a to 35c (36a) are
equally spaced in a predetermined position-circumferential direction between the cylindrical
portion 3o and the outer peripheral edge of the base portion 21. , 36b (7) are shown). A step is
formed on the outside of each tip of these support portions 368 to 36c. Then, an intermediate
wheel 24 whose base end is closed is coaxially disposed so as to cover the inner horn 23, and the
intermediate horn 21! The tip end portion of I is fixed to each of the support portions 36a to 36G
by screws or the like in accordance with the stepped portion. In this case, a predetermined
distance is secured between the distal end of the inner horn 23 and the proximal end of the
intermediate horn 24 in order to pass sound waves. The base portion 21 is fixed to the outer
bone 25 with the outer peripheral edge thereof aligned with the inner peripheral surface of the
long end portion of the outer horn 25. 23. The above-mentioned inner horn 23. Intermediate
horn 24. Each of the outer horns 25 is an exponential horn made of a plastic or other synthetic
resin or metal, and the opening area of the sound wave passage increases exponentially from the
proximal end toward the distal end. It has become.
The surface on the rear side of the base 21 is in question! A convex portion 40 is formed along
the circumferential direction at a portion slightly inside the outer peripheral edge of 61121, and
a protective disc 41 whose peripheral portion is fixed to the tip end surface of the convex portion
40 is attached to the base 21. ing. At the back of the protective disc 41, there are 11 hairs of a
case 28 for housing the drive circuit 27. The drive circuit 27 comprises, for example, a
transmitter 5 o that outputs a repetitive signal of 2.9 KHz, an amplifier 51 for amplifying the
output of the transmitter 5 °, an output impedance of the amplifier 51 and a piezoelectric
photoacoustic element 22. It is IM DX with an output capacitor 52 for matching impedances. The
secondary winding of the output capacitor 52 is connected to both electrodes of the piezoelectric
sounding rod 22 described above. In addition, the outboard 1 to lance 52 is housed in a metal
shield case 53 in order to block the radiation of the interference radio wave, and the shield case
53 is grounded. Also, as indicated by the broken line in the transmitter 50, the modulation signal
M is turned on and the frequency of the repetitive signal is changed with a predetermined
frequency width, so that the frequency modulation of the repetitive signal is performed. Good. In
the above configuration, when an alternating current or an intermittent current is supplied from
the drive circuit 27 to the piezoelectric generator 8-7 /-, the sounding element 22 vibrates at the
frequency of the alternating current or the intermittent current to generate a sound wave. It will
occur. This sound wave is an inner horn 23. Intermediate horn 24. The sentences are efficiently
output via the outer horns 25 sequentially. By the way, the present inventors set the radius of
curvature of the corner portion 42 of the boundary portion between the recess 31 of the base 21
and the sound wave passage 60 of the inner bone 23 to 3.5 mm in the siren J3 of the above
configuration. It has been found that sound waves can be emitted with high efficiency. That is,
according to this condition, the diameter of the circle formed by the outer periphery of the recess
31 is 28 + ntn. When the radius of the spherical surface of the fourth part 31 is 22+ nm and the
piezoelectric sound element 22 is driven with frequency modulation with 2.9 Kl-IZ as the center
frequency, high efficiency output is obtained between 800 to 11 and 4 Kl-IZ. 1! ! l、:。 In the
same way, assuming that 1) the radius of curvature is 2 mm, under the same conditions as above,
the band from which high efficiency output can be obtained is between I K I-I Z and 3 K I-I Z Met.
As will be apparent from this description, the electronic siren according to the present invention
is arranged with the disc-like piezoelectric light sound element and the opening on the proximal
side facing one surface of the piezoelectric sound element. Since the horn is provided, the size
and weight can be reduced or the cost reduction can be reduced to 11 L, while the J4 on the
piezoelectric element side of the horn on the piezoelectric element side and the radius of
curvature of any boundary corner of the sound wave passage If it sets to 3.5 mm, a wide-range
sound wave can be emitted with high efficiency.
Brief description of the drawings
1 is a side sectional view of a conventional electronic siren, FIG. 2 is a side sectional view of an
electronic 4 neuron according to the present invention, FIG. 3 is a rear view of the same
embodiment, and FIG. FIG. 5 is a block diagram of a drive circuit of Lielen according to this
22 ...... piezoelectric sound element, 23.24.25 ...... horn, 31 ...... recess 60 ...... sonic passage.
Applicant: Kobishi Electric a type meeting figure 2 figure 3 figure 1 figure 1