JPS5784599

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DESCRIPTION JPS5784599
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1A, a top view and a front view showing an
example of a piezoelectric buzzer, FIG. 2 is a diagram for explaining the vibration state of the
buzzer, and FIG. 3 is a conventional piezoelectric buzzer sounding body FIG. 4 is a sectional view
showing an embodiment of the piezoelectric buzzer sounding body according to the present
invention. 1 · · · Piezoelectric ceramic plate, 2 · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · elastic body,
11.12 · · · · · Enclosed space.
DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a piezoelectric
buzzer sounding body, the purpose of which is to make the sound pressure greater and the shape
thinner. The piezoelectric buzzer has a structure in which a thin piezoelectric ceramic plate is
bonded to a vibrating plate such as a thin metal plate, and is generated by the flexural vibration
generated by the expansion and contraction of the piezoelectric plate when an AC signal is
applied to the piezoelectric ceramic plate. It is efficient because it becomes a direct sound
transducer because the diaphragm is a direct sound generator, and it is often used as a buzzer
that does not consume Km as it is thin. ing. This π 3 L · 6 ー 7 electric buzzer: In general, the
outer periphery of a diaphragm such as a metal plate is fixed and an external signal is: (therefore,
there is much use of other excitation which generates sound. However, in the case of such usage,
the input impedance of the piezoelectric buzzer is large and it is difficult for a large input to be
input, so it is unsuitable for a method of generating a large sound pressure. Generally, a node
portion at the time of free vibration of a piezoelectric buzzer is fixed and used for generating a
large sound pressure or for self-excitation. This will be described based on the figure. 9 shows a
piezoelectric buzzer. In the figure, 1 is a piezoelectric ceramic plate, 2 is a diaphragm such as 7
dedicated metal plate, etc. and is bonded and integrated with the piezoelectric ceramic plate 1
described above. Part 2A shows three force thin sections as a dynamic characteristic at basic
resonance when an alternating current sign is added to the piezoelectric ceramic plate 1. In this
case, node portions 3 for a use type buzzer (- 1 Discoid also becomes circular method. FIG. 3
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shows an example of a conventional 1+ city buzzer one sounding body in which the abovementioned node portion is fixed and casing, and the node portion of the diaphragm 2 of the
piezoelectric buzzer is made in a piece aa, 4b 1 The annular projection 6 is firmly fixed to the
annular projection 6 by an elastic body 7 such as silicone rubber. When the sound output hole 5
is opened in lTl 11 where the piezoelectric ceramic plate 1 of the diaphragm 2 is not attached to
the case 4a, the sound comes out through the sound output hole 5. Further, the electrical
connection with the electrodes of the piezoelectric ceramic plate 1 is led to the terminal 9 by
soldering of lead wires or the like, and at this time, one of the electrodes of the piezoelectric
ceramic plate 1 is taken out via the diaphragm 2. Furthermore, in order to increase the sound
pressure, K is often performed by acoustic resonance between the sound output hole 5 and the
space 8 surrounded by the protrusion 6 and the diaphragm 2. Here, as is apparent from FIG. 2,
the sound coming from the front and back of the diaphragm 2, that is, the surface of the
piezoelectric ceramic plate 1 to which the piezoelectric ceramic plate 1 is attached and the other
surface do not have a phase of 18 o 0. Therefore, depending on the shape 9 frequency of the
piezoelectric buzzer, the sound is attenuated by the wraparound.
For this reason, in FIG. 3, the projection 6 prevents the wraparound of the surface fl] (lf
electromagnetic pattern plate 11111), so that the space 8 of the sound emission hole VI] and the
opposite side are separated. ,, "). However, in this case, the sound emitted from the sound
emission hole 5 is due to the photographing movement of the diaphragm 2 in the space 8-/ to 0,
and the vibration of the other part of the four pixels is not utilized for the M effect as a sound.
Also, when the sound release hole is opposite to that in FIG. 3, that is, the terminal 9 side, the
effective vibration area of the diaphragm 2 increases, but the sound pressure due to the
wraparound from the back surface (side where the piezoelectric ceramic plate 1 is not attached).
Deterioration occurs. In order to reduce it even a little, take the distance of the end of the buzzer
as the distance between the sound emission hole and the bottom of the case against the
diaphragm on the opposite surface, and use the bottom of the case as a reflector. The phase of
the coming sound is shifted by 1800 and the sound pressure is maintained. As described above,
the conventional structure has problems such as the reduction of the effective vibration area and
the increase of the shape due to the reflection plate. The present invention has been made to
eliminate such problems, and one practical sleeve example thereof will be described with
reference to FIG. As shown in FIG. 4, according to the present invention, a thin film 1o of vinyl
chloride or the like is provided to prevent vibration of the gap between the work portion of the
diaphragm 2 and the case 4d. It is a closed space 11. In FIG. 4, the sound output hole 5 may be
provided in the terminal 9Ill. Therefore, in the present invention, one of the forces on the front
and back of the diaphragm 2 is used as the sealed space 11 (or 12). As described above, the
piezoelectric buzzer sound producing body of the present invention is configured, and according
to the present invention, the effective area which can be taken out as a sound is also entirely, and
no sound wraps around from the back side. It can be used without attenuation and is a useful
dog.
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