Patent Translate
Powered by EPO and Google
This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate,
complete, reliable or fit for specific purposes. Critical decisions, such as commercially relevant or
financial decisions, should not be based on machine-translation output.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectional front view A and a
bottom view B of a three-electrode vibrator, FIG. 2 is a longitudinal sectional front view of a
piezoelectric buzzer incorporating a conventional three-electrode vibrator, FIG. Fig. 4 is a partial
front view of the present invention, Fig. 4 is a chart showing the relationship between the
temperature and resonance resistance of the conventional piezoelectric buzzer A and the buzzer
B of the present invention, and Fig. 5 similarly the relationship between temperature and
acoustic output. Is a chart showing 1, 2 · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · ·
· · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 3 · electrode type vibrator, 5 · · · · · · · · · · · · ·. ··· Case · · · · · · · · · · · ·
Support body · · · · · · · · · · · back cover, 9.10.12 · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · ······· Resonant
· Back cavity; Fig. 4 Fig. 5-
DETAILED DESCRIPTION OF THE INVENTION This invention relates to the improvement of a
piezoelectric buzzer using a piezoelectric bimorph oscillator. (10) In recent years, a piezoelectric
buzzer using a piezoelectric bimorph vibrator consisting of a piezoelectric body and a metal plate
has been widely used as a buzzer for an alarm or confirmation sound. This piezoelectric buzzer
generally uses a disk-shaped piezoelectric bimorph vibrator (hereinafter referred to as a vibrator)
in a resonance case 1 °. As this vibrator, a two-electrode type has been widely used in the past,
or recently, a three-electrode type that can be driven by a simple oscillation circuit with a small
number of parts has come to be used. This three-electrode type vibrator (4) is, as shown in FIG. 1,
a 7 ° (page 1) electrode of the gear slot, aside from the / 7-dipole (1) and (2). A feedback
electrode (3) is provided in (1), which is incorporated in a driving electric circuit such as a selfexcitation circuit to cause oscillation. The three-electrode vibrator (4) is usually coupled to a case
(6) having an opening (5) at the front through a support (7) 5, as shown in FIG. 2, and a back
cover (8) Terminals (9) (10) and electrodes (1) (2+) are connected to each other by lead wires.
Here, the case (6) mechanically protects the vibrator (4) and obtains a resonance effect based on
acoustic resonance due to the resonance cavity (I) between the vibrator and the opening (5I.
There is also a case where a driving electric circuit is accommodated on the side of the rear
surface 111 = il. However, when this vibrator is housed in a resonance case and used as a buzzer,
there is no problem in operation at room temperature, but a problem occurs when the
temperature becomes low near 0 ° C. The oscillation becomes unstable when the temperature
becomes low, that is, the oscillation occurs when the volume of the closed cavity (9) and the back
cavity (2) is reduced by reducing the external dimensions, in particular, in order to miniaturize
the buzzer. It will stop. As a result of examining this cause in detail, a buzzer. If a double ring
cavity (I) is provided on the front face of the vibrator for the purpose of increasing the acoustic
output (page 2), the resonance resistance between the terminal (9) and the terminal of the
vibrator will increase. By providing the closed cavity (6) and the back cavity (d), it has been found
that the resonance resistance is further increased, for example, the driving in the self-excitation
circuit becomes difficult 5. Furthermore, if the volume of the cavity (6) and the back cavity
(smallest) is reduced, the increase in resonance resistance becomes remarkable, so the oscillation
becomes unstable. Especially when the temperature becomes low where the excitation strength is
low, the oscillation is finally broken. It turned out to stop. IO To overcome this drawback, make
the volume of the closed cavity (6) and the back cavity (g) thicker (that is, make the outer
dimensions of the buzzer larger, but it is practical to make the outer diameter larger Not
This invention proposes to increase the external dimensions of the buzzer 15 (the I +: '# L buzzer
is proposed without such a drawback-that is, the invention has an opening (5 in the front) And, in
the case (6) in which one or more openings q に are provided on the side wall, the vibrator (4) is
coupled via the support (7), and (the third page) the back lid (8) Each of the penetrating
terminals (9) (first) and the electrodes (1) (2) is connected by a lead wire. In the figure, a terminal
02 is connected to a feedback electrode (3) by a lead wire. Although the said opening (6) showed
the thing of the slit, without being restricted to this shape, the equivalent 5 effect is acquired
with a round hole or any other shape. Next, specific embodiments of the present invention will be
described. The zircon and lead titanate based magnetism of 20 fiφ x 0.2 mt is used as a
piezoelectric material, and this is 27 ° φ x o, 2! t(Dt。 The three-electrode vibrator (4)
shown in FIG. 1 was manufactured by bonding to a brass plate. This vibrator was adhered and
fixed to a case made of a carbonated resin made of inner dimensions 28 flφ X 7 m, plate
thickness 1 fl, and front opening (5 small diameter 8 fl via a support made of foamed
polyethylene ring 7 (7). In this case, the piezoelectric buzzer A of the conventional structure
shown in FIG. 2 with the cavity (6) and the backward facing cavity (closed) closed, and the side
wall shown in FIG. The invented piezoelectric buzzer B was manufactured. Then, the temperature
change of the resonant resistance between the terminals (9) of the piezoelectric buzzers A and H
and C10 (page 4) was measured. The results are shown in FIG. From this result, it can be seen
that the resonance resistance of the conventional piezoelectric buzzer A significantly increases
when the temperature is low, and it is difficult to oscillate in the electric circuit. On the other
hand, the piezoelectric buzzer B according to the present invention maintains a low resonance
resistance value even at low temperatures, and it is expected that a stable oscillation state can be
obtained. Father The above-mentioned piezoelectric buzzers A and B were respectively
incorporated in the self-excitation circuit, a power supply voltage of 12 V was applied, and the
reverberation output at the front 30QTn of the buzzer was measured. The results are shown in
FIG. According to this result, the conventional piezoelectric buzzer A stopped its oscillation at
about 5 ° C. and did not operate at a lower temperature than that, but the piezoelectric buzzer B
according to this invention could be as low as 30 ° C. You can see that it works stably.
According to the present invention, as described above, the simple processing of providing an
opening in the side wall of the case can provide a piezoelectric buzzer which operates stably even
at low temperature while the case size is kept small.