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BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a structural example of an electromagnetic
buzzer of a watch alarm. FIG. 2 shows an example of a drive circuit of an electromagnetic buzzer.
FIG. 3 shows an example of the shape of a conventional electromagnetic type buzzer diaphragm,
and FIG. 4 is a diagram showing its vibration mode. FIG. 5 is an example of the shape of a
diaphragm for an electromagnetic buzzer according to the present invention, and FIG. 6 is a view
showing its vibration mode. The numbers in the figure are 1 ... core, 2 ... coil, 3 ... durable magnet,
4 ... diaphragm, 5 ... buzzer coil, 6 ... transistor.
DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the mobile shape
VC of an electrode type buzzer for a 111i 1 watch. The purpose of the present invention is to
miniaturize a buzzer of an alarm watch, to generate a buzzer with high conversion efficiency, and
to provide a buzzer with good frequency characteristics. Fig. 1 shows an example of the
electromagnetic type 1-w r / □ C θ <(The structure of the magnetic used for the alarm of the
wristwatch, and the magnetic core 1 made of magnetic material, the coil 2 for driving the city
magnet, the city magnet It consists of a durable magnet 5 for making it polar and an imaging
plate 4 made of a magnetic material or the like. In addition, for the vibration @ &, a gold region of
paper, plastic, nonmagnetic material, a metal member of magnetic material, etc. can be applied,
and usually a weight made of a magnetic material for causing magnetic excitation to the
vibration plate. Attach 5 As for the drive of the buzzer, it is most effective to take a direct current
pulse IJI that applies a pulse voltage to the input on the base side with the coil 6 of the magnet as
the @ -contact load of the transistor 7 shown in FIG. It is simple. FIG. 5 is a drawing of a
conventional imaging plate, which is an example of a circular imaging plate in which a piece 5 of
a-type material is attached to a diaphragm 4 made of paper, plastic and metal. . The swing is
normally fixed to a buzzer case as shown in FIG. 1 and is adhesively fixed to the case from the
viewpoint of requiring waterproofness, particularly when used for a watch. Therefore, when
driving the buzzer, it is possible to consider shooting (& working mode, model 2-Z of FIG. 1 IC).
The feature of this model is that deformation of the diaphragm is hardly observed around the
fixed end of the diaphragm and the weight of the magnetic material which can be regarded as a
rigid body. That is, in such a diaphragm, the amplitude of the central portion of the diaphragm
and the area of the diaphragm effective for vibration can not but be reduced as expected from
the actual shape and size. Therefore, the volume of the buzzer depends on the amplitude of the
diaphragm. In addition, the characteristic imaging frequency ω is given by the following
equation for this circular irradiance provisional. ,-People, m]--a "5 ((1-σ3) symbol a is radius of
diaphragm, h is thickness of rod of diaphragm, E is Young's modulus, ρ is density, σ is Poisson's
ratio , And αm is a proportional constant. The equation (1) shows that when the electromagnetic
buzzer is miniaturized for use in a watch, the radius of the diaphragm must of course be reduced,
so the smaller the buzzer is, the (2) vibration of the diaphragm The number must be high.
However, from an ergonomic point of view, it is needless to say that an alarm that gives the
human ear a good sound in the human ear is, of course, practical, so this natural frequency is
reduced by 2 to 4 KHz and the resonance point is It is desirable to drive the buzzer.
By the way, diameter 8 sm, thick 27100 wm 円 形 circular S! Although a buzzer having a
resonance point at around 4 KHz is realized, the design is almost close to the limit and there are
many difficult points. From this point of view, it is an object of the present invention to realize a
smaller watch buzzer, which has a sufficient sound volume and a satisfactory frequency
characteristic. @ 5 is an example of a circular moving plate based on the present invention, and it
is possible to insert one fold of S-shaped or U-shaped cross section around the fixed end of the
diaphragm according to the shape of the fixed rod It is. In the am board of this う structure, the
folds of the moving plate play a springing role, and the mode of the driving changes from that of
a simple circular moving plate. FIG. 6 shows the vibration mode of the circular imaging plate
based on the present invention, and it can be readily understood that the piston movement of the
simple circular 4-diaphragm machining diaphragm of FIG. . That is, it can be seen that the weight
attached to the center acts as a rigid plate and the peripheral plate of the peripheral plate works
effectively as a rigid plate) 11 so that it moves up and down. As shown in FIG. 5, a circular
diaphragm having the same dimensions as the circular diaphragm ↓ has a larger effective area
for photographing movement, and can have a wider eyelid width for photographing movement.
In other words, even if the radius a is the same as that of the circular circular diaphragm, the
actual effect is expected to be that the radius a is plus α. If calculation is made, the effect of the
temporary 1 + s diameter wire receiver is 1 to 2 KT (Z increase at the movement of the resonance
point, so this effect is effective in miniaturizing the buzzer to 1%. In addition, since the central
portion of the photographing plate approaches single piston movement, the wave number
characteristics with respect to the drive system are good, and the volume also increases. From
this point of view, it is thought that, if the idea of the present invention is further advanced,
incorporating a fold around the magnetic material will be effective for the same reason. As
described above, the present invention is effective for further downsizing of the buzzer of the
alarm watch 5-, generation of the buzzer sound with high efficiency of one sound acoustic
conversion, and improvement of the frequency characteristic.