JPS58143392A - Piezo-electric vibration type alam - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a drive circuit, and relates to one used, for example, in an automobile horn or an alarm horn for general equipment.

Alarm alarms using piezoelectric vibrators have conventionally emitted only a small sound pressure, and it has been extremely difficult to make them emit a large sound pressure like an automobile alarm.

The present invention reduces the sound pressure of a horn using a piezoelectric vibrator (2) The purpose is to obtain a structure that can be improved.

For this purpose, the present invention provides a structure in which a supporting member is brought into contact with a node of vibration in the second resonance state of the piezoelectric vibrator, and the piezoelectric vibrator is attached to the horn main body via the supporting member. A barrier member having an outer diameter substantially equal to the diameter of an inner vibrating section that is a portion of the piezoelectric vibrator located inside the node and facing the inner vibrating section is attached to the horn main body, and the piezoelectric vibrator The sound waves generated from the outer vibrating part, which is a part of the piezoelectric vibrator, located on the outer circumferential side of the node part are radiated from the slit or small hole of the horn main body.

First, the inventor learned that the vibration mode of a piezoelectric vibrator vibrates in a very uniform and beautiful waveform compared to the diaphragm of a conventional electromagnetic vibration type pawn. In other words, when the piezoelectric vibrator is vibrated, as shown in Fig.
A vibration node 3Y is formed inside the first layer, and three waves 3a are formed.
, 3b, 3b are formed neatly. and,
We focused on the fact that the phases of the wave 3b outside the node 3Y and the wave 3a inside the node 3Y are opposite to each other. And piezoelectric vibration (
3) I surmised that the reason why the sound pressure does not decrease -L when using a movable element is that the sound waves that are 180' out of phase with each other cancel out each other's sound waves. be. When we conducted an experiment based on this assumption, we found that the node 3Y
It has been found that the sound waves emitted from the outer side 3b of the node 3Y are more powerful than the sound waves emitted from the inner side 3a. In order to prevent the sound waves generated by the vibration of the inner side 3a of the joint 3Y from interfering with the sound waves generated by the outer side 3b, a barrier member was installed facing the inner side 3a of the joint 3Y. However, Example 3 will be described below, in which a clear increase in the sound pressure generated from the entire horn was confirmed.

FIG. 4 is a front view showing the first embodiment of the horn according to the present invention, and FIG. 5 is a sectional view taken along line A-A.

Reference numeral 1 denotes a case molded from synthetic resin, and has a ring-shaped protrusion 1a. The tip of the protrusion 1a has a recess with a semicircular cross section, and an O-ring 2 made of rubber with low hardness is inserted into this recess.

5 is also a case made of synthetic resin, and has a cross section with the same dimensions as 1 (4) and a semicircular depression. Place an O-ring 4 similar to 2 in this recess, place a first piezoelectric vibrator 3 between these two O-rings 2 and 4, and place the first piezoelectric vibrator 3 with its center aligned with the center of the O-rings 2 and 4. It's stuck in there. Further, the outer circumferential portion 5a that forms the boundary between the cases 1 and 5 is fixed, for example, by adhesive. The center diameter l between the O-rings 2 and 4 corresponds to the vibration mode during the second resonance of the first piezoelectric vibrator 3 (Fig. 8).
It is matched with the inner node of .

Note that piezoelectric vibrators with a large difference in diameter between the pressure element and the diaphragm, such as those used in this type of alarm, exhibit a secondary resonance state as shown in Figure 1 when the sound pressure is high. It is known to collapse.

The case 5 has a shallow cylindrical recess on the surface opposite to the surface on which the O-ring is set, and a piezoelectric speaker serving as a second piezoelectric vibrator consisting of a sounding body with a relatively flat frequency characteristic is installed in this portion. Store 6.

By adhering or fitting the cover 7 to the case 5, the piezoelectric speaker 6 is held between the cover 7 and the case 5. In this case, the first piezoelectric vibrator (5) 3 and the piezoelectric speaker 6 are arranged coaxially, and the first piezoelectric vibrator (5) 3 and the piezoelectric speaker 6 are arranged coaxially.
The front side of the center part of the piezoelectric vibrator 3 will be covered with a disc-shaped piezoelectric speaker 6, and as shown in Fig. are shifted by 180° (that is, are displaced in the opposite direction), and during the second resonance in Figure 1, the sound pressure due to the vibration of the outer part 3b of the node is higher than that of the inner part 3a of the node. Since the sound pressure is larger than the sound pressure caused by the vibration of If the central part of the element 3 is removed with a structure in which the piezoelectric speaker 6 covers it, the sound pressure efficiency can be increased.

A slit 1b is provided on the side surface of the case 1. The slit 1b allows the sound emitted by the first piezoelectric vibrator 3' to be
This is a sound emitting hole that allows sound reflected on a surface parallel to the piezoelectric vibrator 3 of the case 1 to escape from the inside of the case 1. Note that the sound to the front is radiated through the slit 5b of the case 5.

(6) The case 1 also has a circuit housing IC. This storage section has two grooves IC1゜1c2 facing each other at the top and bottom.
A circuit board 8 for driving the first piezoelectric vibrator 3 and the piezoelectric speaker 6 is inserted and housed in the lower groove 1c2. upper groove 1
Step-up transformers 9 and 10 for sound pressure amplification are inserted and housed in cl.

Numeral 11 is a spacer for magnetic shielding that prevents the cores between the transformers 9 and 10 from coming into contact with each other and causing magnetic flux interference, and is made of resin or brass.

Next, 12 disc-shaped covers are fixed to the case 1 by attaching and fitting them, and the circuit board 8 and step-up transformers 9 and 10 are fixed.
Fix it to case 1.

The circuit board 8 and the electrode 3e of the first piezoelectric vibrator 3 and the circuit board 8 and the electrode 6e of the piezoelectric speaker 6 are connected by thin flexible wires.

13 is a rubber bush for sealing between the wires 14 and 15 and the case 1. Wires 14,15 are for power supply and are connected to the two-J connector 16. 1d (J vehicle mounting stay.

As described above, in the above embodiment, the disc-shaped piezoelectric vibrator (7) is supported at the vibration node 3Y of the piezoelectric vibrator 3 in the device that vibrates the movable element 3 and generates an alarm sound. Place the piezoelectric vibrator 3 onto the horn main body 1, 5 via the supporting member 2.4 by bringing the O-rings 2, 4 into contact with each other.
A second piezoelectric vibrator serving as a barrier member facing the inner vibrating portion 3a and having an outer diameter approximately equal to the diameter l of the inner vibrating portion 3a that is a portion of the piezoelectric vibrator 3 located inside the node portion 3Y. 6 is attached to the horn main bodies 1 and 5, and the sound waves generated from the outer vibrating part 3b, which is a part of the piezoelectric vibrator 3 located on the outer peripheral side of the node 3Y of the piezoelectric vibrator 3, are used as the alarm sound. 1.5 slits (small holes are fine) 5b of the vessel body,
1b emits radiation and u.

Further, the barrier member is the piezoelectric vibrator, that is, the first piezoelectric vibrator 3.
It consists of a second flat piezoelectric vibrator 6 which is provided separately and has a smaller diameter than the piezoelectric vibrator 3, and the second piezoelectric vibrator 6 is, for example, a piezoelectric speaker having a flat wave number characteristic. The first piezoelectric vibrator 3 is arranged substantially parallel to and substantially concentric with the first piezoelectric vibrator 3, and has a fundamental frequency lower than that of the first piezoelectric vibrator 3. (8) A voltage is applied to cause vibration.

Next, an electric circuit for driving the vibrators 3 and 6 will be explained.

FIG. 4 shows the elements mounted on the circuit board, step-up transformer 9.10, and step-up transformer 9.10. This is a drive circuit composed of a second piezoelectric vibrator 3.6.

To briefly explain the operating principle, 17 and 18 are Darlington-connected transistors, which self-oscillate by inputting the feedback signal of the first piezoelectric vibrator 3, which has three terminals, to the base of the transistor 18 via the resistor 19. . 9 is a boost lance, the number of turns on the primary side: the number of turns on the secondary side is 1
: 5 to 7 and the number of turns on the secondary side is larger than the primary side Ladder 2
A higher voltage is generated on the secondary side than on the primary side. When the emitter-minus voltage of the transistor 17 is applied to the primary side of the transformer 9 via the transistor protection diode 20, a boosted voltage is generated on the secondary side. Then, by applying this voltage to the first piezoelectric vibrator 3, the sound pressure of this piezoelectric vibrator is amplified. 21 is a resistor (9) for starting oscillation. Note that the self-excited oscillation circuit described above is itself known.

Next, the negative side of the diode 20 is connected to the 1 transistor 2
It is connected to the base of 2 through a resistor. The collector of the transistor 22 is connected to the positive terminal of the on-vehicle power supply via the resistor 24, and a waveform close to a rectangular wave with the negative component of the self-oscillation waveform removed is generated between the collector and negative terminal of the transistor 22. 25 is a counter IC forming a frequency dividing circuit for dividing the automatic oscillation frequency, and uses a C-MOS IC. A self-excited oscillation frequency signal is input to the clock input of the counter 25, and a divided frequency signal appears at its output OUT side, and this signal is input to the base of the transistor 26 via the resistor 27.

The collector of the 1 transistor 26 is connected to the plus side of the power supply via the primary coil of the step-up transformer 10 similar to that described above. When the transistor 26 is turned on and off at a frequency obtained by dividing the self-oscillation, a voltage waveform of the frequency divided by (10), which is boosted, appears on the secondary side of the step-up transformer 10.
The signal is applied to a second piezoelectric vibrator (piezoelectric speaker) 6 having a Furano frequency characteristic and connected to a secondary coil of the same.

The voltage applied to the piezoelectric vibrator 6 is a rectangular wave passed through a transformer, and contains various frequency components with the divided frequency as the fundamental frequency, resulting in a thick tone. Therefore, by mixing the pure tone of a single frequency emitted by the first piezoelectric vibrator 3 with the sound of the second piezoelectric vibrator 6 including the frequency-divided frequency component, the timbre becomes softer by δ1.

A diode 28 protects the element and the IC when the terminal polarities are reversely connected.

It is preferable that the first piezoelectric vibrator 3 that automatically oscillates has a frequency characteristic with a large Q value during resonance as shown in FIG. 5 in order to suppress the sound pressure. Further, in order to soften the tone, it is preferable to use the second piezoelectric vibrator 6 as shown in FIG. 3, which has a flat frequency characteristic that produces a tone even at low frequencies.

Also, as shown by the broken line, a transistor 27a and a resistor 27b are added to feed back the frequency-divided signal (when modulated,
You can get different tones.

The above circuit (J) oscillates the separately excited second piezoelectric vibrator with a low frequency component by dividing the self-excited oscillation signal, so there is no need for a dedicated drive circuit for the second piezoelectric vibrator. , the circuit can be simplified and a device that emits an alarm with a good tone can be obtained.

Next, FIG. 7 is a front view showing a second embodiment of the present invention alarm, and FIG. 8 is a sectional view taken along line BB. In this example,
Two piezoelectric vibrators are arranged in a plane. The numbered portions in FIGS. 7 and 8 correspond to the numbered portions in FIG. 5. The barrier member in this second embodiment is provided with no slits or small holes, or has fewer slits or small holes than the number of slits or small holes facing the outer vibrating portion through which the sound waves generated from the outer vibrating portion pass. It consists of a front wall portion 5z of the horn main body provided with a slit or small hole.

As described above, in the present invention, since the inner vibrating part and the first side vibrating part, which generate sound waves with different phases from each other, cancel each other's sound waves so that they do not cancel each other out, it is possible to This has the effect of producing an alarm that generates a large sound pressure.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram for explaining the vibration mode of the piezoelectric vibrator used in the present invention, FIG. 2 is a front view of a horn according to the first embodiment of the present invention, and FIG. The illustrated A-A sectional view, FIG. 4 is an electric circuit diagram adopted in the first embodiment, and FIGS. 5 and 6 are sound pressure versus frequency characteristics diagrams of the piezoelectric vibrator used in the first embodiment. , FIG. 7 and FIG. 8 are a front view and a sectional view taken along the line B-B of a second embodiment of the present invention. 3...First piezoelectric vibrator, 3Y...Node, 2, 4...
・For example, an O-ring that serves as a support member, 1.5... the horn main body, 3a... the inner vibrating part, 6 or 5z... the second piezoelectric vibrator 6 that serves as a barrier member, and the horn main body. Front wall part 5
z, 3b...Outer vibration part, 1b, 5b...Slit or small hole. (13) 1st Kyōichi

Claims (3)

[Claims] (1) In a device that generates an alarm sound by vibrating a disk-shaped piezoelectric vibrator, a supporting member is brought into contact with and tightened at the node of vibration of the piezoelectric vibrator in the secondary resonance state, and The piezoelectric vibrator is attached to the horn main body via a support member, and the inner vibrating portion has an outer diameter approximately equal to the diameter of the inner vibrating portion that is a portion of the piezoelectric vibrator located inside the node. A facing barrier member is attached to the horn main body, and the sound waves generated from the outer vibrating part, which is a part of the piezoelectric vibrator, located on the outer circumferential side of the node of the piezoelectric vibrator are transmitted through the slit of the horn main body. Or a piezoelectric vibrating alarm characterized by emitting radiation from a small hole. (2) The barrier member has no slits or small holes, or has fewer slits or small holes than the slits or small holes facing the outer vibrating part through which the sound waves generated from the outer vibrating part pass. The piezoelectric vibrating horn according to claim 1, characterized in that: (1) consists of a front wall portion of the horn main body provided therein. (3): The barrier member is composed of a second flat piezoelectric vibrator provided separately from the piezoelectric vibrator, that is, the first piezoelectric vibrator, and has a smaller diameter than the piezoelectric vibrator, and the second piezoelectric vibrator The piezoelectric vibrator according to claim 1, wherein the element is arranged substantially parallel and substantially concentrically with the first piezoelectric vibrator and vibrates in a frequency range lower than that of the first piezoelectric vibrator. Type V combined volume.