JPH054391Y2 - - Google Patents

Description

[Detailed explanation of the invention] A. Purpose of the invention (industrial application field) This invention can be used, for example, to be incorporated into a telephone handset and to convert sound to electricity for sending or receiving calls. This invention can be used in piezoelectric electroacoustic conversion units.

(Prior Art) Telephones and other communication devices, transmitters used in measuring instruments, and units built into receivers are often used in noisy environments. It is made with low sensitivity to sounds with frequencies below 300Hz.

6-7 illustrate conventional units constructed to provide such characteristics.

That is, a thin plate-shaped piezoelectric element 1 with electrodes provided on both sides.
A metal circular diaphragm 2 with a diaphragm attached to the back surface is formed on the upper part of a circular frame 3 having a flat H-shaped longitudinal section in the diametrical direction (in this specification, the upper and lower portions refer to FIGS. 2 to 3 and 6). Place it on the stepped portion 3a, hold the diaphragm 2 at the closed upper end of the metal cylindrical casing 5 via the metal holding ring 4, stack the printed circuit board 6 under the frame 3, and caulk the lower end of the casing 5. It unites the whole immovably. A through hole 7 is formed in the center of the frame 3, and an acoustic resistance cloth 8 is formed to cover this hole.
Paste it on the frame. Sound grooves 9 are formed at several places on the outer surface and upper and lower surfaces of the frame 3, and a sound groove 10 that matches the sound grooves 9 is also formed on the upper surface of the restraining ring 4.
form. Several sound holes 11 are bored in the upper surface of the casing 5.

Inside the unit, there are a first chamber 12 sandwiched between the casing 5 and the diaphragm 2, a second chamber 13 sandwiched between the diaphragm 2 and the frame 3, and a third chamber 14 sandwiched between the frame and the printed circuit board 6. It is divided into.

When a sound wave arrives from above in FIG. 6, it enters the first chamber 12 through the sound hole 11 and causes the diaphragm 2 to vibrate. For this reason, the piezoelectric element 1 attached to the diaphragm
Since the voltage between the electrodes on both sides of the probe changes, it is possible to extract this voltage and obtain an electrical signal corresponding to the frequency and sound pressure of the sound wave. The above electric signal is transmitted by connecting the electrode on the bottom surface of the piezoelectric element 1 in FIG. By connecting to the terminal 6b of the printed circuit board 6 via the casing 5, it can be taken out between the terminals 6a and 6b. When the frame 3, restraining ring 4, etc. are insulators, signals can be taken out using conductive wires like the bottom electrodes.

A part of the sound waves entering the first chamber 12 enters the third chamber 14 from the sound groove 10 of the suppression ring through the sound groove 9 of the frame 3, and further passes through the resistance cloth 8 and the sound hole 7 to the second chamber. 13, which provides resistance to the vibration of the diaphragm 2. The number and size of sound grooves 9 and 10,
By adjusting the resistance cloth 8, etc., the sensitivity of the unit to sounds with frequencies below 300Hz is reduced.

In the case of a transmitter, by applying a signal voltage to the electrode of the piezoelectric element 1, the diaphragm 2 is vibrated,
It is possible to attenuate frequencies below Hz to produce sound.

(Problems to be solved by the invention) The conventional transmitting/receiving unit configured as described above uses a restraining ring 4 in which a sound groove 10 is formed.
Since the sound groove 10 is assembled while matching the sound groove 9 of the frame 3, manufacturing and assembling the restraining ring is troublesome, and the manufacturing efficiency of the unit as a whole is poor.

B. Structure of the invention (means for solving problems) This invention consists of a diaphragm 2 to which a thin plate-like piezoelectric element 1 is attached, which has a flat H-shaped longitudinal section and is covered with an acoustic resistance cloth 8. Place the frame 3 on the frame 3, which has the through hole 7 inside, overlap this and the printed circuit board 6, fit it into the cylindrical casing 5 which has the sound hole 11 at one closed end, and caulk the open end of the casing 5. In a piezoelectric electroacoustic transducer unit in which a diaphragm 2, a frame 3, and a printed circuit board 6 are combined, a stepped portion 17 is formed on the outside of the frame 3, and the diaphragm 2 is mounted on a raised receiving portion 18 on the inside. A space 20 is formed between the step part 17, a plurality of sound grooves 9 are formed on the outer side of the frame 3 to allow the space 20 to communicate with the inside of the frame, and a cutout part 19 is formed on the edge of the diaphragm 2.
Attach the edge of the diaphragm 2 to the casing 5 at the receiving part 1 of the frame.
The above-mentioned problems are solved by obtaining a piezoelectric electroacoustic transducer unit formed by intermittent inner protrusions 16 pressed against the piezoelectric transducer 8.

(Function) The edge of the diaphragm 2 is cut out to form a gap between it and the casing 5, so this is connected to the sound groove 9.
When fitted to the casing 5 together with the frame 3 provided with a By caulking the lower part of the casing 5 while pressing it against the upper surface of the frame, the unit can be assembled by immovably connecting each part without using a restraining ring.
Therefore, there is no need to manufacture and use a restraining ring as in the past, and the unit can be manufactured efficiently.

(Example) Figures 1 to 5 show examples of the present invention, where Figure 1 is a plan view of the unit, Figure 2 is a sectional view taken along line A-A in Figure 1, and Figure 3 is a perspective view of the frame. FIG. 4 is a plan view showing the overlapping of the diaphragm and the frame, and FIG. 5 is a plan view showing another example of the diaphragm.

Portions equivalent to those of the conventional example described above are indicated by the same reference numerals, and will be described below without explanation.

On the closed upper surface of the aluminum cylindrical (not necessarily cylindrical) casing 5, inner surface protrusions 16 are provided intermittently on the outer peripheral edge of the casing 5, which are pushed downward and protrude toward the inner surface. Frame 3 is
It has a circular shape that fits into the casing 5, and as shown in FIG.
The raised upper surface of the inner part serves as a receiving part 18 that supports the diaphragm. Frame 3 has a step 1
Four sound grooves 9 are formed that communicate with the third chamber 14 of the frame through the upper surface, side portions, and lower part of the frame.

As shown in FIG. 4, the diaphragm 2 has notches 19 formed by cutting out straight lines at six points from the circular edge.
It has a hexagonal shape with a short arc at the top corner.
Since this notch is for forming a gap through which sound waves pass between the diaphragm and the casing, it may have a shape as shown in FIG. 5, for example.

When this diaphragm 2 is stacked on the frame 3, it becomes as shown in FIG. That is, some of the sound grooves 9 are formed by the notch 1.
A space 20 is formed between the end of the diaphragm 2 and the stepped portion 17, and a part of the sound groove is covered by the diaphragm 2 and is located below the diaphragm 2. .

In this state, the diaphragm 2 and the frame 3 are fitted into the casing 5, the printed circuit board 6 is stacked downward, and the lower end of the casing 5 is caulked, and each part is immovably connected to assemble the unit as shown in Fig. 2. be able to.

When a sound wave arrives from above in FIG. 2, it enters the first chamber 12 through the sound hole 11 and vibrates the diaphragm 2, allowing the piezoelectric element 1 to extract an electrical signal.

On the other hand, a part of the sound waves that entered the first chamber 12 pass between the inner surface protrusions 16 and exit to the inner peripheral part of the casing 5, and then pass between the notch 19 of the diaphragm and the casing and enter the space 20. enter. This sound wave further passes through the sound groove 9, the third chamber 14, the resistance cloth 8, and the through hole 7 to the second chamber 13.
and provides resistance to the movement of the diaphragm 2.

Although the above embodiments have been described with respect to a transmitter, the same applies to a receiver.

C. Effect of the invention The invention provides that the inner protrusion 1 is intermittently formed on the casing 5.
6 is formed to sandwich the diaphragm 2 between it and the receiving portion 18 of the frame, so the conventional restraining ring 4 is not necessary. Furthermore, since the notch 19 is formed on the edge of the diaphragm and the space 20 is formed below it, no matter how the positional relationship between the notch 19 and the sound groove 9 is, the first chamber is It communicates with the second chamber 13 through the notch 19, the space 20, the sound groove 9, etc., and therefore, when assembling the unit, there is no need to consider aligning the positions of the sound groove 9 and the notch 19. , the unit can be assembled efficiently.

[Brief explanation of the drawing]

1 to 5 show an embodiment of the present invention, FIG. 1 is a plan view of the unit, FIG. 2 is a sectional view taken along line A-A in FIG. 1, FIG. 3 is a perspective view of the frame, and FIG. 4 is a plan view of the unit. A plan view of the stacked frames and diaphragm, Fig. 5 is a plan view showing another example of the diaphragm, and Fig. 6 is a plan view of the second example of the conventional unit.
FIG. 7 is a sectional view similar to the one shown in the figure, and a plan view of the frame thereof. DESCRIPTION OF SYMBOLS 1... Piezoelectric element, 2... Vibration plate, 3... Frame, 3a... Step part, 4... Holding ring, 5... Casing, 6... Printed circuit board, 6a, 6b...
Terminal, 7... Through hole, 8... Acoustic resistance cloth, 9, 10
... Sound groove, 11 ... Sound hole, 12 ... First chamber, 13
...Second chamber, 14...Third chamber, 15...Conductor, 1
6... Inner surface protrusion, 17... Step part, 18... Receiving part,
19...notch, 20...space.

Claims (1)

[Scope of utility model registration request] A diaphragm 2 to which a thin plate-shaped piezoelectric element 1 is attached is placed on a frame 3 having a flat H-shaped vertical cross section and a through hole 7 covered with an acoustic resistance cloth 8, and a printed circuit board 6 piezoelectric electroacoustic transducer in which the diaphragm 2, frame 3, and printed circuit board 6 are combined by stacking them and fitting them into a cylindrical casing 5 having a sound hole 11 at one closed end, and caulking the open end of the casing 5. In the unit, a step 17 is formed on the outside of the frame 3, and a space 20 is formed between the step 17 and the diaphragm 2 placed on the raised inner receiving portion 18, and the space 20 is formed inside the frame. A plurality of sound grooves 9 are formed on the outer side of the frame 3, and a notch 19 is formed on the edge of the diaphragm 2.
A piezoelectric electroacoustic transducer unit is formed by intermittent inner protrusions 16 that press the edge of the diaphragm 2 against the receiving part 18 of the frame.