JP4029213B2 - Method for manufacturing piezoelectric sound producing component - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a piezoelectric sound producing part such as a piezoelectric buzzer or a piezoelectric sounder.
[0002]
[Prior art]
[Patent Document 1]
JP, 7-274299, A Conventionally, in electronic equipment, household appliances, cellular phones, etc., piezoelectric sounding parts have been widely used as piezoelectric sounders or piezoelectric buzzers that generate alarm sounds and operation sounds. The piezoelectric sound producing component is, as in Patent Document 1, housed in a casing, and bonded and fixed by applying a silicone adhesive and curing the periphery of the diaphragm and the inner wall of the casing. There are many. Examples of the vibration plate include a unimorph type vibration plate in which a piezoelectric plate is attached to one side of a metal plate, and a bimorph type vibration plate in which a plurality of piezoelectric ceramic layers are stacked.
[0003]
FIG. 1 shows an example of a piezoelectric sound producing component, where 1 is a housing, 2 is a diaphragm, and 3 is a terminal. The peripheral edge of the diaphragm 2 is supported on the support 1 a of the housing 1 and fixed by the silicone adhesive 4.
[0004]
FIG. 2 shows a general manufacturing process of the piezoelectric sound producing component as described above. That is, the diaphragm 2 is accommodated in the housing 1 (step S1), the terminals 3 are assembled (step S2), and then the silicone adhesive 4 is applied (step S3). Next, the silicone adhesive 4 is cured by a curing device such as an oven (step S4). Thereafter, a predetermined frequency signal is applied to the diaphragm 2 to generate a ringing sound and perform sound pressure selection (step S5).
[0005]
[Problems to be solved by the invention]
However, since the curing process takes a much longer time (for example, 60 minutes) than the other processes, only the curing process is a batch process, making it difficult to make automatic equipment lines. As a result, there was a problem that the production line was divided in the curing process, and an auxiliary work by the operator was required.
[0006]
In addition, sound pressure measurement of a sound generating component that generates a ringing sound at a single frequency, such as a piezoelectric buzzer or a piezoelectric sounder, is performed in a room called an anechoic room where no sound is reflected. However, the anechoic chamber is one large room, and it is impossible to incorporate this into an electronic component manufacturing facility. For this reason, it is necessary to separately provide equipment for carrying out the process from housing of the diaphragm to application of the adhesive and equipment for measuring the sound pressure, resulting in a disadvantage that the equipment cost increases.
[0007]
SUMMARY OF THE INVENTION An object of the present invention is to provide a method for manufacturing a piezoelectric sounding part that can automate a manufacturing line and eliminate an auxiliary operation by an operator during the process.
Another object of the present invention is to provide a method for manufacturing a piezoelectric sounding part capable of providing, in one manufacturing facility, equipment for carrying out from storage of a diaphragm to application of an adhesive and equipment for measuring sound pressure. It is in.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the invention according to claim 1 is characterized in that a piezoelectric diaphragm is housed in a housing, and non-flowable silicone is provided between the periphery of the piezoelectric diaphragm and the inner peripheral portion of the housing. In a method for manufacturing a piezoelectric sound producing part in which an adhesive is applied and cured, a predetermined frequency signal is applied to the piezoelectric diaphragm before and after the silicone adhesive is cured for some sample products. This process consists of a pre-process for measuring pressure and obtaining a correlation between sound pressure values, and a main process to be performed on an actual product. The main process is performed on the piezoelectric diaphragm before the silicone adhesive is cured. the sound pressure measured by the frequency signal application, a first step of selecting the quality of the correlation, after the selecting step, the second curing the silicone adhesive for non-defective discriminated product piezoelectric having between steps, the To provide a method of manufacturing a sound parts.
[0009]
In the present invention, by setting the time-consuming curing step as the final step, the previous steps (housing of diaphragm, application of silicone adhesive, sound pressure selection, etc.) can be made into a continuous line, and the equipment cost is reduced. In addition to cost reduction, it is possible to eliminate auxiliary work by the operator during the process.
In addition, since the curing process is performed after the sound pressure selection process, it is only necessary to perform the curing process for products determined to be non-defective by the sound pressure selection, and the curing process can be performed efficiently. That is, since the curing process can be omitted for a product determined to be defective, waste can be eliminated.
The silicone adhesive used in the present invention must be non-flowable. When a fluid silicone adhesive is used, when the piezoelectric diaphragm is driven for sound pressure measurement / selection, the silicone adhesive will flow and the diaphragm will move or the sound pressure will become unstable. This is because the problem of
As a method for curing the silicone adhesive, known methods such as moisture absorption curing and heat curing can be used.
[0010]
As in claim 2, it is preferable to use a silicone adhesive having a viscosity before curing of 500 Pa · s or more.
If a silicone adhesive with a viscosity before curing of 500 Pa · s or less is used, the silicone adhesive has fluidity, so if you try to sort the sound pressure before curing, the original sound pressure may not be obtained or the adhesive Will flow.
By using a silicone adhesive having a viscosity of 500 Pa · s or higher before curing, the adhesive does not flow during sound pressure selection, and the original sound pressure can be obtained.
[0011]
In the present invention, the sound pressure before and after curing of the silicone adhesive is measured, and the manufacturing method of the present invention is applied to a piezoelectric sound producing component having a correlation between the sound pressure values .
Some piezoelectric sound producing parts have no correlation between the sound pressure values before and after curing of the silicone adhesive. When the present invention is applied to such a piezoelectric sound generating component, even if it is determined to be a good product before curing, the sound pressure characteristics after curing may be defective, and the reliability of sound pressure selection before curing is reduced. To do.
Therefore, before carrying out the present invention, the sound pressure before and after curing of the silicone adhesive is measured as a pre-process, and the presence / absence of correlation between the sound pressure values is determined and correlated (for example, before and after curing). By implementing the present invention only for the piezoelectric sound producing parts (the sound pressure of which is substantially proportional), it is possible to ensure the reliability of the sound pressure selection before curing.
[0012]
As in claim 3 , the step of applying a predetermined frequency signal to the piezoelectric diaphragm and measuring the sound pressure is performed by a simple sound pressure measuring device having a correlation with the sound pressure characteristics of the piezoelectric sound producing component in the anechoic chamber. It is better to measure.
If the sound pressure is measured using a simple sound pressure measuring device that has a high correlation with the measurement in the anechoic chamber, the equipment size can be reduced, and the equipment from the storage of the diaphragm to the application of the adhesive can be reduced. The facility for measuring the sound pressure can be provided in one manufacturing facility, and the manufacturing facility can be made continuous, and at the same time the measurement time can be shortened, so that the manufacturing efficiency can be improved.
As a simple sound pressure measuring device, for example, a sound pressure measuring device (Japanese Patent Application No. 2002-112987) previously proposed by the applicant of the present application may be used. This device attaches one end of an adapter having a directivity of measurement sound to the sound pressure measurement artificial ear with a built-in microphone, and an air chamber having a resonance frequency larger than the measurement frequency of the piezoelectric sound producing part inside, The ringing sound is measured with an artificial ear through the adapter by ringing the piezoelectric sounding part while pressing the piezoelectric sounding part against the seating surface of the other end of the adapter communicating with the air chamber. In addition, a piezoelectric sounding part is housed in a small soundproof box that does not reverberate, and the sound pressure characteristics when it is sounded are correlated with the sound pressure characteristics of the sounding sound of the piezoelectric sounding part in an anechoic chamber. You may use the apparatus which has.
Both devices are small and can be incorporated into a production line.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 3 shows a manufacturing process of the piezoelectric sound producing component according to the present invention.
The piezoelectric sound producing component used here is the same as that shown in FIG.
(A) of FIG. 3 is a pre-process, and for a plurality of piezoelectric sound producing parts as sample products, the sound pressure before and after curing of the silicone adhesive is measured, and the correlation between the sound pressure values is examined.
That is, the diaphragm 2 is accommodated in the housing 1 (step S1), the terminals 3 are assembled (step S2), and then the silicone adhesive 4 is applied (step S3). The coating operation can be automatically performed using a coating apparatus such as a dispenser. As the silicone adhesive 4, one having a viscosity before curing of 500 Pa · s or more, that is, a non-flowable one is used. And before the silicone adhesive 4 hardens | cures, an alternating current signal is applied to the diaphragm 2, and the sound pressure-frequency characteristic is measured (step S4). When the diaphragm 2 is vibrated, the silicone adhesive 4 is non-flowable, so there is no problem that the diaphragm 2 is displaced or the silicone adhesive 4 flows from the application position to the outside. Next, the silicone adhesive 4 is cured by a curing device such as an oven (step S5), an AC signal is again applied to the cured diaphragm 2, and its sound pressure-frequency characteristics are measured (step S6). The cross correlation between before and after curing is examined from the sound pressure-frequency characteristics measured as described above (step S7).
[0014]
FIG. 4 is an example of a sound pressure-frequency characteristic diagram before and after curing of the silicone adhesive. Here, an example of a piezoelectric sounder that requires a predetermined sound pressure at 4 kHz is shown.
FIG. 4 shows an example of a piezoelectric sound producing part having a correlation before and after curing. Before curing, a sound pressure peak occurs near a frequency of 3.3 kHz as shown by a broken line. The peak of is shifted to the high frequency side by approximately 0.2 kHz. The sound pressure difference at 4.0 kHz before and after curing is about 4 dB.
[0015]
FIG. 5A shows the measurement results of the sound pressure values before and after curing at a predetermined frequency in a plurality of examples in which the sound pressure values are correlated.
As is clear from FIG. 5 (a), in the piezoelectric sound producing component having a correlation, the sound pressure value before curing and the sound pressure value after curing are approximately proportional to each other. In this example, the correlation coefficient is It was 0.9 or more.
FIG. 5B is an example in which there is no correlation between before and after curing, and in the case of a piezoelectric sounding component that cannot be correlated in this way, even if the sound pressure before curing is measured, Sound pressure cannot be inferred.
[0016]
The step shown in FIG. 3B is performed on the piezoelectric sound producing component having the above correlation.
That is, the diaphragm 2 is accommodated in the housing 1 (step S1), the terminals 3 are assembled (step S2), and then the silicone adhesive 4 is applied (step S3). The casing 1, the diaphragm 2, the terminals 3, and the silicone adhesive 4 used here are the same as the sample products used in the previous step. A predetermined frequency signal is applied to the diaphragm 2 before the silicone adhesive 4 is cured, and a sound is generated to perform sound pressure selection (step S8). The above steps S1 to S3 and S8 can be implemented as a continuous line with one piece of equipment. By sound pressure selection in step S8, selection is made into non-defective products and defective products.
Next, only good products are carried to a curing device such as an oven to cure the silicone adhesive 4 (step S5). Since this curing process takes a long time of about 60 minutes, it is carried out by batch processing.
Since it has been known in advance that the piezoelectric sound generating part having the silicone adhesive 4 cured as described above has a correlation between the sound pressure before and after the curing in the previous process, the sound pressure selection is performed again. It has a sound pressure characteristic as a non-defective product.
[0017]
Sound pressure measurement of sounding parts that generate ringing sound at a single frequency, such as a piezoelectric buzzer or a piezoelectric sounder, is performed in a room called an anechoic room where no sound is reflected, but the equipment size is large. In addition, measurement time is required, and it is difficult to implement with one facility together with other processes such as vibration plate assembly, terminal assembly, and adhesive application. The applicant of the present application has developed a simple sound pressure measurement device that is small and highly correlated with measurement in an anechoic chamber (Japanese Patent Application No. 2002-112987).
[0018]
FIG. 6 shows an example of such a simple sound pressure measuring device.
Reference numeral 10 is a known artificial ear for measuring sound pressure. The artificial ear 10 includes a microphone 11, and a cylindrical earpiece mounting portion 12 projects from one end of the artificial ear 10. The receiving part of the microphone 11 faces the inside of the earpiece mounting part 12.
One end opening portion 27 of the adapter 20 is fitted to the earpiece mounting portion 12 and is appropriately fixed with a screw or the like. The adapter 20 is formed in a cylindrical shape with a metal material such as a copper alloy, and a seating surface 21 for pressing the piezoelectric sounder S is formed on the other end of the adapter 20. A communication hole 23 is formed at the center of the seating surface 21. An air chamber 24 communicating with the communication hole 23 is formed inside the adapter 20, and an opening hole 25 opened to the outside is formed on the side wall of the air chamber 24. The opening hole 25 of this embodiment is formed in a long hole shape in the axial direction, and a total of 12 opening holes are provided. The dimension of the air chamber 24 is set such that its axial length L is larger than the diameter d. Desirably, 2d ≧ L> d. The reason is that, assuming that the sounding sound of the piezoelectric sounder S is radiated at a radiation angle of about 90 °, the reflected wave reflected by the inner wall of the air chamber 24 is prevented from being directly received by the microphone 11 and directivity is improved. Is to increase
[0019]
FIG. 7 shows the sound pressure comparison data of the piezoelectric sounder S between the conventional measurement method A using an anechoic chamber and the measurement method B using the simple sound pressure measurement device.
In the conventional method A, a piezoelectric sounder S and a microphone are arranged in an anechoic chamber and the sound pressure thereof is measured. In the measuring method B, the sound pressure of the piezoelectric sounder S is measured using the sound pressure measuring device shown in FIG. It is measured. In A, the sounder S and the microphone were measured 10 cm apart, and in B, the sounder S and the microphone were measured 5 cm apart. As is apparent from FIG. 7, the sound pressure is increased by about 10 dB in the measurement method B compared to the conventional method A, but the correlation coefficient between both is 0.95 or more at 1 to 5 kHz including the resonance frequency 4 kHz of the sounder S. Yes, the measurement level by the measurement method B is equivalent to the reference level A. Therefore, it was confirmed that even if the adapter 20 was used, there was no great difference in measurement accuracy with the method using the anechoic chamber.
If the sound pressure is measured using such a simple sound pressure measuring device, the equipment size can be reduced and the measurement time can be shortened. can do.
[0020]
The present invention is not limited to the embodiment described above, and can be modified without departing from the spirit of the present invention.
For example, although the frequency of sound pressure measurement before and after curing of the silicone adhesive is made constant, the sound pressure measurement frequency before and after curing may be made different in anticipation of the shift amount.
In the above-described embodiment, an example in which the terminal is assembled after the silicone adhesive is applied has been described. However, instead of the terminal, a lead wire connected to the diaphragm in advance by soldering or the like may be used. In this case, when the diaphragm is housed in the housing, the lead wire is also incorporated into the housing.
Further, a simple sound pressure measuring device is not limited to the one shown in FIG. 6 and can be incorporated in one production line and has a correlation with the sound pressure characteristics of piezoelectric sound producing parts in an anechoic chamber. Can be used.
[0021]
【The invention's effect】
As is apparent from the above description, according to the invention described in claim 1, since the sound pressure selection is performed before the silicone adhesive is cured, the time-consuming process for curing the silicone adhesive is selected. Can be implemented after. For this reason, diaphragm storage, terminal assembly, silicone adhesive application, sound pressure selection, etc. can be made into a continuous line, reducing equipment costs and eliminating operator assistance during the process. be able to.
In addition, since the curing process is performed after the sound pressure selection process, it is only necessary to perform the curing process for products determined to be non-defective by the sound pressure selection, and the curing process can be performed efficiently.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of an example of a general piezoelectric sound producing component.
FIG. 2 is a process diagram showing a conventional method of manufacturing a piezoelectric sound producing part.
FIG. 3 is a process diagram showing a method for manufacturing a piezoelectric sound producing component according to the present invention.
FIG. 4 is a sound pressure characteristic diagram showing a correlation between before and after curing of the silicone adhesive.
5A is a comparison diagram of sound pressure before and after curing when there is a correlation, and FIG. 5B is a comparison diagram of sound pressure before and after curing when there is no correlation.
FIG. 6 is a cross-sectional view of an example of a simple sound pressure measuring device.
FIG. 7 is a sound pressure comparison diagram of a piezoelectric sounder when an anechoic chamber is used and when a simple sound pressure measuring device is used.
[Explanation of symbols]
1 Housing 2 Piezoelectric diaphragm 3 Terminal 4 Silicone adhesive

Claims (3)

In a method for manufacturing a piezoelectric sound producing part, in which a piezoelectric diaphragm is housed inside a casing, and a non-flowable silicone adhesive is applied between the periphery of the piezoelectric diaphragm and the inner peripheral portion of the casing and cured. ,
For some sample products, before the silicone adhesive is cured and after it is cured, a predetermined frequency signal is applied to the piezoelectric diaphragm, the sound pressure is measured, and a correlation between the sound pressure values is obtained. ,
It consists of this process to be performed on the actual product,
The above process
A first step of applying a predetermined frequency signal to the piezoelectric diaphragm and measuring its sound pressure before the silicone adhesive is cured, and selecting pass / fail from the correlation ;
A second step of curing the silicone adhesive for a product determined to be non-defective after the selection step; The method for manufacturing a piezoelectric sound producing component according to claim 1, wherein the silicone adhesive has a viscosity before curing of 500 Pa · s or more. The step of applying a predetermined frequency signal to the piezoelectric diaphragm and measuring the sound pressure thereof is performed by a simple sound pressure measuring device having a correlation with the sound pressure characteristics of the piezoelectric sound producing component in the anechoic chamber. The method of manufacturing a piezoelectric sound producing component according to claim 1 or 2 .

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